Classification of the metallo ß-lactamase subtype produced by the carbapenem-resistant Pseudomonas aeruginosa isolates in Japan.

INTRODUCTION: Multidrug resistant microorganisms are a serious threat to human health. Under the circumstances, a front line of antimicrobials in clinical setting may be carbapenem ß-lactams (CRBP). However, emergence of CRBP resistant (CRBP-r) Gram-negative bacteria are the most alarming. CRBP-r is mainly caused to the production of ß-lactamase, down and up expression of the diffusion channel and the efflux pump genes, respectively. Among them, production of metallo-ß-lactamase (MBL) is a major cause of high-level of CRBP-r. METHOD: We analyzed the MBL subtypes by PCR and DNA sequencing in CRBP-r Psudomonas aeruginosa in the collection of the joint program by the Japanese Association for Infectious Diseases, Japan Society for Clinical Microbiology and Japanese Society of Chemotherapy (2006-2015 in Japan). RESULTS: Among 275 strains out of a total 1716 isolates, 23 (8.3%) were MBL-positive exhibiting resistant to meropenem (MEPM), imipenem, ceftazidime, cefepime, ciprofloxacin and levofloxacin without exception and the MIC of MEPM appeared over 128 µg/mL. Their MBL subtype analysis revealed that 16, 2, and 2 isolates were IMP-1, IMP-7 and VIM-2 positive, respectively, and one isolate each expressed either IMP-10, IMP-34 or IMP-41. CONCLUSIONS: This study revealed that all the MBL-positive CRBP-r isolates were highly resistant to carbapenems dominating IMP-1 production.

Development of an immunochromatographic test for the detection of Mycoplasma pneumoniae GroES antigen.

Mycoplasma pneumoniae frequently causes community-acquired pneumonia in children; ß-lactam antibiotics are ineffective against this bacterium because of its lack of a cell wall. Hence, a rapid and simple detection method is required to ensure appropriate treatment. In this study, we developed a rapid and simple immunochromatography-based detection method using monoclonal antibodies that react with the co-chaperone GroES of M. pneumoniae. Mice were immunized with recombinant GroES, and hybridoma cells producing anti-GroES monoclonal antibodies were established. For the development of the immunochromatographic test, antibody pairs with superior reactivity and specificity were selected. The developed immunochromatographic test could detect 0.1 ng/mL of recombinant GroES within 20 min. Moreover, no cross-reaction was observed with other microorganisms, including six Mycoplasma species, 20 other bacterial species, and one yeast species. Macrolide-resistant and -susceptible M. pneumoniae clinical isolates were detected at approximately 104 to 105 colony-forming units/mL. The study indicates that immunochromatographic tests targeting GroES are useful for rapid and simple detection of M. pneumoniae.