Browsing by Author "Ashenafi, Mogessie (Professor)"

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    Cockroach-Associated Food-Borne Bacterial Pathogens from Some Hospitals and Food Handling Establishment in Addis Ababa
    (Addis Ababa University, 2004-06) Tachbele, Erdaw; Ashenafi, Mogessie (Professor); GebreMichael, Teshome(PhD)
    A study was carried out to determine the role of cockroaches as reservoirs and vectors of food-borne bacterial pathogens in some hospitals and food handling establishments in Addis Ababa. A total of 1600 adult cockroaches were captured aseptically from eight study sites between December 2002 and June 2003, and all were identified as Blattella germanica. Ten cockroaches were pulled as one sample from each of the eight study areas and killed with chloroform. Using selective media, their external surface wash and internal (gut) homogenates, after adequate decontamination of the extemal surface, were culturally examined for the presence of Salmonella, Shigella, Escherichia coli 0157:H7, Staphylococcus aureus and Bacillus cereus. We have also initiated challenge studies to evaluate survival and excretion of Salmonella B, Shigella B, and Staphylococcus aureus in B. germanica following ingestion of 10 6 CFU/g of contaminated food. In the process of isolation and identification of the test pathogens, 12 Salmonella spp., 2 Shigella B, 2 E. coli 0157, 17 S. aureus and 25 B. cereus isolates were made. Furthermore, most of the isolates were resistant to two or more antimicrobial drugs in a susceptibility test. In the challenge experiment, cultural examination of fecal pellets showed that Salmonella and S. aureus could be excreted for 35 and 14 days post infection, respectively. However, culture examination of fecal pellets of Shigella B infected cockroaches failed to yield the bacterium for 30 days post infection. These results indicate that cockroaches (B. germanica) are the possible reservoirs and vectors of multi-drug resistant food-borne pathogens in hospitals and food-catering areas that may be responsible for nosocomial and community acquired infections. Hence, there is a need to implement effective cockroach controlling programs focusing on hygiene. Continuous surveillance and rational use of antimicrobial drugs are also required in order to minimize the emergence and spread of drug resistant pathogenic bacteria by cockroaches. Further work is essential to establish the natural transmission of human food-bome diseases by cockroaches
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    Djstribution of Drug Resistance Among Enterococci, Salmonella and Escherchia Coli 0157:H7 Isolates from Poultry and Cattle Faeces
    (Addis Ababa Universty, 2006-05) Bekele, Behailu; Ashenafi, Mogessie (Professor)
    Surveillance of the prevalence of zonootic bacteria and resistant commensals in food animals is necessary to control the spread of the pathogens and resistant commensal bacteria to humans through contaminated animal food products and to the environment via their faecal material. This study was designed to see the prevalence of antibiotic resistance in enterococci from poultry and cattle; to asses the prevalence of Ecoli 0157 H7 from cattle, and that of Salmonella from cattle and poultry. Two hundred eighty cloacal swabs collected from poultry were examined for the presence of Salmonella and enterococci and the isolates were tested for their resistance to an array of 8 and 11 different antibiotics, respectively. Similarly, 450 fresh faecal samples collected from cattle were examined for the presence of E coli 0157 H7, Salmonella and enterococci. The Salmonella and enterococci isolates from cattle were tested for their resistance to an array of 8 and 9 different antibiotics, respectively. Entercoccus (aecium was the most dominant species in both poultry and cattle (49.6% and 34/64), followed by Enterococcus durans (26.9% and 21/64). The prevalence of Salmonella in poultry and cattle was 15.4% and 1.8%, respectively. None of the cattle faecal samples was positive for Escherichia coli 0157:H7. Resistance to the antibiotics tested was seen in all species from poultry. All E faecalis isolates showed susceptibility to amikacin. There was no significant difference among farms and species in their percentage of resistant isolates to the different antibiotics, except difference among farms in percentage mean resistant isolate for penicillin G and vancomycin (at 0=0.05). Vancomycin resistance was observed in 44% of enterococcal isolates from poultry in the four farms and in 17% isolated from cattle. Multiple drug resistance (MDR) was observed in 78.2% and 90.6% enterocccal isolates from poultry and cattle, respectively. Entercoccal isolates from cattle showed resistance with varying percentage to all antibiotics tested, except amikacin. Among the Salmonella isolates 16 from poultry and 1 from cattle showed MDR. The presence of MDR isolates in the commensal and pathogenic microbes is a serious public heath concern. The government and concerned bodies should focus and work more in the area. Key words/phrase: Antibiotic resistance, Enterococci, Escherichia coli 0157:H7, MDR, Salmonella
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    Microbiological Profile and Safety of Some Street vended Foods in Addis Ababa
    (Addis Ababa University, 1999-06) Muleta, Diriba; Ashenafi, Mogessie (Professor)
    Microbiological profiles and safety of street-vended food collected from vendors in Addis Ababa, Ethiopia were determined in 1998 and 1999. The 150 samples of foods investigated consisted of sambllssa (legume-based), cooked and sauced macaroni, lentil sandwich, kitfo (raw minced and spiced meat dish) and egg sandwich. All samples of kitfo and egg sandwich were held at temperatures that permit bacterial growth (15.5-24S C) and (15.5- 34S C), respectively. Most samples of the other food products were stored at temperature range of 15.5-34S C. In general, sambllssa had low counts of aerobic mesophilic bacteria and staphylococci. Aerobic bacterial spores, yeasts, members of Enterobacteriaceae, colifonns and Bacillus cerellS were isolated rarely in sambllssa. Highest aerobic mesophilic counts (> 108 cfb/g) were recorded in egg sandwich. The other food products contained counts as high as 107 cfu/g. Presumptive Bacillus cereus attained greatest population level in macaroni samples (> 10' cfu/g). In other dishes it had counts> 104 cfuig. Majority of the samples which were positive tor aerobic bacterial spores, coliforms, Enterobacteriaceae, staphylococci and yeasts contained >104 , 10', 105 , 105 , and 104 cfuig, respectively. In the street foods considered in this study, moulds were either detected rarely or not at all. Variations in counts among the samples of the respective street foods were obvious (CV 10%).A total of 1552 bacterial isolates were screened from foods obtained from street vendors and were characterized into various genera and bacterial groups. Gram-positive organisms predominated (76.9%) along with Staphylococcus and Micrococcus species comprising 22.8% and 15% of aerobic microflora, respectively. From Gram-negative organisms, members of a family Enterobacteriaceae (14.5%) were frequently encountered. Salmonella was recovered from samples of egg sandwich and kitfo and macaroni yielded Shigella. Challenge studies showed that the test strains, Salmonella typhimul'illlll, Shigella flexneri and Staphylococcus aureus grew in egg sandwich, kitfo and macaroni to markedly high levels. The faulty handling and serving operations, poor sanitation of the vending sites, time-temperature abuse during holding, addition of raw products either to cooked or uncooked dishes, the use of unclean multipurpose cloth and water of dubious quality (reused water) were deemed potentially hazardous. Thus, education of both vendors and consumers in basic principles of hygiene is an urgent issue by concerned bodies.
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    Microbiological Profile of Imported and Local Brands of Canned Foods in Addis Ababa
    (Addis Ababa Universty, 2006-06) Chekol, Yonas; Ashenafi, Mogessie (Professor)
    The primary objective of this study was to evaluate the microbiological quality and safety of canned foods available to consumers on the market in Addis Ababa and also to assess the fate of contaminating pathogens in the canned foods when stored at ambient and refrigerator temperature. The distribution of drug resistance among the dominant isolates was also evaluated. A total of 100 samples of canned foods comprising 20 each of, fish, meat, vegetables, milk and soups were collected from Addis Ababa super markets and shops. Date of production, expiration and ingredients of each sample were recorded. The samples were bacteriologicall y analyzed for counts of aerobic mesophilic, Staphylococcus spp, Calif arms and yeast. The pH of each sample was determined li'om the original sample. The aerobic mesophilic bacteria were dominated by, Bacillus spp, Micrococcus spp and other Gram-positive rods. Staphylococcus spp and Coliform.l· were encountered in some fish and meat canned food products. Salmonella and Shigella spp were not detected in any of the 100 samples. A total of256 aerobic spore-forming bacilli were isolated from canned foods. B. brevis, B. cereus, B. lichell(formis, B. larvae, B. /irmus. B. macerans B. pumilus alld B subtilis were the frequent isolates. Almost all Bacillus isolates were susceptible to chloramphenicol, erythromycin, gentamycin and kanamycin. Most isolates exhibited resistance to amoxycillin and ampicillin. Of the isolates tested for antibiotic sensitivity profile 139, (53%) showed multiple antibiotic resistance. Growth of Shigella j1exilleri and Salmonella Typhimurium inoculated into commercially available canned foods (meat, fish, vegetable and soup) was shldied at refrigeration and ambient temperature. In both temperatures the strains grew and multiplied luxuriously
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    Microbiological Quality and Safety of Commercially Produced Sausages in Addis Ababa
    (Addis Ababa University, 2006-06) Assaye, Hirut; Ashenafi, Mogessie (Professor)
    The microbiological quality and safety of emulsion type small diameter (frankfurter) and large diameter (mortadella) sausages purchased from different supermarkets in Addis Ababa, Ethiopia, were investigated between November, 2004 and December, 2005. A total of 210 sausage samples consisting of 120 small diameter (30 each of pork, beef, veal and chicken) and 90 large diameter (30 each of pork, veal and chicken mortadella) sausage samples were included in the study. The majority of sausages had pH values above 6.00 with mean values ranging between 6.11 and 6.33. The moisture content values of small diameter sausages ranged between 32% and 46% and those of large diameter sausages ranged between 31 % and 63%. With regard to the microbial load of small diameter sausages, more than 53% of pork, 87% of beef, 57% of veal and 40% of chicken sausage samples had aerobic mesophilic counts 2:log 5 cfu/g. Enterobacteriaceae were frequently encountered in these sausage samples and more than half of beef and veal sausage samples had Enterobacteriaceae counts 2: log 4 cfu/g. The majority of pork, beef and veal sausage samples also harbored coliforms. Furthermore, more than 40% of veal sausage samples had coliform counts 2:log 4 cfu/g. On the other hand, coli forms were rarely detected in chicken sausage samples. Enterococci were encountered in 60% of pork, 100% of beef and in more than 70% of veal and chicken sausage samples with counts ranging from log 2 to log 6 cfu/g. About 26% of pork, 60% of beef and 38% of veal sausage samples had Staphylococcus counts 2:log 5 cfu/g. All sausage samples harbored LAB and more than 73% of pork, 60% of beef and about 40% of veal sausage samples had counts 2:log 7 cfulg. Over 86% of pork, 93% of beef, 38% of veal and 31 % of chicken sausage samples had yeast counts 2: log 4 cfulg. In the case of large diameter sausages or mortadellas, about 53% of pork, 48% of veal and 40% of chicken mortadella samples had aerobic mesophilic counts 2: log 5 cfu/g, thus exceeded the typical aerobic mesophilic count value set for ready-to-eat foods. Enterobacteriaceae were encountered in more than 60% of pork, 50% of veal and 45% of chicken mortadella samples with counts between log 2 and log 4 cfu/g. More than 50% of pork and about 33% of veal and 40% of chicken mortadella samples had also coliform counts between log 2 and log 4cfu/g. The majority of large diameter sausages harbored enterococci and staphylococci. LAB were encountered in all mortadella samples and 40% of pork and more than 30% of veal and chicken mortadella samples had counts :::Iog 6 cfu/g. The majority of mortadella samples contained yeasts and more than 45% of pork, 40% of veal and 30% of chicken mortadella samples had counts::: log 4 cfu/g. The aerobic mesophilic flora of both small and large diameter sausages was dominated by Gram-positive organisms, with Bacillus being the most dominant species in both types of sausages. Salmonel/a was isolated from four (1.9%) samples consisting of two small diameter sausages and two mortadellas. During aerobic storage of small diameter sausage samples and sliced mortadella samples at ambient temperature, both types of sausages spoiled within three to four days. At refrigeration storage, small diameter sausages spoiled within 12 to 16 days and mortadella samples spoiled within 12 to 20 days of storage. Spoilage in small diameter sausage samples was manifested as slime formation and off-odor development whereas spoilage in sliced mortadella samples was manifested as green discoloration and off-odor development. In general, the majority of sausage samples investigated in this study had high microbial load. Time temperature abuse during processing or post-cooking contamination due to improper handling of the products or inadequate storage conditions or a combination of these factors may contribute to high microbial counts. Furthermore, the absence of microbiological control system or the end product, the raw material, or the other ingredients, at any stage of production and the poor sanitalY condition of some processing plants revealed inadequacies conceming quality and safety of these products. Key words/ phrases: Addis Ababa, Frankfurters, mortadella, quality, safety, Salmonel/a, sausage, supermarket
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    Microbiological Quality and Safety of Cream Filled Cakes Produced in Various Pastries in Addis Ababa and the Antimicrobial Resistance of the Pathogenic Isolates
    (Addis Ababa University, 2008-07-04) Kebede, Geda; Ashenafi, Mogessie (Professor)
    A total of 80 samples of cream cakes from ten different pastries in Addis Ababa were examined for their pH, moisture content, holding temperatures, bacteriological profile, amylolytic, proteolytic and lipolytic properties, presence of food-borne pathogens and their drug resistance pattern. The mean pH values of cream cakes from ten different pastry houses ranged from 5.43 to 6.64 and the mean moisture content ranged from 44.02% to 29.86 %. About 96.9 % of samples were stored within a temperature range of 15-25 oC. About 75.95% of the cream cakes had counts higher than log 8 cfu /g. Among bacterial strains isolated from different cream cake samples, Bacillus spp. (51.75%) dominated the microflora. Staphylococci and members of Enterobacteriaceae constituted 3.51% and 13.33 % respectively, of the microflora. About 45.85% of the isolates were amylolytic consisting mainly of Bacillus spp. About 1.85 % of them were proteolytic and none was lipolytic. This study indicated the need to train producers and handlers of cakes in basic principles of hygiene. Keeping cream cake at ambient temperatures must also be avoided.
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    Prevalence of Salmonella and Shigella Spp on Lettuce and Green Pepper and their Drug Resistance Pattern
    (Addis Ababa University, 2008-07-03) Guchi, Biniam; Ashenafi, Mogessie (Professor)
    The microbial load of lettuce and green pepper purchased from different supermarkets in Addis Ababa, Ethiopia, was analyzed. A total of 80 vegetable samples consisting of 40 lettuces and 40 green peppers were included in the study. More than 90% of the lettuce and the green pepper samples had aerobic mesophilic counts of ≥ log 6 cfu/g. Enterobacteriaceae were frequently encountered in these samples and about 97% of the lettuce and 58% of the green pepper samples had enterobacteraceae counts of ≥ log 5 cfu/g. Over 48% of the lettuce and 35% of the green pepper samples had coliform counts ≥ log 4 cfu/g. All vegetable samples harbored staphylococci and more than 92% of the lettuce samples and 80% of the green pepper samples harbored staphylococci with counts ranging from log 4 to log 6 cfu/g. About 42% of lettuce and 30% of green pepper samples had spore counts ≤ log 2 cfu/g. The majority of lettuce and green pepper samples harbored yeasts and mold and more than 88% of lettuce and 18% of green pepper samples had counts ≥ log 4 cfu/g. The aerobic mesophilic flora of both lettuce and green pepper samples were dominated by Gram positive organisms, with Bacillus and Micrococcus being the most dominant species in the lettuce and green pepper, respectively. Salmonella was isolated from six (10%) samples consisting of two lettuce and four green pepper samples. Shigella was also isolated from fifteen (18.75%) samples of five lettuces and ten green peppers samples. Resistance to antibiotics was seen in all isolates from the vegetable samples. All of the Salmonella and 97% of Shigella isolates showed resistance to penicillin. The majority of the Salmonella isolates showed susceptibility to polymixin B., gentamicin and ciproflaxin. Ampicillin resistance was observed in 42% of Salmonella and 79% of Shigella isolates. Multiple drug resistance (MDR) was observed in 8 and 24 isolates of Salmonella and Shigella isolates.
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    Prevalence of Bacterial Vaginosis, Characterization of Lactic Acid Bacteria Isolates and Patterns of Antimicrobial Test From Women Vaginal Fluid in Addis Ababa
    (Addis Ababa University, 2008-08) Aynalem, Seblewongiel; Ashenafi, Mogessie (Professor)
    The human vagina is a complex integrated environment containing an abundance of microorganism. Bacterial vaginosis (BV) is a disorder characterized by a reduction in or absence of Lactobacillus colonization, and overgrowth of several facultative and obligate anaerobic bacteria. BV has been reported as one of the most common vaginal infections in women at reproductive age from different part of the world. This study was conducted to evaluate the prevalence of BV and some associated risk factors in Addis Ababa. Moreover the study examined the composition of lactic acid bacteria (LAB) genera isolated form vaginal specimen culture and the antimicrobial sensitivity pattern of some of the isolated LAB. Among 100 women randomly enrolled in this study a BV prevalence of 32% was found based on Gram-stain scoring of vaginal flora according to Nugent criteria. The prevalence of BV was higher among women at age group 31-40 (44%), Christian women (34%), who are married (33%), non-pregnant (34%) and women who had a previous history of abortion (37%). Lactic acid bacteria (LAB) were isolated from 70% of women. Out of 350 colonies which were isolated and characterized, 40% were lactococci, 29% were lactobacilli, 23% were pediococci and 8% were leucnostoc. From a total of 60 lactic acid bacteria isolates that were subjected to antimicrobial activity test, both the most frequent resistance and the least sensitivity result was noted for Clindamycin (42% and 50% respectively), where as the most frequent sensitivity and the least resistance was recorded for Vancomicine (80% and 20% respectively). This study has provided evidence for a considerable prevalence of BV in women. Therefore, the health sector and other responsible bodies should give the concern to screening and treating women for bacterial vaginosis. On top of that creating the awareness among the society will add its value on the public health profile of women and probably would contribute to reduce the risk of acquisition of other more serious STDs. Moreover, the knowledge of lactic acid bacteria composition and pattern of antimicrobial activities of human vaginal fluid would help to design better therapies and show future directions to maintain the healthy nature of human vaginal ecosystem.
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    Some Microbiological and Biochemical Studies on the Fermentation of two Traditional Condiments,Awaze'and'Datta
    (Addis Ababa University, 1999-06) Idris, Ahmed; Ashenafi, Mogessie (Professor)
    The microbial dynamics, pH and titratable acidity together with some biochemical changes associated with the fermentation of two Ethiopian condiments, 'awaze' and 'daffa' were investigated following the traditional methods of preparation. The two condiments were prepared in the laboratmy, from a variety of vegetable and spice n:ixtures. The fermentation of both condiments is carbohydrate fermentation carried out by lactic acid bacteria with a progressive increase in titratable acidity and decline in pH. Other microorganisms isolated did not appear to playa major role in the process of fermentation, although yeasts appeared in the latter stage of 'awaze' fermentation. Lactic acid bacteria, which kept on increasing throughout the fermentation, ranged from 106 -lOll cfu/g for 'awaze' and from 104-109 f9r 'datta '. Enterobacteriacea and coliforms, which were isolated at the initial stages of 'datta' fermentation, were inhibited at 32 h. by the antimicrobial activity of the dominating lactic acid bacteria. Reducing sugar changes, detected by the DNScolorimetric method, was very significant in 'awaze' than 'datta " in which there was an initial increase, and a decline afterwards due to the utilization of sugar by the proliferating lactics. The changes associated with the protein content of the two condiments, as detected by the formol titration method, were very little.
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    Taxonomic studies on Lactobacillus and Pediococcus isolates from fermented tef (Eragrostis tej) and kocho (Ensete ventricosum) and microbiological safety of the baked products
    (Addis Ababa, 1998-06) Nigatu, Ayele; Ashenafi, Mogessie (Professor)
    Tel dough and kocho are products of typical lactic acid food fennentations. BOIh foods are the main dietary sources in Ethiopia. Lactic acid bacteria (LAB) belonging to Lactobacillus. Pediococcus and LeuconslOc are amongst the main fermentative rnicroflora in these foods. Molecular taxonomic stud ies using RAPD. DNA:DNA hybridization. 16S rR.!'lA sequencing and API 50 CH fennentation profiles were carried out on food isol ates together with type and reference strains of Lactobacillus and PediococclIs species. The results revealed (he presence of a diverse range of species in ref and kocho. Lactobacillus and Pediococcus spec ies were abundant in both foods while Weissella species were identified among kocho isolates. The use of R..<\PD was valuable for grouping lactobacilli and pediococci isolates from kocho and lei The method enabled discrimination ben .... een phenotypically inseparable pediococci. Ped. acidilaclici and Ped penrosacell.s and among type strains of Lactobacillus species. Its use might however. be limited in large number of lactobacilli isolates. DNA homology and sequence data were fo und to be supplementary and essential for efficient identification of an isolate. API 50 CH utilization profiles were influenced by incubation temperature in many strains of Lactobacillus species. Diversity and higher test vigours of isolates while utilizing different carbohydrates showed pertinent metabolic roles in fermenting ref dough and kocho. The inability of different pathogenic and spoilage bacteria to survive the fermentation processes and baking heat implied the high safety levels of the products.
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    Variablit Some Microbiol Ogical and Chemical Properties of Tej Between and Within Some Vending Houses in Addis Ababa
    (Addis Ababa University, 2000-07) Bahiru, Bekele; Ashenafi, Mogessie (Professor)
    'tej' being honey wine, is one of the primitive types of wines that are not crystal clear, but cloudy, effervescent, containing residues of substrates, the fermenting yeasts and other microorganisms. Honey wines are prepared and consumed in many parts of the world. 'tej' is consumed widely in many parts of Ethiopia and is prepared from honey, or honey and sugar, water and Gesho (Rhamnus prenoides). Roots, stems or leaves of plants are added assuming atlincrease in the alcohol content and its potency. Like any other spontaneous fermentation, 'tej', in its fermentation, relies on the microorganisms that inhabit the must from different sources. The substrates, utensils, equipment, and the envirorunent are responsible for the randomization of the micro flora. In such spontaneous fermentation and un-optimal physical and chemical conditions, variability in the product quality and stability becomes inevitable. So, investigating the variability and its extent in some microbiological and chemical properties of 'tej' at the time it was ready for consumption, was the objective of this study. At consumption stage, 'tej' was highly loaded with yeasts and Lactic acid bacteria. Members of different genera of yeasts, members of the bacterial genera of Lactobacillus, Pediococcus, Streptococcus, Leuconostoc, were isolated and identified. Of the yeast isolates, species of Saccharomyces were dominant, followed by Kluyveromyces, Debal'O/11yces, Hansel1ula, Endomycopsis and Pichia specIes. Generally, the homofermentative (52.09%) were higher in counts than the heterofennentative( 47.91 %) lactic acid bacterial population.. All the isolates from the aerobic mesophilic bacterial plates were identified as members of Baci I/lls. All the studied microbiological and chemical properties of 'te}' had significant variability among samples within each vending house. Also, except yeast and lactic acid bacterial populations and fusel oil contents, all the other microbiological and chemical properties of 'te} , studied had statistically significant variability (AN OVA, p < 0.004 for all) between the mean values of all the vending houses. Generally, all samples also showed variability in their total alcohol, total lipid, protein, and reducing sugar. Variability in fusel oil, titratable acidity and total carbohydrate was also noted. So, 'te}' at the time it was ready for consumption had statistically significant variability both within and between vending houses in the microbiological and chemical properties.