Diffusion of OXA-48 carbapenemase among urinary isolates of Klebsiella pneumoniae in non-hospitalized elderly patients

Characterization of Klebsiella pneumoniae Isolates Resistant to Cefiderocol from Hospitals and Outpatient Settings in Croatia

BACKGROUND/OBJECTIVES

We conducted this study to evaluate the genotypic and phenotypic profiles of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates, exhibiting resistance to cefiderocol (FDC), focusing on antibiotic susceptibility, β-lactamase production, the genetic environment of blaCARB and blaESBL genes and molecular epidemiology. FDC is now a last-line antibiotic for severe infections due to CRKP.

METHODS

Susceptibility to a wide range of antibiotics was determined by the disk diffusion and broth microdilution method. Carbapenemases were screened by a modified Hodge test while carbapenem hydrolysis was investigated using mCIM and eCIM tests. The screening for β-lactamase and fluoroquinolone cluster resistance genes was carried out by PCR. Plasmids were characterized by PCR-based replicon typing (PBRT). An inter-array genotyping CarbaResist test and whole genome sequencing (WGS) were applied on selected isolates.

RESULTS

All of the 31 isolates studied exhibited high-level resistance to amoxicillin-clavulanate, piperacillin-tazobactam, cefuroxime, expanded-spectrum cephalosporins (ESC), cefepime, ceftolozan-tazobactam and ciprofloxacin and the majority to gentamicin, and amikacin. Colistin and ceftazidime-avibactam preserved activity against 71% and 87% of the isolates, respectively. The combined disk method with clavulanic acid was positive in all but one isolate, indicating the production of an ESBL. Twenty-eight isolates carried one single carbapenemase-encoding gene, whereas three harbored double blaCARB genes. Among the studied isolates, 61% carried blaOXA-48, 29% blaKPC and 12.9% blaNDM genes. The inter-array genotyping CarbaResist test and WGS identified additional aminoglycoside-, sulphonamide- and trimethoprim-resistance genes.

CONCLUSION

To our knowledge, this is the first study on FDC resistance in Croatia. The diffusion of FDC-resistant isolates was detected in both hospital and outpatient settings, emphasizing the need for a "One Health" approach.

Molecular detection of OXA-48 and NDM-1 carbapenemase genes among clinical isolates of Klebsiella pneumoniae recovered from patients attending a private tertiary hospital in Southwestern Nigeria

There have been increasing reports of Klebsiella pneumoniae resistant to β-lactam antibiotics. This study aimed to determine the prevalence of some selected carbapenemase genes among clinical isolates of Klebsiella pneumoniae recovered from patients attending a private tertiary hospital in Southwestern Nigeria. The study was conducted over two months (February-March 2024). A total of 50 clinical isolates of Klebsiella pneumoniae from different clinical specimens were obtained from the Medical Microbiology Department, Babcock University Teaching Hospital (BUTH). The clinical isolates were then characterized using standard microbiological procedures and were tested for susceptibility to meropenem and other classes of antibiotics according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Polymerase Chain Reaction (PCR) detection for OXA-48 and NDM-1 carbapenemase genes was performed on the 50 clinical isolates. PCR analysis showed that 9 (18%) clinical isolates were positive for the OXA-48 gene, 22 (44%) were positive for the NDM-1 gene, 4 (8%) possessed both the OXA-48 and NDM-1 genes, and 23 (46%) possessed neither the OXA-48 nor NDM-1 genes. Antibiotic Susceptibility Testing (AST) revealed that all the clinical isolates were resistant to meropenem. In conclusion, this study demonstrates the presence of OXA-48 and NDM-1 genes in clinical isolates of Klebsiella pneumoniae recovered from patients attending a private tertiary hospital in Southwestern Nigeria, highlighting the role of ESBL (extended-spectrum beta-lactamase) as a major resistance mechanism alongside other mechanisms. Population-based surveillance programs should be implemented to monitor the prevalence and epidemiology of Klebsiella pneumoniae infections at the community level, facilitating early detection of outbreaks and identification of emerging antimicrobial resistance patterns. CORE TIP: This study highlights the significant prevalence of NDM-1 and OXA-48 carbapenemase genes among Klebsiella pneumoniae clinical isolates in a private tertiary hospital in Southwestern Nigeria, with 44% and 18% of isolates harboring these genes, respectively. Notably, 46% of isolates were resistant to carbapenems despite lacking these genes, suggesting alternative resistance mechanisms. The findings underscore the urgent need for enhanced surveillance, infection control measures, and antibiotic stewardship programs to combat the spread of multidrug-resistant Klebsiella pneumoniae in healthcare settings.

Complete genome sequence of the OXA-48-producing Klebsiella pneumoniae strain 11978

We announce the complete genome sequence of Klebsiella pneumoniae strain 11978 isolated from a patient hospitalized in Turkey in 2001. The genome belongs to sequence type 14 and includes three plasmids. Notably, it presents an IncL plasmid carrying blaOXA-48, which demonstrated global success in terms of dissemination.

Different OXA-Carbapenemases in Genetically Unrelated Klebsiella pneumoniae Strains Isolated in a North Italian Hospital During Multidrug Resistance Screening

Klebsiella pneumoniae is one of the main opportunistic pathogens that cause a broad spectrum of diseases with increasingly frequent acquisition of resistance to antibiotics, namely carbapenems. This study focused on the characterization of 23 OXA-48-like carbapenemase-producing K. pneumoniae isolates using phenotypic and molecular tests. Phenotypic determination of the presence of β-lactamases was performed using the extended-spectrum beta-lactamase (ESBL) NP test, and phenotypic determination of the presence of carbapenemase was based on the Carba NP test. Antimicrobial susceptibility tests were performed to assess the resistance against carbapenems. Molecular characterization of ESBL genes and carbapenemase genes (blaOXA-48, blaKPC, blaVIM, and blaNDM) was performed using polymerase chain reaction (PCR) techniques. In addition, K. pneumoniae strains were analyzed for their relatedness using multilocus sequence typing PCR analysis based on the Institut Pasteur protocol, which produces allelic profiles that contain their evolutionary and geographic pattern. Following further Sanger sequencing of the blaOXA-48 genes, no genetic mutations were found. Some OXA-48-producing K. pneumoniae isolates coharbored blaKPC, blaNDM, and blaVIM genes, which encode other carbapenemases that can hydrolyze carbapenem antibiotics. The final part of the study focused on the characterization of the plasmid profiles of all isolates to better understand the spreading of the IncL/M blaOXA-48 plasmid gene. The plasmid profile also revealed other incompatibility groups, suggesting that other plasmid genes are spreading in K. pneumoniae isolates, which can coharbor and spread different carbapenemases simultaneously.

Molecular epidemiology and mechanisms of carbapenem and colistin resistance in Klebsiella and other Enterobacterales from treated wastewater in Croatia

Among the most problematic bacteria with clinical relevance are the carbapenem-resistant Enterobacterales (CRE), as there are very limited options for their treatment. Treated wastewater can be a route for the release of these bacteria into the environment and the population. The aim of this study was to isolate CRE from treated wastewater from the Zagreb wastewater treatment plant and to determine their phenotypic and genomic characteristics. A total of 200 suspected CRE were isolated, 148 of which were confirmed as Enterobacterales by MALDI-TOF MS. The predominant species was Klebsiella spp. (n = 47), followed by Citrobacter spp. (n = 40) and Enterobacter cloacae complex (cplx.) (n = 35). All 148 isolates were carbapenemase producers with a multidrug-resistant phenotype. Using multi-locus sequence typing and whole-genome sequencing (WGS), 18 different sequence types were identified among these isolates, 14 of which were associated with human-associated clones. The virulence gene analysis of the sequenced Klebsiella isolates (n = 7) revealed their potential pathogenicity. PCR and WGS showed that the most frequent carbapenemase genes in K. pneumoniae were blaOXA-48 and blaNDM-1, which frequently occurred together, while blaKPC-2 together with blaNDM-1 was mainly detected in K. oxytoca, E. cloacae cplx. and Citrobacter spp. Colistin resistance was observed in 40% of Klebsiella and 57% of Enterobacter isolates. Underlying mechanisms identified by WGS include known and potentially novel intrinsic mechanisms (point mutations in the pmrA/B, phoP/Q, mgrB and crrB genes) and acquired mechanisms (mcr-4.3 gene). The mcr-4.3 gene was identified for the first time in K. pneumoniae and is probably located on the conjugative IncHI1B plasmid. In addition, WGS analysis of 13 isolates revealed various virulence genes and resistance genes to other clinically relevant antibiotics as well as different plasmids possibly associated with carbapenemase genes. Our study demonstrates the important role that treated municipal wastewater plays in harboring and spreading enterobacterial pathogens that are resistant to last-resort antibiotics.

Bloodstream Infections by AmpC-Producing Enterobacterales: Risk Factors and Therapeutic Outcome

Bloodstream infections associated with AmpC-producing Enterobacterales are severe medical conditions which, without prompt and effective treatment, may have dire ramifications. This study aimed to assess whether certain comorbidities and previous surgical procedures coincide with resistance determinants of AmpC-producing Enterobacterales associated with bloodstream infections. Antibiotic resistance patterns and therapy outcome were also determined. The patients' data obtained revealed that the prevalence of recent surgical procedures, solid organ tumors, metabolic diseases, kidney and liver failure, and hematological malignancies do not differ between resistant and susceptible isolates of AmpC-producing Enterobacterales. Furthermore, no difference was reported in mortality rates. Regarding antibiotic resistance, 34.52% of isolates were confirmed to be resistant (AmpC hyperproduction, ESBL, or carbapenemase). More than one in five AmpC hyperproducers were reported amid Providencia spp., K. aerogenes, E. cloacae, and C. freundii. strains. Carbapenemases were mostly noted in Providencia spp. followed by M. morganii and K. aerogenes strains. Serratia marcescens had the highest proportion of ESBLsof ESBLs. Resistance to expanded-spectrum cephalosporins of Providencia spp. and K. aerogenes strains exceeded 50%, and resistance to meropenem over 10% was observed only in C. freundii strains. Enterobacterales' ever-growing resistance to antibiotics is becoming quite a challenge for clinicians and new treatment options are required.

The burden of bacterial antimicrobial resistance in Croatia in 2019: a country-level systematic analysis

AIM

To deliver the most wide-ranging set of antimicrobial resistance (AMR) burden estimates for Croatia to date.

METHODS

A complex modeling approach with five broad modeling components was used to estimate the disease burden for 12 main infectious syndromes and one residual group, 23 pathogenic bacteria, and 88 bug-drug combinations. This was represented by two relevant counterfactual scenarios: deaths/disability-adjusted life years (DALYs) that are attributable to AMR considering a situation where drug-resistant infections are substituted with sensitive ones, and deaths/DALYs associated with AMR considering a scenario where people with drug-resistant infections would instead present without any infection. The 95% uncertainty intervals (UI) were based on 1000 posterior draws in each modeling step, reported at the 2.5% and 97.5% of the draws' distribution, while out-of-sample predictive validation was pursued for all the models.

RESULTS

The total burden associated with AMR in Croatia was 2546 (95% UI 1558-3803) deaths and 46958 (28,033-71,628) DALYs, while the attributable burden was 614 (365-943) deaths and 11321 (6,544-17,809) DALYs. The highest number of deaths was established for bloodstream infections, followed by peritoneal and intra-abdominal infections and infections of the urinary tract. Five leading pathogenic bacterial agents were responsible for 1808 deaths associated with resistance: Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa (ordered by the number of deaths). Trimethoprim/sulfamethoxazole-resistant E coli and methicillin-resistant S. aureus were dominant pathogen-drug combinations in regard to mortality associated with and attributable to AMR, respectively.

CONCLUSION

We showed that AMR represented a substantial public health concern in Croatia, which reflects global trends; hence, our detailed country-level findings may fast-track the implementation of multipronged strategies tailored in accordance with leading pathogens and pathogen-drug combinations.

Anti-Klebsiella pneumoniae activity of secondary metabolism of Achromobacter from the intestine of Periplaneta americana

BACKGROUND

Klebsiella pneumoniae is one of the main pathogens of clinical isolation and nosocomial infections, as K. pneumoniae show broad-spectrum resistance to β-lactam and carbapenem antibiotics. It is emerging clinical need for a safe and effective drug to anti-K. pneumoniae. At present, Achromobacter mainly focused on its degradation of petroleum hydrocarbons, polycyclic aromatic hydrocarbons, assisting insects to decompose, degrade heavy metals and utilize organic matter, but there were few reports on the antibacterial activity of the secondary metabolites of Achromobacter.

RESULTS

In this study, a strain WA5-4-31 from the intestinal tract of Periplaneta americana exhibited strong activity against K. Pneumoniae through preliminary screening. The strain was determined to be Achromobacter sp. through the morphological characteristics, genotyping and phylogenetic tree analysis, which is homologous to Achromobacter ruhlandii by 99%, its accession numbe in GenBank at National Center for Biotechnology Information (NCBI) is MN007235, and its deposit number was GDMCC NO.1.2520. Six compounds (Actinomycin D, Actinomycin X2, Collismycin A, Citrinin, Neoechinulin A and Cytochalasin E) were isolated and determined by activity tracking, chemical separation, nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis. Among them, Actinomycin D, Actinomycin X2, Collismycin A, Citrinin and Cytochalasin E showed a good effect on anti-K. pneumoniae, with MIC values of 16-64 µg/mL.

CONCLUSIONS

The study reported Achromobacter, which was from the intestinal tract of Periplaneta americana with the activity against K. Pneumoniae, can produce antibacterial compounds for the first time. It lays the foundation for development of secondary metabolites of insect intestinal microorganisms.

Emergence and Spread of Enterobacterales with Multiple Carbapenemases after COVID-19 Pandemic

Resistance to carbapenems in Enterobacterales has become a matter of the highest concern in the last decade. Recently, Enterobacterales harboring multiple carbapenemases were detected in three hospital centers in Croatia and in the outpatient setting, posing a serious therapeutic challenge for clinicians. In this study, we analyzed eight Klebsiella pneumoniae and two Enterobacter cloacae complex isolates with multiple carbapenemases, with regard to antibiotic susceptibility, β-lactamase production and plasmid content. The isolates demonstrated uniform resistance to amoxicillin/clavulanate, piperacillin/tazobactam, cefuroxime, ceftazidime, cefotaxime, ceftriaxone and ertapenem. Among novel β-lactam/inhibitor combinations, ceftazidime/avibactam exhibited moderate activity, with 50% of isolates susceptible. All isolates demonstrated resistance to imipenem/cilastatin/relebactam, and all but one to ceftolozane/tazobactam. Four isolates exhibited a multidrug-resistant phenotype (MDR), whereas six were allocated to an extensively drug-resistant phenotype (XDR). OKNV detected three combinations of carbapenemases: OXA-48+NDM (five isolates), OXA-48+VIM (three isolates) and OXA-48+KPC (two isolates). Inter-array testing identified a wide variety of resistance genes for β-lactam antibiotics: bla_CTX-M-15, bla_TEM, bla_SHV, bla_OXA-1, bla_OXA-2, bla_OXA-9, aminoglycosides: aac6, aad, rmt, arm and aph, fluoroquinolones: qnrA, qnrB and qnrS, sulphonamides: sul1 and sul2 and trimethoprim: dfrA5, dfrA7, dfrA14, dfrA17 and dfrA19. mcr genes were reported for the first time in Croatia. This study demonstrated the ability of K. pneumoniae and E. cloacae to acquire various resistance determinants under the selection pressure of antibiotics widely used during the COVID-19 pandemic. The novel inter-array method showed good correlation with OKNV and PCR, although some discrepancies were found.

Exploring the Antibiotic Resistance Profile of Clinical Klebsiella pneumoniae Isolates in Portugal

While antibiotic resistance is rising to dangerously high levels, resistance mechanisms are spreading globally among diverse bacterial species. The emergence of antibiotic-resistant Klebsiella pneumoniae, mainly due to the production of antibiotic-inactivating enzymes, is currently responsible for most treatment failures, threatening the effectiveness of classes of antibiotics used for decades. This study assessed the presence of genetic determinants of β-lactam resistance in 102 multi-drug resistant (MDR) K. pneumoniae isolates from patients admitted to two central hospitals in northern Portugal from 2010 to 2020. Antimicrobial susceptibility testing revealed a high rate (>90%) of resistance to most β-lactam antibiotics, except for carbapenems and cephamycins, which showed antimicrobial susceptibility rates in the range of 23.5−34.3% and 40.2−68.6%, respectively. A diverse pool of β-lactam resistance genetic determinants, including carbapenemases- (i.e., blaKPC-like and blaOXA-48-like), extended-spectrum β-lactamases (ESBL; i.e., blaTEM-like, blaCTX-M-like and blaSHV-like), and AmpC β-lactamases-coding genes (i.e., blaCMY-2-like and blaDHA-like) were found in most K. pneumoniae isolates. blaKPC-like (72.5%) and ESBL genes (37.3−74.5%) were the most detected, with approximately 80% of K. pneumoniae isolates presenting two or more resistance genes. As the optimal treatment of β-lactamase-producing K. pneumoniae infections remains problematic, the high co-occurrence of multiple β-lactam resistance genes must be seen as a serious warning of the problem of antimicrobial resistance.