Dataset Information

High Prevalence of USA300 Among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus on St. Kitts and Nevis, West Indies.

ABSTRACT: Limited information is available on antimicrobial susceptibility and clonal distribution of Staphylococcus aureus in the Caribbean region. The aims of this study were to determine the prevalence of antimicrobial resistance among S. aureus isolates and to reveal the frequency and population structure of methicillin-resistant S. aureus (MRSA) in St. Kitts and Nevis, a small island country in the West Indies. A total of 152 S. aureus isolates were collected from consecutive samples submitted to the clinical microbiology laboratory of the main referral hospital from March 2017 to January 2018. Samples came from all units in the hospital and a small number came from external submissions, and comprised a total of 119 clinical specimens and 33 nasal swabs collected from staff and patients. All S. aureus isolates were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Minimal Inhibitory Concentrations (MICs) of clinically relevant antimicrobials were determined by broth microdilution, and diversity of MRSA isolates was assessed by whole genome sequencing (WGS) analysis. MRSA accounted for 45% (69/152) of the isolates. The highest rates of resistance to non-?-lactam agents were observed for erythromycin (55%), moxifloxacin (41%), and levofloxacin (40%), whereas resistance to the other drugs tested was ?6%. All isolates were susceptible to ceftaroline, linezolid, teicoplanin, telavancin, and vancomycin. WGS-based multilocus sequence typing (MLST) showed that approximately 88% of the MRSA isolates belonged to ST8. Phylogenetic analysis on 801 single-nucleotide polymorphisms (SNPs) identified among the MRSA ST8 isolates indicates a large degree of genetic diversity. However, all ST8 strains clustered within the distinct clade that defines the USA300 North American Epidemic lineage (Panton-Valentine Leukocidin (PVL) +, arginine catabolic mobile element (ACME) +, Staphylococcal cassettes chromosome mec IVa (SCCmec IVa)). Our data show high levels of methicillin, macrolide, and fluoroquinolone resistance among S. aureus on St. Kitts and Nevis. The USA300 North American epidemic lineage is responsible for the vast majority of MRSA infections on this Caribbean island.

SUBMITTER: Guardabassi L

PROVIDER: S-EPMC6560147 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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High Prevalence of USA300 Among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus on St. Kitts and Nevis, West Indies.

Guardabassi Luca L Moodley Arshnee A Williams Andrea A Stegger Marc M Damborg Peter P Halliday-Simmonds Iona I Butaye Patrick P

Frontiers in microbiology 20190605

Limited information is available on antimicrobial susceptibility and clonal distribution of Staphylococcus aureus in the Caribbean region. The aims of this study were to determine the prevalence of antimicrobial resistance among S. aureus isolates and to reveal the frequency and population structure of methicillin-resistant S. aureus (MRSA) in St. Kitts and Nevis, a small island country in the West Indies. A total of 152 S. aureus isolates were collected from consecut ...[more]

PMID: 31231318

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Project description:USA300 methicillin-resistant Staphylococcus aureus (MRSA) isolates are usually resistant only to oxacillin, erythromycin, and, increasingly, levofloxacin. Of these, oxacillin and levofloxacin resistances are chromosomally encoded. Plasmid-mediated clindamycin, mupirocin, and/or tetracycline resistance has been observed among USA300 isolates, but these descriptions were limited to specific patient populations or isolated occurrences. We examined the antimicrobial susceptibilities of invasive MRSA isolates from a national surveillance population in order to identify USA300 isolates with unusual, possibly emerging, plasmid-mediated antimicrobial resistance. DNA from these isolates was assayed for the presence of resistance determinants and the presence of a pSK41-like conjugative plasmid. Of 823 USA300 isolates, 72 (9%) were tetracycline resistant; 69 of these were doxycycline susceptible and tetK positive, and 3 were doxycycline resistant and tetM positive. Fifty-one (6.2%) isolates were clindamycin resistant and ermC positive; 22 (2.7%) isolates were high-level mupirocin resistant (mupA positive); 5 (0.6%) isolates were trimethoprim-sulfamethoxazole (TMP-SMZ) resistant, of which 4 were dfrA positive; and 7 (0.9%) isolates were gentamicin resistant and aac6'-aph2'' positive. Isolates with pSK41-like plasmids (n = 24) were positive for mupA (n = 19), dfrA (n = 6), aac6'-aph2'' (n = 6), tetM (n = 2), and ermC (n = 8); 20 pSK41-positive isolates were positive for two or more resistance genes. Conjugative transfer of resistance was demonstrated between four gentamicin- and mupirocin-resistant and three gentamicin- and TMP-SMZ-resistant USA300 isolates; transconjugants harbored a single pSK41-like plasmid, which was PCR positive for aac6'-aph2'' and either mupA and/or dfrA. USA300 and USA100 isolates from the same state with identical resistance profiles contained pSK41-like plasmids with indistinguishable restriction and Southern blot profiles, suggesting horizontal plasmid transfer between USA100 and USA300 isolates.

Project description:Methicillin-resistant Staphylococcus aureus (MRSA) USA300 isolates have been recognized globally, not only in community but also in healthcare settings. USA300 isolates were initially resistant only to methicillin, but resistance to non-?-lactams has emerged with time. To evaluate the prevalence and antimicrobial susceptibility of USA300 isolates in Stockholm, we conducted a nine-year retrospective study. Of 5359 consecutive MRSA cases in Stockholm, isolates from 285 cases were USA300 strains according to the pulsed-field gel electrophoresis pattern. Of these cases, repeated isolates with altered antibiotic resistance patterns were observed in six individuals. Therefore, antimicrobial susceptibility testing was performed on totally 291 isolates. To study the phylogenetic relatedness of isolates in transmission events and genomic resistance traits, 35 isolates were further studied by whole genome sequencing (WGS). The incidence of MRSA was increased from 17.6 per 100,000 inhabitants in 2008 to 37.3 per 100,000 inhabitants in 2016, while the proportion of USA300 cases declined from 6.6% in 2008 to 2.6% in 2016. Among the USA300 isolates, 73.5% were community-associated, 21.3% healthcare-associated, and 5.2% had unknown acquisition. The highest resistance rate among non-?-lactams was found in erythromycin (86%), followed by fluoroquinolones (68-69%). 57% of the isolates were resistant to both erythromycin and fluoroquinolone. Simultaneous resistance to four non-?-lactam antibiotic classes was found in six isolates. Four isolates were susceptible to all non-?-lactam antibiotics. Ceftaroline, daptomycin, linezolid, mupirocin, rifampicin, teicoplanin, telavancin, trimethoprim-sulfamethoxazole and vancomycin retained full activity in the study. WGS analysis indicated that isolates from an outbreak were phylogenetically closely related. In conclusion, USA300 MRSA isolates in Stockholm have neither been limited to the community setting, nor remained susceptible to non-?-lactam agents. WGS is becoming a useful tool in tracing transmission events. The results herein provide the most up-to-date and comprehensive information regarding status of USA300 strains in this geographic area.

Dataset Information

High Prevalence of USA300 Among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus on St. Kitts and Nevis, West Indies.

Publications

High Prevalence of USA300 Among Clinical Isolates of Methicillin-Resistant <i>Staphylococcus aureus</i> on St. Kitts and Nevis, West Indies.

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