Enterobacter asburiae ST229: an emerging carbapenemases producer

Enterobacter asburiae, member of the Enterobacter cloacae complex (ECC) group, shows an increasing clinical relevance being responsible for infections like pneumonia, urinary tract infections and septicemia. The aim of the present study was the investigation of the genomic features of two XDR E. asburiae ST229 clinical strains co-carrying blaNDM-1 and blaVIM-1 determinants, collected in October 2021 and in June 2022, respectively. Two E. asburiae strains were collected from rectal swabs of as many patients admitted to the cardiopulmonary intensive care unit of Fondazione I.R.C.C.S. "Policlinico San Matteo" in Pavia, Italy. Based on the antibiotic susceptibility profile results, both isolates showed an XDR phenotype, retaining susceptibility only to fluoroquinolones. Both isolates shared identical resistome, virulome, plasmid content, and belonged to ST229, a rarely reported sequence type. They co-harbored blaNDM-1 and blaVIM-1 genes, that resulted located on transferable plasmids by conjugation and transformation. Moreover, both strains differed in 24 SNPs and showed genetic relatedness with E. asburiae ST709 and ST27. We described the first case of ST229 E. asburiae co-harboring blaNDM-1 and blaVIM-1 in Italy. This study points out the emergence of carbapenemases in low-risk pathogens, representing a novel challenge for public health, that should include such types of strains in dedicated surveillance programs. Antimicrobial susceptibility testing was carried out using Thermo Scientific™ Sensititre™ Gram Negative MIC Plates DKMGN. Both strains underwent whole-genome sequencing (WGS) using Illumina Miseq platform. Resistome, plasmidome, virulome, MLST, plasmid MLST and a SNPs-based phylogenetic tree were in silico determined.

Risk factors associated with colistin resistance in carbapenemase-producing Enterobacterales: a multicenter study from a low-income country

PURPOSE

The aim of this study was to assess the risk factors for colistin-resistant carbapenemase-producing Enterobacterales (CR-CPE), and describe the mortality associated with this organism, in a low-income country.

METHODS

A descriptive, observational, and prospective multicenter study was carried out in Guayaquil, Ecuador. All patients with carbapenem-resistant Enterobacterales admitted between December 2021 and May 2022 were enrolled. Infection definitions were established according to the Centers for Disease Control and Prevention (CDC) protocols. The presence of carbapenemase-producing Enterobacterales was confirmed with a multiplex PCR for blaKPC, blaNDM, blaOXA-48, blaVIM, and blaIMP genes. MCR-1 production was studied molecularly, and MLST assays were carried out.

RESULTS

Out of 114 patients enrolled in the study, 32 (28.07%) had at least one positive sample for CR-CPE. Klebsiella pneumoniae ST512-KPC-3 was the most frequent microorganism isolated. Parenteral feeding, β-lactamase inhibitor use, recent hemodialysis, and renal failure were all considered independent risk factors for carrying CR-CPE. A mortality of 41.22% was detected, but we could not find any difference between colistin-resistant and colistin-susceptible CPE. MCR-1 production was not detected in any of the isolates studied.

CONCLUSION

A significant burden for CR-CPE was found in a South American country that was mainly caused by the high-risk clone K. pneumoniae ST512-KPC-3 and not mediated by mcr-1 production. Its acquisition involved parenteral feeding, β-lactamase inhibitor use, recent hemodialysis, and renal failure as independent risk factors, demonstrating the critical need for infection prevention and stewardship programs to avoid dissemination to other countries in the region.

Risk factors for acquisition of carbapenemase-producing versus non-carbapenemase-producing enterobacterales: a case-control study

OBJECTIVES

We aimed to assess the association between carbapenem-resistant Enterobacterales (CRE) colonization pressure and carbapenem exposure and acquisition of carbapenemase-producing Enterobacterales (CPE) and non-carbapenemase-producing carbapenem-resistant Enterobacterales (non-CP-CRE).

METHODS

We conducted a parallel 1:2 matched case-control study at Rambam Health Care Campus, Israel, from January 2014 to June 2017. The cases included all adults who acquired CPE or non-CP-CRE in hospital. The controls were hospitalized patients who were negative for CRE on screening and matched by age, hospitalization division and the number of hospitalization days 90 days prior to CRE screening. The exposures of interest were high CRE colonization pressure, defined as a higher-than-median proportion of CRE carriers in the concurrent patient's department before acquisition, and carbapenem exposure, assessed as days of treatment. Conditional logistic regression was used for analyses of CPE and non-CP-CRE.

RESULTS

In total, 1058 patients were included: 278 CPE and 75 non-CP-CRE cases, matched to 556 and 149 controls, respectively. High CRE colonization pressure was associated with CPE acquisition (adjusted odds ratio [aOR], 2.6; 95% CI, 1.69-4.02); however, the duration of carbapenem treatment was not (aOR, 1.004; 95% CI, 0.98-1.03; 1-day increment). The duration of carbapenem treatment was significantly associated with non-CP-CRE acquisition (aOR per day, 1.07; 95% CI, 1.03-1.11). A source patient was identified significantly more frequently in epidemiological acquisition investigations of CPE than in those of non-CP-CRE (107/240, 44.6% vs. 18/64, 28.1%, respectively; p 0.017).

CONCLUSIONS

CPE acquisition was associated with horizontal transmission, whereas non-CP-CRE was associated with carbapenem exposure. Differences in the drivers of acquisition mandate tailored infection prevention efforts.

Healthcare workers' experiences of caring for patients colonized with carbapenemase-producing Enterobacterales (CPE) in an acute hospital setting - a scoping review

Carbapenemase-producing Enterobacterales (CPE) is an increasing public health concern; these bacteria are highly transmissible in hospital environments and the number of patients with these multidrug-resistant bacteria is rising. Healthcare workers caring for patients colonized with CPE offer insight into care delivery and processes in the hospital setting. The aim of this review was to explore healthcare workers' experiences of caring for patients colonized with CPE. A scoping review method was employed and seven electronic databases (CINAHL, Academic Search Complete, Cochrane, Embase, Medline, Web of Science and Scopus) and four grey literature databases (Open Grey, Grey Literature Report, Clinical trials. gov and WHO International Clinical Trials Registry Platform) were searched using specific search terms and inclusion/exclusion criteria. A PRISMA flow diagram was used to illustrate the process of article selection and thematic analysis used to form themes. Three studies met the criteria to be included in this review. Two main themes were identified from analysing the articles: 'Safeguarding' and 'Power of Knowledge'. The desire to protect themselves, their families and patients was evident from the studies. Healthcare workers were aware of the importance on infection prevention and control measures such as hand hygiene, in preventing the transmission of CPE, however barriers to these were identified, such as time constraints. In conclusion, healthcare workers have negative associations when it comes to caring for patients with CPE. Very little research has been conducted in the area and there is an opportunity to further explore the experience of healthcare workers caring for patients with CPE to identify opportunities for improvement and support of staff.

A geographic cluster of healthcare-associated carbapenemase-producing hypervirulent Klebsiella pneumoniae sequence type 23

Hypervirulent Klebsiella pneumoniae has typically been associated with invasive, community-associated infections. This study describes the molecular, epidemiological and clinical characteristics of a cluster of carbapenemase-producing hypervirulent K. pneumoniae in the South-East of Ireland. It highlights the increasing risk that hypervirulent K. pneumoniae poses to healthcare and residential care populations. A retrospective analysis of sequences on K. pneumoniae isolates in the K. pneumoniae database of the National Carbapenemase-Producing Enterobacterales Reference Laboratory Service was performed to identify cases of hypervirulent K. pneumoniae from one hospital network. Hypervirulence scores were assigned based on the presence of recognised hypervirulence genes. A retrospective review of patient records was carried out for all confirmed cases of hypervirulent K. pneumoniae identified and clinical, epidemiological and molecular characteristics described. Twenty-eight cases of hypervirulent OXA-48 producing K. pneumoniae were identified over a 2-year period. All isolates were sequence-type 23 with a hypervirulence score of 5. All isolates carried the blaOXA-48 carbapenemase gene. All cases had a record of current or recent hospitalisation or residence in a long-term residential care facility. This study describes extensive dissemination of hypervirulent K. pneumoniae within healthcare facilities and an ongoing outbreak in our region. It shows the convergence of hypervirulence and antibiotic resistance determinants. Healthcare facilities need to consider their infection prevention, control and surveillance strategies to monitor and prevent further dissemination among a vulnerable population. Diagnostic laboratories need to ensure they have the ability and capacity for testing. Readily deployed laboratory methods for detection of hypervirulence are required.

Epidemiology and clinical characteristics of infection/colonization due to carbapenemase-producing Enterobacterales in neonatal patients

Background

The aim of this study was to elucidate the epidemiological features of carbapenemase-producing Enterobacterales (CPE) in the pediatric and neonatal patients, to describe clinical characteristics of neonatal patients with CPE infections, and to assess risk factors for neonatal rectal colonization with CPE.

Results

A total of 439 carbapenem-resistant Enterobacterales (CRE) isolates recovered from 367 infant patients were characterised, including 397 isolates of Klebsiella pneumoniae (KP) and 42 isolates of Escherichia coli (EC). Carbapenemase gene blaNDM-1 was the most commonly detected, accounting for 86.56% (n = 380), followed by blaKPC-2 (9.11%, 40) and blaIMP-4 (4.33%, 19). MLST analysis showed 17 different STs detected within CPKP isolates, with ST20, ST2068, ST36 and ST17 being the most frequently isolated types. Eleven STs were identified within CPEC isolates, with ST325 being the dominant types. Eight isolates of NDM-1 producing KP, belonging to ST23, were identified as having hypervirulent traits. The main infections caused by CPE were pneumonia (n = 90) and sepsis (n = 16). All infected patients received monotherapy, with meropenem and ciprofloxacin being the most commonly used antibiotics. All pneumonia patients were cured or improved after treatment. Of the 16 patients with sepsis, 9 were cured or improved, 3 died, and 4 abandoned treatment without any clinical improvement. The rectal prevalences of CPE in the 0–3 days old (DO), the 4–28 DO, and the 29 DO-1 year old groups were decreased from 15.31%, 27.37% and 14.29% in the first stool screening period to 11.78%, 19.59% and 4.07% in the second stool screening period, respectively. Multivariate analysis showed that cesarean section, acidosis, respiration failure, gastric lavage and enema were independent risk factors for rectal colonization in the 0–3 DO group, whereas cesarean section, cephalosporins, gastric lavage and residence in rural area were independently associated with rectal colonization in the 4–28 DO group. The implementation of a series of evidence-based control measures eventually contained the CPE transmission.

Conclusions

Continued vigilance, epidemiological studies, and multimodal infection prevention strategies are urgently needed due to frequent importations.

Transfer of plasmids harbouring blaOXA-48-like carbapenemase genes in biofilm-growing Klebsiella pneumoniae: Effect of biocide exposure

The spread of OXA-48-encoding plasmids from Klebsiella pneumoniae (OXA-48-Kpn), especially successful high-risk (HR) clones, is a growing concern. Biofilm formation can contribute to the dissemination of OXA-48-Kpn. It is not known whether biocides can affect the transfer of OXA-48-Kpn in biofilm. The aim of this study was to evaluate the effect of biocides on the conjugation frequency (CF) of OXA-48-Kpn in both biofilm and planktonic cultures. For that, seven OXA-48-Kpn isolates (4 belonging to HR clones and 3 to non-HR clones) were selected as donors. Each isolate was mixed (1:1) with Escherichia coli J53 (recipient) and grown on polystyrene microplates without biocides (control) and with 0.25x MIC of triclosan (TRI), chlorhexidine digluconate (CHX), povidone-iodine (POV), sodium hypochlorite (SOD) or ethanol (ETH). The CF was calculated as the number of transconjugants/number of E. coli J53. The results showed that for isolates growing in the absence of biocide, the mean fold change in the CF in biofilm with respect to that determined in planktonic cells (CF-BF/CF-PK) was 0.2 in non-HR isolates and ranged from 2.0 to 14.7 in HR isolates. In HR isolates grown in the presence of biocide, especially CHX, TRI, and ETH, the fold changes in CF-BF/CF-PK decreased, whereas in non-HR isolates the fold changes were similar or increased slightly with CHX, ETH, SOD and POV. In conclusion, the fold changes in the CF-BF/CF-PK are higher in HR isolates comparing to non-HR isolates in abscence of biocides. The fold changes in CF-BF/CF-PK of the HR isolates in the presence of biocides varied with the type of biocides, whereas in non-HR isolates, biocides have no significant effect, or produce only a slight increase in the fold change of CF-BF/CF-PK.

Comparing mortality in patients with carbapenemase-producing carbapenem resistant Enterobacterales and non-carbapenemase-producing carbapenem resistant Enterobacterales bacteremia

Carbapenem-resistant Enterobacterales (CRE) are classified as either carbapenemase-producing CRE (CP-CRE) or non-carbapenemase-producing CRE (non-CP-CRE) based on their mechanism of carbapenem resistance. Few studies have compared outcomes associated with each type of infection. We attempted to determine if either CRE subset is associated with increased mortality. We performed a retrospective observational study to collect demographic, clinical and outcomes data to compare patients with CP-CRE and non-CP-CRE bacteremia. Of 146 cases analyzed, 88/146 (60%) were CP-CRE and 58/146 (40%) were non-CP-CRE. Patients with CP-CRE bacteremia were less likely to receive active empiric or targeted antibiotic therapy. Non-CP-CRE bacteremia was associated with a 2.4 times higher hazard of death at 30 days after bacteremia onset compared to CP-CRE (HR, 2.4; 95% CI, 1.2, 4.6). Patients with non-CP-CRE bacteremia had a higher hazard of death at 30 days after bacteremia onset compared to those with CP-CRE bacteremia.

Incidence of a subsequent carbapenem-resistant Enterobacteriaceae infection after previous colonisation or infection: a prospective cohort study

OBJECTIVES

In patients with a history of carbapenemase-producing, carbapenem-resistant Enterobacteriaceae (CP-CRE), the need for CP-CRE targeted treatment in subsequent sepsis episodes is unclear. This study aimed to characterise the incidence of subsequent CP-CRE infective episodes in individuals with prior CP-CRE colonisation and/or infection, and identify predictors for these subsequent CP-CRE infections.

METHODS

All adult inpatients with CP-CRE detected from any site between June 2012 and May 2014 at a tertiary-care hospital were prospectively followed for two years to assess for any subsequent CP-CRE infections. Potential factors to which patients were exposed during the follow-up period were collected from medical records and analysed.

RESULTS

A total of 171 patients were enrolled. Of 151 patients who entered the follow-up period, 16 (10.6%) developed a subsequent CP-CRE infection. The median time to a subsequent infective episode was 24.5 days (12-105 days). The type of carbapenemase was highly conserved within index and subsequent paired episodes (16 of 17 pairs). Patients with first CP-CRE isolated from intra-abdominal or respiratory sources were ≥7 times more likely to develop a subsequent infection, while most rectal carriers remain colonised. For carriers (n = 133), Klebsiella spp. (OR 4.7) and OXA carbapenemase (OR 9.4) were significant predictors of subsequent infection. In patients with initial infection (n = 18), end-stage renal failure requiring dialysis (OR 22.0) was the only predisposing factor.

CONCLUSION

The incidence of subsequent infections in patients with prior colonisation was low. Consideration for CP-CRE targeted therapy is recommended in patients on dialysis and previous CP-CRE infections involving the bloodstream and/or respiratory tract.

Effect on 30-day mortality and duration of hospitalization of empirical antibiotic therapy in CRGNB-infected pneumonia

BACKGROUND

The objective of this study was to investigate whether unreasonable empirical antibiotic treatment (UEAT) had an impact on 30-day mortality and duration of hospitalization in bacterial pneumonia caused by carbapenem-resistant gram-negative bacteria (CRGNB).

METHODS

This was a retrospective cohort study involving CRGNB-infected pneumonia. All CRGNB-infected pneumonia patients received empirical and targeted antibiotic treatment (TAT), and they were divided into reasonable empirical antibiotic treatment (REAT) and UEAT according to whether the empirical antibiotic treatment (EAT) was reasonable. The data of the two groups were compared to analyze their influence on the 30-day mortality and hospitalization time in CRGNB-infected pneumonia patients. Moreover, we also considered other variables that might be relevant and conducted multivariable regression analysis of 30-day mortality and duration of hospitalization in CRGNB-infected pneumonia patients.

RESULTS

The study collected 310 CRGNB-infected pneumonia patients, the most common bacterium is Acinetobacter baumannii (211/310 [68%]), the rest were Klebsiella pneumoniae (46/310 [15%]), Pseudomonas aeruginosa and others (53/310 [17%]). Among them, 76/310 (24.5%) patients received REAT. In the analysis of risk factors, dementia, consciousness were risk factors of 30-day mortality, pulmonary disease, hemodynamic support at culture taken day and recent surgery were risk factors for longer hospital stay. The analysis of 30-day mortality showed that UEAT was not associated with 30-day mortality for the 30-day mortality of REAT and UEAT were 9 of 76 (11.84%) and 36 of 234 (15.38%) (P = 0.447), respectively. Meanwhile, there was difference between REAT and UEAT (P = 0.023) in the analysis of EAT on hospitalization time in CRGNB-infected pneumonia patients.

CONCLUSIONS

UEAT was not associated with 30-day mortality while was related to duration of hospitalization in CRGNB-infected pneumonia patients, in which Acinetobacter baumanniii accouned for the majority.

Infections caused by carbapenemase-producing Enterobacteriaceae: risk factors, clinical features and prognosis

Infections caused by carbapenem-producing Enterobacteriaceae (CPE) can present as several infectious syndromes, but they primarily present as respiratory, urinary and blood stream infections (primary or catheter-related) that are usually found as nosocomial or healthcare-associated infections. The risk of CPE infection is influenced by individual factors, such as the length of the hospital stay and their exposure to invasive procedures and/or to antimicrobials. Of note, exposure to several antimicrobials, not only carbapenems, has been linked to CPE colonization; the duration of antibiotic exposure is one of the primary drivers of CPE acquisition. Individual risk factors must be considered jointly with the local epidemiology of these microorganisms in healthcare institutions. Overall, these infections have a high associated mortality. Mortality is influenced by host factors (e.g., age, comorbidity and immune deficiency), infection-related variables (e.g., type and severity of the infection) and treatment-related factors such as the delay in the initiation of appropriate antimicrobial therapy and the use or monotherapy or combined antimicrobial therapy. Gaining knowledge concerning the epidemiology, clinical features and prognostic features of CPE infection could be useful for improving infection prevention and for the management of patients with infections caused by these microorganisms.

Efficacy of polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infections: a systematic review and meta-analysis

In recent years, carbapenem-resistant Enterobacteriaceae has become endemic in many countries. Because of limited treatment options, the abandoned "old antibiotics", polymyxins, have been reintroduced to the clinic. To evaluate the clinical efficacy of polymyxins in the treatment of infections caused by carbapenem-resistant Enterobacteriaceae, we systemically searched the PubMed, Embase, and Cochrane Library databases and analyzed the available evidence. The Preferred Reporting Items for Systematic reviews and Meta-Analysis statement were followed, and the I(2) method was used for heterogeneity. Nineteen controlled and six single-arm cohort studies comprising 1086 patients met the inclusion criteria. For controlled studies, no significant difference was noted for overall mortality (OR, 0.79; 95% CI, 0.58-1.08; p=0.15), clinical response rate (OR, 1.24; 95% CI, 0.61-2.54; p=0.55), or microbiological response rate (OR, 0.59; 95% CI, 0.26-1.36; p=0.22) between polymyxin-treated groups and the control groups. Subgroup analyses showed that 28-day or 30-day mortality was lower in patients who received polymyxin combination therapy than in those who received monotherapy (OR, 0.36; 95% CI, 0.19-0.68; p<0.01) and the control groups (OR, 0.49; 95% CI, 0.31-0.75; p<0.01). The results of the six single-arm studies were in accordance with the findings of controlled studies. One controlled and two single-arm studies that evaluated the occurrence of nephrotoxicity reported a pooled incidence rate of 19.2%. Our results suggest that polymyxins may be as efficacious as other antimicrobial therapies for the treatment of carbapenem-resistant Enterobacteriaceae infection. Compared to polymyxin monotherapy, combination regimens may achieve lower 28-day or 30-day mortality. Future large-volume, well-designed randomized control trials are required to determine the role of polymyxins in treating carbapenem-resistant Enterobacteriaceae infections.