Isolation of Acinetobacter baumannii from patient and hospital environment: analyzing their antibiotic resistance, serum resistance & biofilm formation

Abstract

The Acinetobacter baumannii is a gram-negative coccobacillus also known as opportunistic bacterial pathogens currently creating great concern in clinical aspects due to their capacity to endure for extended periods of time in the environment and ability to cause multi-drug resistant infections. The objective of the study was to identify A. baumannii from hospital environments and admitted patients in hospital to analyze their antibiotic resistance, serum resistance and biofilm formation. Total 450 samples were collected from different wards of Rajshahi Medical College and Hospital. Among them we obtained 53 isolates of A. baumannii confirmed by polymerase chain reaction by targeting of the blaOXA-51 gene. From 53 isolates, 20 were from patient’s samples (7 endotracheal aspirates, 4 blood, 5 wound swab, 2 throat swab and 2 catheter tube ) and 33 isolates were from environment’s samples (bed sheet, surface of furniture, nebulizer machine, floor, nurse’s hand swab, food cart, medicine cart and trolleys). Subsequently, an antibiotic susceptibility test was done. Isolates from patient specimens were resistant to gentamicin (90%), amikacin (90%), cefepime, piperacillin-tazobactam (85%), ceftazidime(85%), and tetracycline (80%). A significant proportion of the isolates, 70%, displayed resistant against levofloxacin, imipenem, meropenem. Most importantly, 90% of all patient isolates were MDR. On the other hand, hospital environment’s isolates were resistant against ceftazidime(100%), imipenem(87.9%,), piperacillin-tazobactam (78.8%), and cefepime(78.8%). A significant proportion of the isolates, 69.7% and 66.7% were resistant against meropenem and gentamicin. Among them 80% of all isolates were MDR. The result of the serum bactericidal assay showed that almost 31% of isolates were serum resistant and 35% were sensitive and 34% were intermediate. Isolates from the environment's samples were 10% more resistant than the isolates from the patient's samples. Among environment’s isolates 36% isolates were resistant whereas among patient’s isolates only 26% were resistant. According to quantitative biofilm formation results, among 33 environmental isolates 17% of isolates formed strong biofilm, 14% formed moderate film, and 30% formed weak and 39% isolates did not form biofilm.