Evaluation of the VITAL (bioMérieux) automated blood culture system using blind subculture

Laboratory Diagnosis of Human Brucellosis

The clinical presentation of brucellosis in humans is variable and unspecific, and thus, laboratory corroboration of the diagnosis is essential for the patient's proper treatment. The diagnosis of brucellar infections can be made by culture, serological tests, and nucleic acid amplification assays. Modern automated blood culture systems enable detection of acute cases of brucellosis within the routine 5- to 7-day incubation protocol employed in clinical microbiology laboratories, although a longer incubation and performance of blind subcultures may be needed for protracted cases. Serological tests, though they lack specificity and provide results that may be difficult to interpret in individuals repeatedly exposed to Brucella organisms, nevertheless remain a diagnostic cornerstone in resource-poor countries. Nucleic acid amplification assays combine exquisite sensitivity, specificity, and safety and enable rapid diagnosis of the disease. However, long-term persistence of positive molecular test results in patients that have apparently fully recovered is common and has unclear clinical significance and therapeutic implications. Therefore, as long as there are no sufficiently validated commercial tests or studies that demonstrate an adequate interlaboratory reproducibility of the different homemade PCR assays, cultures and serological methods will remain the primary tools for the diagnosis and posttherapeutic follow-up of human brucellosis.

Group B Streptococcus vaccine development: present status and future considerations, with emphasis on perspectives for low and middle income countries

Globally, group B Streptococcus (GBS) remains the leading cause of sepsis and meningitis in young infants, with its greatest burden in the first 90 days of life. Intrapartum antibiotic prophylaxis (IAP) for women at risk of transmitting GBS to their newborns has been effective in reducing, but not eliminating, the young infant GBS disease burden in many high income countries. However, identification of women at risk and administration of IAP is very difficult in many low and middle income country (LMIC) settings, and is not possible for home deliveries. Immunization of pregnant women with a GBS vaccine represents an alternate pathway to protecting newborns from GBS disease, through the transplacental antibody transfer to the fetus in utero. This approach to prevent GBS disease in young infants is currently under development, and is approaching late stage clinical evaluation. This manuscript includes a review of the natural history of the disease, global disease burden estimates, diagnosis and existing control options in different settings, the biological rationale for a vaccine including previous supportive studies, analysis of current candidates in development, possible correlates of protection and current status of immunogenicity assays. Future potential vaccine development pathways to licensure and use in LMICs, trial design and implementation options are discussed, with the objective to provide a basis for reflection, rather than recommendations.

Effects of preincubation temperature on the detection of fastidious organisms in delayed-entry samples in the BacT/ALERT 3D blood culture system

This study evaluates the effect of preincubation on delayed-entry samples for fastidious organisms including the HACEK group, Streptococcus species, Neisseria meningitidis, Haemophilus species and Corynebacterium species for the BacT/ALERT 3D System (bioMérieux) using the FA (aerobic) medium. Bottles were inoculated with two different concentrations (0.5 McFarland and a 1:100,000 dilution) of each organism and either loaded into the system immediately or stored at 4 degrees C, room temperature (RT) or 37 degrees C for 24 hours (h) prior to loading. The detection rate (DR) was 92.5% for bottles loaded immediately for both concentrations with a mean time to detection (TTD) of 26.7 h (standard deviation (SD): 14.7 h) for the low concentration and 9.21 h (SD: 5.3 h) for the high concentration. Preincubation at 4 degrees C did not affect the DR for either of the two concentrations in comparison to no preincubation. The DR at RT was 90.0% for the low concentration and 83.6% for the high concentration. At 37 degrees C the DR was 76.3% and 66.3% for the low and the high concentrations respectively. The average TTD was inversely correlated with the preincubation temperature. An incubation of four days was sufficient, with the exception of Eikenella corrodens and Gemella sanguinis. The serotype of Streptococcus pneumoniae or Neisseria meningitidis did not influence the TTD. Kingella kingae remained undetected. For the retrieval of the above mentioned bacteria we recommend storage of bottles at room temperature. In case of erroneous storage at 37 degrees C subcultivation is advisable. All cases with a negative result on day four should be reevaluated and eventually new material for alternative diagnostic procedures should be retrieved.