Anaerobic bacteria colonizing the lower airways in lung cancer patients

Anaerobes comprise most of the endogenous oropharyngeal microflora, and can cause infections of airways in lung cancer patients who are at high risk for respiratory tract infections. The aim of this study was to determine the frequency and species diversity of anaerobes in specimens from the lower airways of lung cancer patients. Sensitivity of the isolates to conventional antimicrobial agents used in anaerobe therapy was assessed. Respiratory secretions obtained by bronchoscopy from 30 lung cancer patients were cultured onto Wilkins-Chalgren agar in anaerobic conditions at 37°C for 72-96 hours. The isolates were identified using microtest Api 20A. The minimal inhibitory concentrations for penicillin G, amoxicillin/clavulanate, piperacillin/tazobactam, cefoxitin, imipenem, clindamycin, and metronidazole were determined by E-test. A total of 47 isolates of anaerobic bacteria were detected in 22 (73.3%) specimens. More than one species of anaerobe was found in 16 (53.3%) samples. The most frequently isolated were Actinomyces spp. and Peptostreptococcus spp., followed by Eubacterium lentum, Veillonella parvula, Prevotella spp., Bacteroides spp., Lactobacillus jensenii. Among antibiotics used in the study amoxicillin/clavulanate and imipenem were the most active in vitro (0% and 2% resistant strains, respectively). The highest resistance rate was found for penicillin G and metronidazole (36% and 38% resistant strains, respectively). The results obtained confirm the need to conduct analyses of anaerobic microflora colonizing the lower respiratory tract in patients with lung cancer to monitor potential etiologic factors of airways infections, as well as to propose efficient, empirical therapy.     

Susceptibility to antimicrobial drugs of enterotoxin producing strains of Bacteroides fragilis isolated from different countries

Twenty two Bacteroides fragilis strains isolated from clinical samples in different countries (England, France, the Netherlands, Poland and USA) were used in the experiments. In all strains the presence of enterotoxin (fragilysin) gene was found by PCR with primers 404/407. Drug susceptibility of B. fragilis strains was determined with Etest (MICs for penicillin G, ceftriaxone, amoxicillin/clavulanic acid, imipenem, clindamycin and metronidazole). MICs were estimated in accordance to the NCCLS recommendations (1997). All tested strains were susceptible to imipenem and metronidazole. Twenty one strains were susceptible and one was intermediate susceptible to amoxicillin/clavulanic acid. Fourteen strains were resistant to ceftriaxone and five were found highly resistant to clindamycin. All examined strains were resistant to penicillin G. Four tested strains were simultaneously resistant to penicillin G, ceftriaxone and clindamycin (three French human strains isolated from postoperative wound, peritoneal fluid and bone inflammation, and one strain isolated from a pig).     

Comparison of E test and agar dilution methods for determining antibiotic susceptibilities of anaerobic bacteria and viridans streptococci isolated from blood

The antimicrobial susceptibilities of 311 strains of anaerobic bacteria and 140 strains of aerobic bacteria, isolated from blood after dental extraction, were determined by the E test and compared with the results obtained by the agar dilution method on PDM-ASM 2 agar. E test MICs agreed within +/-1 dilution step to the agar dilution MICs in 93%, 52%, 90%, 94% of the tested anaerobes for penicillin V, cefaclor, clindamycin and erythromycin, respectively. For aerobic bacteria the agreement was > or = 90% for the antibiotics tested. The in vitro activities of penicillin V, clindamycin and erythromycin were higher than the activity of cefaclor against the majority of bacteria tested.     

Antibiotic resistance among anaerobic Gram-negative bacilli: lessons from a French multicentric survey

Temporal changes of antibiotic susceptibilities among anaerobes in France are followed in our laboratory since 1992. For Bacteroides strains, resistance increased from 1992 to 1998 for amoxicillin-clavulanic acid, cefotetan and clindamycin. The present study evaluates the situation in 2000 for 434 Gram-negative anaerobic clinical isolates (obtained from 9 large university hospitals) by testing amoxicillin and ticarcillin alone or combined with clavulanic acid, cefoxitin, cefotetan, imipenem, clindamycin and metronidazole (using the NCCLS-approved method for MIC determination. The main genera tested included Bacteroides (359 strains of the fragilis group), Prevotella (40 strains), Fusobacterium (23 strains) and miscellaneous species (8 strains). Resistance rates within the B. fragilis group were: amoxicillin-clavulanic acid 5.6%, ticarcillin 33%, ticarcillin-clavulanic acid 2%, cefoxitin 13%, cefotetan 44%, clindamycin 33%, imipenem 1% and metronidazole <1%, respectively. Only one strain of B. fragilis was resistant to metronidazole (MIC=64 mg/L); due to the presence of the nimA gene on the chromosome. Resistance to imipenem or metronidazole was only found among the B. fragilis species. These two former drugs excepted, B. fragilis was less resistant to antibiotics than the other species. beta-lactamase production was detected for 357/359 strains of the fragilis group, 26/40 stains of Prevotella and 3/23 strains of Fusobacterium. Dynamic changes of antibacterial resistance are occurring within the B. fragilis group: decreased resistance to amoxicillin-clavulanic acid, ticarcillin-clavulanic acid, imipenem while resistance for cefoxitin, cefotetan, clindamycin continues to increase. Regular antibiotic surveys are needed as a source of information to guide the empirical therapy of anaerobic infections.     

Update on resistance of Bacteroides fragilis group and related species with special attention to carbapenems 2006-2009

The susceptibility trends for the species of the Bacteroides fragilis group against various antibiotics were determined using data from 4 years [2006-2009] on 1957 isolates referred by 8 medical centers participating in a National Survey for the Susceptibility of B. fragilis. The antibiotic test panel included doripenem, ertapenem, imipenem, meropenem, ampicillin:sulbactam, piperacillin:tazobactam, cefoxitin, clindamycin, moxifloxacin, tigecycline, chloramphenicol and metronidazole. MICs were determined using agar dilution methods following CLSI recommendations. Genetic analysis of isolates from 2008 with elevated MICs (>2 μg/mL) to one or more of the carbapenems to detect presence of the cfiA gene was performed using PCR methodology. The results showed an increase in the resistance rates to the β-lactam antibiotics. High resistance rates were seen for clindamycin and moxifloxacin (as high as 60% for clindamycin and >80% for moxifloxacin), with relatively stable low resistance (5.4%) for tigecycline. For carbapenems, resistance in B. fragilis was 1.1%-2.5% in 2008-9. One isolate resistant to metronidazole (MIC 32 μg/mL) was observed as well as isolates with elevated MICs to chloramphenicol (16 μg/mL). Genetic analysis indicated that the cfiA gene was present in some but not all of the isolates with high MICs to the carbapenems. These data indicate that there continue to be changes in susceptibility over time, and that resistance can be seen among the carbapenems. High antibiotic resistance rates tend to be associated with specific species.     

Surveillance and trends of antimicrobial resistance among clinical isolates of anaerobes in Kuwait hospitals from 2002 to 2007

The susceptibility trends for all anaerobes processed by the Anaerobe Reference Laboratory against various antibiotics were determined by using data for 2557 isolates referred by all government hospitals in Kuwait from 2002 to 2007. MIC were determined for the following anti-anaerobic antibiotics: amoxicillin–clavulanic acid, clindamycin, imipenem, meropenem, metronidazole, penicillin, piperacillin, piperacillin–tazobactam and vancomycin (for Gram-positive anaerobes only), using E-test method. The commonest isolates were Bacteroides fragilis (36.8%), followed by Peptostreptococcus spp. (21.9%), Bacteroides ovatus (15.5%) and Prevotella bivia (12.1%). In addition, Prevotella oralis and other Bacteroides spp. represented 8.5% and 8.1% of total number of isolates, respectively. Resistance rate varied among the antimicrobial agents and the species tested. The β-lactams, with the exception of penicillin, were the most active drugs. Piperacillin–tazobactam was the only antimicrobial agent to which all the isolates were uniformly susceptible. Imipenem and metronidazole were highly active with resistance rate of only <5% recorded against most isolates. However, 42.8, 55.8 and 9.3% of Clostridium difficile isolates were resistant to imipenem, clindamycin and meropenem, respectively. It is noteworthy that from 2002 to 2007, there was a gradual increase in resistance rates to clindamycin, amoxicillin–clavulanic acid and piperacillin among B. fragilis. Periodic surveillance of antibiotic resistance among the anaerobic bacteria is recommended as a guide to empiric antibiotic use and formulation of guideline for appropriate choice of antimicrobial therapy in anaerobic infections.     

Antimicrobial Susceptibility of Clostridium difficile from Different Sources

A total of 79 Clostridium difficile strains from healthy young and elderly adults, elderly patients without gastrointestinal disease, elderly patients receiving antibiotics without gastrointestinal complications, and elderly patients with antibiotic-associated diarrhea or pseudomembranous colitis were tested for their susceptibilities to 24 antimicrobial agents. All of the 79 strains were inhibited by low concentrations of rifampicin, metronidazole, fusidic acid, vancomycin, ampicillin, and penicillin G. The strains were highly resistant to aminoglycosides, trimethoprim, sulfamethoxazole, nalidixic acid, and cycloserine and often resistant to neomycin, cefoxitin, and cefalexin. Wide variations in the susceptibility of C. difficile strains to erythromycin, clindamycin, lincomycin, chloramphenicol, and tetracycline were found. Strains resistant to erythromycin, clindamycin, and lincomycin were more frequently found among strains isolated from elderly adults than those isolated from young adults, with particularly high frequency among strains isolated from elderly patients receiving antibiotics. None of the 23 strains isolated from healthy young adults was resistant to chloramphenicol. All of the 14 strains resistant to erythromycin, clindamycin, lincomycin, and chloramphenicol were sensitive to tetracycline and all of the 15 strains resistant to erythromycin, clindamycin, lincomycin, and tetracycline were sensitive to chloramphenicol. Only one out of 19 tetracycline-resistant strains was highly toxigenic, whereas 42 (70%) of 60 sensitive strains were highly toxigenic.     

E-test antibiotics susceptibility of strict anaerobic bacteria

The E-test is convenient for testing susceptibility of anaerobes. From September 1998 to September 1999, 194 strains (105 Gram-positive bacteria, 89 Gram-negative bacteria) of clinically relevant samples were tested against five antibiotics benzylpenicillin, amoxicillin-clavulanic acid, clindamycin, metronidazole and imipenem on blood agar plates. Resistance to benzyl penicillin is widespread and Gram-negative bacteria and resistance to amoxicillin-clavulanic acid is exceptional. Metronidazole is very effective against anaerobes except non-spore-forming aerotolerant Gram-positive rods and Peptostreptococcus micros.     

Antibiotic susceptibility of Bacteroides fragilis group strains in Hungary

Resistance rates to different antibiotics of 495 Bacteroides fragilis group strains were followed between 1987 and 1994 in Hungary. In 1992 the strains were collected in three different laboratories, whereas during the other periods strains were isolated in one centre. Metronidazole, chloramphenicol, imipenem and amoxicillin/clavulanic acid were the most active drugs. A high level of resistance was observed in 1987 for ampicillin (88% at > 4 mg/L), erythromycin (51% at > 4 mg/L), tetracyclin (53% at > 8 mg/L) and clindamycin (27% at > 4 mg/L). The same level of resistance was seen during the further years for clindamycin and ampicillin. Resistance to cefoxitin increased from 6% to 11% between 1987 and 1993/1994. No differences in resistance rates were observed between the strains collected in the three centers. For 100 strains, the results of the E test were compared with those of the micro-broth dilution test, both being used routinely for testing the antibiotic susceptibility of Bacteroides fragilis group strains in this period.     

Susceptibility trends of Bacteroides fragilis group and characterisation of carbapenemase-producing strains by automated REP-PCR and MALDI TOF

Susceptibility testing of clinical isolates of anaerobic bacteria is not considered, often, mandatory in routine clinical practice and the treatments are empirically established. Thus, periodic monitoring of the susceptibility patterns of anaerobic bacteria is advisable. The aim of this study was to update on resistance of Bacteroides fragilis group in our Institution with special attention to carbapenems reporting metallo-beta-lactamase producing strains for the first time in Spain, and to compare fingerprinting analysis results obtained by using automated rep-PCR (DiversiLab System) and MALDI-TOF MS. A total of 830 non-duplicated clinical isolates of the B. fragilis group recovered from the years 2006 to 2010 were studied. B. fragilis was the most prevalent species (59.5%). The total susceptibility of B. fragilis group isolates were: penicillin, 13.3%; amoxicillin/clavulanic, 89.6%; piperacillin-tazobactam, 91.8%; cefoxitin, 65.8%; ertapenem, 95.9%; imipenem, 98.2%; clindamycin, 53.4% and metronidazole, 96.4%. The percentage of sensitive isolates did not change significantly over time for amoxicillin/clavulanic, cefoxitin, clindamycin and metronidazole. A slight increase in the rate of resistance to ertapenem and imipenem was observed. Imipenem resistance and carbapenemase production were detected for the first time in our laboratory in the year 2007. No other report of carbapenemase-producing B. fragilis in our country has been previously published. Six imipenem-resistant isolates were MBL-producing and PCR positive for cfiA gene. Four of them were PCR positive for IS-like immediately upstream cfiA gene and two of them were negative. Both, automated rep-PCR (DiversiLab) and MALDI-TOF MS, revealed a great genetic diversity among carbapenem-producing strains suggesting the acquisition of novel resistance genes more than clonal dissemination of them. Both methods seem to be useful tools for fast and accurate identification and strain typing of B. fragilis group in the daily laboratory routine. Because of the relevant increase observed in Bacteroides species isolated from blood cultures and the appearance of carbapenemase-producing strains in our Institution, we recommend to test the antimicrobial susceptibility of the isolates, at least in the most severe patients.     

Antibiotic Susceptibility of Bacteroides fragilis Group Strains in Hungary

Resistance rates to different antibiotics of 495 Bacteroides fragilis group strains were followed between 1987 and 1994 in Hungary. In 1992 the strains were collected in three different laboratories, whereas during the other periods strains were isolated in one centre. Metronidazole, chloramphenicol, imipenem and amoxicillin/clavulanic acid were the most active drugs. A high level of resistance was observed in 1987 for ampicillin (88% at > 4 mg/L), erythromycin (51% at > 4 mg/L), tetracyclin (53% at > 8 mg/L) and clindamycin (27% at > 4 mg/L). The same level of resistance was seen during the further years for clindamycin and ampicillin. Resistance to cefoxitin increased from 6% to 11% between 1987 and 1993/1994. No differences in resistance rates were observed between the strains collected in the three centers. For 100 strains, the results of the E test were compared with those of the micro-broth dilution test, both being used routinely for testing the antibiotic susceptibility of Bacteroides fragilis group strains in this period.     

产ESBLs肺炎克雷伯菌AmpC酶的检测及耐药性分析

目的了解深圳市人民医院产ESBLs肺炎克雷伯菌中产AmpC酶的情况及其耐药性。方法收集产ESBLs肺炎克雷伯菌临床株126株,应用Tris-EDTA纸片法检测AmpC酶。用琼脂稀释法测定菌株对11种抗生素的最低抑菌浓度（MIC）。结果126株ESBLs阳性的肺炎克雷伯菌中12株检出AmpC酶,检出率为9.5%。AmpC阳性菌株对头孢西丁、头孢他啶、氨曲南、氨苄西林/舒巴坦和阿莫西林/克拉维酸的耐药率达100%,对阿米卡星和哌拉西林/他唑巴坦的耐药率分别为83.3%和33.3%,其中头孢西丁、头孢他啶、氨曲南、阿莫西林/克拉维酸、阿米卡星和哌拉西林/他唑巴坦的耐药率显著高于AmpC阴性株（P〈0.05）。结论深圳市人民医院产ESBLs肺炎克雷伯菌中检出AmpC酶阳性株,其耐药性强于单产ESBLs菌株。     

Antimicrobial Susceptibility Testing of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Determined by Microdilution Method Using a New Medium

Antibiotic susceptibility testing of Helicobacter pylori isolates was performed by broth microdilution method with MegaCell^TM RPMI-1640 Medium (SIGMA). Fifty five clinical isolates of H. pylori were tested against metronidazole, tinidazole, amoxicillin, and clarithromycin. The results were compared to those obtained by standard agar dilution method. The microdilution method performed with new medium, showed excellent correlation with agar dilution results, with 100% agreement for metronidazole, 96.3% for amoxicillin, 90.7% for clarithromycin, and 92.8% for tinidazole. MICs determined by proposed method were highly reproducible: replicate results were variable within one-two-fold dilution by using different inocula and different batches of medium.     

Antibiotic Susceptibility of Helicobacter pylori Clinical Isolates: Comparative Evaluation of Disk-Diffusion and E-Test Methods

Antimicrobial susceptibility of 25 Helicobacter pylori strains isolated from patients with acid peptic diseases were tested for in vitro sensitivity to commonly used antibiotics using disk-diffusion and E-test, methods. All strains tested were susceptible to tetracycline by E-test, with the minimum inhibitory concentration (MIC) values being <0.125 μg/ml for all strains except for 6 (<0.023 μg/ml). However 1 strain was resistant by disk-diffusion method. One strain was resistant to clarithromycin both by disk diffusion and E-test (MIC <48 μg/ml), and 1 strain was resistant only by disk diffusion. Only one strain was resistant to amoxicillin by disk diffusion and E-test (MIC >256 μg/ml). For ciprofloxacin, three strains were resistant by disk diffusion and two by E-test (MIC <32 μg/ml). Sixteen strains were resistant to metronidazole by disk diffusion and E-test (MIC ≥ 8 μg/ml), and 1 was resistant only by E-test (MIC <48 μg/ml). Overall, 64% of the strains were resistant to metronidazole. The MIC for metronidazole was also tested by agar-dilution method, and metronidazole resistant strains had an, MIC >8 μg/ml. The disk-diffusion method showed excellent correlation with E-test results; there was 100% agreement for amoxicillin a other antibiotics showed 90% to 95% accuracy. Disk diffusion is cheaper than E-test (approximately 2.6 cents vs. US$2.60), is easy to perform, and is a reliable method for testing H. pylori susceptibility to antimicrobial agents in the clinical microbiology laboratory.     

Anaerobic microbiology in 198 cases of pleural empyema: a Bulgarian study

The aim of the study was to evaluate the incidence of anaerobic bacteria in 198 patients with pleural empyema and the susceptibility of isolates to eight antibacterial agents. Isolates were identified by the Crystal anaerobes identification system, API System rapid ID 32 A and/or routine methods. Susceptibility was tested by Sceptor MIC system for anaerobic bacteria and limited agar dilution method. Anaerobic bacteria were found in 74.2% of the patients and included 247 strains within 21 genera. The predominant anaerobes were Gram-positive anaerobic cocci (52 isolates), Fusobacterium (51), microaerophilic streptococci (24), Prevotella (19) and Bacteroides species (11). Common species/groups were Fusobacterium nucleatum (in 27.2% of specimens yielding anaerobes), Micromonas micros (8.2%), Finegoldia magna (7.5%), Bacteroides fragilis group (6.8%), Peptostreptococcus anaerobius (6.1%) and F. necrophorum (5.4%). No resistance to chloramphenicol and ampicillin/sulbactam was detected. The susceptibility rates of Gram-negative anaerobic isolates to penicillin, cefoxitin, clindamycin, clarithromycin, metronidazole and tetracycline were 63.8%, 90.2%, 87.8%, 58.6%, 98.8% and 71%, and those of Gram-positive anaerobes were 79.2%, 100%, 84.3%, 68.4%, 41.9% and 75%, respectively. The wide diversity of isolated anaerobic genera and species and the susceptibility patterns of the isolates emphasize the role of the anaerobic microbiology in cases of pleural empyema.     

Antimicrobial susceptibility of anaerobic bacteria in Bulgaria

ObjectivesThe antimicrobial susceptibility of anaerobic bacteria isolated from clinical specimens in the referent for Bulgaria anaerobic laboratory was studied in a period of 25 years/1983–2007/.MethodsNCCLS – recommended agar dilution methods were used. β-lactamase activity was determined with nitrocefin discs.ResultsThe 29 antimicrobial agents included in the study were divided according to their in vitro activity against the anaerobic isolates into 4 main groups for guiding empirical treatment: 1st group of metronidazole, chloramphenicol, meropenem, imipenem and combinations of β-lactam antibiotics with sulbactam – with high activity and drugs of choice for treatment; 2nd group – clindamycin, cefoxitin, carbenicillin/and azlocillin, piperacillin/ – with a good activity and low percent of resistant strains; 3rd group – of tetracycline and erythromycin with higher percent of resistant strains including the new macrolides as josamycin, clarithromycin, roxithromycin and azithromycin; 4th group – penicillins/ampicillin, amoxicillin, penicillin/and cephalosporins/cefamandole, cefazolin, cefotaxime and cefoperazone/ – not suitable for treatment of infections including Bacteroides fragilis group strains, with a very high percent of resistant strains, probably due to β-lactamase activity in most of the strains.ConclusionA continued updating and a follow-up in the changes of antibiotic susceptibility are necessary in every country as resistance patterns vary not only between geographical regions but also even among medical centers and hospitals which may be connected with differences in antibiotic usage in man and animals.     

Antimicrobial susceptibility, β-lactamase and enterotoxin production in <Emphasis Type="Italic">Bacillus cereus</Emphasis> isolates from clinical and food samples

The antimicrobial susceptibility of 30 clinical and 30 food Bacillus cereus isolates was determined. All isolates were susceptible to streptomycin, ciprofloxacin and gentamicin, 90 % of them to clindamycin and vancomycin, and 67 % to erythromycin. All isolates were resistant to amoxicillin with clavulanic acid, ampicillin, cefotaxime, ciprofloxacin, cloxacillin, cefotaxime with clavulanic acid and penicillin. The MIC values (determined by E-tests) were 48–256 mg/L for ampicillin, 0.19–1.5 mg/L for gentamicin, 0.125–1.0 mg/L for clindamycin, 0.047–4.0 mg/L for erythromycin and 1.5–16 mg/L for vancomycin. The MICs 4.6–18.75 g/L were observed for penicillin using the microdilution method. The presence of metallo-β-lactamases was detected by E-test for 100 % of strains. Nonhemolytic diarrheal enterotoxin (NHE) was produced by 98.3 % of strains, while 31.7 % of them produced hemolytic diarrheal enterotoxin (HBL). Clinical isolates produced 10 % more HBL than food isolates. The psychrotrophic strains isolated from food samples produced NHE at 6.5 °C in 73 % of cases.     

Comparison of amoxicillin and ampicillin in single-dose oral treatment of males with gonococcal urethritis

Amoxicillin in single oral doses of 2.0 g, 2.0 g plus 1.0 g probenecid, or 3.0 g was compared with ampicillin 3.5 g plus 1.0 g probenecid in the treatment of 203 males with uncomplicated acute gonococcal urethritis. Cure rates above 95% were produced by all treatments except the 2.0-g amoxicillin dose, which cured 89% of patients. Of 198 pretreatment gonococcus isolates tested by an agar dilution technique for susceptibility to penicillin G, ampicillin and amoxicillin, over 50% showed relative resistance (MIC > 0.06 μg/ml) to the antibiotics. However, amoxicillin was somewhat more active against isolates showing considerable resistance (MIC ≥ 1.0 μg/ml) to penicillin G or ampicillin. Adverse effects of amoxicillin were few: two patients reported transient nausea and six noted short-lived diarrhea. No hypersensitivity reactions were observed.     

Antimicrobial susceptibility of lactic acid bacteria isolated from a cheese environment

In the production of the Spanish traditional blue-veined Cabrales cheese, lactic acid bacteria strains free of antibiotic resistance that have a transferrable capacity are necessary as components of a specific starter. To select for these bacteria, the minimum inhibitory concentration (MIC) of 12 antibiotics and 2 mixtures (containing beta-lactamase inhibitor and penicillin) were determined by microbroth and agar dilution techniques in 146 strains belonging to the genera Lactococcus, Enterococcus, Lactobacillus, and Leuconostoc. The antibiotic-resistance profiles of Lactococcus and Enterococcus species were different from those of Lactobacillus and Leuconostoc, but clear genus- or species-associated patterns were not observed. Cefoxitin and metronidazole were not effective against bacteria of these genera. The MICs of beta-lactam antibiotics for lactobacilli and leuconostoc isolates were higher than those for lactococci and enterococci, but no strain was clinically resistant. All lactobacilli and leuconostoc isolates were resistant to high levels of vancomycin, a type of resistance not seen among the tested members of the genera Lactococcus and Enterococcus. The majority of the observed resistance appeared to be either intrinsic or nonspecific, although some strains of Lactococcus lactis, Enterococcus spp., and Lactobacillus spp. were resistant to antibiotics, such as chloramphenicol, erythromycin, clindamycin, or tetracycline.     

In vitro activity of 11 antibiotics against 74 anaerobes isolated from pediatric intra-abdominal infections

The in vitro activity of 11 antimicrobials was tested against 74 recent anaerobic isolates obtained from pretreatment cultures in pediatric patients with complicated intra-abdominal infections using the CLSI M11-A-6 agar dilution method. Carbapenems, beta-lactamase inhibitor combinations and metronidazole retained good activity, while all Bacteroides fragilis group species produced beta-lactamase and were penicillin resistant and 43% were either intermediately susceptible or resistant to clindamycin. Cefoxitin had moderate activity against B. fragilis but poor activity against Bacteroides thetaiotaomicron and other B. fragilis group isolates.