Plasmid-mediated AmpC in Klebsiella pneumoniae and Escherichia coli from septicaemic neonates: diversity, transmission and phenotypic detection.

OBJECTIVES: Presence and dissemination of plasmid-mediated AmpC genes (pAmpCs) have made bacteria cephalosporin-resistant and assessment of their prevalence and diversity is essential. Coexistence of pAmpCs with New Delhi metallo-ß-lactamase (blaNDM) has facilitated their spread and NDM interferes with correct pAmpC phenotypic identification. METHODS: Assessment of pAmpCs in different species and sequence types (STs), co-transmission with blaNDM and phenotypic detection were analysed among Klebsiella pneumoniae (n = 256) and Escherichia coli (n = 92) isolated from septicaemic neonates over 13 years. RESULTS: pAmpCs were present in 9% (30/348) of strains, 5% in K. pneumoniae and 18% in E. coli. pAmpC genes (blaCMY and blaDHA) were detected, blaCMY-42 and blaDHA-1 variants being predominant. Strains were resistant to most antimicrobials tested. blaCMY and blaDHA were dominant among E. coli (14/17) and K. pneumoniae (9/13), respectively. pAmpC-bearing strains belonged to diverse STs, including epidemic K. pneumoniae ST11 and ST147. Some strains co-harboured carbapenemase genes, blaNDM (17/30) and blaOXA-48 (5/30). In 40% (12/30) of strains, pAmpC genes were transferred by conjugation, of which 8/12 exhibited co-transfer with blaNDM. pAmpCs were frequently found in replicons as follows: blaDHA-1 with IncHIB-M, blaCMY-4 with IncA/C, blaCMY-6 with IncA/C, and blaCMY-42 with IncFII. The combination disk-diffusion test correctly detected pAmpC in 77% (23/30) of pAmpC-bearing strains. However, correct detection of pAmpC was higher in strains that did not harbour blaNDM vs. those with blaNDM (85% vs. 71%). CONCLUSION: Presence of pAmpCs along with carbapenemases, linkage with multiple STs, and replicon types indicated their potential for spread. pAmpCs can go undetected in the presence of blaNDM; hence, regular surveillance is required.

Effect of vasodilator and immunosuppressive therapy on the endothelial dysfunction in patients with systemic sclerosis.

A comparative analysis of flow-mediated vasodilation (FMD), vasoactive angiogenic, and fibrogenic mediators between treatment-naive and treated systemic sclerosis (SSc) patients is an unmet need. (1)To assess the FMD and different pathogenic mediators in SSc patients about endothelial dysfunction. (2) To assess the proportion of circulating endothelial cells (CECs) in treatment-naïve patients. SSc patients were grouped into treatment-naïve (Group-I, n = 24) on vasodilator (Group-II, n = 10), on vasodilator + immunosuppressive (Group-III, n = 22)]. Age-sex matched healthy controls (n = 20) were included. Endothelial dysfunction (ED) was measured radiologically using FMD. Serum levels of NO, ET1, NO/ET1, sVCAM, sICAM, TGF, IL-6, and VEGF, as well as gene expressions of eNOS, iNOS, ET-1, and TGF, were measured to assess the status of ED in various study groups. CEC was measured in Group-I and HC. CEC was used as a marker to identify a key regulator of ED in SSc. FMD was significantly decreased in all SSc patients through receiving treatment. Upregulation of serum NO and ET concentrations was noted post-treatment with an unaltered NO/ET1 ratio. NO was positively correlated with FMD (r = 0.6) and negatively with TGFß (r = - 0.5). ET-1 showed a negative correlation with TGFß (r = - 0.5) but no significant correlation with FMD. Circulating endothelial cell (CEC) was significantly higher in Group-I (3.2%) than HC (0.8%) (p = 0.002), and it showed a good correlation with NO (r = - 0.7, p = 0.0001) and NO/ET1 (r = - 0.6, p = 0.007). Persistent ED was observed in all SSc patients irrespective of treatment. Dysbalance in NO/ET1 ratio might be the considering factor for the underlying progression of ED. Based on our findings, it may be hypothesized that reduced NO may be a contributing factor in the pathogenesis of endothelial dysfunction in SSc.

CRISPR-Cas system, antibiotic resistance and virulence in bacteria: Through a common lens.

CRISPR-Cas system, antibiotic resistance and virulence are different modes of survival for the bacteria. CRISPR-Cas is an adaptive immune system that can degrade foreign DNA, antibiotic resistance helps bacteria to evade drugs that can threaten their existence and virulence determinants are offensive tools that can facilitate the establishment of infection by pathogens. This chapter focuses on these three aspects, providing insights about the CRISPR system and resistance mechanisms in brief, followed by understanding the synergistic or antagonistic relationship of resistance and virulence determinants in connection to the CRISPR system. We have addressed the discussion of this evolving topic through specific examples and studies. Different approaches for successful detection of this unique defense system in bacteria and various applications of the CRISPR-Cas systems to show how it can be harnessed to tackle the increasing problem of antibiotic resistance have been put forth. World Health Organization has declared antibiotic resistance as a serious global problem of the 21st century. As antibiotic-resistant bacteria increase their footprint across the globe, newer tools such as the CRISPR-Cas system hold immense promise to tackle this problem.