Community- versus healthcare-acquired bloodstream infections at Groote Schuur Hospital, Cape Town, South Africa

Abstract

Background. Bloodstream infections (BSIs) cause considerable morbidity and mortality. The epidemiology of bacterial infections differs in community and hospital settings. Regular surveillance and reporting of pathogens and antimicrobial susceptibility can assist in appropriate management of BSIs.

Objectives. To describe the distribution of organisms and of antibiotic susceptibility among isolates from blood cultures at a tertiary academic hospital during a 1-year period, stratifying by place of infection acquisition.

Methods. This was a retrospective descriptive study of bloodstream isolates from cultures from adults (>13 years of age) routinely submitted between 1 October 2011 and 30 September 2012 to the clinical laboratory at Groote Schuur Hospital, Cape Town, South Africa. Community-acquired infections were compared with healthcare-acquired infections, defined as infections developing at least 48 hours after admission or within 3 months of admission to a healthcare facility. Frequencies and proportions of infecting organisms are presented, along with susceptibility results for selected pathogens. The hospital-acquired isolates were stratified by ward (emergency, general medical or general surgical ward or intensive care unit (ICU)) to determine organism frequency and susceptibility patterns by hospital ward. Results. Among adults, 740 non-duplicate pathogens were isolated from BSIs. Nearly three-quarters of infections were healthcare acquired. Enterobacteriaceae and non-fermentative Gram-negative bacilli were predominant among healthcare-acquired pathogens (39.2% and 28.5%, respectively), while Enterobacteriaceae and Gram-positive organisms were the most common among community-acquired pathogens (39.2% and 54.3%, respectively). The majority of community-acquired Enterobacteriaceae were highly susceptible to antibiotics (gentamicin 95.6%, ceftriaxone 96.1% and ciprofloxacin 92.2%), whereas 64.6% of healthcare-associated isolates were susceptible to gentamicin, 58.5% to ceftriaxone and 70% to ciprofloxacin. All community-acquired Staphylococcus aureus isolates v. 52.4% of healthcare-acquired isolates were susceptible to cloxacillin. The susceptibility of healthcare-acquired Pseudomonas aeruginosa and Acinetobacter baumanii complex isolates was <80% to all antibiotics with the exception of colistin. Klebsiella spp., S. aureus and Escherichia coli were the commonest causes of healthcare- acquired infections in all areas outside of the ICUs, whereas Acinetobacter was common in the ICUs and rare in all other areas.

Conclusion. The distinction between community- and healthcare-acquired infections is critical in antibiotic selection because narrow- spectrum agents can be utilised for community-acquired infections. The considerable antibiotic resistance of healthcare-acquired pathogens highlights the importance of infection prevention and control. This type of surveillance could be incorporated into routine laboratory practice.