Carriage rate and antimicrobial resistance profiles of Staphylococcus aureus among healthcare workers at a large tertiary referral hospital in Lusaka, Zambia

Background: Staphylococcus aureus is a frequent cause of hospital-acquired infections worldwide. The carriage of S. aureus among healthcare workers has been associated with transmission of the bacterium to susceptible patients. Objectives: The aim of this study was to determine the carriage rate, antimicrobial susceptibility profile and spa type of S. aureus among healthcare workers at a large tertiary referral hospital in Lusaka, Zambia. Methods: This was a prospectivecross-sectional study that involved the collection of nasal and hand swabs from 140 healthcare workers from May to July 2017 at the University Teaching Hospital in Lusaka. In this study, we recruited 103 nurses, 28 doctors and 9 laboratory scientists. Conventional microbiological methods were used to isolate and identify S. aureus. Antimicrobial susceptibility testing, including methicillin resistance was determined using the disc diffusion method, while molecular analysis of the isolates was achieved by spa typing. Results: The overall S. aureus carriage among the health care workers was 17.1% (24/140). Of these, 13.6% (19/140) and 8.6% (12/140) were nasal and hand carriers, respectively. Carriage rate was highest among doctors (17.9%, 5/28), followed by nurses (17.5%, 18/103) and laboratory scientists (11.1%, 1/9). About 25.8% (8/31) of the S. aureus isolates were methicillin-resistant and showed resistance to more than four antibiotics. About 25.8% (8/31) of the S. aureus isolates were positive for the spa gene. Of these, seven were typeable. Two spa types, t015 (42.8%, 3/7) and t069 (14.3%, 1/7) were detected, whereas the spa type for 42.8% (3/7) of the isolates were unknown. Conclusion: The carriage of S. aureus and prevalence of Methicillin-resistant S. aureus among healthcare workers examined was high. This calls for regular intervention measures such as screening and decolonizing of healthcare workers to reduce the carriage and spread of this pathogen in healthcare centres in Zambia. Keywords: Antimicrobial resistance, Carriage rate, Healthcare workers, Methicillin-resistant Staphylococcus aureus, Spa typing