Date of Award

6-30-2011

Document Type

Dissertation

Degree Name

Master of Medicine (MMed)

Department

Pathology (East Africa)

Abstract

Objective: To establish the prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in healthcare workers (HCW) at Aga Khan University Hospital, Nairobi (AKUHN).

Background: Healthcare workers are a major reservoir of MRSA and may play a role in the spread of nosocomial MRSA infections. MRSA can cause significant morbidity and mortality. There is both molecular and epidemiological evidence linking HCW to MRSA outbreaks.

Method: A cross sectional study conducted between July and December 2010. Nasal swabs were taken from 246 randomly selected HCW from various departments.MRSA was identified using both phenotypic and genotypic methods. Antibiotic susceptibility testing of all Staphylococcus aureus isolates was done using the broth dilution MIC technique.

Results: The prevalence of nasal carriage of MRSA was 0% (95% CI:0.0%-1.5%) while that of methicillin sensitive Staphylococcus aureus (MSSA) was 18.3% (95% CI: 14.0%-23.6%). Carriage of MSSA was significantly higher in males (p=0.001, OR 5.74:2.09-15.77). Carriage was highest among HCW in the intensive care/high dependency units at 37%. Resistance to more than one class of antibiotics was seen in 37.7% of isolates. Prevalence of Panton Valentine Leukocidin (PVL) was 24.4%.

Conclusion: The absence of nasal carriage of MRSA by HCW working in AKUHN suggests that they are unlikely to be the source of infections caused by MRSA in patients attending AKUHN. Screening of HCW for nasal carriage of MRSA at AKUHN should be limited to an outbreak setting. The presence of the exotoxin PVL as well as the presence of multidrug resistant strains of Staphylococcus aureus shows that HCW can still be a potential source of infections caused by MSSA.

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