Potentialization of β-lactams with colistin: in case of extended spectrum β-lactamase producing Escherichia coli strains isolated from children with urinary infections

Enhanced Antibacterial Activity of CuS-BSA/Lysozyme under Near Infrared Light Irradiation

The synthesis of multifunctional photothermal nanoagents for antibiotic loading and release remains a challenging task in nanomedicine. Herein, we investigated a simple, low-cost strategy for the preparation of CuS-BSA nanoparticles (NPs) loaded with a natural enzyme, lysozyme, as an antibacterial drug model under physiological conditions. The successful development of CuS-BSA NPs was confirmed by various characterization tools such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Lysozyme loading onto CuS-BSA NPs was evaluated by UV/vis absorption spectroscopy, Fourier-transform infrared spectroscopy (FTIR), zeta potential, and dynamic light scattering measurements. The CuS-BSA/lysozyme nanocomposite was investigated as an effective means for bacterial elimination of B. subtilis (Gram-positive) and E. coli (Gram-negative), owing to the combined photothermal heating performance of CuS-BSA and lysozyme release under 980 nm (0.7 W cm-2) illumination, which enhances the antibiotic action of the enzyme. Besides the photothermal properties, CuS-BSA/lysozyme nanocomposite possesses photodynamic activity induced by NIR illumination, which further improves its bacterial killing efficiency. The biocompatibility of CuS-BSA and CuS-BSA/Lysozyme was elicited in vitro on HeLa and U-87 MG cancer cell lines, and immortalized human hepatocyte (IHH) cell line. Considering these advantages, CuS-BSA NPs can be used as a suitable drug carrier and hold promise to overcome the limitations of traditional antibiotic therapy.

When Combined with Colistin, an Otherwise Ineffective Rifampicin-Linezolid Combination Becomes Active in Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii

The synergistic action of colistin, with two antibiotics active in Gram-positive bacteria but unable to kill gram negatives (linezolid and rifampicin), was investigated, since triple combinations are emerging as a tool to overtake multidrug resistance. Checkerboard determinations demonstrated that, when combined with colistin, the combination of linezolid and rifampicin turns active in multidrug-resistant Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Thus, the presence of sublethal concentrations of colistin resulted in a strongly synergistic interaction between these two drugs. Moreover, the minimum inhibitory concentrations of linezolid–rifampicin combinations in the presence of colistin were lower than the maximal concentrations of these antimicrobials ain blood. These findings suggest the use of this triple combination as an effective treatment of multidrug-resistant (MDR) bacterial infections.

Genetic diversity and antibiotic susceptibility of uropathogenic Escherichia coli isolates from kidney transplant recipients

Purpose

Uropathogenic Escherichia coli (UPEC) strains are a common cause of transplant rejection, morbidity, and mortality among kidney transplant recipients. The virulence of UPEC strains differs based on their pathogenicity islands (PAIs) and susceptibility to antibiotics. The present study evaluates the clonal relationship and antibiotic susceptibility of UPEC PAI-genotypes among Escherichia coli (E. coli) isolates from kidney transplant patients.

Patients and methods

A total of 115 Escherichia coli (E. coli) isolates were collected from kidney transplant recipients with acute urinary tract infections (UTIs). Isolates were typed based on the presence of PAI-markers, and random amplified polymorphic DNA (RAPD). The disk diffusion method was performed for the antibiotic susceptibility pattern of isolates.

Results

According to the PAI-specific virulence markers, 69 (60%), 21 (18.3%), and 25 (21.7%) isolates were identified as genotypes related to UPEC 536, UPEC J96, and UPEC CFT073 strains, respectively. PAI III536 genotypes were the most prevalent genotype in this study. The findings showed a high-sensitivity to imipenem (93.9%) and nitrofurantoin (91.3%) and a low-sensitivity to trimethoprim/sulfamethoxazole (36.5%). Clonal association and similar antibiotic susceptibility pattern were seen in the PAI-related genotypes.

Conclusion

Due to a similar pattern of antibiotic susceptibility of these clonal groups and increased resistance to some important antibiotics such as trimethoprim/sulfamethoxazole in the treatment of urinary tract infections, especially in kidney transplant patients, the spread of these clones should be considered as a serious concern.