Retrospective Bacterial Profile in Pus Sample and their Susceptibility Pattern in a Tertiary Care Hospital in Dhaka, Bangladesh

Pyogenic infections can be caused by various common microorganisms that require antibiotic therapy. The inappropriate use of antibiotics has resulted in the development of antibiotic resistance. This study aimed to identify bacterial isolates with pus infection and to determine their susceptibility pattern. This retrospective study was conducted in the Department of Microbiology and Immunology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh, between January 2023 and December 2023. 1320 pus samples were collected and all samples were cultured in blood agar and MacConkey agar media. The isolated bacteria were identified by colony morphology, gram staining, and biochemical reactions. Antibiotic susceptibility was tested using the Kirby Bauer disc diffusion method as per the National Committee for Clinical Laboratory Standards guidelines. Among culture-positive cases, the majority 232 (43.78%) were in the age group (21-40) years; male 360 (67.93%) were more commonly affected than female 170 (32.07%) patients. Out of 1320 samples, 530 (40.15%) yielded growth of organisms of which 397 (74.91%) were Gram-negative bacteria, and 133 (25.09%) were Gram-positive bacteria. Klebsiella spp. (31.70%) was the prevailing isolate followed by Staphylococcus aureus (25.09%), Pseudomonas spp. (20.70%), Acinetobacter spp. (10.95%), Proteus spp. (1.70%) and Enterobacter spp. (0.37%). Among gram-negative isolates, most Klebsiella spp. were resistant to amoxicillin (97.62%) followed by Cefuroxime (78.58%), cefotaxime (76.19%), cotrimoxazole (73.21%), and ciprofloxacin (71.42%). The highest sensitivity was exhibited for colistin, which demonstrated 10.72 % resistance among Klebsiella spp., and the least resistant to meropenem (26.79%), same resistance to amikacin and gentamycin (30.96%) and piperacillin-tazobactam (40.47%); respectively. Among gram-positive isolates, staphylococcus aureus was susceptible to linezolid (100%), vancomycin (100%), and cloxacillin (60.15%). They are highly resistant to amoxicillin (93.99%), Erythromycin (77.44%), ciprofloxacin (73.69%), cotrimoxazole (69.93%), and gentamicin (58.65%). These results indicate that the isolation rate from the pus sample was high and the increasing trend of antibiotic resistance in both gram-positive and gram-negative bacteria is alarming, which may lead to treatment failure.