Biomedical subjects

Helen M McDonald

Publications and source records attributed to Helen M McDonald.

5 recordsLinked to original sources

PubMed2005

Antenatal screening for Group B Streptococcus: a diagnostic cohort study.

BACKGROUND: A range of strategies have been adopted to prevent early onset Group B Streptococcal (EOGBS) sepsis, as a consequence of Group B Streptococcal (GBS) vertically acquired infection. This study was designed to provide a scientific basis for optimum timing and method of GBS screening in an Australian setting, to determine whether screening for GBS infection at 35-37 weeks gestation has better predictive values for colonisation at birth than screening at 31-33 weeks, to examine the test characteristics of a risk factor strategy and to determine the test characteristics of low vaginal swabs alone compared with a combination of perianal plus low vaginal swabs per colonisation during labour. METHODS: Consented women received vaginal and perianal swabs at 31-33 weeks gestation, 35-38 weeks gestation and during labour. Swabs were cultured on layered horse blood agar and inoculated into selective broth prior to analysis. Test characteristics were calculated with exact confidence intervals for a high risk strategy and for antenatal screening at 31-33 and 35-37 weeks gestation for vaginal cultures alone, perianal cultures alone and combined low vaginal and perianal cultures. RESULTS: The high risk strategy was not informative in predicting GBS status during labour. There is an unequivocal benefit for the identification of women colonised with GBS during labour associated with delaying screening until 36 weeks however the results for method of screening were less definitive with no clear advantage in using a combined low vaginal and perianal swabbing regimen over the use of a low vaginal swab alone. CONCLUSION: This study can contribute to the development of prevention strategies in that it provides clear evidence for optimal timing of swabs. The addition of a perianal swab does not confer clear benefit. The quantification of advantages and disadvantages provided in this study will facilitate communication with clinicians and pregnant women alike.

Journal Article↗

PubMed2005

Polymorphisms in immunoregulatory genes and the risk of histologic chorioamnionitis in Caucasoid women: a case control study.

BACKGROUND: Chorioamnionitis is a common underlying cause of preterm birth (PTB). It is hypothesised that polymorphisms in immunoregulatory genes influence the host response to infection and subsequent preterm birth. The relationship between histologic chorioamnionitis and 22 single nucleotide polymorphisms in 11 immunoregulatory genes was examined in a case-control study. METHODS: Placentas of 181 Caucasoid women with spontaneous PTB prior to 35 weeks were examined for histologic chorioamnionitis. Polymorphisms in genes IL1A, IL1B, IL1RN, IL1R1, tumour necrosis factor (TNF), IL4, IL6, IL10, transforming growth factor beta-1 (TGFB1), Fas (TNFRSF6), and mannose-binding lectin (MBL2) were genotyped by polymerase chain reaction and sequence specific primers. Multivariable logistic regression including demographic and genetic variables and Kaplan-Meier survival analyses of genotype frequencies and pregnancy outcome were performed. RESULTS: Sixty-nine (34%) women had histologic evidence of acute chorioamnionitis. Carriage of the IL10-1082A/-819T/592A (ATA) haplotype [Multivariable Odds ratio (MOR) 1.9, P = 0.05] and MBL2 codon 54Asp allele (MOR 2.0, P = 0.04), were positively associated with chorioamnionitis, while the TNFRSF6-1377A/-670G (AG) haplotype (MOR 0.4, P = 0.03) and homozygosity for TGFB1-800G/509T (GT) haplotype (MOR 0.2, P = 0.04) were negatively associated. CONCLUSION: These findings demonstrate that polymorphisms in immunoregulatory genes IL10, MBL2, TNFRSF6 and TGFB1 may influence susceptibility to chorioamnionitis.

Journal Article↗

PubMed2004

Cerebral palsy and placental infection: a case-cohort study.

BACKGROUND: The association between cerebral palsy in very preterm infants and clinical, histopathologic and microbiological indicators of chorioamnionitis, including the identification of specific micro-organisms in the placenta, was evaluated in a case-cohort study. METHODS: Children with a diagnosis of cerebral palsy at five years of age were identified from amongst participants in a long-term follow-up program of preterm infants. The comparison group was a subcohort of infants randomly selected from all infants enrolled in the program. The placentas were examined histopathologically for chorioamnionitis and funisitis, and the chorioamnionic interface was aseptically swabbed and comprehensively cultured for aerobic and anaerobic bacteria, yeast and genital mycoplasmas. Associations between obstetric and demographic variables, indicators of chorioamnionitis and cerebral palsy status were examined by univariate analysis. RESULTS: Eighty-two infants with cerebral palsy were compared with the subcohort of 207 infants. Threatened preterm labor was nearly twice as common among the cases as in the subcohort (p < 0.01). Recorded clinical choroamnionitis was similar in the two groups and there was no difference in histopathologic evidence of infection between the two groups. E. coli was cultured from the placenta in 6/30 (20%) of cases as compared with 4/85 (5%) of subcohort (p = 0.01). Group B Streptococcus was more frequent among the cases, but the difference was not statistically significant. CONCLUSIONS: The association between E. coli in the chorioamnion and cerebral palsy in preterm infants identified in this study requires confirmation in larger multicenter studies which include microbiological study of placentas.

Journal Article↗

PubMed2004

Interleukins-1, -4, -6, -10, tumor necrosis factor, transforming growth factor-beta, FAS, and mannose-binding protein C gene polymorphisms in Australian women: Risk of preterm birth.

OBJECTIVE: The purpose of this study was to examine the relationship between preterm birth and 22 single nucleotide polymorphisms in genes that encode cytokines and mediators of apoptosis and host defense. STUDY DESIGN: Two hundred two white women with a spontaneous preterm birth of <35 weeks of gestation were compared with 185 white women with term births. Genotyping was performed with polymerase chain reaction and sequence specific primers. Multivariable analyses included demographic and genetic variables. RESULTS: Alcohol (multivariable odds ratio, 2.3; P = .001] and substance use (multivariable odds ratio, 3.7; P = .01) were associated with preterm birth at <35 weeks of gestation. Smoking (multivariable odds ratio, 2.3; P = .03), haplotypes IL10 -1082A/-819T/-592A (multivariable odds ratio, 2.1; P = .04), tumor necrosis factor ( TNF )+488A/-238G/-308G (multivariable odds ratio, 2.4; P = .04), and IL4 -509C/C (multivariable odds ratio, 3.4; P = .02), and the presence of MBL2 codon 54Asp (multivariable odds ratio, 2.3; P = .02) were associated independently with preterm birth at <29 weeks of gestation. Homozygosity for IL10 -1082G/-819C/-592C haplotype (multivariable odds ratio, 1.9; P = .02) was more common in women with preterm premature rupture of membranes. CONCLUSION: Polymorphisms in immunoregulatory genes may influence susceptibility to preterm birth or premature rupture of membranes.

Adolescent↗

PubMed2003

Taking antenatal group B Streptococcus seriously: women's experiences of screening and perceptions of risk.

BACKGROUND: Early-onset group B streptococcal disease is a serious cause of neonatal morbidity and mortality. Although screening protocols for group B streptococcus are common, little is known of women's perceptions of this screening and the disease itself. The purpose of this study was to gain an understanding of women's experiences, knowledge, and perceptions about this bacteria and its screening. METHODS: Nine focus group interviews with 35 women explored their experiences and understanding of group B streptococcus screening. Transcribed interview data were interpreted to identify and articulate the women's experiences. RESULTS: Most women had little knowledge or understanding of group B streptococcus, obtaining their information largely from the stories or experiences of friends or family. Women struggled to understand the meaning and implications, both physical and "moral," of the disease for their baby and for themselves, clearly indicating both the subjective and statistical importance of the concept of risk for pregnant women. CONCLUSIONS: Group B streptococcus continues to be poorly understood by pregnant women who try to understand and weigh up its risks and implications so as to make the best decisions about screening. The women participated in screening ultimately, however, since it was seen to be patently "best for baby," relatively easy for them to undergo, and part of routine antenatal care.

Adult↗