Acta Microbiologica Et Immunologica Hungarica[JOURNAL]
Sun
200 papers
Molecular detection of virulence genes and antimicrobial resistance in Salmonella isolates from avian and human sources in northeastern Algeria.
Kout A, Boufermes R, Elgroud R … +3 more , Binay B, Khelifi D, Berredjem H
Acta Microbiol Immunol Hung · 2025 Oct · PMID 40632593 · Publisher ↗
Products of avian origin are one of the major Salmonella reservoirs, responsible for serious public health concerns. Transmission and pathogenicity are mainly caused by molecular mechanisms, including chromosomal and pla...
Products of avian origin are one of the major Salmonella reservoirs, responsible for serious public health concerns. Transmission and pathogenicity are mainly caused by molecular mechanisms, including chromosomal and plasmid-encoded virulence factors. This study aimed to perform phenotypic identification, antibiotic resistance profiling against 15 antibiotics, and characterization of virulence factors of 80 Salmonella strains (30 from human and 50 from poultry), collected in Annaba and Constantine regions in Algeria.Antibiogram analysis and simplex PCR revealed complete resistance to four antibiotics: Ampicillin, Penicillin, Cephalotin and Cephoxetin. In addition, four virulence genes (spvA, spiC, spvC and pefA) were detected. These genes were identified in isolates from both avian and human origins, with variations in their distrubition frequencies. This study highlights the significant role of avian-derived Salmonella as a reservoir of antibiotic resistance and virulence genes, posing a serious threat to public health.Antibiotic resistance profiling revealed that avian isolates exhibited complete resistance (100%) to ampicillin, penicillin and cephalothin, followed by a high resistance rate of 98% to cefalexin and ceftriaxone. Moderate resistance levels, ranging from 76% to 46%, were observed against streptomycin, tetracycline, trimethoprim-sulfamethoxazole, ciprofloxacin, kanamycin and nalidixic acid. In contrast, low resistance rates were reported for gentamicin, amikacin, and chloramphenicol, at 20%, 18%, and 16%, respectively.On the other hand, human isolates showed complete resistance (100%) to ampicillin, penicillin, cephalothin and cefalexin. Moderate resistance (76%-46%) was observed against ceftriaxone, kanamycin, cefotaxime, gentamicin, trimethoprim-sulfamethoxazole, nalidixic acid, streptomycin, and chloramphenicol. Low resistance levels were detected for tetracycline, ciprofloxacin, and amikacin, at 26%, 20%, and 6.6%, respectively.These findings along with the widespread presence of virulence genes (spvA, spiC, spvC, and pefA) in both human and poultry isolates, underscore the potential for cross-species transmission and the urgent need for enhanced surveillance. The regional findings from Annaba and Constantine emphasize the importance of stricter antibiotic use policies in poultry farming.
High prevalence of carbapenem-resistant Escherichia coli ST410 from clinical isolates in Weifang, China.
Gao Y, Sun X, Wang H
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40531574 · Publisher ↗
The objective of our work is to identify antimicrobial-resistance genes and to analyze clonality of carbapenem-resistant Escherichia coli. A total of 75 carbapenem-resistant E. coli (CREco) strains were isolated in a Chi...
The objective of our work is to identify antimicrobial-resistance genes and to analyze clonality of carbapenem-resistant Escherichia coli. A total of 75 carbapenem-resistant E. coli (CREco) strains were isolated in a Chinese hospital from January 2021 to May 2023. The antibiotic susceptibility testing was conducted by BD PhoenixTM M50 System and Kirby-Bauer disk diffusion method. Whole-genome sequencing was performed on Illumina NovaSeq 6000 platform. Antimicrobial resistance genes were identified based on NCBI with ABRicate 0.8. Multilocus sequence typing (MLST) analysis for CREco was performed. Among the 75 CREco strains in this study, the most of them were isolated from urine samples (n = 20, 26.67%) at the intensive care unit (n = 14, 18.67%). Among the detected carbapenem resistance genes, blaNDM-5 was the most prevalent (n = 57, 76.00%), followed by blaNDM-4 (n = 3, 4.00%), blaNDM-9 (n = 3, 4.00%), and blaNDM-1 (n = 2, 2.67%). In addition, the colistin resistance gene mcr-1.1 (n = 11, 14.67%) and the tigecycline resistance gene tetX4 (n = 2, 2.67%) were also detected. The results of MLST revealed 25 sequence types (STs), and ST410 (n = 17) was the dominant clone. Other major STs included ST167 (n = 12), ST156 (n = 10), ST361 (n = 5), and ST101 (n = 4). Overall, CREco strains exhibited a high-level resistance rate to commonly used antimicrobial agents, and the most of them carried various NDM-coding genes, with blaNDM-5 being the predominant type. In this study, we demonstrated the diversity of carbapenem-resistant E. coli; however, the major clone was ST410. These results also show the dissemination of different clones of carbapenem-resistant E. coli.
Analysis of ESKAPE pathogens in clinical isolates in a tertiary care hospital in China from 2018 to 2023.
Zou L, Leng J, Gao W … +2 more , Zhou W, Zhang X
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40522743 · Publisher ↗
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 hospit...
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 infections in an intensive care unit: Antifungal resistance, mortality rates and infection control interventions.
Solak Grassie S, Karabıçak N, Ünalan Altıntop T
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40512568 · Publisher ↗
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 col...
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.
Diversity of carbapenemase genes among carbapenem resistant Klebsiella pneumoniae in a tertiary care hospital in Bangkok, Thailand.
Homkaew A, Wongsuk T, Boonsilp S … +3 more , Ckumdee J, Dubbs P, Palittapongarnpim P
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40493394 · Publisher ↗
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 in...
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.
Prevalence, antibiotic resistance and molecular characterization of virulence factors of Helicobacter pylori strains isolated from patients with dyspepsia.
Aydın E, Uzun AN, Perçin Renders D … +2 more , Çalışkan Kartal A, Coşgun S
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40408150 · Publisher ↗
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....
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.
Distribution of phylogroups and antibiotic resistance patterns of ESBL-producing Escherichia coli strains isolated from chicken meat in Tamaulipas, Mexico.
Rodríguez Chávez KA, Mandujano-Hernández JA, Rivera G … +2 more , Bocanegra-García V, Martínez-Vázquez AV
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40402650 · Publisher ↗
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-r...
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.
Detection of different carbapenemases and clonality analysis of carbapenem-resistant Enterobacter cloacae.
Wang Y, Sun X, Wang H
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40402649 · Publisher ↗
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 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.
Efflux pump systems as key contributors to multidrug resistance in Stenotrophomonas maltophilia: Physiological roles and gene regulation.
Vattanaviboon P, Dulyayangkul P, Mongkolsuk S … +1 more , Charoenlap N
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40402604 · Publisher ↗
Stenotrophomonas maltophilia has emerged as an opportunistic pathogen originating from the environments, causing nosocomial infections, particularly in immunocompromised individuals and patients with cystic fibrosis. Alt...
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.
Retrospective analysis of antibiotic resistance profiles and frequency of resistance genes in clinical Stenotrophomonas maltophilia isolates.
Erdiren N, Kula Atik T
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40402576 · Publisher ↗
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, treatmen...
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.
Antibacterial efficacy of cefoperazone/sulbactam in combination with various antimicrobials against carbapenem-resistant Klebsiella pneumoniae.
Xu C
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40266683 · Publisher ↗
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 infectio...
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 pulmonary and central nervous system aspergillosis: A case report and literature review.
Lu W, Ji R, Li W
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40131352 · Publisher ↗
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....
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.
NDM-1 and VIM-1 dual metallo-beta-lactamase producing Klebsiella pneumoniae ST15 high-risk clone from a blood culture of a patient at Intensive Care Unit in a Greek Tertiary Care Hospital.
Tsolakidou P, Kyriazidi MA, Varlamis S … +7 more , Chatzopoulou F, Frydas I, Kyriazidis KA, Kalinderi K, Mitka S, Skepastianos P, Chatzidimitriou M
Acta Microbiol Immunol Hung · 2025 Jun · PMID 40126596 · Publisher ↗
The emergence of carbapenemase-producing Klebsiella pneumoniae poses a significant global health threat, particularly in hospital settings. This study reports on the first detection of a pandrug-resistant (PDR) high-risk...
The emergence of carbapenemase-producing Klebsiella pneumoniae poses a significant global health threat, particularly in hospital settings. This study reports on the first detection of a pandrug-resistant (PDR) high-risk ST15 K. pneumoniae strain co-producing NDM-1 and VIM-1 in Greece. The isolate was recovered from a blood culture of a male patient admitted to the Intensive Care Unit (ICU) of Volos Hospital in July 2024. Next generation Sequencing (NGS) confirmed the presence of blaNDM-1 and blaVIM-1 genes. Other beta-lactamase type (CTX-M-15) was detected in association with NDM and VIM enzymes. Furthermore, this isolate was resistant to other antimicrobial agents, including aminoglycosides [aac(3)-II, aac(3)-IIe, aac(6')-Ib, aadA1, aph(3″)-Ib, aph(6)-Id, aph(3')-Ia), chloramphenicol (catB3), fluoroquinolones (qnrS1) and sulfonamides (sul1 and sul2). The Multilocus Sequence Typing revealed that the strain belonged to ST15. According to Kaptive the strain belonged to KL48. Our study provides new data about MBL producing K. pneumoniae in Greece. Thus, we report for the first time the co-expression of blaNDM-1 and blaVIM-1 in our country in ST15 K. pneumoniae. This study provides crucial epidemiological data on MBL-producing K. pneumoniae in Greece and highlights the urgent need for enhanced surveillance, infection control strategies, and access to last-resort antibiotics such as aztreonam-avibactam.
Genotypic analysis and biofilm formation of Acinetobacter baumannii clinical isolates.
Duymaz FZ, Budak F, Okumuş E
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40126588 · Publisher ↗
Acinetobacter baumannii is a significant nosocomial pathogen recognized for its multidrug-resistance (MDR) and capacity to endure in hospital settings. This study aims to investigate the clonal relationships of A. bauman...
Acinetobacter baumannii is a significant nosocomial pathogen recognized for its multidrug-resistance (MDR) and capacity to endure in hospital settings. This study aims to investigate the clonal relationships of A. baumannii isolates from diverse clinical samples, identify the sequence types of MDR isolates, and examine biofilm formation activity and biofilm-associated genes that contribute to persistence in hospital settings. A total of 90 A. baumannii isolates were analyzed. Bacterial identification and antibiotic susceptibility testing were conducted with MALDI-TOF MS and Vitek-2. REP-PCR was utilized to evaluate clonal connections, MLST was employed for specific isolates. Biofilm formation activity was assessed using the XTT reduction assay, and biofilm-associated genes were identified by PCR. REP-PCR revealed 29 genotypes, with Genotype A being identified as the endemic clone in 59% of isolates. Two isolates representing this genotype were found to belong to the ST2 clone. The majority of A. baumannii isolates possess biofilm-related genes and exhibit strong biofilm activity. In MDR isolates, ompA and csuE positivity were significantly higher than those non-MDR isolates (P = 0.003, P = 0.001). The csuE positive isolates were found to have significantly stronger biofilm activity than negative ones (P = 0.009). This study emphasizes the prevalence of a hospital-endemic, MDR A. baumannii genotype A, ST2 clone, and the genetic variability across isolates. No direct correlation was noted between MDR status and biofilm formation; however, some biofilm-related genes, notably csuE, were linked to stronger biofilm activity. These findings underscore the necessity for ongoing molecular surveillance and infection control measures to avert the dissemination of MDR A. baumannii in healthcare environments.
Antimicrobial resistance and virulence factors of Listeria monocytogenes isolated from fresh cheese products in Tamaulipas, Mexico.
Guel-García GP, Licea-Herrera JI, Vásquez-Villanueva J … +3 more , Rivera G, Bocanegra-García V, Martínez-Vázquez AV
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40126563 · Publisher ↗
Listeria monocytogenes is a foodborne opportunistic pathogen, that causes outbreaks and fatal cases worldwide. However, only few studies have been published in Mexico reporting the prevalence of this pathogen in food. Th...
Listeria monocytogenes is a foodborne opportunistic pathogen, that causes outbreaks and fatal cases worldwide. However, only few studies have been published in Mexico reporting the prevalence of this pathogen in food. Therefore, the objective of this current study is to evaluate the prevalence of L. monocytogenes in cheese sold in Tamaulipas, Mexico, and its potential risk to the population. For this purpose, samples were taken in 100 stores during the months of February, June and October 2023, and a total of 300 cheese products in 10 municipalities of Tamaulipas, Mexico were collected. Identification was performed by culture and PCR. Ten virulence factors were also analyzed and susceptibility testing to 14 antibiotics was performed. As a result, a prevalence of L. monocytogenes was detected in 12%. The most frequently detected virulence factors were actA (83.3%, 30/36) and hly (83.3%, 30/36). The strains were resistant to only 9 of the 14 antibiotics tested. The strains showed resistance in higher percentage to sulfamethoxazole/trimethoprim (STX/TMP: 38.8%, 14/36), penicillin (PE: 16.6%, 6/36), tetracycline (TE: 13.8%, 5/36) and amoxicillin/clavulanic acid (AMC: 13.8%, 5/36). The results of the current study show the presence of L. monocytogenes in cheese products sold in Tamaulipas, Mexico. The low prevalence of L. monocytogenes and low resistance to antibiotics could imply a low risk for public health. However, it is necessary to implement monitoring of L. monocytogenes in food, to monitor its potential risk for the consumer.
Usage of 150 mm Mueller - Hinton Agar for the EUCAST rapid antimicrobial susceptibility test (RAST) directly from positive blood culture bottles.
Yıldız SS, Şahin S, Tavukcu E … +4 more , Mumcuoğlu İ, Hekimoğlu CH, Güreser AS, Dal T
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40111424 · Publisher ↗
In this study, we evaluated the performance of modified rapid antimicrobial susceptibility test (mRAST) with 150 mm Mueller Hinton Agar (MHA) plates which was earlier standardized for 90 mm MHA by EUCAST. Blood culture b...
In this study, we evaluated the performance of modified rapid antimicrobial susceptibility test (mRAST) with 150 mm Mueller Hinton Agar (MHA) plates which was earlier standardized for 90 mm MHA by EUCAST. Blood culture bottles spiked with ATCC quality control strains were prepared. For quality control Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, and Enterococcus faecalis ATCC 29212 strains were used. By calculating and proportioning the surface areas of the plates comparing with 90 mm plates, 350 ± 50 µL undiluted blood culture samples were inoculated in 150 mm MHA, and 12 disks were placed. This process was repeated independently for three days and three times on each day for reproducibility. The mRAST test was performed on 50 samples with positive signals and gram-negative bacilli on Gram-stained samples (20 Klebsiella pneumoniae, 15 E. coli, 10 Acinetobacter baumannii, and five P. aeruginosa).Comparison of 90 mm MHA and 150 mm MHA showed that the categorical agreement of ATCC strains and 50 gram negative isolates was 100% and >95%, respectively, for all antibiotics. For K. pneumoniae, only 0.4 major error (ME) was detected at 4 h. For E. coli, 3.2, 1.6, and 1.5 ME were detected at 4, 8, and 20 h, respectively, whereas 1.6 very major error (VME) was detected at 4 h and 1.0 VME was detected at both 8, and 20 h, respectively. No errors were detected for P. aeruginosa or A. baumannii.These results indicated that 350 ± 50 µL of undiluted blood culture in 150 mm MHA was suitable for the mRAST test in vitro.
Detection of morphological variants of colistin-resistant Klebsiella pneumoniae associated with sepsis in Kerala, India.
Paul M, Thomas S
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40111416 · Publisher ↗
Infections caused by colistin resistant Klebsiella pneumoniae are a major global health challenge linked to high mortality rates worldwide. Increased incidence of hypervirulent and drug-resistant Klebsiella causing life-...
Infections caused by colistin resistant Klebsiella pneumoniae are a major global health challenge linked to high mortality rates worldwide. Increased incidence of hypervirulent and drug-resistant Klebsiella causing life-threatening infections in young healthy individuals and asymptomatic carriage in the community has been largely reported in the Asian-Pacific Rim. This study conducted a molecular analysis of two morphologically distinct variants of K. pneumoniae that caused bacteremia and sepsis in a patient. Colony morphology of the isolates was characterized in various growth media, and the morphological variants differed in their mucoviscosity. The isolates were found to be serotype K2 (highly associated with hypervirulent Klebsiella) by molecular serotyping using specific PCR primers. The multidrug-resistant nature of the colony variants was evaluated by antibiotic susceptibility testing and it was found to have a similar antibiogram pattern in in vitro. An increased minimum inhibitory concentration (MIC) of colistin (>64 μg mL-1) was detected in both isolates using broth microdilution, and they were found to be highly resistant to colistin. Molecular analysis revealed that the isolates possessed a chromosomal mutation in mgrB, which causes colistin resistance. The increased incidence of infection caused by colistin-resistant K. pneumoniae requires continuous monitoring, and appropriate measures are necessary to control its adaptive evolution in healthcare settings.
Corynebacterium propinquum: A confounding case of infective endocarditis.
Megdich Z, Ferjani A, Ferjani S … +4 more , Kanzari L, Fakhfakh A, Rehaiem A, Boutiba-Ben Boubaker I
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40085156 · Publisher ↗
Often dismissed as contaminants in blood cultures, Corynebacterium species can also cause infective endocarditis, a severe condition. We report an unusual case of Corynebacterium propinquum endocarditis in a non-immunoco...
Often dismissed as contaminants in blood cultures, Corynebacterium species can also cause infective endocarditis, a severe condition. We report an unusual case of Corynebacterium propinquum endocarditis in a non-immunocompromised individual on a native valve. Conflicting clinical and microbiological data led to 16S ribosomal sequencing to confirm the causative agent. Our case illustrates C. propinquum as a cause of infective endocarditis, and it demonstrates the utility of ancillary molecular diagnostic techniques to identify etiologic agents in difficult cases of infective endocarditis. C. propinquum should be recognized as a potential cause of infective endocarditis even on a native valve.
Periodontal pathogens as potential risk factors for systemic diseases: An overview.
Rao A, Kodangala S
Acta Microbiol Immunol Hung · 2025 Mar · PMID 40067380 · Publisher ↗
There is a plethora of evidence that suggests infection may either directly or indirectly trigger chronic inflammatory processes which may then act as a risk factor for diabetes mellitus and atherosclerosis. Inflammatory...
There is a plethora of evidence that suggests infection may either directly or indirectly trigger chronic inflammatory processes which may then act as a risk factor for diabetes mellitus and atherosclerosis. Inflammatory periodontal disease like periodontitis, is among the most prevalent oral infectious disease. It affects the tissues that support the teeth and has reportedly been linked to systemic conditions like diabetes mellitus and atherosclerosis. The onset and progression of periodontitis is significantly influenced by the plaque-biofilm and the host-inflammatory response to it. Evidence from numerous studies included in this review supports the hypothesis that there is an association between periodontal pathogens and systemic conditions like diabetes mellitus and atherosclerosis. An overview of some of the periodontal pathogens associated with periodontitis and the proposed mechanisms by which these pathogens can evade and invade the human defence system triggering the onset of chronic diseases like diabetes mellitus and atherosclerosis are presented in this article.
In vitro activity of ceftazidime-avibactam, ceftolozane-tazobactam, imipenem-relebactam, meropenem-vaborbactam and cefiderocol against carbapenemase-producing Enterobacterales from clinical isolates in a tertiary healthcare centre in Serbia.
Mladenović-Antić S, Veličković-Radovanović R, Stojanović P … +2 more , Randjelović M, Djordjević V
Acta Microbiol Immunol Hung · 2025 Mar · PMID 39969523 · Publisher ↗
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-taz...
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.
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