on Brilliant Green Sulfa Agar plates. Twenty-five grams of each animal feed sample were cultured in 250 ml of Selenite Broth and incubated at. 37 °C for 18-24 ...
Bulletin of the World Health Organization, 60 (5): 803-807 (1982)
Salmonella species and serotypes isolated from farm animals, animal feed, sewage, and sludge in Saudi Arabia* N. H.
NABBUT,' E. K. BARBOUR,2 & H.
M. AL-NAKHLI3
A total of 264 salmonellae representing 65 different species and serotypes were isolated for the first time in Saudi Arabia, from various animal species, animal feed, sewage, and sludge. The six most frequently isolated Salmonella species or serotypes were: livingstone, concord, "S. schottmuelleri" (invalid), lille, S. typhimurium, and cerro.
Nearly 2000 Salmonella serotypes have already been described and all are considered to be potentially pathogenic for man or animals or both; they differ in their host adaptations, the pathological syndrome produced, and geographical distribution. The presence of salmonellae in livestock and poultry and in environmental sources not only causes economic losses in these animals but also constitutes a potential hazard to human health. The isolations of salmonellae from farm animals, animal feed, sewage, and sludge in Saudi Arabia during 1977-80 are reported here.
was used to streak a Brilliant Green Sulfa Agar plate. Modified Moore's swabs (1, 2) were employed for the isolation of salmonellae from sewage. All the Brilliant Green plates were incubated at 37 °C for 24 hours and suspected Salmonella colonies were identified by biochemical tests according to standard methods (3). Serogrouping of the isolates was conducted in our laboratory using Salmonella polyvalent and groupspecific antisera (BBL). Serotyping was conducted in Salmonella Reference Laboratories abroad. RESULTS AND DISCUSSION
MATERIALS AND METHODS
The bacteriological examination of farm animals for salmonellae was carried out on necropsy specimens consisting of liver, spleen, lymph node, or faeces. The specimens were cultured directly on Brilliant Green Sulfa Agar (Difco) plates. They were also enriched in Selenite Broth (Difco), (w/v ratio, 1:10), incubated overnight at 37 °C and then subcultured on Brilliant Green Sulfa Agar plates. Twenty-five grams of each animal feed sample were cultured in 250 ml of Selenite Broth and incubated at 37 °C for 18-24 hours. The dry sludge samples were cultured in the same manner, but were incubated at 41.5 'C. One loopful of each of the selenite cultures * Requests for reprints should be addressed to Mr H. M. AlNakhli. l Associate Professor of Microbiology, Faculty of Medicine, American University of Beirut, Lebanon. Currently serving as Bacteriologist, Regional Agriculture and Water Research Center, under the auspices of the Saudi Arabian-United States Joint Commission on Economic Cooperation (JECOR). 2 Research Associate, Faculty of Agriculture, American University of Beirut, Lebanon. Currently seconded to the Regional Agriculture and Water Research Center. 3 Research Assistant, Regional Agriculture and Water Research Center, P.O. Box 17285, Riyadh, Saudi Arabia.
4232
The number and type of samples examined and the number of samples positive for salmonellae are shown in Table 1. A total of 264 salmonellae representing 65 different species or serotypes were isolated for the first time in Saudi Arabia from various sources. The six most frequently isolated Salmonella species and serotypes were: livingstone, concord, Table 1. Salmonellae isolated from farm animals, animal feed, sewage, and sludge in Saudi Arabia, 1977-80 Type of sample Farm animals bovine ovine
caprine chicken Animal feed Sewage
Sludge
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No. of samples examined
No. positive for Salmonella
1 010 400 172 16 422 346 61 47
95 6 32 3 54 42 37 22
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N. H. NABBUT ET AL.
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"S. schottmuelleri" (invalid), lille, S. typhimurium, cerro (Table 2). S. typhimurium had the widest distribution as it was encountered in cattle, sheep, and goats, and in animal feed. It was the predominant species in sheep while serotypes concord and livingstone were the most common in chickens. "S. schottmuelleri" (invalid) and serotype lille were isolated exclusively from sewage and animal feed, respectively. The above species and serotypes, and many others, are potentially capable of causing animal salmonellosis which brings about substantial economic losses to the livestock and poultry industries through the death of young animals, decreased milk and egg production, and reduced value of contaminated products. Of the 346 feed samples examined, 42 (12.13%) yielded 19 different Salmonella species and serotypes; lille, new-haw, and livingstone were the predominant serotypes. Four of the samples contained two serotypes and two samples had three. This finding is in agreement with data reported by other workers (4, 5). Contaminated animal feeds are considered as potential sources from which farm animals may acquire salmonellae. Previous reports from various countries have indicated that animal feeds are more or less contaminated with salmonellae (6-9). In addition to the risk of clinical salmonellosis in animals ingesting contaminated feed, human subjects may be infected as a result of consuming infected meat. Salmonellosis is a health problem that is likely to increase in importance from the medical and veterinary aspects, particularly in developing countries. A Salmonella food poisoning outbreak occurred in Riyadh, Saudi Arabia in 1980 (10). Twelve persons out of 21 who attended a home dinner were affected and 6 of these required the care of a physician, although none required hospitalization. All the patients showed symptoms characteristic of salmonellosis, including fever, diarrhoea, nausea and/or
vomiting, abdominal pain, and general fatigue. The incubation period ranged from 14 to 32 hours with an average of 18 hours. The epidemiological and bacteriological findings indicated that the incriminated food vehicle was roast beef contaminated by Salmonella serotype muenster. The origin of the meat was presumed to be a calf with clinical salmonellosis that was subjected to emergency slaughter. Similar outbreaks due to salmonellae, especially those accompanied by mild symptoms of gastroenteritis, are rarely reported to the public health authorities in the Kingdom. The isolation of 30 different Salmonella species and serotypes from sewage and 11 from sludge indicates that both sewage and sludge play a role in the dissemination of salmonellae in the environment and possibly to man and animals. On 23 occasions more than one Salmonella species or serotype was isolated from the sewage samples whereas only 4 of the sludge samples contained more than one. This dissemination would be more significant if inadequately treated sewage effluents and sludges were used for the irrigation of crops or as soil conditioners. Sewage may be an important indirect source of salmonella infection in animals. Cases of salmonellosis in cattle may result from the application of sewage and cattle slurry to land (11, 12), but it is difficult to predict how easily cattle grazing on contaminated pastures might become infected. This subject requires further extensive investigation. Similar studies in developed countries have led to a better understanding of the epidemiology of salmonellosis under the particular socioeconomic conditions of those countries. Our data indicate somewhat similar epidemiological patterns in Saudi Arabia. The data obtained in this study indicate the need for the institution and enforcement of preventive and control measures for reducing the public health and animal health hazards of salmonellosis.
ACKNOWLEDGEMENTS We express our thanks and appreciation to Mrs S. Dixon of the Salmonella Reference Laboratory, Adelaide, South Australia, Dr W. Sojka of the Central Veterinary Laboratory, Weybridge, England, Dr B. Rowe of the Central Public Health Laboratory, Colindale, England, and Dr M. Gershman of the Department of Microbiology and Animal Pathology, University of Maine, USA, for the serotyping of the Salmonella cultures.
RESUME ESPECES ET SEROTYPES DES SALMONELLES ISOLES A PARTIR DES ANIMAUX DE LA FERME, D'ALIMENTS POUR ANIMAUX, DES EAUX USEES ET DES BOUES EN ARABIE SAOUDITE
Pres de 2 000 serotypes de Salmonella ont djai et decrits et tous sont consideres comme potentiellement pathogenes
pour l'homme ou les animaux ou bien pour l'un et les autres; ils different quant a leur adaptation i I'h6te, au syndrome
SALMONELLAE IN SAUDI ARABIA
pathologique produit et a la distribution geographique. La presence de salmonelles chez le betail et la volaille ainsi que dans les sources environnementales n'entraine pas seulement des pertes economiques parmi ces animaux, mais constitue aussi un danger potentiel pour la sante humaine. Un total de 264 salmonelles representant 65 especes et
807
serotypes differents a et isole en 1977-80, pour la premiere fois en Arabie saoudite A partir de diverses especes animales, d'aliments pour animaux, d'eaux usees et de boues. Les six especes ou serotypes de Salmonella les plus frequemment isoles etaient: livingstone, concord,
