Nontuberculous mycobacterial pulmonary disease presenting as bronchiolitis pattern on CT without cavity or bronchiectasis.

BACKGROUND: This study aimed to investigate the radiological changes in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) having bronchiolitis patterns on computed tomography (CT). METHODS: We retrospectively reviewed the final diagnosis and radiologic changes of patients suspected of having NTM-PD without cavity or bronchiectasis on CT image, between January 1, 2005 and March 31, 2021. NTM-PD was diagnosed based on the American Thoracic Society and Infectious Diseases Society of America criteria. The initial and final CT findings (bronchiectasis, cellular bronchiolitis, cavity formation, nodules, and consolidation) were compared between patients diagnosed with and without NTM-PD. RESULTS: This study included 96 patients and 515 CT images. The median CT follow-up duration was 1510.5 (interquartile range: 862.2-3005) days. NTM-PD was recognized in 43 patients. The clinical variables were not significantly different between patients with and without NTM-PD, except for underlying chronic airway disease (P < 0.001). Nodule and consolidation were more frequently observed on the initial CT scans of patients with NTM-PD compared with those without (P < 0.05). On the final follow-up CT scan, bronchiectasis (P < 0.001), cavity (P < 0.05), nodule (P < 0.05), and consolidation (P < 0.05) were more frequently observed in patients with NTM-PD. Among the 43 patients with NTM-PD, 30 showed a radiological progression on CT, with bronchiectasis (n = 22) being the most common finding. The incidence of bronchiectasis increased over time. CONCLUSION: The bronchiolitis pattern on CT images of patients with NTM-PD showed frequent radiological progression during the follow-up period.

Tuberculosis and Nontuberculous Mycobacterial Infections in Patients with Spondyloarthritis: A Population-Based Study.

Background and Objectives: Tuberculosis is caused by Mycobacterium tuberculosis (MTB), while nontuberculous mycobacteria (NTM) encompass a group of mycobacterial species that are distinct from the MTB complex and leprae. Spondyloarthritis (SpA) is a group of chronic inflammatory diseases with shared clinical characteristics and is treated with biological agents; however, their use may elevate the risk of MTB and NTM infections. This study aimed to compare the incidence and risk of MTB and NTM infections in patients with SpA, including ankylosing spondylitis (AS) and psoriatic arthritis (PsA), using a population-based approach. Materials and Methods: This study included 2333 patients with SpA and 9332 age- and sex-matched controls from the Korea National Health Insurance Service-National Sample Cohort database from 2002 to 2019. The patients were identified using the International Classification of Diseases-10 codes for AS, PsA, MTB, and NTM. Results: The results showed that a negligible percentage of patients with SpA developed NTM (0.002%) and MTB (0.016%), with no significant difference in the incidence rate ratio (IRR) compared to controls. Among patients with SpA treated with biologics, the IRRs for NTM and MTB were 5.66 and 3.069, respectively; however, these were not statistically significant. No cases of NTM or MTB infection were reported in female patients with SpA treated with biologics. In both the SpA patient group and the control group, the incidence of MTB was higher in individuals over 60 years old compared to those under 60 years old. Cox proportional hazard analysis revealed a significant adjusted hazard ratio of 1.479 for MTB in patients with SpA after adjusting for age, sex, smoking history, insurance level, and comorbidities. However, this significance was not maintained when biological therapy was further adjusted. Conclusions: Our study indicated that the risks of NTM and MTB infection are not elevated in patients with SpA. Although biological use may potentially increase the risk of MTB infection, it does not lead to a significant increase in incidence rates. Proactive screening for latent tuberculosis and adequate prophylaxis using biologics can effectively manage the risk of NTM and MTB infections.

Treatment of Nontuberculous Mycobacterial (NTM) Pulmonary Infection in the US Bronchiectasis and NTM Registry: Treatment Patterns, Adverse Events, and Adherence to American Thoracic Society/Infectious Disease Society of America Treatment Guidelines.

Among 1038 participants with pulmonary Mycobacterium avium complex and 120 with Mycobacterium abscessus enrolled in the US Bronchiectasis and NTM Research Registry, less than half received antibiotic therapy in the 24 months before registry enrollment, of which less than half were guideline based. Adverse effects occurred in 21% of therapy recipients, of whom 33% discontinued therapy.

CXCL9 as a Reliable Biomarker for Discriminating Anti-IFN-γ-Autoantibody-Associated Lymphadenopathy that Mimics Lymphoma.

The diagnosis of adult-onset immunodeficiency syndrome associated with neutralizing anti-interferon γ autoantibodies (AIGA) presents substantial challenges to clinicians and pathologists due to its nonspecific clinical presentation, absence of routine laboratory tests, and resemblance to certain lymphoma types, notably nodal T follicular helper cell lymphoma, angioimmunoblastic type (nTFHL-AI). Some patients undergo lymphadenectomy for histopathological examination to rule out lymphoma, even in the absence of a preceding clinical suspicion of AIGA. This study aimed to identify reliable methods to prevent misdiagnosis of AIGA in this scenario through a retrospective case-control analysis of clinical and pathological data, along with immune gene transcriptomes using the NanoString nCounter platform, to compare AIGA and nTFHL-AI. The investigation revealed a downregulation of the C-X-C motif chemokine ligand 9 (CXCL9) gene in AIGA, prompting an exploration of its diagnostic utility. Immunohistochemistry (IHC) targeting CXCL9 was performed on lymph node specimens to assess its potential as a diagnostic biomarker. The findings exhibited a significantly lower density of CXCL9-positive cells in AIGA compared to nTFHL-AI, displaying a high diagnostic accuracy of 92.3% sensitivity and 100% specificity. Furthermore, CXCL9 IHC demonstrated its ability to differentiate AIGA from various lymphomas sharing similar characteristics. In conclusion, CXCL9 IHC emerges as a robust biomarker for differentiating AIGA from nTFHL-AI and other similar conditions. This reliable diagnostic approach holds the potential to avert misdiagnosis of AIGA as lymphoma, providing timely and accurate diagnosis.

A case of mediastinal abscess and infected aortic aneurysm caused by dissemination of Mycobacterium abscessus subsp. massiliense pulmonary disease.

An 81-year-old man was admitted to our hospital because of fever and malaise that had persisted for 3 months. The patient had undergone two aortic valve replacements, 10 and 5 years previously, because of aortic valve regurgitation and infectious endocarditis. He also had had asymptomatic Mycobacterium abscessus complex (MABC) pulmonary disease for the two previous years. Contrast-enhanced computed tomography showed a mediastinal abscess and an ascending aortic aneurysm. Mycobacterium abscessus subsp. massiliense was cultured from his blood, suggesting the aortic aneurysm was secondary to infection of an implanted device. After enlargement over only a few days, a leakage of contrast medium to the mediastinal abscess was found on computed tomography. The patient was diagnosed with rupture of an infectious aortic aneurysm, and emergency aortic replacement and drainage of the mediastinal abscess were successful. The patient was treated with several antibiotics, including meropenem, amikacin, and clarithromycin, and his general condition improved. Cultures from both the mediastinal abscess and a pericardial patch that was placed at the time of surgery 5 years previously revealed MABC. In our case, the infected aortic aneurysm most likely resulted from MABC pulmonary disease rather than from previous intraoperative contamination. This route of infection is rare. Physicians should be aware of the possibility of dissemination and subsequent infection of implants related to MABC pulmonary disease.

Validity of Diagnosis Code-Based Claims to Identify Pulmonary NTM Disease in Bronchiectasis Patients.

Nontuberculous mycobacteria infection is increasing in incidence and can lead to chronic, debilitating pulmonary disease. We investigated the accuracy of diagnosis code-based nontuberculous mycobacteria lung disease claims among Medicare beneficiaries in the United States. We observed that these claims have moderate validity, but given their low sensitivity, incidence might be underestimated.

Subcutaneous injection of interferon gamma therapy could be useful for anti-IFN-γ autoantibody associated disseminated nontuberculous mycobacterial infection.

One of the human natural defense systems protects against nontuberculous mycobacterial (NTM) infection by IFN-γ producing T lymphocyte cells. Most disseminated NTM infections usually occur in severe immune-compromised patients, such as HIV infection or after organ transplant patients. However, there have been several reports of non-compromised patients with disseminated NTM infection, including antibiotic resistance cases and the presence of a neutralizing antibody against IFN-γ. We elucidated the anti-IFN-γ neutralizing antibody in a 65 year-old Japanese man whose legs were paralyzed because of multiple abscesses in vertebral bodies. Although his vertebral bodies were released due to an operation and antibiotics were administered, this treatment efficacy was poor. Patient's plasma demanded not only IFN-γ expression in peripheral blood mononuclear cells (PBMC) obtained from healthy controls, but also recombinant human IFN-γ expression. Furthermore, IFN-γ receptor expression was increased, compared to the healthy control. Finally, anti-IFN-γ antibody was detected in his plasma. These results suggested that anti-IFN-γ antibody induced an incurable NTM infection. IFN-γ was subcutaneously administrated with antibiotics, and then the abscesses diminished and his general condition was successfully improved. This therapy might be useful against severe NTM infections.

Incidence of ocular inflammation among patients with active tuberculosis or nontuberculous mycobacterial infections in a tertiary hospital in Japan.

PURPOSE: This study aimed to elucidate the incidence of ocular involvement among patients with active tuberculosis (TB) or nontuberculous mycobacterial (NTM) infection in a hospital in Japan. METHODS: Patients with active TB or NTM infection at Yoshijima Hospital from April 2017 to July 2018 were included in this retrospective study. All patients underwent ophthalmic examinations, including fundus evaluation under pupil dilation, before initiation of antibiotic therapy. Patients with ocular inflammation were regularly followed up by ophthalmologists. RESULTS: In total, 101 patients with active TB and 27 patients with active NTM infection underwent ophthalmic examinations during the study period. Seven patients with TB (6.9%) had ocular inflammation; four had bilateral involvement. In these seven patients, ocular inflammation comprised anterior uveitis (n = 2), intermediate uveitis (n = 1), posterior uveitis (n = 4). Choroidal tubercles were observed in two patients with posterior uveitis. Female sex was associated with higher incidence of ocular inflammation among patients with TB. Conversely, no patients with NTM infection had ocular inflammation. CONCLUSION: Ocular inflammation was present in approximately 7% of patients with active TB. Although TB choroiditis is presumed to be rare in Japan, approximately 30% of the patients with ocular inflammation exhibited choroidal lesions in this study. In contrast, no ocular inflammation was observed among patients with systemic NTM infection.

Natural History and Evolution of Anti-Interferon-γ Autoantibody-Associated Immunodeficiency Syndrome in Thailand and the United States.

BACKGROUND: The natural history of anti-interferon-γ (IFN-γ) autoantibody-associated immunodeficiency syndrome is not well understood. METHODS: Data of 74 patients with anti-IFN-γ autoantibodies at Srinagarind Hospital, Thailand, were collected annually (median follow-up duration, 7.5 years). Annual data for 19 patients and initial data for 4 patients with anti-IFN-γ autoantibodies at the US National Institutes of Health were collected (median follow-up duration, 4.5 years). Anti-IFN-γ autoantibody levels were measured in plasma samples. RESULTS: Ninety-one percent of US patients were of Southeast Asian descent; there was a stronger female predominance (91%) in US than Thai (64%) patients. Mycobacterium abscessus (34%) and Mycobacterium avium complex (83%) were the most common nontuberculous mycobacteria in Thailand and the United States, respectively. Skin infections were more common in Thailand (P = .001), whereas bone (P < .0001), lung (P = .002), and central nervous system (P = .03) infections were more common in the United States. Twenty-four percent of Thai patients died, most from infections. None of the 19 US patients with follow-up data died. Anti-IFN-γ autoantibody levels decreased over time in Thailand (P < .001) and the United States (P = .017), with either cyclophosphamide (P = .01) or rituximab therapy (P = .001). CONCLUSIONS: Patients with anti-IFN-γ autoantibodies in Thailand and the United States had distinct demographic and clinical features. While titers generally decreased with time, anti-IFN-γ autoantibody disease had a chronic clinical course with persistent infections and death. Close long-term surveillance for new infections is recommended.

Disseminated Mycobacterium abscessus subsp. massiliense infection in a Good's syndrome patient negative for human immunodeficiency virus and anti-interferon-γ autoantibody: a case report.

BACKGROUND: Good's syndrome (GS) is characterized by immunodeficiency, and can lead to severe infection, which is the most significant complication. Although Mycobacterium rarely causes infection in patients with GS, disseminated nontuberculous mycobacterial (NTM) infection frequently occurs in GS patients that are also positive for the human immunodeficiency virus (HIV) or anti-interferon (IFN)-γ autoantibodies. Here, we report a rare case of GS with NTM without HIV or IFN-γ autoantibodies. CASE PRESENTATION: A 57-year-old Japanese male with GS and myasthenia gravis (treated with prednisolone and tacrolimus) was diagnosed with disseminated NTM infection caused by Mycobacterium abscessus subsp. massiliense. He presented with fever and back pain. Blood, lumbar tissue, urine, stool, and sputum cultures tested positive for M. abscessus. Bacteremia, spondylitis, intestinal lumber abscess, and lung infection were confirmed by bacteriological examination and diagnostic imaging; urinary and intestinal tract infections were suspected by bacteriological examination but not confirmed by imaging. Despite multidrug combination therapy, including azithromycin, imipenem/cilastatin, levofloxacin, minocycline, linezolid, and sitafloxacin, the patient ultimately died of the infection. The patient tested negative for HIV and anti-IFN-γ autoantibodies. CONCLUSIONS: Since myasthenia gravis symptoms interfere with therapy, patients with GS and their physicians should carefully consider the antibacterial treatment options against disseminated NTM.

Progressive disseminated histoplasmosis with concomitant disseminated nontuberculous mycobacterial infection in a patient with AIDS from a nonendemic region (California).

BACKGROUND: Opportunistic infections, while well studied in the AIDS population, continue to have variable and surprising presentations. Here, we present a case of disseminated histoplasmosis with disseminated nontuberculous mycobacterial infection in a 50 year old man with long standing AIDS living in a non-endemic area. CASE PRESENTATION: Patient presented with a constellation of symptoms, and imaging of the chest showed a pulmonary mass with cavitation, multiple nodules, and ground glass opacities. Further investigations revealed granulomatous lung nodules and fungemia consistent with Histoplasma capsulatum, and coinfection with disseminated nontuberculous mycobateria in a nonendemic area. CONCLUSIONS: Immunocompromised patients risk co-inhabitation by multiple infectious organisms. Some of these organisms may preside in the host for years prior to reactivation. Clinicians in non endemic areas should therefore be careful to not overlook specific organisms based on a lack of a recent travel history. Physicians in nonendemic areas should become more familiar with the clinical findings and diagnostic approach of infectious such as Histoplasmosis, to ensure earlier recognition and treatment in immunocompromised individuals.

Specificity of QuantiFERON-TB Plus, a New-Generation Interferon Gamma Release Assay.

Interferon gamma release assays (IGRAs) are important tools in identifying prior tuberculosis exposure. The new-generation QuantiFERON-TB Gold Plus (QFT-Plus) assay, recently approved for use in the United States, differs from the current-generation QFT Gold-In-Tube (QFT-GIT) assay with the addition of a second antigen tube that also contains novel CD8+ T-cell-stimulating peptides. The QFT-Plus assay has increased sensitivity in immunocompromised populations, and we sought to assess the specificity of QFT-Plus compared to that of QFT-GIT in low-risk individuals. We enrolled adults without tuberculosis risk factors, including a subgroup with pulmonary nontuberculous mycobacterial (NTM) disease due to Mycobacterium avium complex (MAC) or Mycobacterium abscessus. The primary outcome measures included specificity, interassay concordance, and agreement between the QFT-Plus and QFT-GIT assays. Of 262 participants enrolled, 51 had pulmonary NTM. The median age was 39 years (age range, 18 to 78 years); 73% were female. Among the 262 individuals who were enrolled, 5 (1.9%) individuals had positive QFT-Plus results, and 3 of these individuals also had positive QFT-GIT results. The two individuals with discordant results (QFT-Plus positive/QFT-GIT negative) had only one tube positive in the QFT-Plus assay. The overall specificity of QFT-Plus and QFT-GIT was 98.1% (95% confidence interval [CI], 95.6, 99.4%) and 98.9% (95% CI, 96.7, 99.8%), respectively. The QFT-Plus specificity was similar in both the NTM (98.0% [95% CI, 89.4, 99.9%]) and non-NTM (98.1% [95% CI, 95.2, 99.5%]) groups. QFT-Plus has a high specificity, similar to that of the QFT-GIT assay, including in patients with pulmonary MAC or M. abscessus disease.

Successful management of Mycobacterium haemophilum lower extremity cutaneous infection in a matched-unrelated donor stem cell transplant recipient.

Nontuberculous mycobacterial infections can often occur in individuals with adequate immune function. Such infections typically have cutaneous involvement and are caused by rapidly growing mycobacterium. Other nontuberculous mycobacteria species, like Mycobacterium haemophilum, almost always present as opportunistic infections occurring in severely immunocompromised hosts. Here, we present a complicated and protracted course of diagnosing M. haemophilum lower extremity cutaneous infection in a matched-unrelated donor stem cell transplant recipient.

Disseminated Nontuberculous Mycobacterial Infection in a Patient with Anti-IFN-γ Autoantibodies.

We treated a 72-year-old Japanese female with sustained high fever and overall body exhaustion. An infectious liver cyst and right lung pneumonia were suspected causes. Hepatic cystectomy and various antibiotics did not resolve symptoms. Pneumonia exacerbation and ascitic fluid retention, left lumbar spinal osteomyelitis, and peri-gastric lymph node abscess penetrating the stomach were observed. Mycobacterium avium was identified in sputum, ascites, vertebral body abscess puncture specimen, and pus mucus secretion in the stomach. We diagnosed a disseminated nontuberculous mycobacterial infection. She seemed immunocompetent, without signs of AIDS or hematological malignancy. Serum anti-IFN-γ autoantibodies tested positive and were suspected to be involved in the illness onset.

Impact of pulmonary nontuberculous mycobacterial treatment on pulmonary function tests in patients with and without established obstructive lung disease.

BACKGROUND AND OBJECTIVE: There is relatively little data regarding pulmonary function test (PFT) findings and impact of treatment on PFT in pulmonary nontuberculous mycobacterial (pNTM) disease. METHODS: We performed a retrospective study on pNTM patients. Clinical, radiographical, microbiological and PFT data were reviewed. Patients were divided into three groups based on pre-existing obstructive lung disease: (i) normal (no chronic obstructive pulmonary disease (COPD) or asthma); (ii) asthma; and (iii) COPD. We studied pre-treatment PFT and assessed for PFT changes after anti-mycobacterial therapy. RESULTS: A total of 96 patients fulfilled ATS disease criteria and had pre-treatment PFT (54 'normal', 18 asthma, 24 COPD). Most common causative NTM was Mycobacterium avium complex (76%), and radiographical disease type was nodular bronchiectasis (71%). Before therapy, all groups had PFT abnormalities, including obstruction, gas trapping and at least mildly low diffusion capacity of carbon monoxide (DLCO). Pre-treatment PFT abnormalities were more pronounced among patients with asthma and COPD. A total of 44 patients had >12 months anti-mycobacterial therapy and post-treatment PFT. There tended to be small and generally not statistically significant reductions in spirometry and DLCO in most groups. Among the nine asthmatic patients, there was a small reduction in residual volume (RV) (1.5% predicted, P = 0.01) and RV/total lung capacity (by 7% predicted, P = 0.06). CONCLUSIONS: Patients with pNTM have abnormal PFT, and treatment was not associated with substantial changes therein. Asthmatics may experience some improvements in gas trapping after NTM therapy, but because the sample size and the observed change were both small, this requires further investigation.

Possible role of anaerobes in the pathogenesis of nontuberculous mycobacterial infection.

BACKGROUND AND OBJECTIVE: Recent advances in cultivation-independent molecular biological modalities for detecting bacterial species have indicated that several bacterial species may play a role in the pathogenesis of certain infectious diseases. The aim of this study was to evaluate the role of bacterial flora in the pathogenesis of nontuberculous mycobacteriosis (NTM) using a bacterial floral analysis of bronchoalveolar lavage fluid (BALF) with 16S rRNA gene sequencing in patients with bronchiectasis. METHODS: Fifty-eight patients with bronchiectasis evaluated using chest computed tomography were enrolled. BALF obtained from the most affected lung lesions was evaluated using culture and culture-independent methodologies. Approximately 600 bp of the bacterial 16S rRNA gene (E341F-E907R) was amplified via polymerase chain reaction using universal primers, and clone libraries were constructed. Nucleotide sequences of 96 randomly chosen clones for each specimen were determined, and the homology was searched using a basic local alignment search tool to determine the bacterial phylotypes and their proportions (bacterial floral analysis) in each specimen. RESULTS: Twenty-nine patients with bronchiectasis were diagnosed with NTM based on culture-based methods using Ogawa medium. The molecular method showed a significantly high rate of anaerobes among the patients with NTM compared with that observed in the bronchiectasis patients without NTM. In addition, findings of collapse/consolidation were significantly related to the proportion of Prevotella species in the BALF samples determined using the molecular method (P < 0.001). CONCLUSION: Given the results of the present study, anaerobes may play an important role in the pathogenesis of bronchiectasis in patients with NTM.

Subcutaneous infection caused by Mycobacterium abscessus following botulinum toxin injections: A case report and literature review.

BACKGROUND: The rapid development of cosmetic injections has led to an increased incidence of nontuberculous mycobacterial (NTM) infection. PATIENTS AND METHODS: Here, we presented a case of cutaneous Mycobacterium abscessus infection subsequent to botulinum toxin injection for treating masseter hypertrophy, and reviewed the literature on skin and soft tissue infections caused by NTM after cosmetic injections. RESULTS AND CONCLUSIONS: The patient underwent surgical excision and regular antibiotic therapy and has had nearly 2 months of follow-up without any signs of infection. The diagnosis and treatment of NTM infection have always been challenging, and further research is needed to standardize and guide the treatment.

Clinical Characteristics and Outcomes of Extrapulmonary Nontuberculous Mycobacterial Infections in a Tertiary-Care Hospital: A Retrospective Study.

Background/Objectives: The incidence of nontuberculous mycobacterial (NTM) infections has increased globally; however, the clinical manifestations and optimal treatment strategies for extrapulmonary NTM infections remain poorly defined. This study assessed the clinical manifestations and treatment outcomes of extrapulmonary NTM infections. Methods: Data from adult patients with suspected extrapulmonary NTM infections at a tertiary-care hospital from 2009-2022 were categorized into NTM disease and isolation groups. Diagnosis of NTM disease relied on stringent criteria, whereas isolation required NTM isolation without meeting the criteria for infection. Results: Among 75 patients evaluated, 32 (42%) were diagnosed with NTM disease and 43 (57%) with NTM isolation. History of immunosuppressant use within the past 3 months (p = 0.070) and injection (p = 0.001) were more frequent in the disease group. The median interval from symptom onset to evaluation was 106.6 and 20 days in the disease and isolation groups, respectively. The prevalence of positive NTM polymerase chain reaction results (36.4%, p = 0.003) and acid-fast bacillus staining (39.1%, p < 0.001) was significantly higher in the disease group than in the isolation group. Mycobacterium intracellulare (21.9%), M. abscessus (15.6%), M. chelonae (9.4%), and M. fortuitum complex (9.4%) were the most frequently identified species. Of the 27 patients in the disease group who received treatment, 13 improved, four experienced treatment failure, seven were lost to follow-up, and three died during treatment, with one death directly attributable to NTM disease. Conclusions: NTM disease exhibits a spectrum of clinical manifestations. Accurate diagnosis is crucial for initiating effective treatment.

Pulmonary Mycobacterium avium Complex With Adenocarcinoma of the Lung: A Case Report.

Nontuberculous mycobacteria are responsible for causing pulmonary as well as extrapulmonary diseases. These organisms are often multidrug resistant and management of these cases poses a therapeutic challenge. Lung cancer has been a prevalent challenge globally with a high mortality rate in affected individuals. Adenocarcinoma poses debilitating outcomes in most patients by inflicting a diagnostic and therapeutic challenge. The concomitant association of adenocarcinoma and Mycobacterium avium complex worsens the prognosis causing a challenge in managing such cases. We present a rare association between adenocarcinoma and pulmonary Mycobacterium avium complex complicating the traditional therapeutic regime. A different approach in the administration of therapy for this unique concomitant association between two debilitating diseases is outlined in the presented report.

Nontuberculous mycobacterial infection after fractionated CO(2) laser resurfacing.

Nontuberculous mycobacteria are increasingly associated with cutaneous infections after cosmetic procedures. Fractionated CO2 resurfacing, a widely used technique for photorejuvenation, has been associated with a more favorable side effect profile than alternative procedures. We describe 2 cases of nontuberculous mycobacterial infection after treatment with a fractionated CO2 laser at a private clinic. Densely distributed erythematous papules and pustules developed within the treated area within 2 weeks of the laser procedure. Diagnosis was confirmed by histologic analysis and culture. Both infections responded to a 4-month course of a multidrug regimen. An environmental investigation of the clinic was performed, but no source of infection was found. The case isolates differed from each other and from isolates obtained from the clinic, suggesting that the infection was acquired by postprocedure exposure. Papules and pustules after fractionated CO2 resurfacing should raise the suspicion of nontuberculous mycobacterial infection.