Molecular Characterization of Fluoroquinolone-Resistant Moraxella catarrhalis Variants Generated In Vitro by Stepwise Selection.

Moraxella catarrhalis causes respiratory infections. In this study, fluoroquinolone-resistant strains were selected in vitro to evaluate the mechanism of fluoroquinolone resistance. Strains with reduced fluoroquinolone susceptibility were obtained by stepwise selection in levofloxacin, and fluoroquinolone targets gyr and par were sequenced. Six novel mutations in GyrA (D84Y, T594dup, and A722dup), GyrB (E479K and D439N), and ParE (Q395R) involved in M. catarrhalis resistance to fluoroquinolones were revealed.

Pantoea calida bacteremia in an adult with end-stage stomach cancer under inpatient care.

Pantoea calida is a gram-negative bacillus that was first identified in 2010. Here, we describe the first known case of P. calida bacteremia in a 77-year-old woman with end-stage stomach cancer under inpatient care. The patient was admitted to our hospital for pain after receiving anti-cancer therapy at outpatient facility. Thirteen days after admission, her temperature rose to 39.6 °C. A blood culture was ordered for suspected bacterial infection, and the patient was treated empirically with ampicillin/sulbactam. Cultures showed white pitting colonies later identified as a Pantoea sp. by biochemical analysis. The isolate's 16S rRNA sequence was identical to that of P. calida (100%), and showed 99.1% similarity with that of Pantoea gaviniae. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) confirmed the species as P. calida with an average spectral score >2.0. The primary isolate was ampicillin-resistant, but susceptible to other antibiotics and the bacteremia was cleared after three days of antibiotic therapy. Since P. calida infection is relatively rare, limited information exists on the pathogen's portal of entry and bacterial characteristics; thus, further studies are necessary to establish the pathophysiological mechanisms P. calida infection.

[Contact investigation using QuantiFERON-TB Gold test to evaluate TB exposure in 61 subjects in a hospital setting--(2) Change in QuantiFERON response during one year after exposure].

UNLABELLED: OBJECTIVES & SUBJECTS: The change in IGRA (interferon-gamma release assay, with QuantiFERON-TB Gold, QFT) responses was followed up for one year in a group of contacts of healthcare workers who had been exposed to tuberculosis (TB) infection for a relatively short period in a hospital. The observation was made of a total of 59 close contacts of the index case, where 16 showed positive QFT-conversion and 7 showed the intermediate response ranging 0.1 to 0.35 IU/mL. Three of the conversion cases developed active TB. RESULTS: 67% of the QFT conversions occurred within 2 months of exposure and the others between 2 to 9 months. Those having converted later than 2 months after the exposure showed generally weaker QFT responses than the earlier converters. In response to the treatment to converters (either to latent TB infection or to active TB), 80% of the cases reversed to negative or intermediate. The geometric means of the response values for ESAT-6 and CFP-10 also showed significant decline over the treatment time. DISCUSSIONS: The time profile of responses in the intermediate responders revealed an obviously distinct pattern from that of the negative responders with the values remaining uniformly at very low level throughout, which suggests that this group includes somehow exceptional responders either with or without infection.

[Contact investigation using QuantiFERON-TB Gold test to evaluate TB exposure in 61 subjects in a hospital setting--(1) Outline of the outbreak and its clinical picture].

The index case was a patient who was admitted to a general hospital and treated with pulsed corticosteroid therapy; her breathing was assisted by a respirator. Soon she developed tuberculosis (TB) and died. Immediately after her death, QuantiFERON-TB Gold (QFT) test was conducted in healthcare workers who were in close contact with the index case. From the results of the test, all the healthworkers except 1 were TB negative. However, the QFT test repeated in the healthworkers after 8 weeks was positive in 18.6%. Subsequently, 5 healthworkers, including a doctor, nurses, and radiology technicians, developed TB. Bacterial isolates from 3 of them showed restriction fragment length polymorphism (RFLP) patterns similar to that of the index case. These 3 secondary TB cases included one healthworker who was in contact with the index case for less than 5 min, another whose QFT was negative (or "doubtful" according to the Japanese criterion of the QFT), and a third who was TB positive for QFT test but declined treatment for latent TB infection (LTBI). No other healthworkers or hospitalized patients developed TB. These healthcare workers with TB were further assessed using the QFT test at 6, 9, and 12 months after initial exposure, which showed an additional 4 positive reactors and 4 "doubtful" reactors who were indicated for LTBI treatment. Among these subjects, 7 were those who showed TB positive results 6 months after initial contact. Discussions were made on TB prevention in hospital settings including contact investigations the staff with special reference to application of the QFT test.

Evaluation of the modified carbapenem inactivation method and sodium mercaptoacetate-combination method for the detection of metallo-ß-lactamase production by carbapenemase-producing Enterobacteriaceae.

We evaluated the effectiveness of carbapenem inactivation method (CIM) and modified CIM (mCIM). Our results indicated that mCIM with 4h incubation improved sensitivity and specificity for detecting carbapenemase-producing Enterobacteriaceae compared to CIM. Additionally, we developed a sodium mercaptoacetate-combination method (SMA-mCIM) to detect metallo-ß-lactamase (MBL) with high sensitivity and specificity.

Comparison of the Modified-Hodge test, Carba NP test, and carbapenem inactivation method as screening methods for carbapenemase-producing Enterobacteriaceae.

We compared three screening methods for carbapenemase-producing Enterobacteriaceae. While the Modified-Hodge test and Carba NP test produced false-negative results for OXA-48-like and mucoid NDM producers, the carbapenem inactivation method (CIM) showed positive results for these isolates. Although the CIM required cultivation time, it is well suited for general clinical laboratories.