Investigating the role of pneumococcal neuraminidase A activity in isolates from pneumococcal haemolytic uraemic syndrome

Streptococcus pneumoniae diseases are a rare but increasingly recognized trigger of atypical haemolytic uraemic syndrome (HUS) in young children and associated with a higher mortality rate than diarrhoea-associated HUS. This study aimed to determine the importance of neuraminidase A (NanA) and genomic diversity in the pathogenesis of pneumococcal HUS (pHUS). We investigated the nanA gene sequence, gene expression, neuraminidase activity and comparative genomic hybridization of invasive pneumococcal disease (IPD) isolates from patients with pHUS and control strains matched by serotype and sequence type (ST), isolated from patients with IPD but not pHUS. The nanA sequence of 33 isolates was determined and mutations at 142 aa positions were identified. High levels of diversity were observed within the NanA protein, with mosaic blocks, insertions and repeat regions present. When comparing nanA allelic diversity with ST and disease profile in the isolates tested, nanA alleles clustered mostly by ST. No particular nanA allele was associated with pHUS. There was no significant difference in overall neuraminidase activity between pHUS isolates and controls when induced/uninduced with N-acetylneuraminic acid. Comparative genomic hybridization showed little difference in genetic content between the pHUS isolates and the controls. Results of gene expression studies identified 12 genes differentially regulated in all pHUS isolates compared with the control. Although neuraminidase enzyme activity may be important in pHUS progression and contribute to pathogenesis, the lack of a distinction between pHUS isolates and controls suggests that host factors, such as acquired abnormalities of the alternative complement cascade in young children, may play a more significant role in the outcome of pHUS.

Pregnancy outcome after elective cervical cerclage in relation to type of suture material used

Cervical weakness is an important cause of late miscarriage and extreme preterm labour. Women have been traditionally offered a cervical cerclage procedure, though studies failed to demonstrate a therapeutic effect. None of these studies has addressed the effect of non-braided to braided suture material on cerclage outcome. Type of suture material is an important determinant of surgical outcomes. This issue is of particular relevance to cerclage because the traditionally braided suture has been associated with increased risk of infection in other surgical procedures. Indeed, infection is an important underlying cause for cerclage failure. It is for this reason that some surgeons use non-braided suture material. Therefore, we hypothesise that the unrealised benefit of cervical cerclage is at least in part due to the type of suture material used. In this article, we present the rationale behind our hypothesis and a proposed way of testing it.

Bacterial bronchitis caused by Streptococcus pneumoniae and nontypable Haemophilus influenzae in children: the impact of vaccination

BACKGROUND

Protracted bacterial bronchitis is a major cause of persistent cough in childhood. The organisms most commonly isolated are nontypable Haemophilus influenzae and Streptococcus pneumoniae . There are no studies addressing typing of these organisms when recovered from the lower airways.

METHODS

Isolates of these two organisms (identified in BAL samples from children undergoing routine investigation of a chronic cough thought to be attributable to a protracted bacterial bronchitis) were subject to typing. Samples were collected in Sheffield, England, and Athens, Greece. The majority of the children from Sheffield had received pneumococcal-conjugate vaccines 7 or 13 (PCV-7 or PCV-13) conjugate vaccine but only a minority of Greek children had received PCV-7.

RESULTS

All 18 S pneumoniae isolates from Greek BAL samples are serotypes contained in PCV-13 while 10 are contained in PCV-7. In contrast, 28 of the 39 samples from Sheffield contained serotypes that are not included in PCV-13. All 26 of the nontypable H influenzae samples obtained in Sheffield produced distinct multilocus variable-number tandem repeat analysis profiles. There was a significant difference between children from Athens and Sheffield in the distribution of serotypes contained or not contained in the pneumococcal vaccine ( P = .04). More specifically, immunization with pneumococcal vaccine was related with isolation of S pneumoniae serotypes not included in the vaccine (OR, 0.021; CI, 0.003-0.115; P < .001).

CONCLUSIONS

The data suggest that both vaccine and nonvaccine S pneumoniae serotypes may play a role in protracted bacterial bronchitis and provide some hints that serotype replacement may occur in response to the introduction of conjugate vaccines.

A randomised controlled trial of abdominal versus laparoscopic sacrocolpopexy for the treatment of post-hysterectomy vaginal vault prolapse: LAS study

INTRODUCTION AND HYPOTHESIS

This prospective multi-centre true two-sided equivalence trial was designed to test the clinical equivalence of open (ASCP) and laparoscopic (LSCP) sacrocolpopexy using objective and subjective outcomes

METHODS

The study was carried out in three urogynaecology units in England, UK and the patient population consisted of women referred with symptomatic and bothersome post-hysterectomy vaginal vault prolapse at least 1 cm above or beyond the hymeneal remnants. The interventions were either abdominal or laparoscopic sacrocolpopexy following randomisation to one of the types of surgery.

RESULTS

For the primary outcome (point C on the POP-Q) the results at 1 year were -6.63 cm for the open ASCP and -6.67 cm for the LSCP respectively. Subjective outcomes at 1 year showed that 90% of the ASCP group and 80% of the LSCP group were "much better". There were improvements with regard to blood loss, haemoglobin and shorter length of stay in the LSCP group compared with the ASCP group.

CONCLUSION

This fully powered randomised controlled trial comparing open and laparoscopic sacrocolpopexy has shown clinical equivalence.

Serotype prevalence in adults hospitalised with pneumococcal non-invasive community-acquired pneumonia

BACKGROUND

The distribution of pneumococcal serotypes implicated in non-invasive community-acquired pneumonia (CAP) in adults is currently unknown.

METHODS

A prospective observational cohort study was conducted over 2 years in a large U.K. teaching hospital trust. Urine samples, in addition to routine blood and sputum samples, were obtained from consecutive adults admitted to the hospital with CAP. Pneumococcal serotype was determined from urine samples using a validated multiplex immunoassay which detects 14 serotypes.

RESULTS

Of 920 patients with CAP, 366 had pneumococcal CAP; 242 had a serotype determined. Thirty-day mortality was 10% for all-cause CAP and 9.6% for pneumococcal CAP. Annual incidence of pneumococcal CAP was 36.5 per 100,000, increasing from 12.1 to 274.1 per 100,000 for ages 16-44 years and ≥85 years, respectively. The most prevalent serotypes were 14, 1, 8, 3 and 19A. Less invasive serotypes were significantly associated with increasing age (OR per increasing age group: 1.5, 95% CI 1.2 to 1.9, p<0.001) and co-morbidity (OR per increasing Charlson index group: 1.4, 95% CI 1.0 to 2.0, p=0.036), and with higher 30-day mortality (OR adjusted for age and co-morbidity: 5.5, 95% CI 1.2 to 25.3, p=0.028) compared with highly invasive serotypes. The proportion of patients in whom serotypes contained within the seven-valent childhood pneumococcal conjugate vaccine was identified increased with age (15.6% for patients aged 16-44 years, 41.0% for patients aged ≥85 years; p<0.05).

CONCLUSIONS

In adult invasive and non-invasive pneumococcal CAP, the most common serotypes implicated were 14, 1, 8, 3 and 19A. Age and co-morbidity were associated with the distribution of serotypes identified.

Molecular typing methods for outbreak detection and surveillance of invasive disease caused by Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae, a review

Invasive disease caused by the encapsulated bacteria Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae remains an important cause of morbidity and mortality worldwide, despite the introduction of successful conjugate polysaccharide vaccines that target disease-associated strains. In addition, resistance, or more accurately reduced susceptibility, to therapeutic antibiotics is spreading in populations of these organisms. There is therefore a continuing requirement for the surveillance of vaccine and non-vaccine antigens and antibiotic susceptibilities among isolates from invasive disease, which is only partially met by conventional methods. This need can be met with molecular and especially nucleotide sequence-based typing methods, which are fully developed in the case of N. meningitidis and which could be more widely deployed in clinical laboratories for S. pneumoniae and H. influenzae.

Long term trends introduce a potential bias when evaluating the impact of the pneumococcal conjugate vaccination programme in England and Wales

A pneumococcal conjugate vaccine (PCV7) was introduced into the United Kingdom's childhood immunisation schedule in September 2006. Evaluation of its impact on the incidence of invasive pneumococcal disease (IPD) as assessed by routine reports of laboratory-confirmed cases should take into account possible long-term trends due to factors like changes in case ascertainment. To this end, we compared pre-PCV7 trends in reported IPD incidence in England and Wales identified by blood culture with those for two other bacteraemias, Escherichia coli and non -pyogenic streptococci, for which there has not been any public health intervention. While no trend was detected in the age group 65 years and older, there was an annual increase of 3% and 11% in those aged under five years and between five and 64 years, respectively, which was similar for IPD and the other two pathogens. After PCV7 introduction, a continuing trend was only found for non-pyogenic streptococci in under five year-olds. These trends in the incidence for bacteraemias for which there has been no intervention could suggest that there have been changes in case ascertainment because of increased reporting or blood culturing. Accounting for them will improve the evaluation of the impact of PCV7 on IPD.

Long term trends introduce a potential bias when evaluating the impact of the pneumococcal conjugate vaccination programme in England and Wales

A pneumococcal conjugate vaccine (PCV7) was introduced into the United Kingdom's childhood immunisation schedule in September 2006. Evaluation of its impact on the incidence of invasive pneumococcal disease (IPD) as assessed by routine reports of laboratory-confirmed cases should take into account possible long-term trends due to factors like changes in case ascertainment. To this end, we compared pre-PCV7 trends in reported IPD incidence in England and Wales identified by blood culture with those for two other bacteraemias, Escherichia coli and non -pyogenic streptococci, for which there has not been any public health intervention. While no trend was detected in the age group 65 years and older, there was an annual increase of 3% and 11% in those aged under five years and between five and 64 years, respectively, which was similar for IPD and the other two pathogens. After PCV7 introduction, a continuing trend was only found for non-pyogenic streptococci in under five year-olds. These trends in the incidence for bacteraemias for which there has been no intervention could suggest that there have been changes in case ascertainment because of increased reporting or blood culturing. Accounting for them will improve the evaluation of the impact of PCV7 on IPD.

Carbon monoxide re-breathing during low-flow anaesthesia in infants and children

BACKGROUND

Carbon monoxide (CO) has been detected within anaesthesia breathing systems. One potential source in this setting is exhaled endogenous CO. We hypothesized that CO is re-breathed during low-flow anaesthesia (LFA) in infants and children.

METHODS

Twenty children (age 2 months-7 yr) undergoing general anaesthesia were evaluated in a prospective observation study. LFA was established for 60 min followed by high-flow anaesthesia (HFA) for the next 60 min. Exhaled and inspired CO were measured every 5 min within the breathing circuit. Carboxyhaemoglobin (COHb%) was measured at baseline, at 60 min, after LFA, and at 120 min, after HFA.

RESULTS

CO concentrations increased during LFA. Inspired CO peaked at 14 ppm. During HFA, exhaled CO levels remained constant whereas inspired CO decreased markedly. Exhaled and inspired CO during HFA differed significantly from LFA. The trajectory of change in exhaled and inspired CO was most closely associated with the fresh-gas flow (FGF):minute ventilation ratio. COHb% significantly increased in children <2 yr of age at 60 min after LFA and remained increased.

CONCLUSIONS

LFA increased exhaled and inspired CO and increased COHb% in children <2 yr of age. Thus, LFA resulted in re-breathing of exhaled CO and exposure, especially in the youngest children. Re-breathing exhaled gas during LFA could pose a risk for an acute CO exposure in patients who have elevated COHb and high baseline levels of exhaled CO. If practitioners match or exceed minute ventilation with FGF to avoid LFA, CO re-breathing can be limited.

Host and environmental factors associated with Hib in England, 1998-2002

BACKGROUND

Declining effectiveness of the UK's Hib vaccine programme was observed between 1998 and 2002.

OBJECTIVE

To provide insight into non-vaccine factors contributing to ongoing Hib disease in England after immunisation.

DESIGN

Postal questionnaire study, matched case-control design.

SETTING

Health Protection Agency Centre for Infections, England.

PATIENTS

Cases were children born after 1 January 1993 presenting with confirmed Hib infection in England between the start of 1998 and end of 2002, regardless of vaccination status. Controls were matched by date of birth and region.

MAIN OUTCOME MEASURES

Odds ratios were calculated to assess the impact of host and environmental variables on disease risk.

RESULTS

Increased disease risk was noted among children with frequent antibiotic use (adjusted OR (AOR) (trend) 1.51 (95% CI 1.06 to 2.13); p = 0.02) and from sole-parent households (AOR 2.56 (95% CI 1.24 to 5.29); p = 0.01). These two risk factors were further related to each other, consistent with previously reported associations between infection and social deprivation. In fully immunised children, receipt of all three doses of the primary course as an acellular pertussis-containing combination vaccine (DTaP-Hib) increased the risk of vaccine failure (OR 2.88 (95% CI 0.99 to 8.37), p = 0.01). Day care attendance between 2 and 5 years of age was linked with a dose-dependent reduction in risk (AOR (trend) 0.79 (95% CI 0.66 to 0.93); p = 0.01), possibly because of natural boosting of immunity.

CONCLUSIONS

The association noted between invasive infection and social deprivation in this and other studies is concerning and merits further investigation. The importance of ongoing surveillance of vaccine-preventable diseases to allow nested studies of this kind was reinforced.

Vaginal surgery for pelvic organ prolapse using mesh and a vaginal support device

Objectives

To describe a new surgical procedure for pelvic organ prolapse using mesh and a vaginal support device (VSD) and to report the results of surgery.

Design

A prospective observational study

Setting

Two tertiary referral Urogynaecology practices.

Population

Ninety-five women with International Continence Society pelvic organ prolapse quantification stage 2 or more pelvic organ prolapse who underwent vaginal surgery using mesh augmentation and a VSD.

Methods

Surgery involved a vaginal approach with mesh reinforcement and placement of a VSD for 4 weeks. At 6 and 12 months, women were examined for prolapse recurrence, and visual analogue scales for satisfaction were completed. Women completed quality-of-life (QOL) questionnaires preoperatively and at 6 and 12 months.

Main outcome measures

Objective success of surgery at 6 and 12 months following surgery. Secondary outcomes were subjective success, complications, QOL outcomes and patients’ satisfaction.

Results

Objective success rate was 92 and 85% at 6 and 12 months, respectively. Subjective success rate was 91 and 87% at 6 and 12 months, respectively. New prolapse in nonrepaired compartments accounted for 7 of 12 (58%) failures at 12 months. Two of 4 mesh exposures required surgery. Sexual dysfunction was reported by 58% of sexually active women preoperatively and 23% at 12 months. QOL scores significantly improved at 12 months compared with baseline (P < 0.0001).

Conclusion

Vaginal surgery using mesh and a VSD is an effective procedure for pelvic organ prolapse. However, further studies are required to establish the role of the surgery described in this study.

Please cite this paper as:Carey M, Slack M, Higgs P, Wynn-Williams M, Cornish A. Vaginal surgery for pelvic organ prolapse using mesh and a vaginal support device. BJOG 2008;115:391–397.

The descriptive epidemiology of Streptococcus pneumoniae and Haemophilus influenzae nasopharyngeal carriage in children and adults in Kilifi district, Kenya

BACKGROUND

Transmission and nasopharyngeal colonization are necessary steps en route to invasive pneumococcal or Haemophilus influenzae disease but their patterns vary geographically. In East Africa we do not know how these pathogens are transmitted between population subgroups nor which serotypes circulate commonly.

METHODS

We did 2 cross-sectional nasopharyngeal swab surveys selecting subjects randomly from a population register to estimate prevalence and risk-factors for carriage in 2004. H. influenzae type b vaccine was introduced in 2001.

RESULTS

Of 450 individuals sampled in the dry season, 414 were resampled during the rainy season. Among subjects 0-4, 5-9, and 10-85 years old pneumococcal carriage prevalence was 57%, 41%, and 6.4%, respectively. H. influenzae prevalence was 26%, 24%, and 3.0%, respectively. Prevalence of H. influenzae type b in children <5 years was 1.7%. Significant risk factors for pneumococcal carriage were rainy season (odds ratio [OR]: 1.65), coryza (OR: 2.29), and coculture of noncapsulate H. influenzae (OR: 7.46). Coryza was also a risk factor for H. influenzae carriage (OR: 1.90). Of 128 H. influenzae isolates, 113 were noncapsulate. Among 279 isolates of Streptococcus pneumoniae, 40 serotypes were represented and the distribution of serotypes varied significantly with age; 7-valent vaccine-types, vaccine-related types, and nonvaccine types comprised 47%, 19%, and 34% of strains from children aged <5 years. Among older persons they comprised 25%, 28%, and 47%, respectively (P = 0.005).

CONCLUSIONS

The study shows that pneumococcal carriage is common up to 9 years of age and that the majority of serotypes carried at all ages are not covered specifically by the 7-valent pneumococcal conjugate vaccine.

Molecular epidemiology of Haemophilus influenzae type b causing vaccine failures in the United Kingdom

Haemophilus influenzae type b (Hib) was a major cause of pediatric disease in the United Kingdom prior to the introduction of routine Hib immunization in 1992. An unexpected resurgence of cases of vaccine failure was observed with fully vaccinated children from 1999 onward. We investigated whether Hib isolates causing vaccine failures in the United Kingdom could have undergone a change in their population structure to elude the protective effect of Hib vaccine. Molecular epidemiology studies were carried out with 376 isolates from invasive infections (164 vaccine failures and 212 controls). Genetic variability was higher in controls than in vaccine failures. Of the four major clusters obtained, cluster I comprised 92.2% of the total isolates: 156 vaccine failures (95%) and 193 (91%) controls. Cluster IV was specific for vaccine failures but included only four isolates. The increased number of cases of invasive Hib in fully vaccinated children in the United Kingdom was caused by isolates belonging not to a particular or new genotype but to genotypes already circulating in the prevaccination era, before conjugate Hib vaccines were available.