Background: The rate of surgical site infection (SSI) in patients who undergo emergency operations is higher than in other patients. Previous studies showed an increasing role of gram- negative pathogens (GNP) in SSI. We aimed to identify GNP causing SSIs after emergency surgery, to characterize the carbapenemase-resistance genes in carbapenem-resistant pathogens (CRPs), and to identify the risk factors for SSI caused by CRP.
Method: We conducted a one-year prospective study from September 2014 in the Emergency Hospital of Cairo University Hospitals. Surveillance for SSIs was conducted according to the case definitions of the U.S. Centers for Disease Control and Prevention. Clinical specimens from patients suspected of having SSI were collected; pathogens were identified by Bruker matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectometry. Antimicrobial susceptibility was tested by the VITEK-2 and E-test. Carbapenem-resistant GNPs were characterized by multiplex polymerase chain reaction for IMP, VIM, SPM, OXA-48, NDM, KPC, BIC, AIM, GIM, SIM, and DIM. Clinical data for patients with SSI infected with CRP were compared with the non-infected patients for detection of risk factors.
Results: Surgical site infection affected 6.7% of patients who had emergency operations, and GNP represented 85% of these pathogens. Carbapenem-resistant pathogens caused 61% of the SSI, including all those caused by Acinetobacter baumannii, 70% of those caused by Pseudomonas aeruginosa, and 67% of those caused by Klebsiella pneumoniae. The PCR revealed that VIM, KPC, and NDM were the most common resistance genes. Risk factors for SSI were previous hospitalization, longer hospital stay, type of surgical incision, and abundant drainage; whereas previous hospitalization and infection by non-enteric environmental GNP were the risk factors for SSI caused by CRP.
Conclusion: The rate of SSIs caused by CRP was high after emergency surgery. VIM, KPC, and NDM were the most commonly found genes. Prior hospitalization and infection by non-enteric GNP were risk factors, which can be mitigated by eradication of bacterial populations in environmental reservoirs and control of transmission.
Keywords: VIM, KPC, NDM; pathogens; surgical site infection.