Acta microbiologica et immunologica Hungarica最新文献

The widespread use of antimicrobial agents correlated with the increasing incidence of nosocomial infections and bacterial antibiotic resistance. These have become major challenges in the prevention and control of hospital-acquired infections worldwide. The aims of this study were to analyze the distribution and characteristics of ESKAPE pathogenic bacteria and their antibiotic resistance profile among clinical isolates from a tertiary hospital in China from 2018 to 2023. The results showed that a total of 20,472 non-duplicated pathogenic bacteria were isolated from clinical specimens in this hospital between 2018 and 2023, of which the top five pathogenic bacteria were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii. In case of E. coli the main detected resistance genes were blaCTX-M, blaTEM and blaOXA. K. pneumoniae mainly carried blaOXA, blaKPC and blaNDM genes. P. aeruginosa was mainly positive for blaOXA, AmpC type beta-lactamases and blaVIM genes. A. baumannii mainly carried ArmA, blaTEM and cas3 genes. S. aureus was mainly positive for mecA, erm(C) and erm(A) genes. In this study, we have found that the antibiotic resistance of common pathogens from clinical isolates in a tertiary hospital in China in the past 6 years is severe, and A. baumannii was particularly a prominent pathogen. There is an urgent need to strengthen the prevention and control of nosocomial infections and antimicrobial drug management in order to curb the spread of multidrug-resistant bacteria.

Candida auris spreads rapidly and causes outbreaks worldwide. Strict infection control is critical to control its spread; however, it is challenging and requires a special approach. This study aims to investigate the colonization and infection of C. auris in intensive care units (ICUs), analyses its susceptibility, and mortality rates, and contributes to an effective infection control.An infection control study was planned, and a C. auris infection control bundle and checklist were developed. During the study's pre-intervention, intervention, and post-intervention periods, C. auris candidemia cases and colonized patients were identified. Until the infection control intervention, all the candidemia cases, antifungal resistance, and mortality were investigated retrospectively. Clinical isolates were identified by phenotypic and genotypic characterization using MALDI-TOF MS Biotyper (Bruker Daltonics, Bremen, Germany) and sequencing.During the pre-intervention, intervention, and post-intervention periods, 26 C. auris cases were identified. Pan-resistant C. auris isolates were 3.84%, and the multidrug resistance was 65.38%. With the infection control intervention, the number of colonized patients decreased (pre-intervention 9.61‰, intervention 6.19‰, post-intervention 5.20‰). Candidemia incidence decreased from 4.09 to 2.3‰. No new cases of candidemia were observed at the end of the study.The risk of new cases is elevated in the rooms where multiple C. auris cases have been previously isolated. Mortality rate was high; namely, 76.92% of patients died, and 19.23% of strains were resistant to anidulofungin, one of the most commonly used antifungals. Despite the short implementation period, the infection control bundle and checklist have been demonstrated to be effective in controlling C. auris spread in the ICU.

Multidrug resistant (MDR) gram-negative bacilli associated with hospital-acquired infections are commonly resistant to carbapenems. Klebsiella pneumoniae is a common MDR Enterobacterales in Thailand. In this study, we investigated the distribution of five carbapenemase genes (blaNDM, blaOXA-48, blaIMP, blaVIM, and blaKPC) among 62 carbapenem resistant K. pneumoniae (CRKP) collected in 2022 from patients admitted to a tertiary care hospital in Bangkok. The frequencies of isolates carrying a single carbapenamase gene were 39% for blaOXA-48 and 19% for blaNDM. Interestingly the frequency of the carriers of both genes was as high as 29% and none of the isolates carried blaKPC, commonly reported elsewhere. The studied genes were not identified in 7 isolates (11%). CRKP carrying blaNDM was more frequently identified in medical wards, associated with higher mortality rate and 100% resistant to ceftazidime/avibactam while the one carrying only blaOXA-48 was 92% susceptible to ceftazidime/avibactam. This study confirms the advantage of molecular methods for differentiating between mechanisms of carbapenem resistance in K. pneumoniae.

Helicobacter pylori is a major pathogen infecting over half of the global population, causing conditions like gastritis, ulcers, gastric cancer, and lymphoid tissue lymphoma. This study investigated the prevalence of H. pylori in 100 gastric biopsy samples from patients with dyspepsia and analyzed antibiotic resistance and virulence genes (cagA, vacA, iceA, and babA) using polymerase chain reaction (PCR). Diagnosis was performed via PCR, culture, rapid urease test, and histopathological examination, with antibiotic susceptibility assessed through the E-test method.The study was conducted between September 2022 and February 2023. The study found that 34% of samples were PCR-positive for H. pylori, while culture, histology examination, and rapid urease test showed positivity rates of 23%, 53%, and 63%, respectively. Alarmingly, antibiotic resistance was prevalent, with 100% resistance to clarithromycin and metronidazole, 39.1% to tetracycline, and 34.8% to levofloxacin. Virulence gene analysis revealed high positivity rates: cagA (53%), babA (29%), iceA1 (20.6%), iceA2 (41.2%), and vacA (97.1%), with the vacA s1m2 allele variant being most common (55.8%).These findings underscore the significant role of virulence factors like cagA and vacA in H. pylori pathogenesis and the severity of related diseases. The study highlights the urgent need for routine antimicrobial susceptibility testing to guide treatment amidst escalating antibiotic resistance. It also emphasizes the value of molecular diagnostics, such as PCR, for accurate and rapid detection of H. pylori and its virulence determinants. These insights are critical for improving the management of H. pylori-associated diseases and combating antibiotic resistance globally.

To identify antibiotic resistant genes and assess the clonality of carbapenem-resistant Enterobacter cloacae (CRECL) isolates from a hospital setting, altogether fifty-two clinical CRECL isolates were collected from 2012 to 2023. Antibiotic resistance genes including blaNDM, blaVIM, blaIMP, blaOXA-48, blaCTX-M-1 and blaTEM, were analyzed by PCR and nucleic acid sequencing. Sequence data were compared with those in the National Center for Biotechnology Information database. Clonality analysis was performed by ERIC-PCR. Among the 52 isolates, urine samples (23.1%) were the most common source, followed by puncture fluid (13.5%). The isolates were predominately obtained from urology (15.4%), followed by hepatobiliary surgery (11.5%). All isolates exhibited carbapenem resistance, with resistance rates of 88.5%, 84.6%, and 94.2% to imipenem, meropenem, and ertapenem, respectively. This was frequently accompanied by co-resistance to fluoroquinolones (67.2% to ciprofloxacin) and aminoglycosides (61.5% to tobramycin), likely due to the co-existence of multiple resistance genes on mobile genetic elements such as plasmids. However, all isolates remained sensitive to polymyxins, 67.2% to tigecycline and 50% to amikacin. Several carbapenem resistance genes were detected in isolates, with blaNDM-1 being the most abundant (40.4%), followed by blaNDM-5 (21.2%). Additionally, blaOXA-48 (3.8%), blaIMP-6 (1.9%) and blaVIM-1 gene (1.9%) have also been found in a few isolates. Among β-lactam resistance genes, blaTEM-1 (42.3%) is the most prevalent, followed by blaCTX-M-1 gene (23.1%). Clonality analysis classified the isolates into five clusters (A-E). Multiple strains exhibited >86% similarity, indicating clonal spread. In conclusion, CRECL isolates demonstrated extensive antimicrobial resistance, primarily mediated by blaNDM-1 and blaTEM. Clonality analysis revealed the presence of clonally related strains across different hospital departments, suggesting potential nosocomial transmission. Enhanced surveillance, strict disinfection and isolation measures are necessary to prevent the spread of CRECL and mitigate nosocomial infections and dissemination of epidemics.

In the food industry, one of the main challenges is providing products free from pathogens that cause high morbidity and mortality in consumers. This situation has been further aggravated by the emergence of antibiotic-resistant strains, with some notable examples such as extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC), due to their impact on the healthcare sector, causing difficult-to-treat infections. Therefore, the objective of this study was to evaluate the prevalence of ESBL-EC and their antibiotic resistance patterns in chicken meat sold in Tamaulipas, Mexico. A total of 130 chicken meat samples from 17 municipalities in Tamaulipas were analyzed during 2024. An average prevalence of 20.7% of ESBL-EC was detected. Thirty-eight different antibiotic resistance patterns were identified, and 85.1% were multidrug-resistant (MDR). When classifying the strains into phylogroups, 63.8% were considered commensal (groups A and B1) and 36.1% pathogenic (groups B2 and D). The results of this study demonstrate the presence of pathogenic MDR ESBL-EC strains in chicken meat sold in Tamaulipas, suggesting possible improper handling of this meat, which may pose a risk to consumers. These results also emphasize the need to monitor the presence of antibiotic resistant strains in chicken meat and other foods sold in Mexico.

Stenotrophomonas maltophilia is an opportunistic pathogen that can cause infections especially in hospital settings and in immunocompromised individuals. Due to its resistance to many broad-spectrum antibiotics, treatment options that can be used in clinical practice are limited. This study aims to evaluate the susceptibility profiles of S. maltophilia isolates to antimicrobial agents commonly used in treatment and to investigate the presence of different classes of integrons and sul genes responsible for resistance. The study included 100 S. maltophilia isolates from various clinical samples sent to Balıkesir University Health Practice and Research Hospital Medical Microbiology Laboratory between 2017 and 2023. The BD Phoenix™ M50 Automated System was used for bacterial identification and antibiotic sensitivity testing. The susceptibility of isolates to trimethoprim-sulfamethoxazole was also studied by disk diffusion method. All isolates were investigated for sul1, sul2 genes and integron-associated integrase genes by polymerase chain reaction. The susceptibility rates of isolates to trimethoprim-sulfamethoxazole, levofloxacin and ceftazidime were determined as 96%, 66% and 38%, respectively. Polymerase chain reaction results showed, intI1 and sul1 genes were found to be positive together in two isolates resistant to trimethoprim-sulfamethoxazole, while sul1 and sul2 genes were found in two separate isolates sensitive to trimethoprim-sulfamethoxazole. The intI2 gene was not detected in any isolate. This study addresses the clinically important problems of S. maltophilia infections, which are increasingly difficult to treat due to intrinsic and acquired resistance mechanisms. By providing valuable information on antimicrobial susceptibility and resistance profiles of S. maltophilia isolates, it contributes to national data and guides efforts to control resistance and promote rational antibiotic use.

Stenotrophomonas maltophilia has emerged as an opportunistic pathogen originating from the environments, causing nosocomial infections, particularly in immunocompromised individuals and patients with cystic fibrosis. Although this microorganism exhibits low virulence, its infections are associated with high morbidity and mortality rates. S. maltophilia is intrinsically resistant to many antimicrobial agents used in clinical practices, therefore, posing significant treatment challenges. The multidrug resistance in S. maltophilia results from a combination of intrinsic, adaptive, and acquired mechanisms. S. maltophilia genome carries an array of genes encoding multidrug efflux pumps, which are key contributors to its broad-spectrum antibiotic resistance by expelling a wide range of drugs and reducing their intracellular concentrations to nontoxic levels. The majority of these efflux pumps belong to the resistance-nodulation-cell division (RND) family, while a lesser fraction is classified under the major facilitator superfamily (MFS) and the adenosine triphosphate binding cassette (ABC) family. In terms of function, substrate specificity, and complex gene regulation, these multidrug efflux pumps contribute not only to the survival of S. maltophilia under antibiotic stress but also to its resilience against other chemical challenges, including oxidative stress-generating substances and biocides. The roles of certain efflux pump systems in acquired and adaptive antibiotic resistance, as well as their potential applications as drug targets to enhance the efficacy of routinely used antibiotics through the use of small molecules capable of functioning as efflux pump inhibitors, are also discussed. A deeper understanding of these mechanisms can contribute to the more effective management against antibiotic-resistant S. maltophilia.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is one of the major Gram-negative bacteria in human infections, which can cause pneumonia, sepsis, meningitis, and abscess. However, the current therapy for CRKP infection is polymyxin and tigecycline. The aim of this study is to analyze the in vitro antibacterial effects of cefoperazone/sulbactam (SCF) combined with ceftazidime (CAZ), imipenem/cilastatin (IMI), and meropenem (MEM) against CRKP harbouring different antibiotic resistance genes. In this study, fifteen clinical isolates of CRKP from January to December 2023 were taken from our hospital for bacterial identification and confirmation of carbapenemase genotypes, and the minimum inhibitory concentration (MIC) of SCF, CAZ, IMI, and MEM were determined by broth microdilution method. The results of combined drug sensitivity test were determined by checkerboard method and characterized with fractional inhibitory concentration (FIC). The combined antibacterial activity was determined by time-kill curve. The results showed that among the 15 CRKP strains, 9 carried blaKPC gene, 3 carried blaNDM gene and 3 carried blaOXA-48-like gene. The MIC values determined by broth microdilution method showed better sensitivity of KPC-producing CRKP to four antimicrobial drugs including SCF. However, blaNDM as well as blaOXA-48-like genotypes showed strong resistance to all four antimicrobial drugs. The FIC values of SCF combined with CAZ, IMI and MEM showed that all tested antibacterial agents had the best effect on KPC-producing CRKP, and had no obvious additive effect on other CRKP. The results of time-kill curve showed that SCF combined with IMI had good antibacterial effect. This study found that SCF combined with IMI has a synergistic antibacterial effect on KPC producing carbapenem-resistant K. pneumoniae, which could provide reference for clinical practice.

Invasive aspergillosis primarily affects individuals with compromised immune systems. This study endeavors to suggest the importance of early diagnosis and treatment related to central nervous system (CNS) aspergillosis. Recognizing the typical and atypical imaging characteristics of CNS aspergillosis enables the early and aggressive treatment of an otherwise rapidly fatal infection. We reported a case of an elderly patient with a history of non-Hodgkin lymphoma and prostate cancer who underwent repeated chemotherapy and subsequently experienced a sudden disturbance of consciousness. The diagnosis was affirmed through metagenomic next-generation sequencing (mNGS) of sputum and cerebrospinal fluid. The treatment encompassed systemic antifungal agents and intrathecal injection of amphotericin B. Metagenomic sequencing of sputum and cerebrospinal fluid detected Aspergillus fumigatus and Aspergillus flavus, leading to a diagnosis of invasive pulmonary and CNS aspergillosis. Although the patient actively received combined systemic antifungal drugs (voriconazole and amphoteric B liposome) and intrathecal injection of amphotericin B, he ultimately succumbed to the infection. A review of similar cases from PubMed and Medline from 2014 to 2024, encompassing 64 patients, showed that while early diagnosis and combination therapy have improved survival rates, outcomes remain suboptimal. Invasive aspergillosis has a high mortality rate and requires early diagnosis and treatment. Metagenomic sequencing of pathogenic microorganisms constitutes a convenient approach to facilitate the early diagnosis of aspergillosis. Voriconazole is the preferred treatment for invasive aspergillosis. When CNS aspergillosis emerges, it might be necessary to combine other systemic antifungal agents with intrathecal injection of amphotericin B.