16S rRNA gene sequencing versus the API 20 NE system and the VITEK 2 ID-GNB card for identification of nonfermenting Gram-negative bacteria in the clinical laboratory.

Over a period of 26 months, we have evaluated in a prospective fashion the use of 16S rRNA gene sequencing as a means of identifying clinically relevant isolates of nonfermenting gram-negative bacilli (non-Pseudomonas aeruginosa) in the microbiology laboratory. The study was designed to compare phenotypic with molecular identification. Results of molecular analyses were compared with two commercially available identification systems (API 20 NE, VITEK 2 fluorescent card; bioMérieux, Marcy l'Etoile, France). By 16S rRNA gene sequence analyses, 92% of the isolates were assigned to species level and 8% to genus level. Using API 20 NE, 54% of the isolates were assigned to species and 7% to genus level, and 39% of the isolates could not be discriminated at any taxonomic level. The respective numbers for VITEK 2 were 53%, 1%, and 46%, respectively. Fifteen percent and 43% of the isolates corresponded to species not included in the API 20 NE and VITEK 2 databases, respectively. We conclude that 16S rRNA gene sequencing is an effective means for the identification of clinically relevant nonfermenting gram-negative bacilli. Based on our experience, we propose an algorithm for proper identification of nonfermenting gram-negative bacilli in the diagnostic laboratory.

Family planning in Britain.

PIP: In Britain in 1968 there were 780 family planning clinics using all conventional methods except IUDs and 220 IUD clinics. In 1967 of 173,000 new patients, 77,000 chose oral contraceptives, 60,000 chose diaphragms, and 24,000 chose IUDs. A short training course is given to both nurses and doctors. The Family Planning Association is the private agency responsible for promoting birth control advice, information, and services. Since the Family Planning Act was passed in 1967, the National Health Service has the authority to provide family planning service to those who want it for free.^ieng

Reliable detection of respiratory syncytial virus infection in children for adequate hospital infection control management.

By using a rapid test for respiratory syncytial virus (RSV) detection (Abbott TestPack RSV), a number of patients were observed, showing repeatedly positive results over a period of up to 10 weeks. A prospective study was initiated to compare the rapid test with an antigen capture enzyme immunoassay (EIA) and a nested reverse transcriptase PCR (RT-PCR) protocol for detection of RSV serotypes A and B. Only respiratory samples from children exhibiting the prolonged presence of RSV (> or =5 days) as determined by the rapid test were considered. A total of 134 specimens from 24 children was investigated by antigen capture EIA and nested RT-PCR. Using RT-PCR as the reference method, we determined the RSV rapid test to have a specificity of 63% and a sensitivity of 66% and the antigen capture EIA to have a specificity of 96% and a sensitivity of 69% for acute-phase samples and the homologous virus serotype A. In 7 (29%) of 24 patients, the positive results of the RSV rapid test could not be confirmed by either nested RT-PCR or antigen capture EIA. In these seven patients a variety of other respiratory viruses were detected. For general screening the RSV rapid test was found to be a reasonable tool to get quick results. However, its lack of specificity in some patients requires confirmation by additional tests to rule out false-positive results and/or detection of other respiratory viruses.

Comparison of conventional and molecular methods for identification of aerobic catalase-negative gram-positive cocci in the clinical laboratory.

Over a period of 18 months we have evaluated the use of 16S ribosomal DNA (rDNA) sequence analysis as a means of identifying aerobic catalase-negative gram-positive cocci in the clinical laboratory. A total of 171 clinically relevant strains were studied. The results of molecular analyses were compared with those obtained with a commercially available phenotypic identification system (API 20 Strep system; bioMérieux sa, Marcy l'Etoile, France). Phenotypic characterization identified 67 (39%) isolates to the species level and 32 (19%) to the genus level. Seventy-two (42%) isolates could not be discriminated at any taxonomic level. In comparison, 16S rDNA sequencing identified 138 (81%) isolates to the species level and 33 (19%) to the genus level. For 42 of 67 isolates assigned to a species with the API 20 Strep system, molecular analyses yielded discrepant results. Upon further analysis it was concluded that among the 42 isolates with discrepant results, 16S rDNA sequencing was correct for 32 isolates, the phenotypic identification was correct for 2 isolates, and the results for 8 isolates remained unresolved. We conclude that 16S rDNA sequencing is an effective means for the identification of aerobic catalase-negative gram-positive cocci. With the exception of Streptococcus pneumoniae and beta-hemolytic streptococci, we propose the use of 16S rDNA sequence analysis if adequate species identification is of concern.

Ribosomal DNA sequencing for identification of aerobic gram-positive rods in the clinical laboratory (an 18-month evaluation).

We have evaluated over a period of 18 months the use of 16S ribosomal DNA (rDNA) sequence analysis as a means of identifying aerobic gram-positive rods in the clinical laboratory. Two collections of strains were studied: (i) 37 clinical strains of gram-positive rods well identified by phenotypic tests, and (ii) 136 clinical isolates difficult to identify by standard microbiological investigations, i.e., identification at the species level was impossible. Results of molecular analyses were compared with those of conventional phenotypic identification procedures. Good overall agreement between phenotypic and molecular identification procedures was found for the collection of 37 clinical strains well identified by conventional means. For the 136 clinical strains which were difficult to identify by standard microbiological investigations, phenotypic characterization identified 71 of 136 (52.2%) isolates at the genus level; 65 of 136 (47.8%) isolates could not be discriminated at any taxonomic level. In comparison, 16S rDNA sequencing identified 89 of 136 (65.4%) isolates at the species level, 43 of 136 (31.6%) isolates at the genus level, and 4 of 136 (2.9%) isolates at the family level. We conclude that (i) rDNA sequencing is an effective means for the identification of aerobic gram-positive rods which are difficult to identify by conventional techniques, and (ii) molecular identification procedures are not required for isolates well identified by phenotypic investigations.