In Bacillus subtilis LutR is part of the global complex regulatory network governing the adaptation to the transition from exponential growth to stationary phase

The lutR gene, encoding a product resembling a GntR-family transcriptional regulator, has previously been identified as a gene required for the production of the dipeptide antibiotic bacilysin in Bacillus subtilis. To understand the broader regulatory roles of LutR in B. subtilis, we studied the genome-wide effects of a lutR null mutation by combining transcriptional profiling studies using DNA microarrays, reverse transcription quantitative PCR, lacZ fusion analyses and gel mobility shift assays. We report that 65 transcriptional units corresponding to 23 monocistronic units and 42 operons show altered expression levels in lutR mutant cells, as compared with lutR+ wild-type cells in early stationary phase. Among these, 11 single genes and 25 operons are likely to be under direct control of LutR. The products of these genes are involved in a variety of physiological processes associated with the onset of stationary phase in B. subtilis, including degradative enzyme production, antibiotic production and resistance, carbohydrate utilization and transport, nitrogen metabolism, phosphate uptake, fatty acid and phospholipid biosynthesis, protein synthesis and translocation, cell-wall metabolism, energy production, transfer of mobile genetic elements, induction of phage-related genes, sporulation, delay of sporulation and cannibalism, and biofilm formation. Furthermore, an electrophoretic mobility shift assay performed in the presence of both SinR and LutR revealed a close overlap between the LutR and SinR targets. Our data also revealed a significant overlap with the AbrB regulon. Together, these findings reveal that LutR is part of the global complex, interconnected regulatory systems governing adaptation of bacteria to the transition from exponential growth to stationary phase.

Microorganisms isolated from the bile of the patients who have undergone cholecystectomy and their antibiotic resistance pattern: multicenter prospective study

Background Gallbladder and biliary tract infections are diseases with high mortality rates if they are not treated properly. Microbiological evaluation of perioperatively collected samples both ensures proper treatment of patients and guides empirical treatment due to the determination of microorganism susceptibility. Aims This study aimed to isolate the microorganisms in bile cultures from patients who underwent cholecystectomy and to determine sensitivity results of these microorganisms. Methods This study was a multi-center and prospective design, included 360 patients, and was performed between 2019 and 2020. Culture results of bile taken during cholecystectomy were evaluated. Results Bacterial growth was found in the bile cultures of 84 out of 360 (23.3%) patients. Patients were divided into two groups according to whether they had risk factors for resistant microorganisms or not. While Escherichia coli (n=11, 13%), Enterococcus spp. (n=8, 9.5%), and Enterobacter spp. (n=4, 4.7%) were detected most frequently in patients without risk. Staphylococcus spp. (n=17, 20.2%), Enterococcus spp. (n=16, 19%), and E. coli (n=8, 9.5%) were the most frequently found microorganism at-risk patients. In multivariate analysis, bile culture positivity was found higher in patients who had history of biliary disease (p=0.004), operation performed concurrently with a cholecystectomy (p=0.035), and high rate of polymorphonuclear leukocytes (PNL) in total leukocyte count (p=0.001). Conclusions Our study shows that when starting empirical antibiotic treatment for bile ducts, whether patients are at risk for the development of resistant bacterial infection should be evaluated after which antibiotic selection should be made accordingly