Isolation, identification and antimicrobial susceptibility profiles of <i>Salmonella</i> isolates from dairy farms in and around Modjo town, Ethiopia

Abstract

Foodborne bacterial diseases are a serious challenge to human and animal health. Salmonella is a zoonotic foodborne pathogen and the etiologic agent of salmonellosis. A cross-sectional study was conducted from January 2016 to April 2016 on small scale and large scale dairy farms in and around Modjo town, Ethiopia. The main objectives of the study were to isolate and identify Salmonella from lactating cows, personnel's' and equipment at farms and to determine the in vitro antimicrobial resistance profiles of the isolates. A total of 266 samples consisting of fresh cow milk, fecal sample, pooled milkers' hand swab, pooled bucket swab, tank swab, and tank milk were collected from 21 dairy farms (n=20 smallholders, n=1 large scale farm). The samples were examined for the presence of Salmonella following standard techniques and procedures outlined by the International Organization for Standardization. Kibry-Bauer disk diffusion test was used for the antimicrobial susceptibility testing. Salmonella was isolated from 28/266 (10.5%) of the total samples. Out of the 28 Salmonella isolates, 18 (64.3%), 3 (10.7%) and 7(25%) were from lactating cows, personnel's', and equipment, respectively. Out of the 28 isolates subjected to antimicrobial susceptibility testing, all isolates were resistant to at least one or more antimicrobials tested. Accordingly, 96.4% (27/28), 82.1% (23/28) and 75.0% (21/28) isolates were resistant to tetracycline, kanamycin and nalidixic acid, respectively. Multiple drug resistance (resistance to two or more antimicrobials) was detected in 27(96.4%) of the isolates. Multiple antimicrobial resistance was observed in 100% (18/18), 7.4% (2/23) and 100% (7/7) of isolates obtained from lactating cows, personnels', and equipment, respectively. High proportion of multiple antimicrobial resistant isolates (96.4%) in 93Fufa Abunna et al., Ethiop. Vet. J., 2017, 21 (2), 92-108 the dairy farms alerts concern for animal and public health as these drugs is used widely for treatment and prophylaxis in animals and humans.

Review of the prevalence of foodborne pathogens in milk and dairy products in Ethiopia

“…The microbial safety of these products is highly variable, as determined by bacterial foodborne pathogen occurrence; which poses a health risk to consumers. In the following sections, we report a summary of the literature review on the prevalence of four major bacterial foodborne pathogens ( Abera et al., 2016 , Abunna et al., 2017 ; Abunna et al., 2018a , Abunna et al., 2018b , Abunna et al., 2018c , Addis et al., 2011 , Adugna et al., 2015 , Adugna et al., 2013 , Banti, 2018 , Bedasa et al., 2018 , Desta, 2013 , Disassa et al., 2017 , Ejo et al., 2016 , Fisseha, 2017 , Garedew et al., 2015 , Gebretsadik et al., 2011 , Girma and Abebe, 2018 , Mekuria and Beyene, 2014 , Mengesha et al., 2009 , Molla et al., 2004 , Mossie and Dires, 2016 , Muhammed et al., 2013 , Mulaw, 2017 , Reta et al., 2016 , Seyoum et al., 2015 ; Tadesse and Dabassa, 2012 , Tesfaw et al., 2013 , Tesfay et al., 2013 ).…”

“…In this review, fifteen peer-reviewed publications were identified and reviewed to summarise the prevalence of Salmonella spp. in Ethiopian milk and dairy products ( Abate et al., 2013 , Abera et al., 2016 , Abunna et al., 2017 , Abunna et al., 2018a , Abunna et al., 2018b , Addis et al., 2011 , Adugna et al., 2013 , Banti, 2018 , Ejo et al., 2016 , Mossie and Dires, 2016 , Mulaw, 2017 , Reta et al., 2016 , Tadesse and Dabassa, 2012 , Tesfaw et al., 2013 , Tesfay et al., 2013 ). In addition, two non-peer reviewed theses ( Dailey, 2011 , Hunduma, 2018 ) were identified as relevant but were not included in further analysis and data summary.…”

“…Three studies were conducted in Addis Ababa, of which two collected samples from urban farms ( Addis et al., 2011 , Banti, 2018 ) and one purchased samples at retail stores ( Tesfaw et al., 2013 ). Seven studies were conducted in the Oromia region, five of which were conducted in towns less than 100 km away from Addis Ababa ( Abate et al., 2013 , Abunna et al., 2017 , Abunna et al., 2018a , Mossie and Dires, 2016 ) and two were conducted in towns over 100 km from Addis Ababa ( Abunna et al., 2018b , Tadesse and Dabassa, 2012 ). Two studies were conducted in Amhara region ( Ejo et al., 2016 , Mulaw, 2017 ), three in Somali region ( Abera et al., 2016 , Adugna et al., 2013 , Reta et al., 2016 ) and two in Harar ( Adugna et al., 2013 , Tesfay et al., 2013 ).…”

“…Two studies were conducted in Amhara region ( Ejo et al., 2016 , Mulaw, 2017 ), three in Somali region ( Abera et al., 2016 , Adugna et al., 2013 , Reta et al., 2016 ) and two in Harar ( Adugna et al., 2013 , Tesfay et al., 2013 ). Twelve studies reported employing a cross-sectional study design ( Abera et al., 2016 , Abunna et al., 2017 , Abunna et al., 2018a , Abunna et al., 2018b , Banti, 2018 , Ejo et al., 2016 , Mossie and Dires, 2016 , Mulaw, 2017 , Reta et al., 2016 , Tesfaw et al., 2013 ), of which seven reported a sample size calculation based on the prevalence estimates between 2.1% and 50% ( Abunna et al., 2018b , Abunna et al., 2017 , Addis et al., 2011 , Banti, 2018 , Mossie and Dires, 2016 , Mulaw, 2017 , Tesfaw et al., 2013 ) (see Table 1 ).…”

“…(2016) Amhara Gondar Feb 2014 to Dec 2015 Purchased from restaurants, hotels, cafeterias, pastry and retail shops Cross-sectional Random sampling ISO-6579:2002 Biochemical tests: TSI, urea agar, LIA, VP, methyl red, Simmons citrate and indole test Mossie and Dires (2016) Oromia Debre Zeit Dec 2013 to Apr 2014 Collected from bulk tank milk from household/small holders, supermarket and large dairies Cross-sectional Sample size determined based on P = 2.1%, d = 5%, confidence = 95% ISO-6579:2002 Biochemical tests: indole, methyl red, VP, urea broth, LIA and TSI Reta et al. (2016) Somali Jigjiga Mar 2013 to Jan 2014 Collected from individual farmers, milk collectors and milk vendors Cross-sectional Not stated Pre-enrichment in peptone water, enrichment in Selenite cysteine broth, isolation in XLD Biochemical tests: LIA, TSI, urea agar, VP broth, methyl red and indole test Abunna et al. (2017) Oromia Modjo Jan 2016 to Apr 2016 Collected at dairy farms from the udders of cows and the bulk tank Cross-sectional Random sampling.…”