Detection of Chlamydia trachomatis in genitourinary tract specimens using an automated enzyme-linked fluorescent immunoassay

BACKGROUND AND GOAL

The VIDAS Enzyme Linked Fluorescent Assay is a fully automated assay for the detection of Chlamydia trachomatis in clinical specimens. Because there is an increasing demand for automated assays for large volume laboratories and there is little performance data available, the authors evaluated the performance of the VIDAS enzyme linked fluorescent assay by comparing it with Chlamydiazyme and polymerase chain reaction.

STUDY DESIGN

Endocervical swabs from 330 women attending a hospital based obstetrics/gynecology clinic and 100 first void urine specimens from males attending a sexually transmitted disease clinic were tested by enzyme linked fluorescent assay, Chlamydiazyme, and polymerase chain reaction.

RESULTS

Fourteen of 330 endocervical specimens and 14 of 100 first void urine specimens were positive by Chlamydiazyme. Enzyme linked fluorescent assay detected 12 of 14 endocervical and 11 of 14 first void urine specimens. Compared with Chlamydiazyme, enzyme linked fluorescent assay had a sensitivity of 85.7% (12 of 14) for endocervical swabs and 76.9% (11 of 14) for first void urine specimens. Polymerase chain reaction detected an additional five endocervical and two first void urine specimens that had negative results by both enzyme linked fluorescent assay and Chlamydiazyme. All 7 were confirmed positive by polymerase chain reaction using a second primer set. Using an expanded gold standard of blocked Chlamydiazyme and confirmed polymerase chain reaction, enzyme linked fluorescent assay had a sensitivity of 63.2% (12 of 19) for endocervical swabs and 68.8% (11 of 16) for first void urine specimens compared with 73.7% (14 of 19) and 87.5% (14 of 16) for Chlamydiazyme. Polymerase chain reaction had a sensitivity of 100% (19 of 19) and 93.8% (15 of 16) for endocervical swabs and first void urine specimens, respectively. The specificity of enzyme linked fluorescent assay and Chlamydiazyme was 100%.

CONCLUSIONS

The VIDAS enzyme linked fluorescent assay for the detection of Chlamydia trachomatis in genitourinary specimens is highly specific but is not sufficiently sensitive for use as a routine diagnostic test.

Ectopic cyclin E expression induces premature entry into S phase and disrupts pattern formation in the Drosophila eye imaginal disc

During animal development, cell proliferation is controlled in many cases by regulation of the G1 to S phase transition. Studies of mammalian tissue culture cells have shown that the G1-specific cyclin, cyclin E, can be rate limiting for progression from G1 to S phase. During Drosophila development, down-regulation of cyclin E is required for G1 arrest in terminally differentiating embryonic epidermal cells. Whether cyclin E expression limits progression into S phase in proliferating, as opposed to differentiating, cells during development has not been investigated. Here we show that Drosophila cyclin E (DmcycE) protein is absent in G1 phase cells but appears at the onset of S phase in proliferating cells of the larval optic lobe and eye imaginal disc. We have examined cells in the eye imaginal epithelium, where a clearly defined developmentally regulated G1 to S phase transition occurs. Ectopic expression of DmcycE induces premature entry of most of these G1 cells into S phase. Thus in these cells, control of DmcycE expression is required for regulated entry into S phase. Significantly, a band of eye imaginal disc cells in G1 phase was not induced to enter S phase by ectopic expression of DmcycE. This provides evidence for additional regulatory mechanisms that operate during G1 phase to limit cell proliferation during development. These results demonstrate that the role of cyclin E in regulating progression into S phase in mammalian tissue culture cells applies to some, but not all, cells during Drosophila development.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence that the National Committee for Clinical Laboratory Standards disk test is less sensitive than the screen plate for detection of low-expression-class methicillin-resistant Staphylococcus aureus

A low-expression-class methicillin-resistant Staphylococcus aureus strain (strain 9302-2) was sent to 207 laboratories as part of the bacteriology component of the Laboratory Proficiency Testing Program of Ontario. An incorrect (susceptible) result was reported by 16 of 76 (21%) of laboratories that used the National Committee for Clinical Laboratory standards disk test, whereas 1 of 104 laboratories that used other methods reported an incorrect result (P < 0.05). Experiments showed discrepancies in the disk test results given by Mueller-Hinton agars from three manufacturers. We advise that laboratories should use a low expression-class methicillin-resistant S. aureus isolate as a control for the National Committee for Clinical Laboratory Standards disk test.

Distinct modes of cyclin E/cdc2c kinase regulation and S-phase control in mitotic and endoreduplication cycles of Drosophila embryogenesis

Drosophila cyclin E (DmcycE) is required in embryos for S phase of mitotic and endoreduplication cycles. Here, we describe regulatory differences characteristic for these two cell cycle types. While DmcycE transcript levels decline in DmcycE mutant cells programmed for mitotic proliferation, they are maintained and no longer restricted to transient pulses in DmcycE mutant cells programmed for endoreduplication. Moreover, DmcycE expression in endoreduplicating cells is down-regulated by ectopic expression of a heat-inducible cyclin E transgene. DmcycE expression in endoreduplicating tissues, therefore, is restricted by a negative feedback to the transient pulse triggering entry into S-phase. Conversely, during mitotic cycles, where S phase entry is not only dependent on cyclin E but also on progression through M phase, cyclin E and associated Dmcdc2c kinase activity are present throughout the cell cycle. Reinitiation of DNA replication during the G2 phase of the mitotic cell cycle, therefore, is prevented by cyclin E/Dmcdc2c kinase-independent regulation. Observations in cyclin A mutants implicate G2 cyclins in this regulation. Our results suggest molecular explanations for the different rules governing S phase during mitotic and endoreduplication cycles.

Peak nasal inspiratory flow--the plateau effect

To study the efficacy of peak nasal inspiration flow (PNIF) as a means of recording change in nasal patency 20 subjects were given increasing doses of intranasal xylometazoline. Nasal resistance (NR) and peak nasal inspiratory flow (PNIF) were measured in the resting state and after each xylometazoline administration. Successive increases in dose caused a progressive decrease in nasal resistance and an increase in PNIF but the change in peak nasal inspiratory flow (PNIF) was much less. Peak nasal inspiratory flow shows a plateau effect as nasal resistance decreases. The reasons for this plateau are discussed in terms of respiratory flow mechanics.

Decreased cholesteryl ester transfer protein (CETP) mRNA and protein and increased high density lipoprotein following lipopolysaccharide administration in human CETP transgenic mice

The plasma cholesteryl ester transfer protein (CETP) mediates the exchange of HDL cholesteryl esters (CE) and VLDL triglycerides leading to catabolism of HDL. There is some evidence that HDL ameliorates the toxicity of LPS, and LPS is known to influence several enzymes affecting HDL metabolism. Therefore, the effects of LPS on CETP and plasma lipoproteins were examined in human CETP transgenic mice. Administration of LPS to mice expressing a CETP transgene linked to its natural flanking sequences (NFR-CETP Tg) resulted in a rapid marked decrease in hepatic CETP mRNA and plasma CETP concentration. Corticosteroid injection produced a similar decrease in hepatic CETP mRNA and adrenalectomy abolished this response to LPS. LPS caused disproportionate reductions in plasma CETP activity compared to mass, and was found to be a potent inhibitor of CETP activity when added directly to plasma. LPS was injected into mice expressing (A) a human apoA-I transgene, (B) apoA-I and NFR-CETP transgenes, or (C) apoA-I and LPS-inducible metallothionein promoter-driven CETP transgenes, producing (A) minimal changes in HDL cholesterol, (B) decreased plasma CETP and increased HDL cholesterol, and (C) increased plasma CETP and decreased HDL cholesterol. Thus, LPS administration produces a profound decrease in hepatic CETP mRNA, primarily as a result of adrenal corticosteroid release. The decrease in plasma CETP activity after LPS administration may reflect both this effect as well as a direct interaction between CETP and LPS. The decrease of CETP in response to LPS has major effects on HDL levels, and may represent an adaptive response to preserve or increase HDL and thereby modify the response to LPS.

Gender effects on the distribution of the cholesteryl ester transfer protein in apolipoprotein A-I-defined lipoprotein subpopulations

Two subpopulations of apolipoprotein A-I-containing lipoproteins, those containing only apoA-I (LpA-I) and those containing both apoA-I and apoA-II (LpA-I/A-II), were isolated by immunoaffinity chromatography of plasma from 44 subjects, comprising four groups (male or female, with or without hyperlipidemia). ApoA-I-defined particles (LpAs) were assessed for their content of cholesteryl ester transfer protein (CETP) and for their ability to act as substrates for CETP. Although plasma CETP concentration was similar in all groups, the plasma concentration of LpA-I-associated CETP was significantly higher in females than in males (1.56 +/- 0.11 versus 0.93 +/- 0.13 mg/l, P < 0.05). In females, the major fraction of CETP was found in LpA-I, whereas in normolipidemic males CETP was evenly distributed between LpA-I and LpA-I/A-II, and in hyperlipidemic males the majority of CETP was found in LpA-I/A-II. In all groups, the percentage of CETP in LpA-I was correlated with the concentration of apoA-I in LpA-I (r = 0.64, P < 0.001). Native gradient gel electrophoresis of isolated LpAs showed that CETP was broadly distributed within different sized particles. LpA-I and LpA-I/A-II showed similar efficiency of CETP-mediated cholesteryl ester exchange with LDL. In conclusion, even though LpA-I has a much higher apparent affinity for CETP than LpA-I/A-II, both LpAs can bind CETP and act as equivalent CETP substrates in vitro. Thus, in subjects with low levels of LpA-I (notably hyperlipidemic males), most of the plasma neutral lipid exchange will involve LpA-I/A-II.(ABSTRACT TRUNCATED AT 250 WORDS)

Response to venepuncture for monitoring in primary schools

The feasibility and acceptability of collecting blood from children by venepuncture was assessed in a sample of 593 children from seven primary schools in Canterbury. Venepuncture is necessary to obtain blood for the measurement of haemoglobin, ferritin, and cholesterol in line with Department of Health surveys in England. Return of consent forms was 87%; 75% of parents in the total sample allowed their child to be tested. Response rates differed between schools. Only 4% of eligible children refused to participate at the time of testing. In 22 (3.7%) children a blood sample could not be obtained or the volume was insufficient for analysis. There was a significant difference in the failure rate between phlebotomists. Venepuncture in the school setting was technically feasible and acceptable. The reluctance of some groups in the community to participate may bias the sample.

Serum total cholesterol and ferritin and blood haemoglobin concentrations in primary schoolchildren

Serum total cholesterol and ferritin and haemoglobin concentrations were measured in blood samples obtained by venepuncture in 378 of 593 children aged 5-6 or 8-9 years from seven primary schools in Canterbury. This study formed part of an investigation to assess the feasibility of including a venepuncture procedure for monitoring purposes in primary schoolchildren. Although only one child had a very low haemoglobin concentration of 61 g/l, a large percentage, 25% in the rising 6 years and 7% in the rising 9 years, had concentrations between 100 and 115 g/l--that is, less than the reference fifth centile. Eight per cent had a serum ferritin concentration less than 8 micrograms/l. Cholesterol concentrations higher than 5.2 mmol/l were found in 20% of the 5-6 year olds and 23% of the 8-9 year olds, and in 19% of boys and 25% of girls. About 5% of children had cholesterol concentrations above 6 mmol/l. The number of children with anaemia, iron deficiency, and high cholesterol raises serious concerns about the nutritional and coronary heart disease risk of British children.

Cyclin E controls S phase progression and its down-regulation during Drosophila embryogenesis is required for the arrest of cell proliferation

Most cells of the dorsal epidermis exit from the mitotic cycle after division 16 in Drosophila embryogenesis. This exit is dependent on the down-regulation of Drosophila cyclin E (DmcycE) during the final mitotic cycle. Ectopic expression of DmcycE after the final mitosis induces entry into S phase and reaccumulation of G2 cyclins and results in progression through a complete additional cell cycle. Conversely, analyses in DmcycE mutant embryos indicate that cyclin E is required for progression through S phase of the mitotic cycle. Moreover, endoreplication, which occurs in late wild-type embryos in the same pattern as DmcycE expression, is not observed in the mutant embryos. Therefore, Drosophila cyclin E, which forms a complex with the Dmcdc2c kinase, controls progression through S phase and its down-regulation limits embryonic proliferation.

Should we routinely screen for Lyme disease in patients with asymmetrical hearing loss?

Asymmetrical sensorineural hearing loss is usually investigated thoroughly but a diagnosis is often elusive. It is important to identify any treatable causes. Lyme disease is a tick-borne infection caused by the spirochaete Borrelia burgdorferi, which has been shown to cause asymmetrical sensorineural hearing loss, and has been successfully treated. Its incidence varies regionally; it occurs where there is a suitable environment for the tick and its animal hosts. We conducted a prospective study of 100 patients with asymmetrical sensorineural hearing loss. Serological testing for Lyme disease was performed. One patient had positive serology, but there was no improvement in her hearing following antibiotic treatment. We cannot conclude that our patient's hearing loss was caused by Lyme disease. We suggest that routine screening is not cost effective in regions with a low incidence of Lyme disease.

Genes for the establishment and maintenance of lysogeny by the temperate coliphage 186

To identify the genes in coliphage 186 that are required for lysogeny, we isolated clear-plaque mutants. Complementation studies and DNA sequencing identified two genes, the cI gene for the immunity maintenance repressor and the cII gene, which is required only for the establishment of lysogeny. One mutant carried a change in the LexA-binding site controlling expression of the antirepression protein Tum.

Accuracy of reporting of methicillin-resistant Staphylococcus aureus in a provincial quality control program: a 9-year study

We report the results of a province-wide quality control program in which five methicillin-resistant Staphylococcus aureus strains were circulated to all Ontario laboratories (hospital, private, and public health laboratories) on nine occasions between 1980 and 1989. The level of expression of methicillin resistance in each of the isolates was determined by performing viable colony counts on serial dilutions of methicillin in agar, and each isolate was assigned to an expression class according to previous published criteria (A. Tomasz, S. Nachman, and H. Leaf, Antimicrob. Agents Chemother. 35:124-129, 1991). Over this time there was an improvement in the performance of laboratories in the recognition of three strains that were relatively easy to detect (strains B, C, and E). These strains were of expression class II, and 98% of laboratories reported correct identifications in 1986. Performance in identifying two strains (strains A and D) of expression class I remained poor. Strain A was circulated in two surveys in 1987 and 1989, and laboratories were sent a questionnaire requesting details of the methods used in those two surveys. The methods used by the laboratories were classified into three categories: disk diffusion, single-plate screening by agar incorporation, and automated methods, which included premanufactured MIC panels. Between the 1987 and 1989 surveys, there was no change in the performance of the disk diffusion test (60% correct on both occasions), but there was improvement in the sensitivity of the agar incorporation test (36% correct in 1987 and 84% correct in 1989) and in automated methods (43% correct in 1987 and 79% correct in 1989). Over a decade, there was overall improvement in the performance of laboratories in detecting easy-to-detect strains, but there were difficulties in detecting organisms of low expression class, and an organism of very low expression class should be designated as a control organism for routine testing of methicillin-resistant s. aureus isolates.

Cyclin-B homologs in Saccharomyces cerevisiae function in S phase and in G2

We have cloned four cyclin-B homologs from Saccharomyces cerevisiae, CLB1-CLB4, using the polymerase chain reaction and low stringency hybridization approaches. These genes form two classes based on sequence relatedness: CLB1 and CLB2 show highest homology to the Schizosaccharomyces pombe cyclin-B homolog cdc13 involved in the initiation of mitosis, whereas CLB3 and CLB4 are more highly related to the S. pombe cyclin-B homolog cig1, which appears to play a role in G1 or S phase. CLB1 and CLB2 mRNA levels peak late in the cell cycle, whereas CLB3 and CLB4 are expressed earlier in the cell cycle but peak later than the G1-specific cyclin, CLN1. Analysis of null mutations suggested that the CLB genes exhibit some degree of redundancy, but clb1,2 and clb2,3 cells were inviable. Using clb1,2,3,4 cells rescued by conditional overproduction of CLB1, we showed that the CLB genes perform an essential role at the G2/M-phase transition, and also a role in S phase. CLB genes also appear to share a role in the assembly and maintenance of the mitotic spindle. Taken together, these analyses suggest that CLB1 and CLB2 are crucial for mitotic induction, whereas CLB3 and CLB4 might participate additionally in DNA replication and spindle assembly.

Secretion of intravenously administered antibiotics in gastric juice: implications for management of Helicobacter pylori

AIMS

To study whether differences in eradication rates of antibiotics may be explained by differences in secretion of antibiotics in gastric juice.

METHODS

A single intravenous dose of either ampicillin 500 mg, erythromycin 500 mg, or metronidazole 500 mg was administered to four healthy Helicobacter pylori negative volunteers on different days. Antibiotic concentrations were measured in gastric juice before and every 10 minutes after administration of the drug for two hours and after one hour in serum.

RESULTS

No ampicillin was detected in gastric juice. Erythromycin concentrations in gastric juice showed considerable individual variation and reached maximum concentrations of 2.2-4.8 mcg/ml between 30 and 80 minutes after dosing. Metronidazole concentrations in gastric juice showed much less individual variation and maximum concentrations of 5-6 mcg/ml were reached within 30 minutes and remained high during the study period.

CONCLUSION

Metronidazole and erythromycin are secreted across the gastric mucosa, but ampicillin is not.

Expression Vectors for the Construction of Hybrid Ty-VLPs

The synthesis of recombinant proteins or protein domains in microbial, insect, or mammalian systems is now commonplace in molecular biology laboratories. The gene or gene fragment encoding the protein of interest is inserted into a specialized expression vector, flanked by efficient transcription and translation control sequences. The expression vector is then inserted into recipient cells and expression of the protein induced. The expressed protein then has to be purified from other cellular or medium components. Purification can be facilitated by expressing the recombinant protein as a fusion with a carrier protein that assembles into particulate structures. This approach has been developed using a protein encoded by the yeast retrotransposon Ty, which self-assembles into virus-like particles (VLPs) (1,2). Additional protein coding sequences can be fused to the carrier protein gene and expressed in yeast to produce hybrid Ty-VLPs (3,4). The physical characteristics of the VLPs have been exploited to produce a rapid purification procedure that is essentially generic for any hybrid construction. Hybrid VLPs can be used in many laboratory applications (see elsewhere in this vol), including the production of polyclonal and monoclonal antibodies, structure/function analyses, the detection of important antigenic determinants, and epitope mapping of monoclonal antibodies.

Inhibition of urease activity but not growth of Helicobacter pylori by acetohydroxamic acid

The in vitro effects of acetohydroxamic acid (AHA), a potent urease inhibitor, were studied to determine the effect on the urease activity and growth of 38 strains of Helicobacter pylori. AHA in concentrations of 50-1000 mg/l had a noticeably reversible inhibitory effect on the urease activity of the organism but no effect on growth.

A fission yeast B-type cyclin functioning early in the cell cycle

We have cloned a fission yeast gene, cig1+, encoding a 48 kd product that is most similar to cyclin B proteins. The cig1+ protein has a "cyclin box" approximately 40% identical to B-type cyclins of other species, but lacks the "destruction box" required for proteolysis of mitotic cyclins. Deletion of cig1+ had no observable effect on cell viability or progression through G2 or M phase, but instead caused a marked lag in the progression from G1 to S phase. G1 constituted approximately 70% of the cell cycle in cig1 deletion strains, as compared with less than 10% in cig1+ strains. Constitutive cig1+ overexpression was lethal, causing cessation of growth and arrest in G1. Expression of cig1+ failed to rescue an S. cerevisiae strain lacking CLN Start cyclins. Thus, cig1+ identifies a new class of B-type cyclin acting in G1 or S phase that appears to be functionally distinct from all previously described cyclin proteins.

Massive thyroid oncocytoma

A patient with a massive thyroid oncocytoma is presented. The symptoms of hoarseness and dysphagia were due to compression and were relieved by surgical excision of the tumour.

cdc25 M-phase inducer

In this paper, we have described the critical experiments leading to the discovery and analysis of the cdc25 M-phase inducer. We have shown that timing of mitosis is sensitive to the level of cdc25+ expression and that the cellular concentration of p80cdc25 increases as cells approach mitosis. From these observations we conclude that, in S. pombe, rate of accumulation of p80cdc25 plays an important role in determining the timing of mitosis. We postulate that under a given set of conditions, a critical level of p80cdc25 activity is required to undergo mitosis. The actual level that is required can vary depending on ploidy, growth rate, nutritional status of the cell, and perhaps other parameters. These signals may be monitored through the weel pathway leading to tyrosyl phosphorylation of p34cdc2. We have shown that p80cdc25 encodes a phosphate that acts by directly dephosphorylating the Tyr-15 residue of p34cdc2. Our studies strongly indicate that this aspect of the mitotic control network is generally conserved among eukaryotes. It is conceivable, however, that the mode of regulation of cdc25 activity may vary from species to species. Clearly, in S. cerevisiae the cdc25+ homolog, MIH1, in contrast to cdc25+, is not rate-limiting for M-phase onset. It will be important to determine whether the level of cdc25+ homologs in other organisms also oscillates during the cell cycle, or whether their activity is controlled by localization or posttranslational mechanisms, such as phosphorylation. Furthermore, our finding of more than one cdc25+ homolog in a single species suggests an additional level of complexity to the control of M-phase onset by cdc25 in higher eukaryotes that will require further investigation.

The accuracy of clinical findings and laparoscopy in pelvic inflammatory disease

The accuracy of clinical diagnosis for pelvic inflammatory disease was determined in 95 women who presented with pelvic pain to primary care physicians and then were referred to gynecologists. Laparoscopy or laparotomy with endometrial biopsy and fimbrial minibiopsy revealed that prevalence of pelvic inflammatory was 46% (44/95) and positive and negative predictive values of gynecologists were 74% (23/31) and 67% (43/64) (p = 0.0002). If histopathologic diagnosis was the standard, clinical accuracies of the gynecologists were no better than chance (p = 0.43), suggesting an expectation bias for visual diagnosis. Laparoscopy had a sensitivity of 50% (12/24) and a specificity of 80% (40/50) for salpingitis if the standard was fimbrial histopathologic diagnosis (p = 0.01). These results support the routine use of laparoscopy, supplemented when negative by endometrial and fimbrial minibiopsy, to accurately diagnose pelvic inflammatory disease.

A rapid method for detection of group B streptococcal colonization: testing at the bedside

Vertical transmission of group B streptococci, the most frequent cause of early neonatal sepsis, can be interrupted by intrapartum antibiotics. However, rapid methods for detecting colonized women must be developed to limit the administration of antibiotics to those who are at risk of delivering an infected infant. The accuracy of a colorimetric test using starch serum medium on vaginal and rectal specimens from women with preterm labor or prolonged rupture of membranes was evaluated. The test was interpreted by labor and delivery room nurses without special microbiologic training. Starch serum medium results were compared with those obtained from routine cultures. Thirteen of 29 positive vaginal cultures (45%) and eight of 18 positive rectal swabs (44%) were identified by nurses using the rapid method. This was significantly different (P less than .001) from sensitivities of 93 and 95%, respectively, for the same vaginal and rectal specimens interpreted by a bacteriology technologist. The specificity for the test from both sites was 95% for the nurses. The sensitivity was 53 and 36% for vaginal and rectal swabs, respectively, for a subgroup of mothers whose infants were assessed as clinically septic. The low sensitivity of starch serum medium as interpreted by nurses in the labor suite is inadequate to allow the test to replace cultures in identifying women colonized with group B streptococci. Efforts to increase the sensitivity should be directed toward improving nursing staff interpretation rather than improving the medium itself.