ABSTRACT
Staphylococcus aureus is one of the most commonly identified bacteria that cause food poisoning by virtue of its variety of enterotoxins, Nasal and hand carriage of enterotoxigenic Staphylococcus aureus is an important source of staphylococcal food contamination in restaurants, therefore it is important to detect Staphylococcus aureus carriage among foodhandlers to prevent possible food contamination .The objective of the study was to detect prevalence of enterotoxigenic strains of staphylococcus aureus among food handlers in Zagazig City and to evaluate phenotypic [SETRPLA] versus genotypic [multiplex PCR] methods for detection of the staphylococcal enterotoxins. Two hundred and seventy swabs of [nose, hand and axilla] were collected randomly from 90 food workers; 3 swabs from each food worker. The swabs were inoculated on Mannitol Salt agar an incubated aerobically for 24 hours. Any suspected Staphylococcus aureus colonies were systematically identified according to standard methods. Staphylococcus aureus isolates were subjected to SET-RPLA test using SET-RPLA Toxin Detection Kit for phenotypic detection of enterotoxin production and Multiplex-PCR to genetically detect enterotoxigenic strains. Carriage rate among the food handlers was 55.5% representing 50 Staphylococcal aureus isolates from 90 food handler, the proportion of contaminated samples among 270 swabs was 18.5% [50/270]. 38[76%] out of 50 isolates were found to be enterotoxigenic by SET-RPLA and 42 [84%] out of 50 staphylococcal isolates were found to be enterotoxigenic genotypically by multiplex PCR. The number of isolates was significantly higher in nasal swabs than in hand or axillary swabs [?[2] =36.87 and p=0.0000]. Using REPLA, the number of enterotoxin producing organisms was significantly higher in nasal swabs [91.2%] than in hand [38.5%] or axillary swabs [66.6%][?[2] = = 14.48 and p = 0.0007]. Type A enterotoxin was the most common type [48%] followed by type D [18%], then type C [6%] while the least type was type A+B [4%]. It also shows that type A+B was isolated only from nasal swabs [2.9%] and type D was not found in axillary swabs. Using Multiplex PCR, gene type a was the most common type [48%] followed by gene type d [22%] then gene type c [6%] while the least type was genes type a+ b [4%]. It also shows that gene types a+b and b+d were isolated only from nasal swabs [5.9% each]. Compared with multiplex PCR, specificity and positive predictive value of RPLA were 100%, while sensitivity was 90.48% and negative predictive value was 66.67%. This study concluded that nasal and hand carriage of enterotoxigenic S.aureus by food handlers is an important source of staphylococcal food contamination in restaurants and fast food outlets so it is important to detect S.aureus carriage among food handlers to prevent possible food contamination by them resulting in food poisoning.It also concluded that multiplex PCR is reliable and valuable method in detection of enterotoxigenic S.aureus strains and it is more sensitive and specific than SET-RPLA. This study recommended health education of food handlers to decrease contamination of their hands, settings training courses for food handlers to learn them the proper hand washing technique and frequent examination of food handler to find and treat. It also recommends screening food workers to identify staphylococcus aureas carriers and referring them to the appropriate health authorities for decolonization