Bacterial Bloodstream Infections in HIV-Infected Adults Attending a Lagos Teaching Hospital
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J HEALTH POPUL NUTR 2010 Aug;28(4):318-326 ©INTERNATIONAL CENTRE FOR DIARRHOEAL ISSN 1606-0997 | $ 5.00+0.20 DISEASE RESEARCH, BANGLADESH Bacterial Bloodstream Infections in HIV-infected Adults Attending a Lagos Teaching Hospital Adeleye I. Adeyemi1, Akanmu A. Sulaiman2, Bamiro B. Solomon3, Obosi A. Chinedu1, and Inem A. Victor4 1Department of Microbiology, Faculty of Science, University of Lagos, Akoka, Nigeria, 2Department of Haematology and Blood Transfusion, Lagos University Teaching Hospital, Idi-Araba, Nigeria, 3Department of Obstetrics and Gynaecology, Bacteriology Research Laboratory, College of Medicine, University of Lagos, Lagos, Nigeria, and 4Institute of Child Health and Primary Care, Lagos University Teaching Hospital, Idi-Araba, Nigeria ABSTRACT An investigation was carried out during October 2005–September 2006 to determine the prevalence of bloodstream infections in patients attending the outpatient department of the HIV/AIDS clinic at the Lagos University Teaching Hospital in Nigeria. Two hundred and one patients—86 males and 115 females—aged 14-65 years were recruited for the study. Serological diagnosis was carried out on them to confirm their HIV status. Their CD4 counts were done using the micromagnetic bead method. Twenty mL of venous blood sample collected from each patient was inoculated into a pair of Oxoid Signal blood culture bottles for 2-14 days. Thereafter, 0.1 mL of the sample was plated in duplicates on MacConkey, blood and chocolate agar media and incubated at 37 °C for 18-24 hours. The CD4+ counts were generally low as 67% of 140 patients sampled had <200 cells/µL of blood. Twenty-six bacterial isolates were obtained from the blood samples and comprised 15 (58%) coagulase-negative staphylococci as follows: Staphylococcus epidermidis (7), S. cohnii cohnii (1), S. cohnii urealyticum (2), S. chromogenes (1), S. warneri (2), S. scuri (1), and S. xylosus (1). Others were 6 (23%) Gram-negative non-typhoid Salmonella spp., S. Typhimurium (4), S. Enteritidis (2); Pseudomonas fluorescens (1), Escherichia coli (1), Ochrobactrum anthropi (1), Moraxella sp. (1), and Chryseobacterium menin- gosepticum. Results of antimicrobial susceptibility tests showed that coagulase-negative staphylococci had good sensitivities to vancomycin and most other antibiotics screened but were resistant mainly to ampi- cilin and tetracycline. The Gram-negative organisms isolated also showed resistance to ampicillin, tetracy- cline, chloramphenicol, and septrin. This study demonstrates that co-agulase-negative staphylococci and non-typhoidal Salmonellae are the most common aetiological agents of bacteraemia among HIV-infected adults attending the Lagos University Teaching Hospital, Nigeria. The organisms were resistant to older- generation antibiotics often prescribed in this environment but were sensitive to vancomycin, cefotaxime, cefuroxime, and other new-generation antibiotics. Key words: Bacteraemia; Bacterial infections; HIV; HIV infections; Nigeria INTRODUCTION ies from state to state, with some recording as high as 10.6% (Benue state) and as low as 1.0% (Ekiti Nigeria has the highest population in Africa, with 1 state) (2). The clinical manifestation of HIV sec- in 6 Africans being a Nigerian. The rate of HIV/ ondary infections in developing countries, includ- AIDS prevalence has grown slowly from 1.9% in ing Nigeria, shows a high prevalence of infections 1993 to 5.4% in 2003, and by the end of 2004, it of the skin, gut, respiratory tract, tuberculosis, and was approaching 6% (1). However, a recent survey malnutrition (3,4). The virus has a specific capacity showed a decline to 4.6%, although the rate var- to infect the CD4+ class of T lymphocyte, resulting in progressive decline in their (CD4+) number (5). Correspondence and reprint requests should be This has serious health consequences since CD4+ addressed to: cells constitute about 10% of the total T cell-pool. Dr. Adeleye I. Adeyemi Department of Microbiology In AIDS patients, the number of CD4+ cells steadily Faculty of Science decreases, and by the time opportunistic infections University of Lagos set in, CD4+ cells may be almost absent. These Akoka infections include spirochetal, protozoan, viral, Nigeria fungal, mycobacterial and pyogenic bacterial infec- Email: [email protected] tions (6). The later includes gastrointestinal diseases Bacterial bloodstream infections in HIV-infected patients Adeyemi AI et al. caused by enteric bacterial pathogens characterized attending the outpatient department of the HIV by high rates of bacteraemia and frequent occur- clinic. rence of diarrhoea. The study was approved by the Medical Research Disseminated infections with Salmonella Typhi- and Ethics Committee of the Lagos University murium, S. Enteritidis, S. Arizona, S . Dublin, and Teaching Hospital. Some patients were already on other non-typhoidal Salmonella serotypes were reco- ART before the study commenced. gnized early in the HIV epidemic (7). Similarly, encapsulated bacteria, including Streptococcus pneu- Serological diagnosis of HIV moniae and Haemophilus influenzae are two of the Serum samples obtained from the 201 patients most common bacterial pathogens in HIV-infected were screened for HIV antibodies by enzyme-linked persons (8). Pseudomonas aeruginosa has emerged immunosorbent assay (ELISA) using Murex 1+2 as one of the most common causes of Gram-posi- kits (Murex Diagnostic, Dartfold, England). All sera tive bacteraemia and pneumonia in HIV-infected found positive by ELISA were confirmed by West- hospitalized patients, and its incidence in AIDS pa- ern blot (13). tients appears to be on the rise, with many studies demonstrating an annual increase in cases (9). Determination of CD4 Bacterial bloodstream infections constitute a sig- CD4 was estimated by micromagnetic bead meth- nificant public-health problem and present an im- od using kits supplied by Dynal Beads, UK. The portant cause of morbidity and mortality in HIV- procedure involved the addition of micromag- infected patients. A survey among HIV-I patients in netic bead coated with anti-CD14 antibodies to Malawi showed that 30% had bloodstream infec- whole blood. These magnetic beads bind to hu- tions. Organisms isolated were mainly S. pneumoni- man monocytes that express anti-CD14 antigens. ae (33%) and Mycobacterium tuberculosis (28%) (10). This is important so that these monocytes which In a retrospective three-year study of all episodes of equally express CD4 molecules are removed from bloodstream infections in HIV-infected patients in the whole blood before quantitation of CD4+ cells. Italy by Bonaldio et al. (11), the most frequent iso- Following the depletion of blood monocytes, the lates were coagulase-negative staphylococci (n=33), second micromagnetic bead coated with anti-CD4 S. aureus (n=7), Pseudomonas sp. (n=7), non-typhoid was added to the monocyte-depleted blood. The Salmonella (n=4), and fungi (n=1). Most patients blood was placed in the magnetic field so that all had a CD4 count of <100. the CD4 bearing cells in 100 µL of blood were at- tracted and isolated. These cells were resuspended To the best of our knowledge, there has been no in 100 µL of 5% glacial acetic acid tinted with Gen- previous study on bacterial bloodstream infections tian violet and counted under the light microscope of teeming HIV-infected patients that abound in using Neubauer counting chamber. this country, apart from the limited survey car- ried out by Ogunsola et al. (12). The present study Collection and processing of blood samples was conducted to determine the status of bacterial Venous blood samples (20 mL) were taken from each bloodstream infections in HIV-infected patients in patient, and 10 mL were aseptically inoculated into this environment in relation to their CD4 T lym- a pair of Oxoid Signal blood culture bottles system phocyte counts. This information will assist in asceptically. The blood samples were subsequently identifying clinical predictors of bloodstream infec- incubated for 2-14 days according to the standards tions and in planning appropriate therapy. of the World Health Organization (WHO) (14). MATERIALS AND METHODS Thereafter, 0.1 mL of the sample was drawn using a sterile syringe and plated out on MacConkey, blood Study subjects and chocolate agar plates using the streak plate technique. Duplicate plates were inoculated for Patients were consecutive attendants at the HIV each of the sample. The plates were then incubated clinic of the Lagos University Teaching Hospital at 37 0C for 18-24 hours and observed for bacterial (LUTH). The LUTH is a tertiary-level teaching hos- growth. The chocolate agar plates were incubated pital and referral centre located in Lagos attending under anaerobic conditions in an anaerobic jar for HIV-infected patients and others. The study was the possible isolation of microaerophiles. conducted during October 2005–September 2006. Characterization and identification of The cohort consists of HIV-infected individuals bacterial isolates referred to or identified at this hospital. The HIV- infected individuals included 86 males and 115 Colonies appearing on the agar plates were subcul- females aged 14-65 years. The entire subjects were tured for purity, and a minimum of three colonies Volume 28 | Number 4 | August 2010 319 Bacterial bloodstream infections in HIV-infected patients Adeyemi AI et al. with identical morphology was selected individu- Table 1. Age and sex distribution of 201 HIV/ ally and subjected to identification by standard AIDS patients studied biochemical tests (15). Finally, the isolates were Age- Male Female Total Total confirmed using the API 20E and API staph-kits group (n=86) (n=115) (n=201) % and were later identified using the API 20E (version (years) 4.0), API20 WE (version 6.0), and API STAPH (ver- 11-20 2 10 12 6.0 sion 4.0) software. Organisms identified as Staphy- lococcus were further subjected to coagulase test. 21-30 26 44 70 34.8 31-40 33 40 73 36.3 Testing of antimicrobial sensitivity 41-50 18 15 33 16.4 51-60 6 6 12 6.0 Antimicrobial sensitivity test was carried out on each isolate using Oxoid single antibiotics discs, fol- >60 1 - 1 0.5 lowing the recommended standards of the National count of <200 cells/µL of blood.