Bacterial isolates from Tracheal Aspirate of Patients in Intensive Care Unit and Their Antimicrobial Susceptibility Pattern in Tertiary Care Hospital in Dhaka, Bangladesh

Nosocomial infections are a critical issue among patients in the intensive care unit, particularly among intubated patients, leading to significant mortality and morbidity. So, accurate and timely identification and microorganism and their antimicrobial susceptibility pattern will help in the selection of proper antibiotics and prevent misuse in ventilated patients. The aim of this retrospective study was to determine the bacterial profile and susceptibility pattern of bacteria isolated from endotracheal aspirates of ventilator-associated pneumonia. This retrospective study was conducted in the department of microbiology and immunology, Bangladesh Medical University, Dhaka, from June 2023 to July 2024 for a period of one year. Written consent was taken from the authority. A total of 542 samples were collected from tracheal aspirates of the patients who were admitted to the hospital in the intensive care unit. A total of 542 tracheal aspirate samples were processed and cultured following standard techniques used in the medical microbiology laboratory. The isolated bacteria were identified by colony morphology, Gram staining, and biochemical reactions. Antibiotic susceptibility testing of the detected isolates was performed by Kirby-Bauer disc diffusion techniques as per guidelines set by the Clinical Laboratory Standards Institute (CLSI). Microsoft Excel software was used for data analysis. About 542 Tracheal aspirate samples were collected, of which 371(68.45%) showed bacterial growth. Out of 371 bacterial growths, the majority (44.28%) of culture-positive cases were in the age group 56- 65 years, and 67.15% were male. Of the 371culture growth, 371(100%) were gram-negative bacteria. Klebsiella spp. (45.83%) was the prevailing isolate, followed by Acinetobacter spp. (38.27%), Pseudomonas spp. (14.56%), Proteus spp. (0.81%), Enterobacter spp. (0.26%) and Morganella morganii (0.26%). Among Klebsiella spp. were resistance to ceftriaxone (95.29%), followed by cefotaxime (91.17%), ciprofloxacin (90.0%), same to cotrimoxazole (89.41%), amoxicillin, cefuroxime (91.17%), and Ceftazidime, tazobactam-piperacillin (88.23%). The highest sensitivity was exhibited for colistin, which demonstrated 1.77% resistance among Klebsiella spp., and the least resistant to amikacin (69.41%), meropenem (70.58%), and gentamicin (71.77%). Isolated Acinetobacter spp. were mostly resistant to cotrimoxazole and ciprofloxacin, ceftriaxone, ceftazidime, cefotaxime (95.07%), followed by gentamicin, amikacin (88.2%), meropenem, tazobactam-piperacillin (87.32%), but least resistance to colistin, which was 0.71%. Among Pseudomonas spp. showed the highest sensitivity, 98.14 % to colistin, followed by tazobactam-piperacillin (40.75%) and meropenem, and cefepime (35.18%), but higher resistant to ciprofloxacin (92.60%), followed by gentamicin (81.48%), ceftazidime (72.22%) and amikacin (70.37%). Most proteus spp. were resistant to amoxicillin, cotrimoxazole, ciprofloxacin, gentamicin and cefotaxime (100.0%). But higher sensitive to meropenem (66.66%), followed by ceftriaxone (33.33%). All the isolates were resistant to colistin, which is intrinsically resistant to it. Among Enterobacter spp. higher sensitive to colistin and cefepime, which was 100%. But other common drugs are resistant to it. In Morganella morganii, 100% sensitive to ceftazidime, amikacin, cefepime, tazobactam-piperacillin, netilmicin, but 100 % resistant to ciprofloxacin, gentamicin, meropenem, and colistin. These results indicate that the isolation rate from tracheal aspirate samples was high, and the increasing trend of antibiotic resistance to isolated bacteria is alarming, which may lead to treatment failure.