Serotyping, PCR, phage-typing and antibiotic sensitivity testing of Salmonella serovars isolated from urban drinking water supply systems of Nepal

Abstract

Aims: To study the occurrence and diversity of Salmonella serovars in urban water supply systems of Nepal. Methods and Results: Occurrence of Salmonella was detected in 42 out of 300 water samples by enrichment culture technique in selenite F broth followed by plating on Salmonella Shigella agar. A total of 54 isolates identified to genus level by standard tests were subsequently confirmed by serotyping, phage typing and PCR detection of virulence genes (inv A and spv C). The predominant serotype was Salmonella Typhimurium, followed by Salm. Typhi, Salm. Paratyphi A and Salmonella Enteritidis. Most of the Salm. Typhi isolates were E1 phage type followed by UVS4, A and UVS1. All isolates of Salm. Paratyphi A and Salm. Enteritidis were an untypable (UT) phage type. The majority of isolates were multi‐drug resistant as revealed by Kirby–Bauer disc diffusion technique. Ceftriaxone resistant isolates of Salm. Enteritidis indicated the presence of one of the ESBL genes, blaSHV, whereas the genes blaTEM and blaCTX were absent. Conclusions: The microbiological quality of the urban water supply is poor and indicates possibility of fatal outbreaks of enteric fever and related infections in Nepal. Significance and Impact of the Study: The present study will be useful in water borne disease control and prevention strategy formulation in Nepal and in the global context.

Occurrence of <i>Salmonella</i> in drinking water samples of urban water supply system of Kathmandu

“…Similar result was reported by Bhatta et al (2007). Ten Salmonella isolates were assayed against 8 different antibiotics.…”

“…However, resistance was most commonly directed towards amoxicillin, chephalexin and ceftizoxime respectively. Similarly, Bhatta et al (2007) examined 54 isolates of Salmonella spp. for resistance to different antibiotics.…”

Salmonellae in the Environment

“…Sewage effluents, agricultural run-off and direct deposit of faecal materials from wild animals and birds are the major sources of the bacteria in aquatic environments (Alcaide et al, 1984;Baudart et al, 2000;Johnson et al, 2003;Abulreesh et al, 2005). Salmonella species have been found in almost all types of aquatic environments that receive faecal contamination, that include drinking water (Bhatta et al, 2007), rivers (Pianetti et al, 1998;Polo et al, 1998;Polo et al, 1999;Dionisio et al, 2000;Lemarchand & Lebaron, 2003;Arvanitidou et al, 2005;Haley et al, 2009), lakes (Claudon et al, 1971;Arvanitidou et al, 1995;Sharma & Rajput, 1996), ponds (Shellenbarger et al, 2008), marine waters (Matinez-Urtaza et al, 2004a;Martinez-Urtaza et al, 2004b;Martinez-Urtaza & Liebana, 2005;Harakeh et al, 2006), run-off water (Claudon et al, 1971), treated and untreated wastewater (Ho & Tam, 2000;Melloul et al, 2002;Espigares et al, 2006, Mafu et al, 2009 worldwide. Abulreesh et al (2004) were unable to detect salmonellae in water samples from a village pond that receives direct faecal contamination from waterfowl, nevertheless, they managed to isolate the bacterium from bottom sediments of the same pond.…”

Financing Watershed Services in the Foothills of the Himalayas

“…Interest in drinking water quality is to be expected since water borne diseases are a major problem in Nepal [58,59]. The results also seem reasonable because Dharan residents commonly use tap water for drinking and cooking, while they pump ground water for other uses.…”