Rapid detection of HSV from cytologic specimens collected into ThinPrep fixative

Living the best of both worlds: A personal scientific journey

Opportunity is the essence of a career in science or medicine and this continues to be a major source of satisfaction for the many scientists and health care providers worldwide. Having trained as a PhD scientist, the world of clinical medicine seemed to be a galaxy away. I could not have been more wrong in that assumption. Here, I tell the story of my career trajectory so that those new to the sciences understand the potential and the opportunities afforded by a career in clinical laboratory medicine.

Herpes Simplex Virus Cervicitis Mimicking Preterm Premature Rupture of Membranes

BACKGROUND

The diagnosis of preterm premature rupture of membranes (PROM) is based on pooling, ferning, and Nitrazine tests; definitive diagnosis is made with a blue dye test.

CASE

A 21-year-old woman, gravida 1 para 0, at 25 5/7 weeks of gestation was admitted for preterm PROM with positive findings of pooling, Nitrazine, and ferning. Her cervix was bluish with white plaques. Amniotic fluid volume was normal. On hospital day 8, her discharge ceased; examination was negative for pooling, Nitrazine, and ferning. A blue dye tampon test was negative. A Pap test result from her hospitalization returned consistent with herpes infection.

CONCLUSION

The diagnosis of preterm PROM should be constantly reevaluated in the setting of a normal amniotic fluid volume.

Gynecologic cytology on conventional and liquid-based preparations: a comprehensive review of similarities and differences

Liquid-based preparations (LBPs) have largely replaced conventional Papanicolaou smears (CPS) for cervical samples in the United States and in many other industrialized countries. The two FDA-approved LBP currently in use include ThinPrep (TP), (Hologic Inc., Bedford, MA) and SurePath (SP), (BD Diagnostic, Burlington, NC). Split-sample and direct-to-vial studies have shown that LBPs show an overall improvement in sample collection and processing, reduce artifacts that interfere in diagnosis, are more sensitive, can be utilized for ancillary tests and are a cost-effective replacement for CPS. Comparative analyses of diagnostic accuracy indicate that LBPs perform at least as well as CPS. However, the added advantages of standardized, automated preparations and screening, reduced unsatisfactory rate, improved specimen adequacy and ability to perform human papillomavirus (HPV) test, are enough to continue use of LBP. The cytologic features in LBP are similar to CPS with subtle differences, particularly in background information. There are also subtle differences between the two LBPs, SP and TP, which are reflective of different sampling devices, collection media, and processing techniques. Architecturally, LBP shows smaller cell clusters and sheets and more dyscohesion. Cytologically, enhanced nuclear features and smaller cell size are more prominent. Advances in liquid-based Papanicolaou's (Pap) test have lead to well-defined patient management guidelines by the American Society for Colposcopy and Cervical Pathology. Herein, we review these aspects of Pap test including, morphology, automation, ancillary tests (HPV and immunochemistry), pertinent QA/QC monitors, patient management guidelines, and review of pertinent literature.

Value of centrifugated liquid-based cytology by Papanicolaou and May-Grünwald in oral epithelial cells

For many years, liquid-based cytology (LBC) has been developed for cervical cancer screening and not oral cancer, as it requires automated devices. The aim of this study was to compare the utility of centrifugated CLBC preparation with that of direct preparation in oral lesions, by Papanicolaou (Pap) and May Grünwald-Giemsa's (MGG) methods. A total of 100 consecutive cases of oral lesions were investigated. We compared the results obtained by the CLBC performed by cytocentrifugation with those obtained by direct smear applying Pap and MGG methods. The comparison between CLBC and direct smears was based on the thickening or adequacy of the smear, distribution of cells and staining quality. All smears in CLBC and direct preparation were found adequate. For thickness of the smear, 40% and 42% were excellent, 33% and 30% were good, and 27% and 28% were acceptable by LBC and direct preparation, respectively. For the distribution of cells and scantiness of background elements, 92 (92%) smears of the CLBC have revealed clear, well distributed smears, compared to 70 (70%) of those in direct preparation. For the staining quality with the Pap method, 39% and 69% were excellent staining quality, 25% and 20% were good, and 36% and 11% were acceptable for CLBC and direct preparation, respectively. In MGG method, 9% and 22% were excellent staining quality, 23% and 36% were good and 68% and 43% were acceptable for CLBC and direct preparation respectively. CLBC performed by cytocentrifugation is inexpensive, and reduces inadequate smears and background staining.

Assessment of Chlamydia trachomatis infection by Cobas Amplicor PCR and in-house LightCycler assays using PreservCyt and 2-SP media in voluntary legal abortions

Chlamydial infection of the upper genital tract after abortion is well recognized, but routine screening for infection before termination is rare, and few centres are aware of the prevalence of post-abortion complications in their patient population. Knowledge of the patient population is the best guide for developing screening strategies. The aim of this study was to determine the prevalence of chlamydial infection in patients presenting for legal termination of pregnancy, and to assess the presence of Chlamydia trachomatis by PCR on specimens collected in either PreservCyt (ThinPrep) or 2-sucrose phosphate (2-SP) transport medium. Two hundred and eleven single, sexually active women, aged 15-26 years, attending the Gynaecology and Obstetric Hospital, Amiens, France, for surgical termination of pregnancy were enrolled in this study from June 2002 to June 2003. C. trachomatis detection using a Cobas Amplicor PCR test (Roche Diagnostics) targeting a 207 bp segment of the common cryptic plasmid and a quantitative LightCycler real-time PCR (LC-PCR) (Roche Diagnostics) targeting a 123 bp fragment within the highly conserved constant domain 3 of the single-chromosome-copy ompA gene were performed on endocervical swabs in 2-SP, and on specimens collected using a cytobrush and placed in PreservCyt medium. The in-house LC-PCR was used as a chromosomal diagnosis method and to determine the load of C. trachomatis. This method was able to detect the mutant Swedish variant with a deletion of 377 bp in the target area in the cryptic plasmid, which is the region targeted by the Cobas Amplicor PCR test. C. trachomatis was detected in 19/211 patients (9 %) by both PCR methods. Among the 19 infected women, C. trachomatis was detected by the Cobas Amplicor PCR in 16 specimens in PreservCyt (7.6 %) and in 12 endocervical swabs in 2-SP (5.7 %). Specimens from only nine women were PCR-positive in both PreservCyt and 2-SP media by this method. Cobas Amplicor PCR revealed that 10.9 and 2.3 % of the PreservCyt and 2-SP samples, respectively, contained inhibitors. The same 19 infected women were LC-PCR positive in both PreservCyt and 2-SP samples. No additional infected women were found by this last method; thus, it was concluded that none of the samples contained the new variant of C. trachomatis. The load in each sample varied from 10(2) to 10(7) copies ml(-1).

Accuracy of herpes simplex virus detection in liquid-based (SurePath) Papanicolaou tests: a comparison with polymerase chain reaction

A review of our institution's Papanicolaou test records over an 11-yr period showed that liquid-based Papanicolaou tests (LBPTs) had a significantly higher frequency of diagnoses of Herpes simplex virus (HSV)-related cellular changes compared to conventional Papanicolaou smears (77/302,841, 0.026% vs. 56/376,173, 0.015%, P = 0.002). To investigate the accuracy of the diagnosis of HSV by LBPT, we performed conventional polymerase chain reaction (PCR) on the residual samples from 258 prospectively collected LBPT and real-time PCR using a different primer set on a subset of 40 LBPT. Conventional PCR was positive in 22 of 22 cases diagnosed of HSV, 1 of 2 cases diagnosed as suspicious for HSV, and none of 234 LBPT without a cytologic HSV diagnosis. Real-time PCR was positive in 8 of 8 cases diagnosed as HSV and none of the 32 controls. We conclude that LBPT allows an increased detection of HSV that is highly accurate.

Comparison of DNA extraction from cervical cells collected in PreservCyt solution for the amplification of Chlamydia trachomatis

OBJECTIVE

The aim of this study was to compare and evaluate three methods of DNA extraction for the amplification of Chlamydia trachomatis in uterine cervical samples collected in PreservCyt solution. ThinPrep is the trade name for the slide preparation.

METHODS

Thirty-eight samples collected in LCx buffer medium, which were identified as C. trachomatis infected by ligase chain reaction (LCR), were selected for this study. DNA from the PreservCyt samples was extracted by three methods: (i) QIAamp kit, (ii) boiling in Tris-EDTA buffer with Chelex purification, and (iii) Proteinase K digestion with Chelex purification. Sample DNA was tested for the presence of C. trachomatis by PCR using cryptic plasmid research (CTP) primers and major outer membrane protein research momp gene (MOMP) primers. Real-time (LightCycler) PCR for relative C. trachomatis quantification following DNA extraction was performed using primers (Hsp 60) for the 60 kDa heat-shock protein hsp60 gene.

RESULTS

Amplification using CTP primers was the most successful with each of the extraction protocols. Boiling in buffer was the least successful extraction method. QIAamp was the best extraction method, yielding the most positives with both the CTP and MOMP primers. Proteinase K-Chelex extraction gave similar sensitivity to QIAamp extraction with CTP primers but lower for MOMP primers.

CONCLUSIONS

The DNA extraction method must be carefully selected to ensure that larger PCR amplicons can be successfully produced by PCR and to ensure high sensitivity of detection of C. trachomatis. In this study it was found that the QIAamp extraction method followed by PCR with the CTP primers was the most successful for amplification of C. trachomatis DNA.

Liquid based cytology: examination of its potential in a chlamydia screening programme

OBJECTIVE

To assess the feasibility of testing for chlamydia directly on a single liquid based specimen (ThinPrep test) collected for cervical screening.

METHOD

Cervical smears were taken using a Cervex spatula and rinsed in the liquid based cytology collection vial. Following this, the conventional sample for chlamydia testing was taken from the endocervix using an Abbott Collection kit. Cytological specimens were prepared using an automated slide processor. Residual cellular material and the conventional samples were sent to the laboratory where both were tested for chlamydia by ligase chain reaction (LCR). The manufacturer's protocol for LCR urine testing was modified to substitute 1 ml of PreservCyt suspension.

RESULTS

581 women had both swab and cytology suspension tested for Chlamydia trachomatis with LCR. There were 19 concordant positive and 562 concordant negative reports. The stability of chlamydia in the cytology suspension was maintained for at least 5 months.

CONCLUSION

The findings lead us to conclude that samples collected for liquid based cytology using the ThinPrep test collection vial provide a potential platform for chlamydia screening, though the study established several issues to be addressed to make this a practical proposition.

Identification of Bordetella pertussis in a critically ill human immunodeficiency virus-infected patient by direct genotypical analysis of Gram-stained material and discrimination from B. holmesii by using a unique recA gene restriction enzyme site

Bordetella pertussis was diagnosed in a human immunodeficiency virus-infected patient by a newly developed method in which bacterial DNA is amplified directly from sputum Gram-stained slides. The validation of the method is described along with an additional new PCR-based assay that can distinguish between B. pertussis and Bordetella holmesii.

Comparison of methods for detection of Chlamydia trachomatis and Neisseria gonorrhoeae using commercially available nucleic acid amplification tests and a liquid pap smear medium

Annual screening for Chlamydia trachomatis infection is currently recommended for sexually active women 15 to 25 years old and for women older than 25 if they have a new or multiple sex partners and have not used condoms during the previous 3 months. Annual screening for cervical abnormalities using the Pap smear has achieved a substantial reduction in morbidity and mortality from cervical cancer. Screening for Neisseria gonorrhoeae infection has likely contributed significantly to the reduction in the rates of gonococcal infection. The introduction of liquid Pap smear methods using exfoliated cervical cells presents an opportunity to screen for these three conditions using one specimen. We evaluated the preservation of C. trachomatis and Neisseria gonorrhoeae DNAs from ThinPrep liquid media (PreservCyt; Cytyc Corp., Boxborough, Mass.); tested the feasibility of using a clinical specimen of this medium for the detection of cytologic abnormalities, C. trachomatis, and N. gonorrhoeae; evaluated the agreement between ligase chain reaction (LCR) performed on PreservCyt and LCR performed on a cervical specimen; and compared the performance of LCR performed on PreservCyt to those of LCR performed on a cervical specimen, culture, PCR performed on a cervical specimen, on urine, and on a vaginal specimen (a multiple-site infection status standard), and transcription-mediated amplification (for C. trachomatis only) from 255 sexually active adolescent women. The agreement between LCR performed on PreservCyt and LCR from a cervical swab in LCx transport medium was high (for C. trachomatis, agreement = 0.97 and kappa = 0.92; for N. gonorrhoeae, agreement = 0.99 and kappa = 0.96). Test performances were similar for LCR-urine, LCR-cervix, and LCR-ThinPrep, with sensitivities from 93 to 99% for C. trachomatis and 81 to 83% for N. gonorrhoeae and specificities from 95.5 to 99% for C. trachomatis and 99.1 to 99.6% for N. gonorrhoeae using a PCR-based multiple-site infection status standard. This is the first study to examine the agreement between liquid cytologic media and multiple nucleic acid amplification tests for the detection of C. trachomatis and N. gonorrhoeae from patient samples. Cytologic fluid shows promise for simultaneous screening for cytologic abnormalities and sexually transmitted infections.

PreservCyt transport medium used for the ThinPrep Pap test is a suitable medium for detection of Chlamydia trachomatis by the COBAS Amplicor CT/NG test: results of a preliminary study and future implications

The commercial COBAS Amplicor CT/NG test (Roche Diagnostic Systems, Meylan, France) is a sensitive and specific method for detection of Chlamydia trachomatis infections. This test currently consists of using a nucleic acid amplification method to detect C. trachomatis in first-void urine specimens and in endocervical swabs collected in 2-sucrose-phosphate (2SP) transport medium. We conducted a prospective study to determine whether the automated COBAS Amplicor CT/NG test can detect C. trachomatis in cervical specimens collected in PreservCyt transport medium (ThinPrep Pap Test; Cytyc Corporation, Boxborough, Mass.). PreservCyt medium is used to preserve cervical samples before the preparation of ThinPrep slides. We collected 1,000 cervical specimens from young women (age range, 15 to 25 years) during routine Pap smear tests. Only specimens with normal cytology and in which the gynecologist found no clinical evidence of urogenital infections were selected. The samples were stored in PreservCyt transport medium at 15 to 20 degrees C. C. trachomatis was detected in 22 of the 1,000 cervical specimens that had been stored in PreservCyt. To confirm the positive samples, the test was repeated on new endocervical swab specimens collected in 2SP transport medium. Only 9 of the 22 positive patients agreed to undergo this control, but all 9 retested positive. To evaluate the influence of storage conditions on the sensitivity of the C. trachomatis PCR test, all of the positive samples were stored at 15 to 20 degrees C in PreservCyt transport medium and were retested every 2 weeks for 6 weeks. C. trachomatis was successfully amplified from all 22 specimens for the whole 6-week period. The prevalence of C. trachomatis infection was 2.2% in our study population. These results demonstrate that PreservCyt transport medium is a suitable transport medium for detection of C. trachomatis by the COBAS Amplicor CT/NG test. The ThinPrep Pap Test may enable gynecologists to monitor for both cervical lesions and C. trachomatis infections with a single endocervical specimen.

Willingness to pay for new Papanicolaou test technologies

The amount of money a woman is willing to pay for liquid-based cytology technology has not been measured. In the present study, 175 women answered a questionnaire asking how much they would pay to decrease their risk of dying of cervical cancer if a new (liquid-based) Papanicolaou (Pap) test was used in place of the conventional smear. When women assumed that the new Pap test reduced the risk of dying of cervical cancer from 1 in 37,000 to 1 in 50,000, the mean amount they were willing to pay was $237. If women had more than 2 children, they were willing to pay more for the new Pap test than women with 2 or fewer children. These data indicate that liquid-based and conventional Pap tests are undervalued and that cost-effectiveness studies generally have not taken into account the preference of women for new Pap test technologies.

Detection of Chlamydia trachomatis by isothermal ramification amplification method: a feasibility study

Chlamydia trachomatis is the leading cause of sexually transmitted disease in the United States. Effective screening for this agent can facilitate prompt treatment and prevent its sequelae. The recent introduction of liquid-based cytology has made possible the simultaneous screening of cervical intraepithelial lesions and detection of C. trachomatis in a single collection vial. In this study we determined whether cytological fluid could support DNA-based amplification for the detection of C. trachomatis. Three methods were compared, including ramification amplification (RAM), real-time PCR with molecular beacon, and Abbott's ligase chain reaction (LCx). RAM is a novel, recently introduced, isothermal DNA amplification technique that utilizes a circular probe for target detection and achieves exponential amplification through the mechanism of primer extension, strand displacement, and ramification. Our results show that RAM can detect as few as 10 C. trachomatis elementary bodies in less than 2 h, comparable to results with real-time PCR. Thirty clinical specimens collected in PreservCyt solution were tested by LCx, real-time PCR, and RAM. Among 30 specimens, 15 were positive by PCR and LCx and 14 were positive by RAM. One specimen missed by RAM had an inadequate amount of residual cellular material. Our results show that nucleic acid amplification methods can serve to detect C. trachomatis and presumably other sexually transmitted agents in cytological fluid and that the RAM assay can be an alternative to PCR and LCx because of its simplicity and isothermal amplification.