Emerging non-13-valent pneumococcal conjugate vaccine (PCV13) serotypes causing adult invasive pneumococcal disease in the late-PCV13 period in Spain

OBJECTIVE

An early reduction of adult invasive pneumococcal disease (IPD) was observed after the 13-valent pneumococcal conjugate vaccine (PCV13) introduction for children in Spain. We analysed the epidemiology of adult IPD in the late-PCV13 period.

METHODS

This was a prospective multicentre study of adult IPD involving six hospitals. Strains were serotyped, genotyped and studied for antimicrobial susceptibility. The late-PCV13 period was compared with the pre- and early-PCV13 periods.

RESULTS

A total of 2197 episodes were collected-949 in 2008-2009, 609 in 2012-2013 and 639 in 2015-2016. The initial decrease of IPD observed (from 12.3/100 000 to 8.1/100 000; 2008-2009 versus 2012-2013) plateaued in 2015-2016 (8.3/100 000). IPD due to PCV13 serotypes decreased (from 7.7 to 3.5 to 2.3/100 000; p < 0.05), whereas IPD caused by non-PCV13 serotypes increased (from 4.5 to 4.6 to 6.0/100 000; p < 0.05). The most frequent serotypes in the late-PCV13 period were: 8 (15.1%), 3 (10.5%), 12F (7.9%) and 9N (5.4%). These serotypes were related to major genotypes: CC53 (59.8%) and CC404 (30.4%) for serotype 8, CC180 (64.1%) and CC260 (28.1%) for serotype 3, CC989 (91.7%) for serotype 12F and CC67 (84.8%) for serotype 9N. Penicillin-non-susceptibility (21.2%) was associated with serotypes 11A (CC156), 14 (CC156) and 19A (CC320), and macrolide-resistance was related to serotypes 24F and 19A. Rates of pneumococcal meningitis remained stable throughout the periods (ranges 0.9, 0.8 and 1.0/100 000).

CONCLUSIONS

The initial decrease of adult IPD observed after PCV13 introduction for children has been balanced by the rise of non-PCV13 serotypes. The spread of antibiotic-resistant lineages related to non-PCV13 serotypes (11A and 24F) could be a threat for the treatment of serious pneumococcal diseases.

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 diagnosis of Staphylococcus aureus bacteremia using S. aureus PNA FISH

In the study presented here, the performance of the S. aureus PNA FISH assay was evaluated using 285 blood cultures (from 104 patients) that had gram-positive cocci resembling staphylococci on Gram stain. The new molecular test is based on a fluorescence in situ hybridization assay using peptide nucleic acid probes targeting Staphylococcus aureus 16S rRNA and is designed for the rapid identification of Staphylococcus aureus directly from positive blood cultures. The sensitivity, specificity, and positive and negative predictive values of the S. aureus PNA FISH for the rapid identification of Staphylococcus aureus directly from positive blood culture bottles were 100, 99.4, 99.2 and 100%, respectively.

Utility of an in-house mycobacteriophage-based assay for rapid detection of rifampin resistance in Mycobacterium tuberculosis clinical isolates

A rapid in-house mycobacteriophage-based assay to identify multidrug resistance by detecting the rifampin susceptibility of Mycobacterium tuberculosis in a microtiter plate format was evaluated. The sensitivity, specificity, and overall accuracy of the assay were 100%. This test is rapid to perform and suitable for widespread implementation.

Evaluation of two different cell lysis methods for releasing mycobacterial nucleic acids in the INNO-LiPA mycobacteria test

The INNO-LiPA Mycobacteria Test (Innogenetics, N.V., Belgium) is a PCR-based reverse hybridization assay for the simultaneous identification of several mycobacterial species. We evaluated two simplified lysis methods for mycobacterial DNA release for application in the INNO-LiPA Mycobacteria Test. The two methods were based on either (i) heat treatment or (ii) sonication. Both methods were performed directly on 45 positive liquid cultures (MB-BacT, BioMérieux, Marcy l'Etoile, France) containing 17 different mycobacterial species. These two simple lysis procedures demonstrated similar effectiveness (100%) to that recommended by the manufacturer. They also significantly shortened the time required for mycobacterial DNA release.