Wee-Gyo Lee

Vancomycin-Tolerant Streptococcus pneumoniae in Korea

ABSTRACT A nationwide surveillance study was undertaken to monitor antimicrobial resistance among clinical isolates of Streptococcus pneumoniae in Korea, with a special focus on vancomycin tolerance. For the 6-month period from March to August 2002, clinical isolates of S. pneumoniae were collected from 11 university hospitals and 1 reference laboratory. One-hundred eighty-eight isolates were measured for lysis rates after exposure to vancomycin for 4 h. Two vancomycin-tolerant S. pneumoniae (VTSP) strains, S3 and H8, were isolated from sputum cultures of two patients, who had stayed in intensive-care units of different hospitals with long-term antibiotic therapy and were not treated for pneumococcal pneumonia. The penicillin, cefotaxime, and vancomycin MICs for S3 were 8 μg/ml, >16 μg/ml, and 0.5 μg/ml, and those for H8 were 2 μg/ml, 2 μg/ml, and 0.5 μg/ml, respectively. While S3 belonged to serotype 23F and was autolysin defective, H8 belonged to serotype 13F and had intact autolysin. These strains were not clonally related as determined by pulsed-field gel electrophoresis of chromosomal DNA. In agreement with previous reports, both isolates showed pairing of TIGR4 vex2 with R6 pep27 and had two identical amino acid substitutions, Q441K in vncS and N25D in vex2. These findings indicate that two VTSP strains have emerged independently in Korea, suggesting a prevalence rate of 1.1%. The emergence of VTSP would be a serious threat in Korea, where there are significant rates of penicillin resistance in S. pneumoniae. Monitoring of the prevalence of VTSP and further investigation of the clinical relevance of VTSP are warranted.

Hydrogen Isotope Exchange Reactions in an Electrical Discharge

Hydrogen isotope exchange reactions occurring in (H2O, D2)or (D2O, H2) reacting system under a DC electricaldischarge were investigated using spectroscopic methods such asFourier-transform infrared (FTIR) and plasma emission spectroscopy(PES). The progress of the reactions was determined by real-time measurementof the IR absorbance of HDO molecule, a major product of the reaction. Theprogress of the reaction was studied as a function of the temperature, thecurrent density, and the composition of the reactants, while the pressure ofthe system was maintained at approximately 67 mbar. The results revealedthat the discharge method was far more effective in facilating the exchangereaction than was the conventional catalytic method. The (H2O, D2)system also generated a significant amount of D2O besides HDO andHD as the ratio of D2 to H2O was increased. Thetransient species of the system, such as H or D atoms, were monitored duringthe discharge using emission spectroscopy. The analysis of the final products by mass spectroscopy confirmed that neither H2 nor O2was among the major products of the system in the discharge.

Nocardia niigatensis infection in a kidney transplant recipient.

This is the first reported case of Nocardia niigatensis infection in an adult kidney transplant recipient. A 57‐year‐old Asian woman presented with multiple cutaneous abscesses and rapidly growing fungating mass on the left pretibial area for 2 months. She received a cadaveric kidney transplant 4 years previously and was undergoing immunosuppression with prednisolone, cyclosporine and mycophenolate sodium. The microbiological diagnosis was established by isolation of Nocardia from the purulent material expressed from a granule. The strain was identified to the species level by 16S rRNA gene‐targeted PCR. The closest match was with N. niigatensis. Antibiotic treatment (trimethotrim–sulfamethoxazole) was continued for 6 months and the skin lesions improved.

Antifungal susceptibilities to amphotericin B, triazoles and echinocandins of 77 clinical isolates of cryptic Aspergillus species in multicenter surveillance in Korea

We investigated the in vitro antifungal susceptibilities of cryptic Aspergillus species from nine Korean hospitals. Based on the CLSI epidemiological cutoff values, resistance rates to amphotericin B, itraconazole, voriconazole, posaconazole and caspofungin were as follows: A. awamori (34 isolates; all 0%), A. tubingensis (22; 0%, 4.5%, 0%, 0%, and 0%, respectively), A. sydowii (16; 0%, 6.3%, 0%, 0%, and 6.3%), A. lentulus (2; 50%, 0%, 100%, 50%, and 0%), and A. tamarii (2; all 0%). A. calidoustus (one isolate) showed resistance to multiple drugs. Thus, cryptic species identification can be mandatory for clinically important Aspergillus isolates, with their susceptibility data.