134. Characterization of circulating clinical multi-drug resistant and methicillin resistant Staphylococcus aureus isolates in Peru

Abstract

Abstract Background Multi-drug resistant and methicillin resistant Staphylococcus aureus (MDR-SA and MRSA, respectively) constitute a significant threat to hospitalized patients. Surveillance for antibiotic resistance is needed in settings where over-the-counter antibiotic use is widespread to identify increasing antibiotic resistance that limits treatment options of nosocomial infections. Methods We performed phenotypic and genotypic characterizations of MDR-SA prospectively obtained from hospitals in Lima, Peru between 2015 - 2018. We collected 3103 bacterial isolates from clinical specimens. Bacterial samples were identified by conventional microbiology and BD Phoenix, and antimicrobial susceptibility testing (AST) was performed by disc diffusion, E-test and BD Phoenix. Additionally, multiplex PCR detected mecA, femA, and lukS in MDR-SA isolates. We selected 80 S. aureus isolates that were resistant to ≥ 3 antimicrobial classes and/or resistant to oxacillin or cefoxitin for genomic characterization using an Illumina NextSeq 500 sequencer. Results Testing identified 232/3103 isolates as S. aureus, and 80/232 (34%) isolates were MDR-SA, resistant to up to nine different antimicrobial classes. We observed high proportions of resistance to aminopenicillins 80/80 (100%), macrolides 71/80 (89%), lincomycins 69/80 (86%), quinolones 66/80 (83%), aminoglycosides 38/46 (82%). Notably, 75/80 (94%) isolates were MRSA. Interestingly, AST revealed that 81% had inducible resistance to clindamycin. In contrast, all isolates were susceptible to vancomycin, linezolid, and daptomycin. Multiplex PCR revealed that 5% of isolates carried the lukS gene and the mecA gene. 76 % of the isolates carried a bifunctional aminoglycoside modifying enzyme and a aminoglycoside O-nucleotidyltransferase enzymes that confer resistance to aminoglycosides. We detected the ermA gene in 79% of the isolates. In silico multilocus sequence typing (MLST) assigned the sequence type 5 to 91.2% MRSA isolates with multiple high related clusters observed, indicating the possibility of nosocomial dissemination and possible outbreak events. Conclusion Antibiotic pressure on the resistance patterns of S. aureus is evident in the high levels of resistance seen in these clinical isolates. Disclosures All Authors: No reported disclosures.