TYPING OF SALMONELLA STRAINS ISOLATED FROM WATER AND DIARRHOEIC STOOLS OF CHILDREN UNDER FIVE YEARS IN PARTS OF NORTHWESTERN NIGERIA
TYPING OF SALMONELLA STRAINS ISOLATED FROM WATER AND DIARRHOEIC STOOLS OF CHILDREN UNDER FIVE YEARS IN PARTS OF NORTHWESTERN NIGERIA
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Date
2016-06
Authors
MZUNGU, Ignatius
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Abstract
Salmonella species are important cause of gastroenteritis and are responsible for a huge global burden of morbidity and mortality. To evaluate the strains of Salmonella involved in diarrhoea among children in Northwestern Nigeria, a total of 634 diarrhoea stool samples of children aged five years and below were collected from three randomly selected states within the region and investigated for Salmonella infection. Isolates were screened for antibiotic susceptibility by disk diffusion, resistance genes by PCR and sequence analysis of 16S ribosomal RNA for strain determination. The overall prevalence of Salmonella species within the study area was 4.1%. The highest frequency of infection occurred among children aged 25-36 months (10.4%). A higher prevalence (6.5%) was observed among children from households that used mainly well water. Bacteriological quality of drinking water in the study area revealed that wells had the highest number of total coliform and faecal coliform counts, and boreholes had the lowest. Two (2.22%) well water samples were positive for Salmonella species. Varying degrees of contamination with total coliform and faecal coliform in excess of the maximum allowable limit was observed in all categories of water samples. The Salmonella isolates showed 100% resistance to Ampicilin and Amoxycillin, while 87.5% were susceptible to Ciprofloxacin. Multiple antibiotic resistance observed among isolates ranged from 3 to 9 antibiotics. Of the 23 MDR phenotypes, screened for resistance genes, 10(43.5%) were found to harbour blaTEM1 gene, 7(30.4%) were carrying cat1b gene and 2(8.7%) had aadA2 gene. Sequence analysis of the 16S rRNA obtained from the isolates showed that of the 18 isolates sequenced, 11 were affiliated to Salmonella enterica subspecies enterica serovar Typhi strain CT18, while 7 were affiliated to Salmonella enterica subspecies enterica serovar Typhimurium strain LT2. The percentage identity for all the 16S rRNA sequences ranged between 86 - 99%, with E-values of zero in all the isolates except one. Phylogenetic analysis demonstrated a common ancestry of the isolates and close genetic relatedness. Salmonella still remains one of the major and most important bacterial pathogen of diarrhoea among children in the study area. Provision of adequate potable water to the community, improving sanitary awareness through basic health education, careful surveillance and monitoring incidence and spread of diarrhoeal diseases, may help reduce the disease burden in children.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY IN MICROBIOLOGY DEPARTMENT OF MICROBIOLOGY,
FACULTY OF SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA,NIGERIA
Keywords
TYPING,, SALMONELLA,, STRAINS,, WATER,, DIARRHOEIC STOOLS,, CHILDREN,, NORTHWESTERN,, NIGERIA