Browsing by Author "Merid Yared"

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    Assessment of Disinfectant and Antibiotic Resistant Bacteria in Hospital Wastewater, South Ethiopia
    (Addis Ababa University, 2011-05) Fekadu Sintayehu; Gebre Selassie; Merid Yared
    Background: Large quantities of antibiotics and disinfectants are used in hospitals for patient care and disinfection process, respectively. These products are partially metabolized and residual quantities reach hospital wastewater, exposing bacteria to wide range of biocides that could act as selective pressure for development of resistance. Objectives: The aim of the study was to assess disinfectant and antibiotic resistant bacteria in Yirg Alem and Hawassa hospitals effluents. Methods: A cross-sectional study was conducted from December 2010-February 2011 in hospital wastewater. A total of 24 composite samples were collected on weekly basis for bacteriological analysis and susceptibility testing. Indicator organisms, pathogenic and potentially pathogenic bacteria were determined and isolated on selective bacteriologic media. Disinfectant activity was evaluated in use-dilution for tincture iodine, sodium hypochlorite and 70% ethanol and MIC was determined by agar dilution method. Similarly antibiotic susceptibility test were performed using Kirby-Bauer disk diffusion method. All methods were used according to standard methods for examination of water and wastewater. Results: Pathogenic (Salmonella, Shigella and S. aureus) and potentially pathogenic (E. coli) bacteria were detected from effluents of both hospitals. Activity of disinfectant in use-dilution demonstrated tincture-iodine as the most effective agent, followed by sodium hypochlorite and the least active was 70% ethanol. MIC for ethanol against S. aureus and gram negative rods from Yirg Alem hospital (YAH) showed 4 and 3.5 log reduction, respectively. Similarly 3.8 and 3.2 log reduction were observed for S. aureus and gram negative rods from Hawassa University Referral Hospital (HURH), respectively. Salmonella isolates from YAH effluent were resistance to Ceftriaxone, Tetracycline and Doxycycline, whereas from HURH effluent were resistant to the above three antibiotics and Gentamycin too. S. aureus from YAH effluent was resistant to Penicillin, Ampicillin and Amoxicillin, whereas from HURH was resistant to the above three antibiotics and Gentamycin too. Conclusion: Hospital effluents tested contain antibiotic resistant bacteria which are released to receiving water bodies resulting in huge public health threat. Key words: antibiotics, biocides, disinfectants, heterotrophic count, hospital effluent, hospital influent, indicator, minimum inhibitory concentration, most probable number
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    Transmission Dynamics of MYCOBACTERIUM TUBERCULOSIS IN Southern Region of Ethiopia
    (Addis Ababa University, 2020-01) Merid Yared; Woldeamanuel Yimtubezinash
    Background: Tuberculosis (TB) is a major global public health problem with countries in sub-Saharan Africa (SSA) including Ethiopia being most affected by the disease. Understanding the epidemiology of TB and the development and spread of drug-resistant TB is limited by scarce molecular epidemiologic data in SSA including Ethiopia. In terms of epidemiology of TB, control of TB in prisons is an important public health priority. In some settings, prisons have been recognized as a reservoir and sites of transmission for TB. Additionally, the spread of TB in rural settings deserves further attention. In rural settings,several factors may contribute to enhanced transmission of TB including either missed diagnosis or delays in diagnosis. Objective: To describe the molecular epidemiology and drug resistance pattern of TB to better understand the transmission of TB and the development and spread of drug resistance in different settings of Southern Ethiopia. Methods: Three studies were conducted, all using a cross-sectional design: a prison study in Hawassa Prison, a health facility-based study at nine health facilities in and around Shashemene areas of Western Arisi Zone (Oromia region) and a community-based study in the rural areas of Hawassa Zuria Woreda (Sidama Zone, Southern Region). In the prison study, incarcerated individuals were screened for TB using a symptom screen; those with a cough of ≥2 weeks had spot and morning sputum samples collected for AFB smear microscopy and molecular diagnostic testing (Xpert MTB/RIF). The study was conducted from June 15 through July 13, 2015. The health facility study was conducted among sputum smear positive patients with TB visiting nine diagnostic facilities in Southern Ethiopia. Three consecutive sputum samples (spot-morning-spot) per patient were examined using AFB smear microscopy with all smear positive specimens also having AFB cultures performed. Mtb isolates had drug susceptibility testing (DST) performed using the indirect proportion method and were genotyped with RD9 deletion typing and spoligotyping. Spoligotyping International Types (SIT) and sub-lineages (clades) were assigned according to the SITVITWEB data base. Geographic information system (GIS) was used to map source sites of strains. Whole genome sequencing (WGS) was done on selected Mtb isolates. The study was conducted from June 2015 to May 2016. The population-based survey was conducted in six Kebeles (the lowest administrative units) of Hawassa Zuria Woreda using a community-based active case finding (ACF) strategy. Volunteer women community workers led a symptom screening program to identify community members with TB. Individuals with cough ≥ 2 weeks were asked to provide two sputum samples (spot and morning) for diagnostic testing for TB. AFB smear microscopy and culture and Xpert MTB/RIF were performedThe study was conducted from May 08, 2016 through June 09,2016. Results: Among 2068 prisoners, 372 (18%) had a positive cough screen. The median age of these 372 persons was 23 years, 97% were male and 63% were from urban areas. Among them, 8/372 (2%) had a positive AFB sputum smear microscopy result and 31/372 (8%) had a positive Xpert TB/RIF. The point prevalence of pulmonary TB at the prison was 1748 per 100,000 population as defined by Xpert TB/RIF. In the health facility study, among 250 newly diagnosed patients with TB, 154 (52%) were male and 143 (57%) came from rural areas. The prevalence of HIV co-infection was 4%. A total of 230 isolates were obtained from 250 sputum cultures. All 230 isolates were M. tuberculosis strains belonging to three lineages: Euro-American, 187 (81%); East-African-Indian, 31 (14%); and Lineage 7 (Ethiopian lineage), 8 (4%). The 230 isolates could be categorized into 65 different spoligo type patterns, of which 36 (55.0%) were already known in the international data base and 29 (45.0%) were new patterns (orphans). The dominant spoligo types were SIT149(21%), SIT53 (19%) and new strains (16%). One hundred ninety-three (84%) isolates were clustered into 29 spoligotype patterns and the remaining (37, 16%) strains fell into single spoligotypes, and clustering of strains by geographic locations was observed. DST revealed that 14% of Mtb isolates tested were resistant to > 1 first line anti-TB drugs and 11% to isoniazid. SIT 149 was the most prevalent
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    Validation of the Bleach Methods for the Diagnosis of Pulmonary Tuberculosis
    (Addis Ababa University, 2007-07) Merid Yared; Kumar Raja; Aseffa Abraham
    Bacteriological diagnosis of tuberculosis is largely dependent on direct microscopy of sputum smears. It is the most widely available diagnostic test, especially in developing countries where the other options are usually not practical due to the limited resources available. However, its sensitivity is not optimal when used in control programs, usually ranging from 8.8% to 46.4% in most African laboratories. The sensitivity of the technique is further undermined in areas with high HIV prevalence. If sensitivity could be improved, the method has the potential to become an even more valuable tool for National TB Control Programs. Treating the sputum with house bleach (NaOCl) has been reported to increase sensitivity of direct microscopy. Therefore, the aim of this study was to compare the diagnostic performance of the three different bleach methods reported so far: centrifugation, overnight sedimentation and short term bleach digestion (30 min), with conventional direct microscopy and validate against culture as a gold standard on a given group of specimens. This cross sectional study was conducted at Awassa Health Center and Bushulo Major Health Center in Awassa. Five hundred (500) consecutive new TB suspects presenting at the health facilities during July to December, 2006 were enrolled in the study. Direct smears were prepared and stained using Ziehl-Neelsen technique and specimens were decontaminated and inoculated onto Lowenstein-Jensen media for culture. The left over sputum samples were pooled, equal amount of bleach was added and then divided in three portions for the three bleach treatment techniques. Smears were prepared after centrifugation, overnight sedimentation and short term digestion. The direct and bleach treated smears were read blindly by two independent microscopists. Ten percent of the negative and 20% of all the positive smears were retained for quality control. Smears were graded using the WHO/IUATLD scale. Considering smears graded scanty (<10 Acid-fast bacilli per 100 fields) as negative, the direct smear was positive in 21%, short term digestion in 20%, overnight sedimentation in 23%, centrifugation in 31% and culture in 47%. The sensitivity of direct smear microscopy under the experimental condition was 41.9%. Among the bleach techniques, sensitivity was best for centrifugation (54.6%) followed by overnight sedimentation (43.7%) and short term digestion (38.9%). The bleach centrifugation method can clearly X increase the sensitivity of smear microscopy and would thus be a useful tool to improve case detection in the National Tuberculosis Programme. Key words: tuberculosis, diagnosis, bleach methods, validation