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R W Peeling

Publications and source records attributed to R W Peeling.

At least 37 records · Page 2Linked to original sources
PubMed2002

The value of mass screening for chlamydia control in high prevalence communities.

The social context and epidemiology of STIs in remote communities in Northern Canada was examined. These communities have a persistently high reported incidence of gonorrhoea and chlamydial infection. They remain in the hyperendemic phase of the N. gonorrhoeae and C. trachomatis epidemics. They are ethnically and culturally homogeneous and contain no readily identifiable core groups, making it impossible to distinguish between spread and maintenance networks. Mass screening of the adult population can reduce the reservoir of C. trachomatis infection under these circumstances. It is particularly important to target men in settings such as this where women are routinely screened in antenatal and family planning clinics.

Adolescent↗
PubMed2001

Standardizing Chlamydia pneumoniae assays: recommendations from the Centers for Disease Control and Prevention (USA) and the Laboratory Centre for Disease Control (Canada).

Chlamydia pneumoniae has been associated with atherosclerosis and several other chronic diseases, but reports from different laboratories are highly variable and "gold standards" are lacking, which has led to calls for more standardized approaches to diagnostic testing. Using leading researchers in the field, we reviewed the available approaches to serological testing, culture, DNA amplification, and tissue diagnostics to make specific recommendations. With regard to serological testing, only use of microimmunofluorescence is recommended, standardized definitions for "acute infection" and "past exposure" are proposed, and the use of single immunoglobulin (Ig) G titers for determining acute infection and IgA for determining chronic infection are discouraged. Confirmation of a positive culture result requires propagation of the isolate or confirmation by use of polymerase chain reaction (PCR). Four of 18 PCR assays described in published reports met the proposed validation criteria. More consistent use of control antibodies and tissues and improvement in skill at identifying staining artifacts are necessary to avoid false-positive results of immunohistochemical staining. These standards should be applied in future investigations and periodically modified as indicated.

Bacteriological Techniques↗
PubMed2000

Surveillance for outbreaks of respiratory tract infections in nursing homes.

BACKGROUND: Outbreaks of respiratory tract infections are common in long-term care facilities for older people. The objective of our study was to determine both the frequency of such outbreaks and their clinical and epidemiological features. METHODS: Prospective surveillance for outbreaks of respiratory tract infections and a retrospective audit of surveillance records were conducted in 5 nursing homes in metropolitan Toronto over 3 years. The clinical manifestations of infected residents were identified and microbiological investigations for causal agents were conducted. RESULTS: Sixteen outbreaks, involving 480 of 1313 residents, were identified prospectively during 1 144 208 resident-days of surveillance, for an overall rate of 0.42 infections per 1000 resident-days. Another 30 outbreaks, involving 388 residents, were identified retrospectively. Outbreaks occurred year-round, with no seasonal pattern. Pathogens included influenza virus, parainfluenza virus, respiratory syncytial virus, Legionella sainthelensi and Chlamydia pneumoniae. Multiple pathogens were detected in 38% (6/16) of the prospectively identified outbreaks. Of the 480 residents in the prospectively identified outbreaks 398 (83%) had a cough, 194 (40%) had fever and 215 (45%) had coryza. Clinical findings were nonspecific and could not be used to distinguish between causal agents. Pneumonia developed in 72 (15%) of the 480 residents, and 58 (12%) required transfer to hospital. The case-fatality rate was 8% (37/480). INTERPRETATION: Our findings emphasize the importance of adequate surveillance for outbreaks of respiratory tract infections in nursing homes and of early diagnosis so that appropriate interventions can be promptly instituted.

Aged↗
PubMed2000

Serologic markers for Chlamydia pneumoniae in asthma.

BACKGROUND: Chlamydia pneumoniae infection has been reported as a possible etiologic agent in asthma, which in primary care settings often appears to be initiated by acute respiratory infections. OBJECTIVE: To determine if serologic markers for C. pneumoniae are associated with adult asthma that first became symptomatic after an acute respiratory illness (asthma associated with infection: AAWI). METHODS: Serum samples from 164 primary care outpatients, mean age 44 years, (68 with AAWI; 36 with atopic, occupational or exercise-induced asthma (non-AAWI); 16 nonasthmatic patients with acute bronchitis; and 44 asymptomatic nonasthmatic controls) were tested for the presence of C. pneumoniae-specific IgG and IgA antibodies. Levels of chlamydial heat shock protein 60 (CHSP60) antibody were also measured. Those positive for CHSP60 were tested for C. pneumoniae-specific IgE antibodies by immunoblotting. RESULTS: Statistically significant differences in IgG and IgA seroreactivity were noted between groups: acute bronchitis and AAWI had the highest levels (93% to 94% IgG seroreactivity, 69% to 75% IgA seroreactivity) whereas non-AAWI and asymptomatic controls had the lowest levels (61% to 84% IgG seroreactivity, 31% to 43% IgA seroreactivity, P < .02 after adjustment for age, sex and smoking). CHSP60 antibodies were significantly more prevalent in AAWI than in non-AAWI (19% versus 3%, P = .02). IgE antibodies against C. pneumoniae 60, 62, and/or 70 kD antigens were detected in 5 of 13 CHSP60 positive AAWI patients. Persistent IgG, IgA, and CHSP60 seroreactivities were noted in all seropositive asthma patients with serial serum samples. CONCLUSIONS: Serologic markers of C. pneumoniae infection were associated with acute bronchitis and with asthma that first became symptomatic following respiratory illness. Serologic responses to C. pneumoniae may be useful in the classification and diagnosis of asthma.

Adult↗
PubMed2000

Chlamydia pneumoniae serology: interlaboratory variation in microimmunofluorescence assay results.

The lack of standardization in chlamydia serology has made interpretation of published data difficult. This study was initiated to determine the extent of interlaboratory variation of microimmunofluorescence (MIF) test results for the serodiagnosis of Chlamydia pneumoniae infections. Identical panels of 22 sera were sent to 14 laboratories in eight countries for the determination of IgG and IgM antibodies by MIF. Although there was extensive variation in the numeric titer values, the overall percentage agreement with the reference standard titers from the University of Washington was 80%. For results by serodiagnostic category, the best agreement was for four-fold rise in IgG titers, while the lowest agreement was for negative or low IgG titers. Agreement for IgM titers was 50%-95%. Four laboratories failed to discern false-positive IgM titers possibly because of the presence of rheumatoid factor. Further studies are underway to determine the source of interlaboratory variation for the MIF test.

Antibodies, Bacterial↗
PubMed1999

Reproductive-tract infections in women in low-income, low-prevalence situations: assessment of syndromic management in Matlab, Bangladesh.

BACKGROUND: In the control of reproductive-tract infections, including sexually transmitted infections (STIs), in low-income and middle-income countries, WHO recommends syndromic management for individuals with symptoms. This intervention was initially developed in areas where prevalence of such infections is high. We investigated the clinical effectiveness and cost of this approach among a group of women with a low prevalence of infection. METHODS: During a 5-month period, we investigated all women complaining of abnormal vaginal discharge and seeking care at maternal and child health/family-planning centres in Matlab, Bangladesh, for the presence of laboratory-diagnosed reproductive-tract infections and STIs. Syndromic diagnoses made by trained health-care workers were compared with laboratory diagnosis of infection. We then calculated the costs of treating women by means of the recommended WHO algorithm and an adapted algorithm incorporating use of a speculum and simple diagnostic tests. FINDINGS: The prevalence of endogenous infections among 320 women seen was 30%. Cervical infections (Neisseria gonorrhoeae and Chlamydia trachomatis) were found in only three women. The WHO algorithm had a high sensitivity (100%) but a low specificity (zero for bacterial vaginosis, candida, and Trichomonas vaginalis). The speculum-based algorithm had a low sensitivity (between zero and 59%) but a higher specificity (79-97%). Between 36% and 87% of costs would have been spent on uninfected women. INTERPRETATION: The high rate of overtreatment in the population studied carries both financial and social costs--the latter in potentially exposing women misdiagnosed as having an STI to threats of domestic disruption or even violence. We make recommendations for management programmes in areas of low STI prevalence and low income.

Adolescent↗
PubMed1999

Analysis of the original antigenic sin antibody response to the major outer membrane protein of Chlamydia trachomatis.

The anamnestic antibody response to the Chlamydia trachomatis major outer membrane protein (MOMP) was evaluated in mice after priming with serovar C and boosting either with the homologous serovar or with heterologous serovars (A, H, K, and B). Microimmunofluorescence antibody responses demonstrated that boosting with heterologous serovars strongly recalled antibody to serovar C, typical of an original antigenic sin (OAS) response. Boosting with serovars antigenically related to serovar C (A, H, and K) recalled antibody to the variable domain 1 (VD1) peptide of the MOMP of serovar C as determined by a pin-peptide ELISA. Complete amino acid substitution analysis of the VD1 peptide epitope of the MOMP showed that the original antigenic sin response to each boosting serovar contained antibodies with unique patterns of VD1 peptide recognition. The data suggest that antigenically related C. trachomatis serovars differentially recruit B cell lineages from a heterogeneous memory B cell pool that had been induced by priming with the original serovar and thus account for the OAS antibody response.

Amino Acid Sequence↗
PubMed1999

Association of Chlamydia trachomatis heat-shock protein 60 antibody and HLA class II DQ alleles.

A total of 113 female commercial sex workers had individual alleles for HLA class II genes determined by using labeled sequence-specific oligonucleotide probes to hybridize to polymerase chain reaction products of amplified DNA. Women also had microimmunofluorescent (MIF) antibody titers to Chlamydia trachomatis elementary bodies and ELISA antibody to recombinant chlamydial heat-shock protein 60 (Chsp60) determined. Women were prospectively followed at monthly intervals over 2 years for incident C. trachomatis infection and acute pelvic inflammatory disease (PID). HLA DQA1*0401 and DQB1*0402 alleles were statistically associated with increased prevalence and amount of antibody to Chsp60 but not MIF antibody. However, these alleles did not alter the risk for chlamydial PID. The potential role that HLA DQ may play in chlamydial disease pathogenesis requires further study.

Antibodies, Bacterial↗
PubMed1999

Antibody response to the chlamydial heat-shock protein 60 in an experimental model of chronic pelvic inflammatory disease in monkeys (Macaca nemestrina).

A primate model of chlamydial pelvic inflammatory disease was used to characterize serum antibody responses to the 60 kDa chlamydial heat shock protein (CHSP60). Forty monkeys were infected in the fallopian tubes with Chlamydia trachomatis and then were treated. Twenty-three (58%) monkeys developed antibodies against CHSP60, of whom 6 (15%) had CHSP60 responses that persisted throughout the study and 17 (42.5%) had a transient response. A persistent CHSP60 antibody response was correlated with being culture- or ligase chain reaction-positive in the fallopian tubes (P=.004), but not in the cervix pretreatment, and with being tubal-positive posttreatment (P=. 02). Compared with tubal-negative monkeys, tubal-positive monkeys had more intense CHSP60 responses (P=.006) that lasted longer (P=. 002). Among CHSP60 responders, an OD>0.5 was correlated with more severe salpingeal pathology before treatment (P=.04). CHSP60 antibody response may be useful as a marker of persistent chlamydial infection in the fallopian tubes.

Animals↗
PubMed1998

Antibody response to the 60-kDa chlamydial heat-shock protein is associated with scarring trachoma.

To determine if serum antibody response to the 60-kDa chlamydial heat-shock protein (Chsp60) was associated with scarring trachoma, responses to Chlamydia trachomatis and to Chsp60 from 148 Gambian subjects with trachomatous scarring and from 148 controls without clinical evidence of disease from trachoma-endemic communities were characterized. Chsp60 response was found in 32% of cases and 16% of controls (P < .001). Although C. trachomatis titer was also higher in cases than controls, the prevalence of Chsp60 response between the 2 groups remained significantly different after stratifying for C. trachomatis titer (weighted odds ratio [OR] = 2.1, P = .02). Chsp60 response and C. trachomatis serovar A titer of > or =128 were independently associated with scarring trachoma. The presence of HLA class II allele DRB1*0701 was positively correlated with Chsp60 response (OR = 2.6, P = .02), and DQB1*0301 and DQB1*0501 were negatively associated (OR = 0.42, P < .001; OR = 0.55, P = .46, respectively).

Age Factors↗
PubMed1998

Pooling of urine specimens for PCR testing: a cost saving strategy for Chlamydia trachomatis control programmes.

OBJECTIVES: To evaluate pooling of first catch urine (FCU) specimens as a cost effective strategy for chlamydia testing. METHODS: Mock specimens were pooled with and without dilution to determine optimal pool size and ease of work flow. The performance of the Amplicor Chlamydia trachomatis PCR assay on pooled specimens was compared with individual testing using 370 FCU specimens from asymptomatic men presenting to an STD clinic. Cost savings associated with pooling were estimated. RESULTS: Using mock specimens, the sensitivity and specificity of the Amplicor PCR assay were not affected by pool sizes of two and five, but at a pool size of 10 decreased sensitivity due to inhibition was observed in one of five mock pools when the pooling method which involved no dilution was used. Archived FCU specimens from a study of 370 asymptomatic men were combined consecutively into 74 pools of five and tested by PCR. Of the 18 pools that contained positive specimens, 17 were PCR positive. Compared with testing FCU specimens individually, pooling resulted in a sensitivity of 95%, specificity of 100%, and a cost savings of 57% based on reduced number of tests required. CONCLUSION: Depending on the prevalence of infection, pooling of FCU specimens for PCR testing may result in cost savings compared with testing specimens individually. Further evaluations to validate this strategy using fresh FCU specimens are needed.

Bacteriological Techniques↗
PubMed1997

Chlamydia pneumoniae as a new source of infectious outbreaks in nursing homes.

OBJECTIVE: To determine the extent and severity of illness and mode of transmission of Chlamydia pneumoniae infection in 3 nursing home outbreaks. DESIGN AND SETTING: Retrospective cohort study in 3 nursing homes in Ontario from September to November 1994. SUBJECTS: A total of 549 residents and 65 staff members. MAIN OUTCOME MEASURES: Morbidity and mortality were determined by a review of disease surveillance forms, residents' charts, and a self-administered questionnaire to staff. Single and paired serum samples for C pneumoniae serological testing and nasopharyngeal swabs for C pneumoniae culture were collected, and direct fluorescent antibody assays were performed to confirm C pneumoniae infection. RESULTS: The attack rates for confirmed and suspected cases combined were 68%, 46%, and 44% among residents in nursing homes A, B, and C, respectively, and 34% among nursing home C staff. A total of 16 cases of pneumonia confirmed by chest x-ray and 6 deaths were identified. The spectrum of illness among nursing home C residents included a new cough in 58 (100%), fever in 37 (64%), sore throat in 14 (24%), and hoarseness in 8 (14%). Staff members at nursing home C were more likely to report hoarseness (P<.001) and sore throat (P<.001). Residents who smoked had onset of illness earlier than nonsmokers (P=.007), which perhaps is related to airborne transmission in a designated smoking room. CONCLUSIONS: Chlamydia pneumoniae caused serious morbidity and mortality among residents and morbidity among staff; C pneumoniae is an important cause of respiratory disease outbreaks in nursing homes, and diagnostic tests must be readily available for early recognition of C pneumoniae infections.

Aged↗
PubMed1997

Reliability of cytology to detect chlamydial infection in asymptomatic women.

Chlamydia trachomatis is a frequent sexually transmitted disease. The diagnosis of C. trachomatis infection by cytology is controversial. We compared the ability of Papanicolaou (Pap) smears to detect C. trachomatis infection with antigen detection (enzyme immunoassay; EIA) and polymerase chain reaction (PCR). One hundred sixty-seven women attending a therapeutic abortion clinic were enrolled in the study. Endocervical samples were first collected for EIA and PCR, and then Pap smears were prepared for cytologic evaluation. Eight patients were excluded from the study due to the lack of an endocervical component. The criteria established by Gupta and associates (Diagn Cytopathol 1988;4:224-229; Acta Cytol 1979;23:315-320) were used in this study to assess the specificity and sensitivity of the Pap smear in recognizing C. trachomatis infection. After EIA testing, the remaining sample was subjected to phenol-chloroform extraction to purify the DNA and then tested by PCR. Positive PCR samples were subjected to repeat phenol-chloroform and retested to confirm the positive result. Using a confirmed PCR or a blocked EIA as the extended gold standard, the incidence of C. trachomatis infection was 9.4%. Fifteen of the 159 cases reviewed were positive by extended gold standard. Thirteen (86.7%) of those 15 cases were interpreted as negative by cytology (false-negatives), and two (13.3%) cases were positive. Of the remaining 144 cases, 14 cases (9.7%) were interpreted as positive by cytology (false-positives) but were not confirmed by the extended gold standard. Ten (66.7%) of the 15 cases confirmed by the extended gold standard were interpreted as negative by EIA (false-negatives), and five (33.3%) were positive. There were no false-positives by EIA. In this study, the sensitivity and the specificity for cytology were 13.3% and 90.3%, respectively. The positive predictive value was 12.5%, and the negative predictive value for cytology was 90.9%. The sensitivity and the specificity for EIA were 33.3% and 100%, respectively. The positive predictive value was 100%, and the negative predictive value for EIA was 93.5%. Both EIA and cytology are insensitive methods compared with PCR. Based on these data, cytology should not be used to diagnose C. trachomatis infection in an asymptomatic female population with a moderate risk of C. trachomatis infection.

Chlamydia Infections↗
PubMed1997

Antibodies to the chlamydial 60 kd heat-shock protein are associated with laparoscopically confirmed perihepatitis.

OBJECTIVE: Our purpose was to examine clinical, microbiologic, serologic, and laparoscopic findings associated with perihepatitis. STUDY DESIGN: In a prospective study of 157 women with a clinical diagnosis of pelvic inflammatory disease, 27 women with laparoscopically confirmed perihepatitis and salpingitis were compared with 46 patients with salpingitis alone. RESULTS: Both current use or a history of ever using oral contraceptives was negatively associated with perihepatitis (p = 0.05 and p = 0.008, respectively). Moderate-to-severe pelvic adhesions were present at laparoscopy significantly more often in the perihepatitis-salpingitis group (70%) than in the salpingitis alone group (35%, p = 0.003). Antibody to the chlamydial 60 kd heat-shock protein at > or =0.5 optical density was detected in 67% of the perihepatitis-salpingitis group and in 28% of the salpingitis alone group (p = 0.005), and the median titer was significantly higher in the former group (p = 0.02). CONCLUSION: Compared with women with salpingitis alone, patients with perihepatitis-salpingitis do not have distinctive clinical or microbiologic findings but do manifest a higher prevalence of moderate-to-severe pelvic adhesions and both a higher prevalence and higher titers of antibody to the chlamydial heat-shock protein-60.

Adult↗