High diversity of beta-lactamases in the General Hospital Vienna verified by whole genome sequencing and statistical analysis

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.

Virulence Factor Genes in Invasive Escherichia coli Are Associated with Clinical Outcomes and Disease Severity in Patients with Sepsis: A Prospective Observational Cohort Study

BACKGROUND

Escherichia coli harbours virulence factors that facilitate the development of bloodstream infections. Studies determining virulence factors in clinical isolates often have limited access to clinical data and lack associations with patient outcome. The goal of this study was to correlate sepsis outcome and virulence factors of clinical E. coli isolates in a large cohort.

METHODS

Patients presenting at the emergency department whose blood cultures were positive for E. coli were prospectively included. Clinical and laboratory parameters were collected at admission. SOFA-score was calculated to determine disease severity. Patient outcomes were in-hospital mortality and ICU admission. Whole genome sequencing was performed for E. coli isolates and virulence genes were detected using the VirulenceFinder database.

RESULTS

In total, 103 E. coli blood isolates were sequenced. Isolates had six to 41 virulence genes present. One virulence gene, kpsMII_K23, a K1 capsule group 2 of E. coli type K23, was significantly more present in isolates of patients who died. kpsMII_K23 and cvaC (Microcin C) were significantly more frequent in isolates of patients who were admitted to the ICU. Fourteen virulence genes (mchB, mchC, papA_fsiA_F16, sat, senB, iucC, iutA, iha, sfaD, cnf1, focG, vat, cldB, and mcmA) significantly differed between patients with and without sepsis.

CONCLUSIONS

Microcins, toxins, and fimbriae were associated with disease severity. Adhesins and iron uptake proteins seemed to be protective. Two genes were associated with worse clinical outcome. These findings contribute to a better understanding of host-pathogen interactions and could help identifying patients most at risk for a worse outcome.

Resistance to critically important antibiotics in hospital wastewater from the largest Croatian city

The emergence of extended-spectrum β-lactamase (ESBL)- and especially carbapenemases in Enterobacterales has led to limited therapeutic options. Therefore, it is critical to fully understand all potential routes of transmission, especially in high-risk sources such as hospital wastewater. This study aimed to quantify four enteric opportunistic pathogens (EOPs), total, ESBL- and carbapenem-resistant coliforms and their corresponding resistance genes (two ESBL and five carbapenemase genes) and to characterize enterobacterial isolates from hospital wastewater from two large hospitals in Zagreb over two seasons. Culturing revealed similar average levels of total and carbapenem-resistant coliforms (3.4 × 10⁴ CFU/mL), and 10-fold lower levels of presumptive ESBL coliforms (3 × 10³ CFU/mL). Real-time PCR revealed the highest E. coli levels among EOPs (10⁵ cell equivalents/mL) and the highest levels of the bla_KPC gene (up to 10^-1 gene copies/16S copies) among all resistance genes examined. Of the 69 ESBL- and 90 carbapenemase-producing Enterobacterales (CPE) isolates from hospital wastewater, all were multidrug-resistant and most were identified as Escherichia coli, Citrobacter, Enterobacter, and Klebsiella. Among ESBL isolates, bla_CTX-M-15 was the most prevalent ESBL gene, whereas in CPE isolates, bla_KPC-2 and bla_NDM-1 were the most frequently detected CP genes, followed by bla_OXA-48. Molecular epidemiology using PFGE, MLST and whole-genome sequencing (WGS) revealed that clinically relevant variants such as E. coli ST131 (bla_CTX-M-15/bla_TEM-116) and ST541 (bla_KPC-2), K. pneumoniae ST101 (bla_OXA-48/bla_NDM-1), and Enterobacter cloacae complex ST277 (bla_KPC-2/bla_NDM-1) were among the most frequently detected clone types. WGS also revealed a diverse range of resistance genes and plasmids in these and other isolates, as well as transposons and insertion sequences in the flanking regions of the bla_CTX-M, bla_OXA-48, and bla_KPC-2 genes, suggesting the potential for mobilization. We conclude that hospital wastewater is a potential secondary reservoir of clinically important pathogens and resistance genes and therefore requires effective pretreatment before discharge to the municipal sewer system.

Analysis of Extended Spectrum Beta Lactamase (ESBL) Genes of Non-Invasive ESBL Enterobacterales in Southeast Austria in 2017

Extended spectrum beta lactamases producing Enterobacteriaceae are a major player in the antibiotic resistance challenge. In general, the situation regarding antibiotic resistance in Austria is very good compared to many other countries. Perhaps this is why there is a lack of data on the distribution of ESBL genes in the clinical setting. The aim of this study was to collect data on ESBL genes from a larger sample of human non-invasive clinical isolates from one region in Austria. In total, 468 isolates from different sample materials isolated at the Medical University of Graz from 2017 were examined. The most frequent organisms were Escherichia coli and Klebsiella pneumoniae. Among the enzymes produced, CTX-M-15 was clearly dominant, exotic ESBLs were only represented by three Proteus mirabilis isolates harboring genes for VEB-6 and one P. mirabilis for CTX-M-2, respectively. Compared to other countries, the results are in line with the expectations. The data help to better classify the many studies from the non-clinical field in Austria and to shift the focus slightly away from the exotic results and sample sites.

Proteus mirabilis harboring carbapenemase NDM-5 and ESBL VEB-6 detected in Austria

We describe a case of carbapenemase-harboring Proteus mirabilis together with detection of NDM-5 in Austria accompanied by other bacterial strains with a wide range of beta-lactamases including OXA-181 and VEB-6. Isolates were obtained from a subphrenic abscess from one patient who was previously treated with broad-spectrum antibiotics in Bangladesh.

Troubled water under the bridge: Screening of River Mur water reveals dominance of CTX-M harboring Escherichia coli and for the first time an environmental VIM-1 producer in Austria

Antibiotic resistant bacteria (ARB) in the aquatic environment are reported from all over the world and their presence in the environment has become quite common. The current most prominent example is the presence of beta-lactamases harboring Enterobacteriaceae. The aim of this study was to investigate the presence and diversity (on the genetic and phenotypic levels) of extended spectrum beta-lactamases (ESBL) and carbapenemases harboring Enterobacteriaceae from the River Mur in the center of Graz, Austria's second largest city. Thus over a period of four months water samples were taken, filtrated and screened for these bacteria. All samples revealed ESBL harboring Enterobacteriaceae, of which all with only one exception were Escherichia coli. Dominant ESBL gene family was CTX-M, represented by subgroups CTX-M-1 group, CTX-M-2 group and CTX-M-9 group. Surprisingly co-resistances to non-beta-lactam antibiotics were low, only resistance to trimethoprim was detected in 50% of all (70) isolates. One Klebsiella oxytoca with GES-1 was isolated. To date, GES ESBL has never been reported from Austria before and only rarely from other European countries. Screening for carbapenemase harboring Enterobacteriaceae revealed one Enterobacter cloacae with the gene for VIM-1. Members sharing the same multi-locus-sequence-type (MLST) as well as members of the same rep PCR clusters occurred at different sampling time points. ESBL-harboring Enterobacteriaceae are common in Austrian river water, is dominated by Escherichia coli and CTX-M enzymes. Furthermore, some of the isolates could be linked to different origins.

Multiplex characterization of human pathogens including species and antibiotic-resistance gene identification

The efficient medical treatment of infections requires detailed information about the pathogens involved and potential antibiotic-resistance mechanisms. The dramatically increasing incidence of multidrug-resistant bacteria especially highlights the importance of sophisticated diagnostic tests enabling a fast patient-customized therapy. However, the current molecular detection methods are limited to either the detection of species or only a few antibiotic-resistance genes.In this work, we present a human pathogen characterization assay using a rRNA gene microarray identifying 75 species comprising bacteria and fungi. A statistical classifier was developed to facilitate the automated species identification. Additionally, the clinically most important β-lactamases were identified simultaneously in a 100-plex reaction using padlock probes and the same microarray. The specificity and sensitivity of the combined assay was determined using clinical isolates. The detection limit was 10(5) c.f.u. ml(-1), recovering 89 % of the detectable β-lactamase-encoding genes specifically. The total assay time was less than 7 hand the modular character of the antibiotic-resistance detection allows the easy integration of further genetic targets. In summary, we present a fast, highly specific and sensitive multiplex pathogen characterization assay.