EFFICACY OF ANTIMICROBIAL ACTIVITY OF GARLIC EXTRACTS ON BACTERIAL PATHOGENS COMMONLY FOUND TO CONTAMINATE MEAT.

BACKGROUND: Meat is amajor source of food and raw materials for a number of industries, yet a lot of meat is wasted each year due to deterioration as a result of spoilage by microorganisms such as Pseudomonas, Acinetobacter, Moraxella, Bacillus, Campylobacter, Escherichia, Listeria, Clostridium, Salmonella and Staphylococcus species. OBJECTIVE: To determine efficacy of antimicrobial activity of garlic extracts on bacterial pathogens commonly found to contaminate meat. DESIGN: A cross sectional study. SETTING: The Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine University of Nairobi. SUBJECTS: Garlic from Nganoini farm in Laikipia County, Kenya. RESULTS: The results indicated that garlic absolute ethanol extract had the highest efficacy of antimicrobial activity inhibiting all test micro-organisms. CONCLUSION: Ethanolic extract can be used as a meat preservative or decontaminant.

Streptomycin and chloramphenicol resistance genes in Escherichia coli isolates from cattle, pigs, and chicken in Kenya.

The aims of this study were to determine the genetic basis of streptomycin and chloramphenicol resistance in 30 Escherichia coli isolates from food animals in Kenya and the role of plasmids in the spread of the resistance. Seven of the 29 streptomycin-resistant isolates harbored both the strA and strB genes. Twenty-one of isolates had the strA, strB, and aadA1 genes. The strA gene was disrupted by a functional trimethoprim gene, dfrA14 in 10 of the 21 isolates harboring the three streptomycin resistance genes. Physical linkage of intact strA and sul2 genes was found in two different plasmids from four isolates. Linkage of cassette-borne aadA1 and dfrA1 genes in class 1 integrons was found in two of the isolates. Chloramphenicol resistance was due to the gene catA1 in all the chloramphenicol resistant isolates. The strB, strA, and catA1 genes were transferable by conjugation and this points to the significance of conjugative resistance plasmids in the spread and persistence of streptomycin and chloramphenicol resistance in food animals in Kenya.

Antimicrobial resistance in Salmonella serotypes isolated from slaughter animals in Kenya.

OBJECTIVES: To isolate Salmonella from food animals and characterise the antimicrobial resistance of the isolates. DESIGN: A random sampling of slaughter animals was carried out. SETTING: Department of Public Health, Pharmacology and Toxicology, University of Nairobi, Kenya and Institute for Animal Breeding, Neustadt-Mariensee, Germany. SUBJECTS: Two hundred and eighty five samples, including faecal samples and carcass, cloacal and pharyngeal swab samples were analysed. RESULTS: Sixteen (5.6%) of 285 samples were positive for Salmonella. The prevalence of Salmonella on pig carcasses (19%) was higher than in faeces (8.6%). Three Salmonella enterica sub-species enterica serovars, namely Saintpaul (S. Saintpaul), Braenderup (S. Braenderup), and Heidelberg (S. Heidelberg), were identified, with S. Saintpaul being the predominant serovar. Antimicrobial resistance was found in 35.7% of all the isolates. The S. Heidelberg isolates were susceptible to all the antimicrobial agents tested. Multidrug resistance was found in 7.1% of the resistant Salmonella isolates. Plasmids were only detected in S. Heidelberg. Ampicillin resistance was based on expression of a bla(TEM) gene, while chloramphenicol, streptomycin, and tetracycline resistances were encoded by the genes catAl, strA, and tet(A), respectively. CONCLUSION: Pigs may serve as reservoirs of antimicrobial resistant Salmonella and slaughterhouse cross-contamination of pork may be a food safety risk. We recommended that slaughterhouse hygiene be improved to minimise contamination of pig carcasses.

Risk factors associated with contagious caprine pleuro-pneumonia in goats in pastoral areas in the Rift Valley region of Kenya.

A cross-sectional study to determine risk factors associated with sero-prevalence of contagious caprine pleuro-pneumonia (CCPP) in goats was carried out between the months of March, 2014 and March, 2015 in Pokot East, Turkana West and Kajiado Central Sub-counties. A semi-structured questionnaire focusing on risk factors for CCPP was completed for each flock whose serum samples were collected. A logistic regression model was developed to assess the association between the risk factors and CCPP sero-positivity. Of the 54 flocks, 49 (90.7%) presented at least one sero-positive animal. Two hundred and four of the 432 goats tested sero-positive at monoclonal antibody based competitive Enzyme-linked immuno-sorbent assay (c-ELISA), hence a sero-prevalence of 47.2% (95% CI=42.5- 51.9). Previous exposure of flocks to CCPP (p<0.001, OR=52.8; CI=6.45, 432), distant sources of veterinary drugs (p<0.001, OR=6.17; CI=3.41, 11.1), movement of goats to dry season feeding areas (p<0.001, OR=4.31; CI=2.39, 7.75) and markets as a source of new introductions to the flock (p=0.033, OR=1.86; CI=1.05, 3.27) were identified as risk factors significantly associated with CCPP sero-prevalence. The findings provide further evidence supporting the high prevalence and endemic state of the disease in pastoral flocks and hence there is need for adequate measures to be put in place to control the disease effectively.

Prevalence of enterotoxigenic Bacillus cereus and its enterotoxins in milk and milk products in and around Nairobi.

OBJECTIVES: To determine the prevalence of enterotoxigenic Bacillus cereus (B. cereus) and enterotoxins in milk and milk products. DESIGN: A random sampling of milk products was carried out. SETTING: Market milk and milk products were collected from retail shops in Nairobi and analysed for contamination with enterotoxigenic B. cereus and its enterotoxins using reverse passive latex agglutination and TECRA ELISA immunoassay tests. SUBJECTS: Ninety six milk samples including 36 raw milk, 42 pasteurised milk, 10 yogurt and eight fermented milk samples. Forty seven Bacillus cereus isolated from milk and milk products. MAIN OUTCOME MEASURES: Isolation of enterotoxigenic B. cereus from milk and milk products and detection of B. cereus hemolytic (hemolysin BL) and non-hemolytic enterotoxins in milk. RESULTS: Fifty seven percent of the samples were contaminated with B. cereus. Eighty one percent (38 out of 47) of the isolates produced non-hemolytic enterotoxins, while 25 (53.2%) of the isolates produced hemolysin BL. Eighteen (38.3%) of the isolates produced both hemolysin BL and non-hemolytic enterotoxins. About fourteen percent (14.3%) of the pasteurised milk samples tested positive for non-hemolytic enterotoxin. CONCLUSION: Enterotoxigenic B. cereus and enterotoxins occur in market milk and their presence poses a potential risk of causing food poisoning. The risk can be reduced if milk products undergo thorough quality control checks and are always kept at below 4 degrees C till consumption. Post pastuerisation contamination which is commonly blamed for spoilage of milk products by B. cereus is not necessarily the most important source of this organism.

Immunoassay and polymerase chain reaction techniques for detection of enterotoxigenic Bacillus cereus.

OBJECTIVES: To compare the Reverse Passive Latex Agglutination (RPLA) and Enzyme Linked Immunosorbent Assay (ELISA) techniques with a Polymerase Chain Reaction (PCR) for detection of enterotoxigenic Bacillus cereus. DESIGN: A cross-sectional study. SETTING: The Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi. SUBJECTS: Forty seven Bacillus cereus strains previously isolated from foods. MAIN OUTCOME MEASURES: Detection of hemolysin BL, non-hemolytic enterotoxin, binding protein gene (hblA) of the hemolysin BL, and binding protein gene (nheA) of nonhemolytic enterotoxin. RESULTS: Twenty five (53.2%) of the isolates produced hemolysin BL, while 81% of them produced non-hemolytic enterotoxin. Thirty eight (38.3%) produced both hemolysin BL and non-hemolytic enterotoxin. A polymerase chain reaction amplification assay detected the presence of hblA gene in all hemolysin BL positive isolates and nheA gene in 91.5% of non-hemolytic enterotoxin positive isolates. There was a strong association between PCR test and RPLA test (Pearson's X2 = 12.65; p < 0.001) as well as between PCR test and visual immunoassay test (Pearson's chi-square X2 = 18.46: p < 0.01). CONCLUSION: Polymerase chain reaction amplification assay technique for detection of enterotoxigenicity of B. cereus compare well with the immunoassay tests. The technique is sensitive detecting even strains with silentgenes, and is rapid with the test complete within 24 hours.

Bacillus cereus may produce two or more diarrheal enterotoxins.

Bacillus cereus strains were tested for production of diarrheal enterotoxin by the reverse passive latex agglutination test and for presence of B. cereus enterotoxin gene (bceT) by polymerase chain reaction. About 50% of 56 B. cereus strains reacted positive in broth culture in the reverse passive latex agglutination test, while the bceT gene was detected in 41.1%. Sixteen percent of the strains were positive for both diarrheal enterotoxin and bceT gene. A 741 bp probe prepared from the polymerase chain reaction product detected bceT gene in all strains that were positive with the polymerase chain reaction. This study indicates a likelihood of two or more enterotoxins being produced by B. cereus which may be involved in causing diarrheal type food poisoning.

The prevalence and economic importance of bovine fasciolosis in Kenya--an analysis of abattoir data.

A retrospective study covering a period of 10 years (1990-1999) was carried out using post mortem meat inspection records at the Veterinary Department Headquarters at Kabete to determine the prevalence and economic importance of bovine fasciolosis in Kenya. Meat inspection records from abattoirs in 38 districts distributed over seven out of the eight provinces of Kenya were examined. Prevalence of fasciolosis was calculated as the number of cattle found to be infected with Fasciola, expressed as a percentage of the total number of cattle slaughtered. Using the average weight and market price of a bovine liver, the monetary loss occasioned by condemnation of Fasciola infected livers was calculated. A survey was also carried out at Dagoretti slaughterhouse complex in Nairobi to determine the relative occurrence of F. gigantica and F. hepatica in slaughtered cattle. Cattle slaughtered at Dagoretti slaughterhouse originate from all parts of the country. A total of 5,421,188 cattle were slaughtered in the seven provinces of Kenya during the 10-year period and 427,931 (8%) of these cattle were infected with Fasciola. The region with the highest prevalence of fasciolosis was Western Province (16%) followed, in descending order, by Eastem Province (11%), Nyanza Province (9%), Rift Valley Province (8%), Central Province (6%), Nairobi Province (4%) and Coast Province (3.5%). The total economic loss incurred by the country during the 10-year period as a result of condemnation of the infected livers was approximately US$2.6 million. The total annual economic losses during this period ranged from approximately US$0.2-0.3 million. The highest total economic losses for the 10-year period were recorded in Western Province (US$0.8 million) and Central Province (US$0.7 million). A total of 1584 cattle originating from five provinces of Kenya were slaughtered at Dagoretti slaughterhouse over a period of two months of which 147 (9.3%) were infected with liver flukes. All the liver flukes obtained from the infected livers were identified as F. gigantica. It is concluded that fasciolosis is prevalent in cattle in all provinces of Kenya, that it causes great economic losses as a result of condemnation of infected livers, and that F. gigantica is the main species of liver flukes affecting cattle in Kenya. Local climatic factors, cattle trade, rustling and population numbers, and the presence of the snail intermediate hosts are probably the main factors influencing the incidence of the disease in the various regions of the country.

Antibiotic residues in milk received by dairy cooperative societies in Kiambu district, Kenya.

A survey of antibiotic inhibitors in milk received by dairy cooperative societies in Kiambu district was done qualitatively using microbiological assay method. No antibacterial inhibitors were detected in all the samples tested. Informal discussions indicated a high level of awareness of the withdrawal requirement of veterinary drugs after animal treatment in both farmers and the management staff of dairy cooperative societies. The results show that milk from this area is free of antibiotic residues and farmers could be adhering to the withdrawal requirement of veterinary drugs. Such milk therefore does not pose a risk to the public and dairy industry.

Beef and dressed chickens as sources of enterotoxigenic Staphylococcus aureus in Nairobi.

Staphylococcus aureus (S. aureus) isolates from beef carcasses, minced beef, and dressed chicken were assayed for production of enterotoxin A, B, C and D using reverse passive agglutination technique. The highest isolation rate was from chickens followed by minced beef. Chickens yielded the highest percentage of enterotoxigenic strains. Staphylococcal enterotoxin C (SEC) was the most frequently produced type from all the three sources while enterotoxin A ranked second and enterotoxin B third. These data show that chickens and minced beef are potential sources of food poisoning staphylococci in Kenya, and that increased handling of the products increases contamination suggesting that man is the major source.

Raw milk as a source of enterotoxigenic Staphylococcus aureus and enterotoxins in consumer milk.

Staphylococcus aureus strains were isolated from 183 of 300 raw milk samples collected at the Kenya Co-operative Creamery (Dandora). 97 of these 183 trains were assayed for the production of enterotoxin A, B, C and D. Seventy two (74.2%) of these were found to produce either a single or a combination of enterotoxins. Raw milk is a potential source of enterotoxigenic S. aureus in milk and milk products, especially if there is defective pasteurisation.

Frequency of antimicrobial resistance and plasmid profiles of Escherichia coli strains isolated from milk.

Susceptibility to eight commonly used antimicrobial agents and plasmid profile analysis was done on forty one Escherichia coli strains isolated from milk. Most (95%) of the strains were resistant to sulphamethoxazole with a relatively low rate of resistance to the other antimicrobial agents. Twenty nine per cent of the isolates showed multiple resistance. The number of plasmids carried per strain was between 1 and 5, while plasmid sizes ranged between 107 and 1.0 megadaltons (MDa). There was no relationship between carriage of plasmids and antimicrobial resistance patterns.

Coliform counts and Escherichia coli in raw commercial milk from dairy farmers in Kiambu District, Kenya.

The rate of contamination with coliforms and incidence of Escherichia coli (E. coli) in raw milk supplied by farmers to dairy cooperative societies for marketing was investigated. About forty two (42.2%) percent of the milk samples from farmers cans and 10.3% of samples from cooperative cans were found to be free of coliforms, while 89.5% of the samples from farmers cans and 50% samples from cooperative cans could be considered to be of good quality with no more than 50,000 coliforms/ml of milk. Forty two E. coli strains were isolated from milk samples, five of which were found to be enteropathogenic, while none was found to be of serogroup O157. The results indicated that a good number of farmers draw milk under satisfactory conditions, but awareness campaigns on clean milking, milk handling and storage practices should be stepped up in order to reach farmers who may not be informed. Again the study showed that raw milk can get contaminated with enteropathogenic strains of E. coli that can pose a potential risk to humans, thus calling for extra care when preparing milk and milk products that are to be consumed by human beings.

Molecular epidemiology of Bacillus cereus food poisoning.

OBJECTIVES: To investigate the potential use of DNA techniques in epidemiological diagnosis of Bacillus cereus food poisoning. SUBJECTS: Fifty six B. cereus isolates from milk were studied. DESIGN: The 56 B. cereus isolates were characterised into enterotoxin positive (27 isolates) and enterotoxin negative (29 isolates) using reverse passive latex agglutination technique. SETTING: Plasmid and genomic DNA were isolated from all the B. cereus isolates. The plasmid DNA was analysed by gel electrophoresis, while genomic DNA was used for restriction endonuclease and toxin gene analyses. MAIN OUTCOME MEASURES: Plasmid profile analysis, restriction endonuclease analysis of genomic DNA, and test for bceT and hblA genes by polymerase chain reaction and gene probing. RESULTS: Seventy two per cent of the isolates contained one to five plasmids of molecular sizes between 0.1 to 60 mDa. Restriction analysis of genomic DNA gave different restriction patterns among enterotoxin positive and enterotoxin negative isolates. A polymerase chain reaction assay detected bceT gene in 41.1% of the isolates, 16% of which tested positive for enterotoxin with B. cereus enterotoxin reverse passive latex agglutination (BCET-RPLA) kit, while hblA gene was detected in all the enterotoxin positive isolates. BceT and hblA gene probes detected the respective genes in all the isolates that also tested positive for toxin genes by polymerase chain reaction. CONCLUSION: DNA techniques provide an alternative approach to the diagnosis of enterotoxigenic B. cereus.

Foodborne diseases in Kenya.

OBJECTIVES: To determine the occurrence of foodborne disease outbreaks in Kenya and the efforts employed to combat them. DESIGN: Cross-sectional survey. SETTING: Forty two districts in Kenya between 1970 and 1993. STUDY SUBJECTS: Foodborne disease outbreak episodes due to Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum, Bacillus cereus, Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica, Listera monocytogenes, chemicals, aflatoxin, plant and animal poisons. OUTCOME MEASURES: Number and aetiological causes of foodborne disease outbreaks reported in the study period. RESULTS: Thirty seven food poisoning outbreaks were reported to the Ministry of Health from various parts of the country in the study period 1970 to 1993, and only 13 of these involving a total of 926 people were confirmed to be due to particular aetiological agents. Foods that were involved included milk and milk products, meat and meat products, maize flour, bread, scones and other wheat products, vegetables and lemon pie pudding. A high number of food poisoning cases were treated as outpatients in various health facilities. CONCLUSION: Under-reporting, inadequate investigation of outbreaks and inadequate diagnostic facilities suggest that foodborne disease outbreaks are more than is recorded by the Ministry of Health.

Antimicrobial resistance patterns and plasmid profiles of Staphylococcus aureus isolated from milk and meat.

OBJECTIVES: To determine the frequency of resistance of Staphylococcus aureus to various antimicrobial agents, and the relationship between antimicrobial resistance of the isolates and carriage of plasmids. DESIGN: A random sampling of milk and meat samples was carried out. SETTING: Milk was collected from various dairy co-operative societies in Nairobi and Kiambu districts. Minced meat samples were purchased from various outlets in the city of Nairobi. SUBJECTS: Ninety six Staphylococcus aureus isolates from milk (seventy five isolates) and minced meat (twenty one isolates) samples. MAIN OUTCOME MEASURES: Plasmid profiles and antimicrobial susceptibility tests to ampicillin, lincomycin, penicillin, erythromycin, methicillin, minocycline, cotrimoxazole and chloramphenicol. RESULTS: Seventy one per cent of the isolates carried between one and six plasmids of molecular sizes ranging from 0.1 to 14.5 kilobases. High frequency of resistance was observed with lincomycin (67.7%), penicillin (66.7%) and cotrimoxazole (51%). A high percentage (76%) of isolates were susceptible to minocycline followed by erythromycin (57.3%). Most (80.2%) of isolates were multiply resistant to between two and six antibiotics. CONCLUSION: Most Staphylococcus aureus isolates were multiply resistant to various antimicrobial agents, but there was no apparent relationship between carriage of plasmids and antimicrobial resistance. Milk and meat may contain resistant Staphylococcus aureus posing a potential risk to consumers.

Frequency of antimicrobial resistance and plasmid profiles of Bacillus cereus strains isolated from milk.

Plasmid profile analysis and susceptibility to eight commonly used antimicrobial agents was done on sixty Bacillus cereus (B. cereus) strains isolated from milk. About seventy two percent (71.7%) of the isolates contained plasmids. The number of plasmids per isolate ranged between 1 and 5, while plasmid sizes ranged between 60 and 0.1 megadaltons (Mda). All isolates were resistant to ampicillin with a relatively high rate of resistance to cotrimoxazole and sulphamethoxazole. The isolates showed a low frequency of resistance to the other antimicrobial agents, with all of them being susceptible to streptomycin. Approximately ninety one (90.7%) percent of the isolates showed multiple resistance. There was no apparent relationship between carriage of plasmids and drug resistance.

Toxin production and antimicrobial resistance of Escherichia coli river water isolates.

OBJECTIVES: To establish the types of E. coli isolates that are found in river water around Nairobi and to assess the potential risk of use of this water to human health. DESIGN: Multiple stratified sampling was carried out. Surface sampling was used in the entire study. SETTING: The study was carried out on river waters surrounding Nairobi, Kenya. SUBJECTS: Forty Escherichia coli strains isolated from river water. MAIN OUTCOME MEASURES: Serotyping, toxin gene tests and susceptibility to tetracyclines, ampicillin, chloramphenicol and kanamycin were analysed. RESULTS: None of the isolates could be specifically serotyped using the available antisera. Toxin gene production tests using the colony hybridisation technique revealed that nine (22.5%) of the strains were positive for heat stable (ST) toxin, seven (17.5%) to the heat labile (LT) toxin and two (5%) to both. Using the Agar Disk Diffusion technique, eighty per cent of the strains were susceptible to all four antibiotics, while twenty per cent of the strains showed multiple resistance. None of the strains was resistant to all four antibiotics while no strain showed resistance to kanamycin. CONCLUSION: None of the E. coli isolates was serotypable and it was therefore not possible to determine whether serologically identical strains of ETEC were haboured by man or animals. Toxin gene tests results showed that there is some risk of infection by diarrhoea causing ETEC to man and animals. Toxin gene tests results showed that there is some risk of infection by diarrhoea causing ETEC to man and animals if they consume this water untreated and there is evidence to show resistance of bacteria to antibiotics, hence appropriate health measures should be adhered to.