Haemophilus influenzae bacteraemia in adults at Chris Hani Baragwanath Academic hospital

Ismail, Hajira
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Haemophilus influenzae type b (Hib) was the major cause of meningitis in young children worldwide before the conjugate Hib vaccine became available in the late 1980s as part of national immunization programs. However, Hib vaccination does not confer protection against other serotypes of H. influenzae (Hi). The Hib vaccine was first introduced in The Gambia in 1997 and was introduced in South Africa as part of the National Expanded Program on Immunization (EPI) in 1999. Between 2000 and 2004 rates of Hib disease decreased significantly in <1 year old and <5 year old children, indicating the impact of the Hib vaccine introduced in 1999. Comparison of pre- and post-vaccination burden of disease data in adults is not yet available in Sub-Saharan Africa, including South Africa. In 2008, infants that were vaccinated from birth (i.e. in 1999) and who may have become infected with Hib are currently still considered as paediatric patients. This signifies that there is a large gap in data regarding the incidence as well as clinical and microbiological characteristics of Hi disease in adults. A literature survey has revealed that there are few studies that describe and highlight the profile of Hi infection in adults and no recent studies of adult bacteraemic disease in South Africa have been published. Therefore the aim of this study was to describe the clinical and microbiological characteristics of all adult cases with Hi bacteraemia at Chris Hani Baragwanath Academic Hospital (CHBAH) between January 2008 and December 2014. Study Design and Methods A single centre retrospective cohort study at CHBAH in Soweto was performed on patients ≥18 years of age who had a positive blood culture for Hi, from 2008-2014. Patients were identified from the ‘Group for Enteric, Respiratory and Meningeal Disease Surveillance’ in South Africa (GERMS-SA) database. Results and Discussion A total of 45 cases were identified. There were 6-9 cases annually until 2014 when there was only one. The median age was 40 years (IQR=20) and 23/45 (51%) were female. The foci of infection comprised pneumonia (33), bacteraemia without a focus (7), septic arthritis (3), meningitis (2), empyema (1), vasculitis (1) and cellulitis (1). A total of 35 (77%) cases had pre-disposing diseases of whom 33 (of 34 tested) were HIV-infected. Eleven (25%) had pre-existing diseases other than HIV that included chronic lung disease (4), diabetes mellitus (2), cancer (1), COPD (1), chronic kidney disease (1), diabetes with cancer (1), diabetes with chronic kidney disease and congestive cardiac failure (1). Twenty one cases had active TB. Sixteen (36%) patients died (12 early <2 days from admission). Seven isolates were resistant to ampicillin, but none to amoxycillinclavulanate. A total of 23/43 (53%) cases were non-typeable Hi, 10/43 (23%) Hib and 10/43 (23%) were of the non-Hib strains. No adults with Hib were identified after 2010. Conclusions H. influenza bacteraemia was an uncommon infection which disproportionately affected the HIV-infected and had a high mortality. There was a steady small number of 6-9 cases annually until a sudden marked decrease in 2014 with no Hib cases found in the last 4 years. It would be important to know if this decrease has been sustained. In addition, there was limited bacterial resistance and non-vaccine serotypes predominated.
A Research Report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Medicine in Internal Medicine, Johannesburg 2018