Adane Mihret

Nasal carriage rate of methicillin resistant Staphylococcus aureus among Dessie Referral Hospital Health Care Workers; Dessie, Northeast Ethiopia

BackgroundStaphylococcus aureus is a common cause of community and hospital acquired infections. One of the important sources of staphylococci for nosocomial infection is nasal carriage among hospital personnel. Emergence of drug resistant strains especially methicillin resistant Staphylococcus aureus is a serious problem in hospital environments. The aim of this study was to determine the nasal carriage rate of methicillin resistant Staphylococcus aureus among Dessie Referral Hospital healthcare-workers in Ethiopia.MethodsA cross sectional study was conducted on a total of 118 healthcare workers. Nasal swabs were collected and cultured on Mannitol Salt Agar. Slide coagulase test was performed. An oxacillin susceptibility test was carried out on Muller Hinton agar using modified Kirby-Bauer disc diffusion method.ResultsOf the 118 healthcare workers, 34 (28.8%) carried S. aureus of which 15 were methicillin resistant. Therefore, 12.7% of all HCWs were identified as MRSA carriers. The rate of methicillin resistance among all S. aureus isolates was 44.1% (15/34). MRSA carriage was particularly high among nurses (21.2%). The highest rate of MRSA carriers (57.1%) were workers of surgical wards.ConclusionsThe high rate of nasal MRSA carriage among healthcare workers found in this study indicates the need for adjusted infection control measures to prevent MRSA transmission in our healthcare setting.

Analysis of Host Responses to Mycobacterium tuberculosis Antigens in a Multi-Site Study of Subjects with Different TB and HIV Infection States in Sub-Saharan Africa

Background Tuberculosis (TB) remains a global health threat with 9 million new cases and 1.4 million deaths per year. In order to develop a protective vaccine, we need to define the antigens expressed by Mycobacterium tuberculosis (Mtb), which are relevant to protective immunity in high-endemic areas. Methods We analysed responses to 23 Mtb antigens in a total of 1247 subjects with different HIV and TB status across 5 geographically diverse sites in Africa (South Africa, The Gambia, Ethiopia, Malawi and Uganda). We used a 7-day whole blood assay followed by IFN-γ ELISA on the supernatants. Antigens included PPD, ESAT-6 and Ag85B (dominant antigens) together with novel resuscitation-promoting factors (rpf), reactivation proteins, latency (Mtb DosR regulon-encoded) antigens, starvation-induced antigens and secreted antigens. Results There was variation between sites in responses to the antigens, presumably due to underlying genetic and environmental differences. When results from all sites were combined, HIV- subjects with active TB showed significantly lower responses compared to both TST- and TST+ contacts to latency antigens (Rv0569, Rv1733, Rv1735, Rv1737) and the rpf Rv0867; whilst responses to ESAT-6/CFP-10 fusion protein (EC), PPD, Rv2029, TB10.3, and TB10.4 were significantly higher in TST+ contacts (LTBI) compared to TB and TST- contacts fewer differences were seen in subjects with HIV co-infection, with responses to the mitogen PHA significantly lower in subjects with active TB compared to those with LTBI and no difference with any antigen. Conclusions Our multi-site study design for testing novel Mtb antigens revealed promising antigens for future vaccine development. The IFN-γ ELISA is a cheap and useful tool for screening potential antigenicity in subjects with different ethnic backgrounds and across a spectrum of TB and HIV infection states. Analysis of cytokines other than IFN-γ is currently on-going to determine correlates of protection, which may be useful for vaccine efficacy trials.

Diagnosis of latent tuberculosis infection in healthy young adults in a country with high tuberculosis burden and BCG vaccination at birth

BackgroundOne third of the world’s population is thought to have latent tuberculosis infection (LTBI) with the potential for subsequent reactivation of disease. To better characterize this important population, studies comparing Tuberculin Skin Test (TST) and the new interferon-γ release assays including QuantiFERON®-TB Gold In-Tube (QFT-GIT) have been conducted in different parts of the world, but most of these have been in countries with a low incidence of tuberculosis (TB). The aim of this study was therefore to evaluate the use of QFT-GIT assay as compared with TST in the diagnosis of LTBI in Ethiopia, a country with a high burden of TB and routine BCG vaccination at birth.MethodsHealthy medical and paramedical male students at the Faculty of Medicine, Addis Ababa University, Ethiopia were enrolled into the study from December 2008 to February 2009. The TST and QFTG-IT assay were performed using standard methods.ResultsThe mean age of the study participants was 20.9 years. From a total of 107 study participants, 46.7% (95%CI: 37.0% to 56.6%) had a positive TST result (TST≥10 mm), 43.9% (95%CI: 34.3% to 53.9%) had a positive QFT-GIT assay result and 44.9% (95%CI: 35.2% to 54.8%) had BCG scar. There was strong agreement between TST (TST ≥10mm) and QFT-GIT assay (Kappa = 0.83, p value = 0.000).ConclusionThe TST and QFT-GIT assay show similar efficacy for the diagnosis of LTBI in healthy young adults residing in Ethiopia, a country with high TB incidence.

Multi-center evaluation of a user-friendly lateral flow assay to determine IP-10 and CCL4 levels in blood of TB and non-TB cases in Africa.

OBJECTIVE Multi-center evaluation of a user-friendly lateral flow test for detection of IP-10 and CCL4 levels in Mycobacterium tuberculosis (Mtb) antigen-stimulated whole blood samples from tuberculosis (TB) suspects. DESIGN AND METHODS A quantitative lateral flow (LF)-based assay platform was applied to detect chemokines IP-10 and CCL4. Chemokine quantitation was achieved using interference-free, fluorescent up-converting phosphor (UCP) labels. The new assays allowed worldwide shipping and storage without requiring a cold chain and were tested at seven institutes (including Ethiopia, Malawi, The Gambia, South Africa, Uganda and Namibia) employing portable lightweight readers for detection of the UCP label. At each site, clinical samples, confirmed TB and non-TB (i.e. other respiratory diseases (ORD)) cases, were collected and analyzed simultaneously with quality control (QC) human IP-10 or CCL4 standards. RESULTS Performance of the UCP-LF assay in Africa using QC standards indicated high robustness allowing quantitative detection between 100 and 100,000pg/mL. The optimized assays allowed successful determination of chemokine levels using 1μL whole blood sample from the locally recruited subjects with TB or ORD. CONCLUSION This African multi-center trial further demonstrated the applicability of the low-tech and robust UCP-LF platform as a convenient quantitative assay for chemokine detection in whole blood. Ambient shipping and storage of all assay reagents and the availability of lightweight standalone readers were acknowledged as essential requirement for test implementation in particular in remote and resource-limited settings.

Dendritic Cells Activate and Mature after Infection with Mycobacterium tuberculosis

BackgroundDendritic cells (DCs) can take up an array of different antigens, including microorganisms which they can process and present more effectively than any other antigen presenting cell. However, whether the interaction between the human DC and Mycobacterium tuberculosis represents a defense mechanism by the invaded host, or helping the invader to evade the defense mechanism of the host is still not clearly understood.FindingsTo analyze the interactions between M. tuberculosis and immune cells, human peripheral blood monocyte-derived immature DCs were infected with M. tuberculosis H37Rv wild type strain and flow cytometry was used to analyse cell surface expression markers. The ability of the M. tuberculosis infected DC to induce T cell proliferation using 5 and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution technique was also investigated. DCs were found to internalize the mycobacteria and show dose dependent infection and necrosis with different multiplicity of infection. Flow cytometry analysis of cell surface expression markers CD40, CD54, CD80, CD83, CD86 and HLA DR in infected DC revealed significant (p < 0.05) up regulation following infection with M. tuberculosis in comparison to immature DC with no stimulation. Lipopolysaccharide (LPS) from Salmonella abortus equi, a known DC maturation agent, was used as a positive control and showed a comparable up regulation of cell surface markers as observed with M. tuberculosis infected DC. It was revealed that the M. tuberculosis infected DC induced T cell proliferation.ConclusionThese data clearly demonstrate that M. tuberculosis induces activation and maturation of human monocyte-derived immature DC as well as induces T cell proliferation in vitro.

Hepatitis B virus infection among medical waste handlers in Addis Ababa, Ethiopia

BackgroundHealthcare wastes contain a wide range of microorganisms among which hepatitis B virus (HBV) are the most significant pathogens. No data about the prevalence of HBV among medical waste handlers is available in Addis Ababa, Ethiopia. Therefore; this study was conducted to describe the prevalence of HBV infection among medical waste handlers in Government hospitals of Addis Ababa, Ethiopia.FindingsA cross sectional study was conducted among 252 medical and non-medical waste handlers working in three Government hospitals of Addis Ababa between May to July, 2010. Predesigned and tested questionnaire was used to collect soiociodemographic information. Blood sample was taken from 252 waste handlers and serum was tested for Hepatitis B surface antigen (HBsAg) and anti-Hepatitis core antigen (anti-HBcAg) using Enzyme Linked Immuno Sorbent Assay.Of the 126 Medical Waste Handlers and 126 Non Medical Waste Handler, HBsAg was detected in 8 (6.3%) and 1 (0.8%), and anti-HBcAg in 60 (47.6%) and 40 (31.7%), respectively. Significant differences were observed in the detection rates of HBsAg (OR: 8, 95% CI: 1.02, 63.02; p = 0.01), Anti-HB c Ag (OR: 1.5, 95% CI: 1.1, 2.1; p = 0.01) and either markers (OR: 1.7, 95% CI: 1.2, 2.2; p = 0.001) in medical waste handlers compared to non medical waste handlers. 19.8% were trained to handle medical waste and none was immunized against HBV.ConclusionThis study shows a high prevalence of HBV infection in medical waste handlers compared to non medical waste handlers. Lack of training on how to handle medical waste among medical waste handlers was high.

Impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients

BackgroundThe immunologic environment during HIV/M. tuberculosis co-infection is characterized by cytokine and chemokine irregularities that have been shown to increase immune activation, viral replication, and T cell dysfunction.MethodsWe analysed ex vivo plasma samples from 17 HIV negative and 16 HIV pulmonary tuberculosis co infected cases using Luminex assay to see impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients before and after anti Tuberculosis treatment.ResultsThe median plasma level of IFN-γ, IL-4, MCP-3, MIP-1β and IP-10 was significantly different (P < 0.05) before and after treatment in HIV negative TB patients but not in HIV positive TB patients. There was no significant difference between HIV positive and HIV negative TB patients (P > 0.05) in the plasma level of any of the cytokines or chemokines before treatment and anti TB treatment did not change the level of any of the measured cytokines in HIV positive tuberculosis patients. The ratio of IFN-γ/IL-10 and IFN-γ/IL-4 showed a significant increase after treatment in HIV negative TB cases but not in HIV positive TB cases which might indicate prolonged impairment of immune response to TB in HIV positive TB patients as compared to HIV negative tuberculosis patients.ConclusionsHIV positive and HIV negative Tuberculosis patients display similar plasma cytokine and chemokine pattern. However, anti TB treatment significantly improves the Th1 cytokines and level of chemokines but does not restore the immune response in HIV positive individuals.

Sharps injuries and exposure to blood and bloodstained body fluids involving medical waste handlers

Exposure to healthcare waste can result in disease or injury. Though much attention is paid to the safety of healthcare professionals and their protection from sharps injury and exposure to blood and bloodstained body fluids (BBFs), the welfare and safety of non-healthcare professionals who are collecting, transporting and disposing waste has received very little attention. The objective of this study was to understand the incidence of sharps injury and occupational BBF exposure of mucous membranes involving medical waste handlers (MWHs). A cross-sectional study was carried out using a self-administered questionnaire, observation and interview. Data analysis was performed using SPSS version 16. The χ2 value was calculated and P <0.05 was considered statistically significant. One or more incidents of sharps injuries and BBF exposures to mucous membranes occurred among 42.1% and 67.5% of MWHs respectively. None of the respondents was immunized with hepatitis B vaccine owing to the high cost of immunization and absence of free universal availability of the vaccine for the adult population. Less than 50% of MWHs wore either gloves or boots while performing their activities. Even though all knew about HIV, most of the respondents demonstrated a lack of knowledge regarding viral hepatitis. The risk of sharps injury and BBF exposure appeared high in MWHs. The establishment of safe waste-management techniques and the appropriate use of personnel protective equipment among MWHs in Addis Ababa is urgently required.

Parasitic infection may be associated with discordant responses to QuantiFERON and tuberculin skin test in apparently healthy children and adolescents in a tuberculosis endemic setting, Ethiopia

BackgroundM. tuberculosis remains one of the world’s deadliest pathogens in part because of its ability to establish persistent, latent infections, which can later reactivate to cause disease. In regions of the globe where disease is endemic, as much as 50% of the population is thought to be latently infected, complicating diagnosis and tuberculosis control. The tools most commonly used for diagnosis of latent M. tuberculosis infection are the tuberculin skin test and the newer interferon-gamma release assays, both of which rely on an antigen-specific memory response as an indicator of infection. It is clear that the two tests, do not always give concordant results, but the factors leading to this are only partially understood.MethodsIn this study we examined 245 healthy school children aged from 12 to 20 years from Addis Ababa, a tuberculosis-endemic region, characterised them with regard to response in the tuberculin skin test and QuantIFERON™ test and assessed factors that might contribute to discordant responses.ResultsAlthough concordance between the tests was generally fair (90% concordance), there was a subset of children who had a positive QuantIFERON™ result but a negative tuberculin skin test. After analysis of multiple parameters the data suggest that discordance was most strongly associated with the presence of parasites in the stool.ConclusionsParasitic gut infections are frequent in most regions where M. tuberculosis is endemic. This study, while preliminary, suggests that the tuberculin skin test should be interpreted with caution where this may be the case.

Antimicrobial susceptibility pattern of nasal Staphylococcus aureus among Dessie Referral Hospital health care workers, Dessie, Northeast Ethiopia

BACKGROUND Staphylococcus aureus is a major pathogen in skin and soft tissue infections. Methicillin-resistant S. aureus (MRSA) is prevalent in most of the countries in which it is sought. MRSA is one of the important pathogens implicated in hospital-acquired infections. The main objectives of this study were to determine the antimicrobial susceptibility pattern of S. aureus isolates, the prevalence of MRSA, and the nasal carriage rate in healthy hospital staff members. METHODS A total of 118 health care workers (HCWs) were enrolled using a cross-sectional study design. Nasal swabs were collected and cultured on mannitol salt agar (MSA). The slide coagulase test was performed. Susceptibility testing was carried out on Mueller-Hinton agar using the modified Kirby-Bauer disk diffusion method with 10 antibiotics. RESULTS Of the 118 HCWs, 34 had S. aureus and 15 had MRSA, with overall positivity rates of 28.8% and 12.7%, respectively. None of the S. aureus isolates were sensitive to penicillin. MRSA isolates were resistant to commonly available antibiotics. Only two (13.3%) of the nasal isolates were vancomycin-resistant. CONCLUSIONS A high rate of nasal carriage and multidrug-resistant S. aureus was found in this study, indicating the need for standard infection control to prevent transmission in our health care setting.