Don Sheppard MD

• Associate Professor, Departments of Microbiology and immunology and Medicine, McGill University
• Program Director, McGill Royal College Training Program in Medical Microbiology and infectious Diseases, Montreal

https://rimuhc.ca/-/donald-sheppard-md

Cases of cholera are not commonly reported in the United States treatment zoster buy kaletra us, and most cases are considered imported cases treatment xanthelasma purchase kaletra 250 mg free shipping. Clinical Manifestations Cholera is an acute diarrheal disease spread mainly through contaminated water medications quiz order kaletra 250 mg. However treatment 247 purchase kaletra 250 mg fast delivery, improperly preserved and handled foods treatment quality assurance unit order 250mg kaletra with amex, including fish and seafood medicine kim leoni discount kaletra 250mg with amex, milk, ice cream, and unpreserved meat, have been responsible for outbreaks. The disease manifests in acute cases as a severe gastroenteritis accompanied by vomiting and followed by diarrhea. The stools produced by patients with cholera are described as rice water stools, and the number of stools, which are watery and contain numerous flecks of mucus, may be as many as 10 to 30 per day. If left untreated, cholera can result in a rapid fluid and electrolyte loss that leads to dehydration, hypovolemic shock, metabolic acidosis, and death in a matter of hours. The devastating clinical scenario is the result of a powerful enterotoxin known as cholera toxin, or choleragen. Once ingested, the bacteria colonize the small intestine, in which they multiply and produce choleragen. Once inside the cell, the active A1 subunit stimulates the production of adenylate cyclase through the inactivation of G protein. Treatment and management of cholera are best accomplished by the administration of copious amounts of intravenous or oral fluids to replace fluids lost from the severe diarrhea. The administration of antimicrobial agents such as doxycycline can shorten the duration of diarrhea and thereby reduce fluid loss; however, resistance to doxycycline has been reported. Therefore administration of additional antimicrobials such as azithromycin and ciprofloxacin may be necessary. Studies in Bangladesh, however, indicate a rapidly occurring reemergence of the classic biogroup. Numerous cases of Vibrio infections have been reported involving other serogroups, V. Vibrios can be differentiated from the similar genera Aeromonas and Plesiomonas (now classified in the family Enterobacteriaceae, see Chapter 19) by key biochemical and growth requirement characteristics, as shown in Table 20. Antigenic Structure Little is known about the antigenic structure of Vibrio except for V. Vibrio cholerae Epidemiology Vibrio cholerae O1 is the causative agent of cholera, also known as Asiatic cholera or epidemic cholera. Most epidemics occur in developing countries, in which it is endemic; in particular, cholera is prevalent in the Bengal region of India and Bangladesh. Because the G protein acts to return adenylate cyclase from its active to inactive form, the net effect is persistent activation of adenylate cyclase. In Sherris J, editor: Medical microbiology: an introduction to infectious diseases, ed 4, New York, 2004, McGraw-Hill, p. Other non-O1 serogroup strains have been implicated in a variety of extraintestinal infections, including cholecystitis, ear infections, cellulitis, and septicemia. The O139 strain contains the cholera toxin gene, ctx, and produces a disease that closely resembles cholera caused by V. Of interest is that some of these O139 strains share cross-reacting antigens with Aeromonas trota, a somewhat uncommon cause of diarrheal disease (discussed later). Vibrio parahaemolyticus Epidemiology Vibrio parahaemolyticus is the second most common Vibrio species implicated in gastroenteritis after V. In the United States however, it is the most frequently encountered species in clinical samples. This species was first recognized as a pathogen in Japan in 1950, when it was the cause of a large food poisoning outbreak; even today it is the primary cause of so-called summer diarrhea in Japan. Hence most cases of gastroenteritis can be traced to recent consumption of raw, improperly cooked, or recontaminated seafood, particularly oysters. Categorized by geographic regions, 543 isolates were reported in non-Gulf Coast states and 62 in Gulf Coast states. Patients have watery diarrhea, moderate cramps or vomiting, and little if any fever. Invariably the patient has a history of recent aquatic exposure or a water-associated traumatic injury to the infected site. However, there is a possible association between hemolysin production and virulence, known as the Kanagawa phenomenon. These strains are considered Kanagawa toxin-positive, whereas most environmental isolates are Kanagawa toxin-negative. There are exceptions to both these observations; however, and the exact role of this hemolysin in pathogenesis is still not understood. It is a common inhabitant of marine environments and is a strict halophile, requiring at least 1% NaCl; it is able to tolerate up to 10% NaCl. Almost all isolates originate from extraintestinal sources, such as eye and ear infections or wound and burn infections. The organism can be an occupational hazard for people in constant contact with seawater, such as fishermen or sailors. Laboratory Diagnosis Specimen Collection and Transport Vibrios are not fastidious, and only a few special collection and processing procedures are necessary to ensure the recovery of vibrios from clinical material. Whenever possible, body fluids, pus, or tissues should be submitted, but swabs are acceptable if they are transported in an appropriate holding medium, such as Cary-Blair, to prevent desiccation. Buffered glycerol saline is not recommended as a transport or holding medium because glycerol is toxic for vibrios. Strips of blotting paper soaked in liquid stool and placed in airtight plastic bags with a few drops of saline to maintain moisture are considered viable specimens for up to 5 weeks. Stool specimens should be collected as early as possible in the course of the illness and preferably before the administration of antimicrobial agents. It is therefore imperative to determine the oxidase activity of any suspicious Vibrio-like colony. There is great variation among different lots in Vibrio vulnificus Vibrio vulnificus can be found in marine environments on the Atlantic, Gulf, and Pacific coasts of North America. After cholera, the second most serious types of Vibrio-associated infections are those caused by V. The former is thought to occur through the gastrointestinal route after the consumption of shellfish, especially raw oysters. Patients with liver dysfunction and syndromes that result in increased serum levels of iron. Such cases have also been documented as progressing to necrotizing fasciitis and/or multiple organ system failure. Although such infections can occur in healthy hosts, the most serious cases are in immunocompromised individuals and those who have experienced a mild to severe injury to the infected site. One such case involved a fatal episode of multiple organ dysfunction, only 7 days after a 58-year-old Canadian developed a septicemia with V. In addition, he had suffered a minor wound after handling shellfish that rapidly developed into septic shock. If an enrichment procedure is desired to enhance isolation of vibrios, alkaline peptone water with 1% NaCl (pH 8. It is not, however, approved for use in clinical laboratories for diagnostic testing, Presumptive Identification Several key tests can aid in the initial identification of a Vibrio isolate. Vibrios can be easily confused with other genera, including Aeromonas, Plesiomonas, Pseudomonas and members of the family Enterobacteriaceae. It is important to note that with the halophilic vibrios, it often is necessary to add at least 1% NaCl to most biochemical media to obtain reliable reaction results. Although rapid and semiautomated identification systems contain databases of the more commonly encountered clinical vibrios, they generally are inadequate for accurate identification of these species, particularly those that are less commonly encountered. Even then, the halophilic species might grow poorly, if at all, and they often are confused with other genera, such as Aeromonas. Most authorities advocate identification with conventional biochemicals, supplemented with additional NaCl, if warranted; alternatively, the rapid system identification should be confirmed at a reference laboratory or state public health department laboratory. It is believed, however, that in the future these methods will be replaced with whole genome sequencing. It generally is considered sufficient for most clinical laboratories below the level of reference laboratory simply to screen their presumptive V. Antimicrobial Susceptibility Both Mueller-Hinton agar and broth contain sufficient salt to support the growth of Vibrio spp. The recommended antimicrobial susceptibility testing methods are standardized disk diffusion (Kirby-Bauer) or dilution susceptibility testing methods. Increased resistance from the acquisition of plasmids is relatively uncommon in the United States, but there are reports of multiple resistant strains from Asia and Africa. Because most vibrios grow rather rapidly and are similar to enteric bacteria in many ways, it is often useful for a first Case Check 20. The Case in Point uses the results obtained from these reactions to identify the responsible organism. Definitive Identification Numerous useful biochemical tests aid in the definitive identification of most isolates to the species level. Aeromonads have a seasonal pattern of increased isolation from May through October, reflecting their increased numbers in aquatic environments in the warmer months in the United States. In general, fluoroquinolones alone or the synergistic combination of ciprofloxacin and cefotaxime display excellent in vitro activity against V. Most vibrios are also susceptible to gentamicin, tetracyclines, chloramphenicol (except P. They are frequently isolated from retail produce sources and animal meat products. Aeromonads are responsible for a diverse spectrum of disease syndromes in warm- and coldblooded animals, including fish, reptiles, amphibians, mammals, and humans. However, phylogenetic evidence from molecular studies resulted in the proposal of a separate family, Aeromonadaceae. Currently, more than 27 proposed species and eight subspecies Clinical Manifestations Intestinal Infections the aeromonads are recognized as enteric pathogens, albeit not in the same manner as the more common enteric pathogens Salmonella, Shigella, and V. The level and pattern of virulence is more like the multifactorial patterns of the various E. Therefore screening of stool specimens for the presence of these organisms, followed by further identification to the species level, is appropriate. This is especially true in cases of pediatric diarrhea or in any type of immunocompromised individual. Five diarrheal presentations are observed in patients in whom an Aeromonas has been isolated from their stools: 1. An acute, dysenteric form of diarrhea (similar to shigellosis) with blood and mucus 3. Most cases are self-limiting, but in the pediatric, geriatric, and immunocompromised populations, supportive therapy and antimicrobials are often indicated. Extraintestinal Infections Aeromonads are also responsible for extraintestinal infections; septicemia and wound infections are the most common. They have also been implicated in cases of meningitis, osteomyelitis, pelvic abscesses, otitis, cystitis, endocarditis, peritonitis, cholecystitis, keratitis associated with contact lens wear, and endophthalmitis in healthy and immunocompromised individuals. Wound infection invariably involves a recent traumatic aquatic exposure, such as a boating or fishing accident, and generally occurs on the extremities. The most common presentation is cellulitis, although there have been a few cases of myonecrosis and necrotizing fasciitis and even a rare case of ecthyma gangrenosum associated with sepsis. It appears that the leech Hirudo medicinalis has a symbiotic relationship with this aeromonad species within its gut, wherein the organisms aid in the enzymatic digestion of the blood ingested by the leech. Aeromonad sepsis is one of the most invasive type of Aeromonas infection and similarly has a strong association with the species A. Although the original source of infection is often unknown, it is surmised that it is the gastrointestinal, biliary or, even more rarely, respiratory tract. Laboratory Diagnosis Culture Media Aeromonads grow readily on most media used for routine and stool cultures. Frequently, an extremely strong odor is present, and pigmentation ranges from translucent and white to buff-colored. This is of particular concern because the most commonly isolated species, especially in pediatric cases of diarrhea, is the lactose-fermenting A. However, if such a medium is warranted for detecting chronic cases or asymptomatic carriers, alkaline peptone water is recommended. A positive oxidase distinguishes aeromonads from the family Enterobacteriaceae (except for Plesiomonas shigelloides), and most clinically relevant aeromonads are indole-positive. The presence and type of hemolysis among multiple aeromonad colony types in a single culture often are the only clues to an infection involving more than one species of Aeromonas. Members of the genera Aeromonas, Plesiomonas, and Vibrio have many similar characteristics. A test to separate aeromonads and plesiomonads from most vibrios is determining the ability to grow in the presence of NaCl. Aeromonads and plesiomonads grow well in nutrient broth with 0% NaCl, but not in 6% NaCl.

In an outbreak investigation medications errors pictures cheap kaletra 250mg without a prescription, surface culturing would be needed; however medicine versed order cheapest kaletra and kaletra, such cultures should not be routinely obtained medicine zithromax buy kaletra overnight. The laboratory must be consulted before environmental surface cultures are undertaken to ensure that proper procedures and media are used 6mp medications order kaletra in united states online. The laboratory scientist should be instrumental in the interpretation of the results medicine 5000 increase order 250 mg kaletra overnight delivery. Some of these requirements are federally mandated medications you can take while breastfeeding purchase kaletra line, whereas some may be designated by the state. It is imperative that the laboratory scientist knows which infectious diseases are reportable to what agency and in what time frame they are to be reported. Reporting to Committees and Programs Depending on the setting served by the microbiology laboratory, there may be expectations of reports of infectious diseases to committees in that setting. For example, in an acute care hospital, infection prevention and control committees may expect reports with various types of microbiological information. Annual antibiograms, lists of reportable diseases, pathogens recovered in certain hospital units, isolates recovered from certain sites, and blood culture contamination rates are examples of reports that might be requested. In other settings, physicians may expect periodic updates, including antibiograms and pathogen prevalence. They may expect these to be delineated by office practice, physician, site, or patient type. Those making these requests may be in home health care, extended care, or communal living settings. Schools and businesses might request updated reports especially related to outbreaks that affect their operation. These reports must be tempered by public health needs and individual confidentiality restrictions. Recently insurance companies and community advocacy groups have expressed interest in knowing about infection control rates. Reporting to the Media Among the activities of a microbiology laboratory, discussing microbiology and infection control activities with the media. Media relations for the laboratory should be discussed with the risk management area associated with the laboratory. Media relations represent an educational opportunity that might be investigated before the laboratory scientist speaks to media personnel. Reporting the role of the microbiology laboratory does not stop with providing culture results. Depending on statutory requirements, the laboratory might also be responsible for the reporting of certain infectious diseases to public health jurisdictions. Other groups may expect reports as well, such as committees, persons managing specific programs, and the news media. Reporting to Public Health There is a requirement to report the identification or suspicion of certain infectious diseases to the local, state, or federal public health entities. Seminars, scientific articles and books, computer-based learning, and discussion with the infection control personnel are ways in which laboratory scientists can maintain their knowledge of infection control and laboratory techniques that can aid the infection control program. As new techniques become available or old techniques A3 B C Blastomycosis, histoplasmosis, scabies, staphylococcal skin infections, toxoplasmosis a these are reporting regulations from the Ohio Administrative Code and may vary from state to state. Similar information needs to be provided for others associated with the health care setting and infection control program. These and other questions arise among ancillary health care personnel and the laboratory scientist needs to be prepared to respond. Consultation with the microbiology laboratory often is sought when construction is anticipated. These are some questions that might be addressed by the microbiology laboratory scientist while acting as a consultant to the infection control program. Whether dealing with emerging diseases, such as Zika virus in 2016, or reemerging diseases, such as Rocky Mountain spotted fever, the laboratory must stay closely aligned with the infection control activities in the setting that the laboratory serves. Emerging Pathogens Sometimes infectious agents that have not been previously recognized appear. The laboratory must quickly learn not only how to identify these agents in human infections but also how to collaborate with the infection control program in dealing with these agents in the human population. The educational role of the laboratory once again becomes evident in teaching specimen collection, specimen transport, disinfection, and safety methods. It is likely that the causative agent, Acinetobacter baumannii, was in the hospital environment and was spread among the patients by improper hygiene. The presence of a ventilator in the affected patients bypassed host defenses in the compromised patients. Safety the infection control program affects the microbiology laboratory by emphasizing the need for laboratory safety. As discussed in Chapter 4, safety in the microbiology laboratory encompasses the infection control program. Hand hygiene involves handwashing when hands are soiled or the use of alcohol hand rubs when hands are not soiled. The practice of standard precautions further extends infection control to the microbiology laboratory. Proper disposal of microbiological waste, according to state or local regulations and national guidelines, is another critical component of the infection control program in the microbiology laboratory. All these functions connect the microbiology laboratory safety program and the infection control program. Reemerging Pathogens the reemergence or potential reemergence of pathogens once thought to be eliminated demands collaboration with the infection control program. The pathogens that cause Rocky Mountain spotted fever, anthrax, and plague are agents that clinical microbiologists have learned about but are not often identified by microbiology laboratories. The laboratory scientist must relearn information once thought to be of low importance. Media selection, identification techniques, and safety precautions must all be reexamined and implemented. Interaction with the infection control program strengthens the establishment of prevention and control strategies. Emerging and Reemerging Pathogens With the advent of terrorist activities worldwide, the microbiology laboratory has become an integral part of that area of the infection Response Plans With the potential use of biological agents in terrorism, the development of emergency response plans is paramount. Safety, specimen collection, agent identification, and agent control are components of the response plan to which the laboratory can contribute its input. Whether in everyday activities or activities in response to an outbreak or emerging diseases, the microbiology laboratory and laboratory scientists constitute a critical component of an efficient and successful infection control program. The microbiology laboratory interacts with the infection control program in many different health care settings. Surveillance is important to establish baseline data and recognize the need to investigate potential outbreaks. The microbiology laboratory supports outbreak investigations by providing consultative services, including epidemiologic correlation of isolates. Although infrequently performed, environmental cultures may play a role in outbreak investigation. Microbiology laboratory scientists must recognize their role in providing reports to health departments, committees, the infection control program, and on occasion, the public. The microbiology laboratory must maintain competencies in new techniques and the identification of reemerging and emerging infectious diseases. In anticipation of potential bioterrorism events, the microbiology laboratory must be equipped to participate in emergency preparedness programs. All of the above Microbial pathogens of potential bioterrorism activity include: a. Bacillus anthracis, Escherichia coli, coronaviruses Environmental cultures are usually to be avoided, except in: a. Establishing a case definition, forming and testing a hypothesis, and communicating findings c. Confirming an outbreak exists, calculating an infection rate, and performing serology and culture tests Infection control programs rely on microbiology laboratory support in: a. All of the above the microbiology laboratory interacts with the infection control program by providing: a. Society for Healthcare Epidemiology of America/Association for Professionals in Infection Control/Infectious Diseases Society of America. No official support or endorsement by the Food and Drug Administration is intended or implied. Discuss the appropriate use of the following skin antiseptics in health care settings by health care personnel: handwash or handrub, surgical hand scrub or surgical handrub, and patient preoperative skin preparation. Define and give examples of engineering controls, work practice controls, and personal protective equipment. Discuss the World Health Organization classification of infectious microorganisms by risk group. Given an infectious agent and test procedure, determine the appropriate safety precautions to use to ensure an exposure event does not occur. Describe the components of basic fire safety and electrical safety within the microbiology laboratory. Discuss the special safety considerations that must be addressed in the clinical microbiology laboratory during a possible bioterrorism event. Adams arrived at the clinic, many children were waiting for her, so she immediately began seeing her patients. At one point, she thought about washing her hands, but she felt guilty about coming to work late and did not want to keep her patients waiting any longer. Sentinel laboratories Sporicidal Standard precautions Sterilization Surgical hand scrub Transmission-based precautions Transient biota Work practice controls Disinfection and Sterilization Safety in the laboratory cannot be overemphasized. Risk to an individual increases with the frequency and type of organism and level of contact with the agent, as demonstrated by the Case in Point at the beginning of this chapter. Each laboratory must develop and institute a plan that effectively minimizes exposure to infectious agents. This article provides information on standard disinfection and sterilization techniques and laboratory safety guidelines for the clinical laboratory. To understand fully the principles of disinfection and sterilization, we need to have accurate definitions of certain terms. Sterilization refers to the destruction of all forms of life, including bacterial spores. By definition, there are no degrees of sterilization-it is an all-or-nothing process. Chemical or physical methods may be used to accomplish this form of microbial destruction. For example, a solution that has been filtered through a certain pore-size filter (<0. Disinfection refers to a process that eliminates a defined scope of microorganisms, including some spores. Physical or chemical methods may be used, but most disinfectants are chemical agents applied to inanimate objects. A substance applied to the skin for the purpose of eliminating or reducing the number of bacteria present is referred to as an antiseptic. Factors That Influence the Degree of Killing Before discussing methods used to kill microorganisms, a review of the factors that influence the degree of killing of organisms is important. Microorganisms living together in communities, referred to as biofilms, also provide protection to the microorganisms against chemical and physical means of destruction. The organisms known today to be the most resistant to the actions of heat, chemicals, and radiation are prions. Prions are thought to be the agents that cause a number of degenerative diseases of the nervous system (transmissible spongiform encephalopathy-mad cow disease, Creutzfeldt-Jakob disease). These agents are transmitted to humans through contaminated medicinal products, therapeutic devices, body fluids, and food products. These infectious agents are extremely resistant to chemical and physical methods of destruction. It is best to handle all body secretions as potentially being contaminated with this agent. When an object or material is thought to be contaminated with a prion, special methods need to be taken to destroy the agent. Number of Organisms Another factor to consider is the total number of organisms present, referred to as the microbial load (bioburden). Because the microbial load is most likely composed of organisms with differing degrees of susceptibility to killing agents, not all the organisms die at the same time. This variability is due to the biochemical composition of microorganisms and various mechanisms that they can use to protect themselves. For example, bacterial endospores have coats rich in proteins, lipids, and carbohydrates as well as cores rich in dipicolinic acid and calcium, all of which protect the spores. Cell walls of mycobacteria are rich in lipids, which may account for their resistance to chemical and environmental stresses, particularly desiccation. In contrast, Concentration of Disinfecting Agent the concentration of a disinfecting agent is also important.

Young Actinomyces colonies are frequently spider like or wooly medicine 2 discount 250 mg kaletra otc, whereas older colonies of A symptoms yeast infection women cheap 250mg kaletra fast delivery. Depending on the species medicine in the civil war buy kaletra online now, colonies may be red medicine 2 times a day purchase kaletra 250mg overnight delivery, pink medicine names generic kaletra 250 mg on-line, tan treatment integrity cheap kaletra online amex, yellow, white, or grayish. The ends of the cells may be pointed, bent, club-shaped, spatulated, or bifurcated (forked). Cells may appear singly or in chains and as starlike aggregates, V arrangements, or palisade clusters. Others have been described as medium in size, with a rough appearance and gray color. Lactobacilli are catalase negative and, unless a Gram stain is performed, differentiation from Streptococcus sp. A gram-positive anaerobic diphtheroid that is both catalase and spot indole positive can be presumptively identified as C. This organism ranges considerably in size and shape, ranging from coccoid and short diphtheroidal rods to long, branched filaments. As the genus name implies, propionic acid is a major metabolic end product of Propionibacterium spp. Identification of Anaerobic Gram-Negative Bacilli Key tests for the identification of gram-negative anaerobic bacilli are listed in Table 22. The genus Bacteroides was divided previously into bile-tolerant and bile-sensitive species. However, most of the bile-sensitive species were transferred to the genera Prevotella and Porphyromonas. The originally pale yellow medium turns brown to black in the area around the colonies. Good growth is the result of bile tolerance, and darkening of the medium is caused by esculin hydrolysis. A dark precipitate (stippling) in the medium around the areas of heavy growth is suggestive of the species B. Depending on the commercial source, age, and storage conditions of the medium, other organisms, such as F. Their colony size (which tends to be smaller), Gram stain morphology, and aerotolerance will aid in the recognition of these other organisms. All members will be resistant to colistin, kanamycin, and vancomycin special potency disks. Some species of Prevotella produce protoporphyrin, a dark pigment that causes their colonies to become brown to black with age. Only brick red fluorescence allows presumptive identification of the pigmented Prevotella group. Campylobacter ureolyticus Group the Campylobacter ureolyticus group consists of bile-sensitive and bile-tolerant nonpigmented organisms (see Table 22. However, not all strains actually pit agar, and among those strains that do, not all colonies will appear to be pitting, so they may resemble a mixed culture. Growth in broth is enhanced by the addition of formate or fumarate, a characteristic unique to this group. Fusobacteria are resistant to vancomycin but susceptible to colistin and kanamycin with the special potency disks. Phenotypic characteristics used to identify anaerobic cocci are listed in Table 22. As noted, presumptive identification of gram-positive anaerobic cocci can be reported as Peptostreptococcus spp. A black-pigmented, anaerobic, gram-positive coccus can be identified as Peptococcus niger. Finegoldia magna and Parvimonas micra are similar in biochemical reactions but can be differentiated on the basis of size; F. It is also positive for nitrate reduction and is resistant to the vancomycin special potency disk. As a result, when physicians suspect an anaerobic infection, they routinely select a broad-spectrum agent for empiric therapy that will cover most anaerobes, pending outcome of the culture. This practice was based on the fact that many antimicrobial agents could be relied on to have good activity against the most commonly isolated anaerobes. However, resistance to antimicrobial agents has increased in recent years, and the susceptibility patterns of many anaerobes to certain antimicrobial agents can no longer be guaranteed. Problems in Susceptibility Testing of Anaerobic Isolates Several problems have limited the routine susceptibility testing of anaerobes, including a lack of reproducibility, failure of some anaerobes to grow on or in particular media, difficulty in reading end points with certain methods, and a lack of comparability between methods. Although it is considered the gold standard method, agar dilution is labor-intensive and is not a practical method for use in smaller clinical laboratories. It is used primarily in reference laboratories and institutions that test large numbers of isolates. Broth microdilution panels are commercially available and can be stored frozen or lyophilized for extended periods. Testing can be performed on Mueller-Hinton agar supplemented with 5% sheep red blood cells, and plates can be incubated in anaerobe bags, jars, or chambers. Testing is limited to six antimicrobial agents on one agar plate, which is usually sufficient for most clinical situations. One critical aspect of the Etest procedure is limiting exposure to oxygen during setup and quickly achieving anaerobiasis. This is because the commonly used antimicrobial agent metronidazole is very oxygen sensitive. Many laboratories amend their anaerobic culture reports with statements suggesting empiric agents that continue to have broad anaerobic activity. This provides physicians with valuable information about the empiric treatment of anaerobic infections. Although antimicrobial resistance has been observed with almost every agent known to have anaerobic coverage, the carbapenems, metronidazole, and the -lactam combination antibiotics continue to have activity against most anaerobes and are used as empiric therapy. Antimicrobial treatment of necrotic abscess is difficult because of poor circulation to the infected site. Antitoxins In cases of tetanus and botulism, antitoxins are used to neutralize the effect of neurotoxins produced by C. Antitoxins are affective against toxin molecules that have not yet bound to host cell receptors. Although the technique sounds unpleasant, the cure rate of fecal microbiota transplant is over 90% in patients in whom numerous treatments with antimicrobials. Treatment of Anaerobe-Associated Diseases There are essentially five approaches to the management of anaerobic infections. Points to Remember Surgical Therapy Because most anaerobic infections are abscesses caused by mixtures of aerobic and anaerobic bacteria, the most important therapy is surgical drainage of the abscess. Other surgical procedures include removing dead tissue (debridement), eliminating obstructions, decompressing tissues, releasing trapped gas, and improving circulation in, and oxygenation of, tissues. Hyperbaric Oxygen the use of a hyperbaric oxygen chamber to force oxygen into necrotic tissue has been used as adjunct therapy for anaerobic infections for many years and has gained popularity in specialty wound care clinics. Hyperbaric oxygen has also been suggested to be useful therapy for cases of osteomyelitis caused by anaerobes. Antimicrobial Therapy the primary role of antimicrobial agents is to limit the local and systemic spread of the organisms. Selection of the correct antimicrobial agent depends on a number of factors, including types Anaerobes are organisms that do not require oxygen for life. Anaerobes are important in human and veterinary medicine because they can produce serious and often fatal infections and intoxications. Anaerobic infections of exogenous origin are usually caused by grampositive, spore-forming bacilli belonging to the genus Clostridium. The anaerobes most frequently isolated from infectious processes in humans are those of endogenous origin, such as members of the B. Factors that commonly predispose the human body to anaerobic infections include trauma of mucous membranes or skin, vascular stasis, tissue necrosis, and decrease in the redox potential of tissue. Significant clinical infections caused by anaerobes include mixed microbiota abscesses, tetanus, botulism, myonecrosis, antibioticassociated diarrhea, and actinomycosis. Many types of specimens are unacceptable for anaerobic bacteriology because they are likely to be contaminated with anaerobes of the endogenous microbiota. Proper selection, collection, and transport of specimens for anaerobic culture are critical for quality results and maximum recovery of pathogens. The anaerobes most commonly associated with infectious processes and those most often isolated from specimens include members of the B. Susceptibility testing of anaerobes is not recommended for all anaerobic isolates but is warranted for specific types of serious infections and whenever especially virulent or drug-resistant anaerobes have been isolated. Practical methods for anaerobe susceptibility testing include microwell broth dilution panels and the Etest. Anaerobe-associated diseases may be treated by surgery, hyperbaric oxygen therapy, antitoxins, and antimicrobial therapy. Match the following infectious diseases with their associated causative organism: Myonecrosis Tetanus Botulism Pseudomembranous colitis Actinomycosis a. An organism that can live in reduced concentrations of oxygen but prefers an anaerobic environment is known as a(n): a. Some anaerobes are particularly susceptible to oxygen because they lack the enzyme: a. A gram-positive bacillus was isolated from a wound specimen and had the following characteristics: double zone of -hemolysis, lecithinase positive, lipase negative, spot indole negative. An anaerobic, pleomorphic, gram-negative bacillus was recovered from a liver abscess. The special potency antimicrobial disks demonstrated that the organism was vancomycin resistant and colistin and kanamycin sensitive. Other results were as follows: chartreuse fluorescence, spot indole positive, and lipase positive. Fusobacterium varium Indicate whether the following statements are true or false: 8. Exogenous anaerobes more commonly cause infectious diseases than endogenous anaerobes. Failure to isolate fusiform gram-negative organisms that were observed on a Gram-stained smear of a clinical specimen could be an indication that a problem exists with the primary medium used for the isolation of anaerobes or the system being used for anaerobic incubation of primary plates. A pleomorphic gram-positive bacillus that is spot indole and catalase positive can be presumptively identified as Cutibacterium acnes. Morbidity and Mortality Weekly Report, Notifiable Diseases and Mortality Tables Weekly, 65(30), 1. Methods for antimicrobial susceptibility testing of anaerobic bacteria: approved standard (ed. Principles and procedure for detection of anaerobes in clinical specimens: approved guideline. Bacteroides, Porphyromonas, Prevotella, Fusobacterium, and other anaerobic gram-negative rods. Laboratory survey and literature review of anaerobic bacteriology: foundations of a clinically oriented and evidence-based workup for anaerobic bacteriology. Peptostreptococcus, Finegoldia, Anaerococcus, Peptoniphilus, Veillonella, and other anaerobic cocci. Compare the causative agents and arthropod vectors of relapsing fever and Lyme disease. Describe the laboratory diagnosis of relapsing fever and how it differs from the diagnosis of other spirochete diseases in the United States. Describe the clinical manifestations of the primary, secondary, and tertiary stages of syphilis. Evaluate the tests used to diagnose Treponema pallidum infections in the clinical laboratory. Case in Point A 29-year-old man arrived at a local medical clinic in Los Angeles complaining of diarrhea, fever, chills, muscle aches, and headaches. He had returned 2 days earlier after competing in the EcoChallenge in Malaysian Borneo. During the competition, he had completed various events, including mountain biking, caving, climbing, jungle trekking, swimming, and kayaking in freshwater and salt water. He was still recovering from multiple abrasions from the jungle trekking and mountain biking. While kayaking the Segama River, his kayak had capsized and he had inadvertently swallowed several mouthfuls of river water. His two teammates were took doxycycline as malaria prophylaxis before and during the race. The family Leptospiraceae contains the genus Leptospira, and the family Spirochaetaceae contains the genera Borrelia and Treponema. These three genera include the causative agents of important human diseases, such as syphilis (sexually transmitted); zoonoses (transmitted from animals to humans), such as leptospirosis; and vector-borne diseases, such as Lyme disease (or Lyme borreliosis) and relapsing fever. Spirochetes are slender, flexuous, helically shaped, unicellular bacteria ranging in size from 0.

The inclination to exchange genes increases concern about the possible spread of drug resistance determinants from commensal or nonclinical organisms in animals and humans to human pathogens treatment yeast diaper rash order 250 mg kaletra mastercard. Integrons can be chromosomally encoded and are not independently mobile; however symptoms webmd kaletra 250mg amex, they are usually mobilized on plasmids and Tns medications gabapentin kaletra 250 mg. Genetic analysis revealed the presence of a multiresistant conjugative plasmid harboring Tn1546 (VanA) treatment 8mm kidney stone kaletra 250 mg fast delivery. A Tn1546-like transposable genetic element encoding for transposition treatment upper respiratory infection kaletra 250 mg discount, regulation of VanA expression medications ibs generic kaletra 250 mg with visa, and resistance is also found in enterococci. The data suggest that the interspecies transfer of Tn1546 occurs from a coresident isolate of E. Resistance to vancomycin can be spread by the transposition of 1547 to a conjugative plasmid and transferred by conjugation to recipient strains or by excision and circularization of the Tns, followed by conjugation. On subsequent infection, those resistance determinants may be transferred to the infected bacterium. Nanotechnology to Deliver Therapeutic Agents Nanoparticles are less than 100 nm in size and have unique biological, physical, and chemical properties at these dimensions. The nanomaterial can be loaded with drugs, biomolecular diagnostic tools, and contrast agents that can help to locate the agents and understand their action in real time. These tools can help us to understand the mechanisms of drug resistance more accurately. In many cases, the unique properties of nanomaterial facilitate the fast diffusion of the drug to the infection, which can significantly enhance treatment. Nanomedicine is being tested as a way to deliver various therapeutic drugs to tissue. Nanoencapsulation delivery systems are used to increase the circulation time of drugs, which allows the drugs to reach their destination in the body without degradation. Nanoencapsulation can increase the solubility and improve the pharmacokinetic profiles of insoluble drugs, and in many cases, targeted drug delivery greatly enhances the bioavailability to the target tissues. Encapsulating the drug allows more surface modification, and encapsulated ingredients can be stabilized for longer periods. Several nanoparticle-based drug delivery systems are approved for clinical use to treat a variety of infectious diseases. Bacterial infections are known to trigger inflammatory reactions that can stimulate vascular permeability. The increased permeability and dysfunctional lymphatic drainage has been shown to facilitate the accumulation of drug-loaded nanoparticles at the infection site. Under physiological conditions, pathogenic bacteria have a negative surface charge. Cationic nanoparticles are capable of binding to bacteria by electrostatic interactions. Nanoparticles also have been coated with ligands that bind specifically to bacterial receptors. To reach intracellular bacteria, nanoparticles have been coated with ligands binding to macrophage receptors. A difficulty with this strategy is the differing pharmokinetics, biodistribution, and membrane-penetrating properties of different drugs. This therapeutic strategy has been shown to be more effective in treating tuberculosis compared with free drugs at the same dosage. Nanoparticle delivery systems include liposomes, polymeric nanoparticles, and dendrimers. Liposomes are closed, continuous bilayered structures of synthesized polymers that can be used for nanoencapsulation. In the liposome artificial membrane, sometimes under specific conditions, small closed vesicles can be formed that make up a lipid bilayer. Nanoshells are about 5 to 10 times smaller than liposomes, with a pore size of around 2 nm. Nanoshells consist of vesicular porous structures that allow them to be effective in targeting the drug, They are synthesized from silica or calcium phosphate. Nanoshells are biodegradable and trap the drugs in the interior space, actively targeting the drug site. The toxicity levels for nanoshells are lower than for other delivery systems but are subject to further investigation. These are small, stable lipid structures composed of a bilayer sheet that is rolled up into a spiral-like structure. The benefits of this structure are that cochleates have higher stability, and they can deliver drugs to negatively and positively charged species. Points to Remember Although resistance to antimicrobial agents may be genetically intrinsic or acquired, both types can be found in the same pathogen. Protein inhibitors include aminoglycosides, tetracyclines, macrolides, streptogramins, chloramphenicol, and linezolid. Impermeability and efflux mechanism of resistance can produce multidrug-resistant phenotypes. A single organism may acquire multiple mechanisms of resistance, including different mechanisms of conferring resistance to the same compound. Antimicrobial mechanisms of resistance and their dissemination are not static processes. Nanoparticles are being used to deliver various drugs, including antimicrobial agents, into tissue. Microorganisms can exhibit antimicrobial resistance by which of the following mechanisms Which of the following does not apply to antimicrobial resistance caused by target site modification Enzymatic modification of aminoglycosides is not caused by which of the following Serine-based -lactamases appear to have evolved from the penicillin-binding proteins of bacteria. Which one of the following antimicrobials acts predominantly on cell membrane integrity White paper: developing antimicrobial drugs for resistant pathogens: narrow spectrum indications and unmet needs. Membrane permeability and regulation of drug "influx and efflux" in enterobacterial pathogens. Loss of outer membrane protein C in Escherichia coli contributes to both antibiotic resistance and escaping antibody-dependent bactericidal activity. A novel hybrid plasmid carrying multiple antimicrobial resistance and virulence genes in Salmonella enterica serovars Dublin. The porin and the permeating antibiotic: a selective diffusion barrier in gram-negative bacteria. Antibiotic resistance in the absence of antimicrobial use: mechanisms and implications. Fluoroquinolone resistance: mechanisms, impact on bacteria, and role in evolutionary success. Functional studies of cochleate assemblies of an oligo-acyl-lysyl with lipid mixtures for combating bacterial multidrug resistance. Methicillin-resistant Staphylococcus aureus infection with intermediate sensitivity to vancomycin: a case report and literature review. The increasing spread of colistin resistance is resulting in untreatable infections. Gene flow, mobile genetic elements and the recruitment of antibiotic resistance genes into gram-negative pathogens. Loss of methyl transferase function and increased efflux activity leads to doxycycline resistance in Burkholderia pseudomallei. Multiresistant gram-negative bacteria: the role of high risk clones in the dissemination of antibiotic resistance. Explain the rationale behind the performance of antimicrobial susceptibility tests. Explain how zone interpretive criteria used with the disk diffusion test are established. List the variables that must be controlled when antimicrobial susceptibility tests are performed. Describe test modifications for antimicrobial susceptibility testing of Helicobacter/Campylobacter spp. Explain the principles behind automated antimicrobial susceptibility test methods. Discuss several commercially available antimicrobial susceptibility test systems in current use. Explain the reliable methods for detection of methicillin-resistant Staphylococcus aureus, vancomycin-intermediate S. Explain extended-spectrum -lactamases and carbapenemases, and how organisms that produce these enzymes are detected in the clinical laboratory. Describe how antibiograms can be used to help verify the accuracy of results generated by testing patient isolates. Discuss situations in which cumulative antibiograms may help to guide antimicrobial therapy. Explain the meanings of nonsusceptible, susceptible, intermediate, and resistant as applied to antimicrobial susceptibility test results. Explain the role of matrix-assisted laser desorption/ionization mass spectrometry in determining the susceptibility of bacteria to antimicrobials. Define synergism, antagonism, and indifference as related to testing combinations of antimicrobial agents. Describe the serum bactericidal test, and list the indications for performing this test. Discuss methods used for measuring concentrations of antimicrobial agents in serum and body fluids, and indicate when such tests are used. Case in Point the microbiology laboratory supervisor was reviewing patient reports that the floating technologist had generated earlier in the day. She went to the technologist and reminded her of the special testing methods and reporting rules, and the technologist corrected and rereleased the report, which was as follows: cefazolin-R, cefoxitin R, clindamycin-R, erythromycin-R, oxacillin-R, penicillin-R, and vancomycin-S. Only organisms that are likely to be contributing to an infection should be tested. Testing organisms that are not involved in an infection is misleading to the physician and could lead to a more serious infection with development of antimicrobial resistance. One of the major purposes of the clinical microbiology laboratory is to identify organisms that are the cause of infections. Often, these organisms need to be distinguished from the normal microbiota that may reside at the site of the infection, although in some situations the microbiota that reside at the site of the infection may be contributing to the infection. Therefore, thought needs to go into determining which organisms, from a specimen will be tested for susceptibility to antimicrobials. Most microbiology laboratories have guidelines for determining when and on which microorganism susceptibility testing will be done. Publication as an International Standard requires approval by at least 75% of the member bodies casting a vote. In all cases, it is important to maintain an awareness of which antimicrobial agents are appropriate to test, the reliability of various test systems for detecting antimicrobial resistance, and strategies for effectively communicating results on laboratory reports to those who need to be informed. Such adjustments include discontinuing the use of the drug for a time, reserving use of the drug for specific patients, using the drug in combination with another, and generally using an antimicrobial of a different class to treat infections caused by that bacterium. For example, Escherichia coli is normal microbiota in the lower gastrointestinal tract and therefore, would not be tested when isolated from stool. Similarly, viridans group streptococci represent normal microbiota in throat specimens and would not be routinely tested. Coagulase-negative staphylococci isolated from multiple blood cultures would be tested; but because coagulase-negative staphylococci are commonly found on skin surfaces, these bacteria would not be tested when isolated from superficial wound specimens. Yeasts isolated in low numbers in vaginal specimens or in the throat, if other microbiota is present, would not be considered significant. Presence of Other Bacteria and Quality of Specimen the isolation of an organism in pure culture is less likely to represent contamination than a mixed culture. A few Klebsiella pneumoniae organisms in the presence of oropharyngeal flora in a sputum culture may not be significant. In the absence of oropharyngeal flora, however, a few colonies of this species, particularly if noted on a Gram stain of the sputum, may be significant and warrant susceptibility testing. Host Status the host status of the patient often influences susceptibility testing decisions. Species usually viewed as normal microbiota might be responsible for an infection and therefore may require testing in an immunocompromised patient. Although information can be determined on the susceptibility of specific bacteria from the literature, there may be differences at a specific health care facility. Susceptibility tests are not performed on bacteria that are predictably susceptible to the antimicrobial agents commonly used to treat infections caused by these bacteria. Group A -hemolytic Streptococcus, for example, is not routinely tested because it is universally susceptible to penicillin, the drug of choice in treating infections caused by this bacterium. In contrast, the recommended agent for treating Staphylococcus aureus infections is oxacillin, but not all S. Susceptibility testing of isolates can also provide information on decreases in the susceptibility of bacteria to antimicrobials. When that value is achieved, it triggers a concern that the bacterium is developing resistance to the antimicrobial. Each laboratory must determine which agents are appropriate for routine testing against various organisms (or organism groups) in its setting. Laboratory workers should not formulate testing and reporting protocols without input from drug prescribers. It is important that the drugs tested by the laboratory match the institutional formulary as closely as possible. From the laboratory perspective, the limiting factor for the number of drugs tested is usually the number that can be practically tested with a specific method.

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