Prevalence and antibiotic resistance profiles of Staphylococcus aureus colonizing HIV-infected adults in Botswana and risk factors for colonization

Rebecca Susann Bryson Fischer, The University of Texas School of Public Health


Staphylococcus aureus is normal human bacterial flora as well as an opportunistic pathogen. It can cause a range of disease, from minor skin infections to lethal invasive disease, like endocarditis, osteomyelitis, pneumonia, and sepsis. A major risk factor for staphylococcal infection is nasal colonization with S. aureus. Individuals with the human immunodeficiency virus (HIV) are at increased risk for both colonization and disease, and disease is often more severe. HIV disease parameters, such as CD4+ cell count and viral load, and use of anti-retroviral therapy (HAART) may influence risk of colonization and/or infection. Children have also recently established as a high-risk group for S. aureus infections, and both children and individuals with HIV often manifest with more severe disease. In Africa, S. aureus is emerging as a major pathogen, and isolates include highly virulent trains. Colonization and infection has been poorly described in the developing world. There is limited evidence to support that S. aureus infections among children and among persons with HIV in southern Africa are on the rise, though prevalence of infection and colonization in Botswana, where an estimated 25% to of the adult population has HIV and children are still infected with HIV at birth, has previously been undescribed. This study sought to identify key risk factors in the high-risk population of HIV-infected adults, but otherwise in general good health, in Botswana. A total of 404 HIV-infected outpatients of the Princess Marina Hospital and Bamalette Lutheran Hospital Infectious Disease Care Clinics participated, voluntarily, in this study. Patients were interviewed about their demographics, lifestyle, health history, and other potential risk factors, and S. aureus colonization was assessed by swabbing the anterior nares of each participant on two occasions, approximately 4 weeks apart. In the 404 adults enrolled in this study, S. aureus was detected at one or both study visits in 36.9% of participants, and 2.5% carried MRSA at some point. Colonized participants were grouped further by colonization state over the two study visits: 18.6% carried S. aureus intermittently (at least one visit), and 18.3% persistently carrier S. aureus. No study participant was persistently colonized with MRSA. Carriage rates in this study are comparable to those published in the literature, although carriage of MRSA was very low in this population, and persistent colonization of MRSA was not detected. Although this study did not include infection specimens, it provides the epidemiology of S. aureus circulating in the community and informs clinicians regarding antibiotic resistance of local strains. We also documented low antibiotic resistance circulating among HIV-infected adults in the region. Identification of key risk factors (demographic, health, and HIV-related clinical criteria) can aid clinicians in identifying individuals at high risk of S. aureus colonization and, thus, risk of infection or transmission. This research may inform targeted prevention strategies and treatment algorithms in this part of the world and lead to reduced morbidity and mortality due to S. aureus disease.

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Recommended Citation

Fischer, Rebecca Susann Bryson, "Prevalence and antibiotic resistance profiles of Staphylococcus aureus colonizing HIV-infected adults in Botswana and risk factors for colonization" (2014). Texas Medical Center Dissertations (via ProQuest). AAI3723362.