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. 2020 Feb 10;9(2):73.
doi: 10.3390/antibiotics9020073.

Molecular Characterization Of Pathogenic Salmonella Spp From Raw Beef In Karachi, Pakistan

Muhammad Altaf Hussain  1 , Wan Wang  1 , Changbao Sun  1 , Liya Gu  1 , Zhijing Liu  1 , Tong Yu  1 , Yasin Ahmad  2 , Zhanmei Jiang  1 , Juncai Hou  1
Affiliations

Molecular Characterization Of Pathogenic Salmonella Spp From Raw Beef In Karachi, Pakistan

Muhammad Altaf Hussain et al. Antibiotics (Basel). .

Abstract

The aim of the present study was to estimate the prevalence of Salmonella and investigate the dominant serovars distribution in raw beef and to screen the isolated serovars for the prescense of beta-lactamases and virulence genes. A total of 150 samples of raw beef sold at butcher shops (n = 75) and supermarkets (n = 75) in Karachi city were collected (50 samples each from muscles, lymph nodes, and minced beef). The samples were cultured according to the ISO-6579-1guidlines. The overall prevalence of Salmonella strains was found to be 21.34%. A total of 56 isolates of Salmonella belonging to four serogroups (Salmonella Pullorum, Salmonella Enteritidis, Salmonella Typhimurium and Salmonella Choleraesuis) were isolated from beef muscles (12%), lymph nodes (24%) and minced beef (28%) samples collected from butcher shops (av. 21.34%). No Salmonella was detected in beef samples collected from supermarkets. S. Enteritidis contamination was highest (37.5 %), followed by S. Choleraesuis (30.4%), S. Pullorum (19.6%) and S. Typhimurium (12.5 %). Antibiotic susceptibility testing revealed that Salmonella isolates were highly resistant to Oxytetracycline (90%), Ampicillin (90.5%), Amoxicillin (81.1%), Tetracycline (76%), Neomycin, (79.8%) and Ciprofloxacin (61.4%). The Salmonella isolates examined were more susceptible to the Cephalosporin antibiotics such as Cefixime (43.2%), Cefepime (48.2) and Cefoxitin (49.8%). PCR based screening of blaTEM, blaCTX-M and blaSHV revealed that blaCTX-M and blaTEM were the dominant resistant genes in S. Enteritidis and S. Typhimurium followed by S. Pullorum and S. Choleraesuis whereas blaSHV was the least detected beta-lactamase in Salmonella isolates. Virulence genes screening revealed that at least five genes were present in all the serovars, highest being present in S. Enteritidis (12/17) and S. Typhimurium (12/17). S. Cholerasuis (5/17) carried the least number of virulence genes followed by S. Pullorum (6/17). The present data suggest that beef samples from butcher shops of Karachi city are heavily contaminated with MDR Salmonella. The presence of resistance and virulence genes in MDR strains of Salmonella may play a significant role in transmission and development of Salmonella infection in humans.

Keywords: Salmonella; antibiotic resistance; public health; raw beef; virulence factors.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Prevalence of Salmonella in total positive samples.
Figure 2
Figure 2
Prevalence of virulence factors in S. Enteritidis, S. Typhimurium, S. Pullorum and S. Choleraesuis.
Figure 3
Figure 3
PCR based screening of sopB (220), tolC (161bp) and spaN (504bp). Lane M represents 100bp ladder.
Figure 4
Figure 4
Prevalence of beta lactamases in S. Enteritidis, S. Typhimurium, S. Pullorum and S. Choleraesuis.
Figure 5
Figure 5
Resistance percentage of Salmonella to various antibiotics.
Figure 6
Figure 6
Salmonella culture morphology on SS agar and XLD agar.
See this image and copyright information in PMC

References

    1. Fung F., Wang H.S., Menon S. Food safety in the 21st century. Biomed. J. 2018;41:88–95. doi: 10.1016/j.bj.2018.03.003. - DOI - PMC - PubMed
    1. Käferstein F. Foodborne diseases in developing countries: Aetiology, epidemiology and strategies for prevention. Int. J. Environ. Health Res. 2003;13:S161–S168. doi: 10.1080/0960312031000102949. - DOI - PubMed
    1. Bosilevac J.M., Guerini M.N., Kalchayanand N., Koohmaraie M. Prevalence and characterization of Salmonella in commercial ground beef in the United States. Appl. Environ. Microbiol. 2009;75:1892–1900. doi: 10.1128/AEM.02530-08. - DOI - PMC - PubMed
    1. EFSA The European Union summary report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in 2014. Efsa J. 2014;12:3547. - PMC - PubMed
    1. Mahmood A.K., Khan M.S., Khan M.A., Khan M.A., Bilal M. Prevalence of Salmonella in diarrheic adult goats in field conditions. J. Anim. Plant Sci. 2014;24:98–102.

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