Rapid diagnostic test for ocular adenovirus

A 13-year retrospective review of polymerase chain reaction testing for infectious agents from ocular samples

PURPOSE

Polymerase chain reaction (PCR) is a molecular technique for the diagnosis of ocular infectious disease. In this large patient sample and multiyear study, the impact of PCR for detecting infectious agents from ocular samples was reviewed in comparison with nonmolecular diagnostic techniques.

DESIGN

A retrospective laboratory review of PCR testing.

PARTICIPANTS

Three thousand fifty-six patient samples with a differential of ocular infection.

METHODS

The daily laboratory logs for diagnostic testing were reviewed for PCR, cell culture isolation, shell vial isolation, and Acanthamoeba isolation from January 1997 through May 2010 for herpes simplex virus (HSV), adenovirus, varicella zoster virus (VZV), Chlamydia trachomatis, Acanthamoeba, and infrequent pathogens of intraocular inflammation.

MAIN OUTCOME MEASURES

Incidence of the positive presence of ocular infectious agents.

RESULTS

Polymerase chain reaction results were positive more often than culture results for HSV (P = 0.0001), VZV (P = 0.00001), C. trachomatis (P = 0.00005), and Acanthamoeba (P = 0.04). For adenovirus, cell culture isolation results were positive more often than PCR results (P = 0.001). Polymerase chain reaction was the primary diagnostic test for detecting cytomegalovirus and Toxoplasma.

CONCLUSIONS

The current study demonstrated the importance of PCR as a routine diagnostic test for detecting both common and infrequent ocular pathogens. Cell culture isolation is still a definitive test for adenovirus and a confirmatory test for HSV and Acanthamoeba.

A comparison of methods for detecting adenovirus type 8 keratoconjunctivitis during a nosocomial outbreak in a Neonatal Intensive Care Unit

BACKGROUND

An outbreak of epidemic keratoconjunctivitis (EKC) due to adenovirus (Ad) type 8 and involving 14 members of the hospital staff and 33 neonates admitted to the Neonatal Intensive Care Unit of the local University Hospital occurred between September and December 2000 in Pavia, Italy. The outbreak was preceded by an outbreak of EKC within the community.

OBJECTIVE

To compare the performance of conventional virus isolation on cell cultures, direct detection of Ad antigens in conjunctival cells by a direct fluorescent assay (DFA) and Ad DNA detection in conjunctival swabs by polymerase chain reaction (PCR) for diagnosis of adenoviral conjunctivitis.

STUDY DESIGN

Of conjunctival swabs collected from 47 patients, all were tested by virus isolation, 43 by direct Ad antigen detection, and 37 by Ad DNA detection. Direct Ad antigen detection was carried out by DFA using a group-specific monoclonal antibody. Detection and subgrouping of Ad DNA by nested PCR was performed using two sets of primers complementary to hexon and fiber genes, respectively.

RESULTS

Ad was detected in 24/47 (51.1%), 21/43 (48.8%), and 23/37 (62.1%) samples by virus isolation, direct antigen detection and PCR, respectively. Overall, 30/47 (63.8%) samples were Ad-positive. Of 37 specimens tested in parallel by all three methods, Ad was detected by at least one of the three techniques in 26/37 (70.3%). All Ad isolates were identified as serotype 8 by neutralization, while all PCR-positive samples were identified as belonging to subgroup D. No other virus was isolated from any conjunctival swab. Time required for test completion was 9.6 (4-20) days for virus isolation, 1-2 h for DFA and 24 h for PCR.

CONCLUSIONS

DFA was a sensitive and rapid assay but results depend on the quality of sample and the expertise of the observer. PCR was the most sensitive assay, although it takes longer to perform and requires dedicated facilities; thus, it could be restricted to DFA-negative samples. Virus isolation is still useful from an epidemiological point of view.

Oxybuprocaine induces a false-positive response in immunochromatographic SAS Adeno Test

OBJECTIVE

To investigate whether a solution of oxybuprocaine hydrochloride, 0.4%, results in a false-positive response in an immunochromatographic SAS Adeno Test.

DESIGN

Experimental study.

CONTROLS

Physiologic saline and 2% lidocaine.

TESTING

Each chemical (100 microl) was diluted in a transport medium. Five drops (200 microl) of the resultant solution were dispensed into the round sample well of a test device. Fifteen samples were tested in each group.

MAIN OUTCOME MEASURES

Ten minutes after the start of the test, a colored line in the "specimen" portion of the test membrane was visually read as positive or negative by a masked technician.

RESULTS

No positive reaction was observed in the control groups (physiologic saline and lidocaine). A false-positive reaction was observed in six samples (33.3%) in the oxybuprocaine group. The positive rate was significantly higher in the oxybuprocaine group compared with those in control groups (P = 0.0062, Fisher's extract probability test).

CONCLUSIONS

Oxybuprocaine may induce a false-positive reaction in an immunochromatographic SAS Adeno Test. We recommend the use of lidocaine, instead of oxybuprocaine, for local anesthesia in taking eye swabs from patients with suspected adenovirus infection.

Hemorrhagic viral keratoconjunctivitis in Taiwan caused by adenovirus types 19 and 37: applicability of polymerase chain reaction-restriction fragment length polymorphism in detecting adenovirus genotypes

PURPOSE

Acute keratoconjunctivitis with prominent subconjunctival hemorrhage (SCH) is usually perceived by a clinician as acute hemorrhagic conjunctivitis (AHC) associated with enteroviruses; however, SCH can also be an adenoviruses infection. A rapid and sensitive laboratory diagnosis is helpful for differential diagnosis. Therefore, the sensitivity and applicability of polymerase chain reaction (PCR) and reverse transcription (RT)-PCR diagnoses were evaluated for keratoconjunctivitis associated with viral infection.

METHODS

Conjunctival swabs from patients with acute conjunctivitis were tested using a PCR-restriction fragment length polymorphism (PCR-RFLP) for adenovirus detection and RT-PCR for enterovirus detection. The results were compared with those using the culture isolation and neutralization test; also, the clinical findings of the patients were analyzed with special attention to SCH patterns.

RESULTS

Neither coxsackievirus A type 24 variant (CA24v) nor enterovirus type 70 (EV70) was detected in 113 patients with acute conjunctivitis. The positive results of adenovirus (Ad) were 39.9% by the PCR method and 37.1% by culture isolation. For the patients with adenoviral conjunctivitis, 68.1% was owing to Ad37 and 19.2% was owing to Ad19. SCH was present in 51.5% of the positive cases, and 44.7% of the Ad-positive patients had secondary illnesses.

CONCLUSIONS

SCH can be a predominant presentation of Ad19 and Ad37 keratoconjunctivitis and may herald a new stage in the evolution of adenoviruses. PCR and PCR-RFLP are rapid and reliable methods for Ad detection and typing; however, if the amplified genes and restriction enzymes are not properly selected, they may not be able to detect new genotypes of adenoviruses or the evolution of these viruses.

Evaluation of the shell vial technique for detection of ocular adenovirus. Community Ophthalmologists of Pittsburgh, Pennsylvania

PURPOSE

The shell vial technique is a cell culture method that uses centrifugation and immunofluorescence to decrease the time required for a positive test. The authors evaluated the shell vial technique as a diagnostic test to detect adenovirus in conjunctival specimens of patients with adenoviral conjunctivitis.

DESIGN

Retrospective and prospective case series.

PARTICIPANTS

Forty-six patients with adenoviral culture-positive ocular infection.

METHODS

The minimum time of incubation (days) that was required for testing clinical isolates with the shell vial was determined with adenovirus serotypes 5 and 8. In a masked retrospective study, 25 true-positive (frozen clinical samples) and 25 true-negative specimens were tested for the presence of adenovirus using the shell vial technique. The 25 true-negative samples included herpes simplex virus, Chlamydia trachomatis, Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. In a prospective study, 21 patients who later tested positive in cell culture for adenovirus were concurrently tested with shell vial.

MAIN OUTCOME MEASURES

The time of incubation was determined in days, and the sensitivity, specificity, positive and negative predictive values, and the efficacy of the shell vial test were determined.

RESULTS

The minimal time of incubation for testing ocular samples by shell vial was 3 days. In the retrospective study, the sensitivity, specificity, positive predictive value, negative predictive value, and efficacy were 92%, 100%, 100%, 93%, and 96%, respectively. Comparably (P = 0.99), in the prospective study the sensitivity, specificity, positive predictive value, negative predictive value, and efficacy were 95%, 100%, 100%, 96%, and 97%, respectively. The shell vial (93%, 43 of 46) was equivalent (P = 0.42) to cell culture (100%, 46 of 46) for detecting adenovirus, but a positive result was obtained in significantly less time (3 days versus 9.41 +/- 6.23 days) (P = 0.00001).

CONCLUSIONS

The shell vial technique was found to be a definitive method for identifying adenovirus from ocular specimens. A clear benefit for the ophthalmologist is that the test can provide a faster positive result (3 days) compared with conventional cell culture, which can take 1 to 3 weeks for adenovirus isolation.

Improved impression cytology techniques for the immunopathological diagnosis of superficial viral infections

BACKGROUND

For epidemiological and therapeutic reasons early diagnosis of superficial viral infections is crucial. Conventional microbiological techniques are expensive, time consuming, and not sufficiently sensitive. In this study impression cytology techniques were evaluated to analyse their diagnostic potential in viral infections of the ocular surface.

METHOD

A Biopore membrane device instead of the original impression cytology technique was used to allow better quality and handling of the specimens. The impressions were processed, using monoclonal antibodies and immunoperoxidase or immunofluorescence techniques to assess the presence of herpes simplex virus, varicella zoster virus, or adenovirus antigens. Ocular surface specimens from healthy individuals (n = 10) and from patients with suspected viral surface disease (n = 19) were studied. Infected and non-infected cell cultures served as controls.

RESULTS

This modified technique of impression cytology allowed the collection of large conjunctival and corneal epithelial cell layers with excellent morphology. Immunocytological staining of these samples provided diagnostic results for all three viruses in patients with viral surface disease.

CONCLUSIONS

The use of Biopore membrane devices for the collection of ocular surface epithelia offers new diagnostic possibilities for external eye diseases. Immunopathological methods that are applied directly on these membrane devices can provide virological results within 1-4 hours. This contributes considerably to the clinical management of patients with infectious diseases of the ocular surface.

Rapid diagnosis of adenoviral conjunctivitis on conjunctival swabs by 10-minute immunochromatography

PURPOSE

Several methods are available for the diagnosis of acute conjunctivitis, all of which are time-consuming or require the use of a well-equipped laboratory. A new method, immunochromatography (IC), for detecting the presence of adenovirus (Ad) has been developed. Two direct rapid tests to detect Ad antigen, IC and enzyme immunoassay (EIA), were compared with regard to sensitivity, specificity, and technical complexity.

METHODS

The study materials consisted of 130 swabs from patients with conjunctivitis (95 samples of adenoviral conjunctivitis proven by positive virus DNA on polymerase chain reaction [PCR], 35 samples of nonadenoviral conjunctivitis proven by PCR). IC is a one-step procedure that detects the presence of adenoviral antigen by sandwich EIA on a paper disc.

RESULTS

In 95 adenoviral DNA-positive samples by PCR, the sensitivity and specificity of IC were 54.7% and 97.1%, respectively, whereas those of EIA were 50.5% and 100%, respectively. By IC, PCR-positive Ad type 3 was recognized in 31%; Ad4 in 100%; Ad7 in 60%; Ad8 in 67%; and Ad37 in 59%, showing similar positivity rates for different serotypes (except Ad7) to those using EIA. Visual determination of the presence of Ad took an average of 10 minutes by IC compared with 70 minutes by EIA.

CONCLUSIONS

These results indicate that IC is a more rapid and easier test compared with EIA, and it has high specificity. Detection of Ad antigen by this simple and rapid method will serve physicians as a useful tool for early diagnosis and prevention of adenoviral conjunctivitis.

Prospective study of adenovirus antigen detection in eye swabs by radioimmune dot-blot

Rapid laboratory diagnosis of ocular adenovirus infection is crucial in the containment of nosocomial transmission of the virus. In a large prospective study of adenovirus assay in eye swabs, antigen detection by radioimmune dot-blot (turnaround time 72 hours) achieved a sensitivity of 67% (239/355) and a specificity of 93% (3065/3285) in comparison with virus culture (median turnaround time 14 days). When specimens weakly reactive for adenovirus antigen, or equally reactive for both adenovirus antigen and Chlamydia trachomatis antigen, were considered falsely reactive in the adenovirus test, the sensitivity of the latter was reduced and false positive reactions were only marginally less frequent. The radioimmune dot-blot provides a more rapid diagnosis of ocular adenovirus infection than virus culture, but the high risk of false negative and in particular false positive results limits its clinical utility.

An immune dot-blot technique for the diagnosis of ocular adenovirus infection

The development of a monoclonal antibody based radio-immune dot-blot technique (IDBT) for the rapid detection of adenovirus is described. 718 conjunctival swabs from patients with acute keratoconjunctivitis were examined by conventional cell culture isolation techniques and IDBT. IDBT identified adenovirus in 64 of 75 culture positive samples and also in a further 34 culture negative samples [Sensitivity (IDBT versus culture) 85.3%; Specificity 92.2%]. IDBT is considered to be a simple, clinically relevant, technique for the rapid identification of adenovirus infection of the eye.

Evaluation of immunologic tests for the detection of ocular herpes simplex virus

Four immunologic tests, Herpchek (HC), latex agglutination (AGG), enzyme immunofiltration (IF), and 1 hour enzyme-linked immunoassay (1EIA), were evaluated for detecting herpes simplex virus (HSV) from ocular specimens. Compared with the standard of HSV-positive cell cultures, 24 (65%) of 37 positive HC tests and 22 (59%) of 37 positive IF tests were significantly more sensitive (P less than 0.0005) than the AGG (3%, 1/37) and 1EIA (26%, 1/34) tests. The HC and IF tests were 100% specific, and easy to interpret. In addition, the clinical diagnosis of HSV infection after a thorough ophthalmologic examination was as sensitive (59%, 22/37) (P = 0.4) as any of the immunologic tests. In conclusion, for definitive diagnosis of HSV, the HC test seems more suitable for a central laboratory that handles a large number of viral specimens, and processes HC-negative tests with follow-up cell culture isolation. The enzyme immunofiltration test seems more suitable for a low-volume viral laboratory which confirms all IF test samples with follow-up cell culture isolation.

Epidemiology and diagnosis of acute conjunctivitis at an inner-city hospital

Chlamydia has been found to be the cause of a high percentage of cases of neonatal and chronic conjunctivitis in an inner-city population. To assess the etiology and epidemiology of acute conjunctivitis in this population, conjunctival scrapings were sampled from 45 patients presenting to an ocular emergency room; and replicate chlamydial, viral, and bacterial cultures and cytology tests were done. No cases of chlamydial conjunctivitis were diagnosed, although a viral etiology was established in 36% of the cases and a bacterial etiology in 40%. Twenty-four percent of the cases were not diagnosed. The authors recommend limiting the initial laboratory workup of patients with acute conjunctivitis to obtaining conjunctival smears for Gram and Giemsa staining. Chlamydial direct immunofluorescent monoclonal antibody (DFA) should be done if the patient is sexually active. Hyperacute conjunctivitis or acute conjunctivitis refractory to treatment mandates a more complete set of laboratory tests.

Comparison of direct rapid tests for the detection of adenovirus antigen in routine conjunctival specimens

Two direct rapid tests to detect adenovirus antigen, enzyme immunoassay (EIA) and immunofiltration (IF) were compared with regard to sensitivity, specificity, ease of interpretation, and technical complexity against 75 adenovirus culture-positive and 35 adenovirus culture-negative conjunctival swab specimens. Enzyme immunoassay and IF were equally sensitive (P = 0.5), with sensitivities of 80.6 and 79.0%, respectively, when swab specimens were collected from patients within 7 days of the onset of clinical symptoms of adenovirus infection. After 7 days of clinical onset, IF (46.2%) was more sensitive (P less than 0.01) than EIA (0.0%), and was able to detect residual antigen in three culture-negative specimens. Enzyme immunoassay and IF were equally specific (100%). Both tests were easy to interpret, but IF was more technically complex and is not yet commercially packaged. Enzyme immunoassay could benefit either an office practice or a central laboratory, whereas IF is better suited for the latter.