Typing of anaerobic bacteria isolated from clinical samples and determination of antibiotic resistance profiles

This study was conducted to identify anaerobic bacteria isolated from various clinical specimens obtained from patients with suspected anaerobic infection and to determine their antibiotic resistance profiles. The study was carried out in Adana Çukurova University Balcalı Hospital Medical Microbiology Laboratory between January 15, 2021 and November 1, 2021. Anaerobic culture was requested from a total of 863 samples. Routine anaerobic culture was performed on all of the samples requested in our laboratory. However, only 213 samples suitable for anaerobic culture were included in the study. Anaerobic bacteria were isolated in 22 (10.3%) of 213 samples included in the study: only anaerobic bacteria were isolated in 17 samples (7.98%), and both aerobic and anaerobic bacteria were isolated in 5 samples (2.3%). Only aerobic/ facultative anaerobic growth was observed in 74 specimens (34.7%), and no growth was observed in 119 specimens (55.86%). Isolated anaerobic gram-negative bacilli were identified using conventional methods and an automated diagnosis system (VITEK 2, bioMerieux, France). In the study, anaerobic bacteria were mostly isolated from abscess materials. 164 (77%) of the 213 cultured samples were abscesses and anaerobic bacteria were isolated in 11 (6.7%) of the abscess samples. Of the 22 samples with growth, 11 (50%) were abscess samples. A total of 22 anaerobic bacteria isolates were obtained from 12 male (54.5%) and 10 female (45.5%) patients. The number of anaerobic isolates obtained from patients under 18 years of age was 2/22 (9%), 17/22 (77.2%) between 18-60 years of age and 3/22 (13.6%) above 60 years of age. Of the anaerobic isolates, 6 (27.2%) Gr (-) anaerobic bacteria, 16 (72.7%) Gram (+) anaerobic bacteria (12 (54.54%) gram positive bacilli, 3 (18.18%) gram positive bacteria coke) has been observed. The most commonly isolated organisms were Cutibacterium spp. (22.7% n= 5%), followed by Actinomyces spp. (18.1% n=4), Prevotella spp. (13.6% n=3), Bacteroides spp. (9% n=2), Anaerococcus spp. ( 9% n=2), Clostridium spp. (9% n=2). The susceptibilities of ampicillin, clindamycin, cefoxitin, metronidazole, moxifloxacin, meropenem, piperacillin-tazobactam and amoxicillin-clavulanic acid were determined for each isolate by antibiotic concentration gradient method (E test, bioMerieux, France). The most active antimicrobial agents were moxifloxacin (95.5%), piperacillin-tazobactam (95.5%) and amoxicillin-clavulanic acid (95.5%). Less active were cefoxitin (90.9%), meropenem (90.9%),clindamycin (77.3%), ampicillin (59.1%), and metronidazole (22.7%), respectively. The ampicillin susceptibility rate of anaerobic isolates that underwent ADT was 59.1%. The percentage of total susceptibility to Gram positive bacilli and cocci was 81.25% (Gram positive bacilli 91.7%, Gram positive cocci 50%), and Gram negative anaerobic bacteria were all resistant (100%). A sensitivity to meropenem antibiotic was 90.9%. It was observed that 87.5% of Gram positive bacteria (Gram positive bacilli 91.7%, Gram positive cocci 75%) and 100% of Gram negative bacteria were susceptible. Sensitivity to metronidazole antibiotic was 22.7%. Resistance was mainly observed in Gram-positive anaerobic bacteria (100%), showing good activity against most Gram-negative bacilli (83.3%). Sensitivity to clindamycin was observed at a rate of 77.3%. This ratio varies between Gram positive and Gram negative isolates, and 81.3% of Gram positive bacteria (Gram positive bacilli 75%, Gram positive cocci 100%) and 50% of Gram negative bacilli are susceptible. Sensitivity to Cefoxitin was observed at a rate of 90.9%. 87.5% of Gram-positive bacteria (Gram-positive bacilli 91.7%, Gram-positive cocci 100%), 66.7% of Gram-negative bacteria were susceptible and 33.3% were moderately susceptible.