tcpC as a prospective new virulence marker in blood Escherichia coli isolates from sepsis patients admitted to the intensive care unit

Phenotypic and genotypic evaluation of aminoglycoside resistance in Escherichia coli isolated from patients with blood stream infections in Tehran, Iran

Background and Objectives

Escherichia coli is a significant causative agent of bloodstream infections (BSIs). Aminoglycoside antibiotics play a crucial role in treating severe infections such as sepsis and pneumonia. However, resistance to these antibiotics often occurs due to the production of aminoglycoside-modifying enzymes (AMEs). This study was conducted to assess antimicrobial susceptibility patterns against various aminoglycosides and to determine the prevalence of common AME genes in E. coli strains isolated from BSIs.

Materials and Methods

Sixty-five E. coli isolates were obtained from blood samples in a referral hospital in Tehran, Iran. The susceptibility patterns of aminoglycosides were determined using disk diffusion method and AMEs genes were investigated using PCR assay.

Results

Resistance to aminoglycosides was observed in 64.6% (42/65) of the isolates. The most frequent resistance rate was found for kanamycin (44.6%) and gentamicin (38.5%), followed by tobramycin (29.2%) and amikacin (4.6%). The most frequent AME gene was aac(3)-IVa, which detected in 49.2% isolates, followed by aac(6)-Ib (40%), aac(3)-IIa (32.3%), and ant(2)-Ia (30.8%), respectively.

Conclusion

Athough the findings of this survey are based on specimens collected from a single hospital, our study shows that the high prevalence of aminoglycoside resistance is primarily attributed to the presence of the aac(3)-Iva, aac(6)-Ib and aac(3)-IIa genes. The low rate of resistance to amikacin makes this antibiotic a good candidate for treatment of BSIs due to E. coli.

The diet-microbiota axis: a key regulator of intestinal permeability in human health and disease

The intestinal barrier orchestrates selective permeability to nutrients and metabolites while excluding noxious stimuli. Recent scientific advances establishing a causal role for the gut microbiota in human health outcomes have generated a resurgent interest toward intestinal permeability. Considering the well-established role of the gut barrier in protection against foreign antigens, there is mounting evidence for a causal link between gut permeability and the microbiome in regulating human health. However, an understanding of the dynamic host-microbiota interactions that govern intestinal barrier functions remains poorly defined. Furthermore, the system-level mechanisms by which microbiome-targeted therapies, such as probiotics and prebiotics, simultaneously promote intestinal barrier function and host health remain an area of active investigation. This review summarizes the recent advances in understanding the dynamics of intestinal permeability in human health and its integration with gut microbiota. We further summarize mechanisms by which probiotics/prebiotics influence the gut microbiota and intestinal barrier functions.

The relation of phylogroups, serogroups, virulence factors and resistance pattern of Escherichia coli isolated from children with septicemia

The characterization of virulent and drug-resistant Escherichia coli strains helps to control and provide more accurate information regarding infection and eradication. The aim of this study was to determine the relationship between antibiotic susceptibility, phylogroups and virulence factors of E. coli isolates from children with septicaemia. One hundred dereplicated E. coli isolates were collected from paediatric patients with septicaemia in five hospitals in Tehran (May 2015 to May 2018). The antibiotic susceptibility of isolates was performed as per the 2016 guidelines of the Clinical and Laboratory Standards Institute. Extended-spectrum β-lactamases and carbapenemase genes, phylogroups, serogroups and virulence encoding genes were detected by PCR. Phylogroup B2 was dominant (40%) among strains, followed by phylogroups D (30%), A (8%) and B1 (7%). CTX-M1 was significantly higher in the B2 group (n = 21, p 0.001). Furthermore, the virulence genes iutA (n = 27, p 0.002), csgA (n = 39, p <0.001), kpsMII (n = 39, p 0.002), ibeA (n = 4, p 0.004), vat (n = 5, p 0.003), traT (n = 24, p <0.001), sat (n = 12, p 0.001) and hlyA (n = 33, p <0.001) showed significantly higher rates in phylogroup B2. Three O25/CTXM1/OXA-48 and cnf, iutA, csgA and traT positive isolates belonged to phylogroup B2. Pulsed-field gel electrophoresis analysis showed 85% similarity among 25% of isolates. More than half of the isolates were multidrug-resistant E. coli. A significant relation was observed among iutA, csgA, kpsMII, ibeA, vat, traT, sat and hlyA genes and phylogroup B2. The characterization of virulent and drug-resistant strains helps control and properly eliminate infections. There was no genetic relation among strains in the pulsed-field gel electrophoresis pattern.