Role of gallstones in typhoid carriage in Egyptian patients

Objectives: Salmonella typhi forms biofilm on the surface of gallstones promoting colonization and carrier state. Theaims are to detect its frequency in chronic calcular cholecystitis patients, to find out their antibiotic resistance pattern,and also to examine biofilm on the surface of gallstones and detect its correlation to antibiotic susceptibility pattern.Materials and methods: The study group included 257 patients with chronic calcular cholecystitis. S. typhi was isolatedfrom gall bladder specimens. Antibiotics susceptibility tests of the isolates were done. Biofilm on surface of gallstoneswere visualized using scanning electron microscopy. Virulence (Vi) antibodies against S. typhi were studied in sera of257 healthy controls.Results: 10.9% of patients were chronic typhoid carriers compared to only 3.5% of the controls (OR= 3.37, p=0.002).Multidrug resistance was detected in 35.7% of isolates. S. typhi biofilms on the surface of the 21/28 (75%) gallstoneswere detected. Ninety percent of the strains that produced maximum amount of biofilm were multidrug-resistant.Conclusion: Chronic calcular cholecystitis patients are more prone to typhoid carriage due to biofilm formation of S.typhi on the surface of gallstones. J Microbiol Infect Dis 2012; 2(4): 142-149Key words: Gall bladder, Chronic calcular cholecystitis, Salmonella typhi, biofilm, antibiotic resistance