Virulence Profiling of Enterobacter Specie Isolated from Mass Gatherings of Pakistan

Abstract

Mass gatherings (MGs) have been recognized as a major risk for disease outbreak by World Health Organization. In Pakistan, there is tradition of hosting mass gatherings, which include religious festivals, political, cultural, sports, food, and musical events. In MGs, due to proximity of people, poor hygiene, and cross contamination, it can be source of outbreaks especially from food and abiotic surfaces. The Enterobacter spp. are emerging opportunistic pathogens and are widespread in environment. The study aimed to determine the phenotypic analysis of virulence factors of Enterobacte spp. isolated from food and abiotic samples from different mass gatherings of Pakistan. A total of 52 food samples and 73 abiotic samples were collected from different mass gatherings. From these food samples, 83 Gram positive cocci and Gram-negative rods isolates were obtained. Meanwhile, 142 bacterial isolates from abiotic samples were purified. From these samples, total 117 Gram negative rods were isolated, and only 23 isolates were confirmed to be Enterobacter spp. after morpho-chemical characterization from both food and abiotic samples. A total of 50 Enterobacter spp. were subjected to different phenotypic virulence assays. Among these 50 isolates, 27 Enterobacter spp. were previously identified from food and abiotic samples from MGs. Among 23 newly identified Enterobacter species, 12 were isolated from food samples and 11 were isolated from abiotic samples. In case of food samples, 4 Enterobacter spp. isolates were identified from regular MGs and 8 Enterobacter spp. were identified from special MG events. Among 27 previously identified Enterobacter species, 17 isolates were from food samples and 10 isolates were from abiotic samples. None of the Enterobacter isolate had hypermucoviscosity. The 14% isolates from abiotic samples had beta hemolysin activity. A total 96% of isolates showed positive results for haemagglutination with blood group A. The Congo red assay showed 24% isolates were strong biofilm former and MTP assay showed 46% were strong biofilm former. Overall, 23/50 isolates exhibited strong biofilm formation according to MTP assay, out of these 12(52%) isolates we from special MG events and 11(48%) were from regular MG events. A strong association of hemagglutination activity (blood group A) with biofilm formation ability was observed in 100% Enterobacter isolates. Similarly, strong association of beta haemolysin activity with hemagglutination activity (blood group AB) was observed in 100% Enterobacter isolates. Thus, the overall results suggest that pathogenic Enterobacter isolates were prevalent in these mass gathering. On basis of this study, it is suggested that there is a need for training of food handlers and strict compliance to food biosafety regulations is need of time to prevent possibility of food borne outbreaks in MGs.