Source and Antibiotic Susceptibility of Gram-negative Bacteria Causing Superficial Incisional Surgical Site Infections

Abstract Background Surgical site infections (SSIs) are a major public health problem worldwide and the second-most frequently reported type of nosocomial infection. The presence of Gram-negative bacteria (GNB) in the hospital environment is significantly associated with SSIs. As such, this study aimed to explore the rate, antibiotic profile and common sources of bacteria in SSI. Methods A cross-sectional study was conducted between August 2018 and July 2019 in three surgical centers in Kalar city, Kurdistan region, Iraq. A total of 512 patients, who underwent surgery were followed up with for superficial incisional SSI. Pre-, intra- and postoperative swabs were collected from patients and the surrounding hospital environment and processed for isolation and identification of GNB by microbiological and molecular methods. The isolates were typed by sequencing and tested for antibiotic resistance using the disc-diffusion technique. Results SSI developed in 113(22.07%) of the patients studied. GNB were involved in 48(9.38%) cases; among these, Klebsiella spp. were the predominant cause 21/48(43.75%), followed by Escherichia coli 14/48(29.17%), Pseudomonas aeruginosa 7/48(14.58%), Enterobacter spp. 3/48(6.25%) and A. baumannii 2/48(4.17%). Citrobacter koseri showed the lowest rate of infection 1/48(2.08%). Sequencing analysis and the antibacterial resistance profile revealed that 25(74.28%) of the 48 SSI isolates were from the hospital environment, whereas the rest were exogenous, with an undetermined source. The involved GNB were highly resistant to most antibiotics tested. Conclusion SSIs caused by GNB were mostly exogenous or from the hospital environment, not from endogenous sources. All of the bacterial isolates detected from SSI patients were multidrug resistant.