Genotypic and Phenotypic Detection of Fosfomycin and Tigecycline Resistance Genes From Clinical Isolates of Enterobacter cloacae.

Background The emergence of multidrug-resistant (MDR) Enterobacter species is a growing concern, driving increased morbidity and mortality, particularly due to hospital-acquired infections. Objective This study aimed to identify multidrug-resistant Enterobacter cloacae through the detection of antibiotic resistance genes. Methodology This cross-sectional study was conducted in the Department of Microbiology at Dhaka Medical College, Dhaka, Bangladesh, from November 2022 to June 2023 for a period of one year. All the clinically suspected patients who were presented with the infection of different body sites were divided into two groups: male and female. Then, each group is segmented into four specific age brackets: 20-30, 31-40, 41-50, and 51-60. The multidrug-resistant Enterobacter cloacae were isolated from patients admitted to Dhaka Medical College Hospital, Dhaka, Bangladesh. Samples, including urine, wound swabs, endotracheal aspirates, and blood, were collected from Dhaka Medical College's microbiology lab. Enterobacter species were identified through culture, Gram staining, and biochemical tests. Antibiotic susceptibility was tested using the disc diffusion method. PCR detected fosfomycin (fosA, fosA3, fosA4, fosB, fosC, fosX, fosL1) and tigecycline (tetX4, tetA) resistance genes. Results Among 390 samples, 251 (64.4%) isolates were culture-positive, of which 35 (13.9%) isolates were identified as Enterobacter species. Biochemical tests revealed 30 (85.7%) Enterobacter cloacae and five (14.3%) Enterobacter aerogenes. Among the isolated Enterobacter species, 19 (56.7%) isolates were MDR, five (16.7%) isolates were extensively drug-resistant (XDR), and three (10.0%) isolates were pan drug-resistant (PDR) Enterobacter cloacae isolates. Among 30 Enterobacter cloacae isolates, 29 (96.7%) were resistant to ceftriaxone, while 11 (36.7%) had the lowest resistance to tigecycline. Fosfomycin and imipenem resistance were observed in 22 (66.7%) and 21 (70.0%) of isolates, respectively. Among 20 fosfomycin-resistant Enterobacter cloacae, 13 (65.0%) carried fosA, four (20.0%) fosA3, and three (15.0%) fosA4. Among 11 tigecycline-resistant Enterobacter cloacae, tetA was detected in three (27.3%). Conclusion In conclusion, Enterobacter species often exhibit strong resistance to various antibiotics, performing antimicrobial susceptibility testing is essential before initiating treatment.