We hypothesized that host antiviral genes induced by type I interferons might affect the natural course of severe acute respiratory syndrome (SARS). We analyzed single nucleotide polymorphisms (SNPs) of 2',5'-oligoadenylate synthetase 1 (OAS-1), myxovirus resistance-A (MxA), and double-stranded RNA-dependent protein kinase in 44 Vietnamese SARS patients with 103 controls. The G-allele of non-synonymous A/G SNP in exon 3 of OAS-1 gene showed association with SARS (p=0.0090). The G-allele in exon 3 of OAS-1 and the one in exon 6 were in strong linkage disequilibrium and both of them were associated with SARS infection. The GG genotype and G-allele of G/T SNP at position -88 in the MxA gene promoter were found more frequently in hypoxemic group than in non-hypoxemic group of SARS (p=0.0195). Our findings suggest that polymorphisms of two IFN-inducible genes OAS-1 and MxA might affect susceptibility to the disease and progression of SARS at each level.

We developed a DNA sequencing-based method to detect mutations in the genome of drug-resistant Mycobacterium tuberculosis. Drug resistance in M. tuberculosis is caused by mutations in restricted regions of the genome. Eight genome regions associated with drug resistance, including rpoB for rifampin (RIF), katG and the mabA (fabG1)-inhA promoter for isoniazid (INH), embB for ethambutol (EMB), pncA for pyrazinamide (PZA), rpsL and rrs for streptomycin (STR), and gyrA for levofloxacin, were amplified simultaneously by PCR, and the DNA sequences were determined. It took 6.5 h to complete all procedures. Among the 138 clinical isolates tested, 55 were resistant to at least one drug. Thirty-four of 38 INH-resistant isolates (89.5%), 28 of 28 RIF-resistant isolates (100%), 15 of 18 EMB-resistant isolates (83.3%), 18 of 30 STR-resistant isolates (60%), and 17 of 17 PZA-resistant isolates (100%) had mutations related to specific drug resistance. Eighteen of these mutations had not been reported previously. These novel mutations include one in rpoB, eight in katG, one in the mabA-inhA regulatory region, two in embB, five in pncA, and one in rrs. Escherichia coli isolates expressing individually five of the eight katG mutations showed loss of catalase and INH oxidation activities, and isolates carrying any of the five pncA mutations showed no pyrazinamidase activity, indicating that these mutations are associated with INH and PZA resistance, respectively. Our sequencing-based method was also useful for testing sputa from tuberculosis patients and for screening of mutations in Mycobacterium bovis. In conclusion, our new method is useful for rapid detection of multiple-drug-resistant M. tuberculosis and for identifying novel mutations in drug-resistant M. tuberculosis.The emergence and spread of drug-resistant strains of Mycobacterium tuberculosis, especially multidrug-resistant (MDR) strains, are serious threats to the control of tuberculosis and comprise an increasing public health problem (40). Patients infected with MDR strains, which are defined as strains resistant to both rifampin (RIF) and isoniazid (INH), are difficult to cure and are more likely to remain sources of infection for a longer period of time than are patients with drug-susceptible strains (40).It is essential that rapid drug susceptibility tests be developed to prevent the spread of MDR M. tuberculosis. The time necessary for culture of specimens was reduced by the radiometric BACTEC 460TB system (BD Biosciences, Sparks, MD), the nonradiometric ESP II system (Trek Diagnostics, Westlake, OH), and other rapid broth methods, such as BACTEC MGIT 960 SIRE (BD Biosciences) (20). These drug susceptibility tests, however, still require 1 to 2 weeks for final determination and reporting to the clinician (23). Additional reductions in the detection period are needed.Drug resistance in M. tuberculosis is caused by mutations in relatively restricted regions of the genome (17, 39). Mutations associated with drug resistance occur in rpoB for RIF, katG and the promote...

We have hypothesized that genetic predisposition influences the progression of SARS. Angiotensin converting enzyme (ACE1) insertion/deletion (I/D) polymorphism was previously reported to show association with the adult respiratory distress syndrome, which is also thought to play a key role in damaging the lung tissues in SARS cases. This time, the polymorphism was genotyped in 44 Vietnamese SARS cases, with 103 healthy controls who had had a contact with the SARS patients and 50 controls without any contact history. SARS cases were divided into either non-hypoxemic or hypoxemic groups. Despite the small sample size, the frequency of the D allele was significantly higher in the hypoxemic group than in the non-hypoxemic group (p=0.013), whereas there was no significant difference between the SARS cases and controls, irrespective of a contact history. ACE1 might be one of the candidate genes that influence the progression of pneumonia in SARS.

We previously reported an outbreak in a neurosurgery ward of catheter-associated urinary tract infection with multidrug-resistant (MDR) Pseudomonas aeruginosa strain IMCJ2.S1, carrying the 6-N-aminoglycoside acetyltransferase gene [aac(6)-Iae]. For further epidemiologic studies, 214 clinical isolates of MDR P. aeruginosa showing resistance to imipenem (MIC > 16 g/ml), amikacin (MIC > 64 g/ml), and ciprofloxacin (MIC > 4 g/ml) were collected from 13 hospitals in the same prefecture in Japan. We also collected 70 clinical isolates of P. aeruginosa that were sensitive to one or more of these antibiotics and compared their characteristics with those of the MDR P. aeruginosa isolates. Of the 214 MDR P. aeruginosa isolates, 212 (99%) were serotype O11. We developed a loop-mediated isothermal amplification (LAMP) assay and a slide agglutination test for detection of the aac(6)-Iae gene and the AAC(6)-Iae protein, respectively. Of the 212 MDR P. aeruginosa isolates, 212 (100%) and 207 (98%) were positive in the LAMP assay and in the agglutination test, respectively. Mutations of gyrA and parC genes resulting in amino acid substitutions were detected in 213 of the 214 MDR P. aeruginosa isolates (99%). Of the 214 MDR P. aeruginosa isolates, 212 showed pulsed-field gel electrophoresis patterns with >70% similarity to that of IMCJ2.S1 and 83 showed a pattern identical to that of IMCJ2.S1, indicating that clonal expansion of MDR P. aeruginosa occurred in community hospitals in this area. The methods developed in this study to detect aac(6)-Iae were rapid and effective in diagnosing infections caused by various MDR P. aeruginosa clones.Pseudomonas aeruginosa causes nosocomial infections as a result of its ubiquitous nature, ability to survive in moist environments, and resistance to many antibiotics and antiseptics. A serious problem is the emergence of multidrug-resistant (MDR) P. aeruginosa strains resistant to ␤-lactams, aminoglycosides, and quinolones (34,39,46 We previously reported a nosocomial outbreak of catheterassociated urinary tract infection involving new MDR P. aeruginosa strain IMCJ2.S1, which occurred in a neurosurgery ward of a hospital located in the Tohoku area of Japan (46). This strain showed broad-spectrum resistance to aminoglycosides, ␤-lactams, fluoroquinolones, tetracyclines, sulfonamide, and chlorhexidine. We found that IMCJ2.S1 harbored a novel class 1 integron, In113, containing an array of three gene cassettes of the metallo-␤-lactamase (MBL) bla IMP-1 gene, aminoglycoside 6Ј-acetyltransferase aac(6Ј)-Iae gene, and aminoglycoside 3Ј-adenylyltransferase aadA1 gene (46). This strain possessed mutations of the gyrA (83Thr3Ile) and parC (87Ser3Leu) genes involving amino acid substitutions, resulting in high-level resistance to fluoroquinolones.In the geographic area where the MDR P. aeruginosa outbreak occurred (46), hospitals and a commercial clinical laboratory were surveyed for similar organisms. Because 99% of the MDR P. aeruginosa isolates analyzed were found to harbor the aac(6Ј)-Iae gene, we d...