Colistin (Polymyxin E) Use in Abdominal Solid Organ Transplant Recipients.

Background: Patients undergoing solid organ transplantation are at a higher risk of multi-drug resistant (MDR) bacterial infections especially during the immediate post operative period. Objective: To audit the usage, dosage appropriateness and safety of colistin use in abdominal solid organ transplant recipients to treat immediate post-transplant bacterial infections. Methods: After completion of 1000 abdominal solid organ transplants at our institute, data of the transplant recipients who received colistin between October 2010 and December 2019 was extracted from the hospital health information system. Data of all microbiological culture isolates, the minimum inhibitory concentration (MIC) of colistin, appropriateness of colistin dosing and nephrotoxicity associated with colistin use was assessed. Results: Of the 1170 (732 liver and 438 renal) solid organ transplant recipients, 82 (66 liver and 16 renal) received colistin to treat posttransplant MDR bacterial infections. Nearly 60% received colistin as definitive therapy and 87.81% received colistin as combination. Mean duration of colistin therapy was found to be higher in renal than liver transplant recipients. Out of the total 89 bacterial isolates, there were 2 colistin resistant Klebsiella strains. Colistin in combination with meropenem (36.4%) was the most commonly used dual therapy. Out of the total 89 bacterial isolates, there were 2 colistin resistant Klebsiella strains. Overall in-hospital mortality of patients who received colistin was 43.9%. Renal impairment occurred in 28.8% of liver transplant recipients. Conclusion: Infection necessitating colistin use increases mortality by three folds in liver transplant recipients and by five percentage points in renal transplant recipients.

Anti-infective properties of Lactobacillus fermentum against Staphylococcus aureus and Pseudomonas aeruginosa.

Surgical wounds and implant-associated Staphylococcus aureus and Pseudomonas aeruginosa infections are often difficult to treat because of limited susceptibility of several of these strains to conventional antibiotics. As a result, there is a constant need for new alternative drugs. The aim of this study was to investigate the antimicrobial properties of Lactobacillus fermentum, a probiotic bacterium, which we have isolated from colonic biopsies. The inhibition of S. aureus and P. aeruginosa growth was evaluated by coincubating with L. fermentum strains. Growth inhibition was tested for several of their clinical isolates using agar well diffusion assays. For biofilm assay S. aureus and P. aeruginosa were grown on the glass slides and in 96-well plates in presence of 2.5 µg/ml culture filtrate of L. fermentum. Biofilms were photographed using confocal microscope or stained with 0.1% crystal violet. Reduction in the cytotoxicity of S. aureus and P. aeruginosa was observed in presence of 2.5 µg/ml L. fermentum-spent media. Using in vitroexperiments, we showed that L. fermentum-secreted compound(s) inhibits the growth, cytotoxicity and biofilm formation of several S. aureus and P. aeruginosa strains. Compound(s) present in the culture supernatant of L. fermentum may have promising applications in treating hospital-acquired infections.

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study.

BACKGROUND: Gram-negative Enterobacteriaceae with resistance to carbapenem conferred by New Delhi metallo-beta-lactamase 1 (NDM-1) are potentially a major global health problem. We investigated the prevalence of NDM-1, in multidrug-resistant Enterobacteriaceae in India, Pakistan, and the UK. METHODS: Enterobacteriaceae isolates were studied from two major centres in India--Chennai (south India), Haryana (north India)--and those referred to the UK's national reference laboratory. Antibiotic susceptibilities were assessed, and the presence of the carbapenem resistance gene bla(NDM-1) was established by PCR. Isolates were typed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Plasmids were analysed by S1 nuclease digestion and PCR typing. Case data for UK patients were reviewed for evidence of travel and recent admission to hospitals in India or Pakistan. FINDINGS: We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries. INTERPRETATION: The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed.

Nuclear localization of flavivirus RNA synthesis in infected cells.

Flaviviral replication is believed to be exclusively cytoplasmic, occurring within virus-induced membrane-bound replication complexes in the host cytoplasm. Here we show that a significant proportion (20%) of the total RNA-dependent RNA polymerase (RdRp) activity from cells infected with West Nile virus, Japanese encephalitis virus (JEV), and dengue virus is resident within the nucleus. Consistent with this, the major replicase proteins NS3 and NS5 of JEV also localized within the nucleus. NS5 was found distributed throughout the nucleoplasm, but NS3 was present at sites of active flaviviral RNA synthesis, colocalizing with NS5, and visible as distinct foci along the inner periphery of the nucleus by confocal and immunoelectron microscopy. Both these viral replicase proteins were also present in the nuclear matrix, colocalizing with the peripheral lamina, and revealed a well-entrenched nuclear location for the viral replication complex. In keeping with this observation, antibodies to either NS3 or NS5 coimmunoprecipitated the other protein from isolated nuclei along with newly synthesized viral RNA. Taken together these data suggest an absolute requirement for both of the replicase proteins for nucleus-localized synthesis of flavivirus RNA. Thus, we conclusively demonstrate for the first time that the host cell nucleus functions as an additional site for the presence of functionally active flaviviral replicase complex.