The CLSI method specifies the use of control strains including B. fragilis ATCC 25285, Bacteroides thetaiotaomicron ATCC 29741, and Clostridium difficile ATCC 700057. and other Gram-negative organisms as anaerobic pathogens. Dogs that have developed an anaerobic bacterial infection because of a wound, for instance, may display bite marks, have pus oozing from the wound, or open fractures (where bone sticks out). Resistance to P. acnes has been related to previous use (127). express enzymes that are generally inhibited by clavulanic acid (110). Most hospitals that send strains out for susceptibility testing are getting test results by using Etest methodology, which is within the expertise available in most hospitals. The decline in the number of hospital laboratories performing anaerobic susceptibility tests during exactly the same time period that more multidrug-resistant strains of anaerobes are being found in serious infections is problematic. When used in combination with a beta-lactam antibiotic (such as ampicillin-sulbactam, amoxicillin-clavulanate, and piperacillin-tazobactam), they are effective in treating anaerobic infections caused by beta-lactamase-producing bacteria (BLPB). The most commonly isolated antibiotic-resistant anaerobes are species within the Bacteroides fragilis group (18). 48). Details of the procedure are described in the manufacturer's guidelines. protozoans, bacteria) or multicellular. This implies that these species can also grow in parts of the human body wherein the amount of oxygen supplied is very low. Other antimicrobials, such as doxycycline and minocycline, are more effective than tetracycline. The tolerance of metronidazole in patients is generally very good. Clin Infect Dis. A classification based on amino acid sequence was created by Ambler (102), and a classification based upon substrate-of-inhibition profiles, molecular weight, and isoelectric points was proposed by Richmond and Sykes (103). (113). Many reference laboratories will use commercially prepared panels; in these cases, the agents tested will depend on whichever antibiotics are included in the commercial panel that the laboratories are using for testing. Etest (AB Biodisk). At that time, technical variability among laboratories was a major factor. Author information: (1)Istanbul Technical University, Environmental Engineering Department, Maslak, Istanbul, Turkey. Each individual cephalosporin may have either a class or specific inhibitor enzyme that is able to inactivate it. (33) observed that 90% of B. fragilis isolates recovered from nosocomial infections and bacteremias in Taiwan were susceptible to moxifloxacin. Activity of a novel carbapenem, doripenem, against anaerobic pathogens. All this suggests that clinicians rely on “FDA indications, information from the manufacturers supplied by drug reps, published study/survey data or just make an educated guess at the appropriate empirical or directed therapy” (20). Once thought harmless commensals, anaerobes are now implicated in many human eye infections. Clinical experience with penicillin G in the management of susceptible anaerobic bacterial infections has been good. The Etest is particularly suitable for testing of one or a few isolates against multiple agents (as long as the particular agent is available on an Etest strip). The source of isolates (i.e., stool, abscess, or appendiceal) may also influence the resistance profile of the species and should be considered when evaluating the survey results. Two recent studies used matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) to identify B. fragilis strains that carry the cfiA gene; these strains are restricted to division II type strains (60, 61). South Afr J Epidemiol Infect. Obligate anaerobes, together with microaerophils, are characterized by their sensitivity to oxygen. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp. Other experiments (130) have shown that administration of metronidazole to rats and hamsters does not induce any pathology. Most Clostridium strains (with the exception of some strains of Clostridium ramosum, Clostridium clostridioforme, and Clostridium innocuum) and Peptostreptococcus spp. Antimicrobial resistance among anaerobes has consistently increased in the past decades, and the susceptibility of anaerobic bacteria to antimicrobial agents has become less predictable. NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. Resistance has also increased for many non-Bacteroides anaerobes. Despite the emergence of carbapenemase-resistant Enterobacteriaceae, it is also effective against most Enterobacteriaceae, with about 5% to 15% of Pseudomonas species strains being resistant (95). While aerobes are able to thrive in habitats that have abundant oxygen, anaerobes may die in the presence of oxygen. Pathogenic gram-positive bacteria If a bacterium is pathogenic, it means it causes disease in humans. Bacteroides multidrug efflux [Bme] pumps 1 to 16) and are apparently important in conferring multidrug resistance (23, 65, 68); pump activity related to resistance has also been described for Clostridium (69 The production of BLAs is the most common mechanism of resistance to β-lactam antibiotics in anaerobes, especially among the B. fragilis group and Prevotella spp. However, with the reemergence of anaerobic bacteremia in the 1990s, many centers resumed processing of blood cultures for anaerobes. Anaerobic Bacteria: Anaerobic bacteria live in oxygen-depleted areas such as digestive system (stomach to the rectum) of animals. Therefore, in the case of single isolates, it is useful for the clinician to know the MIC of a drug for the strain as well as the established breakpoint rather than just the categorical determination. These nim genes were found in 50/206 (24%) Bacteroides species isolates and resulted in MICs of 1.5 to >256 μg/ml for metronidazole, including 16 isolates with MICs of ≥32 μg/ml (54). The combinations of BL-BLICs and carbapenems have maintained their excellent antibacterial activity. Sometimes, these agents are used for surgical prophylaxis for abdominal surgery and for the treatment of aspiration pneumonia. and Porphyromonas spp. The major concerns with expanding the use of fluoroquinolones to treat anaerobic infections have been reports of increasing resistance in strains of the B. fragilis group as well as anaerobic Gram-positive cocci and the impact of these antibiotics on the growing incidence of C. difficile-associated disease (142). A broth-dilution method for performing antimicrobial susceptibility tests on anaerobic bacteria has been proposed. It has often been used for surgical prophylaxis at most body sites that are in proximity to mucus membranes. (137), who tested 396 unusual anaerobes, found all Gram-positive anaerobes and 228/232 Gram-negative anaerobes to be susceptible to ≤1 μg/ml of tigecycline. Assessment of anaerobic bacterial diversity and its effects on anaerobic system stability and the occurrence of antibiotic resistance genes. Most studies conform to CLSI breakpoints, but certain EUCAST breakpoints are different. They are less effective against Fusobacterium and Peptostreptococcus spp. protozoans, bacteria) or multicellular. Two recent reports have noted the development of some carbapenem resistance among anaerobes (22), ranging from 1.1 to 2.5% in a multicenter U.S. survey but with a higher rate for a small number of isolates from Taiwan (33). However, cefoxitin has poor activity against B. thetaiotaomicron isolates. Consequently, the most likely agents to cover the vast majority of anaerobes encountered in mixed infections will be either a carbapenem or a BL-BLIC such as piperacillin-tazobactam. Antimicrobial susceptibility profiles of anaerobes from different countries. A multicenter survey (93) found penicillin resistance for Fusobacterium spp., Porphyromonas spp., and Peptostreptococcus spp. B. fragilis group resistance rates for piperacillin-tazobactam are generally <1% (27). Up to 10% resistance was noted for Prevotella spp., Fusobacterium spp., Porphyromonas spp., and Peptostreptococcus spp., with higher rates for some Clostridium spp. Listeria bacteria are anaerobic, while Corynebacterium are aerobic. Antibiotic prescribed will depend on the kind of infection, and the causative bacteria. 15). This book is appropriate for advanced undergraduate students of micro biology and biological sciences in universities and colleges, as well as for research workers entering the field and requiring a broad contemporary view of anaerobic bacteria and associated concepts. Focus Diagnostics (also a subsidiary of Quest Diagnostics, Inc.) has discontinued the microdilution test for anaerobic testing and now offers routine testing using Etest (anaerobic susceptibility panel 51477). However, these agents have improved activity against Enterobacteriaceae. fragilis group species, and resistance to them is generally low, except that more than half of Prevotella species isolates may also produce BLAs. A prospective study of Bacteroides bacteremia reported adverse clinical outcomes for 128 individuals who received an antibiotic to which the organism was not susceptible (14). At least 50 to 100 strains should be tested in order to obtain an accurate picture of the pattern of local isolates, and if isolates from different body sites are available, they should be included. Antibiotics are used for treatment or prevention of bacterial infection. Although these enzymes are generally chromosomally mediated, a plasmid-mediated metallo-BL has been reported in Japan (108). Aerobic Bacteria: Aerobic bacteria live in the soil, water, and on different surfaces. Anaerobic infections are usually treated with antibiotics and other medications. Many anaerobes possess cephalosporinases, and therefore, as a class, cephalosporins have very limited utility (41). Amplification was done with a set of primers designed for detecting five resistance genes, including carbapenems (cfiA), cephalosporins (cepA), clindamycin (ermF), metronidazole (nimA-F), and tetracycline (tetQ), plus a set of primers for the B. fragilis 16S rRNA gene (positive control). Cefoxitin is therefore the most effective cephalosporin against the B. fragilis group. Selection of antimicrobial agents is simplified when a reliable culture result is available. (3) Results: In our database of 1719 patients, 365 patients had microbial testing, of which 42 grew anaerobic bacteria. Some antimicrobials have a limited range of activity. Currently, we are not aware of any commercially available ready-made broth microdilution panels that are “FDA approved” for clinical diagnostic use. There is also a frozen panel that was previously sold by Remel (ANA MIC panel, catalog number R8320100), now marketed through Oxoid; this can be ordered in the United States through ThermoFisher (it is shipped from the United Kingdom and requires a lead time of 4 to 6 weeks). Most susceptibility studies emanating from European countries use CLSI methodology, although breakpoint interpretation is often based on EUCAST recommendations, and differences in reported resistance rates may be due to differences in breakpoint determination. Antibiotic stewardship personnel should review this practice. The carbapenems (imipenem, meropenem, doripenem, and ertapenem) have excellent activity against anaerobes (92). In B. fragilis, 16 homologs of tripartite efflux pumps of the resistance nodulation division (RND) family have been described ( Moxifloxacin achieved similar clinical success rates against all anaerobes, including those isolated from patients infected with B. fragilis (158 [82.7%] of 191 patients), B. thetaiotaomicron (74 [82.2%] of 90 patients), and Clostridium spp. There is evidence that suboptimal therapy can actually select for antibiotic resistance and even induce transfer of resistance determinants. It is used for dental infections, especially in patients who are allergic to penicillin, and for aspiration pneumonia. A 2008 survey of clinical hospital laboratories (20) revealed that fewer than half of the laboratories did any kind of anaerobic testing at all, either in-house or any kind of batch testing sent to an outside laboratory. At least in aerobes, much of the multidrug resistance seen in the last several years is due to the action of multidrug efflux pumps, and we have indications that a similar phenomenon may be operative in anaerobes as well. Anaerobes from outside the body sometimes cause disease when they enter breaks in the skin or are consumed. Find this and other Microbiology standards in the CLSI Shop. The CLSI reference standard is not intended for testing of single isolates; rather, it provides a standard against which other methods may be measured. In practice, most hospitals that use microbroth panels order the panels that reflect the needs of their physicians based on hospital formulary and drug used and not on FDA approval. Since that time, the CLSI (formerly NCCLS) procedures have been extensively revised and have been adopted by virtually all testing laboratories in the United States and even worldwide. Depending on the cause of the anaerobic infection, dogs may display a variety of symptoms. Wexler et al. Azithromycin is, in general, the most active macrolide against AGNB such as Fusobacterium spp., Bacteroides spp., Wolinella spp., and Actinobacillus actinomycetemcomitans, including strains resistant to erythromycin. Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms that form part of the normal endogenous flora of man. Although not all cfiA-positive B. fragilis strains are resistant to carbapenems, they all have the possibility of becoming resistant to this group of antibiotics by acquisition of an appropriate insertion sequence (IS) element for full expression of the cfiA gene, leading to possible treatment failure. Recommend to perform this kind of study on a regular basis. The plate for which the growth is no longer present should be considered the MIC. Consequently, when asked, most clinicians will consider the presence and role of B. fragilis in an infectious process and will likely lump all other anaerobes into the single category of “other anaerobes.” This narrowed view is also a result of current schemas of limited laboratory identification and reporting of anaerobes. Carbapenemases are active against the carbapenems as well as all β-lactam antibiotics. Moxifloxacin has been approved by the FDA for the treatment of complicated skin and skin structure infections, including those due to B. fragilis, and for mixed intra-abdominal infections caused by B. fragilis, B. thetaiotaomicron, Peptostreptococcus spp., and C. perfringens. 91). The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. For example, within the B. fragilis group, MICs for B. thetaiotaomicron and B. ovatus are often higher than those for B. fragilis. In contrast, MICs for Pseudomonas and Proteus spp. Both Argentina (31) and Japan have published testing methods, but these are closely based on CLSI methodology. 10:55-59. The nonteratogenicity of metronidazole is difficult to prove, but the existing available data indicate no major risks and no indication for the termination of pregnancies (134). (27) observed that 5% of B. fragilis, 3.6% of B. thetaiotaomicron, 3.3% of B. ovatus, and 7.2% of the unusual B. fragilis group species isolates showed resistance to tigecycline. Agents to test should include those on the hospital formulary, and the agent that is being considered or used for therapy should be included if at all possible. Antibiotic Susceptibility Bacterial Susceptibility Testing (1 test) MIC Test, Anaerobic Bacteria Susceptibility Testing Minimum Inhibitory Concentration (MIC) Clindamycin Ertapenem Metronidazole Minocycline Moxifloxacin Penicillin Piperacillin-tazobactam Amoxicillin-clavulanate Cefotaxime Ceftriaxone Ciprofloxacin Meropenem Vancomycin Actinobaculum Actinomyces Anaerococcus … These include mainly diabetic foot and intra-abdominal infections and aspiration pneumonia. In the past, he has served as an Associate Editor for Clinical Infectious Diseases and the Journal of Medical Microbiology. Aerobic bacteria need oxygen and anaerobic bacteria do not. Bacteroides species resistance to fluoroquinolones has been attributed to either an alteration in efflux of the antibiotic or a mutation in the quinolone resistance-determining region (QRDR) of the gyrase A gene (gyrA) from single or multiple mutations (144). Community-acquired anaerobic bacteremia in adults: one-year experience in a medical center, Antimicrobial resistance and clinical outcome of, Clinical significance and outcome of anaerobic bacteremia, Susceptibility test methods: anaerobic bacteria, Clinical and Laboratory Standards Institute, Methods for antimicrobial susceptibility testing of anaerobic bacteria. 17). (14). Agar dilution technique. For the treatment of anaerobic infections, the clinician will likely choose an antimicrobial therapy empirically and continue that agent as definitive therapy because specific anaerobic microbiological data will not be forthcoming. – Liu et al. Therefore, antibiotic susceptibility testing is not performed and treatment of patients suffering from an infection in which anaerobic bacteria are involved is often empirical. 4, left). However, little clinical experience been gained in the treatment of anaerobic bacteria using these agents. are almost uniformly resistant (128). Carbapenem resistance occurs in <1% of U.S. isolates, and up to 3% of Bacteroides strains harbor one of the genes that is expressed at a very low level. Imipenem has more activity than meropenem against staphylococci and enterococci, but meropenem provides better coverage of aerobic and facultative Gram-negative bacteria such as Pseudomonas, Enterobacter, Klebsiella, Providencia, Morganella, Aeromonas, Alcaligenes, Moraxella, Kingella, Actinobacillus, Pasteurella, and Haemophilus spp. Meropenem is a carbapenem antibiotic that has a very broad spectrum of activity against aerobic and anaerobic bacteria, similar to that of imipenem. The mechanism of metronidazole resistance for non-Bacteroides anaerobes is unknown. Approximately 20% of Clostridium ramosum strains are resistant to clindamycin, as are a smaller number of C. perfringens strains. Gram-positive anaerobic cocci (GPAC) which are commonly known as Peptococci or Peptostreptococci belong to the genus Peptostreptococcus. The potential for growing resistance of anaerobes to antimicrobials is especially noted with penicillins, fluoroquinolones, clindamycin, and cephalosporins. They have maintained good activity against the vast majority of anaerobes. We do not retain these email addresses. At this time, most commercial laboratories use Etest methodology for performing anaerobic susceptibility testing on isolates sent to them for testing. Other antimicrobials, such as carbapenems, tigecycline, and combinations of a beta-lactam and a beta-lactamase inhibitor, possess a broader spectrum of activity against aerobic and anaerobic bacteria. Serum level measurements are often advocated for infants, young children, and occasionally adults, owing to their wide variations (115). Antibiotics sometimes work even when some of the bacterial species in a mixed infection are resistant to the antibiotic (eg, because of loss of support from other bacterial species or the necrotic anaerobic environment), especially if surgical debridement and drainage are adequate. Azithromycin is slightly less active than erythromycin against these species (117). Within this study we aim to give an extensive overview of the differences in antimicrobial susceptibility profiles between different European and surrounding countries. When testing was performed, blood isolates were always tested. Author information: (1)Department of Microbiology, LabPlus, Auckland District Health Board, Auckland, New Zealand. Each country tested different antibiotics, sometimes depending on the kind of infection and/or the anaerobic species isolated. High-level resistance can be caused by both mechanisms. Aceticlastic methanogen population abundance for Chlortetracycline (CTC) treatments ( Methanosaetaceae and Methanosarcinaceae sp .) 82). There is a dried anaerobic panel (AN02B; Sensititre [Trek Diagnostic Systems]) that includes 15 antimicrobials in a variety of dilution ranges, depending on the antibiotic (http://www.trekds.com/products/sensititre/c_pltformats.asp). He is active in the Anaerobe Society of the Americas, the IDSA, ASM, and the Surgical Infection Society. Studies using different proportions of the various B. fragilis group species may reflect different antibiograms for the B. fragilis group as a whole, when in reality, the only difference is the proportion of the various species used. The use of the quinolones is restricted in growing children because of their possible adverse effects on cartilage. Clinicians are less aware of all the taxonomic changes that have occurred and the names of new species. Chloramphenicol is widely distributed in body fluids and tissue, with a mean volume of distribution of 1.4 liters/kg of body weight (115). The overall clinical success rate for all anaerobes was 82.3%. A consistent observation is the high concentrations achieved in the CNS, even in the absence of inflammation. FluoroquinolonesThe earlier fluoroquinolones, such as ciprofloxacin and ofloxacin, are inactive against most anaerobic bacteria. Testing was performed by 85% (17/20) of laboratories for sterile body site isolates and by 70% (14/20) of laboratories for selected surgical wound isolates. Propionibacterium acnes isolates have also become more resistant to clindamycin, and this has been associated with prior therapy for acne (127). Goldstein et al. It has activity against both aerobic Gram-negative and Gram-positive bacteria, anaerobes, and certain drug-resistant pathogens (136). Other isolates have less predictable patterns, and certain anaerobes (some Clostridium, Fusobacterium, and Prevotella species, for example) may be penicillin-ampicillin resistant due to β-lactamase. Tetracycline resistance and the inducible transfer of resistance determinants can occur after exposure to low levels of these agents. The main difference between the two is the fact that aerobic bacteria require oxygen to remain alive, while anaerobic bacteria do not rely on oxygen for metabolic processes and survival. It has low MICs for the B. fragilis group. Other AgentsBacitracin was active in vitro against pigmented Prevotella and Porphyromonas spp. In our personal experience, clinicians are generally aware of the importance of anaerobic bacteria in a wide variety of infections. – Performance of susceptibility testing for anaerobic bacterial isolates recovered from selected cases can provide important information that can influence the choice of antimicrobial therapy. Anaerobic bacteria are naturally resistant to certain antibiotics, including the aminoglycosides and the earlier quinolones, and many anaerobes now exhibit resistance to several β-lactam agents as well. Levels exceeding 25 μg/ml are commonly considered potentially toxic in terms of reversible bone marrow suppression, and levels of 40 to 200 μg/ml have been associated with gray syndrome in neonates or encephalitis in adults (115). Failure to direct therapy against anaerobic organisms often leads to clinical failures. Anaerobes colonize the skin, oral cavity, and genitourinary and lower gastrointestinal tracts and generally do not cause infection. * The simple sugar is first converted to phosphoenolpyruvate before being broken down further to pyruvate. Reasons that may lead to failure of therapy include variation in the duration, severity, and extent of infection; lack of surgical drainage or poor source control; the patient's age, nutritional status, and comorbidities; impaired host defenses; poor penetration and low levels of the antimicrobial at the site of infection; enzymatic inactivation of antimicrobials; low pH at the infection site; and inaccuracies in the susceptibility testing procedure. This study shows a systematic approach to understanding how the different bacterial populations involved in the final conversion of organic matter into methane are inhibited by 15 antimicrobial agents with different specificities and modes of action. (100) The cephalosporinases are most often of the 2e class type and can be inhibited by three beta-lactamase inhibitors, clavulanic acid, sulbactam, and tazobactam. and AGNB (73 – anaerobic. 14). Clindamycin hydrochloride is rapidly and virtually completely absorbed from the gastrointestinal tract (121 (especially C. difficile) (93). Specialty Laboratories (operated by Quest Diagnostics) provides testing services for 6 antimicrobials (cefoxitin, penicillin, clindamycin, piperacillin-tazobactam, metronidazole, and imipenem) using Etest methodology (anaerobic susceptibility panel 5711). This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Anaerobic infections may be treated with antibiotics and other medications. The risk of fatal aplastic anemia with chloramphenicol is estimated to be approximately 1 per 25,000 to 40,000 patients treated. The authors of this study concluded that antimicrobial susceptibility testing may be indicated for patients whose blood specimens yield Bacteroides spp. The general principles are limited to questions of whether anaerobes are involved in this type of infection and if the agent chosen has activity against B. fragilis. – (Left) Dye representing the gradient application of antimicrobial stock solution, decreasing from the center of the plate. Aerobic bacteria need oxygen and anaerobic bacteria do not. a, FDA-approved indications for antimicrobials for the treatment of anaerobic infections, Percent resistance of Bacteroides fragilis group isolates and other anaerobes to antimicrobial agents The carbapenems (imipenem, meropenem, doripenem, and ertapenem) are very effective against all members of the B. fragilis group, and resistance is rare, at <0.1% (27, 112, 113). If made in-house, trays can be tailored to the particular needs of the laboratory, using the drugs and concentration ranges needed. Patient characteristics and clinical outcomes were analyzed. (117). are resistant to these agents by virtue of cephalosporinase production (79). The agar dilution method seemed reserved for “centers of excellence” or research centers. In some instances of polymicrobial infection, eradication of the aerobic component may be adequate, although it is well established that it is important to eliminate the anaerobic pathogens (2, 7 In 2007, The Committee on Antimicrobial Susceptibility Testing of the Japanese Society of Chemotherapy recommended the use of the CLSI method (32). The question of whether these tests are FDA approved for diagnostic purposes is a bit confusing. It may react negatively or even die if free oxygen is present. The most appropriate susceptibility test method will differ depending on whether the test is being done for a specific isolate in a hospital laboratory (or a commercial laboratory used by the hospital) or whether surveillance testing is being performed at a hospital or reference laboratory. At present, approximately 85% of B. fragilis isolates are susceptible to cefoxitin, but the other B. fragilis group species are more resistant (17). Resistance to β-lactam antibiotics.Anaerobes manifest three major mechanisms of resistance to β-lactam antibiotics: inactivating enzymes, mainly beta-lactamases (BLAs), which include penicillinases and cephalosporinases; low-affinity penicillin-binding proteins (PBPs); and decreased permeability through alterations in the porin channel (35). (Right) Plate after growth of strains. Multiplex PCR assay to detect common resistance determinants in B. fragilis. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint (SGE) system. Although several failures to eradicate anaerobic infections, including bacteremia, with chloramphenicol have been reported (114), this agent has been used for over 64 years for treatment of anaerobic infections. The enzyme has little or no hydrolytic activity for the second-generation antimicrobial cefoxitin (a cephamycin). A recent study (143) reported a pooled analysis of 4 randomized clinical trials (2000 to 2010) that assessed the comparative efficacy of moxifloxacin in complicated intra-abdominal infections of 745 microbiologically evaluable cases and focused on its efficacy against B. fragilis. Beta-lactamase production and susceptibilities to amoxicillin, amoxicillin-clavulanate, ticarcillin, ticarcillin-clavulanate, cefoxitin, imipenem, and metronidazole of 320 non-, Conjugal transfer of imipenem resistance in. It has also maintained good activity against the vast majority of anaerobes (17). It is likely that the levels of efflux pump genes transcribed and expressed are important. Ertapenem is a newer 1-beta-methyl carbapenem, stable to dehydropeptidase. Antimicrobial therapy for anaerobic infections usually should be given for prolonged periods because of their tendency to relapse. Detection of nim genes was described in 1996, using the universal primers NIM-3 and NIM-5 (51), followed by restriction analysis to identify the specific nim type (52). The choice will be based on published literature and surveys and local or specific patient data. Express enzymes that are generally aware of all anaerobic isolates fluoroquinolonesthe earlier fluoroquinolones such. 110 ) ( 54 ) speculated that other mechanisms 104 ) excellence ” or centers! Aerobes are able to determine all resistance determinants in B. fragilis group is composed of more than one of! 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