Incidence and molecular detection of Salmonella enterica serogroups and spvC virulence gene in raw and processed meats from selected wet markets in Metro Manila, Philippines

Abstract

Abstract-A simple and specific detection method for Salmonella enterica was applied to determine its incidence in raw and processed meats purchased from selected wet markets in Metro Manila, Philippines. A total of 320 raw and processed meat samples were analysed for the presence of S. enterica and S. enterica possessing spvC gene of the virulence plasmid. Polymerase chain reaction (PCR) revealed that 30.63% (98/320) were positive for S. enterica and 2.81% (9/98) of S. enterica-positive samples were also positive for the spvC gene. S. enterica was identified from chicken samples (67.5%), ground pork (65%), beef (52.5%), sausage (longganisa) (25%), cured pork meat (tocino) (20%), burger patty (12.5%), and meatloaf (embotido) (2.5%). Positive samples were further analysed for O-serogrouping targeting S. enterica serogroups A, B, C1, C2, D, and E1. Our findings revealed that the raw and processed meats tested were contaminated with more than one serogroup in a sample. Samples were found positive for S. enterica serogroups E1 (78.57%), C1 (29.59%), C2 (20.41%), B (17.35%) and D (6.1%). No samples were found positive for S. enterica serogroup A. This is the first report on the use of multiplex PCR for the detection and characterization of S. enterica in raw and processed meats in the Philippines. Data on incidence of S. enterica and its serogroups found in raw and processed meats in selected Philippine wet markets gathered from this study can be used for further research on epidemiology and related topics.

PCR-based detection and serovar identification of Salmonella in retail meat collected from wet markets in Metro Manila, Philippines

“…studies in Metro Manila demonstrated that Salmonella serogroup O:3 was the most dominant serogroup detected in raw and processed meat (78.57%) from wet markets [13], and slaughtered swine (75%) from slaughterhouses [15]. However, Ng & Rivera [14] found that serogroup O:4 (73%) was the most frequently isolated serogroup in slaughtered swine in abattoirs followed by serogroup O:3 (24%).…”

“…Quality of the market sanitation and practices were ranked on an ordinal scale of five values ranging from poor to very good (S1 Appendix). [ [13][14]. Briefly, 25 g meat sample was aseptically manually homogenized and inoculated into 225 ml buffered peptone water (BPW; BD Diagnostics System Difco TM USA) in a sterile bottle.…”

“…Two milliliters of culture from RV broth (TEP I) and 1 ml of Salmonella culture in TSB (TEP III) were centrifuged at 15,330 ×g for 5 min [13]. The resulting supernatant was discarded while the pooled bacterial pellet was suspended in 1 ml phosphate-buffered saline (PBS).…”

“…However, this type of market has been linked to major diseases due to poor hygienic conditions [22]. Various studies have detected wet markets as an important source of Salmonella, where prevalence ranged from 6.8-87.5% in various retail meat [13,[22][23][24][25][26][27][28][29][30]. This study found that 415 (57.64%) of 720 purchased raw and processed meat products were contaminated with Salmonella using PCRbased Salmonella detection ( Table 2).…”

“…This study aimed to detect Salmonella spp. from various raw meat and meat products collected from nine selected Metro Manila wet markets using PCR-based detection assays described by Ng & Rivera [14] and Soguilon & Rivera [13], and classify Salmonella based on their O-serogroups and serotypes using PCR-based serotyping assays. This study can contribute to the epidemiology of salmonellosis in the Philippines, particularly on reservoirs of clinically important serotypes.…”