Invasive Group B Streptococcus Disease With Recurrence and in Multiples: Towards a Better Understanding of GBS Late-Onset Sepsis.

Group B Streptococcus (GBS) is a common intestinal colonizer during the neonatal period, but also may cause late-onset sepsis or meningitis in up to 0.5% of otherwise healthy colonized infants after day 3 of life. Transmission routes and risk factors of this late-onset form of invasive GBS disease (iGBS) are not fully understood. Cases of iGBS with recurrence (n=25) and those occurring in parallel in twins/triplets (n=32) from the UK and Ireland (national surveillance study 2014/15) and from Germany and Switzerland (retrospective case collection) were analyzed to unravel shared (in affected multiples) or fixed (in recurrent disease) risk factors for GBS disease. The risk of iGBS among infants from multiple births was high (17%), if one infant had already developed GBS disease. The interval of onset of iGBS between siblings was 4.5 days and in recurrent cases 12.5 days. Disturbances of the individual microbiome, including persistence of infectious foci are suggested e.g. by high usage of perinatal antibiotics in mothers of affected multiples, and by the association of an increased risk of recurrence with a short term of antibiotics [aOR 4.2 (1.3-14.2), P=0.02]. Identical GBS serotypes in both recurrent infections and concurrently infected multiples might indicate a failed microbiome integration of GBS strains that are generally regarded as commensals in healthy infants. The dynamics of recurrent GBS infections or concurrent infections in multiples suggest individual patterns of exposure and fluctuations in host immunity, causing failure of natural niche occupation.

Group B streptococcal disease in UK and Irish infants younger than 90 days, 2014-15: a prospective surveillance study.

BACKGROUND: Group B streptococcus is a leading cause of serious infection in young infants in many countries worldwide. We aimed to define the burden and clinical features of invasive group B streptococcal disease in infants younger than 90 days in the UK and Ireland, together with the characteristics of disease-causing isolates. METHODS: Prospective, active national surveillance of invasive group B streptococcal disease in infants younger than 90 days was done from April 1, 2014, to April 30, 2015, through the British Paediatric Surveillance Unit, microbiology reference laboratories, and national public health agencies in the UK and Ireland. Early onset was defined as disease in the first 6 days of life and late onset was defined as 7-89 days of life. Incidence was calculated using livebirths in 2014 (after adjustment for the 13-month surveillance period). Isolates were characterised by serotyping, multilocus sequence typing, and antimicrobial susceptibility testing. FINDINGS: 856 cases of group B streptococcus were identified in 2014-15, an incidence of 0·94 per 1000 livebirths (95% CI 0·88-1·00). Incidence for early-onset disease (n=517) was 0·57 per 1000 livebirths (95% CI 0·52-0·62), and for late-onset disease (n=339) was 0·37 per 1000 livebirths (0·33-0·41). 53 infants died (case fatality rate 6·2%), of whom 27 had early-onset disease (case fatality rate 5·2%) and 26 had late-onset disease (case fatality rate 7·7%). The predominant serotypes were III (241 [60%] of 402 serotyped isolates) and Ia (69 [17%]); five serotypes (Ia, Ib, II, III, V) accounted for 377 (94%) of all serotyped isolates. INTERPRETATION: The incidence of invasive infant group B streptococcal disease in the UK and Ireland has increased since a comparable study done in 2000-01. The burden of early-onset disease has not declined despite the introduction of national prevention guidelines. New strategies for prevention are required. FUNDING: Meningitis Now.

Variations due to analysis technique in intracellular pH measurements in simulated and in vivo 31P MR spectra of the human brain.

PURPOSE: To investigate variation in pH generated by different analysis techniques and to find the most robust method, 31P MR brain spectra were acquired in vivo. Three different methods were used to measure the chemical shift of inorganic phosphate (Pi) relative to phosphocreatine (PCr). MATERIALS AND METHODS: Eight healthy volunteers were scanned four times, and manual measurement of the chemical shift in a frequency domain spectrum using the manufacturer's software was compared with values produced by a frequency-domain analysis method (NMR1) and a prior-knowledge-based time-domain technique (MRUI). To explain the in vivo data, simulations of brain spectra, modified in ways typical of real variations in vivo, were produced and the pH was measured using manual measurement and MRUI. RESULTS: Different measurement techniques produced systematically different pH values, with manual measurement producing the lowest variability (manual measurement: pH = 6.999, CoV = 0.297; NMR1: pH = 7.042, CoV = 0.501; MRUI: pH = 7.036, CoV = 0.606). While MRUI more accurately measured the pH of unaltered simulations, it was systematically affected by altering the simulated spectra. Manual measurement was unaffected. CONCLUSION: Manual measurement produces the most consistent pH value, and there is no benefit in using more complex automated spectral fitting methods to measure the pH.