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Biomedical subjects

G L Gilbert

Publications and source records attributed to G L Gilbert.

At least 19 recordsLinked to original sources
PubMed2004

Antibiotics for ureaplasma in the vagina in pregnancy.

BACKGROUND: Preterm birth is a significant obstetric problem in high-income countries. Genital infection including ureaplasmas are suspected of playing a role in preterm birth and preterm rupture of the membranes. Antibiotics are used to treat women with preterm prelabour rupture of the membranes and results in prolongation of pregnancy and lowers the risks of maternal and neonatal infection. However, antibiotics may be beneficial earlier in pregnancy to eradicate potentially causative agents. OBJECTIVES: The objective of this review is to assess whether antibiotic treatment of pregnant women with ureaplasma in the vagina reduces the incidence of preterm birth and other adverse pregnancy outcomes. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register (April 2003). SELECTION CRITERIA: All randomised controlled trials that compared any antibiotic regimen with placebo or no treatment in pregnant women with ureaplasma detected in the vagina. DATA COLLECTION AND ANALYSIS: Three reviewers independently assessed eligibility and trial quality and extracted data. MAIN RESULTS: One trial involving 1071 women was included. Of these, 644 randomly received antibiotic treatment (174 erythromycin estolate, 224 erythromycin sterate, and 246 clindamycin hydrochloride) and 427 received placebo. This trial did not report data on preterm birth. Incidence of low birthweight less than 2500 grams was only evaluated for erythromycin (combined) (n = 398 ) compared to placebo (n = 427) and there was no statistically significant difference between those treated and those not treated (relative risk (RR) 0.70, 95% confidence interval (CI) 0.46 to 1.07). In regards to side-effects sufficient to stop treatment, data were available for all women, and there were no statistically significant differences between any antibiotic (combined) and the placebo group (RR 1.25, 95% CI 0.85 to 1.85). REVIEWER'S CONCLUSIONS: There is insufficient evidence to show whether giving antibiotics to women with ureaplasma in the vagina will prevent preterm birth.

Anti-Bacterial Agents↗
PubMed2004

Temporal trends in circulating Bordetella pertussis strains in Australia.

Australia experienced a resurgence of pertussis in the 1990s despite improved vaccine coverage. Although much of the increase was attributable to increased detection of cases in older persons with waning immunity by serology, vaccine changes or alterations in circulating Bordetella pertussis strains may also have contributed. We determined the frequency of variants of B. pertussis pertactin (prn), and pertussis toxin subunit 1 (ptxS1) genes, restriction fragment length polymorphism (RFLP) types and fimbrial serotypes prevalent in Australia prior to, and during the 1990s. Ampoules of the whole-cell vaccine in use prior to 1999 and 84 B. pertussis isolates stored between 1967 and 1998 by laboratories around Australia were analysed. One pertactin allele, Prn3, not detected before 1985, was found in 24 out of 57 (42%) isolates between 1989 and 1998 (P<0.0001). PtxS1A was found in all isolates. IS1002 type 29, found in 17 out of 31 (55%) isolates tested, was the predominant RFLP type. The only difference in fimbrial serotype distribution between the time-periods was an increase in serotype 3 (P=0.054). The whole-cell vaccine contained only the alleles prn1 and ptxS1A. Antigenic shift in B. pertussis may have contributed to the re-emergence of pertussis in Australia. Monitoring these trends will be important as acellular vaccines are introduced and changes are made to pertussis vaccine schedules.

Bacteremia↗
PubMed2003

A large outbreak of influenza A and B on a cruise ship causing widespread morbidity.

In September 2000 an outbreak of influenza-like illness was reported on a cruise ship sailing between Sydney and Noumea with over 1,100 passengers and 400 crew on board. Laboratory testing of passengers and crew indicated that both influenza A and B had been circulating on the ship. The cruise coincided with the peak influenza period in Sydney. Morbidity was high with 40 passengers hospitalized, two of whom died. A questionnaire was sent to passengers 3 weeks after the cruise and 836 of 1,119 (75%) responded. A total of 310 passengers (37%) reported suffering from an influenza-like illness (defined as cough, fever, myalgia and weakness) and 528 (63%) had seen a doctor for illness related to the cruise. One-third of passengers reported receipt of influenza vaccination in 2000; however neither their rates of influenza-like illness nor hospitalization were significantly different from those in unvaccinated passengers. A case-control study also found no significant protective effect of influenza vaccination. With the increasing popularity of cruise vacations, such outbreaks are likely to affect increasing numbers of people. Whilst influenza vaccination of passengers and crew may afford some protection, uptake and effectiveness may not be sufficient to prevent outbreaks. Surveillance systems and early intervention measures, such as antiviral therapies, should be considered to detect and control such outbreaks.

Adult↗
PubMed2003

The seroepidemiology and transmission dynamics of varicella in Australia.

To enhance our understanding of the epidemiology and transmission dynamics of varicella in the pre-vaccine era we performed a serosurvey using opportunistically collected sera submitted to diagnostic laboratories across Australia during 1997-1999. A representative sample by state and sex of 2027 sera from persons aged 1-49 years was tested using an enzyme immunoassay method. The average age of infection and age-specific forces of infection (the probability that a susceptible individual acquires infection) were calculated using published methodologies. Seropositivity increased with age, with 83% of sera positive by ages 10-14 years. The highest force of infection was in the 5-9 years age group (0.195 per susceptible year) followed by the 0-4 years age group (0.139 per susceptible year) and the average age of infection was 8.15 years. These results provide valuable baseline information to measure the impact of vaccination and indicate that vaccination should be aimed at children less than 5 years of age, although further modelling using the serosurvey data is warranted.

Adolescent↗
PubMed2002

A mathematical model to measure the impact of the Measles Control Campaign on the potential for measles transmission in Australia.

BACKGROUND: The aims of this study were to determine the impact of the Australian Measles Control Campaign (MCC) on the transmission dynamics of measles by calculating the reproductive number (R) before and after the MCC, and to predict measles control in Australia in the future. METHODS: A national serosurvey was conducted before and after the MCC. Sera were tested for anti-measles IgG using enzyme immunoassay (EIA). A mathematical model, using serosurvey results and vaccine coverage estimates, was used to calculate the change in R after the MCC. RESULTS: The values of R calculated before and after the MCC were 0.90 and 0.57. At vaccine coverage levels indicated by the Australian Childhood Immunisation Register (ACIR), the value of R will exceed 1 (the epidemic threshold) in 2007-2008 nationally, and sooner in some regions of Australia. Coverage of at least 84% with two doses of MMR is required to sustain measles control. CONCLUSIONS: The Australian MCC had a significant impact on the transmission dynamics of measles. However, current vaccine coverage levels may result in indigenous measles transmission by 2007. Sustained efforts are required to improve coverage with two doses of MMR and to ensure elimination of indigenous measles transmission.

Adolescent↗
PubMed2002

Treat or test first? Decision analysis of empirical antiviral treatment of influenza virus infection versus treatment based on rapid test results.

BACKGROUND: neuraminidase (NA) inhibitors have recently become available for treatment of influenza. Rapid antigen detection assays at 'point-of-care' may improve the accuracy of clinical diagnosis, but the value of these techniques in assisting with the appropriate use of antivirals remains controversial. OBJECTIVE: to compare the diagnostic utilities of two management strategies for influenza, empirical antiviral therapy versus therapy based on a positive rapid test result in pre-epidemic and epidemic periods. STUDY DESIGN: a threshold decision analytic model was designed to compare these competing strategies and sensitivity analysis performed to examine the impact of diagnostic variables on the expected utility of the decision with a range of prior probabilities of infection between 1 and 50%. RESULTS: on the basis of the calculated sensitivity (77%) and specificity (95%) of a point-of-care test for influenza, pre-treatment testing was preferred and cost-effective in non-epidemic stage of the influenza cycle. The alternative strategy of empirical treatment produces a higher utility value during epidemics, but may result in overuse of antivirals for low-risk populations. The two strategies had equivalent efficacy when the probability of influenza was 42%. CONCLUSIONS: Patients with flu-like illness, who present outside the influenza outbreak and are considered to be at low risk for influenza-related complications, should be tested to confirm the diagnosis before starting antiviral treatment with a NA inhibitor. The most important variables in the model were the accuracy of the clinical diagnosis and the pre-test probability of influenza. A threshold probability of influenza of 42% would dictate changing from the rapid testing strategy to a 'treat regardless' strategy.

Antiviral Agents↗
PubMed2002

Serological diagnosis of pertussis: evaluation of IgA against whole cell and specific Bordetella pertussis antigens as markers of recent infection.

In Australia, notification of pertussis cases in older children or adults has increased significantly in recent years. In most cases, laboratory diagnosis is based only on a positive serological test for IgA antibody against whole cell Bordetella pertussis. During a 3-month period, 318 consecutive sera submitted for diagnosis of pertussis were tested for IgA antibody against whole cell (WC) sonicated B. pertussis, pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (PRN). Results of one or more of these tests were positive in sera from 175 subjects and clinical information was obtained by telephone interview from 90 subjects. Using a clinical case definition as the reference standard, the sensitivities of the four IgA assays were variable but quite low (24-64%), but the specificities were high (93-98%). For diagnosis of pertussis in subjects with a compatible clinical illness, these and other findings support the use of serological testing for IgA antibody.

Adolescent↗
PubMed2002

Epidemiology and predictive values of risk factors for neonatal group B streptococcal sepsis.

OBJECTIVES: To determine the incidence of and factors affecting risk factors for neonatal group B streptococcal (GBS) sepsis and their predictive values for intrapartum GBS carriage; to calculate the proportions of women eligible for intrapartum antibiotic prophylaxis (IAP) using different selection protocols. DESIGN: Cohort study. SETTING: Antenatal clinics and labour wards of a community hospital and a tertiary referral centre in western Sydney POPULATION: Women attending antenatal clinics during the study periods were invited to participate. METHODS: Approximately 500 women attending antenatal clinics were screened for GBS carriage at 26-32 weeks gestation and at delivery, using several screening methods. Clinical risk factors for neonatal sepsis were recorded during labour. MAIN OUTCOME MEASURES: Incidence of antenatal anovaginal GBS carriage and clinical risk factors during labour, their predictive values for intra-partum GBS carriage and their relationship, if any, to demographic and obstetric factors. RESULTS: Antenatal and intra-partum GBS carriage rates were similar but varied from 18% to 27%, depending on screening methods. The best positive and negative predictive values of antenatal GBS culture, for intra-partum carriage, were 69% (95% confidence interval (CI) 64-74) and 92% (95% CI 50-94) respectively Clinical risk factors occurred in similar proportions of GBS carriers and non-carriers. CONCLUSIONS: Neither early antenatal screening nor clinical risk factors are reliable predictors of intra-partum GBS carriage. Intra-partum antibiotic prophylaxis based on GBS carriage or risk factors when carrier status is unknown would involve approximately 35% of women, compared with approximately 16% if based on risk factors only Both strategies would prevent similar proportions of neonatal deaths from GBS sepsis. Compliance with a preventive protocol is the most likely determinant of its overall effectiveness.

Adult↗
PubMed2001

The Australian Measles Control Campaign, 1998.

The 1998 Australian Measles Control Campaign had as its aim improved immunization coverage among children aged 1-12 years and, in the longer term, prevention of measles epidemics. The campaign included mass school-based measles-mumps-rubella vaccination of children aged 5-12 years and a catch-up programme for preschool children. More than 1.33 million children aged 5-12 years were vaccinated at school: serological monitoring showed that 94% of such children were protected after the campaign, whereas only 84% had been protected previously. Among preschool children aged 1-3.5 years the corresponding levels of protection were 89% and 82%. During the six months following the campaign there was a marked reduction in the number of measles cases among children in targeted age groups.

Adolescent↗
PubMed2001

Hepatitis A epidemiology in Australia: national seroprevalence and notifications.

OBJECTIVES: To determine hepatitis A seroprevalence and notification rates in Australia in order to inform vaccination policy. DESIGN: Seroprevalence was determined by cross-sectional survey of opportunistically collected sera; notifications were extracted from the National Notifiable Diseases Surveillance System. PARTICIPANTS: 3,043 serum samples collected in 1998 were obtained from 46 laboratories around Australia. Sample size in each age group was based on expected seroprevalence, and States and Territories were sampled proportionally to their population size. Males and females were equally represented. Notifications were extracted for cases with onset between 1 January 1991 and 31 December 1998. MAIN OUTCOME MEASURES: Seroprevalence and notifications were analysed by age, sex and State/Territory. RESULTS: 41.1% of serum samples were seropositive for hepatitis A (95% CI, 39.4%-42.9%) (population-weighted seroprevalence, 38.3%). Seroprevalence was significantly associated with increasing age (P<0.001), but did not differ between the sexes (male:female ratio, 1.04:1; 95% CI, 0.95-1.14). However, significantly more notifications were recorded for males than females (male:female ratio, 1.65:1; 95% CI, 1.60-1.70). The Northern Territory had the highest seroprevalence (68.8%; 95% CI, 52.7%-84.8%) and annual notification rates (48.7 per 100,000 population; 95% CI, 45.0-52.4 per 100,000). CONCLUSIONS: These data show that about half the Australian population has not been exposed to hepatitis A and is therefore susceptible to infection. However, any decision on national routine childhood hepatitis A vaccination requires a cost-benefit analysis. Routine vaccination of high-incidence communities remains controversial.

Adolescent↗
PubMed2001

Antibiotic therapy of ventilator-associated pneumonia--a reappraisal of rationale in the era of bacterial resistance.

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in intensive care units (ICU). Resistance patterns seen in ICUs suggest that prescribing recommendations should be reappraised to limit practices engendering resistance to large families of antibiotics. Despite concern surrounding the use of antibiotics in the management of VAP, there is limited evidence to assist the clinician in making decisions about the indications for such therapy, the selection of the correct antibiotic(s), the timing of initiation of therapy and its duration. The high amount of antibiotic use, in combination with the low grade colonisation of patients with multi-resistant pathogens at the time of admission, turns the ICU into an environment where antibiotic policy is likely to have an effect on the resistance problem. Opinions are changing as to the validity of invasive techniques in guiding prescribing decisions. Invasive and semi-invasive diagnostic testing increases physician confidence in the diagnosis and management of VAP and helps to limit or discontinue antibiotic treatment.

Anti-Bacterial Agents↗
PubMed2001

Impact of the Australian Measles Control Campaign on immunity to measles and rubella.

To evaluate the impact of the 1998 Australian Measles Control Campaign on immunity to measles and rubella, 4400 opportunistically-collected sera, submitted to diagnostic laboratories across Australia from subjects aged 1-49 years, and 3000 from subjects aged 1-18 years, were tested before and after the campaign, respectively. The proportion of individuals aged 1-18 years who were immune to measles rose from 85% before, to 90% after, the campaign (P < 0.001). The greatest increase was in preschool (7%, P < 0.001) and primary school (10%, P < 0.001) children, who were actively targeted by the campaign. Rubella immunity in 1-18 year-olds rose from 83% to 91% (P < 0.0001), again with significant increases in preschool (4%, P = 0.002) and primary school (16%, P < 0.001) children. 94% of individuals aged 19-49 years were immune to rubella. These serosurveys confirm other evidence of the effectiveness of the Australian Measles Control Campaign and demonstrate the value of serosurveillance using opportunistically collected sera.

Adolescent↗
PubMed2001

What do physicians think about evidence-based antibiotic use in critical care? A survey of Australian intensivists and infectious disease practitioners.

BACKGROUND: The analysis of factors that influence prescribing decisions is increasingly important. Antibiotic use is often based on limited evidence and lack of information about clinical decision-making processes is an important obstacle to improving antibiotic utilization. AIMS: To compare the attitudes of intensive care unit practitioners (ICUP) and infectious disease practitioners (IDP) to antibiotic use and to the evidence-based information support. METHOD: A postal survey conducted between March and July 2000 of ICUP and IDP representing all States and Territories in Australia. RESULTS: One hundred and fifty-three of 224 clinicians returned the questionnaire (68.3% response rate). In choosing an antibiotic, IDP placed significantly more weight than ICUP on the in vitro susceptibility of the pathogen (P = 0.001), antibiotic cost (P = 0.05) and possible development of antibiotic resistance (P = 0.007). More than 95% of both groups believed that unit-specific antibiotic susceptibility of endemic pathogens was an essential factor in rational prescribing, but only 68.5% of IDP and 38.7% of ICUP use microbiology laboratory databases. When in doubt about appropriate antibiotic use, 63.8% of ICUP seek and 76.3% usually follow the advice of IDP. Both groups agree that published antibiotic guidelines are useful, but IDP were more likely to consult them. ICUP were more likely to believe that guidelines are used to control clinicians rather than to improve quality of care (P = 0.001). A greater proportion of IDP (71.2%) than ICUP (52.5%) believed that antibiotic prescribing in their intensive care unit (ICU) was evidence based but most (91.8% and 86.9%, respectively) agreed that it should be. CONCLUSIONS: Australian clinicians have positive views about evidence-based prescribing and antibiotic guidelines. However, there are clinically significant differences in prescribing behaviour between ICUP and IDP. These may be explained by different disease spectra managed by each group or different cultures, training and/or cognitive styles. Improvements in the understanding of physicians' information and decision support needs are required to strengthen evidence-based prescribing.

Anti-Bacterial Agents↗
PubMed2001

Species-specific PCR for identification of common contaminant mollicutes in cell culture.

Mycoplasma arginini, M. fermentans, M. hyorhinis, M. orale, and Acholeplasma laidlawii are the members of the class Mollicutes most commonly found in contaminated cell cultures. Previous studies have shown that the published PCR primer pairs designed to detect mollicutes in cell cultures are not entirely specific. The 16S rRNA gene, the 16S-23S rRNA intergenic spacer region, and the 5' end of the 23S rRNA gene, as a whole, are promising targets for design of mollicute species-specific primer pairs. We analyzed the 16S rRNA genes, the 16S-23S rRNA intergenic spacer regions, and the 5' end of the 23S rRNA genes of these mollicutes and developed PCR methods for species identification based on these regions. Using high melting temperatures, we developed a rapid-cycle PCR for detection and identification of contaminant mollicutes. Previously published, putative mollicute-specific primers amplified DNA from 73 contaminated cell lines, but the presence of mollicutes was confirmed by species-specific PCR in only 60. Sequences of the remaining 13 amplicons were identified as those of gram-positive bacterial species. Species-specific PCR primers are needed to confirm the presence of mollicutes in specimens and for identification, if required.

Cell Line↗
PubMed2001

Measles immunity in young Australian adults.

Previous state-based serosurveys and recent outbreaks have indicated that young adults may be at risk of measles. To provide a national picture of immunity in adults, we tested 2126 sera from 19-49 year olds that had been opportunistically collected from laboratories across Australia, between July 1996 and November 1998. Sera were stratified into age groups based on expected levels of immunity. Sample numbers were proportional to the population size in each State and Territory. Immunity was determined using an anti-measles IgG enzyme immunoassay (EIA) according to the manufacturer's instructions. Results were compared with those on sera from 2 groups of 1-18 year olds; one group collected before the Measles Control Campaign (conducted in the second half of 1998) and the other group collected after the Campaign. Immunity was highest (98.3%) in subjects aged at least 30 years (born before 1968) reflecting greater exposure to the measles virus in these older subjects. Immunity was lowest in those aged 1-6 years (born in 1994-8; 83.6%) and 18-22 years (born in 1974-80; 88.9%). The relatively low level of immunity in 18-22 year olds is probably due to lower vaccination coverage in this group compared with younger cohorts (aged 6-17 years). These results indicate the ongoing need to improve vaccine uptake in infants and suggest that a vaccination campaign targeting young adults would be beneficial.

Adult↗