Search

Bacteroides spp. are the most common anaerobic bacteria isolated from the human gastrointestinal tract. Several resistant genes are present in Bacteroides spp. However, most studies have focused on the prevalence of the c fi A gene in Bacteroides fragilis alone. We assessed the susceptibility to antimicrobial agents and the prevalence of cepA , cfiA , cfxA , ermF , nim , and tetQ genes in Bacteroides strains isolated from clinical specimens in our hospital. We isolated 86 B. fragilis and 58 non- fragilis Bacteroides strains from human clinical specimens collected from January 2011 to November 2021. Resistance against piperacillin (PIPC), cefotaxime (CTX), cefepime (CFPM), meropenem (MEPM), clindamycin, and minocycline was determined. The resistant rates of penicillins and cephalosporins in non- fragilis isolates were significantly higher than those in B. fragilis isolates. In B. fragilis isolates, the resistant rates of PIPC, CTX, and CFPM in cfxA- positive isolates were significantly higher than those in cfxA- negative isolates (71% vs. 16%, 77% vs. 19%, and 77% vs. 30%, respectively). Thirteen B. fragilis isolates harbored the cfiA gene, two of which were resistant to MEPM. Six of the 13 cfiA -positive B. fragilis isolates were heterogeneously resistant to MEPM. It is important to evaluate the use of MEPM as empirical therapy for Bacteroides spp. infections, considering the emergence of carbapenem resistance during treatment, existence of MEPM-resistant strains, and heterogeneous resistance. [ABSTRACT FROM AUTHOR]

Fecal pollution monitoring using fecal indicator bacteria has many limitations. Alternatively, using 16S rRNA gene Bacteroides-based polymerase chain reaction (PCR) showed promise because Bacteroides spp. are a major part of the gut microbiota. In the Philippines, duck backyard farming waste management is unmonitored. Hence, the objective of this study was to isolate Bacteroides DNA from duck feces and to establish genetic relatedness that can be used to develop new microbial source tracking markers. Fifty (50) duck fecal samples were collected. Of the 50, 20 were subjected to total DNA extraction and the remaining 30 were used for the isolation of Bacteroides. A total of 32 Bacteroides were isolated that included 6 B. nordii and 26 B. ovatus. A phylogenetic tree showing the host sources of Bacteroides generated five clusters. Four clusters came from this study, while the fifth cluster was composed of sequences from a study in Japan. This shows an intraspecies difference between Bacteroides species in the Philippines and Japan. This difference is a result of variations in the gut microbiome such as host species, diet, and geography. Results of this study will expand the present sequence database of Bacteroides from ducks that can be used in identifying sources of fecal pollution in the environment. [ABSTRACT FROM AUTHOR]

We investigated the epidemiology and antimicrobial susceptibility profiles of seven major Gram-negative bacilli (Escherichia coli , Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa , Acinetobacter spp., Stenotrophomonas maltophilia , and Bacteroides spp.) that caused bacteremia in Japan. We collected clinical information and isolates from patients aged 20 years or older who developed bacteremia during a year at three Japanese university hospitals and performed microbiological examination. In total, 628 cases were included, half of which were caused by E. coli (315 isolates). P. aeruginosa (56 isolates) was isolated most frequently among non-fermenting bacteria and 33 Bacteroides spp. were isolated. Mortality rates were the highest for P. aeruginosa (7-day, 16.1%; 30-day, 26.8%). The 7- and 30-day mortality rates ranged 3.8–9.0% and 8.3–17.6%, respectively, for Enterobacterales , and they were 15.2% each for Bacteroides spp. Regarding antimicrobial resistance, Enterobacterales and Acinetobacter spp. showed susceptibility to carbapenems and amikacin (98.0–100.0%). The susceptibility rates to ceftolozane/tazobactam ranged 82.4–99.0% for Enterobacterales and 92.9% for P. aeruginosa. More than 30.0% of E. coli isolates were resistant to fluoroquinolone. Extended-spectrum β-lactamase (ESBL) producers were found in 21.0% of E. coli and approximately 80% of those were resistant to fluoroquinolones. The susceptibility of the 33 Bacteroides spp. to carbapenems, ampicillin/sulbactam, and piperacillin/tazobactam was 100.0%. Among the ESBL producers, bla CTX-M group 9 was the major subgroup in E. coli (77.3%), and bla CTX-M group 1 was detected in 18.2% of E. coli and 50.0% of Klebsiella spp. Continuous surveillance is needed to understand the epidemiology and consider appropriate therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background The increasing prevalence of anaerobic bacteremia is a major concern worldwide and requires longitudinal monitoring. Methods We present one of the largest and longest longitudinal studies on the prevalence and antimicrobial resistance of Bacteroides , Clostridium , Fusobacterium , and Prevotella spp. isolated from blood culture samples using national comprehensive surveillance data in Japan during 2011–2020 as part of the Japan Nosocomial Infections Surveillance. Results Data for 41 949 Bacteroides spp. 40 603 Clostridium spp. 7013 Fusobacterium spp. and 5428 Prevotella spp. isolates were obtained. The incidences of bacteremia caused by Bacteroides fragilis , Clostridium perfringens , and Fusobacterium nucleatum significantly increased during the period (P <.0001). Among the 20 species analyzed, 18 showed no significant changes in susceptibility over time, including B. fragilis , C perfringens , and F. nucleatum. However, resistance to clindamycin increased in B. thetaiotaomicron (P =.0312), and resistance to ampicillin increased in B. ovatus (P =.0008). Conclusions Our comprehensive national surveillance data analysis demonstrated a continuous increase in the incidence of anaerobic bacteremia, particularly in B. fragilis , C. perfringens , and F. nucleatum. This may be linked to the increasing number of colorectal cancer cases or advancing methods for species identification and susceptibility testing, requiring cautious interpretation. The discovery of an upsurge in anaerobic bacteremia and potential alterations in susceptibility highlights the necessity for more extensive studies in this field. [ABSTRACT FROM AUTHOR]

Little information is available on the distribution of antimicrobial resistance genes in anaerobes in Japan. To understand the background of antimicrobial resistance in anaerobes involved in intra-abdominal infections, we investigated the distribution of eight antimicrobial resistance genes ( cepA, cfiA, cfxA, ermF, ermB, mefA, tetQ, and nim) and a mutation in the gyrA gene in a total of 152 organisms ( Bacteroides spp., Prevotella spp., Fusobacterium spp., Porphyromonas spp., Bilophila wadsworthia, Desulfovibrio desulfuricans, Veillonella spp., gram-positive cocci, and non-spore-forming gram-positive bacilli) isolated between 2003 and 2004 in Japan. The cepA gene was distributed primarily in Bacteroides fragilis. Gene cfxA was detected in about 9 % of the Bacteroides isolates and 75 % of the Prevotella spp. isolates and did not appear to contribute to cephamycin resistance. Two strains of B. fragilis contained the metallo-β-lactamase gene cfiA, but they did not produce the protein product. Gene tetQ was detected in about 81, 44, and 63 % of B. fragilis isolates, other Bacteroides spp., and Prevotella spp. isolates, respectively. The ermF gene was detected in 25, 13, 56, 64, and 16 % of Bacteroides spp., Prevotella spp., Fusobacterium spp., B. wadsworthia, and anaerobic cocci, respectively. Gene mefA was found in only 10 % of the B. fragilis strains and 3 % of the non- B. fragilis strains. Genes nim and ermB were not detected in any isolate. Substitution at position 82 (Ser to Phe) in gyrA was detected in B. fragilis isolates that were less susceptible or resistant to moxifloxacin. This study is the first report on the distribution of resistance genes in anaerobes isolated from intra-abdominal infections in Japan. We expect that the results might help in understanding the resistance mechanisms of specific anaerobes. [ABSTRACT FROM AUTHOR]

Obligate anaerobes exist as resident flora in various sites in humans, but they are also emphasized as endogenous causative microorganism of infections. We performed surveillance to understand the trend of drug susceptibility in obligate anaerobic bacteria in the Kinki area of Japan. In the experiment, we used 156 obligate anaerobe isolates collected from 13 institutions that participated in the Study of Bacterial Resistance Kinki Region of Japan. MALDI Biotyper was used to identify the collected strains, and among the 156 test strains, those that could be identified with an accuracy of Score Value 2.0 or more included 6 genera, 30 species, and 144 strains (Bacteroides spp. 77 strains, Parabacteroides sp. 2 strains, Prevotella spp. 29 strains, Fusobacterium spp. 14 strains, Porphyromonas spp. 2 strains, and Clostridioides difficile 20 strains), and they were assigned as subject strains for drug susceptibility testing. The drug susceptibility test was carried out by broth microdilution method using Kyokuto Opt Panel MP ANA (Kyokuto Pharmaceutical Industrial Co., Ltd., Tokyo, Japan) and judged according to CLSI criteria. As a result, Bacteroides and Parabacteroides species showed good sensitivities to tazobactam-piperacillin, imipenem, metronidazole and chloramphenicol, and low sensitivities to ampicillin, cefoperazone and vancomycin. Prevotella species showed good sensitivities to sulbactam-ampicillin, tazobactam-piperacillin, cefmetazole, imipenem, doripenem and metronidazole. Susceptibility rates to other drugs were slightly different depending on the bacterial species. Both Fusobacterium spp. and Porphyromonas spp. showed high sensitivities to many drugs. C. difficile was highly sensitive to vancomycin and metronidazole, having MIC 90 s of 0.5 μg/mL and ≤2 μg/mL, respectively. [ABSTRACT FROM AUTHOR]