Clonality and Antimicrobial Susceptibility of Burkholderia cepacia complex Isolates Collected from Cystic Fibrosis Patients during 1998-2013 in Bern, Switzerland.

For the first time, we analyzed the clonality and susceptibility of Burkholderia cepacia complex isolates (n=55) collected during 1998-2013 from 44 Swiss cystic fibrosis (CF)-patients. B. cenocepacia (n=28) and B. multivorans (n=14) were mainly of sequence type (ST) 833 and ST874, respectively; B. contaminans isolates were of ST102. Overall, the following MIC50/90s (mg/l) were obtained: piperacillin/tazobactam (≤ 4/≥ 128), ticarcillin/clavulanate (≥ 256/≥256), ceftazidime (2/≥ 32), aztreonam (16/≥ 32), meropenem (2/8), tobramycin (8/≥ 16), minocycline (≤ 1/16), levofloxacin (≤ 0.5/≥ 16), and trimethoprim/sulfamethoxazole (≤ 0.5/4). This is the first survey providing information on the clonality of Bcc detected in Switzerland. Species identification and antimicrobial susceptibility tests should always be routinely performed to adapt more targeted therapies.

Clonal analysis of Inquilinus limosus isolates from six cystic fibrosis patients and specific serum antibody response

Inquilinus limosus is a novel Gram-negative bacterium of the subdivision alpha-Proteobacteria recently found in the airways of patients with cystic fibrosis (CF). Here, the authors report on the clinical courses of six CF patients colonized with I. limosus. Five patients suffered from either an acute respiratory exacerbation or a progressive loss of pulmonary function, whereas one patient was in a stable clinical situation. This study focused on two aims: (i) the clonal analysis of I. limosus isolates by random amplified polymorphic DNA (RAPD)-PCR, and (ii) the clarification of whether the presence of I. limosus in the respiratory tract is associated with a specific serum antibody response. Serum IgG was detected by immunoblotting using I. limosus whole-cell-lysate proteins as antigens. Sera from healthy blood donors (n=10) and from CF patients colonized with Pseudomonas aeruginosa (n=10) were found to be immunoblot negative. All six Inquilinus-positive patients raised serum IgG antibodies against various I. limosus antigens. Surprisingly, in one patient, a specific I. limosus serum antibody response was already detected 1 year prior to Inquilinus-positive sputum cultures. Two prominent antigens were characterized by MALDI-MS: a 23 kDa protein revealed homology to the outer membrane lipoprotein OmlA of Actinobacillus pleuropneumoniae, and an 18 kDa protein to a protein-tyrosine phosphatase of Burkholderia cepacia. In conclusion, detection of I. limosus is accompanied by a specific serum antibody response and may reflect the infectious/pathogenic potential of I. limosus. Moreover, IgG immunoblotting may be useful to detect early infection with I. limosus and may support the selective cultivation of this novel emerging pathogen.

Evaluation of the colorimetric VITEK 2 card for identification of gram-negative nonfermentative rods: comparison to 16S rRNA gene sequencing

Ninety strains of a collection of well-identified clinical isolates of gram-negative nonfermentative rods collected over a period of 5 years were evaluated using the new colorimetric VITEK 2 card. The VITEK 2 colorimetric system identified 53 (59%) of the isolates to the species level and 9 (10%) to the genus level; 28 (31%) isolates were misidentified. An algorithm combining the colorimetric VITEK 2 card and 16S rRNA gene sequencing for adequate identification of gram-negative nonfermentative rods was developed. According to this algorithm, any identification by the colorimetric VITEK 2 card other than Achromobacter xylosoxidans, Acinetobacter sp., Burkholderia cepacia complex, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia should be subjected to 16S rRNA gene sequencing when accurate identification of nonfermentative rods is of concern.