Introduction: Increased carbapenem resistance in Klebsiella spp. strains causes high morbidity and mortality. The genes encoded for carbapenemaseare transferrable between different bacterial species. In the present study, we aimed to investigate carbapenem resistance genes in Klebsiella spp. strains. Methodology: Fifty Klebsiella spp. strains were isolated from rectal swabs of patients hospitalized in the neonatal intensive care unit (NICU). All strains were identified with API20E. The minimum inhibitory concentrations (MICs) of carbapenems were determined by the broth dilution method. The major five carbapenem genes (OXA-48, NDM, VIM, KPC, and IMP) were detected by the multiplex real-time PCR method. Results: It was found that 49 (98%) of the strains were resistant to ertapenem (MIC ≥ 2μg/mL) and imipenem(MIC ≥ 4 μg/mL), and 47 (94%) of the strains were resistant to doripenem (MIC ≥ 4 μg/mL)and meropenem(MIC ≥ 4 μg/mL).NDM was detected in 42%, OXA-48 in 16%, and VIM in one (2%) isolate, and NDM + OXA-48 co-existed in 36% of the isolates. The KPC and IMP genes were not detected. Conclusions: NDM and NDM co-existing with OXA-48 were prevalent in the NICU of Istanbul Medical Faculty Hospital. Paying attention to the hand hygiene of healthcare workers, screening of rectal swabs of hospitalized patients for the presence of carbapenem resistance strains, and isolation of infected patients can effectively control the spread of carbapenem-resistant strains.

The rate of extensively drug-resistant and pan-resistant gram-negative rods isolated as infectious agents is increasing around the world and in Turkiye. One of the important options in the treatment of these infections is the combined use of antibiotics. Therefore, the aim of this study was to investigate the in vitro effect of meropenem/colistin and meropenem/fosfomycin combinations on carbapenem-resistant gram-negative bacilli isolated as infectious agents. Escherichia coli (n= 6), Klebsiella pneumoniae (n= 10), Pseudomonas aeruginosa (n= 5), and Acinetobacter baumannii (n= 6) isolates were recovered from blood and tracheal aspirate samples of patients hospitalized in our hospital's intensive care unit were included in the study. In the first stage of the combination study, minimal inhibitory concentrations (MIC) were investigated by broth microdilution for meropenem and colistin, and agar dilution methods for fosfomycin. In the second stage of the study, synergy, partial synergy, indifference, and antagonistic effects were investigated with the checkerboard method for the meropenem/colistin combination and the agar dilution method for the meropenem/fosfomycin combination. The checkerboard results were interpreted as follows: fractional inhibitory concentration index (FICI) values <= 0.5 synergy, < 0.5-<= 1 partial synergy, > 1-<= 4 indifference and FIC values of > 4 antagonism. MIC values obtained in the study were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Of the 27 isolates studied with the broth microdilution method, 63% were found to be colistin-resistant and 37% susceptible. The MIC values of fosfomycin against Enterobacterales group bacteria were found to be in the range of 2-2048 mg/L. Two of the six E.coli isolates and nine of the 10 K.pneumoniae isolates were found to be resistant to fosfomycin (IV). The MIC values of >= 128 mg/L were found in all 11 non-fermentative gram-negative rods with intrinsic resistance to fosfomycin. In the combination of meropenem/colistin, synergy and partial synergy were observed in 11 (40.7%) of 27 isolates, an indifference effect was observed in 13 (48.2%), and antagonistic effects were observed in three (11.1%) of the isolates. The synergy and partial synergy effects of this combination were 37.5% for Enterobacterales group bacteria, 50% for E.coli, and 30% for K.pneumoniae. Regarding the 11 non-fermentative gram-negative rods included in the study, 83.3% synergy and partial synergy was found in A.baumannii for the meropenem/colistin combination, while no synergy and partial synergistic effect was found in P.aeruginosa. Meropenem/fosfomycin synergy and partial synergy effects were 83.3% (5/6) for E.coli, 100% (8/8) for K.pneumoniae, 100% (6/6) for A.baumannii, and 25% (1/4) for P.aeruginosa. In all of the isolates studied, meropenem/fosfomycin combination was found to be more effective than the meropenem/colistin combination. It would be meaningful to support these data obtained in vitro with clinical efficacy results to be obtained as a result of the application of antibiotics in vivo, taking into account the pharmacokinetic and pharmacodynamic properties of the antibiotics used in this study.

Aim: Antibiotic resistance is a major health problem. Recently, probiotics are used in the field of alternative/supportive medicine. Thus, in this study, we aimed to evaluate the in vitro inhibitory effects of four different cell-free supernatants (CFSs) of lactobacilli species (L. fermentum, L. plantarum, L. acidophilus and L. rhamnosus) on clinically isolated Methicilin-resistant Staphylococcus aureus (MRSA) strains, Vancomycin-resistant Enterococcus (VRE) strains, and Carbapenem-resistant Klebsiella (CRK) strains. Materials and Methods: Lactobacillus strains were grown in de Man Rogosa Sharpe broth; after filtration, CFSs were diluted to obtain 25, 50, and 100% concentrations. Pathogen bacteria were grown in tryptic soy broth with and without CFSs in a micro-plate. The bacterial growths were measured using spectrophotometric method after four hours of incubation at 37°C. One-way ANOVA followed by Dunnett’s multiple comparisons and Kruskal-Wallis test were used for statistical analyses. Results: All tested CFSs at all concentrations were found to inhibit growth of MRSA, VRE, CRK strains; the results were found statistically significant (p<0.0001). At 50% concentrations, all CFSs were found to be most effective on MRSA growth. The CFSs of L.fermentum, L.acidophilus and L.plantarum were found to be most inhibitory at 50% concentration on VRE growth. 50% diluted CFSs of L.fermentum and L.plantarum were found to be effective on growth of CRK. All results were found statistically significant (p<0.0001). Conclusion: In our study, our results support that CFSs of lactobacilli strains inhibit growth of multi-drug resistant bacteria. Their inhibitory effects were dependent on microorganisms and CFS concentrations.

Background: The human gut microbiota is an extensive population of microorganisms, and it shows significant variations between periods of optimal health and periods of illness. Vancomycin-resistant Enterococcus (VRE) and carbapenem-resistant Klebsiella pneumoniae (CRKP) are both pathogenic agents (BPAs) that can colonize in the gut after dysbiosis of microbiotal composition following antibiotic treatment. Methods: This study aimed to investigate the impact of antibiotics on the microbiotal composition of the gut. For this purpose, the first pass meconiums of 20 patients and the first rectal swabs containing BPAs of the same patients after antibiotic treatment were studied using next-generation sequencing-based 16S rRNA gene analysis. The V1–V9 region of 16S rRNA was sequenced with Oxford Nanopore. Results: Twenty-five phyla were detected in the meconiums, and 12 of them were absent after antibiotic treatment. The four most prevalent phyla in meconiums were Bacillota, Pseudomonadota, Bacteroidota, and Actinomycetota. Only the relative abundance of Pseudomonadota was increased, while a significant decrease was observed in the other three phyla (p < 0.05). A significant decrease was observed in alpha-diversity in rectal swabs containing BPAs versus meconiums (p = 0.00408), whereas an increased variance was observed in beta-diversity in all samples (p < 0.05). As a result of a LEfSe analysis, Pseudomonadota was found to have a higher relative abundance in rectal swabs, and Bacillota was significantly higher in the meconiums of the twins. Conclusions: Our study strongly verified the relationship between the administration of antibiotics, dysbiosis, and colonization of BPAs in the infants’ gut microbiota. Further research would be beneficial and needed, comprising the natural development process of the infants’ gut microbiota.