Isolation of Bacterial pathogens from dead- in- shell Chicken embryos from local Hatcheries

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Swithine, Hameenda Kabilika
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Commercial hatcheries in Zambia have been experiencing losses due to dead-in-shell embryos for quite sometime. Numerous Salmonella serotypes have been frequently recorded in poultry population in Zambia, but no information is available on bacterial association with dead-in-shell mortality in hatcheries. Hence investigation into three commercial hatcheries of Zambia was made to find out the role of bacterial pathogens in embryonic mortality and hatchability. These hatcheries had an average dead -in-shell losses between 15.2% and 31.1%. One thousand dead-in-shell chicken embryos from each hatchery formed samples. Ten pooled yolk sac contents or whole egg contents formed one sample. The homogenised samples were cultured on suitable media. Isolation and identification of bacteria was done according to standard bacteriological methods. Three hundred and eighty three (383) cultures were isolated. More than half (208) were isolated firom hatchery A, the other two hatcheries B and C had 118 and 57 cultures isolated respectively. Majority of the isolates were enteric group of bacteria. Out of all the isolates Escherichia coli was predominant with 18.28% (70) followed by Staphylococcus species 14.10% (54) and Pseudomonas species 11.75% (45/ Klebsiella species recorded 9.40% (36). Salmonella species, Enterobacter and Citrobacter species recorded 8.87% (34) each. Acinetobacter recorded 6.79% (26), Proteus species had 6.26% (24), Enterococcus species recorded 2.87% (11) and Streptococcus sp. had 1.04% (4). Alcaligenes faecalis and Aeromonas hydrophila both recorded 0.78% (3). Neisseria dentrificans recorded 0.52% (2) and Edwardsiella species., Micrococcus and Providencia recorded 0.26% (1) each. Out of the fifty four (54) Staphylococcus species, forty three (43)were Staphylococcus aureus. Serotyping of Escherichia coli revealed that six (6) cultures were serotype 08:k47, five (5) were serotype 09:k28, two (2) belonged to serotype 032/33:k- and one (1) each were serotype 088:k-, 016:k- and 0101 :k-. Out of seventy cultures of Escherichia coli isolated, fifty four (54) were rough untypable. All these cultures were found to be less or more pathogenic to thirteen (13) day old chicken embryos and white mice. It was also interesting to note that all of the thirty four (34) Salmonella cultures isolated were Salmonella enteritidis. However on phage typing twenty (20) belonged to phage type 4 (PT4), four (4) were phage type 1 (PTl), two (2) were phage type lb (PTlb) and another two (2) were phage type 7(PT7). One was phage type 7a (PT7a) and five were not typed. The isolation of Salmonella enteritidis, especially most invasive phage type 4, in breeding flocks for the first time in Zambia may open a new page in the epidemiology of Salmonella and a need for effective control measures in this country. A few cultures of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus were subjected to antimicrobial senshivity. The results of the antimicrobial sensitivity test showed high levels of antimicrobial resistance. Antimicrobial agents used in the test were Penicillin G, Tetracycline, Gentamycin, Sulphamethoxazole, Furazolidone and Streptomycin. The results showed that Escherichia coli serotypes were resistant to most Antibiotics (52.7%). Most cultures were resistant to Penicillin G followed by Streptomycin and Furazolidone. Antibiotics in Zambia have been used in feeds (especially nitrofurans) as a prophylactic measure to diseases like Salmonellosis and to boost production. The enforcement of legislature regulating the use of antibiotics hasn't been effectively done. This may partly explain the high levels of antimicrobial resistance observed in this limited study. The presence of these highly pathogenic bacteria in dead-in-shell associates them with production losses and are an indication of hatchery hygiene. The significance of these isolates in causing embryonic mortality and lower hatchability is discussed. There was significant correlation between dead-in-shell and hatchability. However direct relationship between bacterial prevalence or contamination and hatchability could not easily be shown. The probable reasons are discussed in this present dissertation.
Embryology -- Birds , Bacteriology