A new approach to hatchery sanitation: isolation and control of pathogenic bacteria associated with deaths in hatching chicks

Abstract

Investigations have revealed Large microbial populations in many hatcheries despite the application of various sanitary measures.Many of the pathogenic organisms which affect the eggs, embryos and hatched chicks may be air-borne, egg-borne or may be from residual hatcher contamination. The degree of contamination has been measured by microbial examination of hatcher fluff, air sampling techniques, and by surface sampling; a systematic approach to hatchery sanitation depends on the elucidation of the principal sources of hatcher contamination. This study was aimed at isolating and identifying the types of pathogenic bacteria that cause mortality in hatching chicks, and determining their sources of reservoirs within hatcheries with a view to controlling them. The best samples were obtained from three hatcheries in Kenya, and from numerous poultry farms in and around Nairobi. The samples included eggs, dead-in-shells, sick and dying chicks, water, fluff, hatcher debris, and swabs from hatchery surfaces and hands of hatchery personnel. All samples were initially processed to produce appropriate inocula and cultured on MacConkey agar, Blood agar and Nutrient agar media for primary isolation. Fluids were inoculated directly onto culture media. Bacterial isolates were later inoculated onto characterisation media and biochemical preparations for identification. Purified bacterial isolates were subsequently preserved and later subjected to antibiolic and disinfectant susceptibility tests. Swabbing for total bacterial counts was made before and after application of fumigants and disinfectants to determine the sanitary status of the hatcheries. A total of 567 bacterial isolates covering over 18 genera and over 43 species was made. Of these, 237 isolates were recovered from hatchery machines and fluff and hatcher debris samples, 174 were from hatchery environment including water, air and hands of personnel, and 156 isolates were recovered from dead-in-shalls and from sick and dying chicks. The top ten most frequently isolated genera were bacillus(18.5%), Staphylococcus (17.5%),Pseudomonas(14.5%),Streptococcus (13.2%),escherichia(12.3%),Proteus(4.6%),Diploccus (4.2%), enterobacter(3.7%),Citrobacter(2.6%) and Klebsiella (1.9%). Of these, the top ten isolated from dying chicks and unhatched/incubating eggs were, in decreasing order, escherichia,Streptococcus,Staphylococcus,Proteus,Pseudomonas,bacillus, Klebsiella,enterobacter,Citrobacter and pastereulla. Two hundred and forty three of the isolates were tested against 7 disinfectants commonly used in Kenya. At the manufacturers' use-dilution, the percent kill was 97 for Bromosept(R), 60 for Lysol(R), 47 for Pynol-S(R), 40 for Rhino(R) disinfectant, 31 for Biodan(R), 7 for Kerol(R) and 0 (zero) for Municipal fluid(R)-. Whereas the Bromosept(R), Biodan(R) and Lysol(R) had broad spectrum activity,Pynol-5(R) ,Kerol(R) and Rhino(R) -disinfectants had effect mainly on G+ve bacteria only. Two hundred and sixty five of the isolates were tested against 13 antibiotics. Multiple antibiotic resistance was demonstrated mainly among members of escherichia,Streptococcus,Pseudomonas,Proteus,Citrobacter,Staphylococcus and Klebsiella in a decreasing order. The multiple resistance pattern was 25% to 3 antibiotics,19%to 4, 26% to 5, 15% to 6, 6% to 7 and 9% to 8 and over antibiotics. The top seven showing the most broad spectrum of activity were, in decreasing percentage, Kanamycin (100), Gentamicin (96), Cotrimoxazole (85), Nitrofurantoin (85), Ampicillin (82), Tetracycline (80) and Chloramphenicol (78%). Also demonstrated was existence of resistance to both antibiotics and disinfectants among many bacterial isolates, the top 7 of which were echerichia(71%), Citrobacter(64%), Proteus(60%),Klebsiella(60%),Pseudomonas(50%), enterobacter(14%) and Streptococcus(14%). The conclusions reached were that swabbing recovered a very small percentage of the bacteria on the surfaces, and that applications of fumigants and disinfectants on surfaces always left behind some bacteria resistant to these agents. The most frequent bacteria isolated from chicles and egs, e. coli. was also the one showing the highest pattern of multiple resistance to both antibiotics and disinfectants. The disinfectants tested were not effective for general purpose disinfection at the manufacturers' use - dilution except Lysol(R) and Bromosept(R). In-the-field tests for disinfectant efficacy should be carried out in a manner similar to the more routine in vitro antibiotic sensitivity tests before a choice of agent for general purpose disinfection is made.