Features of Proteus mirabilis clinical isolates and genetic relations inside the group

Proteus mirabilis, a bacterium causing urinary tract infections and exhibiting multidrug resistance, poses challenges in treatment and infection control. Molecular typing methods aid in understanding genetic diversity and relationships among isolates. Repetitive Intergenic Consensus ERIC-PCR and Random Amplified Polymorphic DNA (RAPD) are considered some of the rapid and simple genetic tests. The aim of the current study was to determine the differential ability of RAPD and ERIC-PCR in biotyping P. mirabilis isolated from clinical samples. This study was conducted in Al-Diwaniyah Governorate, Iraq, between 2023 and 2024. A total of 189 samples were collected from wounds, burns, stools, and urine from patients hospitalized in several hospitals in the city of Diwaniyah (Iraq). From these samples, twenty isolates of P. mirabilis were isolated and initially diagnosed using biochemical tests. Then the diagnosis was confirmed using the VITEK system 2. Bacterial resistance to antibiotics was assessed using the VITEK system 2, then an examination of the bacteria's ability to produce biofilm was performed, following which the genomic DNA was extracted from the bacteria, and the ERIC and RAPD tests were performed. The differential ability of RAPD and ERIC-PCR was evaluated based on the Simpson's Index of Diversity (SID). The results revealed high multidrug resistance prevalence (55%) while a smaller number of isolates displayed resistance to either one (15%) or two (25%) antibiotic classes. There was only one susceptible isolate (5%). Biofilm-forming capabilities showed negative biofilm formation (30%), weakened positive (25%), moderate positive (30%), finally strong positive was exhibited in 3 isolates (15%). ERIC-PCR demonstrated high differentiation ability between bacterial isolates in the current study compared to RAPD-PCR. Notably, significant associations were found between biofilm formation categories with ERIC-PCR clusters, and between sample sources with ERIC-PCR clusters. This highlights ERIC-PCR's potential for epidemiological investigations and infection control of P. mirabilis.