Asymptomatic Carriage of Sequence Type 398, spa Type t571 Methicillin-Susceptible Staphylococcus aureus in an Urban Jail: a Newly Emerging, Transmissible Pathogenic Strain

Abstract

Sequence type 398 (ST398) Staphylococcus aureus, frequently carried by livestock, has caused severe human infections and often carries transmissible antibiotic resistance genes. Among methicillin-susceptible S. aureus isolates colonizing Dallas County Jail detainees, 13.2% were ST398, spa type t571, and were genetically similar to human colonization isolates from New York, Chicago, and the Dominican Republic. Sequence type 398 (ST398) methicillin-resistant Staphylococcus aureus (MRSA) is often transmitted among livestock and animal handlers but is uncommonly associated with human disease in the United States (1). We unexpectedly identified ST398/t571 methicillin-sensitive S. aureus (MSSA) as the most common genetic background among MSSA isolates colonizing detainees in the Dallas County Jail. In this study, we compared the pulsed-field gel electrophoresis (PFGE) pulsotypes of isolates from the Dallas jail and from a single patient in Chicago with those of strains isolated in previous studies.Recognized first in Europe (2-9), ST398 MRSA has been isolated in the United States (10), Canada (11), and Latin America (12). ST398 methicillin-susceptible S. aureus (MSSA) isolates have been recovered from pigs (13), humans (14-17), and retail meat (18). Asymptomatic human colonization and infection with ST398 MSSA are rare in the United In January 2009, we screened the anterior nares and the hands of 928 detainees, housed in 68 divisions, called tanks, in the Dallas County Jail, for S. aureus carriage. Tanks had a capacity of 24 to 36 detainees. Detainees can interact with others within a single tank but have little interaction with those in other tanks. The study was approved by the Institutional Review Boards at the University of Chicago Medical Center and the University of Texas-Southwestern Medical Center. Recovered MSSA isolates were genotyped from subjects housed in a stratified random sample of 26 of the 68 tanks; all MRSA isolates were genotyped.In a separate study of S. aureus colonization among patients and household contacts (24), we also identified one patient in Chicago with ST398/t571 MSSA colonization.Multilocus sequence typing (MLST) (25), spa typing (26), PCR for the Panton-Valentine leukocidin (PVL) genes (27), and PFGE using Cfr9I digestion (22, 28) were performed. Antimicrobial susceptibilities were determined by automated testing (29).Among the 345 subjects in the 26 selected tanks, 110 (31.9%) carried MSSA. Of 158 MSSA isolates identified, 152 were available, and 34 MLST types were identified. Twenty isolates (13%) were ST398, the most common ST; all lacked PVL genes. Of the 345 subjects, the 16 (4.6%) who carried the 20 ST398 MSSA isolates were more likely than carriers of other MSSA genetic backgrounds to be female (P ϭ 0.0009) and older (P ϭ 0.01) ( Table 1).Among the 20 ST398 isolates, 18 were susceptible to ciprofloxacin, gentamicin, rifampin, and trimethoprim-sulfamethoxazole and resistant to clindamycin and erythromycin. The two other isolates differed in that one was susceptible to clindamyc...

Characterization of tetracycline and methicillin resistant Staphylococcus aureus strains in a Spanish hospital: Is livestock-contact a risk factor in infections caused by MRSA CC398?

“…It is remarkable that, a CC398 clade consisting in methicillin susceptible strains seems to be easily transmittable between humans. However, these strains present very different characteristics, MSSA-t571-CC398 being the more representative one (David et al, 2013;McCarthy et al, 2012;Price et al, 2012). In any case, in spite of that the human-to-human transferability of MRSA CC398 appears to be low, some hospital outbreaks of MRSA CC398 strains have also been detected (Verkade et al, 2012).…”

Prevalence and characterization of Staphylococcus aureus isolated from goat milk powder processing plants

“…Importantly, three non-typable S. aureus isolates by standard SmaI PFGE were confirmed as S. aureus ST398 by multilocus sequence typing (MLST). Since human infections caused by ST398 strains have been described (David et al, 2013;Mediavilla et al, 2012;Valentin-Domelier et al, 2011), this also proved the potential of the ST398 strain to invade humans.…”

Hand and Nasal Carriage of Discordant Staphylococcus aureus Isolates among Urban Jail Detainees

“…Thus, we did not find evidence of frequent transmission of MSSA among detainees, with the exception of ST398 (29). Table 4 shows the bivariate association of demographic characteristics with MRSA carriage.…”

“…September 2014 Volume 52 Number 9 jcm.asm.org 3423 2 and 4 tested detainees carried MSSA isolates that shared a concordant genotype (range, 12% [2/17] to 57% [4/7]); in 5 of the 11 tanks, only 2 detainees carried concordant MSSA, and in 4 of the tanks, ST398 MSSA/PVL-negative isolates were carried by Ͼ1 detainee, as described elsewhere (29). Thus, we did not find evidence of frequent transmission of MSSA among detainees, with the exception of ST398 (29).…”