الفهرس 
INTRODUCTION
Isolation of Salmonella microorganism from chickenOnly 14 pages are availabe for public view
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Abstract
An epidemiological investigation on Salmonellosis infection in broiler and native chickens was carried out on 100 samples of cloacal swabs from living chickens and 151 samples of freshly dead chickens were examined for post-mortem and bacteriological examination of internal organs. The results revealed that eleven salmonella strains were isolated. Morphological, colonial and biochemical characters of these isolated salmonella strains were identical to the general characters of this species.
The result of serological identification appeared five serotypes including S.typhymurium (3strains), S.entertidis (3 strains), S.kentucky(2 strains), S.virchow (1strains), S.anatum (1strain) and untypable serotype (1 strain).
The overall incidence of Salmonella infection in commercial broiler and native chickens was 4.4% in The New Valley province. The cecum was the best site for isolation of Salmonella from the internal organs of freshly dead chickens followed by liver , cloacal swabs and intestine with a percentages 3.45% , 2.1% , 2% and 0.7% respectively. While there is no Salmonellae could be isolated from yolk sac.
The incidence of Salmonella isolates according to age of chickens appeared that first week till the third week were the most susceptible age for Salmonella Infection then decrease with old ages. It was found that the incidence of Salmonella infection according to the type of breed was higher in commercial broiler than native breed with a percentage rate (7.4%) , (1.5%) respectively. the recorded clinical signs due to natural infection are depression, diarrhea, emaciation, ruffled feather, huddle together, DROP in egg production . the post mortem lesion appeared on freshly dead chickens were enlargement and congestion of internal organ ,hemorrhages in heart ,necrotic foci in liver, fibrinous pericarditis, hepatitis, catarrhal and hemorrhagic enteritis and ureter were distended with urates.
The pathogenicity of Salmonella isolates was studied in one- day old chicks. The result revealed that S.typhimurium and S.entertidis were pathogenic for one- day old chicks with mortality rate 20%, 40% respectively, but other serotype not appeared any mortalities rate. Experimentally infected chicks appeared depression , huddle together, ruffled feather, gasping air , there was whitch diahrria pasting vent, all survived bird show sever retardation in growth, further clinical sign appeared such as arthritis in S.typhimurium and S.virchow. The main lesions were enlarged and congestion of internal organs especially liver, focal necrosis on liver surface, unabsorbed yolk sac tinged with blood, cattahrral enteritis and mild fibrinous pericarditis and hepatitis. The bacteriological examination of cloacal swabs showed that the chicks was execreting Salmonella organisms till the end of experiment in irregular pattern and became carrier for infection . The bacteriological examination of organs revealed that all organ were positive especially intestine, cecum and liver .
During testing of Salmonella isolates to antibiotic drugs in vitro they appeared high resistant rate to most antibiotic drugs. also it was observed multi drug resistant (MDR) in all isolates except S. typhymurium which was sensitive to most antibiotics but resistant to amoxicillin and less sensitivity to ofloxacin especially the group of quinolones (ciprofloxacin , ofloxacin , levofloxacin) which consider the drug of choice for human being treatment except S.typhimurium were sensitive to ciprofloxacin, levofloxacin and decrease sensitivity to ofloxacin and S.virchow was sensitive to levofloxacin and resistant to ciprofloxacin and ofloxacin.
from the results obtained in this work , it could be concluded that :-
1- The incidence of Salmonellae infection in broiler and native chickens in the new valley governorate was 4.4% from living and freshly dead carcasses. It becomes nearer to which recorded by the National Salmonella Control Programme (2004). So it is time to do a national plan to investigate the incidence of Salmonella infection in chickens in all provinces of Egypt and finding strict national programme for complete elimination of this disease.
2- The cecum was the predilection site for the isolation of Salmonella organisms from internal organs with a percentage rate 3.45% then liver and cloacal swab with a percentage rate 2.1%, 2% respectively then intestine with a percentage rate 0.7%.
3- The first 3 weeks age were the most susceptible ages for Salmonella infections then the incidence rate decreased with old age.
4- The prevalence of Salmonella infection in native chickens was less than from commercial broiler farms due to their developing immunity, so studies must be done about cross breed to develop genetic characters related to immunity in commercial broiler farms and get it more resistant for Salmonellosis and other diseases.
5- Experimental infection revealed that :-
a- S. typhimurium and S. entertidis were pathogenic for one day old chicks with mortality rate 20%, 40% respectively, but other serotype not appeared any mortalities rate.
b- One day old chicks appeared the same clinical signs and lesions related to Salmonellosis.
c- Fecal shedding of Salmonella organisms in experimentally infected chicks showed that the chicks which survived after post infection became carrier for disease and excreted the micro-organisms in feces in irregular pattern till the end of experiment which appear to be high importance and should be taken into consideration in studying the carrier state of Salmonella serotypes among the chickens that the authorities must take this finding into consideration in planning further work for the control of the disease in Egypt .
6- In vitro sensitivity test, our results indicated that most Salmonella isolates became resistant to the most important antibiotic drugs and isolation of antimicrobial resistant Salmonella serotypes including multi-drug resistance poses a concern to public health authorities and the general consumers and this due to the use of antibiotics either in poultry feed as growth promoting factor or in preventing programmes for long period. Regarding this problem, therapeutic agents must not be given until sensitivity test firstly will be done and from other side we advice with the prevention of the use of antibiotics as feed supplement which used in poultry therapy.
It may be concluded that Salmonellosis has emerged as one of the most serious problems having adverse effect not only in poultry but also in the danger of being transmitted to human beings through the consumption of the infected poultry meat, eggs and egg products. In future for the control of Salmonella infection in poultry, vaccine production and gene level study need to be performed in Egypt to save the poultry industry.