A Modified Carbapenem Inactivation Method, CIMTris, for Carbapenemase Production in Acinetobacter and Pseudomonas Species.

The carbapenem inactivation method (CIM) and modified CIM (mCIM) are simple and economical phenotypic screening methods for detecting carbapenemase production in Gram-negative bacteria. Although the mCIM has been recommended by the Clinical and Laboratory Standards Institute, both the CIM and mCIM have limitations. This study describes another modified CIM, called CIMTris, in which carbapenemase was extracted from bacteria with 0.5 M Tris-HCl (pH 7.6) buffer. The ability of the CIMTris to detect carbapenemase production was examined in Acinetobacter and Pseudomonas species. The CIMTris had an overall sensitivity of 97.6% and an overall specificity of 92.6%, whereas the mCIM had a sensitivity of 45.1% and a specificity of 100% for the isolates tested. These findings indicate that the CIMTris is useful for detecting carbapenemase production in Acinetobacter and Pseudomonas species.

Meningococcal pneumonia in Japan: A case report and literature review.

Neisseria meningitidis often causes meningitis and meningococcemia; however, meningococcal pneumonia is quite rare. Herein, we report a case of non-invasive meningococcal pneumonia initially misdiagnosed as pneumonia due to Moraxella catarrhalis on the basis of a Gram stain in a 43-year-old woman with asthma, type 2 diabetes mellitus, and schizophrenia. She visited our hospital following a 3-day history of fever, productive cough, and shortness of breath. Since her sputum smear revealed Gram-negative diplococcus and the chest radiograph showed infiltration in the lower right lung field, her initial diagnosis was pneumonia caused by M. catarrhalis. However, the next day, the sputum culture colonies were unlike those of M. catarrhalis, and matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis revealed the pathogen to be N. meningitidis. As a result, we administered the appropriate treatment and ensured adequate infection prevention and control measures including, droplet precautions and prophylaxis provided to close contacts. Secondary infection did not occur. Although meningococcal pneumonia is not common, physicians should consider N. meningitidis when Gram-negative diplococci are observed in respiratory specimens, as N. meningitidis cannot be distinguished from M. catarrhalis with Gram staining alone. Moreover, it is also important to monitor the appearance of the pathogenic colonies and to closely coordinate with laboratory technicians to determine appropriate treatments. In this article, we review the previous case reports of meningococcal pneumonia reported in 1984-2015 in Japan, summarizing the clinical characteristics and comparing previous reviews of the literature.

Emergence of a multidrug-resistant plasmid encoding bla NDM-1, bla OXA-420 and armA in a clinical isolate of Acinetobacter variabilis in Japan.

Acinetobacter variabilis (formerly genospecies 15 sensu Tjernberg and Ursing) has been isolated from humans and animals and was proposed to be a novel species in 2015. A multidrug-resistant A. variabilis isolate, RYU24, was obtained in 2012 from an inpatient in Okinawa, Japan, with no record of overseas travel. The isolate was resistant to carbapenems, aminoglycosides and ciprofloxacin, with minimum inhibitory concentrations (MICs) of 32 µg ml-1 for imipenem and meropenem; > 1024 µg ml-1 for amikacin, arbekacin, gentamicin and tobramycin; and 8 µg ml-1 for ciprofloxacin. The isolate was found to harbour a 68-kbp plasmid carrying bla NDM-1, which encodes New Delhi metallo-ß-lactamase-1 (NDM-1); bla OXA-420, which encodes an OXA-58-like carbapenemase and; armA, which encodes ArmA 16S rRNA methylase conferring pan-aminoglycoside resistance. To our knowledge, this is the first report of a plasmid harbouring the three major drug-resistance genes, bla NDM-1, bla OXA-420 and armA.

An improved carbapenem inactivation method, CIMTrisII, for carbapenemase production by Gram-negative pathogens.

The modified carbapenem inactivation method (mCIM) is a simple phenotypic screening method for detecting carbapenemase production by Enterobacteriaceae and Pseudomonas aeruginosa. We recently developed another modified carbapenem inactivation method (CIMTris), in which carbapenemase is extracted from bacteria with Tris-HCl buffer, to detect carbapenemase production by Acinetobacter and Pseudomonas species. This study describes an improved carbapenem inactivation method, CIMTrisII, for detecting carbapenemase production by Gram-negative pathogens, including Enterobacteriaceae, Acinetobacter and Pseudomonas species. CIMTrisII was different from CIMTris in the concentration of Meropenem disks (5-µg MEM disks vs. 10-µg MEM disks), the inoculum volume of the bacteria (a 5-µl loopful vs. a 10 µl loopful) and the incubation time (1 vs. 2 h). CIMTrisII showed an overall sensitivity of 99.3 % and an overall specificity of 95.0 % for tested isolates. In comparison, CIMTris showed a sensitivity of 96.1 % and a specificity of 96.3 %, and mCIM showed a sensitivity of 67.1 % and a specificity of 100 %. CIMTrisII is thus deemed useful for detecting carbapenemase production by Gram-negative pathogens.