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Biomedical subjects

G L Gilbert

Publications and source records attributed to G L Gilbert.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2001

Practical evaluation of molecular subtyping and phage typing in outbreaks of infection due to Salmonella enterica serotype typhimurium.

Identification and control of food-poisoning outbreaks due to salmonellosis depend on prompt microbiological diagnosis and subtyping to identify the causative strain. In Australia, Salmonella enterica subspecies enterica serotype typhimurium (S. typhimurium) is responsible for 40-70% of cases of human salmonellosis. Phage typing is the usual method of subtyping S. typhimurium, but on its own, has limitations. We compared it with three molecular subtyping methods using 100 isolates of S. typhimurium, representing four different phage types (PT 1, 9, 126 and 135) and comprising 74 isolates from three presumed outbreaks, 25 isolates from sporadic cases of salmonellosis and S. typhimurium ATCC 10428 (phage type 126). The isolates were divided into 11 subtypes by IS200 restriction fragment length polymorphism (RFLP) typing, four each by ribotyping and pulsed-field gel electrophoresis (PFGE) and 17 distinct strains using a combination of phage and molecular typing. Isolates from two presumed outbreaks were resolved into multiple strains, possibly explaining the failure to identify a common source for either during the original investigations. IS200 RFLP analysis was the most discriminatory and reproducible typing method. Several strains were identifiable within and shared between phage types 1, 9 and 126. Phage and IS200 RFLP typing together, would provide improved definition of S. typhimurium outbreaks.

Bacterial Typing Techniques↗
PubMed2000

Epidemiology of invasive pneumococcal disease in urban New South Wales, 1997-1999.

OBJECTIVES: To describe the serotypes, incidence and morbidity of invasive pneumococcal disease in urban New South Wales. DESIGN: Prospective laboratory surveillance. SETTING: Microbiology laboratories and hospitals in the Sydney, Hunter and Illawarra Statistical Divisions of NSW, June 1997 to May 1999. RESULTS: 1270 cases were identified in two years. Incidence of disease was highest in those aged < 2 years (96.4 per 100,000; 95% CI, 83.7-107.9) and > or = 85 years (100.1 per 100,000; 95% CI, 81.8-121.3). Incidence of disease increased significantly from the age of 60 years, compared with low rates in those aged 5-59 years. Underlying diseases predisposing to pneumococcal infection increased with age, from 4% (< 2 years) to 60% (> or = 65 years). A seven-valent conjugate vaccine would have covered 84.8% of serotypes in those aged 0-14 years, falling to 69% in those > or = 15 years. Penicillin resistance was significantly higher in the < 5 years group (19.0%) than in older people (14.6%). CONCLUSIONS: Incidence of invasive pneumococcal disease was higher in this study using active surveillance than in previous Australian studies. An effective sevenvalent conjugate pneumococcal vaccine could prevent more than 80% of cases in children aged < 5 years.

Adolescent↗
PubMed2000

Molecular genotyping of human Ureaplasma species based on multiple-banded antigen (MBA) gene sequences.

Ureaplasma urealyticum has been divided into 14 serovars. Recently, subdivision of U. urealyticum into two species has been proposed: U. parvum (previously U. urealyticum parvo biovar), comprising four serovars (1, 3, 6, 14) and U. urealyticum (previously U. urealyticum T-960 biovar), 10 serovars (2, 4, 5, 7-13). The multiple-banded antigen (MBA) genes of these species contain both species and serovar/subtype specific sequences. Based on whole sequences of the 5'-ends of MBA genes of U. parvum serovars and partial sequences of the 5'-ends of MBA genes of U. urealyticum serovars, we previously divided each of these species into three MBA genotypes. To further elucidate the relationships between serovars, we sequenced the whole 5'-ends of MBA genes of all 10 U. urealyticum serovars and partial repetitive regions of these genes from all serovars of U. parvum and U. urealyticum. For the first time, all four serovars of U. parvum were clearly differentiated from each other. In addition, the 10 serovars of U. urealyticum were divided into five MBA genotypes, as follows: MBA genotype A comprises serovars 2, 5, 8; MBA genotype B, serovar 10 only; MBA genotype C, serovars 4, 12, 13; MBA genotype D, serovar 9 only; and MBA genotype E comprises serovars 7 and 11. There were no sequence differences between members within each MBA genotype. Further work is required to identify other genes or other regions of the MBA genes that may be used to differentiate U. urealyticum serovars within MBA genotypes A, C and E. A better understanding of the molecular basis of serotype differentiation will help to improve subtyping methods for use in studies of the pathogenesis and epidemiology of these organisms.

Amino Acid Sequence↗
PubMed2000

Species identification and subtyping of Ureaplasma parvum and Ureaplasma urealyticum using PCR-based assays.

There is good evidence that the organism currently known as Ureaplasma urealyticum should be divided into two species-U. parvum (previously U. urealyticum biovar 1) and U. urealyticum (previously U. urealyticum biovar 2). In this study, we designed a series of primers, targeting the 16S rRNA gene and 16S rRNA-23S rRNA intergenic spacer regions, the urease gene subunits, and the 5' ends of the multiple-banded antigen (MBA) genes, to identify and subtype these Ureaplasma species. All of the species-specific primer pairs could distinguish the two species, but only subtype-specific primer pairs targeting the MBA genes could distinguish subtypes within each species. U. parvum was separated into three subtypes, represented by serovars 1, 3/14, and 6. U. urealyticum was also separated into three subtypes by PCR and/or direct sequencing. Subtype 1 consisted of serovars 2, 5, 8, and 9; subtype 2 contained serovars 4, 10, 12, and 13; and subtype 3 contained serovars 7 and 11. A selection of primer pairs was used to identify and subtype 78 clinical ureaplasma isolates from vaginal swabs of pregnant women and to identify and subtype ureaplasmas directly in 185 vaginal swabs in which they had been previously detected. U. parvum was identified in 228 (87%) of 263 isolates or specimens, and U. urealyticum was identified in 50 (19%) (both were present in 6%). Serovars 3/14 (48%) and 1 (43%) were most common among U. parvum isolates, and subtypes 2 (62%) and 1 (34%) were most common among U. urealyticum isolates. This new PCR-based typing system will facilitate future studies of the relationship between individual Ureaplasma species or subtypes and human disease.

Antigens, Bacterial↗
PubMed2000

Parvovirus B19 infection and its significance in pregnancy.

Parvovirus B19 causes prolonged epidemics of erythema infectiosum, particularly in primary school-aged children. Infection causes clinically significant anaemia in individuals with high red cell turnover, including the fetus. Approximately 40% of women of childbearing age are susceptible, and annual seroconversion rates vary from 1.5% during endemic periods to 10-15% during epidemics. Infection occurs in around 50% of susceptible women exposed at home and 20-30% following occupational exposure (for example, at a primary school). Maternal infection in the first half of pregnancy is associated with 10% excess fetal loss and hydrops fetalis in 3% of cases (of which up to 60% resolve spontaneously or with appropriate management). No congenital abnormalities or long-term sequelae have been attributed to parvovirus B19 infection. The overall risk of serious adverse outcome from occupational exposure to parvovirus B19 infection during pregnancy is low (excess early fetal loss in 2-6/1,000 pregnancies and fetal death from hydrops in 2-5/10,000 pregnancies). It is not recommended that susceptible pregnant women be excluded routinely from working with children during epidemics.

Adult↗
PubMed1999

Culture shock. Molecular methods for diagnosis of infectious diseases.

Nucleic acid detection methods, such as polymerase chain reaction (PCR), can often detect specific microbial pathogens, virulence markers and antimicrobial resistance genes more rapidly and with greater sensitivity and specificity than culture and conventional identification and susceptibility testing. Multiplex PCR can detect multiple genes in a single assay; this capability will be greatly extended by new techniques such as the DNA chip. However, limitations and pitfalls of nucleic detection methods remain.

DNA Primers↗
PubMed1999

Surgical wound infection surveillance: the importance of infections that develop after hospital discharge.

BACKGROUND: The aim of this study was to evaluate two methods of post-discharge surgical wound surveillance and to compare the incidence and outcomes of wound infections that develop prior to patients' discharge with those that develop after hospital discharge. METHODS: One thousand, three hundred and sixty inpatients who underwent major elective surgery in an 800-bed teaching hospital in western Sydney between February 1996 and July 1997 were followed prospectively. Pre-discharge wound surveillance was performed by clinical assessment by an independent researcher on the fifth (or later) postoperative day. Post-discharge wound surveillance was performed by a mail out of questionnaires completed independently by patients and surgeons. RESULTS: Overall, 138 wound infections were diagnosed (incidence 10.1%), of which fewer than one-third (n = 44) were diagnosed before discharge (average 10.4 days postoperatively) and the remainder (n = 94) after discharge (average 20.6 days postoperatively). Seven hundred and eighty-two (57.5%) post-discharge survey forms were returned by patients and 680 (50.0%) by surgeons. When forms were returned by both surgeons and patients for the same wound (641 cases), there was substantial agreement in diagnosing infection or no infection (kappa = 0.73). CONCLUSIONS: The majority of nosocomial surgical wound infections develop after the patients' discharge from hospital. A post-discharge surveillance programme including self-reporting of infections by patients and return of questionnaires by patients and surgeons is feasible in an Australian hospital setting. However, such a programme is labour and resource intensive and strategies to increase return of questionnaires are required.

Antibiotic Prophylaxis↗
PubMed1999

Mutations in rpoB gene and rifabutin susceptibility of multidrug-resistant Mycobacterium tuberculosis strains isolated in Australia.

Control of tuberculosis, the single largest killer among the infectious diseases, has been threatened by the emergence of multidrug-resistant Mycobacterium tuberculosis (MDRTB) infection due to the limited treatment options. Rifampicin (RIF) resistance is considered as a marker for MDRTB. The aim of this study was the detection of rpoB gene mutations and rifabutin resistance in MDRTB strains recently isolated in Australia by a line probe assay (INNO-LiPA Rif. TB, Innogenetics). Rifabutin and RIF susceptibility of 20 MDRTB and 16 RIF-sensitive M. tuberculosis complex clinical isolates were studied. The overall concordance of the line probe assay (LiPA) with phenotypic RIF susceptibility test was 96%. Seven distinct nucleotide substitutions were identified in 21 of 22 RIF-resistant isolates of diverse geographical origins, but in none of the RIF-sensitive strains. The majority (71%) of mutations occurred in the 526-533 codons and were associated with resistance to rifabutin and RIF. Of the RIF-resistant MDRTB strains, 18% appeared to be rifabutin-sensitive and produced delta S2 and delta S3 INNO-LiPA patterns. We conclude that amino acid substitutions at Asp516 and Ser522 in the rpoB gene in RIF-resistant M. tuberculosis predict rifabutin susceptibility for MDRTB. Use of the LiPA for RIF and rifabutin resistance may facilitate the rapid response required to limit the extent and severity of MDRTB transmission and infection.

Antibiotics, Antitubercular↗