Antibiotic Resistance And Plasmid Contents Of Salmonella Serotypes Isolated From Raw Milk Khilud K.Nazal, Najim H.Najim , Mohammed A. Hassem

Abstract

This study lasted for eight months .The main objectives of the study were
to identify the main sources of raw milk pollution with Salmonella with a
special emphasis on determination of their serotypes. The relationship between
their resistance to antibiotics and their plasmide contents were also studied.
Six hundred raw milk samples collected randomly at weekly intervals where the
first (300) samples were from the individual milk cans (50 Kg each) at the
producers homes in Abu-Ghraib village while the second (300) samples were
collected from the scale bulk tanks (2 tons) inside the milk reception and
collection center at the same village.
In addition to that (200) swabs were taken from four different location (50
swabs for each) namely: the teats, milkers hands, the inner surface of the milk
cans and the sedimemts that were precipitated at the bottom of the scale bulk
tank.Data revealed that 5% of the milk cans and 7% of the scale bulk tank were
contaminated with Salmonella besides the percentage of the Salmonella isolates
from different swabs location were as 10% , 30% , 8% and 52% out of the teats,
inner surface of milk cans, milker’s hands and sediments of the bulk tanks
respectively .
Seven serotypes of Salmonella were identified from both milk samples and
swabs including S. typhimurium 40 %, S. anatum 26.67%, S. Kottbus 13.33 %,
S. infantis 6.67%, S. dublin6.67%, S. java 3.33% and S. typhi 3.33%.
Antibiotic sensitivity test for different antibiotics revealed that most
Salmonella isolates were resistant to two antibiotics where (36.66%)of the
isolates were resistant to Sulphamethazol, (16.66%)were resistant to tetracycline
, (10%) were resistant to Streptomycin and (3.33%) were resistant to each of
Chloramphenicol , Kanamycin and Ampicillin.
The extraction of the DNA-plsmide revealed that seven out of ten isolates
contained large, individual plasmids size of (50-70) Killo Base (KB) while the
others three isolate were free from such plamid.