Mary Meehan

Increased incidence of invasive group A streptococcal disease in Ireland, 2012 to 2013

Invasive group A streptococcal (iGAS) infections have been notifiable in Ireland since 2004. Incidence rates (2004-2011) have ranged from 0.8 to 1.65 per 100,000. In 2012, the iGAS rate rose to 2.66 per 100,000 and was associated with a high proportion of emm1 isolates. A further increase in January to June 2013 has been associated with increased prevalence of emm3. Public health departments and clinicians have been alerted to this increase.

Development of a diagnostic real-time polymerase chain reaction assay for the detection of invasive Haemophilus influenzae in clinical samples

Since the introduction of the Haemophilus influenzae serotype b vaccine, invasive H. influenzae disease has become dominated by nontypeable (NT) strains. Several widely used molecular diagnostic methods have been shown to lack sensitivity or specificity in the detection of some of these strains. Novel real-time assays targeting the fucK, licA, and ompP2 genes were developed and evaluated. The fucK assay detected all strains of H. influenzae tested (n = 116) and had an analytical sensitivity of 10 genome copies/polymerase chain reaction (PCR). This assay detected both serotype b and NT H. influenzae in 12 previously positive specimens (culture and/or bexA PCR) and also detected H. influenzae in a further 5 of 883 culture-negative blood and cerebrospinal fluid (CSF) samples. The fucK assay has excellent potential as a diagnostic test for detection of typeable and nontypeable strains of invasive H. influenzae in clinical samples of blood and CSF.

Noninvasive Pneumococcal Clones Associated with Antimicrobial Nonsusceptibility Isolated from Children in the Era of Conjugate Vaccines

ABSTRACT Carriage and noninvasive pneumococcal isolates frequently have a higher prevalence of antimicrobial nonsusceptibility than invasive isolates. From 2009 to 2014, we determined the associated clones in 169 pediatric noninvasive nonsusceptible pneumococci from a total of 506 isolates collected after 7- and 13-valent conjugate vaccine introduction (PCV7/13) to the Irish childhood immunization schedule in 2008 and 2010, respectively. We compared our results to those from 25 noninvasive pediatric pneumococcal isolates collected in 2007, the year before introduction of conjugate vaccines. In 2007, England14-9 and Spain9V-3 accounted for 12% and 32% of nonsusceptible clones, respectively, but in 2009 to 2014, their prevalence fell to 0% and 2.4%. Furthermore, there was a significant decline in Spain6B-2 and its variants from 2009 to 2014 (P = 0.0024). Fluctuations occurred in clonal complex 320 associated with serotype 19A. The prevalence of Sweden15A-25 and its variants and ST558 (a single-locus variant of Utah35B-24) associated with nonvaccine serotypes (NVT) 15A and 35B increased from 0% and 8% in 2007 to 19% and 16% in 2013 to 2014, respectively. Pilus locus 1 (PI-1) is associated with the spread of some nonsusceptible pneumococcal clones. PI-1 was more frequently associated with PCV7/13 serotypes than NVT (P = 0.0020). Our data highlight the value of surveillance of noninvasive pneumococci following conjugate vaccine introduction. Importantly, emerging clones associated with NVT may limit the effectiveness of PCV7/13 in reducing the high rate of nonsusceptibility among pediatric noninvasive pneumococci, with implications for empirical treatment strategies.

Group B streptococcal PCR testing in comparison to culture for diagnosis of late onset bacteraemia and meningitis in infants aged 7–90 days: a multi-centre diagnostic accuracy study

The aim of this study was to compare an in-house real-time PCR assay, with bacterial culture as the reference, for the diagnosis of late onset group B Streptococcal (GBS) disease. This was a retrospective review. All children aged 7–90 days presenting to four paediatric centres that had a blood or CSF sample tested by GBS PCR were included. Of 7,686 blood and 2,495 cerebrospinal fluid (CSF) samples from patients of all ages received for PCR testing, 893 and 859 samples were eligible for the study, respectively. When compared to culture, the sensitivity of blood PCR was 65% (13/20) in comparison to the CSF PCR test which was 100% (5/5). Ten of 23 PCR-positive blood samples and 17 of 22 PCR-positive CSF samples were culture negative. The median threshold Ct values for culture-positive/PCR-positive CSF samples was lower than that of culture-negative/PCR-positive CSF samples (p = 0.08). Clinical details of 17 available cases that were culture negative/PCR positive were reviewed; seven were deemed to be definite cases, eight were probable and two were possible. The results showed that detection of GBS by PCR is useful for CSF samples from infants aged 7–90 days with suspected meningitis; however, analysis of blood samples by PCR is of limited value as a routine screening test for late onset GBS sepsis and should not replace bacterial culture.

Epidemiology of an upsurge of invasive group A streptococcal infections in Ireland, 2012-2015

OBJECTIVES Group A streptococcus (GAS) is responsible for mild to very severe disease. The epidemiology of an upsurge in invasive GAS (iGAS) infections in Ireland, 2012-2015 was investigated. METHODS Epidemiological typing of iGAS (n = 473) isolates was performed and compared to non-invasive (n = 517) isolates. Clinical data of notified iGAS was obtained from the national infectious disease information system. RESULTS Annual incidences of iGAS cases (n = 561) were 2.33-3.66 per 100,000 population. Bacteraemia was the most common clinical presentation (75%) followed by focus without bacteraemia (19%) and necrotizing faciitis (7%). Streptococcal toxic shock syndrome occurred in 19% of presentations. The main invasive emm types in rank order were emm1, emm3, emm28, emm12 and emm89 whereas emm4, emm28, emm3, emm12, emm89 and emm1 predominated in non-invasive infections. Invasive emm1 and emm3 showed annual fluctuations (15-48% and 4-37%, respectively) and predominated in most clinical presentations of iGAS. Superantigens speA, speG, speJ was associated with iGAS disease and, speC, speI and ssa with non-invasive infections. There was 4.3% erythromycin and 5.6% tetracycline resistance. The main resistant types were emm11, emm28 and emm77. CONCLUSIONS Cyclic increases in emm1 and emm3 occurred during the iGAS upsurge. Continued surveillance of GAS is therefore essential given the epidemiological changes that occur in a short time period.

Unexpected increase in invasive maternal Group B Streptococcus bacteraemia in a maternity hospital in Dublin, Ireland (May to September 2017) associated with subtle signs of sepsis and unreliable sepsis biomarkers

Journal of Infection - In Press.Proof corrected by the author Available online since mercredi 31 janvier 2018

Screening for early-onset invasive group B Streptococcal disease in neonates in an Irish hospital (2001–2014): a retrospective audit

Abstract Group B Streptococcus (GBS) is the most common cause of early-onset neonatal sepsis and meningitis. In babies with no clinical suspicion of infection, who are at risk of early-onset invasive disease based on maternal risk factors, blood cultures are taken to detect bacteraemia. In our institution, lumbar punctures are performed in infants with clinical signs of sepsis but not in infants who are well at the time of screening. Between 2001 and 2014, there were 112,361 live births weighing >500 g, of whom 13,959 (12.4%) infants had a blood culture taken on the first or second day of life, and 1971 (14.1%) of these infants had lumbar punctures on these first two days of life. Fifty-three cases of early-onset GBS disease were identified. Only three patients with invasive GBS disease had no clinical suspicion for sepsis at the time of testing. Thus, the number of blood cultures taken to detect one case of GBS bacteraemia in an infant who is well at the time of testing was 3996.