Relative Light Units Values Research Articles

Semi-quantitative HPV viral load in patients with ASC-US cytology: viral load correlates strongly with the presence of CIN but only weakly with its severity.

This study was performed to evaluate the prognostic significance of human papillomavirus (HPV) viral load, expressed in relative light units (RLUs), in patients with atypical squamous cells of undetermined significance (ASC-US) cytology. A total of 349 ASC-US cases with HPV infection, detected using Hybrid Capture 2, were diagnosed histologically. A colposcopically directed punch biopsy was performed on acetowhite areas. Endocervical curettage biopsy and random cervical punch biopsy in four quadrants were performed in unsatisfactory colposcopy cases. In negative colposcopy cases, random cervical punch biopsy in four quadrants was performed. Case with no cervical intraepithelial neoplasia (CIN), CIN1 and CIN2+ (CIN2/CIN3) accounted for 162, 135 and 52 cases, respectively. The mean age showed no difference among the three groups (P=0.510). There was a significant correlation between RLU values and the presence of CIN (P<0.001), but less so with its severity: the median RLU values for negative, CIN1 and CIN2+ cases were 42.68, 146.45 and 156.43, respectively, with widely overlapping confidence intervals. The cut-off values of RLU to detect CIN1+ and CIN2+ were 6.73 and 45.64, respectively. The HPV viral load in ASC-US cases showed a significant correlation with the presence of CIN and less so with its severity, and showed large overlap of viral loads between grades of CIN. In ASC-US cases, RLU was not an accurate predictor of immediate high-grade CIN.

Interlaboratory Reproducibility and Proficiency Testing within the Human Papillomavirus Cervical Cancer Screening Program in Catalonia, Spain

In Catalonia, a screening protocol for cervical cancer, including human papillomavirus (HPV) DNA testing using the Digene Hybrid Capture 2 (HC2) assay, was implemented in 2006. In order to monitor interlaboratory reproducibility, a proficiency testing (PT) survey of the HPV samples was launched in 2008. The aim of this study was to explore the repeatability of the HC2 assay's performance. Participating laboratories provided 20 samples annually, 5 randomly chosen samples from each of the following relative light unit (RLU) intervals: <0.5, 0.5 to 0.99, 1 to 9.99, and ≥10. Kappa statistics were used to determine the agreement levels between the original and the PT readings. The nature and origin of the discrepant results were calculated by bootstrapping. A total of 946 specimens were retested. The kappa values were 0.91 for positive/negative categorical classification and 0.79 for the four RLU intervals studied. Sample retesting yielded systematically lower RLU values than the original test (P<0.005), independently of the time elapsed between the two determinations (median, 53 days), possibly due to freeze-thaw cycles. The probability for a sample to show clinically discrepant results upon retesting was a function of the RLU value; samples with RLU values in the 0.5 to 5 interval showed 10.80% probability to yield discrepant results (95% confidence interval [CI], 7.86 to 14.33) compared to 0.85% probability for samples outside this interval (95% CI, 0.17 to 1.69). Globally, the HC2 assay shows high interlaboratory concordance. We have identified differential confidence thresholds and suggested the guidelines for interlaboratory PT in the future, as analytical quality assessment of HPV DNA detection remains a central component of the screening program for cervical cancer prevention.

Interpolation function estimates post mortem interval under ambient temperature correlating with blood ATP level

ObjectiveWe developed a mathematical model using interpolation function, to characterize the correlation between blood ATP levels in the right ventricle of rabbit and post mortem interval (PMI) at different ambient temperatures. MethodsForty-eight healthy rabbits were randomly divided into 6 groups of 8 each. The sacrificed rabbits were maintained in calorstats at 10°C, 15°C, 20°C, 25°C, 30°C and 35°C, respectively. Blood from the right ventricle was sampled every 4h until 72h after death. At different time points, ATP concentrations in the blood samples were measured using an ATP fluorescence rapid detector, and then displayed on the detector screen in the form of relative light units (RLU). Relationship between PMI and ATP degradation levels was investigated statistically by SPSS 17.0 and MATLAB 10.0 software. ResultsWe obtained six regression equations (Ra2=0.887–0.929) with RLU values at PMIs of 72h (10°C), 60h (15°C), 56h (20°C), 52h (25°C), 40h (30°C) and 32h (35°C), and an interpolation function (Ra2=0.930) was established with PMI as the dependent variable (z), RLU value as independent variable (x) and temperature as independent variable (y). ConclusionInterpolation function is an appropriate choice for PMI estimation by weakening influence of ambient temperature.

Best practices in disinfection of noncritical surfaces in the health care setting: Creating a bundle for success

Because increasing evidence suggests that the environment plays a role in transmission of health care-associated infections, more attention is focusing on environmental cleaning and improving its efficacy. Creating and sustaining a successful cleaning and disinfection program should include several key components using a bundle approach and requires ongoing commitment within the institution.

A study of three methods for assessment of hospital environmental cleaning

Abstract Background The environment is increasingly appreciated as a factor in healthcare associated infections. Several methods for measuring environmental contamination are available. Our goal was to compare quantitative microbiology to adenosine triphosphate (ATP) detection on a sample of hospital surfaces both pre- and post-cleaning, and to assess fluorescent marker results in the same rooms. Methods In a sample of 10 rooms, ATP readings by relative light units (RLU) and quantitative determination of colony forming units (CFU) were measured pre- and post-cleaning on 10 high-touch hospital environmental surfaces. Removal of fluorescent markers (FM) was evaluated post-cleaning in the same rooms. Methods were compared using correlational analyses. Results The ATP readings were usually higher than CFU readings compared with their respective norms for cleanliness. The direction of change in cleanliness assessment (usually down after cleaning) was consistent between the RLU and CFU methods. In addition, CFU and RLU values correlated pre-cleaning, but not postcleaning. Areceiver operating characteristic (ROC) curve suggested a ‘clean' cutoff of 8 RLU/cm 2 for the ATP assay, higher than 2.5 RLU/cm 2 cutoff most often used. Neither method correlated well with FM results. Conclusions The methods for measuring environmental cleanliness have shown inconsistent correlation, but measure different parameters. Additional studies are needed to assess the correlation and predictive value of the three methods for room cleanliness assessment.

Glycophenotype Evaluation in Cutaneous Tumors Using Lectins Labeled with Acridinium Ester

Background. Tumor cells show alterations in their glycosylation patterns when compared to normal cells. Lectins can be used to evaluate these glycocode changes. Chemiluminescence assay is an effective technique for quantitative analysis of proteins, nucleic acids, and carbohydrates due to its high sensitivity, specificity, and rapid testing. Objective. To use histochemiluminescence based on lectin conjugated to acridinium ester (AE) for the investigation of glycophenotype changes in cutaneous tumors. Methods. Concanavalin A (Con A), Peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), and Maackia amurensis agglutinin (MAA) were conjugated to acridinium ester. Biopsies of cutaneous tumors and normal skin were incubated with the lectins-AE, and chemiluminescence was quantified and expressed as Relative Light Units (RLU). Results. Actinic keratosis (AK), keratoacanthoma (KA), squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) showed lower expression of α-D-glucose/mannose and α-L-fucose residues compared to normal tissue. Cutaneous tumors displayed higher expression of Gal-β(1-3)-GalNAc residues than normal tissue. AK and SCC exhibited higher expression of Neu5Ac-α(2,3)Gal residues than normal epidermis. KA and BCC showed equivalent RLU values compared to normal tissue. Conclusions. Lectin histochemiluminescence allowed quantitative assessment of the carbohydrate expression in cutaneous tissues, contributing to eliminate the subjectivity of conventional techniques used in the histopathological diagnosis.

Development and preliminary validation of an antibody filtration-assisted single-dilution chemiluminometric immunoassay for potency testing of Piscirickettsia salmonis vaccines

Challenge with live pathogens could be substituted by serology for many veterinary diseases, however little progress has been made in the development of alternative batch vaccine potency tests for fish. This study reports the development and preliminary validation of a single-dilution filtration-assisted chemiluminometric immunoassay (SD FAL-ELISA) applied to measure anti Piscirickettsia salmonis IgM in individual or pooled serum and mucus samples. The assay was set up to test a single-dilution of the sample. Serum SD FAL-ELISA yielded a sensitivity of 90% and a specificity of 96%. SD FAL-ELISA was applied to evaluate pooled and individual samples from P. salmonis challenge assessments. Relative-light units values (RLU) obtained by SD FAL-ELISA were proportional to antibody levels in serum. RLU values obtained from pooled and individual serum samples increased with the observed relative percent survival (RPS) values, indicating a correlation between protection and specific IgM levels. Results obtained for specific IgM in mucus samples was not related to the RPS, but discriminated the vaccine that yielded high RPS (86.4%) from the others (40.9 and 54.5%). This is the first report on the development of an indirect high-throughput serological assessment for P. salmonis vaccine potency testing using both pooled or individual serum and cutaneous mucus samples.

Optimization and proficiency testing of a pseudovirus-based assay for detection of HIV-1 neutralizing antibody in China

Among the neutralizing antibody evaluation assays, the single-cycle pseudovirus infection assay is high-throughput and can provide rapid, sensitive and reproducible measurements after a single cycle of infection. Cell counts, pseudovirus inoculation levels, amount of diethylaminoethyl-dextran (DEAE-dextran), and the nonspecific effects of serum and plasma were tested to identify the optimal conditions for a neutralizing antibody assay based on pseudoviruses. Optimal conditions for cell counts, pseudovirus inoculation, and amount of DEAE-dextran were 1 × 10(4)cells/well, 200TCID(50)/well, and 15 μg/ml, respectively. Compared with serum samples, high-concentration anticoagulants reduced the relative light unit (RLU) value. The RLU value increased sharply initially but then decreased slowly with dilution of the plasma sample. Test kits containing 10 HIV-1 CRF07/08_BC pseudovirus strains and 10 plasma samples from individuals infected with HIV-1 CRF07/08_BC were assembled into two packages and distributed to nine laboratories with a standard operating procedure included. For the 10 laboratories that evaluated the test, 17 of 44 (37%) laboratory pairs were considered equivalent. A statistical qualification rule was developed based on the testing results from 5 experienced laboratories, where a laboratory qualified if at least 83% of values lied within the acceptable range.

Human papillomavirus viral load expressed as relative light units (RLU) correlates with the presence and grade of preneoplastic lesions of the uterine cervix in atypical squamous cells of undetermined significance (ASCUS) cytology

Human papillomavirus (HPV) testing is more sensitive and has higher negative predictive value (NPV) than the Pap test for the detection of cervical intraepithelial neoplasia (CIN) in patients with atypical squamous cells of undetermined significance (ASCUS) cytology, but has low specificity, leading to high referral rates to second-level triage. Our goal was to identify the prognostic significance of HPV viral load figures. We evaluated whether a correlation between viral load, expressed as relative light units/cutoff (RLU/CO), and the severity of cervical lesions existed in 614 ASCUS cases. Hybrid Capture 2 (HC2®) RLU/CO values, categorised into five classes, were correlated to clinical outcomes and statistically analysed. A significant correlation (p < 0.0001) was observed between increasing RLU values and the prevalence of high-grade CIN (CIN2/CIN3). The mean RLU values for negative, low-grade and high-grade lesions were 68.1, 172.5 and 1,020.0 RLU/CO, respectively (p < 0.0001). CIN2/CIN3 ranged from 4% for 0 < RLU/CO values ≤ 1, to 5% for 1 < RLU/CO values ≤ 10, to 9% for 10 < RLU/CO values ≤ 100, to 23% for 100 < RLU/CO values ≤ 1,000 and to 48% when RLU/CO values were >1,000 (p < 0.05). The HPV viral load in ASCUS cases significantly correlates with the severity of cervical cancer precursors. These data may have prognostic value, as they significantly correlate with the probability of a CIN2+ .

Three-Year History of Transcription-Mediated Amplification-Based Trichomonas vaginalis Analyte-Specific Reagent Testing in a Subacute Care Patient Population

A total of 7,899 specimens submitted for live clinical Trichomonas vaginalis analyte-specific reagent (ASR) screening from 2008 to 2010 were audited on the basis of patient gender, specimen source, molecular Neisseria gonorrhoeae and Chlamydia trachomatis results, and relative light unit (RLU) data yielded by T. vaginalis ASR. Only 1.4% of the screening was ordered by emergency department clinicians. The screening volume in 2010 was 126% higher than that in 2008. The proportions of annual female and male screening remained consistent throughout the 3-year interval (∼92 and 8%, respectively). Although 71.8 and 9.5% of screening was performed on endocervical and vaginal specimens, respectively, over the 3-year period, no significant difference was noted in the T. vaginalis detection rates (8.9 and 8.6%, P = 0.85). Increased T. vaginalis detection was derived from female urine specimens (12.6%) compared to female genital swabs (P = 0.0004). The proportion of female urine screening increased during the 3-year interval (P < 0.0002). T. vaginalis detection rate in males was 6.6%, with no difference between urethral and urine T. vaginalis detection (P = 0.53). The mean RLU value for 714 positive specimens was 3,971,441; analogous values for each female specimen source and combined male source testing showed no variance (P ≥ 0.29). Combined-gender T. vaginalis detection rate (9.1%) was significantly greater than those of C. trachomatis (5.9%) and N. gonorrhoeae (1.5%; P < 0.0002). Equivocal results presented at a rate of 0.4%. T. vaginalis ASR is an increasingly utilized assay that yields higher detection rates than other sexually transmitted infection etiologies in this community subacute care setting.

Transcription Factor Rational Design Improves Directed Differentiation of Human Mesenchymal Stem Cells Into Skeletal Myocytes

There is great interest in transdifferentiating cells from one lineage into those of another and in dedifferentiating mature cells back into a stem/progenitor cell state by deploying naturally occurring transcription factors (TFs). Often, however, steering cellular differentiation pathways in a predictable and efficient manner remains challenging. Here, we investigated the principle of combining domains from different lineage-specific TFs to improve directed cellular differentiation. As proof-of-concept, we engineered the whole-human TF MyoDCD, which has the NH(2)-terminal transcription activation domain (TAD) and adjacent DNA-binding motif of MyoD COOH-terminally fused to the TAD of myocardin (MyoCD). We found via reporter gene and marker protein assays as well as by a cell fusion readout system that, targeting the TAD of MyoCD to genes normally responsive to the skeletal muscle-specific TF MyoD enforces more robust myogenic reprogramming of nonmuscle cells than that achieved by the parental, prototypic master TF, MyoD. Human mesenchymal stem cells (hMSCs) transduced with a codon-optimized microdystrophin gene linked to a synthetic striated muscle-specific promoter and/or with MyoD or MyoDCD were evaluated for complementing the genetic defect in Duchenne muscular dystrophy (DMD) myocytes through heterotypic cell fusion. Cotransduction of hMSCs with MyoDCD and microdystrophin led to chimeric myotubes containing the highest dystrophin levels.

P3-S1.11 Per cent additional test positive following positive Combo 2 Chlamydia (CT) and gonorrhoea (GC) specimens: assessing the impact of prevalence

BackgroundThe positive predictive value (PPV) of a screening test (ST) is a function of prevalence and ST specificity and is expected to decrease with decreasing prevalence unless ST specificity approaches...

Clinical, colposcopic and pathological characteristics of cervical and vaginal high-grade lesions negative for HPV by Hybrid Capture 2

Objective Less than 5% of women with cervical or vaginal biopsy proven high-grade squamous intraepithelial lesions (HG-SIL) show a negative Hybrid Capture 2 (HC2) result. We analyzed 1) human papillomavirus (HPV) genotypes by PCR in order to determine whether these cases represent infections by common or unusual types, and 2) the clinical, colposcopic and pathological differential characteristics of these patients. Methods 646 women with a histological diagnosis of HG-SIL and a HC2 test collected within 6 months prior to the diagnosis were identified. Patients with a negative HC2 result were selected. HPV was typed in the biopsy specimen in all by PCR using SPF10 and GP5+/6+ primers, and p16 INK4a immunostaining was performed. The clinical and colposcopy findings of these women were compared with a control group of HG-SIL with positive HC2 result. Results 20 women (3.1%) with HG-SIL had a negative HC2. All biopsies were positive for p16 INK4. PCR analysis detected HPV types included in HC2 test in 55% of the cases, with an identical percentage of common viruses between women with relative light unit values above or below 0.40 (p = .361). False negative HC2 tests increased with age (p = .002) and were more frequent in patients with non satisfactory colposcopy or small sized lesions (p < .001). Conclusion A negative HC2 test is an infrequent event in women with HG-SIL. Common HPV types are identified in over half of the cases. Older women and patients with small lesions or non satisfactory colposcopy have a higher rate of HC2 negative results.

The use of adenosine triphosphate bioluminescence to assess the efficacy of a modified cleaning program implemented within an intensive care setting

A total environmental cleaning system based on microfiber technology was implemented within 2 intensive care units (ICUs). The efficacy of this modified cleaning program was assessed using adenosine triphosphate (ATP) bioluminescence. A team of trained hygiene technicians cleaned all near-patient furniture and equipment twice a day using ultramicrofiber cloths. Every week for 40 weeks, 10 surfaces within a randomly selected bed area were sampled using the 3M Clean-Trace Clinical Hygiene Monitoring System (3M Health Care Ltd, Loughborough, United Kingdom). The ability of the modified cleaning program to reduce surface contamination to "acceptable" levels was measured against previously proposed benchmark ATP values. In comparison with normal cleaning procedures routinely carried out by the nurses, the modified cleaning program significantly reduced (P < .001) the ATP readings obtained from surfaces within the near-patient environment. In both ICUs, 95% of surfaces sampled after modified cleaning had relative light unit values of <500 and were deemed "clean." Almost 90% of the surfaces could also be "passed" using the more stringent benchmark value of 250 relative light units. However, regardless of benchmark value used, the majority of surfaces sampled could also be considered adequately clean prior to them being cleaned by the hygiene technicians. The use of ATP bioluminescence has been proposed as a means to improve the management of hospital cleaning. Use of benchmark values can help continually monitor the efficacy of existing cleaning programs. However, when evaluating novel or new cleaning practices, baseline cleanliness (ie, the level of cleanliness routinely achieved using normal cleaning procedures) must also be taken into consideration, or the efficacy of modified cleaning will be overestimated.

Floor cleaning: effect on bacteria and organic materials in hospital rooms

Routine surface cleaning is recommended to control the spread of pathogens in hospital environments. In Norway, ordinary cleaning of patient rooms is traditionally performed with soap and water. In this study, four floor-mopping methods--dry, spray, moist and wet mopping--were compared by two systems using adenosine triphosphate (ATP) bioluminescence (Hygiena and Biotrace). These systems assess residual organic soil on surfaces. The floor-mopping methods were also assessed by microbiological samples from the floor and air, before and after cleaning. All methods reduced organic material on the floors but wet and moist mopping seemed to be the most effective (P < 0.001, P < 0.011, respectively, ATP Hygiena). The two ATP methods were easy to use, although each had their own reading scales. Cleaning reduced organic material to 5-36% of the level present before cleaning, depending upon mopping method. All four mopping methods reduced bacteria on the floor from about 60-100 to 30-60 colony-forming units (cfu)/20cm2 floor. Wet, moist and dry mopping seemed to be more effective in reducing bacteria on the floor, than the spray mopping (P=0.007, P=0.002 and P=0.011, respectively). The burden of bacteria in air increased for all methods just after mopping. The overall best cleaning methods seemed to be moist and wet mopping.

Detection of human papillomavirus in pterygium and conjunctival papilloma by hybrid capture II and PCR assays

To elucidate the putative role of human papillomavirus (HPV) infection in pterygium and conjunctival papilloma. Hybrid capture II (HC-II) and polymerase chain reaction (PCR) assays were performed to detect HPV in pterygium (42 samples obtained from 40 patients) and conjunctival papilloma (8 samples from 6 patients). The amount of HPV DNA was evaluated by measurement of relative light units (RLUs) on a luminometer. All papilloma samples were positive for HPV DNA by PCR and HC-II. The RLU values for specimens of recurrent and re-recurrent papilloma were markedly higher than those for specimens of primary lesions. HPV was detected by PCR in 2 of 42 (4.8%) beta-globin-positive pterygium specimens, whereas HC-II showed that HPV was negative in all pterygium samples. Our results support the hypothesis that HPV DNA is associated with the pathogenesis of conjunctival papilloma, but not pterygium. RLU measurement by HC-II may serve as a marker for evaluating the activity of HPV in conjunctival tumours.

Anal Human Papillomavirus Testing with Digene's Hybrid Capture 2 Using Two Different Sampling Methods

The incidence of human papillomavirus detection in the anal canal is rising. Efficient anal screening by cytology is hampered because of poor specificity. Human papillomavirus (HPV) testing is proposed in addition to Papanicolaou (Pap) testing for the detection of cervical neoplasia. The purpose of this study was to determine the usefulness of a human papillomavirus-DNA detection test to detect human papillomavirus-associated disease and to compare two different methods of sample collection. In 555 patients, anal samples were obtained by using a cervical brush and a Dacron swab to test for high-risk and low-risk human papillomavirus-DNA. Patients positive for human papillomavirus-DNA underwent anoscopy. Biopsies were taken from visible lesions. Low-risk human papillomavirus-DNA was found in 325 of 555 patients (58.6 percent) and high-risk human papillomavirus-DNA in 285 of 555 patients (51.4 percent). Positive results confined to one single test method were higher for Dacron swab sampling (2.3 vs. 4.3 percent for low-risk human papillomavirus, P < 0.0001; 3.1 vs. 4.9 percent for high-risk human papillomavirus, P < 0.001). A positive correlation of relative light units was found for both sampling methods in the total cohort (P < 0.0001) as well as for patients who tested human papillomavirus-positive by both sampling techniques (P < 0.0001). Sampling with Dacron swabs yielded higher relative light units values compared with sampling with cervical brush for low-risk human papillomavirus-DNA and high-risk human papillomavirus-DNA. Anal screening for human papillomavirus-DNA by hybrid capture 2 is a useful method for detection of human papillomavirus-associated disease. Sample collection using Dacron swabs identifies more human papillomavirus-positive patients, and yields higher relative light unit values than using the cervical brush. Further studies are needed to determine the exact value of hybrid capture 2 in the screening for (pre)cancerous lesions of the anal canal.

Optimization of Vibrio harveyi Luminometry Assay for Detecting Quorum Sensing Inhibitors

The luminometry assay using the wild-type Vibrio harveyi BB120 was evaluated as a possible detection method for quorum sensing inhibitors. The effects of the concentration of the quorum sensing signal molecule (AHL) as well as the cell density of the reporter strain and the different AHL analogues on luminescence expressed as relative light units (RLU) were examined. Inhibition of V. harveyi luminescence was observed in a dose dependent manner for all five AHL analogues. The RLU values exhibited linearity within the range of 2.9 x 102 ~ 3.2 x 105. Detection up to 102nM was possible for dodecanoyl-homoserine lactone and AHLs with alkyl chain lengths of C-8~C-14 were more active than the shorter chain-lengthed hexanoyl-homoserine lactones. Lipophilicity of the AHL seems to affect the sensitivity of the assay.

The borderline or weakly positive Hybrid Capture II HPV test: A statistical and comparative (PCR) analysis

Objectives Recent studies have hypothesized that laboratory contamination may influence interpretation of Hybrid Capture II (HCII) human papillomavirus (HPV) detection assay values. Study design To test this hypothesis, 572 consecutive HCII samples were statistically evaluated to test the null hypothesis that cross-well contamination was not present. In addition, 874 consecutive paired samples from patients followed by both HCII and polymerase chain reaction (PCR) analysis were compared. Results A Kendall's tau measure of association among adjacent wells yielded a P value of .016, rejecting the null hypothesis of no contamination. Analysis of relative light unit values between 0.8 and 1.5 rejected the null hypothesis at P = .077. Moreover, PCR positivity was significantly higher for samples with HCII values above 1.5 vs 0.8 to 1.5 ( P = .001). Conclusion Cross-well contamination of samples occurs during processing, and may influence interpretation of some borderline positives. The proportion of cases at risk is low (<3%). Nevertheless, this information may be germane to the interpretation and reporting of marginally positive HCII test values.

Efficiency of the Hybrid Capture 2 HPV DNA Test in Cervical Cancer Screening

The aim of this study was to determine the efficiency of the Hybrid Capture 2 (HC2; Digene, Gaithersburg, MD) human papillomavirus (HPV) assay for the detection of cervical neoplasia. Of the 1,785 patients recruited, 462 (25.88%) were referred for colposcopy owing to previously detected cytologic abnormalities, and 1,323 (74.12%) were voluntary candidates for screening. For all patients, a Papanicolaou smear and a monolayer smear (ThinPrep, Cytyc, Boxborough, MA) were done. HPV DNA was detected on the residual liquid-based material. False-positive results were observed in 111 cases and comprised 34 cross-reactions (1.90%) and 77 false-positive cases (4.31%) owing to a contiguous strong chemiluminescence signal. Interestingly, all these samples had a relative light units value of 1 to 3 and were contiguous to a sample with a very high HPV DNA load. The final results showed that high-risk and low-risk HPV DNA were detected in 480 samples (26.89%) and 135 samples (7.56%), respectively. Although HC2 can be considered a reliable and sensitive test for HPV DNA detection, we do not advocate its use for large-scale screening for cervical neoplasia.