Koichiro Kudo

RATIONALE: Pulmonary alveolar microlithiasis is an autosomal recessive disorder in which microliths are formed in the alveolar space. OBJECTIVES: To identify the responsible gene that causes pulmonary alveolar microlithiasis. METHODS: By means of a genomewide single-nucleotide polymorphism analysis using DNA from three patients, we have narrowed the region in which the candidate gene is located. From this region, we have identified a gene that has mutations in all patients with pulmonary alveolar microlithiasis. MEASUREMENTS AND MAIN RESULTS: We identified a candidate gene, SLC34A2, that encodes a type IIb sodium phosphate cotransporter and that is mutated in six of six patients investigated. SLC34A2 is specifically expressed in type II alveolar cells, and the mutations abolished the normal gene function. CONCLUSION: Mutations in the SLC34A2 gene that abolish normal gene function cause pulmonary alveolar microlithiasis.

BACKGROUND: Favipiravir possesses high utility for treating patients with COVID-19. However, research examining the efficacy and safety of favipiravir for patients with COVID-19 is limited. METHODS: We conducted a systematic review of published studies reporting the efficacy of favipiravir against COVID-19. Two investigators independently searched PubMed, the Cochrane Database of Systematic Reviews, MedRxiv, and ClinicalTrials.gov (inception to September 2020) to identify eligible studies. A meta-analysis was performed to measure viral clearance and clinical improvement as the primary outcomes. RESULTS: Among 11 eligible studies, 5 included a comparator group. Comparing to the comparator group, the favipiravir group exhibited significantly better viral clearance on day 7 after the initiation of treatment (odds ratio [OR] = 2.49, 95% confidence interval [CI] = 1.19-5.22), whereas no difference was noted on day 14 (OR = 2.19, 95% CI = 0.69-6.95). Although clinical improvement was significantly better in the favipiravir group on both days 7 and 14, the improvement was better on day 14 (OR = 3.03, 95% CI = 1.17-7.80) than on day 7 (OR = 1.60, 95% CI = 1.03-2.49). The estimated proportions of patients with viral clearance in the favipiravir arm on days 7 and 14 were 65.42 and 88.9%, respectively, versus 43.42 and 78.79%, respectively, in the comparator group. The estimated proportions of patients with clinical improvement on days 7 and 14 in the favipiravir group were 54.33 and 84.63%, respectively, compared with 34.40 and 65.77%, respectively, in the comparator group. CONCLUSIONS: Favipiravir induces viral clearance by 7 days and contributes to clinical improvement within 14 days. The results indicated that favipiravir has strong possibility for treating COVID-19, especially in patients with mild-to-moderate illness. Additional well-designed studies, including examinations of the dose and duration of treatment, are crucial for reaching definitive conclusions.

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.

OBJECTIVE: To establish proper management of Pneumocystis jiroveci pneumonia (PCP) in rheumatoid arthritis (RA) patients treated with infliximab. PCP has been observed in 0.4% of patients with RA treated with infliximab in Japan. METHODS: Data from patients with RA (n = 21) who were diagnosed with PCP during infliximab treatment and from 102 patients with RA who did not develop PCP during infliximab therapy were collected from 14 rheumatology referral centers in Japan. A retrospective review of these patients and a case-control study to compare patients with and without PCP were performed. RESULTS: The median length of time from the first infliximab infusion to the development of PCP was 8.5 weeks. At the onset of PCP, the median dosages of prednisolone and methotrexate were 7.5 mg/day and 8 mg/week, respectively. Pneumocystis jiroveci was microscopically identified in only 2 patients, although the polymerase chain reaction test for the organism was positive in 20 patients. The patients with PCP had significantly lower serum albumin levels (P < 0.001) and lower serum IgG levels (P < 0.001) than the patients without PCP. Computed tomography of the chest in all patients with PCP revealed ground-glass opacity either with sharp demarcation by interlobular septa or without interlobular septal boundaries. Sixteen of the 21 patients with PCP developed acute respiratory failure, but all survived. CONCLUSION: PCP is a serious complication that may occur early in the course of infliximab therapy in patients with RA. For the proper clinical management of this infectious disease, physicians need to be aware of the possibility of PCP developing during infliximab therapy.