Although Korea is one of the endemic areas for hepatitis B virus infection (HBV), the prevalence of deletions in HBV preS region occurring naturally have not been determined. In the present study, the prevalence of preS deletions was determined in terms of clinical state and HBeAg serostatus in 120 patients with different clinical features [59 HBeAg positive, 61 HBeAg negative; 38 asymptomatic carriers, 21 patients with chronic hepatitis, 21 patients with liver cirrhosis, 40 patients with hepatocellular carcinoma (HCC)]. A total of 37 strains (30.8%) harbored deletions in the preS region. Overall, the frequencies of preS deletions tended to increase gradually according to the degree of the clinical severity of liver disease. The prevalence of preS1 deletions in HCC patients tended to be higher than in patients with liver cirrhosis (32.5% vs. 19%). The prevalence of preS2 deletions in HBeAg negative patients was significantly higher than in HBeAg positive patients (23% vs. 6.8%). The type of deletion encountered most frequently was one disrupting the preS1 start codon [14/37 strains (37.8%)], which showed a very high prevalence in HCC patients (9/40, 22.5%; HCC vs. asymptomatic carriers, P=0.048). These results suggest that there might be the discrepancy between preS1 and preS2 mutations in the mechanism of enhancing the progression of chronic liver disease, especially the development of HCC and to maintain tolerance during the stage of immune tolerance. Specific deletion of the type disrupting preS1 start codon may play important roles in hepatocarcinogenesis, at least in Korean patients with chronic HBV infection.

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Of the validated species in the genus Mycobacterium, M. tuberculosis is the most common and important pathogen and causes 2 million deaths and over 8 million cases of tuberculosis annually worldwide (2-4, 7). In addition to the multidrug resistant strains of M. tuberculosis, NTM (non-tuberculosis mycobacteria) infection can cause other serious clinical problems. Moreover, because the drugs of choice for the treatment of NTM infection are heavily dependent on taxonomic statuses (15,19,20), it is of importance that we are able to differentiate these at the species level during early diagnostic procedures.The classical identification of mycobacteria based on cultural and biochemical tests may take several weeks, and sometimes, even then, may fail to provide a precise identification. To resolve such disadvantages of conventional methods, various PCR-mediated methods have been applied for the rapid detection and identification of mycobacteria species. Among these, PCRrestriction analysis (PRA) is preferred, since it offers an easy, rapid, and inexpensive means of identifying mycobacteria species. Thus, a number of PRA methods targeting several chronometers, such as, 16S rDNA (6, 8), hsp65 (5, 17), dnaJ (16), and rpoB (11), have been developed. However, although these PRA techniques have been successfully applied to mycobacteria identification at the culture level, problems are encountered when they are applied directly to clinical specimens, especially sputum samples, which also contain numbers of commensal bacteria from the respiratory tract, because these bacteria produce complex PRA patterns that are difficult to interpret.Previously, we reported that a novel PRA method that targets 644 bp hsp65 DNA is useful for the differentiation of mycobacterial species at the culture level (12). In particular, by only the use of a single restriction enzyme, AvaII, it can differentiate the three most clinically important mycobacteria species, i.e., M. tuberculosis and two MACs, M. avium and M. intracellulare. Moreover, the simplicity of this PRA method might enable the direct detection of pathogenic mycobacteria from clinical specimens such as sputum.In the present study, to evaluate the usefulness of the AvaII PRA method targeting 644-bp hsp65 sequence Abstract: To evaluate the usefulness of the AvaII PRA method targeting 644-bp hsp65 gene for the direct detection of pathogenic mycobacteria from clinical specimens, we applied this method to 40 sputum samples and compared the results to those obtained by IS6110 PCR. Although this method showed a sensitivity slightly lower than IS6110 PCR (97.5% vs. 100%), it detected infections of M. avium complex (MAC) in two patients, which was not possible by IS6110 PCR. We conclude that AvaII PRA is a highly effective method for directly detecting pathogenic mycobacteria in primary clinical specimens.

Mycobacterium xenopi is a nontuberculous mycobacterium (NTM) that rarely causes pulmonary disease in Asia. Here we describe the first case of M. xenopi pulmonary disease in Korea. A 66-year-old man was admitted to our hospital with a 2-month history of productive cough and hemoptysis. His past medical history included pulmonary tuberculosis 44 years earlier, leading to a right upper lobectomy. Chest X-ray upon admission revealed cavitary consolidation involving the entire right lung. Numerous acid-fast bacilli were seen in his initial sputum, and M. xenopi was subsequently identified in more than five sputum cultures, using molecular methods. Despite treatment with clarithromycin, rifampicin, ethambutol, and streptomycin, the infiltrative shadow revealed on chest X-ray increased in size. The patient's condition worsened, and a right completion pneumonectomy was performed. The patient consequently died of respiratory failure on postoperative day 47, secondary to the development of a late bronchopleural fistula. This case serves as a reminder to clinicians that the incidence of NTM infection is increasing in Korea and that unusual NTM are capable of causing disease in non-immunocompromised patients.