Emergence of VIM-4- and SHV-12-producing Enterobacter cloacae in a neonatal intensive care unit

Hospitalization costs for patients colonized with carbapenemase-producing Enterobacterales during an Australian outbreak

BACKGROUND

Carbapenem-producing Enterobacterales are an expanding group of Gram-negative bacteria that are resistant to carbapenems and cause over 9000 cases of hospital-associated infections in the USA. Efforts to quantify the economic and societal burden to healthcare are important to inform resource planning to implement infection control programmes.

AIM

We estimated the healthcare costs during an outbreak of carbapenemase-producing Escherichia coli OXA-181 in Australia. We aimed to understand the economic burden to hospitals of patients who are asymptomatically colonized with high-risk bacteria.

METHODS

Hospital admissions data and associated costs were obtained from the State Health Department. Colonized patients were matched to non-colonized patients on age, sex, admission ward and diagnostic category. Mean healthcare costs and length of stay were examined using generalized linear models and accounted for time-dependent bias, patient age and ward location.

FINDINGS

On average, colonized patients had six times higher mean costs (AU$155,784; 95% confidence interval (CI): AU$77,892-285,604) than non-colonized patients (AU$25,964). Mean costs for those aged 75-79 years were 50% lower (P=0.02) compared with the youngest subgroup, 35-39 years of age. The mean extended length of stay was 12 days (95% CI: 3-21) for colonized patients. Nursing care was the main driver of overall costs for colonized (44%) and non-colonized (39%) patients.

CONCLUSION

Patients colonized with carbapenem-producing Enterobacterales during an official hospital outbreak incurred higher costs than non-colonized patients. Although infected patients incur substantial economic burden to hospitals, the costs incurred by colonized patients is also high.

VIM/IMP carbapenemase-producing Enterobacteriaceae in Poland: epidemic Enterobacter hormaechei and Klebsiella oxytoca lineages

Objectives

To analyse VIM/IMP-type MBL-producing Enterobacteriaceae isolates identified in Poland during 2006-12.

Methods

Isolates were typed by PFGE, followed by MLST. blaVIM/IMP genes were amplified and sequenced within class 1 integrons. Their plasmidic versus chromosomal location was assessed by nuclease S1 and I-CeuI plus hybridization experiments. Plasmids were characterized by transfer assays and PCR-based replicon typing.

Results

One hundred and nineteen VIM/IMP-positive Enterobacteriaceae cases were reported in Poland from the first case in 2006 until 2012. The patients were in 54 hospitals and were infected or colonized by 121 organisms, including Enterobacter cloacae complex (n = 64), Klebsiella oxytoca (n = 23), Serratia marcescens (n = 20) and Klebsiella pneumoniae (n = 11). The isolates represented numerous pulsotypes and mainly original STs, and carried eight integrons with blaVIM-1-like genes (blaVIM-1/-4/-28/-37/-40; n = 101), three with blaVIM-2 variants (blaVIM-2/-20; n = 17) and one with blaIMP-19 (n = 3). Six integrons were new, and five and two formed prevalent families of In238-like (n = 96) and In1008-like (n = 16) elements, respectively. In238 (aacA4-blaVIM-4rpt) and In1008 (blaVIM-2-aacA4) had been originally observed in Polish Pseudomonas aeruginosa, suggestive of their transfer to enterobacteria, followed by spread and diversification. Four organisms have disseminated inter-regionally, i.e. Enterobacter hormaechei ST90 with plasmidic In238/In238a integrons (n = 36), K. oxytoca ST145 with a chromosomal In237-like element (n = 18) and two subclones of E. hormaechei ST89 with In1008- or In238-type variants (n = 8 and n = 7, respectively).

Conclusions

The epidemiology of VIM/IMP-producing Enterobacteriaceae in Poland has revealed a remarkable number of specific or novel characteristics of the organisms, with some possible links to other mid-southern European countries.

The β-Lactamase Gene Profile and a Plasmid-Carrying Multiple Heavy Metal Resistance Genes of Enterobacter cloacae

In this work, by high-throughput sequencing, antibiotic resistance genes, including class A (bla_CTX-M, bla_Z, bla_TEM, bla_VEB, bla_KLUC, and bla_SFO), class C (bla_SHV, bla_DHA, bla_MIR, bla_AZECL-29, and bla_ACT), and class D (bla_OXA) β-lactamase genes, were identified among the pooled genomic DNA from 212 clinical Enterobacter cloacae isolates. Six bla_MIR-positive E. cloacae strains were identified, and pulsed-field gel electrophoresis (PFGE) showed that these strains were not clonally related. The complete genome of the bla_MIR-positive strain (Y546) consisted of both a chromosome (4.78 Mb) and a large plasmid pY546 (208.74 kb). The extended-spectrum β-lactamases (ESBLs) (bla_SHV-12 and bla_CTX-M-9a) and AmpC (bla_MIR) were encoded on the chromosome, and the pY546 plasmid contained several clusters of genes conferring resistance to metals, such as copper (pco), arsenic (ars), tellurite (ter), and tetrathionate (ttr), and genes encoding many divalent cation transporter proteins. The comparative genomic analyses of the whole plasmid sequence and of the heavy metal resistance gene-encoding regions revealed that the plasmid sequences of Klebsiella pneumoniae (such as pKPN-332, pKPN-3967, and pKPN-262) shared the highest similarity with those of pY546. It may be concluded that a variety of β-lactamase genes present in E. cloacae which confer resistance to β-lactam antibiotics and the emergence of plasmids carrying heavy metal resistance genes in clinical isolates are alarming and need further surveillance.

Outbreak of nosocomial NDM-1-producing Klebsiella pneumoniae ST1419 in a neonatal unit

OBJECTIVES

The aim of this study was to characterise carbapenem-resistant Klebsiella pneumoniae isolates recovered from neonatal clinical specimens over a 4-month period.

METHODS

Seven carbapenem-resistant K. pneumoniae isolates were analysed. Antibiotic susceptibilities of the isolates were determined by the agar dilution method, and the drug resistance genes were evaluated by PCR. Clonal relatedness of the isolates was assessed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Conjugation experiments and Southern blot hybridisation were performed to determine the transferability of the plasmids.

RESULTS

All of the K. pneumoniae isolates carried the bla_NDM-1 gene but were negative for all other carbapenemases tested. All of the isolates harboured bla_SHV-12, and five isolates also carried bla_CTX-M-15 and/or bla_TEM-1. All of the isolates exhibited multidrug resistance. The isolates belonged to sequence types ST1419 and ST101 and formed three different PFGE patterns. Plasmids carrying bla_NDM-1 were successfully transferred from six of the seven isolates to the Escherichia coli recipient. These six NDM-1-producing K. pneumoniae were clonal and carried bla_NDM-1 on the same plasmid, but one isolate possibly carried chromosomal bla_NDM-1.

CONCLUSIONS

This is the first report of NDM-1-positive K. pneumoniae ST1419 from neonates in China. Closer attention should be paid to monitoring bla_NDM-1 gene dissemination because it is potentially transferred horizontally.

Notes from the Field: Verona Integron-Encoded Metallo-Beta-Lactamase-Producing Carbapenem-Resistant Enterobacteriaceae in a Neonatal and Adult Intensive Care Unit--Kentucky, 2015

During August 4-September 1, 2015, eight cases of Verona integron-encoded metallo-beta-lactamase (VIM)-producing Carbapenem-resistant Enterobacteriaceae (CRE) colonization were identified in six patients, using weekly active surveillance perirectal cultures in a Kentucky tertiary care hospital. No cases of clinical infection or complications attributable to colonization were reported. Four of the eight isolates were identified as Enterobacter cloacae; other organisms included Raoultella species (one), Escherichia coli (one), and Klebsiella pneumoniae (two). Six isolates were reported in a neonatal intensive care unit (ICU), and two isolates in an adult trauma and surgical ICU. Patient ages at isolate culture date ranged from 21 days to 68 years. Fifty percent of the patients were male. Previously, only one VIM-producing CRE-colonized patient (an adult, in 2013) had been reported by the same hospital. The six cases are the largest occurrence of VIM-producing CRE colonization reported in the United States and the only recognized cluster of VIM-producing CRE colonization in the United States reported to include a neonatal population. Despite environmental sampling over the same period, surveying patients for exposure to health care outside the United States, surveying health care providers for risk factors, and surveillance culturing of health care provider nares and axillae, a source of VIM-producing CRE has not been identified for this cluster. Prevention measures throughout the ICUs have been enhanced in response to this cluster, as detailed in CDC's 2015 CRE toolkit update.

Association of antibiotic resistance with SHV-12 extended-spectrum β-lactamase in Enterobacter cloacae

The association between antibiotic resistance and SHV-12 extended-spectrum β-lactamase (ESBL) in Enterobacter cloacae remains unknown. The aim of the present study was to investigate the prevalence of both chromosome- and plasmid-borne SHV-12 ESBL genes in Enterobacter cloacae. Transmission of the SHV-12 ESBL gene was explored, and the risk factors for antibiotic resistance in E. cloacae were analyzed. Polymerase chain reaction (PCR) results showed that 58 out of the 100 isolates carried the SHV-12 ESBL gene: 34.48% of them occurred in the chromosome, 48.28% were plasmid-borne and 17.24% appeared in both. Enterobacterial repetitive intergenic consensus-PCR tests detected 82 chromosomal genotypes. Conjugation assays showed that 70.00% of plasmid-borne SHV-12 ESBL genes were successfully transconjugated into E. coli C600 and that the antibiotic resistance phenotype of E. cloacae was partially (84%) or completely (10%) transferred. A significantly higher SHV-12 ESBL detection rate was found in patients with underlying conditions and/or complications compared with those without (P<0.05). The detection of SHV-12 ESBL-producing E. cloacae from vertical transmission varied significantly across clinical departments and age groups (P<0.05), with the highest rates in the intensive care unit and the group of patients aged ≥60 years. The present results indicate that the location and transmission efficiency of SHV-12 ESBL are closely correlated with the antibiotic resistance of E. cloacae.

Infection and colonization by Stenotrophomonas maltophilia: antimicrobial susceptibility and clinical background of strains isolated at a tertiary care centre in Hungary

BACKGROUND

Stenotrophomonas maltophilia is an important opportunistic, mainly nosocomial pathogen that emerged in the last decades worldwide. Due to its inherent extended antibiotic resistance, therapeutic options are strongly limited. New resistance mechanisms in S. maltophilia make antibiotic therapy even more difficult. The aim of our study was to investigate the antimicrobial resistance of S. maltophilia isolates collected in our laboratory and to reveal related clinical background.

METHOD

Consecutive non-duplicate S. maltophilia isolates (n = 160) were collected in a three-year period. Conventional methods, automated identification system and MALDI-TOF MS was used for identification, ERIC-PCR for genetic relationship analysis and broth microdilution method to determine the susceptibility for trimethoprim/sulfamethoxazole (SXT), ciprofloxacin, levofloxacin, moxifloxacin, colistin, doxycycline and tigecycline. Clinical final reports were used retrospectively to collect clinical information.

RESULTS

ERIC-PCR revealed large heterogeneity. Trimethoprim/sulfamethoxazole, moxifloxacin and levofloxacin were found to be the most effective agents with MIC50/MIC90 0.5/1, 0.25/1, 1/2 mg/l, respectively. Seventy percent of patients with S. maltophilia infection were treated in intensive care units. All-cause mortality rate was 45%. Nearly 70% of the isolates were collected from polymicrobial infections/colonizations.

CONCLUSIONS

Trimethoprim/sulfamethoxazole is the most potent antibiotic agent against S. maltophilia. In case of SXT hypersensitivity, intolerance or resistance, fluoroquinolones are alternative therapeutic options. Missing clinical breakpoints, consensus antibiotic susceptibility testing guidelines and clinical trials make the interpretation of antibiotic susceptibility testing results difficult. The indirect pathogenicity of S. maltophilia in polymicrobial infections or colonizations has to be taken into consideration.

Monoclonal outbreak of VIM-1-carbapenemase-producing Enterobacter cloacae in intensive care unit, University Hospital Centre Split, Croatia

Emergence of carbapenem-resistant Enterobacteriaceae has become a substantial global health problem. The aim of this study was to analyze carbapenem-resistant isolates of Enterobacter cloacae that have emerged for the first time in the intensive care unit (ICU) at the University Hospital Centre Split, Croatia. The strains were selected in the period between June and August 2012, according to their susceptibility patterns to carbapenems. Resistant isolates were screened for metallo-β-lactamase (MBL) production with the use of the imipenem-EDTA disk synergy test, and positive findings were confirmed by PCR. The type of VIM β-lactamase gene was determined by sequencing of PCR products. The genetic relatedness was evaluated using pulsed-field gel electrophoresis analysis. The demographic and clinical data were retrospectively analyzed from medical records. Five patients were infected and one patient was colonized with a single clone of multidrug-resistant VIM-1-producing E. cloacae susceptible only to colistin. Three cases of lower respiratory tract infections, one case of bacteremia, and one case of intra-abdominal infection were identified. All cases were hospital-acquired after prolonged stay in ICU. All patients had serious underlying diseases and received a broad-spectrum antibiotic. Four patients died and two had unimprovable medical condition at the time of discharge from the hospital. MBL-producing E. cloacae can cause fatal infection in severely ill patients. Monoclonal outbreak highlights the need for continuous surveillance and good infection control practices to prevent further spread since the antibiotic therapy options for infections caused by such strains are strongly limited.