Incidence and Risk Factors for Acquisition of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Newborns in Seville, Spain: A Prospective Cohort Study

BACKGROUND

ESBL-producing Enterobacteriaceae (ESBL-E) are an emerging cause of infections in children. Data are scarce on incidence rates and risk factors for acquisition of colonisation with ESBL-E.

METHODS

A total of 46 and 50 newborns from colonised and non-colonised mothers, respectively, were followed during one year after birth. Rectal swabs were performed every 3 months to detect ESBL-E; bla_ESBL were characterised and isolates were typed for comparison. Multivariate analysis for risk factors was performed using Cox regression.

RESULTS

Incidence density of any new acquisition and of first acquisition of ESBL-E was 2.7 and 1.9 episodes per 100 children-month, respectively, among children whose mothers were colonised, and 1.2 and 1.3, respectively, among children whose mothers were not. The weighted average prevalence of colonisation rates during the first year were 15.9% and 8%, respectively. No infections due to ESBL-E were detected. Living with pets at home, breastfeeding, sterilisation of feeding bottles and out-of-home childcare were protective for ESBL-E acquisition; having a colonised mother increased the risk. The most frequent ESBL types were CTX-M-14 and CTX-M-1. In 5/19 (26.3%) children with acquisition of new clones, the acquired ESBL-E was shared with their mothers.

CONCLUSIONS

Acquisition of ESBL-E colonisation is not rare during the first year of life. Breastfeeding and out-of-home childcare were protective for acquisition, and colonised mothers were associated with increased risk. However, the same clone was shared by mother and child in only a subset of acquisition episodes.

First report of NDM-1-producing clinical isolate of Leclercia adecarboxylata in Spain

We describe the case of NDM-1-producing Leclercia adecarboxylata recovered from the clinical sample of a patient hospitalized for a trauma-related injury to his foot. The isolate was resistant to all beta-lactams, quinolones, trimetroprim-sulfametoxazol, gentamicin and tobramicyn. The bla_NDM-1 gene was located in a conjugative plasmid that also contained the bla_SHV-12 gene and was preceded by a disrupted insertion sequence of ISAba125. The plasmid belongs to the incompatibility group X3, which is known to be an important vector for NDM-1 dissemination in China. This is the first reported case of NDM-1L. adecarboxylata in our country and evidences that species of uncertain clinical relevance can act as hidden sources of clinically important resistance determinants.

Epidemiology of infections caused by carbapenemase-producing Enterobacteriaceae: reservoirs and transmission mechanisms

The dissemination of carbapenemase-producing Enterobacteriaceae has occurred very quickly and has crossed borders rapidly between countries and continents. In some areas, it has exceeded the holding capacity of health systems, reaching epidemic proportions. This form of dissemination has not been the same for all enzymes, with KPC, NDM and OXA-48 genes having a greater ability to spread. These enzymes have primarily been spread clonally in the case of KPC-producing Klebsiella pneumoniae from the initial epicenter located in New York, with a very small number of strains causing outbreaks. For NDM and OXA- 48, these resistance determinants have been vehiculized by clones with a high transmission capacity; however, simultaneous horizontal transmission is also playing an important role. The most important identified reservoirs are colonized or infected individuals from endemic areas or centers with outbreaks, but the contaminated goods from these endemic areas also play a part. An international effort is needed to control the spread of these multiresistant pathogens.

Reduced Susceptibility to Cefepime in Clinical Isolates of Enterobacteriaceae Producing OXA-1 Beta-Lactamase

An increase of Enterobacteriaceae isolates with reduced susceptibility to cefepime (FEP) and amoxicillin/clavulanate (AMC) has been observed in our area. The aim of this study was to characterize this antibiotic resistance phenotype and its molecular epidemiology. A total of 33 Enterobacteriaceae strains were studied. blaOXA-1 genes and their genetic environment were analyzed by polymerase chain reaction (PCR) and sequencing. Plasmids were transferred by conjugation and/or transformation and classified using PCR-based inc/rep typing and IncF subtyping. Escherichia coli isolates were typed by phylogroup, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Outer membrane proteins were studied by sodium dodecylsulfate-polyacrylamide gel electrophoresis and expression of blaOXA-1 genes by reverse transcription-PCR. FEP minimum inhibitory concentration yielded values of 1-16 mg/L. Twenty-nine (87.9%) isolates produced OXA-1, of which 24 (82.7%) were located in class 1 integron, and 9 (27.3%) produced TEM-1. Among the 24 E. coli OXA-1-producers, PFGE revealed two main clusters: one belonged to C-ST88 and the other to B23-ST131. Thirteen plasmids containing blaOXA-1 were transferred, nine belonged to IncF replicon (4 F2:A1:B-, 2 F1:A1:B1, 1 F1:A2:B-, 1 F18:A2:B1, 1 F5:A-:B1) and four were nontypeable. In conclusion, reduced susceptibility to FEP was mostly due to OXA-1 beta-lactamase. In E. coli, this increase is mainly due to the dissemination of two clones, which have captured different IncF plasmids. Among non-E. coli strains, five isolates produced OXA-1 and one isolate produced only TEM-1.

Performance of EUCAST and CLSI approaches for co-amoxiclav susceptibility testing conditions for clinical categorization of a collection of Escherichia coli isolates with characterized resistance phenotypes

OBJECTIVES

There are different methodological recommendations for in vitro testing of the co-amoxiclav combination. Performance of co-amoxiclav MIC testing for Escherichia coli by the standard ISO microdilution method (ISO 20776-1) was compared using EUCAST (fixed 2 mg/L clavulanate concentration) and CLSI (2 : 1 ratio) interpretive criteria.

METHODS

MICs were determined by broth microdilution using a 2 : 1 ratio and fixed clavulanate concentrations (2 and 4 mg/L) for 160 clinical E. coli isolates with characterized resistance mechanisms. Essential agreements, categorical agreements and relative errors were determined.

RESULTS

For all isolates, essential agreement between microdilution using 2 mg/L clavulanate and a 2 : 1 ratio was 25.6%. For ESBL-producing isolates, considering EUCAST breakpoints, 55% of isolates tested with 2 mg/L clavulanate were classified as resistant; conversely, 95% of isolates tested with 4 mg/L clavulanate were susceptible. When using CLSI breakpoints and a 2 : 1 ratio, 90% of isolates were susceptible and 10% were intermediate.

CONCLUSIONS

Variation in the clavulanate concentration gave different susceptibility testing results, particularly among ESBL-producing E. coli isolates. The in vitro concentration of clavulanate that better correlates with clinical outcome is still under debate and should be established.

The global threat of antimicrobial resistance: science for intervention

In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.

Uncoupling between core genome and virulome in extraintestinal pathogenic Escherichia coli

Extraintestinal pathogenic Escherichia coli (ExPEC) are among the most frequently isolated bacterial pathogens in hospitals. They are considered opportunistic pathogens and are found mostly in urinary and bloodstream infections. They are genetically diverse, and many studies have sought associations between genotypes or virulence genes and infection site, severity, or outcome, with varied, often contradictory, results. To understand these difficulties, we have analyzed the diversity patterns in the core genomes and virulomes of more than 500 ExPEC isolates from 5 different collections. The core genome was analyzed using a multilocus sequence type-based single-nucleotide polymorphism (SNP) pyrosequencing approach, while the virulence gene content (the virulome) was studied by polymerase chain reaction detection of 25 representative genes. SNP typing showed a similar population structure in the different collections: half of the isolates belong to a few sequence types (5 to 8), while the other half is composed of a large diversity of sequence types that are found once or twice. Sampling analysis by rarefaction plots of SNP profiles showed saturation curves indicative of a limited diversity. Contrary to this, the virulome shows an extremely high diversity, with almost as many gene profiles as isolates, and linear, nonsaturating, rarefaction plots, even within sequence types. These data show that genetic exchange rates are very heterogeneous along the chromosome, being much higher in the virulome fraction of the genome than in the core genome.

Long-Term Control of Endemic Hospital-Wide Methicillin-ResistantStaphylococcus aureus(MRSA): The Impact of Targeted Active Surveillance for MRSA in Patients and Healthcare Workers

Objective.

To evaluate the long-term impact of successive interventions on rates of methicillin-resistantStaphylococcus aureus(MRSA) colonization or infection and MRSA bacteremia in an endemic hospital-wide situation.

Design.

Quasi-experimental, interrupted time-series analysis. The impact of the interventions was analyzed by use of segmented regression. Representative MRSA isolates were typed by use of pulsed-field gel electrophoresis.

Setting.

A 950-bed teaching hospital in Seville, Spain.

Patients.

All patients admitted to the hospital during the period from 1995 through 2008.

Methods.

Three successive interventions were studied: (1) contact precautions, with no active surveillance for MRSA; (2) targeted active surveillance for MRSA in patients and healthcare workers in specific wards, prioritized according to clinical epidemiology data; and (3) targeted active surveillance for MRSA in patients admitted from other medical centers.

Results.

Neither the preintervention rate of MRSA colonization or infection (0.56 cases per 1,000 patient-days [95% confidence interval {CI}, 0.49-0.62 cases per 1,000 patient-days]) nor the slope for the rate of MRSA colonization or infection changed significantly after the first intervention. The rate decreased significantly to 0.28 cases per 1,000 patient-days (95% CI, 0.17-0.40 cases per 1,000 patient-days) after the second intervention and to 0.07 cases per 1,000 patient-days (95% CI, 0.06-0.08 cases per 1,000 patient-days) after the third intervention, and the rate remained at a similar level for 8 years. The MRSA bacteremia rate decreased by 80%, whereas the rate of bacteremia due to methicillin-susceptibleS. aureusdid not change. Eighty-three percent of the MRSA isolates identified were clonally related. All MRSA isolates obtained from healthcare workers were clonally related to those recovered from patients who were in their care.

Conclusion.

Our data indicate that long-term control of endemic MRSA is feasible in tertiary care centers. The use of targeted active surveillance for MRSA in patients and healthcare workers in specific wards (identified by means of analysis of clinical epidemiology data) and the use of decolonization were key to the success of the program.

Characterisation of the first ongoing outbreak due to KPC-3-producing Klebsiella pneumoniae (ST512) in Spain

The aim of this study was to characterise carbapenem-resistant Klebsiella pneumoniae isolates that caused an outbreak in a hospital in the south of Spain, originating from a patient transferred in 2012 from Italy. Forty-four K. pneumoniae isolates, recovered from 28 patients, were screened by PCR for extended-spectrum β-lactamase (ESBL) and carbapenemase genes and the products were further sequenced. Plasmids were transferred by electroporation and were classified using PCR-based Inc/rep typing and IncF subtyping. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to determine the genetic relatedness of the isolates. All isolates yielded positive modified Hodge test results, harboured bla(SHV-11), bla(TEM-1) and bla(KPC-3) genes, showed an identical PFGE pattern, and were assigned to clone sequence type 512 (ST512). The bla(KPC-3) gene was located on a 140-kb K2:A-:B-plasmid. In conclusion, the successful K. pneumoniae ST512 clone caused a major outbreak in Spain from an imported case and is the first description of an outbreak in this country due to the KPC-3-producing K. pneumoniae ST512 clone.

Escherichia coli belonging to the worldwide emerging epidemic clonal group O25b/ST131: risk factors and clinical implications

OBJECTIVES

Escherichia coli belonging to clonal group ST131 has emerged as a significant contributor to infection caused by antibiotic-resistant E. coli worldwide. We investigated the risk factors for infections caused by ST131 E. coli and their clinical implications.

METHODS

One thousand and seventy-seven E. coli isolates were screened for ST131 by molecular methods. Risk factors for ST131 were investigated separately for patients with E. coli producing and not producing extended-spectrum β-lactamases (ESBLs) in the Seville area, Spain. Multivariate analysis using logistic regression was performed. Patients with infections caused by ST131 and non-ST131 isolates were prospectively followed.

RESULTS

Independent risk factors for non-ESBL-producing ST131 were female gender (OR: 1.94; 95% CI: 1.07-3.51), diabetes mellitus (OR: 2.17; 95% CI: 1.29-3.67), bedridden status (OR: 7.75; 95% CI: 0.70-85.07) and exposure to amoxicillin/clavulanate (OR: 2.07; 95% CI: 1.08-3.96) or fluoroquinolones (OR: 2.48; 95% CI: 1.41-4.34). For ESBL-producing ST131, male gender was an independent risk factor (OR: 2.20; 95% CI: 0.94-5.11), while healthcare-related acquisition and exposure to any previous antibiotic were protective (OR: 0.30; 95% CI: 0.13-0.71; and OR: 0.43; 95% CI: 0.19-1.00, respectively). Overall, the severity of sepsis, bacteraemia and mortality were similar among ST131 and non-ST131 groups. The presence of typical factors predisposing to E. coli infection was more frequent in non-ESBL-producing ST131 than in controls (76% versus 57.2%, P = 0.005).

CONCLUSIONS

Previous use of antibiotics selecting for ST131 isolates was the main modifiable risk factor for infections caused by these isolates. Our results also suggest that the clinical virulence of ST131 is not higher than that of other common E. coli causing infections.

Virulence profiles of bacteremic extended-spectrum β-lactamase-producing Escherichia coli: association with epidemiological and clinical features

There is scarce data about the importance of phylogroups and virulence factors (VF) in bloodstream infections (BSI) caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC). A prospective multicenter Spanish cohort including 191 cases of BSI due to ESBLEC was studied. Phylogroups and 25 VF genes were investigated by PCR. ESBLEC were classified into clusters according to their virulence profiles. The association of phylogropus, VF, and clusters with epidemiological features were studied using multivariate analysis. Overall, 57.6%, 26.7%, and 15.7% of isolates belonged to A/B1, D and B2 phylogroups, respectively. By multivariate analysis (adjusted OR [95% CI]), virulence cluster C2 was independently associated with urinary tract source (5.05 [0.96–25.48]); cluster C4 with sources other than urinary of biliary tract (2.89 [1.05–7.93]), and cluster C5 with BSI in non-predisposed patients (2.80 [0.99–7.93]). Isolates producing CTX-M-9 group ESBLs and from phylogroup D predominated among cluster C2 and C5, while CTX-M-1 group of ESBL and phylogroup B2 predominantes among C4 isolates. These results suggest that host factors and previous antimicrobial use were more important than phylogroup or specific VF in the occurrence of BSI due to ESBLEC. However, some associations between virulence clusters and some specific epidemiological features were found.

Increased raw poultry meat colonization by extended spectrum beta-lactamase-producing Escherichia coli in the south of Spain

The present study was conducted to assess the prevalence of retail chicken and turkey meat colonized by extended-spectrum beta-lactamase-producing Escherichia coli (ESBLEC) in Seville, Spain. ESBLEC recovered from meat samples purchased in 2010 were characterized by specific PCR analysis for bla genes, phylogenetic groups and subgroups (genotypes) and O25b/pabB/B2 traits of ST131. Results were compared with those obtained in a previous study in 2007, when a high percentage of retail meat samples were found to be colonized by ESBLEC. The prevalence of retail poultry meat colonized by ESBLEC increased from 62.5% in 2007 to 93.3% in 2010 (p=0.005). Non-pathogenic B1 and A(1) genotypes accounted for more than 60% of the 60 isolates recovered. Sequence type ST131 or B2 phylogroup isolates were not detected. Clonal relatedness was detected in just 2 CTX-M-1-producing isolates from 2 chicken samples belonging to phylogenetic group A, genotype A(1). There continued to be a significantly high quinolone resistance, with 85.4% and 32.2% of isolates showing resistance to nalidixic acid and ciprofloxacin, respectively. SHV-12 was the most common ESBL harbored by E. coli, although it has decreased in prevalence since 2007. Meanwhile, CTX-M ESBLs prevalence has increased. We conclude that the trend of colonization by ESBLECs-particularly CTX-M-producing isolates-in raw poultry meat has increased in a short period of time in our area.