Antimicrobial resistance of community and hospital acquired Staphylococcus aureus isolates to oxacillin and glycopeptides.
OBJECTIVE
To determine sensitivity pattern of Staphylococcus aureus isolates from the community and hospitals to methicillin, glycopeptides and other antimicrobial agents.


METHODS
Descriptive study.


METHODS
Private Pathology Laboratory in Lahore from January 2001 to April 2002.


METHODS
A total of 714 Staphylococcus aureus (S.aureus) isolates from the community and hospital were tested. Community acquired S.aureus strains (n=434) were isolated from specimens like pus from boils/pimples and nasal swabs of patients with asthma attending a local allergy clinic. The hospital acquired S.aureus (n=280) were isolated from specimens like pus from wounds/discharging sinuses, ear swabs, blood and urine. All the isolates were subjected to sensitivity test against Oxacillin, Vancomycin, Teicoplanin, Penicillin, Imipenem, Cefipime and other anti-staphylococcal agents by standard Kirby-Bauer disk diffusion method. Beta lactamase production by all the isolates was also determined by acidimetric test.


RESULTS
Significantly higher number of hospital acquired S.aureus isolates (p<0.01) were beta lactamase producing (96.07%) as compared to community acquired (81.79%). Methicillin (Oxacillin) resistance was also higher among hospital strains (31.1%) as compared to community ones (14.1%). No isolate from the community showed resistance to glycopeptides. While 0.3 percent and 0.7 percent of all S.aureus isolates were interpreted as resistant to Vancomycin and Teicoplanin respectively as there was no zone of inhibition. The resistance to these drugs was a bit higher among the MRSA (1.1% and 2.3% respectively). More than 90% of nosocomial MRSA strains were sensitive to Ofloxacin and Fucidic Acid. Resistance to Erythromycin, Lincomycin and Gentamicin was 70.1, 33.3 and 39.1% in that order. In general resistance to different antimicrobial was lower among S.aureus strains of community origin as compared to those of hospital origin.


CONCLUSIONS
Methicillin and multiple drug resistance is quite a significant problem in nosocomial as well as community acquired S.aureus strains. Moreover, it appears that resistance to glycopeptides has also emerged in our nosocomial S. aureus strains. Microbiology laboratories should make efforts not only to regularly screen S.aureus isolates for sensitivity to glycopeptides but also to determine MIC of the isolates.
Anwar
Muhammad Saeed
MS
Department of Patholgy, Postgraduate Medical Institute, Lahore. amir1985pk@hotmail.com
Bokhari
Shahid Raza
SR
D003428:Cross Infection / Q000188:drug therapy; D004352:Drug Resistance, Microbial; D006020:Glycopeptides / Q000494:pharmacology*; D006801:Humans; D010068:Oxacillin / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy; D013211:Staphylococcus aureus / Q000187:drug effects*
D006020:Glycopeptides; D010068:Oxacillin