External quality assessments for microbiologic diagnosis of diphtheria in Europe.

The European Diphtheria Surveillance Network (EDSN) ensures the reliable epidemiological and microbiologic assessment of disease prevalence in the European Union. Here, we describe a survey of current diagnostic techniques for diphtheria surveillance conducted across the European Union and report the results from three external quality assessment (EQA) schemes performed between 2010 and 2014.

Diphtheria in the postepidemic period, Europe, 2000-2009.

Diphtheria incidence has decreased in Europe since its resurgence in the 1990s, but circulation continues in some countries in eastern Europe, and sporadic cases have been reported elsewhere. Surveillance data from Diphtheria Surveillance Network countries and the World Health Organization European Region for 2000-2009 were analyzed. Latvia reported the highest annual incidence in Europe each year, but the Russian Federation and Ukraine accounted for 83% of all cases. Over the past 10 years, diphtheria incidence has decreased by >95% across the region. Although most deaths occurred in disease-endemic countries, case-fatality rates were highest in countries to which diphtheria is not endemic, where unfamiliarity can lead to delays in diagnosis and treatment. In western Europe, toxigenic Corynebacterium ulcerans has increasingly been identified as the etiologic agent. Reduction in diphtheria incidence over the past 10 years is encouraging, but maintaining high vaccination coverage is essential to prevent indigenous C. ulcerans and reemergence of C. diphtheriae.

External quality assessment for the determination of diphtheria antitoxin in human serum.

Accurate determination of diphtheria toxin antibodies is of value in determining the rates of immunity within broad populations or the immune status of individuals who may be at risk of infection, by assessing responses to vaccination and immunization schedule efficacy. Here we report the results of an external quality assessment (EQA) study for diphtheria serology, performed within the dedicated surveillance network DIPNET. Twelve national laboratories from 11 European countries participated by testing a standard panel of 150 sera using their current routine method: Vero cell neutralization test (NT), double-antigen enzyme-linked immunosorbent assay (ELISA; DAE), dual double-antigen time-resolved fluorescence immunoassay (dDA-DELFIA), passive hemagglutination assay (PHA), toxin binding inhibition assay (ToBI), and in-house or commercial ELISAs. The objective of the study was not to identify the best assay, as the advantages and drawbacks of methods used were known, but to verify if laboratories using their routine method would have categorized (as negative, equivocal, or positive) a serum sample in the same way. The performance of each laboratory was determined by comparing its results on a quantitative and qualitative basis to NT results from a single reference laboratory, as this test is considered the in vitro "gold standard." The performance of laboratories using NT was generally very good, while the laboratories' performance using other in vitro methods was variable. Laboratories using ELISA and PHA performed less well than those using DAE, dDA-DELFIA, or ToBI. EQA is important for both laboratories that use in vitro nonstandardized methods and those that use commercial ELISA kits.

Predictors of death after severe Streptococcus pyogenes infection.

An evaluation of the relative importance of host and pathogen factors on the survival rate of patients with invasive Streptococcus pyogenes infection found a number of clinical and demographic factors to be associated with risk for death. Some evidence suggested a seasonal pattern to patient survival rate.

Changes in genetic diversity of the Bordetella pertussis population in the United Kingdom between 1920 and 2006 reflect vaccination coverage and emergence of a single dominant clonal type.

Pertussis (whooping cough) is a potentially fatal respiratory disease caused by the bacterium Bordetella pertussis. Despite effective vaccination programs, there has been concern in some developed countries that pertussis cases are on the increase. We characterized 703 clinical B. pertussis isolates collected in the United Kingdom between 1920 and 2006 using multilocus variable-number tandem repeat analysis (MLVA), pertactin (prnA) and pertussis toxin (ptxA) genotyping, and serotyping. The results showed that the genetic diversity of the bacterial population decreased during periods of high vaccine coverage. However, it was elevated between 1977 and 1986, when vaccine coverage in the United Kingdom was low and epidemics occurred. A high proportion of MLVA types during this epidemic period were novel, and the prnA(2) and prnA(3) alleles were seen for the first time in the United Kingdom. MLVA-27 appeared in 1982, was codominant during the 1998-to-2001 period, and comprised approximately 70% of isolates during both the 2002-to-2004 and the 2005-to-2006 periods. The United Kingdom is dominated currently by an MLVA-27 prnA(2) ptxA(1) serotype Fim3 clonal type. Even during recent periods dominated by MLVA-27, many novel types were found at low frequencies, suggesting that either there are a large number of uncommon MLVA types circulating at low frequencies or new types are constantly arising. This supports a hypothesis that MLVA-27 is under some form of positive selection conferring increased survival in a highly vaccinated population. There has been no significant change to the bacterial population in the first 2 years since the United Kingdom switched from a whole-cell to an acellular vaccine.

Clinical and microbiological characteristics of severe Streptococcus pyogenes disease in Europe.

In an attempt to compare the epidemiology of severe Streptococcus pyogenes infection within Europe, prospective data were collected through the Strep-EURO program. Surveillance for severe cases of S. pyogenes infection diagnosed during 2003 and 2004 was undertaken in 11 countries across Europe by using a standardized case definition and questionnaire. Patient data as well as bacterial isolates were collected and characterized by T and M/emm typing, and selected strains were analyzed for the presence of superantigen genes. Data were analyzed to compare the clinical and microbiological patterns of the infections across the participating countries. A total of 4,353 isolates were collected from 5,521 cases with severe S. pyogenes infections who were identified. A wide diversity of M/emm types (n = 104) was found among the S. pyogenes clinical isolates, but the M/emm type distribution varied broadly between participating countries. The 10 most predominant M/emm types were M/emm type 1 (M/emm1), M/emm28, M/emm3, M/emm89, M/emm87, M/emm12, M/emm4, M/emm83, M/emm81, and M/emm5, in descending order. A correlation was found between some specific disease manifestations, the age of the patients, and the emm types. Although streptococcal toxic shock syndrome and necrotizing fasciitis were caused by a large number of types, they were particularly associated with M/emm1 and M/emm3. The emm types included in the 26-valent vaccine under development were generally well represented in the present material; 16 of the vaccine types accounted for 69% of isolates. The Strep-EURO collaborative program has contributed to enhancement of the knowledge of the spread of invasive disease caused by S. pyogenes within Europe and encourages future surveillance by the notification of cases and the characterization of strains, which are important for vaccination strategies and other health care issues.

Severe Streptococcus pyogenes infections, United Kingdom, 2003-2004.

As part of a Europe-wide initiative to explore current epidemiologic patterns of severe disease caused by Streptococcus pyogenes, the United Kingdom undertook enhanced population-based surveillance during 2003-2004. A total of 3,775 confirmed cases of severe S. pyogenes infection were identified over 2 years, 3.33/100,000 population, substantially more than previously estimated. Skin/soft tissue infections were the most common manifestation (42%), followed by respiratory tract infections (17%). Injection drug use was identified as a risk factor for 20% of case-patients. One in 5 infected case-patients died within 7 days of diagnosis; the highest mortality rate was for cases of necrotizing fasciitis (34%). Nonsteroidal antiinflammatory drugs, alcoholism, young age, and infection with emm/M3 types were independently associated with increased risk for streptococcal toxic shock syndrome. Understanding the pattern of these diseases and predictors of poor patient outcome will help with identification and assessment of the potential effect of targeted interventions.

International quality assurance study for characterization of Streptococcus pyogenes.

Surveillance of group A streptococcal (GAS) infections was undertaken as a major component of the European Commission-funded project on severe GAS disease in Europe (strep-EURO). One aim of strep-EURO was to improve the quality of GAS characterization by standardization of methods. An external quality assurance study (EQA) was therefore carried out to evaluate current global performance. Eleven strep-EURO and seven other streptococcal reference centers received a panel of 20 coded GAS isolates for typing. Conventional phenotypic typing (based on cell surface T and M protein antigens and opacity factor [OF] production) and molecular methods (emm gene typing) were used either as single or combined approaches to GAS typing. T typing was performed by 16 centers; 12 centers found one or more of the 20 strains nontypeable (typeability, 89%), and 11 centers reported at least one incorrect result (concordance, 93%). The 10 centers that tested for OF production achieved 96% concordance. Limited availability of antisera resulted in poor typeability values from the four centers that performed phenotypic M typing (41%), three of which also performed anti-OF typing (typeability, 63%); however, concordance was high for both M (100%) and anti-OF (94%) typing. In contrast, the 15 centers that performed emm gene sequencing achieved excellent typeability (97%) and concordance (98%), although comparison of the performance between centers yielded typeability rates from 65 to 100% and concordance values from 83 to 100%. With the rapid expansion and use of molecular genotypic methods to characterize GAS, continuation of EQA is essential in order to achieve international standardization and comparison of type distributions.

Clinical risk management in obstetrics: eclampsia drills.

PROBLEM: Infrequent presentation of patients with eclampsia, leading to staff inexperienced in the condition and untested emergency systems. DESIGN: "Fire drill" programme using on-site simulation of patients with eclampsia. SETTING: Tertiary referral obstetric unit. KEY MEASURES FOR IMPROVEMENT: Successful implementation of measures to optimise management of eclampsia. STRATEGIES FOR CHANGE: Rapid activation of emergency team after one call, development and dissemination of evidence based protocol for eclampsia, strategically placed "eclampsia boxes," individual staff feedback and education. EFFECTS OF CHANGE: Efficient and appropriate management of subsequent simulated patients. LESSONS LEARNT: On-site simulation can identify and correct potential deficiencies in the care of patients with eclampsia.