Study design and period
A cross sectional study was conducted among food handlers at Wolkite University cafeteria, Southern Ethiopia from December, 2016 to February, 2017. At that time, the cafeteria had 340 food handling personnel (301 females and 39 males) serving for about 11,000 students.
Sampling size determination and sampling techniques
Sample size was determined using single population proportion formula taking the prevalence of Salmonella species as 6.9% from previous study , confidence level of 95%, 4% margin of error and with the assumption of 10% non response rate. Thus, the final sample size became 170.
All food handlers from the University food handling establishments were considered and divided into four groups based on their job description as cookers, servers, cleaners and choppers. Then, the total sample size was allocated to each group based on probability proportional to size sampling technique. Accordingly, 68 cookers, 49 servers, 30 cleaners and 23 choppers were selected by using simple random sampling method. Food handlers who were symptomatic, those who had taken antibiotics, anti-helminthes within three weeks prior to the study and newly recruited food handlers were excluded from the current study.
Data collection procedures
Personal data, hygienic profile, knowledge and attitude assessments were collected by face to face interview using structured questionnaire adopted from similar survey and literatures.
Ova/parasite detection: A stool sample was collected from each food handler using sterile stool cup and a loop full used for wet mount. Intestinal parasites were examined and identified by direct microscopic examination of wet stool preparations, with a small amount of the respective stool sample emulsified in a drop of physiological saline, iodine solution and formol-ether concentration sedimentation techniques as per the standards. The parasites identified in any one of the three techniques from a single specimen were reported as positive .
Culturing of Salmonella and Shigella Species: Stool samples were cultured in appropriate culture media (Oxoid, UK) for bacteriological investigations. Stool specimens were pre-enriched with Selenite F broth and inoculated to Xylose Lysine Deoxycholate (XLD) by incubating at 37°C for 24 hours for isolation of Shigella and Salmonella isolates. Colony characteristics and biochemical tests were applied to differentiate entero-pathogens, glucose and lactose fermentation, hydrogen sulfide production, Kliger iron agar, indole, Simon’s citrate agar, lysine iron agar, urea, and motility . To differentiate from other enterobacterceae and as a confirmatory test, we have used API-20E (Biomerieux, France).
Antibiotic susceptibility was performed by Kirby-Bauer disc diffusion on Muller-Hinton agar using Norfloxacillin (10μg), Gentamicin (10μg), Ceftriaxone (30μg), Ciprofloxacin (5μg), Tetracycline (30μg), Chloramphenicol (30µg) and Trimethoprim-Sulphamethoxazole (25μg). The reading and interpretation of the results as sensitive, intermediate, and resistant were conducted in reference to CLSI, 2015 .
Quality Control: Standard operating procedures (SOPs) were strictly followed during laboratory specimen’s collection, processing and culturing. American type culture collection bacterial reference strain of Escherichia coli ATCC25922 was used as a quality control for antibiotic susceptibility testing.
The data were edited, coded, and entered into SPSS version 20 statistical software. Descriptive statistics were used to determine frequencies and percentages. The relationship between variables was computed using chi-square and p-value less than 0.05 was considered as statistically significant.