Prevalence of Biofilm Formation in Salmonella typhi Isolated from Enteritis Patients in Al-Najaf-Iraq

Several types of bacteria enhance their survival by attaching to non-living surfaces or tissues, presenting them as multicellular communities covered by a protective extracellular matrix called biofilm. There has been a clear interest in assessing the relationship between antibiotic resistance phenotype and biofilm production. The aim of this paper was to present additional experimental results on this topic and to test the ability of Salmonella typhi isolates to biofilm formation using in vitro methods in the context of their antibiotic resistance. In the result of the study, 28 isolates of S. typhi were included. All 28 clinical specimens 100% showed strong biofilm formation and all clinical specimens showed the presence of pml gene by clear bands in gel electrophoresis. The results of the antibiotic sensitivity test of S. typhi isolates by disk diffusion method against 18 types of commonly used antibiotics showed a large variation in their rates of antibiotic resistance, as the highest percentage of resistance to the antibiotic to S. typhi resistance to the most common antibiotics used in treatment. The highest rate of resistance was seen with Ciprofloxacin and Gentamycin, Ceftrazidime, Cefotaxime, Amoxicillin, Ampicillin 28/28 (100%) followed by Azithromycin and Cephalothin 26/28 (92.9%), Levofloxacin and Erythromycin 22/28 (78.6%), Chloramphenicol 20/28 (71.4%), Clindamycin 8/28 (28.6%), Imipenem 4/28 (14.3%), Tobramycin, Netilmicin and Tetracycline 3/28 (10.7%) as all isolates were sensitive. The study found a positive correlation between interesting study genes and biofilm formation and antibiotics in S. typhi. Strains that appeared multidrug-resistant (MDR) were given a high mean of biofilm. It has been demonstrated that some correlations exist between antibiotic resistance and the biofilm-forming ability of S. typhi isolates. There is an association between biofilm production with persistent infection and antibiotic failure.