Bacterial and rota viral causes of diarrhoea in children under 5 years and the genetic basis of antibiotic resistance
Ndung’u, Perpetual Wangui
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Diarrhoea causes significant morbidity and mortality among children in Kenya. The Illness is caused by a variety of pathogenic organisms, some which are difficult to identify immediately. This results in the use of enormous amounts of antibiotics and as a result, some of the pathogens develop resistance. This study was carried out between June 2003 and January 2004 to investigate the main causes of diarrhoea in children below the age of five years. It also sought to evaluate the problem of antibiotic resistance among these isolates, the role of plasm ids in the resistance and how much of this resistance was transferable. A total of 402 sample stool samples were collected from Kenyatta National Hospital, examined macroscopically to determine the presence of blood, pus, or mucus \\ luch are an important lead in determining the causative agents. The specimens were cultured in general and specific media to isolate different bacteria. Biochemical tests were carried out on suspect colonies for proper identification followed by API 20E screening test. A total of 13 different genera of bacteria were isolated some of which were non-pathogenic. The three genera of pathogenic bacteria isolated including 389 /:".co/i, I 1 Salmonella spp., and 5 ,\'!7iy;,-,IIa spp. Two viral species, 8 rota vi ruses and 2 corona viruses, were isolated from the first 100 specimens. Antibiotic sensitivity tests [vcete carried out on the pathogenic isolates using the Kirby Bauer disc diffu ion method. ".".coli ATCC 25922 was used as control to test the potency of the antibiotics. A total of 12 commonly used antibiotics for treatment of Gram-negative bacteria were used for the sensitivity tests. Plasmid fingerprinting was carried out using Horizontal Agarose Gel Electrophoresis (HEG) on the Ii.coli isolates. In vitro conjugation experiments were also undertaken to determine possible transfer of resistance to Ecoli K 12 F- Na" that has no plasm ids. Results from sensitivity tests indicated multidrug resistance on all three pathogenic strains. The highest resistance was shown by E coli, where four isolates were resistant to II of the 12 antibiotics used. The order of resistance by E.coli was highest on Trill1ethoprim-sulphamethaxazole (89%), and lowest on ceftazidime (4.6%). Salmonella and Shigella showed similar resistance, with highest resistance shown on Trimethoprimsulphamethcprirn (906%), while nalidixic acid, ciprofloxacin and gentamicin were effective on all the isolates of bacterial pathogens isolated. In addition,· all Shigella isolates were sensitive to ceftazidime. The drug resistant Ecoli had plasmids ranging between 2.0 and 98 megadaltons (Mda). Conjugation experiments showed that the ability to transfer resistance phenotypes by the larger plasmids existed for ampicillin, ch loramphenicol and tetracycline. The presence of ciprofloxacin resistant E.coli raises serious concerns and hence need for its frequent monitoring. These results indicate that there is need for constant surveillance on all antibiotics used for treatment of diarrhoea in children and to sensitize the public on the proper use of antibiotics.