Evaluation of antibiotic resistance and prevalence of common Salmonella enterica serovars isolated from foodborne outbreaks

Highlights

• Detection of common Salmonella enterica serovars using Multiplex PCR contributing national foodborne outbreaks.

• Detection Salmonellasenftenberg as one of predominant serovars and investigation of drug resistance.

• Isolation and investigation of drug resistance Paratyphi C.

Abstract

Salmonella is one of the major causes of foodborne outbreaks and numerous studies have reported the presence of its serovars in foodborne outbreaks. Identification of the most prevalent serovars, common polluted food types and attention to the antibiotic resistance of its serovars, are therefore key factors in the prevention and control of salmonellosis. The aim of this study is thus isolation of the common Salmonella serovars, identification of corresponding food categories and determination of their antibiotic resistance status in the stool samples of people poisoned in foodborne outbreaks in Iran during the period 2013 to 2019.

Salmonella strain was isolated with serotyping and antibiogram test on 1425 collected stools. among them, 83 samples (5.8%) contain salmonella strain .The most frequent serovars were S. enteritidisand S. senftenberg, respectively (26.3%, 21.3%). The highest salmonellosis incidence rates were observed in the consumption of cooked meat (64.2%) then fruits and vegetables (21.4%). According to our findings, an increase in the prevalence of Salmonella senftenberg in foodborne outbreaks with 5.3% resistance to extended spectrum cephalosporins such as ceftazidime and cefotaxime, and a decrease in cefepime sensitivity and nalidixic acid resistance could be warnings of the emergence of this serovar with increasing antibiotic resistance.

Introduction

Foodborne Salmonella enteric infection is the most prevalent cause of gastroenteritis around the world. The Institute for Health Metrics and Evaluation has listed typhoid and paratyphoid enteric infections as among the major causes of communicable diseases with significant global burden. Salmonella infections cause about 1.2 million cases of food poisoning, 23,000 cases of hospitalisation and about 450 deaths every year in the United States, as reported by the Center for Disease Control and Prevention (CDC) [1].

Several studies have been done of corresponding pathogens in foodborne outbreaks or endemic events around the world, and they reported various prevalence rates for different pathogens in different countries but, as it clear, Salmonella enterica spp are the dominant pathogens in these events, and their presence is independent of location, season and the primary health level of a country [2].

Salmonella enterica serovars cause a wide range of infections. They can induce severe gastric symptoms like enterocolitis, enteritis, systemic infection and gastroenteritis [3]. Gastroenteritis is the most frequent manifestation of Salmonella enterica infection, especially in the lower gastrointestinal tract.

Eight to 48 h after the ingestion of contaminated food or water, people suffer nausea, headache, abdominal cramp, vomiting and fever (38–39 °C; 100.5–102.2 °F). Diarrheal stools are usually non-bloody and of moderate volume, but large volumes of watery stools and dysentery may occur. Blood culture results are usually negative, but stool culture results are positive for 4–5 weeks after infection and, in rare cases of chronic carriage (<1%), for >1 year [4].

Salmonella Gastroenteritis is usually a self-limiting disease normally without antibiotic therapy, but two groups require medication including sensitive persons (children, elderlies) and immunocompromised patients such as the HIV-positive, diabetics or rheumatoid arthritis cases. Pre-emptive antibiotic treatment should be considered in these cases.

Treatment of patients with HIV/AIDS and NTS bacteraemia should have 1–2 weeks of IV antibiotic therapy followed by 4 weeks of oral therapy with a fluoroquinolone IV β-lactam antibiotic such as ceftriaxone or ampicillin for the patient's endocarditis or arteritis for 6 weeks, as recommended in Table 1 [5].

The major global problem in antibiotic therapy in gastric and other bacterial infections is antibiotic resistance. Various studies have been done of Salmonella enterica serovars’ antibiotic resistance in order to modify the treatment procedure. Resistance serovars and resistance level are different from country to country based on the available studies, so determination of resistant serovars in different areas is necessary to control infection transmission between and within societies. Primary health services, especially in food safety, are the same in many of regions in the world such as European countries but, in some areas like the Middle East, the coverage and level of food safety programmes is very unbalanced between countries. The incidence of Salmonella foodborne poisoning by more serovars of Salmonella is therefore possible, so the aims of this study are first, the determination of Salmonella serovars in Salmonella-positive patients from food poisoning events; second, the determination of Salmonella prevalence in food poisoning events; third, the determination of the most common transmitter foods; and fourth, the determination of the antibiotic resistance level of isolated Salmonella serovars to compare with other similar studies around the world.