Phenotypic Characterisation of Staphylococcus aureus Isolated from Patients in Healthcare Institutions in Zaria Metropolis, Kaduna State, Nigeria.

BACKGROUND: Staphylococcus aureus is a cosmopolitan and pathogenic microorganism associated with various diseases spectra and antimicrobial resistance of public health importance. AIM: This study determined the phenotypic characteristics of S. aureus isolated from patients in healthcare institutions in Zaria metropolis. STUDY DESIGN: A cross-sectional hospital-based study was carried out in 5 healthcare institutions. Four hundred and twenty clinical samples were collected and analyzed. RESULTS: Majority of the patients (54.3%) were within the age range 21-40 years and mean age of 26.04 ± 12 years. Approximately, 70% of the respondents had history of antibiotic use prior to consultation in the hospitals and were self-prescribed, and 91.2% were outpatients. The most commonly abused antibiotics were ampicillin-cloxacillin (19.5%) and cotrimoxazole (10.0%), and the mean duration of their use was 3.5 ± 1.3 days. The detection rate for S. aureus was 10% and 5.2% for MRSA. The S. aureus isolates showed the highest frequency of resistance against ampicillin 42 (100%), followed by penicillin G 39 (92.9%) and least was to gentamicin 5 (11.9%). The frequency of resistance for the MRSA were ampicillin 22 (100%), penicillin G 21(95.5%) and least was to gentamicin 2 (9.1%). The minimum inhibitory concentrations of oxacillin were greater than 128 µg /ml. CONCLUSION: The detection rate of S. aureus and MRSA strains are of great public health concern which requires continuous health education on rational use of antibiotics among others.

CONTEXTE: Staphylococcus aureus est un micro-organisme cosmopolite et pathogène associé à divers spectres de maladies et à une résistance aux antimicrobiens d'importance pour la santé publique. OBJECTIF: Cette étude a permis de déterminer les caractéristiques phénotypiques de S. aureus isolé chez des patients dans des établissements de santé de la métropole de Zaria. PLAN DE L'ÉTUDE: Une étude transversale en milieu hospitalier a été menée dans 5 établissements de santé. Quatre cent vingt échantillons cliniques ont été recueillis et analysés. RÉSULTATS: La majorité des patients (54,3 %) étaient âgés de 21 à 40 ans et l'âge moyen était de 26,04 ± 12 ans. Environ 70 % des répondants avaient des antécédents d'utilisation d'antibiotiques avant la consultation dans les hôpitaux et étaient auto-prescrits, et 91,2 % étaient des patients externes. Les antibiotiques les plus fréquemment utilisés étaient l'ampicillinecloxacilline (19,5 %) et le cotrimoxazole (10,0 %), et la durée moyenne de leur utilisation était de 3,5 ± 1,3 jours. Le taux de détection de S. aureus était de 10 % et de 5,2 % pour le SARM. Les isolats de S. aureus ont montré la plus grande fréquence de résistance à l'ampicilline 42 (100%), suivie de la pénicilline G 39 (92,9%) et la plus faible à la gentamicine 5 (11,9%). La fréquence de résistance pour le SARM était de 22 (100%) pour l'ampicilline, 21 (95,5%) pour la pénicilline G et 2 (9,1%) pour la gentamicine. Les concentrations minimales inhibitrices de l'oxacilline étaient supérieures à 128 µg /ml. CONCLUSION: Le taux de détection des souches de S. aureus et de SARM est un grand problème de santé publique qui nécessite une éducation sanitaire continue sur l'utilisation rationnelle des antibiotiques entre autres. Mots clés: S. aureus, MRSA, phénotype, résistance aux antimicrobiens, patients d'hôpitaux, Nigeria.

Phenotypic Characterisation of Staphylococcus aureus Isolated from Patients in Healthcare Institutions in Zaria Metropolis, Kaduna State, Nigeria

BACKGROUND: Staphylococcus aureus is a cosmopolitan and pathogenic microorganism associated with various diseases spectra and antimicrobial resistance of public health importance.Aim: This study determined the phenotypic characteristics of S. aureus isolated from patients in healthcare institutions in Zaria metropolis.STUDY DESIGN: A cross-sectional hospital-based study was carried out in 5 healthcare institutions. Four hundred and twenty clinical samples were collected and analyzed. RESULTS: Majority of the patients (54.3%) were within the age range 21­40 years and mean age of 26.04 ± 12 years. Approximately, 70% of the respondents had history of antibiotic use prior to consultation in the hospitals and wereselfprescribed, and 91.2% were outpatients. The most commonly abused antibiotics were ampicillin-cloxacillin (19.5%) and cotrimoxazole (10.0%), and the mean duration of their use was 3.5 ± 1.3 days. The detection rate for S. aureus was 10% and 5.2% for MRSA. The S. aureus isolates showed the highest frequency of resistance against ampicillin 42 (100%), followed by penicillin G 39 (92.9%) and least was to gentamicin 5 (11.9%). The frequency of resistance for the MRSA were ampicillin 22 (100%), penicillin G 21(95.5%) and least was to gentamicin 2 (9.1%). The minimum inhibitory concentrations of oxacillin were greater than 128 µg /ml. CONCLUSION: The detection rate of S. aureus and MRSA strains are of great public health concern which requires continuous health education on rational use of antibiotics among others

Serological evidence of exposure to Toxoplasma gondii infection in wild birds and local chickens (Gallus gallus domesticus) in Plateau State, North Central Nigeria.

Toxoplasma gondii, the cause of toxoplasmosis is an obligate intracellular protozoan parasite of veterinary and public health importance. Ground feeding birds play an active role in the epidemiology of the disease and are the best indicators of soil contamination with the oocysts. Thirteen (14.1%; 95% CI = 7.7-23.0) of the 92 wild birds (6 of Coliformes; 4 of Columbiformes; 67 of Passeriformes and 15 of Piciformes) captured from Shere hills and 43 (9.3%; 95%CI = 4.9-12.4) of the 460 local chickens obtained across 3 senatorial regions of Plateau State, Nigeria were positive for anti-T. gondii antibodies using enzyme linked immunosorbent assay (ELISA). Varying prevalence (16.7-100%) of anti-T. gondii antibodies were recorded across 10 of 35 wild bird species; 2 (28.6) of 7 African thrush (Turdus pelios), 2 (33.3) of 6 speckled mouse bird (Colius striatus), 1 (20.0%) of 5 speckled fronted weaver (Sporopipes frontalis), 1 (33.3%) of 3 Northern Red bishop (Euplectes franciscanus), 1 (50.0%) of 2 village weaver (Ploceus cucullatus), 2 (28.6%) of 7 common bulbul (Pycnonotus barbatus), 1 (50.0%) of 2 black crowned tchagra (Tchagra senegalus), 1 (50.0%) of 2 black billed wood dove (Turtur abyssinicus), 1 (100.0%) of 1 mocking cliff chat (Thamnolaea cinamomeiventris), 1 (16.7) of 6 vieillot's barbet (Lybius vieilloti). The prevalence did not vary significantly based on the sex (p = 0.14), feeding guild (p = 0.53) and the taxonomic order (p = 0.62) of the wild birds. Regional based prevalence among local chickens ranged between 8.0 and 11.8% across the 3 senatorial zones. The source (p = 0.513; 95% CI = 4.9-16.8) and age (p = 0.797; 95% CI = 4.9-16.8) of local chickens were not associated with T. gondii seropositivity. Seropositivity was higher in the females (95% CI = 9.1-18.3) than in the males (p = 0.004; 95% CI = 3.0-9.4). This is the first report of the serological evidence of exposure to T. gondii infection in a wide variety of wild birds and local chickens in the area. It suggest that birds in this region are important asymptomatic intermediate hosts and play a role in the maintenance of the organism in the ecosystem.

Prevalence and distribution of dermatophytosis lesions on cattle in Plateau State, Nigeria.

BACKGROUND AND AIM: Dermatophytosis is an infection of the superficial, keratinized structures of the skin, nails, and hair of man and animals caused by a group of fungi called dermatophytes in the genera Trichophyton, Microsporum, and Epidermophyton. The prevalence of dermatophytosis among cattle in Nigeria and Plateau State, in particular, is yet to be fully determined. This study aimed to determine the prevalence and the distribution of dermatophytosis lesions on cattle in Plateau State, Nigeria. MATERIALS AND METHODS: Four hundred and thirty-seven cattle showing visible skin lesions suggestive of dermatophytosis were drawn from nine local government areas (three each) from the three senatorial districts of Plateau State, Nigeria. Skin scrapings were aseptically collected using a cross-sectional study, in which sampling units were selected using purposive sampling method. Samples were processed for both direct microscopic examination and isolation of dermatophytes in culture. The isolates were stained with lactophenol cotton blue and identified microscopically based on the size, shape, and arrangement of macro- and micro-conidia. The dermatophytes were further identified by determining the sequences of the internal transcribed spacer regions of their ribosomal DNA. Data were analyzed and presented as percentages, bar graph, and Chi-square test of association. p≤0.05 was considered statistically significant. RESULTS: The overall prevalence rate of bovine dermatophytosis in Plateau State was found to be 11.0%. Trichophyton verrucosum was more frequently isolated (54.2%) than Trichophyton mentagrophytes (45.8%). Age, breed, management practice, and season were significantly associated with the occurrence of the disease (p<0.05). CONCLUSION: Dermatophytosis among cattle may be of public health significance in Plateau State, Nigeria. This is the first report on the prevalence and distribution of dermatophytosis lesions on cattle from Plateau State, Nigeria.

A risk assessment study of the occurrence and distribution of aflatoxigenic Aspergillus flavus and aflatoxin B1 in dairy cattle feeds in a central northern state, Nigeria.

Nigeria, being a tropical nation, characterized by favorable climatic conditions, may display high chances of feed contaminations due to aflatoxigenic Aspergillus flavus with the consequences of health risks associated with the consumption of dairy products. A cross-sectional study was conducted to examine the risks of occurrence and distribution of aflatoxigenic Aspergillus flavus (A. flavus) and aflatoxin B1 (AFB1) contamination levels based on the European Union (EU) and United States Food and Drug Administration (USFDA) set limits. Feeds (n = 144) were collected from selected conventional and traditional dairy herds; prepared and analyzed using immuno-affinity column (IAC) and high performance liquid chromatography (HPLC) respectively. Forty eight (55.8%) isolates were identified as A. flavus of the isolated Aspergilli (n = 86). Of this proportion, 12 (25.0%) were aflatoxigenic strains. An outrageous number of the tested feeds (86.8%, n = 144) were positive for AFB1 contamination. Detectable AFB1 concentrations ranged between (0.5 and 24.8) µgKg-1 and were distributed variously according to many factors of distribution. Eighty three (66.4%, n = 125) of the AFB1 contaminated feed samples showed AFB1 concentrations between 5 and ≥20 µgKg-1. All-inclusive policies are key to reducing the health risks posed to the consumers of dairy products.

Molecular Characterization and Phylogenetic Analysis of Listeria monocytogenes Isolated from Milk and Milk Products in Kaduna, Nigeria.

In this study, Listeria (L.) monocytogenes isolated from milk and milk products in Kaduna, Nigeria, were subjected to a multiplex PCR assay to identify virulence-associated genes (such as prf A, inl A, hly A, act A, and iap). Of the 36 isolates, 9 (25%) were positive for one or two virulence-associated genes. Based on the sample type, 6 (16.9%) of the isolates that possessed virulence-associated genes were obtained from raw milk, 2 (3.2%) from "Manshanu," and 1 (2.8%) from "Kindrimo." Sequence and phylogenetic analysis based on the 16S rRNA revealed that Nigerian L. monocytogenes isolates (NGA 34A, NGA 35A, NGA 41A, and NGA 38A), when compared with reference L. monocytogenes, were grouped into two distinct clusters, A and B, with sequence (NGA 34A, NGA 35A, and NGA 41A) phylogenetically closer to J1776; N1-011A; R2-502; J1816; and J2-031, whereas L. monocytogenes isolate (NGA 38A) clustered with EDG; J1-220; J1926; J1817; and J2-1091. The separation of the Nigerian L. monocytogenes isolates into linage A (responsible for epidemic listeriosis) and lineage B (responsible for sporadic cases of listeriosis) is of public health concern and that local isolates might have potentials for human food borne listeriosis based on the virulence factors so far identified.

Public Health Implications and Risk Factors Assessment of Mycobacterium bovis Infections among Abattoir Personnel in Bauchi State, Nigeria.

Bovine tuberculosis (bTB) is a chronic infectious and contagious zoonotic disease of domestic animals, wild animals, and humans. It poses a public health threat and economic losses due to abattoir condemnation of infected carcasses during meat inspection of slaughtered animals. Bovine tuberculosis is widespread in Africa including Nigeria affecting both cattle and humans, particularly Northern Nigeria. A prospective survey was conducted from June to August 2013 in the three Zonal abattoirs of Bauchi State, Nigeria. A total of 150 structured close-ended questionnaires were administered to abattoir personnel to assess their level of awareness of bTB. This study was aimed at determining the level of public health awareness, attitude, and practices of abattoir workers of bTB in Bauchi State, Nigeria. There was a statistically significant association between respondents' awareness of bTB and their occupational status, age, and duration of exposure to cattle carcasses (P < 0.05); the odds of being aware of bTB were 9.4, 7.3, and 2.1, respectively. In conclusion, these demonstrate the urgent need for public health authorities to intervene in bTB control. The risk of bTB transmission as indicated by the personnel's practices and awareness levels in Bauchi State could be prevented through the use of protective clothing (PPEs).

Detection of Mycobacterium bovis in Organs of Slaughtered Cattle by DNA-Based Polymerase Chain Reaction and Ziehl-Neelsen Techniques in Bauchi State, Nigeria.

Bovine tuberculosis is a chronic, infectious, and contagious zoonotic disease of domestic animals, wild animals, and humans. It also poses a public health threat and economic losses. This study was aimed at determining the prevalence of bovine tuberculosis in slaughtered cattle, based on PM meat inspection, Ziehl-Neelsen staining, and PCR techniques in Bauchi State, Nigeria. A Prospective study was conducted on 800 cattle slaughtered in the three Zonal abattoirs of Bauchi State, Nigeria. One hundred and twenty (15%) tissues from different organs had suspected bTB lesions at PM. Out of the samples examined 35 (29.2%) were AFB positive by ZN and 10 (8.3%) were confirmed positive for M. bovis by PCR, with an overall prevalence of 29.16% and 8.33%, respectively. Female had a higher prevalence rate than male cattle at 16.66% and 12.5 % by ZN and 5.00% and 3.33% by PCR, respectively (P>0.05, χ (2) = 0.218). However, there was a statistically significant association (P<0.05, χ (2) = 7.002) between detection of bTB and the age of cattle. ZN revealed that cattle aged 6 years and above had the highest number of positive bTB cases 67.9%, while cattle aged 3-5 years had the lowest 14.81%. PCR technique revealed that the cattle aged 6 and above years also had the highest percentage positive M. bovis cases of 22.84%, whereas cattle aged 3-5 years had the lowest and the overall prevalence rate of 8.33%. The study found a high infection rate of bTB among cattle and majority of the lesions 54.2% were from lungs. The prevalence of bTB was higher in Bauchi metropolitan abattoir which supplies larger population of the state with beef.

Severe generalized skin lesions due to mixed infection with Sporothrix schenkii and Dermatophilus congolensis in a bull from Jos, Nigeria.

Sporothrix schenkii and Dermatophilus congolensis were isolated from a bull with severe generalized skin lesions. The lesions were thick, crusty and scabby on the dorsal part while few scabby and several nodular lesions were seen on the lower limbs especially the thighs. Scab samples and exudates from the nodules were aseptically collected and processed for bacteriology and mycology. Gram stained smears revealed Gram-positive, filamentous organism that had longitudinal and transverse septa suggestive of D. congolensis. Colonies on 5% defibrinated sheep blood agar were small, rough, grayish-white, ß-hemolytic and adherent to the medium. It was catalase positive, urease positive and fermented glucose and maltose but not sucrose, lactose, mannitol, sorbitol and xylose. Colonies on Sabouraud's dextrose agar were small, round, white and opaque, delicate and smooth. It liquefied gelatin and fermented glucose and sucrose but not galactose, menite, and glycerin. The isolate was Gram-positive, cigar-shaped and yeast-like suggestive of S. schenkii. Dermatophilosis is common in domesticated ruminants while sporotrichosis is very rare in cattle. This may be the first report of bovine sporotrichosis from Africa.

'Prevalence and antimicrobial susceptibility of Listeria monocytogenes and methicillin-resistant Staphylococcus aureus strains from raw meat and meat products in Zaria, Nigeria.

UNLABELLED: The bacterial genera Listeria and Staphylococcus have been frequently isolated from food products and are responsible for a number of animal and human diseases. The aim of the study was to simultaneously isolate and characterize L. monocytogenes and Staphylococcus species from 300 samples of raw meat and meat products, to determine the susceptibility of the organisms to commonly used antimicrobial agents and to determine the presence of haemolysin A (hyl) virulence gene in L. monocytogenes and staphylococcal cassette chromosome mecA (SCCmec) gene in the Staph. aureus isolates using PCR. Of the 85 Listeria isolates tested, 12 L. monocytogenes were identified and tested for their sensitivity to 14 antimicrobial agents. All the 12 isolates (100%) were resistant to nine antimicrobial agents, but however sensitive to gentamicin. Only one isolate was found to harbour the hylA gene. Twenty-nine isolates were confirmed as Staph. aureus by the Microbact 12S identification system and were all presumptively identified as methicillin-resistant Staph. aureus species using oxacillin-resistant Staph. aureus basal medium (ORSAB). The 29 Staph. aureus isolates were tested for their sensitivity to 16 antimicrobial agents, and 11 were resistant to methicillin. None of the 11 Staph. aureus isolates harboured the methicillin resistance, mecA gene. SIGNIFICANCE AND IMPACT OF THE STUDY: Listeria monocytogenes and Staphylococcus aureus are important agents of foodborne diseases. Occurrence of these infectious agents was established in meat and meat products in Zaria, Nigeria. Majority of isolates obtained from this study, displayed multidrug resistance to commonly used antimicrobial agents, including methicillin resistance among the Staph. aureus isolates. The potential virulence of L. monocytogenes found in ready-to-eat food was documented by the carriage of hly A gene by one of the isolates. A different mechanism of methicillin resistance or different homologue of mec A gene may be circulating among Nigerian isolates.

Assessment of carcass contamination with E. coli O157 before and after washing with water at abattoirs in Nigeria.

The study was carried out to assess the level of beef carcass contamination with Escherichia coli including O157 strains before and after washing with water. Samples of water used for washing carcasses were collected and thirty beef carcasses were swabbed within a period of one month in each of three abattoirs located in North-Western states of Nigeria. E. coli were enumerated as indicator organisms. Using conventional biochemical tests, the isolation rate of E. coli in the 120 swab samples collected in each abattoir from external and internal surfaces of the carcasses was 58.3% at Kano abattoir, 70.8% at Sokoto abattoir, while 76.7% was recorded at Zango abattoir. E. coli counts from external and internal surfaces of the carcasses were enumerated as mean log and ranged between 4.3 Log(10) and 4.6 Log(10) cfu/cm(2) before washing, while the values were 4.6 Log(10) and 4.9 Log(10) cfu/cm(2) after washing. Data analysis revealed that the increase in E. coli counts after washing carcasses with water was statistically significant (P<0.05) in all the abattoirs. However, there was no statistically significant difference (P>0.05) between the 3 abattoirs in mean log of E. coli counts from external surfaces of carcass after washing. E. coli O157 was identified from both the water and surfaces of carcasses using Latex agglutination kit. A prevalence of 2.8% of E. coli O157 was detected in 360 swab samples from 90 beef carcasses examined. E. coli counts from water used in washing carcasses were between 22 and 120 cfu/100 ml. Of the 72 water samples, 3(4.2%) were positive for E. coli O157. In conclusion, there was increased contamination of carcasses during processing and water used in washing carcasses might have contributed to carcass contamination in all the abattoirs studied due to use of non-potable water.

Enteropathogenicity of Bacillus cereus isolated from some Nigerian foods.

BACKGROUND: Bacillus cereus is a soil bacterium and has been isolated from cooked and uncooked rice, milk and dairy products, meat, spices, garlic, vegetables, cereals and infant formulae. OBJECTIVE: To report on the enteropathogenicity of B. cereus isolated from Nigerian foods. METHODS: Forty-five Bacillus cereus isolates classified as diarrhoeal and emetic strains were assayed for enterotoxin production. Thirty extractions were from diarrhoeal strains and 15 from emetic strains. RESULTS: Forty-five Bacillus cereus isolates classified as diarrhoeal and emetic strains were assayed for enterotoxin production. Of the 30 toxin extractions from B. cereus classified as diarrhoeal strains, 18 (60%) gave positive ileal-loop reactions, while 15 toxin extractions from emetic strains of B. cereus gave negative ileal-loop reactions. CONCLUSION: The work has demonstrated the distribution and toxigenicity of B. cereus in various Nigerian foods. An appreciable number of Nigerian food isolates are capable of causing diarrhoea. Forty percent of the enterotoxigenic isolate were mild to severe enterotixin producers, with 31% mild, 6.7% moderate and 2.2% severe.

Electropherotypes and subgroups of group A rotaviruses circulating among diarrhoeic children in Kano, Nigeria.

BACKGROUND: It is estimated that about 600,000 children die annually as a result of severe dehydrating diarrhea caused by rotaviruses. The virus is a double stranded RNA (dsRNA) virus with 11 segments. Group A rotaviruses show a characteristic 4-2-3-2 pattern following electrophoresis. The VP6 subgroups, I and II exist. This work was carried out to study the prevalence of rotavirus infection among children 0-5 years with diarrhea in Kano, and to determine the circulating subgroups and electropherotypes and of the rotavirus isolates. METHODS: Two hundred and eighteen stool specimens from children 0-60 months (198 diarrheic and 20 non-diarrheic) were collected from different hospitals and health care centers in Kano and subjected to group A rotavirus enzyme linked immunosorbent assay (ELISA) to determine presence of group A rotavirus, subgroup ELISA to determine the VP6 subgroups and polyacrylamide gel electrophoresis (PAGE) to determine the electropherotypes present. RESULTS: The long electropherotypes (47.05%) of four variations dominated over the short electropherotype (17.64%). About 11.76% of the isolates were of mixed infection. Dominance of subgroup II (45%) over subgroup I (25%), and the presence of both subgroups I and II (10%) and neither subgroup I nor II (15%) was observed in this study. CONCLUSION: Information on the genomic diversity of the RNA electropherotypes in this region, Kano, is reported in this study.

Electropherotypes and Subgroups of Group A Rotaviruses Circulating among Diarrhoeic Children in Kano; Nigeria

Background: It is estimated that about 600?000 children die annually as a result of severe dehydrating diarrhea caused by rotaviruses. The virus is a double stranded RNA (dsRNA) virus with 11 segments. Group A rotaviruses show a characteristic 4-2-3-2 pattern following electrophoresis. The VP6 subgroups; I and II exist. This work was carried out to study the prevalence of rotavirus infection among children 0-5 years with diarrhea in Kano; and to determine the circulating subgroups and electropherotypes and of the rotavirus isolates. Methods: Two hundred and eighteen stool specimens from children 0-60 months (198 diarrheic and 20 non-diarrheic) were collected from different hospitals and health care centers in Kano and subjected to group A rotavirus enzyme linked immunosorbent assay (ELISA) to determine presence of group A rotavirus; subgroup ELISA to determine the VP6 subgroups and polyacrylamide gel electrophoresis (PAGE) to determine the electropherotypes present. Results: The long electropherotypes (47.05) of four variations dominated over the short electropherotype (17.64). About 11.76of the isolates were of mixed infection. Dominance of subgroup II (45) over subgroup I (25); and the presence of both subgroups I and II (10) and neither subgroup I nor II (15) was observed in this study. Conclusion: Information on the genomic diversity of the RNA electropherotypes in this region; Kano; is reported in this study

Abortion due to Brucella abortus in sheep in Nigeria.

This paper reports on a sporadic, naturally acquired infection of sheep with Brucella abortus on a privately owned farm in Toro near Bauchi, Nigeria. The abortions, which occurred in a flock of 28 Yankassa sheep, involved five ewes at the third month of gestation. Serum and milk samples from the flock were examined for Brucella antibodies by the Rose Bengal plate test, serum agglutination test (SAT) and milk ring test (MRT). The proportion shown as positive by SAT was 14.3%. All the five milk samples examined by MRT were positive. A total of seven isolates of Brucella were obtained from three milk samples and four vaginal swabs collected from aborting ewes. All isolates were identified and biotyped as B. abortus biovar 1. This biovar was also isolated from cattle maintained on the farm in association with the sheep. The infection was attributed to the animal husbandry practices employed on the farm.

Phenotypic characterization of Brucella strains isolated from livestock in Nigeria.

Isolation of brucellae from aborted fetuses, hygroma fluids, milk and vaginal swabs obtained from aborting cattle, sheep, goats, pigs, and horses in Nigeria was carried out. A total of 25 isolates, obtained mainly from cattle, sheep and horses, were biotyped. All strains belonged to one species, Brucella abortus biovar 1. The epidemiological significance of this finding is discussed. Some preliminary observations on the zoonotic and public health implications of Brucella infection in Nigerian livestock are presented. A control programme involving improved management, animal movement restrictions, public health education and mass vaccination of animals is suggested.

Epidemiology of astrovirus infection in Zaria, Nigeria.

Astrovirus has been shown to be an important aetiological agent associated with gastroenteritis in children, although few studies have been conducted in Africa. In this study, stool specimens were obtained from 375 young children less than 5 years of age with acute gastroenteritis presenting at Ahmadu Bello University Hospital, and from a control group of 122 children without diarrhoeal illness. The specimens were examined for the presence of human astroviruses using a monoclonal antibody-based ELISA (Astrovirus IDEIATM, Dako, UK). Negative staining electron microscopy was performed on specimens to confirm the presence of astrovirus particles. Astrovirus was detected in 6.7 per cent (25/375) of the diarrhoeal stools compared to 5.7 per cent (7/122) of the control specimens. Astrovirus seemed to infect older children and more than half the children were between 1 and 4 years of age (15/25). Only four children were less than 6 months old. A winter peak of shedding was observed.

Escherichia coli cellulitis in broiler chickens: clonal relationships among strains and analysis of virulence-associated factors of isolates from diseased birds.

Thirty-nine Escherichia coli isolates from broiler chickens with cellulitis were serotyped and analyzed for clonal relationships by multilocus enzyme electrophoresis. The isolates were further characterized with respect to hemagglutination (HA); serum resistance; antibiotic susceptibility; production of aerobactin, colicin V, and hemolysin; expression of K1 or K5 capsule; sensitivity to cloacin DF13 after treatment with diphenylamine; expression of iron-regulated outer membrane proteins; and virulence in 1-day-old chickens. In addition, the isolates were examined for the presence of DNA sequences related to F1A (fim) and P (pap) fimbriae, aerobactin synthesis (iuc) and transport (iut), hemolysin operon hly, and TraT lipoprotein-induced serum resistance (traT). Only 38.4% of the isolates were typeable with standard O antisera, and of these, serogroups O25 and O78 were the most frequently observed. Multilocus enzyme electrophoresis, based on 20 enzymes, resolved 17 electrophoretic types, forming seven clusters. Isolates from four of these clusters fell into E. coli clone complexes that have been previously reported to be commonly associated with avian colibacillosis. All isolates expressed two to five iron-regulated outer membrane proteins, were resistant to serum and cloacin DF13, and possessed DNA sequences homologous to fim and iuc/iut. Most isolates (72%) were positive for traT, and a majority produced colicin V and aerobactin (92 and 82%, respectively). Assays for the presence of fim and pap DNA sequences, for HA, and for virulence gave variable results but suggest that cellulitis isolates may express F1A and/or other mannose-resistant HA fimbriae different from P and may be virulent in 1-day-old chickens. Our results support the hypothesis that cellulitis in broilers in many cases is caused by E. coli clones identical to other pathogenic avian E. coli strains. Certain clones may be specific to cellulitis, because 25% of the isolates tested belong to clusters not related to known clone complexes.

A carAB mutant of avian pathogenic Escherichia coli serogroup O2 is attenuated and effective as a live oral vaccine against colibacillosis in turkeys.

Colibacillosis is a serious and economically important disease of the respiratory tract of chickens and turkeys. The serogroups of Escherichia coli commonly associated with colibacillosis in poultry are O1, O2, and O78. Although previous attempts to develop a vaccine have not been very successful, vaccination is still considered the most effective way of controlling the disease. Therefore, our laboratory has been involved in the development of an attenuated live vaccine that will be effective in the prevention of colibacillosis. The carAB operon coding for carbamoyl-phosphate synthetase, an essential enzyme in arginine and pyrimidine metabolism, was selected for study. Generalized transduction was used to transfer a Tn10-generated mutation from a laboratory strain to virulent avian field isolates of E. coli. Molecular techniques were used to determine the point of Tn10 insertion within the carAB operon. The insertion mutants were then cured of the tetracycline resistance gene of the transposon to select for antibiotic-sensitive and stable carAB mutants. The degree of attenuation obtained by the mutation was determined in day-old chickens. Typically, when 100-fold the 50% lethal dose (for the wild type) was given, no more than 50% mortality in the day-old chickens was observed. The deletion mutant of serotype O2 was also found to be avirulent in turkeys rendered susceptible to infection with hemorrhagic enteritis virus A. Turkey poults vaccinated orally at 4 weeks old with either the wild-type E. coli EC317 strain or its carAB mutant EC751 were completely protected from infection following challenge with the homologous wild-type strain. Our data indicate that carAB mutants of virulent avian strains of E. coli will be effective and safe as live oral vaccines for prevention of colibacillosis in poultry.