Clinical Usefulness of Multiplex PCR Lateral Flow in MRSA Detection: A Novel, Rapid Genetic Testing Method

Methicillin-resistant Staphylococcus aureus (MRSA) with exogenous cassette DNA containing the methicillin-resistant gene mecA (SCCmec) poses a problem as a drug-resistant bacterium responsible for hospital- and community-acquired infections. The frequency of MRSA detection has recently been increasing rapidly in Japan, and SCCmec has also been classified more diversely into types I–V. A rapid test is essential for early diagnosis and treatment of MRSA infections, but detection by conventional methods requires at least two days. The newly developed multiplex PCR lateral flow method allows specific amplification of femA to detect S. aureus, mecA to detect SCCmec, and kdpC to detect SCCmec type II; moreover, PCR products can be evaluated visually in about 3 h. In the present study, we developed a PCR lateral flow method for MRSA using this method and investigated its clinical usefulness in the detection of MRSA. The results showed a diagnostic concordance rate of 91.7% for MRSA and methicillin-susceptible S. aureus between bacteriological examination and PCR lateral flow, and a high level of specificity in PCR lateral flow. In addition, a higher detection rate for S. aureus using the same sample was observed for PCR lateral flow (70.2%) than for bacteriological tests (48.6%). The above results show that PCR lateral flow for MRSA detection has high sensitivity, specificity, and speed, and its clinical application as a method for early diagnosis of MRSA infections appears to be feasible

Discrimination of Antibody to Herpes B Virus from Antibody to Herpes Simplex Virus Types 1 and 2 in Human and Macaque Sera▿

The antigenic cross-reactive characteristics of herpes B virus and herpes simplex virus (HSV) type 1 (HSV-1) and HSV-2 are responsible for false-positive diagnoses by serological assays in humans and macaques. In the present study, we developed a fluorometric indirect enzyme-linked immunosorbent assay (ELISA) with recombinant herpes B virus glycoprotein D (gD) and HSV-1 and HSV-2 gG (gG-1 and gG-2, respectively) to discriminate between the three primate herpesvirus infections. The secreted form of gD, gDdTM, was used to detect antibody to herpes B virus gD. Sera positive for herpes B virus, HSV-1, and HSV-2 showed specific reactions to gD, gG-1, and gG-2, respectively. Sera collected from humans and rhesus macaques were investigated for the presence of antibodies to the recombinant proteins of the three herpesviruses. The results suggested that the approach is able to discriminate between herpes B virus and HSV infections. The ELISA was also found to be able to detect infections with multiple primate herpesviruses and may have the potential to identify a subsequent infection in individuals that have already been infected with another herpesvirus. In addition, we found evidence of a greater cross-reactivity of herpes B virus with HSV-1 than with HSV-2. It is suggested that the ELISA with the recombinant antigens is useful not only for the serodiagnosis of primate herpesvirus infections but also for elucidation of the seroprevalence of herpesviruses in humans and primates

Evaluation of a Rapid Immunochromatographic ODK0501 Assay for Detecting Streptococcus pneumoniae Antigen in Sputum Samples from Patients with Lower Respiratory Tract Infection▿

A novel, rapid, and noninvasive test (ODK0501) to detect Streptococcus pneumoniae antigen was evaluated in a Japanese multicenter study. ODK0501 uses polyclonal antibodies to detect C polysaccharide of S. pneumoniae from sputum samples by an immunochromatographic assay. The utility of ODK0501 was evaluated for 161 adult patients with lower respiratory tract infection between March 2006 and March 2007. Bacterial culture and identification, real-time PCR, and ODK0501 assays were performed on sputum samples, and the Binax Now Streptococcus pneumoniae antigen test was performed using urine samples obtained from the same patients. The performances of all tests were compared based on the results of bacterial culture and identification. The sensitivity and specificity of ODK0501 were 89.1% (49/55 samples) and 95.3% (101/106 samples), respectively. We then compared the Binax Now Streptococcus pneumoniae antigen test with ODK0501 using samples from 142 patients. The sensitivities of ODK0501 and the Binax Now S. pneumoniae antigen test were 90.0% (45/50 samples) and 62.0% (31/50 samples), respectively (P = 0.002). The relative quantity of S. pneumoniae in expectorated sputum was calculated using real-time PCR and indicated that the possibility of false-positive results for ODK0501 due to indigenous S. pneumoniae was low. The positive and negative concordance rates of ODK0501 and Binax Now were 96.8% (30/31 samples) and 21.1% (4/19 samples), respectively. Binax Now was less capable of detecting S. pneumoniae antigen among patients with underlying chronic obstructive pulmonary disease. In conclusion, ODK0501 is noninvasive, rapid, and an accurate tool for diagnosing respiratory infection caused by S. pneumoniae