T HE COLLECTED 942 samples (6 organ/bird) from 157 birds taken from 34 broiler chicken farms aged 2-31 days including 13 and 21 clinical diseased and apparently health flock as well as 221 hatchery samples. Samples were tested for isolation of Coagulase negative staphylococcus (CoNS).Results of isolation from chicken flocks with clinical signs are 9/13(69.23%) were positive. Positive samples (11/354, 3.11%) including : 3liver, 4 kidney, 2 intestine, 1 air sac and 1 nasal sinus. Out of apparent healthy flocks 8/21 (38.95%) were positive. Positive samples (15/ 588, 2.55%) including 3 liver, 2 kidney, 4 intestine, 3 lung, 2 air sac and 1 nasal sinus. Results showed that 15 positive flocks out of 34 flocks (34.09%) with 26 Staphylococcus isolates from 942 samples (2.77%) including 6 liver, 6 kidney, 6 intestine, 4 lung, 2 air-sacs and 2 nasal sinus with rate of 3.82%, 3.82%, 3.82%, 2.55%, 1.27% and 1.27%; respectively. Also12 isolates out of 26 (46.15%) were CoNS include 8 S. xylosus (75 %), 2 S. scuiri (16.67%) and 2 S. lentus (16.67%).Hatchery samples reveals the isolation of 26 staphylococcus isolates (11.76%). The tested 108 fertile eggs and dead in shell embryos resulted in 14 and 12 isolates in rate of 12.96% and 13.79%; respectively. Ten isolates were CoNS (38.46%) and represented 4.52% out of total samples including 8 S. xylosus and 2 S. scuiri. Eight S. xylosus was 6 (5.55%) from infertile eggs and 2 (2.29 %) from dead in shell, While the 2 S. scuiri (1.85%) were obtained from infertile eggs.The tested CoNS isolates showed 100% resistance to Oxytetracycline 30 µg/ml (T30), Trimethoprime + Sulphamethexole 2.25/23.75 µg/ml (SXT) , Calindamycin 2 µg/ml (DA) and Oxacillin 30 µg/ml (OX). All isolates were 100% susceptible to Vancomycin 30 µg/ ml (VA) and 90% susceptibility to Enrofloxacin 5 µg/ml (ENR). Multidrug resistance was detected in form of resistance to 9, 4 and 5 out of tested 13 antibiotics in 2 S.lentus , 5 S. scuiri and 15 S. xylosis; respectively.Ten isolates were tested for the presence of 7 resistance gens including: mecA , tetK, blaZ , kan , ermC, icaD, bab gene. Seven isolates from the tested 10 (70%) having 4 resistance gens. The most detected gens are mecA tetK, blaZ and ermC where it was detected in 90, 80, 60 and 90% respectively. Kan , icaD and bab gens were detected in rate of 30.0 and 0 %; respectively.In conclusion: CoNS could isolated from healthy and diseased chicken flocks as well as from chicken hatchery. The obtained isolates were multidrug either phenotypic and /or genotypic resistant. Good hygienic measures in both chicken farms and hatchery with monitoring of drug resistance of CoNS those act as source for resistance genes to bacterial pathogens and their importance to the poultry and public health are recommended.

O NE HUNDRED and sixty, 1-day old broiler chicks were grouped into 4 equal groups, at the 10 th day birds of groups 1-3 were s.c inoculated with 0.5 ml containing y 1.5x 10 8 of S.xylosis, S. sciuri and S.lentus; respectively and group 4 was noninfected control. Clinical signs in infected groups started at 2-3dpi as general signs. Signs disappear in Ciprofloxacillin treated subgroups 24 hr post treatment and lasted to the 7 th day in non treated. Average body weight gain in S.xylosis infected non treated was the highest (813.90 gm), followed by S. scuiri (778.50gm) and 773.75 in S. lentus infected treated. FCR was the highest in control (1.69 treated and 1.74 non treated) followed by S. scuiri infected (1.81 non treated and 1.82 treated) and the lowest 1.94 was in S.lentus infected non treated. S. sciuri was reisolated from intestine and spleen (5 th dpi) and from intestine (7 and 10 dpi). While S.lentuswas reisolated from intestine , liver and spleen (3 rd dpi) ; from intestine and spleen (5 th dpi) and intestine (10 th dpi). Histopathological lesion was recorded in infected group as hemorrhages with sinusoidal dilation, focal areas of vacuolar degeneration , fatty degeneration and shrinkage of hepatocytes in liver, necrotic changes of lymphocytes and vacuolion of corpuscle in spleen. Leucocytic infiltration , degeneration and necrosis of epithelium surface and intraepithelial as well as submucosal leucoytic infiltration were seen in intestine. In conclusion the injected organisms induce mild subclinical disease with recording of histopathological lesions in liver, spleen and intestine. This area needs more investigation to explore pathogenicity of CoNS in chickens.