Nasopharyngeal Staphylococcus aureus colonization among HIV-infected children in Addis Ababa, Ethiopia: antimicrobial susceptibility pattern and association with Streptococcus pneumoniae colonization

Abstract

Background. Staphylococcus aureus and Streptococcus pneumoniae are common inhabitants of the nasopharynx of children. HIV-infected children have higher risk of invasive diseases caused by these pathogens. With widespread use of pneumococcal conjugate vaccines and the emergence of methicillin-resistant S. aureus , the interaction between S. aureus and S. pneumoniae is of a particular significance. We sought to determine the magnitude of colonization by methicillin-sensitive and -resistant S. aureus and colonization by S. pneumoniae ; associated risk factors and antimicrobial susceptibility pattern among HIV-infected children in Addis Ababa, Ethiopia. Method. A prospective observational study was conducted among 183 HIV-infected children at ALERT hospital Addis Ababa, Ethiopia from September 2016 to August 2018. S. aureus and S. pneumoniae were identified using standard bacteriological techniques, antimicrobial susceptibility testing was performed on S. aureus and screening for methicillin resistance was carried out by amplifying the mecA gene. Risk factors were analysed by using binary logistic regression. Results. The prevalence of nasopharyngeal S. aureus , MRSA and S. pneumoniae colonization were 27.3, 2.7 and 43.2 %, respectively. Multivariable analysis indicated an inverse association between S. aureus and S. pneumoniae nasopharyngeal colonization [aOR, 0.49; CI, (0.24, 0.99); P=0.046]. The highest level of resistance in both methicillin-sensitive S. aureus (MSSA) and MRSA was observed against tetracycline. Conclusions. We found an inverse association between S. aureus and S. pneumoniae colonization among HIV-infected children. Continued assessment of the impact of pneumococcal conjugate vaccines and antiretroviral therapy on nasopharyngeal bacterial ecology is warranted.