Clinical features, epidemiology, antimicrobial resistance, and exotoxin genes (including that of Panton-Valentine leukocidin) of gentamicin-susceptible methicillin-resistant Staphylococcus aureus (GS-MRSA) isolated at a paediatric teaching hospital in New South Wales, Australia.
OBJECTIVE
To describe the epidemiological, clinical, and laboratory features of gentamicin-susceptible methicillin-resistant Staphylococcus aureus (GS-MRSA) seen at a paediatric teaching hospital.


METHODS
Patients from whom GS-MRSA was isolated between 1 January 2001 and 31 December 2002 were enrolled. Retrospective chart review was performed. Susceptibility testing was performed with the Vitek2 system; PCR confirmed methicillin resistance. Phage typing and pulsed field gel electrophoresis (PFGE) was performed (utilising MLST/SCCmec-defined control strains). PCR detection of tst, luk-PV, and entA-entE was performed.


RESULTS
Eighty-five per cent of all Staphylococcus aureus isolates during the study period were methicillin-sensitive, and 15% were MRSA (9% GS-MRSA, 6% gentamicin resistant-MRSA). 100 GS-MRSA infections in 98 children were identified: 59 cases of skin/soft tissue, four bone and joint, four surgical site infections, three pneumonia, eight other types, and 22 represented colonisation. Ninety-nine isolates were non-multidrug resistant, but 17 strains were resistant to erythromycin, 7 to tetracyclines, 12 to ciprofloxacin, 11 to fusidic acid, 1 each to rifampicin and mupirocin. 44 isolates were Oceania strain (ST30-MRSA-IV), 20 were Queensland strain (ST93-MRSA-IV), ten were UK EMRSA-15 (ST22-MRSA-IV), eight were WA MRSA-1 (ST1-MRSA-IV), two were WA MRSA-5 (ST8-MRSA-IV), one was WA MRSA-2 (ST78slv-MRSA-IV), one was WA MRSA-15 (ST59-MRSA-IV), and the remainder were sporadics. Twenty patients were Pacific Islanders, of whom 12 had the Oceania strain; ten were Aboriginal, of whom eight had the Queensland strain. Sixty-eight isolates possessed luk-PV, including all Queensland strains and 91% of Oceania strains. Enterotoxin genes were detected in 25% of the isolates, and tst was detected in four isolates.


CONCLUSIONS
GS-MRSA is a significant paediatric problem in New South Wales: two minority groups are over-represented, multiple epidemic strains were detected, most community strains possess luk-PV, and many isolates are multidrug resistant.
The Children's Hospital at Westmead, Westmead, Australia. jgubbay@rogers.com
Jonathan B
JB
Gubbay
Iain B
IB
Gosbell
Thelma
T
Barbagiannakos
Alison M
AM
Vickery
Joanne L
JL
Mercer
Michael
M
Watson
D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004768:Enterotoxins / Q000235:genetics / Q000378:metabolism; D005098:Exotoxins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005839:Gentamicins / Q000627:therapeutic use*; D006776:Hospitals, Pediatric; D006784:Hospitals, Teaching; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007956:Leukocidins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D016106:Methicillin Resistance / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009517:New South Wales; D011446:Prospective Studies; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000208:ethnology / Q000473:pathology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018089:Superantigens / Q000235:genetics / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004768:Enterotoxins; D005098:Exotoxins; D005839:Gentamicins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal