In this study, the prevalence of Salmonella among food handlers was 22 (7.3%). This was similar to studies carried out in Southern Ethiopia, Arba Minch University (6.9%) , and Nigeria, Abeokuta (5.5%) . However, it was higher than the studies reported from Ethiopia, Addis Ababa (3.5%) , Bahir Dar (1.6%) , and Gondar (3.1%) . On the other hand, our result was lower than the studies reported from Ethiopia, Addis Ababa (10.5%) , and Nigeria (42.3%) . The variation might be attributed to poor personal hygiene and environmental sanitation differences among the study areas.
The prevalence of Shigella (3.7%) in our study is consistent with studies done in Southern Ethiopia, Arba Minch University (3%) , Ethiopia, Addis Ababa (4.5%) , and Gondar (3.1%) . However, our finding was lower than a study conducted in Nigeria (15.5%) . These might be due to the differences in inconsistent training on food preparation and handling and hygiene practices of the food handlers.
In the present study, not practicing handwashing after using the bathroom among food handlers was significantly associated with Salmonella and Shigella carriers. Food handlers who hadn’t washed their hands after using the bathroom were more likely to be colonized with Salmonella and Shigella compared to those who washed with water and soap after using the bathroom. This finding was similar to a study conducted in Ethiopia, Mekelle , Gondar , and Bahir Dar . The acquisition of Salmonella and Shigella is due to poor sanitary conditions, poor toilet facilities, and scarcity of availability of facilities used for handwashing practice. A majority of food handlers of the university reported that they washed their hands with only water and some of them not wash their hands neither with water only nor with soap and water after the bathroom.
Our finding also revealed that there is a statistically significant difference in handwashing after touching dirty materials among food handlers with Salmonella and Shigella carriers. Food handlers who did not wash their hands after touching dirty materials are twenty-eight fold more likely to be colonized with Salmonella and Shigella than those who washed with water and soap after touching dirty materials. This finding is consistent with a study conducted in Ethiopia, Bahir Dar . This might be due to the absence of handwashing facilities within proximity of the food handler’s workplace.
Our study showed that food handlers who washed their hand with soap and water before touching food were less likely to be colonized with Salmonella and Shigella than food handlers who did not wash their hand with soap and water before food preparation. This is in line with the finding of a similar study reported from Ethiopia, Yebu Town . In the majority of food handlers, handwashing before handling food was practiced. However, a very large proportion (42.8%) washed their hands only with water. There are food handlers who apply some hygiene practice, though many of them do not use soap nor do they appreciate or understand the need for handwashing .
Furthermore, in this finding, untrimmed fingernail was significantly associated with Salmonella and Shigella colonization among food handlers. This study is similar to studies conducted in Ethiopia, Yebu Town , and Arba Minch . This result might be due to the lifestyle of food handlers. Examination of fingernail contents of food handlers for Salmonella or Shigella is one way of indicating a source of possible food contamination . However, the current study did not assess the Salmonella and Shigella carriage of fingernail contents.
Salmonella and Shigella carriers who are preparing and handling food daily can act as
sources of infection to the community the university via the food chain. Therefore, regular training, medical check-up programs and accessibility of personal hygiene guidelines with intensive health education could be important to prevent and control the carriage.
Antimicrobial susceptibility pattern data showed that ciprofloxacin, ceftriaxone, gentamicin, chloramphenicol, and cotrimoxazole were effective against the Shigella isolates. Our finding was comparable with studies reported from Ethiopia, Haramaya University on ceftriaxone (16.7%) , Jimma on gentamicin (1.3%) , and Harar on gentamicin (3.6%) . Whereas our result showed lower resistance patterns compared to the studies conducted in Ethiopia, Addis Ababa on gentamicin (75.6%) , and Gondar on ciprofloxacin (8.9%) and cotrimoxazole (73.4%) [37,38]. This increase of resistance from those reports indicates that there are differences in the geographical area, study period and study design. Increased resistance was observed in our finding which is in line with a study reported from Harar on ampicillin (100%) , Arba Minchon amoxicillin (100%) .
In the current study, isolates of Salmonella species were sensitive to gentamicin, ciprofloxacin, chloramphenicol, ceftriaxone, cotrimoxazole, and clarithromycin. This is consistent with reports from Gondar University, Ethiopia[24, 25, 38]. Increased resistance was observed in our findings for amoxicillin-clavulanic, amoxicillin, and ampicillin which were supported by studies reported from Ethiopia, Arba Minch, Jimma, and Bahir Dar [14,12,23,35]. This might be due to misuse or inappropriate use of antibiotics and the use of clinical diagnosis for treatment by physicians may lead to emerging of drug-resistant bacterial strains and replacement of sensitive strains by resistant strains.
The prevalence of multidrug resistance towards Salmonella and Shigella were observed. Out of all the isolates, 54.54% Salmonella and 90.9 % Shigella species were resistant to at least three antimicrobials. One isolate of Shigella was resistant to six classes of antimicrobial agents. This study is supported by a study conducted in Ethiopia Butajira , Addis Ababa , Haramaya University , and Gondar . This increased multidrug resistance might be due to genetic variation by mutations, irrational use of antimicrobials, and less hygienic practice of the food handlers. Salmonella and Shigella species are becoming resistant to most antimicrobials, indicates that there might be easy availability, irrational use common antimicrobials from different governmental and private pharmacies.
Fingernail content examination could not be identified. This may be supportive to know either the contamination is due to poor fingernail hygiene or poor food handling practices. Despite this limitation, the methods used to isolate and characterize the antimicrobial susceptibility pattern of Salmonella and Shigella spp. are comprehensive. In the current study, because of the self-reported nature of the study, recall bias was a limitation but it is not reflected in the findings. We also do not know what biases have the greatest impact on self-reports. In addition to that, even though this study used a random sampling technique to select study participant’s it was facility-based. Then Hosmer-Lemeshow test is used for overall calibration error but not used for a particular lack of fitness, so it does not properly take overfitting into account. Therefore generalizability might be hardly achieved. Additionally, Since there is variation in seasons, geography, and in the definition of antimicrobial resistance guidelines among different studies and across regions we couldn’t infer the external validity.