CLINICAL MANIFESTATIONS IN RABBITS EXPERIMENTALLY INFECTED WITH ESCHERICHIA COLI O157:H7 ISOLATES OF DIFFERENT VIRULENCE GENE PROFILES

Escherichia coli O157:H7 is a major cause of zoonotic food-borne infections transmissible from asymptomatic animals to humans following consumption of contaminated foods. Pathogenicity of E. coli O157:H7 is attributed to possession of virulence genes such as eaeA and stx responsible for intimate adhesion to enterocytes and production of cytolethal shiga toxins. The pathogenic potentials of five E. coli O157:H7 isolates of different virulence gene profiles recovered from the faeces of slaughter cattle was compared in rabbit model. Five groups (A-E) of five rabbits were each inoculated orally with 5 x 109 colony forming units of an E. coli O157:H7 isolate possessing one of the virulence gene profiles: stx1 / stx2 / eaeA / hlyA (group A), stx1 /stx2 (B), stx1 (C), stx2 (D), and eaeA / hlyA (E). Group F (control) received sterile broth. The mean onset and duration of clinical manifestations varied significantly among the experimental groups being earliest and shortest in group infected with E. coli O157:H7 possessing stx1 / stx2 /eaeA / hlyA. Infected rabbits showed clinical signs including dullness, profuse non-bloody diarrhoea, weakness, anorexia and epistaxis starting from two days post infection (p.i.). Epistaxis was observed only in rabbits inoculated with isolates that possessed stx2 either alone or in combination with other virulence genes. Mortality of 100% was recorded in isolates with stx1 /stx2 /eaeA / hlyA, stx1 / stx2 and stx2­ and 60% with stx1 and eaeA / hlyA.  Test organisms were detected in the faeces of inoculated animals as from two days p.i. and persisted in survivors for 19 to 30 days p.i. This study showed that E. coli O157:H7 isolates from cattle produced fatal illness in experimental rabbits and that virulence gene profile significantly influenced the onset, duration and severity of clinical manifestation of infection in the experimental animals.     &nbsp

<em>In Vitro</em> Antimicrobial Susceptibility Testing of Animal <em>Nocardia</em> Isolated from Field Cases of Skin Diseases

In vitro antimicrobial tests were carried out on strains of Nocardia isolated from field cases of cutaneous nocardiosis in farm animals. Results with the disc diffusion test showed the multiresistant nature of the isolates, but 23.81 and 21.43% were sensitive to ciprofloxacin and gentamycin, respectively. The MIC mode and range for oxytetracycline were 12.5 and 3.12–25 μg/ml, respectively, while those of erythromycin were 3.12 and 0.78–6.25 μg/ml, respectively

Bovine Streptococcal Mastitis in Southwest and Northern States of Nigeria

An investigation was carried out to identify the streptococci species isolated from clinical cases of bovine mastitis in Kwara, Kaduna and Oyo States of Nigeria. Milk samples from 200 clinically mastitic udders were bacteriological studied. A total of 130 streptococci isolate belonging to six species of streptococci, namely S. uberis , S. agalactiae , S. dysgalactiae , S. epidemicus , S. bovis , S. equinus were recovered from the milk examined. Streptococcus uberis was the most frequently encountered species with an incidence of (55.4%) followed by Streptococcus agalactiae (24.6%), Streptococcus dysgalactiae (12.3%) Streptococcus zoopidemicus (3.9%) Streptococcus bovis (2.3%) and Streptococcus equinus (1.5%). These species of streptococcus are of great public importance

Immunogenicity and Pathology of Formalin-Killed-Sepa Salmonella Enterica Paratyphi A Antigen in Pullet

Intensive poultry production in Nigeria is currently on the increase with associated health challenges. This work investigated the immunogenicity of a documented Salmonella enterica Paratyphi A (SEPA) of poultry. A formalin-killed-SEPA containing 1x107cfu/ml was used as antigen. Seventy-five pullets were immunized orally with the antigen at 4 weeks of age and another 25 pullets (UC) served as unimmunized control. First and second booster doses were given at 10th and 29th day post-immunization (p.i). Three groups of immunized pullets (IA, IB, and IC) each of the 25 pullets were challenged with 0.5ml broth containing: &gt;1x108cfu/ml SEPA (IA), 1x108cfu/ml Salmonella Gallinarum-(SG) (IB), while the immunized control group (IC) was fed with sterile broth. The unimmunized control group (UC) was infected with 1x108cfu /ml Salmonella enterica Paratyphi A. The formalin-killed vaccine of SEPA was immunogenic in poultry as indicated by the presence of O and H antibodies in the sera of pullets, producing protection only in pullets challenged with homologous strain, whereas morbidities and mortalities were recorded in unimmunized UC pullets challenged with homologous SEPA strain and IB challenged with heterologous strain (SG) during a 21-day experimentation. Also the inactivated-SEPA vaccine was able to protect birds against homologous challenge. These findings show that the inactivated-SEPA as a potential candidate vaccine offers protection of pullets against the emerging SEPA infection in pullets to avert severe economic losses in growing poultry industry and make the much needed animal protein available to feed the nation’s population.Keywords: Salmonella enterica Paratyphi A, immunogenicity, vaccine, poultry

Pathogenicity of <em>Salmonella</em> Paratyphi A in Pullets

The pathogenicity of Salmonella Paratyphi A isolated at Debiwise Poultry Farm during a fulminating outbreak was tested. Twenty 16-week-old pullets were inoculated orally with 0.5 ml of 1.3 x 108 CFU/bird Salmonella Paratyphi A, while 20 others of the same age served as uninfected control. By the fourth day postinoculation (p.i.) dullness, ruffled and unkempt feathers, somnolence, yellowish- green diarrhea, decreased water and feed consumption were observed in the infected birds; mortality was 95% by day 16 p.i. Remarkable pathological lesions were recorded between days 7 and 14 p.i. The liver was moderately enlarged, with multiple necrotic foci, and dark brown to bronze coloration. The kidneys were swollen, with widespread focal pale necrotic areas, while the spleen was slightly enlarged. Histopathologically, the proventriculus showed focal glandular necrosis, mononuclear cell infiltration and moderate perivascular leucocytic infiltration. There was mucosal hemorrhage, matting of intestinal villi with reduction of villous height and presence of epithelial debris in the lumen with increased leucocytic infiltration in the lamina propriae. The liver showed moderate, diffuse congestion of the sinusoid and central veins, as well as multiple foci of necrosis of hepatocytes, mononuclear infiltration and perivascular cellular infiltration. There was diffuse lymphoid depletion in the nodule and around the splenic arterioles as well as throughout the parenchyma. The kidneys were congested with tubular epithelial necrosis characterized by karyorrhexis of the nuclei. The organism was recovered from the liver, spleen, heart, heart blood and bone marrow of infected birds. No clinical sign or gross lesion or pathogen was observed in the negative control

Occurrence of Methicilin-resistant Staphylococcus aureus in a Nigerian tertiary Hospital

A total of 3,692 clinical samples consisting 1,969 urine samples, 535 blood culture, 362 high vagina swabs, 207 endocervical swabs, 125 cerebrospinal fluid, 136 ear swabs, 200 eye swabs and 158 wound swabs were microbiologically investigated for Staphylococcus aureus and methicillin resistant Staphylococcus aureus at the Department of Medical Microbiology, University Teaching Hospital Ibadan. Two hundred and eight Staphylococcus aureus (5.6%) were isolated, twenty two, (10.6%) of which were methicilin resistant. Nine isolates 9/22(40.9%), were resistant to nine antibiotics having, R-type aug.amg.amx.pef.tet.cxc.e.nit.nal, two isolates 2/22 (9.1%) had octuple resistant pattern ; R-type aug.amg.amx.pef.cxc.e.nit.nal, four isolates 4/22 (18.2%) had septuple ; R-type aug.amg.amx.pef.cxc.e.nit resistant pattern, two isolates 2/22(9.1%) had quintuple ; R-type aug.amx.cxc.e.nit, one isolate 1/22 (4.5%) quadruple ; R-type aug.amx.cxc.nit, and another four isolates 4/22 (18.2%) had triple; R-type amx.cxc.nit. Seventeen, (77.3%) of the methicilin resistant Staphylococcus aureus, were resistant to 30mcg Ceftriaxone, while nineteen, (86.4%) were resistant to 30mcg Ceftazidime. All the twenty two methicilin resistant Staphylococcus aureus were resistant to Amoxycillin (25mcg), Cloxacillin (10mcg), Nitrofurantoin (300mcg), and Gentamycin (10mcg). The MIC of Ceftazidime for 3 isolates, 3/19(15.8%) was 120mcg/ml and the MIC of Ceftazidime for 16 isolates, 16/19 (84.2%) was 60mcg/ml, while the MIC of Ceftriaxone for 1 isolate, 1/17 (5.9%), 6 isolates, 6/17 (35.3%) , 10 isolates, 10/17 (58.8%) were >150mcg/ml, 150mcg/ml, 75mcg/ml respectively and the MIC of Ceftriaxone for the remaining 6 isolates, 6/17(35.3%) was 37.5mcg/ml . Taking into consideration the danger associated with methicillin resistant Staphylococcus aureus, the findings from this study underscores the need for public enlightenment of both the hospital workers and the general public on the risk associated with this group of globally important pathogens and the necessary precautions for its control both in the hospitals and the communities in Nigeria