Whole genome characterization of methicillin resistant Staphylococcus aureus in an Egyptian Tertiary Care Hospital.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant healthcare-associated (HA-MRSA) pathogen due to its increased morbidity and mortality rates. There is a paucity of data regarding MRSA clones circulating in the Middle East in the literature, especially from Egypt. We aimed to identify the pattern of resistance and virulence in the propagating clones using NGS technologies for the whole genome sequence. METHODS: From an 18-month surveillance program for MRSA-positive patients, 18 MRSA isolates from surgical healthcare associated infections were selected. The Vitek2 system was used to assess antimicrobial susceptibility. The whole genome sequencing was performed using the NovaSeq6000. The reads were mapped to the reference genome (Staphylococcus_aureus_ATCC_BAA_1680), used for variant calling, screened for virulence/resistance genes, and typed using multi-locus sequence typing and spa typing. Correlation between demographic and clinical data and molecular findings were performed. RESULTS: All the MRSA isolates were highly resistant to tetracycline followed by gentamicin (61%) and highly susceptible to trimethoprim/sulfamethoxazole. Most of the isolates showed a high virulence profile. ST239 was the predominant sequence type (6/18), while t037 was the predominant spa type (7/18). Five isolates shared the same ST239 and spa t037. ST1535, an emerging MRSA strain, was the second most prevalent in our study. One isolate showed a unique pattern of a high abundance of resistance and virulence genes. CONCLUSION: WGS elucidated the resistance and virulence profiles of MRSA isolated from clinical samples of HAI patients with high-resolution tracking of clones predominant in our healthcare facility.

High Prevalence of VIM, KPC, and NDM Expression among Surgical Site Infection Pathogens in Patients Having Emergency Surgery.

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.