Evaluating the performance of different detection methods of Carbapenemase producing Gram-negative bacilli isolated from surgical site infections

Surgical site infections (SSIs) are still the most prevalent infections in health care facilities. The magnitude of the problem increased with the development of health care associated infections caused by Gram negative bacilli (GNB), which are resistant to Carbapenem antibiotics. This study aimed to assess the performance of various detection methods of carbapenemase-producing GNB; isolated from healthcare associated SSIs at different surgical units, Mansoura University Hospitals, Al- Dakahliya Governorate, Egypt. A total of 186 wound specimens were collected from patients showing symptoms and signs of SSIs; used for isolation of bacteria and then identification of these bacterial isolates according to colony morphology; microscopic examination and biochemical reactions. About 173 specimens were positive for bacterial pathogens; out of them 83 were GNB isolates. The most commonly isolated bacteria were; Klebsiella spp. 31 (37.3%), followed by Escherichia. coli 22 (26.5%), Pseudomonas. aeruginosa 17 (20.5%), Proteus spp. 10 (12.0%) and Enterobacter spp. 3 (3.6%). The antibacterial sensitivity testing of the total 178 bacterial isolates was assessed using the disc diffusion assay. Bacterial pathogens that were carbapenemase producers were tested using phenotypic, rapid colorimetric (Carba NP test) and genotypic methods. Among these isolated bacteria 31 (83.8%), 26 (70.3%) and 28 (75.7%) were carbapenem resistant; confirmed by MHT, Carba NP test and multiplex Polymerase chain reaction (PCR), respectively. Continuous screening of the bacterial antimicrobial susceptibility at local level and rational use of the antibacterial agents; is essential to decrease the emergence and spread of resistant bacterial pathogens.