Multi-centre evaluation of a phenotypic extended spectrum β-lactamase detection guideline in the routine setting

AbstractThis study aimed to evaluate the routine setting performance of a guideline for phenotypic detection of extended spectrum β-lactamases (ESBLs) in Enterobacteriaceae, recommending ESBL confirmation with Etest or combination disc for isolates with a positive ESBL screen test (i.e. cefotaxime and/or ceftazidime MIC >1 mg/L or an automated system ESBL warning). Twenty laboratories submitted 443 Enterobacteriaceae with a positive ESBL screen test and their confirmation test result (74% Escherichia coli, 12% Enterobacter cloacae, 8% Klebsiella pneumoniae, 3% Proteus mirabilis, 2% Klebsiella oxytoca). Presence of ESBL genes was used as reference test. Accuracy of local phenotypic ESBL detection was 88%. The positive predictive value (PPV) of local screen tests was 70%, and differed per method (Vitek-2: 69%, Phoenix: 68%, disc diffusion: 92%), and species (95% K. pneumoniae-27% K. oxytoca). A low PPV (3%) was observed for isolates with automated system alarm but third-generation cephalosporin MICs <2 mg/L. Local ESBL confirmation had a PPV and negative predictive value (NPV) of 93% and 90%, respectively. Compared with centrally performed confirmation tests, 7% of local tests were misinterpreted. Combination disc was more specific than Etest (91% versus 61%). Confirmation tests were not reliable for P. mirabilis and K. oxytoca (PPV 33% and 38%, respectively, although NPVs were 100%). In conclusion, performance of Etests could be enhanced by education of technicians to improve their interpretation, by genotypic ESBL confirmation of P. mirabilis and K. oxytoca isolates with positive phenotypic ESBL confirmation, and by interpreting isolates with a positive ESBL alarm but an MIC <2 mg/L for cefotaxime and ceftazidime as ESBL-negative

Detection and epidemiology of extended-spectrum beta-lactamases

The rising prevalence of extended-spectrum beta-lactamase (ESBL-)producing Enterobacteriaceae threatens public health, as treatment options in case of infections are reduced. Rapid detection of carriage or infection of ESBL-producing bacteria is crucial for appropriate infection control measures and decision making regarding (empirical) therapy in case of infections. This thesis aims to provide deeper insight in the possibilities to detect patients carrying ESBL-producing bacteria quickly and accurately. ESBL-detection in the Netherlands is reliable, as in 88% of cases the correct ESBL-status was assigned to isolates in daily practice, using the Dutch guideline for phenotypic detection of ESBLs in Enterobacteriaceae. The positive predictive value of the screentest was on average 70%, but was dependent on the method, the species and the minimum inhibitory concentration (MIC) for the third-generation cephalosporins. The ESBL-Etest was less specific as compared to the combination disk (59% versus 92%) for ESBL confirmation. Another tool to detect ESBL-producing Enterobacteriaceae is the Check-KPC ESBL microarray, which had a sensitivity of 97%, specificity of 98%, positive-predictive value of 99% and negative-predictive value of 92%. Resistance for third-generation cephalosporins in Enterobacteriaceae in the Netherlands results mainly from CTX-M-15 ESBL genes in E. coli, frequently belonging to sequence type (ST)131. CTX-M-15 isolates were –on average– susceptible to less antibiotics than isolates harboring TEM-52, CTX-M-1, or CTX-M-14. The high prevalence of CTX-M-15 is comparable to most other countries. The hypothesis that ESBL-producing Enterobacteriaceae circulate in two separate compartments, one in the community fuelled by food contamination and one in hospitals fuelled by cross-transmission, could not be confirmed. Resistance patterns differed between the poultry-associated and non-poultry associated isolates with higher susceptibility for aminoglycosides and fluoroquinolones in the CTX-M-1 and TEM-52 positive isolates from humans. At hospital-admission, the prevalence of ESBL carriage was 8.2%, and was comparable among patients admitted from long-term care-facilities and home settings. Documented ESBL-carriage within 1 year before admission, hospital admission in the previous 6 months and male gender were associated with ESBL-carriage. It was not possible to develop a clinically useful prediction rule for ESBL carriage at hospital admission. ESBL-carriers frequently remained colonized for longer than a year after hospital-discharge, often with the same strain. Carriage of ESBL-producing bacteria positive for CTX-M-15 was associated with a longer duration of ESBL-carriage. At identification of ESBL-carriage, 32% of household contacts were colonized with ESBL-producing bacteria, as this was still >20% after 18 months. As screening all patients at hospital-admission for ESBL-carriage is not feasible, it could be considered to extend the screening for previous identified ESBL-carriers from 12 to 18 months, and additionally, to screen household contacts of previously identified ESBL-carriers at hospital admission

Urineweginfecties op de huisartsenpost: diagnostiek en behandeling kunnen beter.

This is a commentary on the article of Van der Spek et al. on the workload, diagnostic work-up and treatment of urinary tract infections in adults during out-of-hours primary care. Despite a well-established Dutch guideline on urinary tract infections, correctly diagnosing and prescribing antibiotics for urinary tract infections is a challenge that needs major improvement, especially during out-of-hours GP care

Evaluation of a commercial microarray as a confirmation test for the presence of extended-spectrum beta-lactamases in isolates from the routine clinical setting.

Item does not contain fulltextSince the diagnostic characteristics of the Check-KPC ESBL microarray as a confirmation test on isolates obtained in a routine clinical setting have not been determined, we evaluated the microarray in a random selection of 346 clinical isolates with a positive ESBL screen test (MIC >1 mg/L for cefotaxime or ceftazidime or an ESBL alarm from the Phoenix or Vitek-2 expert system) collected from 31 clinical microbiology laboratories in the Netherlands in 2009. Using sequencing as the reference method the sensitivity of the microarray was 97% (237/245), the specificity 98% (97/99), the positive predictive value 99% (237/239) and the negative predictive value 92% (97/105).1 september 201

Identieke resistentiegenen en plasmiden in Escherichia coli van Nederlandse patiënten, pluimvee en kippenvlees

Doel Bepalen welke ‘extended’-spectrum-bètalactamase(ESBL)-genen en plasmiden aanwezig zijn in Escherichia coli in vleeskuikens en vers kippenvlees uit Nederland en tevens in een voor Nederland representatieve collectie van klinische E. coli isolaten van patiënten. Opzet Beschrijvend. Methoden ESBL-producerende E. coli-isolaten waren afkomstig van 98 kipfilets, een ESBL-surveillance studie bij vleeskuikens uit 2006 en 516 humane klinische isolaten uit 31 laboratoria verzameld gedurende een periode van 3 maanden in 2009. De distributie werd vastgesteld van ESBL-genen en plasmiden in E. coli aanwezig in vleeskuikens en vers kippenvlees en de gevonden ESBL-genen werden gedefinieerd als ‘kip-geassocieerd’. In een voor Nederland representatieve steekproef van klinische E. coli-isolaten werd het aandeel van kip-geassocieerde ESBL-genen en plasmiden gekwantificeerd. De isolaten werden geanalyseerd met een ESBL-specifieke microarray, een ESBL-gensequentiebepaling, en 2 plasmide-typeringsmethoden: zogenaamde PCR-gebaseerde replicon-typering en plasmide-multi-locussequentietypering. Resultaten 6 ESBL-genen werden aangemerkt als ‘kip-geassocieerd’: bla CTXM-1, bla CTXM-2, bla SHV-2, bla SHV-12, bla TEM-20, bla TEM-52. Van de humane ESBL-producerende isolaten bevatte 35% een kip-geassocieerd ESBL-gen, en 19% een kip-geassocieerd ESBL-gen gelegen op een IncI1-plasmide, dat genetisch niet te onderscheiden was van plasmides afkomstig van vleeskuikens. In humane isolaten met een kip-geassocieerde ESBL’s waren bla CTXM-1 en bla TEM-52 de meest prevalente ESBL-genen (86%), net als in de isolaten van vleeskuikens (78%) en kipfilets (75%). Van de 98 kipfilets bevatte 94% een ESBL producerende E. coli. Conclusie Deze bevindingen zijn suggestief voor overdracht van ESBL producerende E. coli van pluimvee naar de mens via de voedselketen