Acta microbiologica et immunologica Hungarica最新文献

The aim of the study was to detect carbapenemase genes in clinically significant carbapenemase-producing Enterobacterales (CPE) and assess their susceptibility to newer antibiotics: ceftazidime-avibactam, ceftolozane-tazobactam, imipenem/relebactam, meropenem-vaborbactam, and cefiderocol. From January 2018 to February 2019, 866 Gram-negative bacilli were isolated, and among them 775 were identified as Enterobacterales. Out of the tested Enterobacterales, phenotypic testing revealed potential carbapenemase production in 95 isolates. A total of 56 clinically significant isolates were selected for molecular analysis. Species identification and antimicrobial susceptibility for conventional antibiotics was done using the VITEK 2 system, while carbapenemase genes were detected via Multiplex PCR. Antimicrobial susceptibility for newer antibiotics was determined by the MIC test strips. The predominant genotypes were blaNDM (39.3%) and blaOXA-48 (37.5%), with Klebsiella pneumoniae as the most prevalent producer (71.42%). Cefiderocol showed 100% effectiveness against all isolates. Ceftazidime-avibactam demonstrated high activity against OXA-48 and KPC producers (95.5% and 100% susceptibility, respectively). Meropenem-vaborbactam significantly improved susceptibility among NDM-. OXA-48/NDM-, and OXA-48-producing isolates, and imipenem-relebactam among OXA-48 CPE. Statistically significant differences in susceptibility were observed for OXA-48 and NDM producers to imipenem (P < 0.01), imipenem-relebactam (P < 0.001), and ceftazidime-avibactam (P < 0.001). In conclusion, the high prevalence of NDM-producing CPE strains significantly reduces the effectiveness of newer antibiotics. Cefiderocol appears to be the most effective therapeutic option, particularly for NDM producers, where it often represents the only viable treatment choice, while ceftazidime-avibactam is an effective option for OXA-48 producers. Statistically significant differences in susceptibility highlight the need for early detection of carbapenemases in clinical practice.

This study aimed the identification of anaerobic bacteria isolated from blood cultures and the determination of antibacterial susceptibility of the isolates. The study material comprised of 5,282 blood samples taken between 2018 and 2020. The samples were incubated in a BacT/ALERT system. The species identification of the isolates was performed by three methods namely, BBL Crystal Anaerobe system, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16S rRNA gene sequence analysis. Antibacterial susceptibility testing was performed using the disk diffusion method with benzylpenicillin, clindamycin, piperacillin-tazobactam, meropenem, and metronidazole disks. In the BacT/ALERT system, 45 anaerobic bacterial isolates were recovered from 39 (0.74%) of the samples that showed growth signs in blood culture bottles. The BBL Crystal Anaerobe system and 16S rRNA gene sequence analyses enabled the genus and species identification of all 45 isolates (100%), whereas with MALDI-TOF MS, only 37 (82.2%) of the isolates were able to be identified. Antibacterial resistance rates of the isolates to piperacillin/tazobactam, clindamycin, benzylpenicillin, meropenem, and metronidazole were detected as 100%, 73.8%, 40%, 9.8%, and 5.5%, respectively. MALDI-TOF MS showed a higher level of compatibility with 16S rRNA gene sequence analyses, compared to the BBL Crystal Anaerobe system. The high rates of susceptibility to meropenem and metronidazole suggested that these antibiotics are options for the empirical treatment of anaerobic bacterial infections.

The study was conducted in the microbiology laboratory of the First Affiliated Hospital of Hainan Medical University, Haikou, China, from January 2019 to December 2023. A total of 316 consecutive non-duplicate isolates were collected and identified, that belonged to the Bacteroides fragilis group. Identification of the isolated strains was performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The minimum inhibitory concentration (MIC) of seven antibiotics was determined by agar dilution method. The presence of cfiA, ermF, and nim genes was determined by polymerase chain reaction (PCR). Correlations between the presence of resistance genes and the MIC values of antibiotics were determined using the Pearson correlation coefficient. In the identification process, 214 isolates (67.7%) were identified as B. fragilis, 52 (16.4%) as Bacteroides thetaiotaomicron, 17 (5.4%) as Bacteroides ovatus, 12 (3.8%) as Bacteroides uniformis, 10 (3.2%) as Phocaeicola vulgatus (=Bacteroides vulgatus), 7 (2.2%) as Bacteroides stercoris, and 4 (1.3%) as Parabacteroides distasonis. The presence of cfiA gene moderately correlated with the MIC of imipenem and meropenem (r = 0.34 and r = 0.42, respectively), while resistance to clindamycin and the presence of ermF gene exhibited a very strong correlation (r = 0.72). In the current study, the most active antimicrobial agents against B. fragilis group bacteria were found to be meropenem, imipenem, metronidazole, and piperacillin/tazobactam; however, resistance to clindamycin renders its empirical use inappropriate.

The spread of NDM-1-harboring Klebsiella pneumoniae is a worldwide concern. In this study the whole-genome sequence (WGS) of a carbapenem- and colistin-resistant K. pneumoniae 838Gr strain is presented. This strain was isolated from a urine sample of a patient in the Intensive Care Unit (ICU) at Volos Hospital, Greece. The initial assembly produced 224 contigs with a combined genome size of 5,561,803 bp and a GC content of 57.21%. The K. pneumoniae strain carried IncR, IncFIA, IncC, and repB (R1701) replicons. Multilocus sequence typing (MLST) analysis revealed that the isolate belonged to the sequence type 11 (ST11) and serogroup KL24 and O2a. The WGS analysis identified several beta-lactamase genes (blaTEM-1B, blaCTX-M-15, blaNDM-1, blaOXA-1, blaVEB-1, blaOXA-10, and blaSHV-11) alongside resistance genes for other antibiotic classes, including floR2, cmlA1, cmlA5, catB3, arr-3, aph(6)-Id, aadA2. Colistin resistance was attributed to specific point mutations in pmrB (R256G, T140P). This is the first report of a carbapenem- and colistin-resistant K. pneumoniae ST11 strain in Greece. The findings of this study highlight the urgent need for increased surveillance and stringent infection control.

Treatment options are limited for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates due to the production of metallo-β-lactamase (MBL). The ceftazidime-avibactam (CZA)/ aztreonam (ATM) combination represents a new therapeutic approach in MBL-positive isolates. Our study aims to determine distribution of carbapenemase genes in CRKP isolates and to investigate the in vitro synergistic effect of the CZA/ATM combination.Our study included 48 CRKP strains isolated from various clinical samples. Identification was performed using MALDI-TOF MS (bioMérieux, France), and susceptibility was tested with Vitek-2 (bioMérieux). The susceptibility to CZA and ATM was determined using CZA 30/20 µg and ATM 30 µg (Oxoid™,UK) disks. Carbapenemase genes VIM, NDM, IMP, KPC, OXA-23, OXA-58, OXA-48, and OXA-51 were investigated in only 44 isolates using the Bio-Speedy Carbapenem resistance qPCR (Bioexen, Turkiye) kit. Synergy testing was evaluated with double disk diffusion, gradient strip (bioMérieux)/disk diffusion, and broth disk elution methods.Out of 48 carbapenem-resistant isolates, 40 (83.3%) isolates showed resistance to CZA and 46 (95.8%) to aztreonam. Synergy was detected with all three methods in all isolates identified as resistant to CZA, CZA-sensitive isolates were not included in this evaluation. The most frequently detected carbapenemase genes were NDM+OXA-48, found in 28 (63.6%) of the isolates.Although the NDM+OXA-48 coexistence predominates in our center, in vitro synergy between CZA and ATM was detected in all of CZA-resistant isolates. Performing the CZA+ATM synergy test and reporting the result is crucial for choosing appropriate treatment in CRKP infection.

Aerococcus urinae is an uncommon uropathogen that mainly affect the elderly with predisposing conditions. Aim of the present study was to investigate the clinical and microbiological characteristics of patients with urinary tract infections (UTIs) by A. urinae and determine the antimicrobial susceptibility patterns of the isolates, over the last 3 years at our institution. The medical records and microbiological data of patients from whom A. urinae was isolated from urine cultures at the university hospital of Heraklion, Crete, Greece, between 2020 and 2022, were retrospectively analyzed. The isolates were identified by the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Susceptibilities for antimicrobial agents were determined by the disk diffusion method and results were interpreted using the 2024 EUCAST breakpoints. The minimum inhibitory concentration for fosfomycin was evaluated by the MIC Test Strip method. A. urinae was encountered in cultures of 24 patients. The median patient's age was 72 years, and females slightly outnumbered males. Underlying diseases such as urologic disease, chronic lung disease, chronic kidney disease, heart disease, diabetes mellitus and dementia were found in 79.2% of patients. Two of the patients did not meet the criteria for a UTI. Susceptibility rates to penicillin, amoxicillin, meropenem, ciprofloxacin, levofloxacin, rifampicin, vancomycin, nitrofurantoin and fosfomycin were 100%, 100%, 100%, 83.3%, 79.2%, 100%, 100%, 95.8%, and 91.7%, respectively. Further surveillance studies and clinical trials are needed to confirm our data and to investigate the in vivo efficacy of the antimicrobial agents to treat UTIs by A. urinae.

The incidence of lower respiratory tract infections (LRTIs) caused by multidrug-resistant organisms (MDRO) has been high in recent years. However, traditional etiological detection methods have not been able to meet the needs for clinical diagnosis and prognosis of LRTIs. The rapid development of metagenomic next-generation sequencing (mNGS) provides new insights for diagnosis and treatment of LRTIs. We conducted a retrospective study on 95 patients with lower respiratory tract infections caused by MDRO admitted to our respiratory department from January 2022 to December 2023. These patients underwent mNGS testing and conventional culture testing. Additionally, 150 patients without lower respiratory tract infections caused by MDRO during the same period were included as the non-MDRO group. General information was collected, and Logistic regression analysis was performed to identify risk factors for MDRO infections in patients with lower respiratory tract infections. Our results show that the time to pathogen detection by mNGS was 50.76 ± 1.730 h, that is significantly shorter than 55.53 ± 2.782 h required for conventional culture testing. The pathogen detection rate by mNGS was 89.47% (85/95), higher than the 67.37% (64/95) identified by conventional testing. In terms of pathogen genus distribution, mNGS detected a total of 279 pathogens, while conventional testing detected 121 pathogens. Logistic multivariate regression analysis identified that the use of more than two antibiotics, invasive procedures, invasive mechanical ventilation for ≥7 days, and stay in the respiratory intensive care unit (RICU) for ≥7 days were the main influencing factors for lower respiratory tract infections caused by MDRO (P < 0.05).

Klebsiella pneumoniae is a major pathogen associated with hospital-acquired infections, particularly those involving multidrug-resistant strains. Carbapenem resistance, often driven by carbapenemases such as KPC, VIM, OXA-48, and NDM, poses a significant challenge in clinical settings. This study reports on K. pneumoniae strain A165, isolated from a blood culture of a 51-year-old female patient hospitalized for respiratory distress post-SARS-CoV-2 infection. This K. pneumoniae strain exhibited resistance to several antibiotics, including carbapenems, cephalosporins, aminoglycosides, and fluoroquinolones, but remained susceptible to gentamicin, colistin, and trimethoprim-sulfamethoxazole. Next-generation sequencing was performed on Ion torrent platform, that revealed a genome size of 5,676,404 bp, including a chromosome and six plasmids. The strain was classified as sequence type 11 (ST11), a high-risk lineage associated with carbapenem resistance. The resistome of A165 included multiple β-lactamase genes, such as blaNDM-1 and blaOXA-48, as well as genes conferring resistance to other antibiotic classes. The virulome analysis identified genes involved in iron acquisition (yersiniabactin operon genes: ybtE, ybtT, irp1, irp2; aerobactin receptor: iutA), adhesion (mrkA-J, fimA-K), capsule and biofilm formation (rcsA, rcsB, ompA) and resistance to complement (traT) contributing to its pathogenic potential. The mobilome analysis revealed nine insertion sequences, including ISKpn1, ISKpn18, ISKpn43, ISKpn28, ISKpn14, ISEcp1, and IS6100. The strain also harbored six replicons: Col440II, ColRNAI, IncFIA(HI1), IncFIB(K), IncFII(K), and IncR, which are associated with the horizontal transfer of resistance and virulence genes. Comparative analysis with global isolates demonstrated the widespread dissemination of carbapenemase-producing K. pneumoniae, with notable occurrences in Europe, Asia, and the Americas. This study highlights the growing concern of multidrug-resistant K. pneumoniae in hospital settings and emphasizes the need for robust surveillance and infection control measures.

Shigellosis, a diarrheal disease caused by Shigella species, is a significant public health concern, particularly in developing countries with inadequate sanitation systems. This study aimed to investigate the patterns of antibiotic resistance, ESBL and AmpC genes, integrons, and enterotoxin genes in Shigella species isolated from patients with gastroenteritis in Northeast Iran. This cross-sectional study was conducted between January 2017 and December 2019 at a tertiary care hospital in Northeast Iran. A total of 110 Shigella isolates were collected from stool samples of patients with gastroenteritis. The isolates were identified using conventional biochemical tests and confirmed by PCR. The highest resistance rates were detected for ampicillin (88.2%) and cotrimoxazole (84.5%). Altogether 64.5% of isolates exhibited multidrug resistance however, ESBL and AmpC phenotypes were detected in 34.54% and 1.81% of isolates, respectively. Interestingly, blaCTX-M-15 and blaTEM were detected in all ESBL-positive isolates but integron class 1, 2, and 3 were identified in 97.3%, 76.4%, and 59.1% of isolates, respectively. The sen gene was present in 72.7% of the isolates. In this study CTX-M-15 production was detected in 31 strains of Shigella sonnei and in 7 strains of Shigella flexneri. The high prevalence of multidrug-resistant Shigella isolates is concerning and shows the need for continuous monitoring and rational use of antibiotics.

This study investigated a strain of Klebsiella pneumoniae, identified as GRTHES, which exhibited extensive antibiotic resistance. The strain was resistant to all beta-lactams, including combinations with newer agents such as meropenem/vaborbactam and imipenem/relebactam, as well as to aminoglycosides, fluoroquinolones, fosfomycin, trimethoprim-sulfamethoxazole and colistin. It remained susceptible to tigecycline. Whole-genome sequencing was performed by Ion Torrent platform on the K. pneumoniae strain. Genomic analysis revealed a genome length of 5,808,650 bp and a GC content of 56.9%. Advanced sequencing techniques and bioinformatic tools were used to assess resistance genes and plasmid replicons, highlighting the emergence of multidrug resistance and virulence traits. The strain carried blaNDM-1 and blaKPC-3 genes and was designated to KL107 O2afg type. Colistin resistance-associated mgrB/pmrB gene mutations were present, and the strain also harbored yersiniabactin-encoding ybt gene. Our findings provide insights into the genomic context of blaNDM-1 and blaKPC-3 carbapenemase-producing K. pneumoniae and emphasize the importance of continuous surveillance and novel therapeutic strategies to combat multidrug-resistant bacterial infections. It is the first time that an NDM-1 and KPC-3 co-producing strain of K. pneumoniae ST512 is identified in Greece. This study highlights the essential role of genomic surveillance as a proactive strategy to control the spread of carbapenemase-producing K. pneumoniae isolates, particularly when key antimicrobial resistance genes, such as blaNDM-1 and blaKPC-3, are plasmid-mediated. Detailed characterization of these isolates could reveal plasmid similarities that facilitate adaptation and transmission within and between hospitals. Although data on patient movements are limited, it is plausible that carbapenem-resistant isolate was selected to co-produce KPC and NDM through plasmid acquisition.