591. Mupirocin and Chlorhexidine Resistance in Staphylococcus aureus Isolated from Children in South Korea

BACKGROUND: Increasing prevalence of mupirocin-resistant Staphylococcus aureus have been reported, and chlorhexidine resistance has become an issue. This study aimed to investigate the prevalence of mupirocin and chlorhexidine resistance in both colonized and infection causing Staphylococcus aureus in children, and find factors associated with increased virulence. METHODS: Staphylococcus aureus, isolated from children <18 years old admitted at a single center, were collected prospectively from August 2017 to July 2018. The isolates underwent multilocus sequence typing and were screened for genes causing chlorhexidine resistance (qac A/B), quaternary ammonium resistance (smr), mupirocin resistance (ileS mutation, Mup A, MupB), and Pantone Valentine Leucocidin (pvl) toxin. RESULTS: During the study period, a total of 49 non-duplicate isolates were included, of which 69.4% (n = 34) were Methicillin-resistant Staphylococcus aureus (MRSA). Of the colonizers (n = 25), the most common sequence type was ST 72 (68.0%), whereas among pathogens (n = 24), ST 72 (29.2%) and ST 89 (29.2%) were most prevalent. Pathogens in this study caused abscess formation (n = 3), sepsis (n = 4), and skin infections such as cellulitis and omphalitis (n = 17). Mupirocin resistance was found in 16.0% among colonizers vs. 45.8% among pathogens (P = 0.023). High-level mupirocin resistance was more common (n = 3/25, 12.0%) than low-level mupirocin resistance (n = 1/25, 4.0%) in colonizers, whereas, pathogens had similar rates of low-level (25.0%) and high-level (n = 20.8%) mupirocin resistance. PVL toxin gene was more frequently found in colonizers than pathogens (64.0% vs. 33.3%, P = 0.032), and all isolates had quaternary ammonium resistance genes. Chlorhexidine resistance gene was found in only 3 MRSA isolates colonized in the nares of preterm infants. All were SCCmec type 4, however, two were ST 72, spa type t1054, which had high -level mupirocin resistance and PVL toxin gene. CONCLUSION: A PVL toxin gene-positive MRSA which had genes causing mupirocin and chlorhexidine resistance were found in the nasal carriages of preterm infants. These stains may cause failure of MRSA eradication in hospital settings, using conventional methods of nasal mupirocin application and chlorhexidine bathing. DISCLOSURES: All authors: No reported disclosures.