Performance of VITEK-2 Compact and overnight MicroScan panels for direct identification and susceptibility testing of Gram-negative bacilli from positive FAN BacT/ALERT blood culture bottles.

We describe the reliability of the VITEK-2 Compact and overnight MicroScan panels for direct identification and susceptibility testing from the BacT/ALERT blood culture system when using FAN (FA and FN) bottles. A simple procedure, in two centrifugation steps, was designed to remove the charcoal particles present in FA and FN bottles. A total of 113 positive blood cultures showing Gram-negative rods were investigated. Enterobacteriaceae were isolated in 104 cases, and Pseudomonas aeruginosa in nine. The MicroScan system correctly identified 106 (93.8%) of the 113 isolates. The seven identificaction errors included P. aeruginosa (three), Enterobacter cloacae (one), Escherichia coli (one), Klebsiella oxytoca (one), and Klebsiella pneumoniae (one). The VITEK-2 system correctly identified 109 (96.5%) of the 113 samples obtained directly from the blood culture bottles. The four unidentified isolates were Enterobacter cloacae (two), Escherichia coli (one), and P. aeruginosa (one). MicroScan yielded 4/779 (0.5%) very major errors and 28/2825 (0.9%) minor errors. VITEK-2 yielded 2/550 (0.36%) very major errors, 1/1718 (0.05%) major error, and 32/2373 (1.3%) minor errors. Both systems provided excellent identification (correlation of >90%) and susceptibility (correlation of >98%) results. The average times required to obtain identification and susceptibility results using the direct test applied to the VITEK-2 Compact system were 4.57 +/- 1.37 h and 6.52 +/- 1.64 h, respectively. The VITEK-2 compact system provided results on the same day that the blood culture was found to be positive.

Rapid detection of pneumococcal antigen in serum samples for diagnosing pneumococcal pneumonia.

OBJECTIVES: The aim of the study is to assess the usefulness of C polysaccharide and polysaccharide capsular antigen detection by immunochromatography (ICT) and enzyme immunoassay (EIA), respectively, in serum samples for diagnosing pneumococcal pneumonia. METHODS: Adult patients included in the study were classified in the following groups: In group 1 we studied 101 serum samples from patients with pneumonia due to Streptococcus pneumoniae. In 53 cases the pneumonia was bacteremic. The second group contained 113 serum samples from patients with no pneumococcal pneumonia. Group 3 was made up of 40 serum samples from healthy subjects with no clinical or radiological signs of pneumonia. RESULTS: Using ICT, antigen was detected in 50% of patients with pneumococcal pneumonia, in 64.3 and 40.9% of patients with bacteremic and non-bacteremic pneumococcal pneumonia, respectively. Using EIA, antigens were detected in 35.8% of patients with pneumococcal pneumonia, in 45 and 22.2% of patients with bacteremic and non-bacteremic pneumococcal pneumonia, respectively. CONCLUSIONS: In conclusion, the sensitivity of the tests is low. However, in special situations, where obtaining large volume of urine is difficult, they could be a complementary method in the rapid diagnosis of pneumococcal pneumonia.