Uropathogenic E.coli (UPEC) are among major pathogens causing urinary tract infections. Virulence factors are mainly responsible for the severity of these emerging infections. This study was planned to investigate the distribution of virulence genes and cytotoxic effects of UPEC isolates with reference to phylogenetic groups (B2, B1, D and A) to understand the presence and impact of virulence factors in the severity of infection in Faisalabad region of Pakistan.

The pathogenesis of Salmonella enterica serovar Typhi (S. Typhi), the cause of typhoid fever in humans, is mainly attributed to the acquisition of horizontally acquired DNA elements. Salmonella pathogenicity islands (SPIs) are indubitably the most important form of horizontally acquired DNA with respect to pathogenesis of this bacterium. The insertion or deletion of any of these transferrable SPIs may have impact on the virulence potential of S. Typhi. In this study, the virulence potential and genetic relatedness of 35 S. Typhi isolates, collected from 2004 to 2013 was determined by identification of SPI and non-SPI virulence factors through a combination of techniques including virulotyping, Whole Genome Sequencing (WGS), and Variable Number of Tandem Repeats (VNTR) profiling. In order to determine the virulence potential of local S. Typhi isolates, 56 virulence related genes were studied by PCR. These genes are located in the core as well as accessory genome (SPIs and plasmid). Major variations among studied virulence determinants were found in case of SPI-7 and SPI-10 associated genes. On the basis of presence of virulence related genes, the studied S. Typhi isolates from Pakistan were clustered into two virulotypes Vi-positive and Vi-negative. Interestingly, SPI-7 and SPI-10 were collectively absent or present in Vi-negative and Vi-positive strains, respectively. Two Vi-negative and 11 Vi-positive S. Typhi strains were also analyzed by whole genome sequencing (WGS) and their results supported the PCR results. Genetic diversity was tested by VNTR-based molecular typing. All 35 isolates were clustered into five groups. Overall, all Vi-negative isolates were placed in a single group (T5) whereas Vi-positive isolates were grouped into four types. Vi-negative and Vi-positive isolates were mutually exclusive. This is the first report on the comparative distribution of SPI and non-SPI related virulence genes in Vi-negative and Vi-positive S. Typhi isolates with an important finding that SPI-10 is absent in all Vi-negative isolates. The distribution of virulence factors in S. Typhi can vary in isolates from different geographical regions and can have significant effect on the disease control. In this study, we have checked the distribution of 56 reported virulence associated factors in 35 local isolates of S. Typhi to identify any variations that can help in designing effective control strategies for typhoid. We have identified four naturally occurring variants which are simultaneously lacking SPI-7 and SPI-10, two adjacently located pathogenicity islands on S. Typhi chromosome. These isolates are not producing Vi capsular antigen hence the Vi based vaccines will not be effective against them. These findings highlight the need to develop typhoid vaccines specifically effective in Pakistan.

Rapid emergence of resistance in Salmonella enterica serovar Typhi ( Salmonella Typhi) against most of the available therapeutic options for typhoid has rendered its treatment more difficult. This study sought to determine the current scenario of antimicrobial resistance in local isolates of Faisalabad following several treatment failure reports. Out of 300 clinical specimens collected in 2018, 45 isolates were identified as Salmonella Typhi. To assess changes, we compared their antibiogram profile with 31 Salmonella Typhi strains isolated in 2005. The isolates collected during 2018 showed a significant rise in antimicrobial drug resistance as compared with isolates revived from the cultures of 2005, including 15 multidrug-resistant (MDR), 20 extensively drug-resistant, and 14 pan drug-resistant isolates compared with only 8 MDRs from 2005. Notably, in 2018 isolates, resistance to azithromycin was seen in 75% of the isolates. Extended-spectrum beta-lactamase production was detected in 47% of Salmonella Typhi isolates and 18% isolates showed resistance against carbapenems. The sequences of two carbapenemase genes, VIM and GES, found in Salmonella Typhi were submitted in NCBI. The carbapenem resistance is rare in Enterobacteriaceae and probably first time reported in Salmonella Typhi. H58 haplotype was identified in the 2018 Salmonella Typhi isolates and PCR–restriction fragment length polymorphism method identified 16.7% of H58 strains that belonged to lineage I, 19.4% of H58 strains that belonged to lineage II, and the remaining 63.9% that belonged to the node. The regional difference in the antimicrobial resistance trend needs effective epidemiological studies.