Molecular Evolutionary Analyses of Shiga toxin type 2 subunit A Gene in the Enterohemorrhagic Escherichia coli (EHEC).

To better understand the molecular genetics of the Shiga toxin type 2 subunit A gene (stx2A gene), we collected many subtypes of stx2A genes and performed detailed molecular evolutionary analyses of the gene. To achieve the aim of the study, we used several bioinformatics technologies, including time-scaled phylogenetic analyses, phylogenetic distance analyses, phylodynamics analyses, selective pressure analyses, and conformational epitope analyses. A time-scaled phylogeny showed that the common ancestor of the stx2A gene dated back to around 18,600 years ago. After that, the gene diverged into two major lineages (Lineage 1 and 2). Lineage 1 comprised the stx2a-2d subtypes, while Lineage 2 comprised the stx2e, 2g, 2h, and 2o subtypes. The evolutionary rates of the genes were relatively fast. Phylogenetic distances showed that the Lineage 2 strains had a wider genetic divergence than Lineage 1. Phylodynamics also indicated that the population size of the stx2A gene increased after the 1930s and spread globally. Moreover, negative selection sites were identified in the Stx2A proteins, and these sites were diffusely distributed throughout the protein. Two negative selection sites were located adjacent to an active site of the common Stx2A protein. Many conformational epitopes were also estimated in these proteins, while no conformational epitope was found adjacent to the active site. The results suggest that the stx2A gene has uniquely evolved and diverged over an extremely long time, resulting in many subtypes. The dominance of the strains belonging to Lineage 1 suggests that differences in virulence may be involved in the prosperity of the offspring. Furthermore, some subtypes of Stx2A proteins may be able to induce effective neutralizing antibodies against the proteins in humans.

Epidemiological Features of Human Norovirus Genotypes before and after COVID-19 Countermeasures in Osaka, Japan.

We investigated the molecular epidemiology of human norovirus (HuNoV) in all age groups using samples from April 2019 to March 2023, before and after the COVID-19 countermeasures were implemented. GII.2[P16] and GII.4[P31], the prevalent strains in Japan before COVID-19 countermeasures, remained prevalent during the COVID-19 pandemic, except from April to November 2020; in 2021, the prevalence of GII.2[P16] increased among children. Furthermore, there was an increase in the prevalence of GII.4[P16] after December 2022. Phylogenetic analysis of GII.P31 RdRp showed that some strains detected in 2022 belonged to a different cluster of other strains obtained during the present study period, suggesting that HuNoV strains will evolve differently even if they have the same type of RdRp. An analysis of the amino acid sequence of VP1 showed that some antigenic sites of GII.4[P16] were different from those of GII.4[P31]. The present study showed high infectivity of HuNoV despite the COVID-19 countermeasures and revealed changes in the prevalent genotypes and mutations of each genotype. In the future, we will investigate whether GII.4[P16] becomes more prevalent, providing new insights by comparing the new data with those analyzed in the present study.

Assessment of Patient Characteristics Influencing the Analgesic Effects of Ibuprofen Gargle After Mandibular Third Molar Extractions.

Introduction In our previous work, we investigated the analgesic effects of ibuprofen gargle after mandibular third molar extractions. However, a subsequent detailed review of individual patient data revealed variations in postoperative pain reduction among patients. Consequently, the present study was designed to conduct post-hoc subanalyses that identified factors contributing to variation in the analgesic response to ibuprofen gargle after third molar extractions. Materials and methods This study involved thirty-five Japanese patients from a prior randomized, double-blind, placebo-controlled, crossover study, which focused on the analgesic effects of ibuprofen gargle after mandibular third molar extractions. Participants were categorized as responders (n = 13) and non-responders (n = 22) based on the within-subject difference (ibuprofen-placebo, IP) of visual analog scale (VAS) changes. Baseline characteristics were compared, along with variables, such as age, sex, the reason for extraction, extraction site, Pell Gregory (space and depth) classification, Winter's classification, surgeon's experience, and surgery time. Baseline characteristics predicting responder status were examined using multivariate logistic regression. Results In the univariate analysis, variables such as age, sex, and baseline VAS scores with p-values <0.2 were evaluated using a stepwise approach. This analysis identified age (per -10 years) with an odds ratio of 4.163 (95% confidence interval (CI): 1.170-31.952, p = 0.0233) and sex (female) with an odds ratio of 9.977 (95% CI: 1.336-208.256, p = 0.0213) as significant predictors of responder status. Conclusions In young and female patients, ibuprofen gargle decreased postoperative pain after mandibular third molar extractions.

Efficacy and safety of ibuprofen gargle for postoperative pain after mandibular third molar extraction: A phase II, placebo-controlled, double-blind, randomized crossover trial.

OBJECTIVE: This study was designed to evaluate the postoperative efficacy and safety of using an ibuprofen gargle as a pain management strategy for patients who have undergone mandibular third molar extraction. We also ensured that the quality of treatment was not compromised throughout the study. MATERIAL AND METHODS: Patients were randomized in a 1:1 ratio into two groups: the ibuprofen-placebo (IP) group and the placebo-ibuprofen (PI) group. On postoperative Day (POD) 1, the IP group initiated ibuprofen administration, while the PI group started taking placebo. On POD 2, the IP group switched to using placebo, whereas the PI group switched to ibuprofen. From PODs 3-5, both groups were prescribed ibuprofen gargle. The primary endpoint was within-subject visual analog scale (VAS) score before and 5 min after the first use of the ibuprofen or placebo gargle on PODs 1 and 2 (ΔVAS5_ibuprofen - ΔVAS5_placebo ). The incidence and severity of adverse events were assessed using the Common Terminology Criteria for Adverse Events version 5.0 and a subjective rating scale. RESULTS: This study enrolled 40 patients. The within-subject VAS5 of the IP and PI groups were 1.25 ± 12.0 and -5.26 ± 8.93 mm, respectively. The treatment effect of ibuprofen gargle was -2.01 ± 10.62 mm (p = .246). None of the patients in each group presented with serious adverse events or clinically significant complications (including dry sockets) after extraction. Transient adverse events, such as throat tingling and oral discomfort (grade 1), were observed in each group. CONCLUSION: Ibuprofen gargle was safe but did not provide significant pain relief when used after mandibular third molar extraction.

Pathogen Profiles in Outpatients with Non-COVID-19 during the 7th Prevalent Period of COVID-19 in Gunma, Japan.

The identification of pathogens associated with respiratory symptoms other than the novel coronavirus disease 2019 (COVID-19) can be challenging. However, the diagnosis of pathogens is crucial for assessing the clinical outcome of patients. We comprehensively profiled pathogens causing non-COVID-19 respiratory symptoms during the 7th prevalent period in Gunma, Japan, using deep sequencing combined with a next-generation sequencer (NGS) and advanced bioinformatics technologies. The study included nasopharyngeal swabs from 40 patients who tested negative for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) using immuno-chromatography and/or quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods. Comprehensive pathogen sequencing was conducted through deep sequencing using NGS. Additionally, short reads obtained from NGS were analyzed for comprehensive pathogen estimation using MePIC (Metagenomic Pathogen Identification Pipeline for Clinical Specimens) and/or VirusTap. The results revealed the presence of various pathogens, including respiratory viruses and bacteria, in the present subjects. Notably, human adenovirus (HAdV) was the most frequently detected virus in 16 of the 40 cases (40.0%), followed by coryneforms, which were the most frequently detected bacteria in 21 of the 40 cases (52.5%). Seasonal human coronaviruses (NL63 type, 229E type, HKU1 type, and OC43 type), human bocaviruses, and human herpesviruses (human herpesvirus types 1-7) were not detected. Moreover, multiple pathogens were detected in 50% of the subjects. These results suggest that various respiratory pathogens may be associated with non-COVID-19 patients during the 7th prevalent period in Gunma Prefecture, Japan. Consequently, for an accurate diagnosis of pathogens causing respiratory infections, detailed pathogen analyses may be necessary. Furthermore, it is possible that various pathogens, excluding SARS-CoV-2, may be linked to fever and/or respiratory infections even during the COVID-19 pandemic.

Molecular Evolutionary Analyses of the Spike Protein Gene and Spike Protein in the SARS-CoV-2 Omicron Subvariants.

To better understand the evolution of the SARS-CoV-2 Omicron subvariants, we performed molecular evolutionary analyses of the spike (S) protein gene/S protein using advanced bioinformatics technologies. First, time-scaled phylogenetic analysis estimated that a common ancestor of the Wuhan, Alpha, Beta, Delta variants, and Omicron variants/subvariants diverged in May 2020. After that, a common ancestor of the Omicron variant generated various Omicron subvariants over one year. Furthermore, a chimeric virus between the BM.1.1.1 and BJ.1 subvariants, known as XBB, diverged in July 2021, leading to the emergence of the prevalent subvariants XBB.1.5 and XBB.1.16. Next, similarity plot (SimPlot) data estimated that the recombination point (breakpoint) corresponded to nucleotide position 1373. As a result, XBB.1.5 subvariants had the 5' nucleotide side from the breakpoint as a strain with a BJ.1 sequence and the 3' nucleotide side as a strain with a BM.1.1.1 sequence. Genome network data showed that Omicron subvariants were genetically linked with the common ancestors of the Wuhan and Delta variants, resulting in many amino acid mutations. Selective pressure analysis estimated that the prevalent subvariants, XBB.1.5 and XBB.1.16, had specific amino acid mutations, such as V445P, G446S, N460K, and F486P, located in the RBD when compared with the BA.4 and BA.5 subvariants. Moreover, some representative immunogenicity-associated amino acid mutations, including L452R, F486V, R493Q, and V490S, were also found in these subvariants. These substitutions were involved in the conformational epitopes, implying that these mutations affect immunogenicity and vaccine evasion. Furthermore, these mutations were identified as positive selection sites. These results suggest that the S gene/S protein Omicron subvariants rapidly evolved, and mutations observed in the conformational epitopes may reduce the effectiveness of the current vaccine, including bivalent vaccines such as mRNA vaccines containing the BA.4/BA.5 subvariants.

Molecular Evolutionary Analyses of the RNA-Dependent RNA Polymerase (RdRp) Region and VP1 Gene in Human Norovirus Genotypes GII.P6-GII.6 and GII.P7-GII.6.

To understand the evolution of GII.P6-GII.6 and GII.P7-GII.6 strains, the prevalent human norovirus genotypes, we analysed both the RdRp region and VP1 gene in globally collected strains using authentic bioinformatics technologies. A common ancestor of the P6- and P7-type RdRp region emerged approximately 50 years ago and a common ancestor of the P6- and P7-type VP1 gene emerged approximately 110 years ago. Subsequently, the RdRp region and VP1 gene evolved. Moreover, the evolutionary rates were significantly faster for the P6-type RdRp region and VP1 gene than for the P7-type RdRp region and VP1 genes. Large genetic divergence was observed in the P7-type RdRp region and VP1 gene compared with the P6-type RdRp region and VP1 gene. The phylodynamics of the RdRp region and VP1 gene fluctuated after the year 2000. Positive selection sites in VP1 proteins were located in the antigenicity-related protruding 2 domain, and these sites overlapped with conformational epitopes. These results suggest that the GII.6 VP1 gene and VP1 proteins evolved uniquely due to recombination between the P6- and P7-type RdRp regions in the HuNoV GII.P6-GII.6 and GII.P7-GII.6 virus strains.

Molecular evolutionary analyses of the fusion protein gene in human respirovirus 1.

Few evolutionary studies of the human respiratory virus (HRV) have been conducted, but most of them have focused on HRV3. In this study, the full-length fusion (F) genes in HRV1 strains collected from various countries were subjected to time-scaled phylogenetic, genome population size, and selective pressure analyses. Antigenicity analysis was performed on the F protein. The time-scaled phylogenetic tree using the Bayesian Markov Chain Monte Carlo method estimated that the common ancestor of the HRV1 F gene diverged in 1957 and eventually formed three lineages. Phylodynamic analyses showed that the genome population size of the F gene has doubled over approximately 80 years. Phylogenetic distances between the strains were short (< 0.02). No positive selection sites were detected for the F protein, whereas many negative selection sites were identified. Almost all conformational epitopes of the F protein, except one in each monomer, did not correspond to the neutralising antibody (NT-Ab) binding sites. These results suggest that the HRV1 F gene has constantly evolved over many years, infecting humans, while the gene may be relatively conserved. Mismatches between computationally predicted epitopes and NT-Ab binding sites may be partially responsible for HRV1 reinfection and other viruses such as HRV3 and respiratory syncytial virus.

Immune checkpoint inhibitor-related haemophagocytic lymphohistiocytosis in a patient with non-small cell lung carcinoma.

Hemophagocytic lymphohistiocytosis (HLH) has been reported as a rare complication of immune checkpoint inhibitors (ICI); however, ICI-related HLH is a life-threatening and comparatively late adverse event. Early diagnosis is critical, and it should be included in the differential diagnosis especially in patients with cytopenia with fever and hyperferritinaemia.

Molecular Evolutionary Analyses of the Pseudomonas-Derived Cephalosporinase Gene.

Despite the increasing evidence of the clinical impact of Pseudomonas-derived cephalosporinase (PDC) sequence polymorphisms, the molecular evolution of its encoding gene, blaPDC, remains elusive. To elucidate this, we performed a comprehensive evolutionary analysis of blaPDC. A Bayesian Markov Chain Monte Carlo phylogenetic tree revealed that a common ancestor of blaPDC diverged approximately 4660 years ago, leading to the formation of eight clonal variants (clusters A-H). The phylogenetic distances within clusters A to G were short, whereas those within cluster H were relatively long. Two positive selection sites and many negative selection sites were estimated. Two PDC active sites overlapped with negative selection sites. In docking simulation models based on samples selected from clusters A and H, piperacillin was bound to the serine and the threonine residues of the PDC active sites, with the same binding mode for both models. These results suggest that, in P. aeruginosa, blaPDC is highly conserved, and PDC exhibits similar antibiotic resistance functionality regardless of its genotype.

Rhinovirus Infection and Virus-Induced Asthma.

While the aetiology of asthma is unclear, the onset and/or exacerbation of asthma may be associated with respiratory infections. Virus-induced asthma is also known as virus-associated/triggered asthma, and the reported main causative agent is rhinovirus (RV). Understanding the relationship between viral infections and asthma may overcome the gaps in deferential immunity between viral infections and allergies. Moreover, understanding the complicated cytokine networks involved in RV infection may be necessary. Therefore, the complexity of RV-induced asthma is not only owing to the response of airway and immune cells against viral infection, but also to allergic immune responses caused by the wide variety of cytokines produced by these cells. To better understand RV-induced asthma, it is necessary to elucidate the nature RV infections and the corresponding host defence mechanisms. In this review, we attempt to organise the complexity of RV-induced asthma to make it easily understandable for readers.

Detailed Molecular Interactions between Respiratory Syncytial Virus Fusion Protein and the TLR4/MD-2 Complex In Silico.

Molecular interactions between respiratory syncytial virus (RSV) fusion protein (F protein) and the cellular receptor Toll-like receptor 4 (TLR4) and myeloid differentiation factor-2 (MD-2) protein complex are unknown. Thus, to reveal the detailed molecular interactions between them, in silico analyses were performed using various bioinformatics techniques. The present simulation data showed that the neutralizing antibody (NT-Ab) binding sites in both prefusion and postfusion proteins at sites II and IV were involved in the interactions between them and the TLR4 molecule. Moreover, the binding affinity between postfusion proteins and the TLR4/MD-2 complex was higher than that between prefusion proteins and the TLR4/MD-2 complex. This increased binding affinity due to conformational changes in the F protein may be able to form syncytium in RSV-infected cells. These results may contribute to better understand the infectivity and pathogenicity (syncytium formation) of RSV.

Impact of COVID-19 Countermeasures on Pediatric Infections.

(1) Background: General infection control measures have been implemented at the societal level against COVID-19 since the middle of 2020, namely, hand hygiene, universal masking, and social distancing. The suppressive effect of the social implementation of general infection control measures on pediatric infections has not been systematically assessed. (2) Methods: We addressed this issue based on publicly available data on 11 pediatric infections reported weekly by sentinel sites in Osaka and Iwate prefectures in Japan since 2010. We obtained the 5-year average for 2015-2019 and compared it to the weekly report for 2020-2021. (3) Results: The rate of 6 of the 11 pediatric infections decreased significantly during 2020-2021, regardless of the magnitude of the prevalence of COVID-19 in both areas. However, only RSV infection, one of the six infections, was endemic in 2021. Exanthem subitum was not as affected by COVID-19 countermeasures as other diseases. (4) Conclusions: The social implementation of infectious disease control measures was effective in controling certain infectious diseases in younger age groups, where compliance with the countermeasures should not be as high as that of adults.

Molecular Evolution of the Pseudomonas aeruginosa DNA Gyrase gyrA Gene.

DNA gyrase plays important roles in genome replication in various bacteria, including Pseudomonasaeruginosa. The gyrA gene encodes the gyrase subunit A protein (GyrA). Mutations in GyrA are associated with resistance to quinolone-based antibiotics. We performed a detailed molecular evolutionary analyses of the gyrA gene and associated resistance to the quinolone drug, ciprofloxacin, using bioinformatics techniques. We produced an evolutionary phylogenetic tree using the Bayesian Markov Chain Monte Carlo (MCMC) method. This tree indicated that a common ancestor of the gene was present over 760 years ago, and the offspring formed multiple clusters. Quinolone drug-resistance-associated amino-acid substitutions in GyrA, including T83I and D87N, emerged after the drug was used clinically. These substitutions appeared to be positive selection sites. The molecular affinity between ciprofloxacin and the GyrA protein containing T83I and/or D87N decreased significantly compared to that between the drug and GyrA protein, with no substitutions. The rate of evolution of the gene before quinolone drugs were first used in the clinic, in 1962, was significantly lower than that after the drug was used. These results suggest that the gyrA gene evolved to permit the bacterium to overcome quinolone treatment.

Detailed Analyses of Molecular Interactions between Favipiravir and RNA Viruses In Silico.

There are currently no antiviral agents for human metapneumovirus (HMPV), respiratory syncytial virus (RSV), mumps virus (MuV), or measles virus (MeV). Favipiravir has been developed as an anti-influenza agent, and this agent may be effective against these viruses in vitro. However, the molecular mechanisms through which the agent affects virus replication remain to be fully elucidated. Thus, to clarify the detailed molecular interactions between favipiravir and the RNA-dependent RNA polymerase (RdRp) of HMPV, RSV, MuV, MeV, and influenza virus, we performed in silico studies using authentic bioinformatics technologies. As a result, we found that the active form of favipiravir (favipiravir ribofuranosyl-5'-triphosphate [F-RTP]) can bind to the RdRp active sites of HMPV, RSV, MuV, and MeV. The aspartic acid residue of RdRp active sites was involved in the interaction. Moreover, F-RTP was incorporated into the growing viral RNA chain in the presence of nucleotide triphosphate and magnesium ions. The results suggested that favipiravir shows two distinct mechanisms in various viruses: RdRp active site inhibition and/or genome replication inhibition.

Detailed Evolutionary Analyses of the F Gene in the Respiratory Syncytial Virus Subgroup A.

We performed evolution, phylodynamics, and reinfection-related antigenicity analyses of respiratory syncytial virus subgroup A (RSV-A) fusion (F) gene in globally collected strains (1465 strains) using authentic bioinformatics methods. The time-scaled evolutionary tree using the Bayesian Markov chain Monte Carlo method estimated that a common ancestor of the RSV-A, RSV-B, and bovine-RSV diverged at around 450 years ago, and RSV-A and RSV-B diverged around 250 years ago. Finally, the RSV-A F gene formed eight genotypes (GA1-GA7 and NA1) over the last 80 years. Phylodynamics of RSV-A F gene, including all genotype strains, increased twice in the 1990s and 2010s, while patterns of each RSV-A genotype were different. Phylogenetic distance analysis suggested that the genetic distances of the strains were relatively short (less than 0.05). No positive selection sites were estimated, while many negative selection sites were found. Moreover, the F protein 3D structure mapping and conformational epitope analysis implied that the conformational epitopes did not correspond to the neutralizing antibody binding sites of the F protein. These results suggested that the RSV-A F gene is relatively conserved, and mismatches between conformational epitopes and neutralizing antibody binding sites of the F protein are responsible for the virus reinfection.

Research Activities in Materials Science and Engineering with Academic-Industrial Alliances during the COVID-19 Pandemic.

During the COVID 19 pandemic, the importance of global academia-industrial alliances has increased. It is hoped that the alliances will help us to solve the current problems caused by the pandemic. In this paper, we introduce the application of IT tools and communication skills utilized in a special educational project for an academia-industrial collaboration. Some concrete examples from 2020 are provided from the viewpoint of the national alliance project in Japan. A discussion is included that describes the plans available to increase and strengthen the national project in the future.

Clinical risk factors related to treatment failure in Mycobacterium abscessus lung disease.

The clinical importance of Mycobacterium abscessus subsp. abscessus (M. abscessus) lung disease has been increasing, but few studies have assessed the clinical characteristics associated with the treatment outcome. We retrospectively analyzed 75 consecutive patients with M. abscessus lung disease diagnosed at a tertiary hospital from January 2004 to April 2018. Among 52 patients with sufficient clinical data, 19 patients (42.2%) achieved treatment success. Compared with 26 (57.8%) patients in the treatment failure group, body mass index (BMI) (19.8 vs 17.5 kg/m2, P = 0.022), previous nontuberculous mycobacterial (NTM) lung disease (26.3% vs 61.5%, P = 0.034), the presence of cavitary lesions (31.6% vs 69.2%, P = 0.017), and the bronchiectasis score (3.0 vs 5.0, P = 0.003) were significantly different in the treatment success group. Multivariate analysis showed that age (adjusted hazard ratio (aHR), 0.94; 95% confidence interval (CI), 0.90 to 0.99; P = 0.010), the presence of cavitary lesions (aHR, 0.34; 95% CI, 0.12 to 0.94; P = 0.039), and previous NTM lung disease (aHR, 0.28; 95% CI, 0.09 to 0.86; P = 0.026) were negatively associated with treatment success. This is the first study to show that previous NTM lung disease might be a clinically important factor related to unfavorable treatment outcomes in M. abscessus lung disease patients. To increase our understanding the characteristics of M. abscessus lung disease, this factor should be independently analyzed in future research.

Novel predictive factors for patient discomfort and severe cough during bronchoscopy: A prospective questionnaire analysis.

During bronchoscopy, discomfort is mainly caused by an unavoidable cough; however, there are no reports of any predictive factors for strong cough during bronchoscopy identified before the procedure. To clarify the factors underlying the discomfort status and predictive factors for strong cough during bronchoscopy, we prospectively evaluated patients who underwent bronchoscopy at Kyorin University Hospital between March 2018 and July 2019. Before and after bronchoscopy, the enrolled patients answered a questionnaire regarding the procedure. At the same time, bronchoscopists evaluated cough severity using a four-grade cough scale. We evaluated patient characteristics and predictive factors associated with bronchoscopy from the perspective of discomfort and strong cough. A total of 172 patients were ultimately enrolled in this study. On multivariate logistic regression analysis, comparison of the subjective data between the discomfort and comfort groups revealed that factors that were more common in the former group were younger age (OR = 0.96, p = 0.002), less experienced bronchoscopist (OR = 2.08, p = 0.047), and elevation of cough score per 1 point (OR = 1.69, p < 0.001). Furthermore, the predictive factors for strong cough prior to performing bronchoscopy were female sex (OR = 2.57, p = 0.009), EBUS-TBNA (OR = 2.95, p = 0.004), and prolonged examination time of more than 36 min (OR = 2.32, p = 0.022). Regarding patients' discomfort, younger age, less experienced bronchoscopist, and the elevation of cough score per 1 point were important factors for discomfort in bronchoscopy. On the other hand, female sex, EBUS-TBNA, and prolonged examination time were crucial factors for strong cough.

Impact of Aspergillus precipitating antibody test results on clinical outcomes of patients with Mycobacterium avium complex lung disease.

BACKGROUND AND OBJECTIVE: Chronic pulmonary aspergillosis (CPA) is associated with mortality in patients with Mycobacterium avium complex lung disease (MAC-LD). However, the clinical significance of the positivity of Aspergillus precipitating antibody (APAb), a serodiagnostic test for pulmonary aspergillosis (PA), at the time of MAC-LD diagnosis is unknown. The objective of this study was to investigate the effects of APAb test results on the clinical outcomes of patients with MAC-LD. METHODS: We retrospectively analyzed patients who were newly diagnosed as having MAC-LD between 2007 and 2014 in our hospital and checked for APAb at the time of diagnosis. RESULTS: We enrolled 131 patients in this study. Of these patients, 20 (15.3%) tested positive for APAb at the diagnosis of MAC-LD. The APAb-positive patients were more frequently male (70.0% vs. 37.8%, P = 0.013) and more frequently had pulmonary emphysema (60.0% vs. 13.5%, P < 0.001) and interstitial pneumonia (15.0% vs. 1.8%, P = 0.025) compared with the APAb-negative patients. During a median follow-up period of 4.0 years, PA developed in 12 of the APAb-positive patients (60.0%, CPA: 9 and allergic bronchopulmonary aspergillosis: 3) and 12 APAb-negative patients (10.8%, CPA: 12) (P < 0.001). The APAb-positive patients had a significantly higher rate of mortality than did the APAb-negative patients (P = 0.004). A multivariate analysis indicated that older age, lower albumin, fibrocavitary or fibrocavitary and nodular/bronchiectatic radiographic features, and APAb positivity were negative prognostic factors. CONCLUSIONS: APAb-positive patients with MAC-LD more frequently develop PA and may have an unfavorable prognosis.