Molecular characterization of Pseudomonas aeruginosa isolates from various clinical specimens in Khartoum/Sudan: Antimicrobial resistance and virulence genes

Background: Pseudomonas aeruginosa is a pathogenic organism responsible for frequent wound and nosocomial infections worldwide. Its infections are difficult to control since the organism is known to rapidly develop antibiotic resistance and becomes multidrug-resistant (MDR) during treatment of patients. Aim of the study: This study was intended to investigate the occurrence of certain important types of (ESBL) and (MBL) enzymes in association with important specific virulence factors  associated with P. aeruginosa clinical isolates from Khartoum, Sudan. Methods: This study investigated 70 P. aeruginosa isolates which were collected from patients admitted to four major hospitals in Khartoum  (Fedail, Ribat, Ibn Sina and Soba hospitals). These isolates were recovered from 40 wound swabs (57.1%), 27 urine samples (38.6%), and 3 pleural fluid samples (4.3%) of patients. Higher numbers of isolates were recovered from males 42 (60%) than in females 28 (40%). All P. aeruginosa isolates were first confirmed by conventional biochemical and second using molecular PCR tests.   PCR methods were also used for detecting the presence of the virulence genes ToxA, AlgD, LasB, exoS, exoU, CTX, GES-1, and genes of VIM, IMP, KPC, CTX, VEB-1 and SHV-1. Results:   Antimicrobial susceptibility testing of P. aeruginosa isolates showed a high resistance to azetronam 49 (70%), followed by ceftazidime 32 (45.7%), 16 ciprofloxacin (22.9%), gentamicin 13 (18.6 %), piperacillin-tazobactam 11 (15.7%), amikacin 9 (12.9 %), and imipenem 6 (8.6%) showed the least resistance. All isolates were positive for algD and lasB (100%), followed by toxA (90%), exoS (34.3), exoU (24.3%), respectively. The rates of detected ESBL genes blaTEM, blaCTX-m, blaSHV-1,GES-1, were 3.3%, 6.6%, 10%, 3.3%,10%, respectively, but all isolates were negative for bla-KPC and bla- VIM and IMP . The percentages of pigment production were 61.4% for pyocyanin, 37.1% for pyoverdin and 1.4% for pyorubin. Conclusion: The study demonstrated high rates of antimicrobial resistance markers to most commonly used antibiotics in treatment of P. aeruginosa infections. The majority of the isolates from urine and wound samples carried at least three potential virulence factor genes of algD, lasB and toxA and without any significant relation to their antimicrobial resistance markers. &nbsp

A novel role in cytokinesis reveals a housekeeping function for the unfolded protein response

The unfolded protein response (UPR) pathway helps cells cope with endoplasmic reticulum (ER) stress by activating genes that increase the ER's functional capabilities. We have identified a novel role for the UPR pathway in facilitating budding yeast cytokinesis. Although other cell cycle events are unaffected by conditions that disrupt ER function, cytokinesis is sensitive to these conditions. Moreover, efficient cytokinesis requires the UPR pathway even during unstressed growth conditions. UPR-deficient cells are defective in cytokinesis, and cytokinesis mutants activate the UPR. The UPR likely achieves its role in cytokinesis by sensing small changes in ER load and making according changes in ER capacity. We propose that cytokinesis is one of many cellular events that require a subtle increase in ER function and that the UPR pathway has a previously uncharacterized housekeeping role in maintaining ER plasticity during normal cell growth

The chromatin remodeler ISW1 is a quality control factor that surveys nuclear mRNP biogenesis

Chromatin dynamics play an essential role in regulating DNA transaction processes, but it is unclear whether transcription-associated chromatin modifications control the mRNA ribonucleoparticles (mRNPs) pipeline from synthesis to nuclear exit. Here, we identify the yeast ISW1 chromatin remodeling complex as an unanticipated mRNP nuclear export surveillance factor that retains export-incompetent transcripts near their transcription site. This tethering activity of ISW1 requires chromatin binding and is independent of nucleosome sliding activity or changes in RNA polymerase II processivity. Combination of in vivo UV-crosslinking and genome-wide RNA immunoprecipitation assays show that Isw1 and its cofactors interact directly with premature mRNPs. Our results highlight that the concerted action of Isw1 and the nuclear exosome ensures accurate surveillance mechanism that proofreads the efficiency of mRNA biogenesis

Delayed Ras/PKA signaling augments the unfolded protein response

During environmental, developmental, or genetic stress, the cell’s folding capacity can become overwhelmed, and misfolded proteins can accumulate in all cell compartments. Eukaryotes evolved the unfolded protein response (UPR) to counteract proteotoxic stress in the endoplasmic reticulum (ER). Although the UPR is vital to restoring homeostasis to protein folding in the ER, it has become evident that the response to ER stress is not limited to the UPR. Here, we used engineered orthogonal UPR induction, deep mRNA sequencing, and dynamic flow cytometry to dissect the cell’s response to ER stress comprehensively. We show that budding yeast augments the UPR with time-delayed Ras/PKA signaling. This second wave of transcriptional dynamics is independent of the UPR and is necessary for fitness in the presence of ER stress, partially due to a reduction in general protein synthesis. This Ras/PKA-mediated effect functionally mimics other mechanisms, such as translational control by PKR-like ER kinase (PERK) and regulated inositol-requiring enzyme 1 (IRE1)-dependent mRNA decay (RIDD), which reduce the load of proteins entering the ER in response to ER stress in metazoan cells