Prevalence, antibiotic resistance and biofilm formation of Salmonella in raw chicken meats at selected slaughterhouses in Peninsular Malaysia
Salmonella is one of the most common causes of foodborne diseases. The objectives of this research were to isolate and identify Salmonella from raw chicken meat, determine its antibiotic resistance and its ability to form biofilm on the surfaces using microtitre plate surface in a growth media at...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/84510/1/FSTM%202019%2033%20ir.pdf |
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| Summary: | Salmonella is one of the most common causes of foodborne diseases. The objectives of
this research were to isolate and identify Salmonella from raw chicken meat, determine
its antibiotic resistance and its ability to form biofilm on the surfaces using microtitre
plate surface in a growth media at different incubation period. Raw chicken meat was
obtained from selected slaughterhouses located in four different zones in Peninsular
Malaysia; Northern Zone (States of Perlis, Kedah, Penang and Perak); Central Zone
(States of Selangor, Negeri Sembilan and Melaka; Southern Zone (States of Johor) and
Eastern Zone (States of Terengganu, Kelantan and Pahang). The samples were collected
and isolated at the Veterinary Public Health Laboratory (VPHL), Department of
Veterinary Services (DVS), Sepang, Selangor. Isolation and identification of samples
were performed using an in-house conventional (VPHL) culture method adopted from
the American Association of Analytical Chemists (AOAC, 1995), the Food Safety and
Inspection Services of USDA (FSIS, 1998) and the Australian Standard (AS 1766.2.5,
1991). Positive isolates were serotyped at the Veterinary Research Institute, Ipoh Perak
using the White-Kauffmann-Le Minor scheme comprising of commercial somatic and
flagellar antisera. The antibiotic resistance of 135 Salmonella isolates was investigated
via the Kirby-Bauer disk-diffusion method, using 12 antibiotics. The biofilm-forming
ability of the isolates was assessed using two media; a tryptic soy broth (TSB) and a 1/20
TSB with incubation periods of 24 and 48 hours at 37 °C. Crystal violet staining was
used for the quantification of Salmonella isolates based on the difference between optical
density measurements of the test and negative control samples (ΔOD590nm). It was found
that 17.31% (135/780) of the raw chicken meat tested positive for Salmonella.
Serotyping of the total 135 isolates demonstrated that 87 (64.44%) belonged to 12
different serovars; S. Corvallis, S. Brancester, S. Enteritidis, S. Albany, S. Typhimurium,
S. Braenderup, S. Hindmarsh, S. Hiddudify, S. Bellevue, S. Duesseldorf, S. Cyprus and
S. Indiana. The results showed that the Salmonella isolates had the highest percentage of
resistance to erythromycin (87.41%) and tetracycline (85.19%). Salmonella isolates were
also resistant to sulphamethoxazole/trimethoprim (55.55%), ampicillin (26.63%), streptomycin (29.63%), enrofloxacin (22.96%) and nalidixic acid (17.04%). In contrast,
lower percentage of resistance was observed against gentamicin (7.41%), cephalothin
(5.96%), ceftriaxone (3.70%) and amoxicillin-clavulanic acid (2.22%). All Salmonella
isolates were susceptible to ciprofloxacin (CIP). The multiple antibiotic resistance
(MAR) index varied from 0.08 to 0.75. A total of 93 isolates (68.88%, 93/135) were
multi-drug resistant. Meanwhile, more than 85% of 135 Salmonella isolates were able to
form biofilm in TSB and 1/20-TSB media. A greater quantity of Salmonella were able
to produce biofilm 1/20-TSB (90.37%) compared to TSB (88.15%), respectively. The
maximum biofilm (94.81%) formed by Salmonella isolates was at 24 hours incubation
in 1/20-TSB whereas 88.89% biofilm formed in TSB. The occurrence and antibiotic
resistance profiles of Salmonella isolates in slaughterhouses could promote awareness
on controlling Salmonella at all production stages of raw chicken meat in Peninsular
Malaysia. The ability of Salmonella to form biofilm could indicate common factors
promote biofilm formation; thus further work could develop interventions to reduce this
incidence. |
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