Anti-Interleukin-23 Autoantibodies in Adult-Onset Immunodeficiency

BACKGROUND

Autoantibodies against interleukin-12 (anti-interleukin-12) are often identified in patients with thymoma, but opportunistic infections develop in only some of these patients. Interleukin-12 (with subunits p40 and p35) shares a common subunit with interleukin-23 (subunits p40 and p19). In a patient with disseminated Burkholderia gladioli infection, the identification of both anti-interleukin-23 and anti-interleukin-12 prompted further investigation.

METHODS

Among the patients (most of whom had thymoma) who were known to have anti-interleukin-12, we screened for autoantibodies against interleukin-23 (anti-interleukin-23). To validate the potential role of anti-interleukin-23 with respect to opportunistic infection, we tested a second cohort of patients with thymoma as well as patients without either thymoma or known anti-interleukin-12 who had unusual infections.

RESULTS

Among 30 patients with anti-interleukin-12 who had severe mycobacterial, bacterial, or fungal infections, 15 (50%) also had autoantibodies that neutralized interleukin-23. The potency of such neutralization was correlated with the severity of these infections. The neutralizing activity of anti-interleukin-12 alone was not associated with infection. In the validation cohort of 91 patients with thymoma, the presence of anti-interleukin-23 was associated with infection status in 74 patients (81%). Overall, neutralizing anti-interleukin-23 was detected in 30 of 116 patients (26%) with thymoma and in 30 of 36 patients (83%) with disseminated, cerebral, or pulmonary infections. Anti-interleukin-23 was present in 6 of 32 patients (19%) with severe intracellular infections and in 2 of 16 patients (12%) with unusual intracranial infections, including Cladophialophora bantiana and Mycobacterium avium complex.

CONCLUSIONS

Among patients with a variety of mycobacterial, bacterial, or fungal infections, the presence of neutralizing anti-interleukin-23 was associated with severe, persistent opportunistic infections. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Antimicrobial susceptibility of Mycobacterium abscessus and treatment of pulmonary and extra-pulmonary infections

BACKGROUND

Mycobacterium abscessus (MAB) is the mycobacterial species least susceptible to antimicrobials. Infections are difficult to treat, and cure rates are below 50% even after a combination of 4-5 drugs for many months.

OBJECTIVES

To examine antimicrobial susceptibilities and treatment recommendations in light of what is known about mechanisms of resistance and pharmacodynamics/pharmacokinetics (PK/PD) interactions.

SOURCES

Original papers on the topics of 'antimicrobials', 'susceptibility', 'treatment', and 'outcome' from 2019 onwards, in the context of the evidence brought by the guidelines published in 2020 for pulmonary infections.

CONTENT

MAB is susceptible in vitro to only a few antimicrobials. Breakpoints were set by the Clinical and Laboratory Standards Institute and are revised by the European Committee on Antimicrobial Susceptibility Testing for epidemiological cut-off values. Innate resistance is due to multiple resistance mechanisms involving efflux pumps, inactivating enzymes, and low drug-target affinity. In addition, MAB may display acquired resistance to macrolides and amikacin through mutations in drug binding sites. Treatment outcomes are better for macrolide-based combinations and MAB subspecies massiliense. New compounds in the family of cyclines, oxazolidinones, and penem-β-lactamase inhibitor combinations (described in another paper), as well as bedaquiline, a new antituberculous agent, are promising, but their efficacy remains to be proven. PK/PD studies, which are critical for establishing optimal dosing regimens, were mainly done for monotherapy and healthy individuals.

IMPLICATIONS

Medical evidence is poor, and randomized clinical trials or standardized cohorts are needed to compare outcomes of patients with similar underlying disease, clinical characteristics, and identified MAB subspecies/sequevar. Microbiological diagnosis and susceptibility testing need to be harmonized to enable the comparison of agents and the testing of new compounds. Testing antimicrobial combinations requires new methods, especially for PK/PD parameters. Molecular testing may help in assessing MAB resistance prior to treatment. New antimicrobials need to be systematically tested against MAB to find an effective antimicrobial regimen.

P081 Azole-resistant Aspergillus fumigatus among NIH hospitalized patients with underlying primary immunodeficiencies

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

 

Objectives

Aspergillus fumigatus causes a variety of diseases in humans. The drugs recommended for treatment of Aspergillus diseases are the mold-active azole antifungals. However, a wide range of mutations in A. fumigatus confers azole resistance, which commonly involves modifications in the cyp51Agene, the target for azole antifungal drugs.

Methods

We investigated 255 clinical A. fumigatus isolates obtained from patients hospitalized at National Institutes of Health Clinical Center, Bethesda, Maryland, USA. The species-level identification of each isolate was evaluated by colony morphology, microscopic characteristics, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), and PCR-sequencing of the β-tubulin gene. We also studied sequence-based analysis of the Cyp51A gene for the azole-resistant isolates.

The azole antifungal susceptibility profile of each isolate was initially evaluated using 4-well triazole screen plates (Microbiology Associates LLC, Rockville, MD, USA) containing itraconazole (4 μg/ml), voriconazole (2 μg/ml), posaconazole (0.5 μg/ml), and growth control. The full array of antifungal susceptibility was confirmed using microbroth dilution method according to Clinical and Laboratory Standards Institute CLSI M38-A3 guidelines.

Results

Of 255 A. fumigatus isolates, 12 grew on the wells containing azoles, indicating an azole-resistant phenotype. The results were read and recorded after 24 and 48 h of incubation at 35-37°C. Majority of our isolates had visible growth at 24 h. Sequence analysis of the CYP51A gene indicated the presence of M220K mutation in all 12 isolates and no mutations in the other isolates.

The fact that the azole resistance was found in A. fumigatus isolated from patients with previous azole exposure, underscores the possibility that prevalence of azole-resistance might be underestimated in various patient populations because in-vitro susceptibility testing of A. fumigatus is not routinely performed.

Conclusion

In conclusion, prevalence of azole resistance in clinical A. fumigatus isolates obtained from NIH patients underlying primary immunodeficiencies was 4.7%; all the resistant isolates exhibited azole-resistance mutation in Cyp51A gene.

Our finding adds to the growing list of regions where acquired resistance in A. fumigatus of is documented. Our results also indicate that 4-well triazole screen plates are a reliable tool for azole-resistance screening and the selection of isolates that require a full panel of antifungal susceptibility testing.

Incidence of Nontuberculous Mycobacterial Pulmonary Infection, by Ethnic Group, Hawaii, USA, 2005-2019

To further clarify differences in the risk for nontuberculous mycobacterial pulmonary infection (NTM-PI) among ethnic populations in Hawaii, USA, we conducted a retrospective cohort study among beneficiaries of Kaiser Permanente Hawaii (KPH). We abstracted demographic, socioeconomic, clinical, and microbiological data from KPH electronic health records for 2005-2019. An NTM-PI case-patient was defined as a person from whom >1 NTM pulmonary isolate was obtained. We performed Cox proportional hazards regression to estimate incidence of NTM-PI while controlling for confounders. Across ethnic groups, risk for NTM-PI was higher among persons who were underweight (body mass index [BMI] <18.5 kg/m²). Among beneficiaries who self-identified as any Asian ethnicity, risk for incident NTM-PI was increased by 30%. Low BMI may increase susceptibility to NTM-PI, and risk may be higher for persons who self-identify as Asian, independent of BMI.

Rapid detection of multiple SARS-CoV-2 variants of concern by PAM-targeting mutations

SARS-CoV-2 variants of concern (VOCs) that increase transmission or disease severity or reduce diagnostic or vaccine efficacy continue to emerge across the world. Current methods available to rapidly detect these can be resource intensive and thus sub-optimal for large-scale deployment needed during a pandemic response. Here, we describe a CRISPR-based assay that detects mutations in spike gene CRISPR PAM motif or seed regions to identify a pan-specific VOC single-nucleotide polymorphism (SNP)) ((D614G) and Alpha- and Delta-specific (S982A and D950N) SNPs. This assay exhibits good diagnostic sensitivity and strain specificity with nasal swabs and is designed for use in laboratory and point-of-care settings. This should enable rapid, high-throughput VOC identification required for surveillance and characterization efforts to inform clinical and public health decisions. Furthermore, the assay can be adapted to target similar SNPs associated with emerging SARS-CoV-2 VOCs, or other rapidly evolving viruses.

To Induce Immune Reconstitution Inflammatory Syndrome or Suppress It: The Spectrum of Mycobacterium genavense in the Antiretroviral Era

Mycobacterium  genavense is a challenging opportunistic pathogen to diagnose and manage in patients with human immunodeficiency virus (HIV). Persistent immunosuppression or protracted immune reconstitution inflammatory syndrome can lead to complicated clinical courses. We describe 3 cases of M. genavense in patients with HIV representing the spectrum between disease burden and strength of immune response.

Immune Reconstitution Inflammatory Syndrome as a Posttransplantation Complication in Primary Immunodeficiency With Disseminated Mycobacterium avium

Patients with primary immunodeficiencies undergoing allogeneic hematopoietic cell transplantation (HCT) for difficult-to-control infections can experience immune reconstitution inflammatory syndrome (IRIS) following engraftment. In 3 patients with post-HCT IRIS related to mycobacterial infection, in vitro data demonstrate the emergence of pathogen-specific immune responses and a concomitant rise in plasma inflammatory markers.

661. Futility of Bacterial Bone Marrow Cultures: Experience over a 19 Year Period

Background

Bone marrow biopsies are often performed on patients with unclear diagnoses and cultures may be ordered for both routine bacterial, mycobacterial and fungal pathogens. They are performed in semi-sterile conditions and involve needle penetration through the skin, posing an increased risk of skin contamination. These cultures also require a substantial amount of laboratory personnel time.

Methods

Cultures collected from 2001-2020 were surveyed in the lab electronic record. We assessed the culture type (fungal, bacterial, mycobacterial), and the presence of pathogens and contaminants. An organism was deemed a contaminant if it was consistent with skin flora or listed as a contaminant in the report given to the physician. Organisms for which the role in bone marrow disease is unclear were included as possible pathogens. For questionable non-contaminant organisms, clinical significance was determined based on if patient was treated for the organism. For all bone marrow cultures, growth of the same organism within 1 month of the bone marrow specimen was surveyed to determine whether the organism would have been found by alternative methods.

Results

Of 483 bacterial bone marrow cultures, there were 110 (23%) positives, of which 76 (69%) were deemed contaminants. Twenty (18%) of the 76 contaminants grew in the routine bacterial culture. However, 49 (65%) contaminants grew in the AFB culture, of which 10 also grew in the bacterial culture. For the 34 non-contaminant organisms, 26 were determined to be clinically significant. Nineteen of the 26 had a matching culture (usually blood) growing the organism within 1 month. The majority of pathogens were mycobacteria (18 of the 34). Fungal organisms represented 5 cultures and 11 were bacterial. Of the 11 bacterial organisms, 1 was a Helicobacter species (grown in special media), and 4 had a matching positive blood culture. Only 4 (1% of 483) bacterial non-contaminants grew in the routine bacterial culture. Given an unknown number of true negatives, we can only conclude a positive predictive value (PPV) of 0.16 for routine bacterial cultures. Including AFB and fungal cultures, the PPV increased to 0.30.

Conclusion

Our findings indicate that routine bacterial bone marrow culture is unlikely to yield a novel result and is likely a poor use of lab resources.

Disclosures

All Authors: No reported disclosures

Mycobacterial Testing Trends, United States, 2009-20151

We studied 31 US healthcare facilities to characterize trends in mycobacterial testing. During 2009-2015, testing for acid-fast bacilli increased 3.2% annually, and prevalence of pathogenic nontuberculous mycobacteria increased 4.5% annually. These increases were highest for subpopulations at high risk of infection, including older women, Asians, and patients with concurrent conditions.

Emergence of Polyfunctional Cytotoxic CD4+ T Cells in Mycobacterium avium Immune Reconstitution Inflammatory Syndrome in Human Immunodeficiency Virus-Infected Patients

Background

Immune reconstitution inflammatory syndrome (IRIS) is an aberrant inflammatory response in individuals with advanced human immunodeficiency virus (HIV) infection, after antiretroviral therapy (ART) initiation. The pathogenesis of Mycobacterium avium complex (MAC)-associated IRIS has not been fully elucidated.

Methods

We investigated monocyte and CD4+ T-cell responses in vitro, tumor necrosis factor (TNF) expression in tissues, and plasma cytokines and inflammatory markers, in 13 HIV-infected patients with MAC-IRIS and 14 HIV-uninfected patients with pulmonary MAC infection.

Results

Prior to ART, HIV-infected compared with HIV-uninfected patients, had reduced TNF+ monocytes (P = .013), although similar cytokine (interferon gamma [IFN-γ], TNF, interleukin 2 [IL-2], and interleukin 17 [IL-17])-expressing CD4+ T cells. During IRIS, monocyte cytokine production was restored. IFN-γ+ (P = .027), TNF+ (P = .004), and polyfunctional CD4+ T cells (P = 0.03) also increased. These effectors were T-betlow, and some expressed markers of degranulation and cytotoxic potential. Blockade of cytotoxic T-lymphocyte associated protein 4 and lymphocyte activation gene-3 further increased CD4+ T-cell cytokine production. Tissue immunofluorescence showed higher proportions of CD4+ and CD68+ (monocyte/macrophage) cells expressed TNF during IRIS compared with HIV-uninfected patients. Plasma IFN-γ (P = .048), C-reactive protein (P = .008), and myeloperoxidase (P < .001) levels also increased, whereas interleukin 10 decreased (P = .008) during IRIS.

Conclusions

Advanced HIV infection was associated with impaired MAC responses. Restoration of monocyte responses and expansion of polyfunctional MAC-specific T-betlow CD4+ T cells with cytotoxic potential after ART initiation may overwhelm existing regulatory and inhibitory mechanisms, leading to MAC-IRIS.

232. Genomic Evidence for Dissemination of Mycobacterium marinum in an HIV Patient with Multifocal Cutaneous Disease

Background

Hematogenous dissemination has been proposed to explain multifocal cutaneous disease caused by Mycobacterium marinum in certain patients. Treatment duration for disseminated disease is often months longer than for skin infection alone. However, distinguishing multiple independent inoculation events from dissemination has relied primarily on clinical judgement. Additionally, whether temperature-sensitive non-tuberculous mycobacteria such as M. marinum are indeed capable of invading the vascular space at core body temperature is debated. Here we used whole-genome sequencing (WGS) of serial isolates from a single patient with multifocal cutaneous M. marinum infection to distinguish dissemination of a clonal strain from multiple inoculation events.

Methods

A 35-year-old male with HIV (CD4 of 66 cells/µL) presented with a two-month history of a non-healing M. marinum wound on his left elbow (isolate MM0). This was followed a month later after initiation of antiretroviral therapy by a second M. marinum lesion on the right heel (MM1) without history of repeat inoculation, and increased swelling and erythema of the wound on the left arm (MM2) consistent with paradoxical immune reconstitution inflammatory syndrome. A PacBio genome was generated for MM0 and short read Illumina genomes were generated for MM1 and MM2.

Results

All isolates were found to be closely related, with MM1 and MM2 distinguished from MM0 by one and five single-nucleotide variants (SNVs), respectively. Given the substantial genetic heterogeneity among environmental M. marinum strains, such close relatedness of these isolates suggests common origin, and provides strong evidence for dissemination of a clonal strain in this patient. The SNVs included a frameshift mutation in the purT gene, which encodes a formate-dependent phosphoribosylglycinamide formyltransferase involved in de novo purine synthesis, and missense mutations in atsA and the DNA methylase hsdM. All isolates grew at 35°C, compared with the optimal growth temperature of 30°C typically observed for M. marinum, suggesting thermotolerance permissive for dissemination.

Conclusion

These results demonstrate the potential role of WGS for providing supportive evidence of disseminated infection with M. marinum.

Disclosures

All authors: No reported disclosures.

277. Identification and Antifungal Susceptibility of Candida Species Isolated from Bloodstream Infections Over a 14-Year Period

Background

Invasive infections caused by Candida species are associated with significant morbidity and mortality. Historically, C. albicans has been the predominant species recovered from patients with candidemia. However, the changing epidemiology of invasive candidiasis now includes more non-C. albicans species, which may exhibit intrinsic resistance or reduced susceptibility to antifungal agents used for therapeutic intervention. We sought to evaluate the epidemiology and susceptibility of invasive Candida ssp. isolates causing bloodstream infections at the NIH Clinical Center over a 14 year period.

Methods

Candida spp. isolates causing bloodstream infections between 2004 and 2018 were identified. Retrospective chart review was performed for infected patients in accordance with the IRB. All Candida isolates were recovered from frozen storage by plating onto Sabouraud Dextrose Agar, and isolate identities were confirmed by MALDI-TOF MS. Antifungal susceptibility testing was performed by broth microdilution and MICs were interpreted using current CLSI criteria.

Results

Between 2004–2018, we identified 98 unique clinical isolates from 77 patients with candidemia. Records from 75 of these patients were able to be reviewed, and the 30-day and 90-day mortalities were 24% and 52%, respectively. The average age at the time of culture positivity was 41.3 years (range 6.5 to 76.9 years). Thirty-one of the patients were female and 44 were male. C. albicans only constituted 18% of isolates (N = 18) and was the third-most prevalent Candida species identified behind C. parapsilosis (28%, N = 27) and C. glabrata (23%, N = 23), and followed by C. tropicalis (8%, N = 8) and C. krusei (6%, N = 6). As expected, fluconazole resistance was prevalent among C. glabrata (70%, N = 16) and C. krusei (100%, N = 6); however, a sizable proportion of C. parapsilosis (11%, N = 3), C. tropicalis (63%, N = 5) and C. albicans (22%, N = 4) strains also exhibited fluconazole resistance.

Conclusion

Our findings illustrate a high prevalence of non-C. albicans Candida spp. as the causative agents of bloodstream infections among patients at our institution. The clinical risk factors associated with the development of candidemia and azole resistance, as well as the molecular mechanisms of antifungal resistance are under investigation.

Disclosures

All authors: No reported disclosures.

VT-1598 inhibits the in vitro growth of mucosal Candida strains and protects against fluconazole-susceptible and -resistant oral candidiasis in IL-17 signalling-deficient mice

Background

Chronic mucocutaneous candidiasis (CMC) treatment often induces drug resistance, posing long-term challenges. A novel broad-spectrum fungal CYP51 inhibitor, VT-1598, specifically targets fungal CYP51, but not human CYP enzymes.

Objectives

To determine the efficacy of VT-1598 in the treatment of oral Candida infection caused by fluconazole-susceptible and -resistant clinical isolates.

Methods

The MICs of VT-1598 and fluconazole for 28 Candida isolates recovered from patients with inherited CMC were determined using CLSI M27-A3 and M27-S4 guidelines. Plasma and tongue VT-1598 or fluconazole concentrations were measured in mice following oral administration to determine tissue distribution. Tongue fungal load was determined in IL-17 signalling-deficient Act1-/- mice following sublingual Candida albicans infection and oral treatment with fluconazole or VT-1598.

Results

Among the 28 Candida isolates, 10 (36%) had fluconazole MICs of ≥4 mg/L, whereas VT-1598 demonstrated potent in vitro activity against all isolates (MIC90, 0.125 mg/L). After oral administration, VT-1598 levels in mouse plasma and tongue were significantly greater than those of fluconazole. In vivo, VT-1598 exhibited significant efficacy against fluconazole-susceptible and -resistant C. albicans, even at low drug doses. Furthermore, after a 10 day washout period, tongue fungal burdens in fluconazole-treated mice returned to vehicle control levels, whereas, in contrast, they were undetectable in mice treated with VT-1598.

Conclusions

VT-1598 effectively controls in vitro growth of mucosally derived Candida clinical isolates, including fluconazole-resistant strains. In vivo, VT-1598 eliminates C. albicans, even after a long washout period or at low doses. Therefore, VT-1598 is a promising drug candidate that may significantly improve treatment options for CMC patients.

Central Line-Associated Mucor velutinosus Bloodstream Infection in an Immunocompetent Pediatric Patient

We report here the isolation of Mucor velutinosus from multiple blood cultures performed on samples from Broviac catheters and culture of a Broviac insertion-site wound sample from a 6-year-old boy with a history of intestinal failure secondary to chronic intestinal pseudo-obstruction, parenteral nutrition, and jejunostomy tube dependence. Examination of a slide from the culture revealed the presence of wide nonseptate hyphae with sporangiophores, columella, and chlamydospores. The fungal isolate was sent to the National Institutes of Health for further evaluation and was identified as Mucor velutinosus by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and genomic sequencing. The patient was treated successfully with intravenous amphotericin B and prompt removal of his central line. To the best of our knowledge, this is the first case of M velutinosus bloodstream infection in a child without cancer.

Epidemiology of Nontuberculous Mycobacterial Lung Disease and Tuberculosis, Hawaii, USA

Previous studies found Hawaiians and Asian-Americans/Pacific Islanders to be independently at increased risk for nontuberculous mycobacterial pulmonary disease (NTMPD) and tuberculosis (TB). To better understand NTM infection and TB risk patterns in Hawaii, USA, we evaluated data on a cohort of patients in Hawaii for 2005–2013. Period prevalence of NTMPD was highest among Japanese, Chinese, and Vietnamese patients (>300/100,000 persons) and lowest among Native Hawaiians and Other Pacific Islanders (50/100,000). Japanese patients were twice as likely as all other racial/ethnic groups to have Mycobacterium abscessus isolated (adjusted odds ratio 2.0, 95% CI 1.2–3.2) but were not at increased risk for infection with other mycobacteria species. In contrast, incidence of TB was stable and was lowest among Japanese patients (no cases) and highest among Filipino, Korean, and Vietnamese patients (>50/100,000). Substantial differences exist in the epidemiology of NTMPD by race/ethnicity, suggesting behavioral and biologic factors that affect disease susceptibility.

Mortality among patients with pulmonary non-tuberculous mycobacteria disease

SETTING

Tertiary referral center, National Institutes of Health (NIH), USA.

OBJECTIVE

To estimate the mortality rate and its correlates among persons with pulmonary non-tuberculous mycobacteria (PNTM) disease.

DESIGN

A retrospective review of 106 patients who were treated at the NIH Clinical Center and met American Thoracic Society/Infectious Diseases Society of America criteria for PNTM. Eligible patients were aged ⩾18 years and did not have cystic fibrosis or human immunodeficiency virus (HIV) infection.

RESULTS

Of 106 patients followed for a median of 4.9 years, 27 (25%) died during follow-up, for a mortality rate of 4.2 per 100 person-years. The population was predominantly female (88%) and White (88%), with infrequent comorbidities. Fibrocavitary disease (adjusted hazard ratio [aHR] 3.3, 95% confidence interval [CI] 1.3-8.3) and pulmonary hypertension (aHR 2.1, 95%CI 0.9-5.1) were associated with a significantly elevated risk of mortality in survival analysis.

CONCLUSIONS

PNTM remains a serious public health concern, with a consistently elevated mortality rate across multiple populations. Significant risk factors for death include fibrocavitary disease and pulmonary hypertension. Further research is needed to more specifically identify clinical and microbiologic factors that jointly influence disease outcome.

Common severe infections in chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease (CGD) is due to defective nicotinamide adenine dinucleotide phosphate oxidase activity and characterized by recurrent infections with a limited spectrum of bacteria and fungi as well as inflammatory complications. To understand the impact of common severe infections in CGD, we examined the records of 268 patients followed at a single center over 4 decades.

METHODS

All patients had confirmed diagnoses of CGD, and genotype was determined where possible. Medical records were excerpted into a standard format. Microbiologic analyses were restricted to Staphylococcus, Burkholderia, Serratia, Nocardia, and Aspergillus.

RESULTS

Aspergillus incidence was estimated at 2.6 cases per 100 patient-years; Burkholderia, 1.06 per 100 patient-years; Nocardia, 0.81 per 100 patient-years; Serratia, 0.98 per 100 patient-years, and severe Staphylococcus infection, 1.44 per 100 patient-years. Lung infection occurred in 87% of patients, whereas liver abscess occurred in 32%. Aspergillus incidence was 55% in the lower superoxide-producing quartiles (quartiles 1 and 2) but only 41% in the higher quartiles (rate ratio, <0.0001). Aspergillus and Serratia were somewhat more common in lower superoxide producing gp91phox deficiency. The median age at death has increased from 15.53 years before 1990 to 28.12 years in the last decade. Fungal infection carried a higher risk of mortality than bacterial infection and was the most common cause of death (55%). Gastrointestinal complications were not associated with either infection or mortality.

CONCLUSIONS

Fungal infections remain a major determinant of survival in CGD. X-linked patients generally had more severe disease, and this was generally in those with lower residual superoxide production. Survival in CGD has increased over the years, but infections are still major causes of morbidity and mortality.

Abnormal nasal nitric oxide production, ciliary beat frequency, and Toll-like receptor response in pulmonary nontuberculous mycobacterial disease epithelium

RATIONALE

Pulmonary nontuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Despite extensive investigation, no consistent immunological abnormalities have been found. Using evidence from diseases such as cystic fibrosis and primary ciliary dyskinesia, in which mucociliary dysfunction predisposes subjects to high rates of nontuberculous mycobacterial disease that increase with age, we investigated correlates of mucociliary function in subjects with PNTM infections and healthy control subjects.

OBJECTIVES

To define ex vivo characteristics of PNTM disease.

METHODS

From 2009 to 2012, 58 subjects with PNTM infections and 40 control subjects were recruited. Nasal nitric oxide (nNO) was determined at the time of respiratory epithelial collection. Ciliary beat frequency at rest and in response to Toll-like receptor (TLR) and other agonists was determined using high-speed video microscopy.

MEASUREMENTS AND MAIN RESULTS

We found decreased nNO production, abnormally low resting ciliary beat frequency, and abnormal responses to agonists of TLR2, -3, -5, -7/8, and -9 in subjects with PNTM compared with healthy control subjects. The low ciliary beat frequency in subjects with PNTM was normalized ex vivo by augmentation of the NO-cyclic guanosine monophosphate pathway without normalization of their TLR agonist responses.

CONCLUSIONS

Impaired nNO, ciliary beat frequency, and TLR responses in PNTM disease epithelium identify possible underlying susceptibility mechanisms as well as possible avenues for directed investigation and therapy.

A high-throughput screening assay for fungicidal compounds against Cryptococcus neoformans

Cryptococcus neoformans is a pathogenic fungus that causes meningitis worldwide, particularly in human immunodeficiency virus (HIV)-infected individuals. Although amphotericin B is the "gold standard" treatment for cryptococcal meningitis, the toxicity and inconvenience of intravenous injection emphasize a need for development of new anticryptocccal drugs. Recent data from humans and animal studies suggested that a nutrient-deprived host environment may exist in cryptococcal meningitis. Thus, a screening assay for identifying fungicidal compounds under nutrient-deprived conditions may provide an alternative strategy to develop new anticryptococcal drugs for this disease. A high-throughput fungicidal assay was developed using a profluorescent dye, alamarBlue, to detect residual metabolic activity of C. neoformans under nutrient-limiting conditions. Screening the Library of Pharmacologically Active Compounds (LOPAC) with this assay identified a potential chemical scaffold, 10058-F4, that exhibited fungicidal activity in the low micromolar range. These results thus demonstrate the feasibility of this alamarBlue-based assay for high-throughput screening of fungicidal compounds under nutrient-limiting conditions for new anticryptococcal drug development.

The capsular polysaccharide and lipopolysaccharide structures of two carbapenem resistant Klebsiella pneumoniae outbreak isolates

Carbapenem resistant Klebsiella pneumoniae (CRKP) are isolated with increasing frequency, especially from immunocompromized patients. The capsular polysaccharide (CPS) types of CPKP were not determined. Investigation of two CRKP isolates from a 2011 outbreak at the Clinical Center, the National Institutes of Health, identified a new capsular type shared by the two isolates, similar to K. pneumonia K19 and K34 but structurally different than any published K. pneumoniae CPS repeating unit: The LPS of the two isolates was found to have no O-specific polysaccharide and the chemical structure of the core oligosaccharides agreed with the published data. If this structure type will be prevalent among CPKP isolates, our findings could facilitate rapid diagnosis and help to develop new therapeutic solutions to this antibiotic resistant pathogen.

Viability and burden of Leishmania in extralesional sites during human dermal leishmaniasis

Background

The clinical and epidemiological significance of Leishmania DNA in extralesional sites is obscured by uncertainty of whether the DNA derives from viable parasites. To examine dissemination of Leishmania during active disease and the potential participation of human infection in transmission, Leishmania 7SLRNA was exploited to establish viability and estimate parasite burden in extralesional sites of dermal leishmaniasis patients.

Methods

The feasibility of discriminating parasite viability by PCR of Leishmania 7SLRNA was evaluated in relation with luciferase activity of luc transfected intracellular amastigotes in dose-response assays of Glucantime cytotoxicity. Monocytes, tonsil swabs, aspirates of normal skin and lesions of 28 cutaneous and 2 mucocutaneous leishmaniasis patients were screened by kDNA amplification/Southern blot. Positive samples were analyzed by quantitative PCR of Leishmania 7SLRNA genes and transcripts.

Results

7SLRNA amplification coincided with luciferase activity, confirming discrimination of parasite viability. Of 22 patients presenting kDNA in extralesional samples, Leishmania 7SLRNA genes or transcripts were detected in one or more kDNA positive samples in 100% and 73% of patients, respectively. Gene and transcript copy number amplified from extralesional tissues were comparable to lesions. 7SLRNA transcripts were detected in 13/19 (68%) monocyte samples, 5/12 (42%) tonsil swabs, 4/11 (36%) normal skin aspirates, and 22/25 (88%) lesions; genes were quantifiable in 15/19 (79%) monocyte samples, 12/13 (92%) tonsil swabs, 8/11 (73%) normal skin aspirates.

Conclusion

Viable parasites are present in extralesional sites, including blood monocytes, tonsils and normal skin of dermal leishmaniasis patients. Leishmania 7SLRNA is an informative target for clinical and epidemiologic investigations of human leishmaniasis.

Understanding of the dynamics and distribution of Leishmania in the human host is fundamental to the targeting of control measures and their evaluation. Amplification of parasite gene sequences in clinical samples from cutaneous leishmaniasis patients has provided evidence of Leishmania in blood, other tissues and sites distinct from the lesion and of persistence of infection after clinical resolution of disease. However, there is uncertainty about the interpretation of the presence of Leishmania DNA as indicative of viable parasites. Because RNA is short-lived and labile, its presence provides an indicator of viability. We amplified Leishmania 7SLRNA, a molecule involved in intracellular protein translocation, to establish viability and estimate parasite load in blood monocytes, tonsil swab samples, and tissue fluid from healthy skin of patients with dermal leishmaniasis. Results showed that during active dermal leishmaniasis, viable Leishmania are present in blood monocytes, tonsils and normal skin in quantities similar to that in lesions, demonstrating widespread dissemination of infection and subclinical involvement of tissues beyond the lesion site. Leishmania 7SLRNA will be useful in deciphering the role of human infection in transmission.

Chronic invasive aspergillosis caused by Aspergillus viridinutans

Aspergillus viridinutans, a mold phenotypically resembling A. fumigatus, was identified by gene sequence analyses from 2 patients. Disease was distinct from typical aspergillosis, being chronic and spreading in a contiguous manner across anatomical planes. We emphasize the recognition of fumigati-mimetic molds as agents of chronic or refractory aspergillosis.

Invasive aspergillosis due to Neosartorya udagawae

BACKGROUND

Invasive aspergillosis (IA) is most commonly caused by the morphospecies Aspergillus fumigatus. However, genetic-based methods indicate that organisms phenotypically identified as A. fumigatus actually constitute a mold complex, designated Aspergillus section fumigati subgenus fumigati.

METHODS

Multilocus sequencing and analysis was performed on fungi identified as A. fumigatus from the clinical culture collection maintained at the National Institutes of Health from 2000 through 2008, with a focus on the internal transcribed spacer 1 and 2 regions of ribosomal DNA (rDNA), beta-tubulin, and rodlet A genes. We reviewed the medical records, radiology, and histopathology of corresponding patients. To confirm identification of Neosartorya udagawae isolates, mating studies were performed with reference strains. Antifungal susceptibility testing was performed by broth microdilution and read at 48 hours.

RESULTS

Thirty-six cases of infection attributed to A. fumigatus were identified; 4 were caused by N. udagawae (3 in patients with chronic granulomatous disease and 1 in a patient with myelodysplastic syndrome). Disease due to N. udagawae was chronic, with a median duration of 35 weeks, compared with a median duration of 5.5 weeks for patients with chronic granulomatous disease who had infection due to A. fumigatus sensu stricto (P < .05 , Mann-Whitney U test). Infection spread across anatomical planes in a contiguous manner and was refractory to standard therapy. Two of the 4 patients died. N. udagawae demonstrated relatively higher minimum inhibitory concentrations to various agents, compared with those demonstrated by contemporary A. fumigatus sensu stricto isolates.

CONCLUSIONS

To our knowledge, this is the first report documenting infection due to N. udagawae. Clinical manifestations were distinct from those of typical IA. Fumigati-mimetics with inherent potential for antifungal resistance are agents of IA. Genetic identification of molds should be considered for unusual or refractory IA.

Mycobacterium abscessus and M. avium trigger Toll-like receptor 2 and distinct cytokine response in human cells

Mycobacterium avium (MAV) and M. abscessus (MAB) are ubiquitous environmental organisms increasingly recognized to cause chronic lung disease in patients with apparently normal immune function. Little is yet known about their human pathophysiology. Our objective was to examine cytokine and chemokine responses (protein and gene expression) and signaling pathways triggered by reference and clinical isolates of MAB and MAV in human peripheral blood mononuclear cells, monocytes, and murine bone marrow-derived macrophages in vitro. MAB-induced TNF-alpha production was higher than that induced by MAV. IFN-gamma, IL-1beta, and the chemokines macrophage inflammatory protein-1alpha and regulated on activation, normal T cell expressed and secreted were equally up-regulated. Differences between MAB and MAV do not require replication and are heat stable. We found no differential effect due to rough or smooth colonies within the same species. Similar to MAV, MAB triggered mitogen-activated protein kinase (MAPK) signaling and nuclear factor-kappaB translocation. Induction of TNF-alpha was dependent on MAPK pathways, since pre-incubation of cells with signaling inhibitors led to more than 85% reduction in cytokine secretion. MAB also triggered a Toll-like receptor 2 (TLR2)-mediated response that led to TNF-alpha production by human monocytes. Accordingly, stimulation of murine TLR2- or myeloid differentiation factor 88-deficient bone marrow-derived macrophages did not elicit TNF-alpha, reinforcing a critical role for TLR2 in MAB-induced cell activation. We concluded that MAB signals human cells through MAPK and TLR2 pathways and triggers more pronounced pro-inflammatory cytokines and chemokines than MAV.

Mass antibiotic treatment to stop an outbreak of meningococcal disease: a molecular analysis

The occurrence of three cases of meningococcal disease among children in a small community, two of whom attended the same day-care centre, prompted a programme of mass antibiotic prophylaxis. Nasopharyngeal and throat swabs were obtained on three occasions from all children registered at the day-care centre. Serogroup B Neisseria meningitidis was isolated from 13 of 61 children before prophylaxis, from three children after 2 weeks, and from 19 children after 3 months. Repetitive extragenic palindromic PCR analysis identified several meningococcal strains before treatment, one of which became predominant after 3 months. Mass antibiotic prophylaxis initially suppressed meningococcal carriage, but the carriage rate subsequently rebounded.

Target-directed proteolysis at the ribosome

Target directed proteolysis allows specific processing of proteins in vivo. This method uses tobacco etch virus (TEV) NIa protease that recognizes a seven-residue consensus sequence. Because of its specificity, proteins engineered to contain a cleavage site are proteolysed, whereas other proteins remain unaffected. Therefore, this approach can be used to study the structure and function of target proteins in their natural environment within living cells. One application is the conditional inactivation of essential proteins, which is based on the concept that a target containing a recognition site can be inactivated by coexpressed TEV protease. We have previously identified one site in the secretion factor SecA that tolerated a TEV protease site insert. Coexpression of TEV protease in the cytoplasm led to incomplete cleavage and a mild secretion defect. To improve the efficiency of proteolysis, TEV protease was attached to the ribosome. We show here that cleaving SecA under these conditions is one way of increasing the efficiency of target directed proteolysis. The implications of recruiting novel biological activities to ribosomes are discussed.

An Outbreak of Phialemonium Infective Endocarditis Linked to Intracavernous Penile Injections for the Treatment of Impotence

BACKGROUND

In March 2002, a patient in Tel Aviv, Israel, died of endocarditis caused by Phialemonium curvatum. As part of his therapy for erectile dysfunction, the patient had been trained to self-inject a compound of vasoactive drugs provided by an impotence clinic into his penile corpus cavernosous.

METHODS

We identified the used prefilled syringes as the source of his infection. Similar cases were investigated as a putative outbreak of P. curvatum invasive disease among customers of this impotence clinic. P. curvatum isolates, cultured from samples obtained from the patients and from prefilled syringes, were compared by DNA sequencing of the nuclear ribosomal internal transcribed spacer.

RESULTS

We identified 2 additional customers at the impotence clinic who had P. curvatum endocarditis. In addition, cultures of unused, prefilled syringes and bottles provided by the same clinic to 5 asymptomatic customers tested positive for pathogenic molds (P. curvatum in 4 cases and Paecilomyces lilacinus in 1). All P. curvatum isolates were of a single genetic type that is known only from this outbreak but is closely related to 3 other P. curvatum genotypes associated with pathogenicity in humans.

CONCLUSIONS

P. curvatum is an emerging pathogen that can be readily isolated from blood. We identified an outbreak of P. curvatum endocarditis among men who had erectile dysfunction treated by intracavernous penile injections from contaminated prefilled syringes.

Molecular epidemiological analysis of the changing nature of a meningococcal outbreak following a vaccination campaign

A serogroup C meningococcal outbreak that occurred in an Israeli Arab village led to a massive vaccination campaign. During the subsequent 18 months, new cases of type B Neisseria meningitidis infection were revealed. To investigate the influence of vaccination on bacteriological epidemiology, bacteria were isolated from individuals at the outbreak location, patients with several additional other sporadic cases, and patients involved in another outbreak. Haploid bacterial genomic DNA was mixed with a consensus PCR product to form a heteroduplex state that enabled multilocus sequence typing (MLST) to be combined with denaturing high-performance liquid chromatography (DHPLC) for a novel high-throughput molecular typing method called MLST-DHPLC. A 100% correlation was found to exist between the sequencing by MLST alone and the MLST-DHPLC method. Independent molecular typing by repetitive extragenic palindromic PCR discriminated the neisserial clones as well as the MLST-DHPLC method did. The occurrence of type B N. meningitidis in the postvaccination period might be attributed to the selection pressure applied to the bacteria by vaccination, suggesting a possible unwarranted outcome of vaccination with the quadrivalent vaccine for control of a serogroup C meningococcal outbreak. This is the first time that DHPLC has been applied to the genotyping of bacteria, and it proved to be more efficient than MLST alone.

The NG domain of the prokaryotic signal recognition particle receptor, FtsY, is fully functional when fused to an unrelated integral membrane polypeptide

Recent studies have revealed that Escherichia coli possesses an essential targeting system for integral membrane proteins, similar to the mammalian signal recognition particle (SRP) machinery. One essential protein in this system is FtsY, a homologue of the alpha-subunit of the mammalian SRP-receptor (SR-alpha). However, E. coli does not possess a close homologue of the integral membrane protein SR-beta, which anchors SR-alpha to the membrane. Moreover, although FtsY can be found as a peripheral membrane protein, the majority is found soluble in the cytoplasm. In this study, we obtained genetic and biochemical evidence that FtsY must be targeted to the membrane for proper function. We demonstrate that the essential membrane targeting activity of FtsY is mediated by a 198-residue-long acidic N-terminal domain. This domain can be functionally replaced by unrelated integral membrane polypeptides, thus avoiding the need for specific FtsY membrane targeting factors. Therefore, the N terminus of FtsY constitutes an independent domain, which is required only for the targeting of the C-terminal NG domain of FtsY to the membrane.

Quantitative analysis of the plain radiographic appearance of Ewing's sarcoma of bone

RATIONALE AND OBJECTIVES

The authors quantitate the radiographic features that distinguish the plain radiographic appearance of Ewing's sarcoma (ES) from other solitary lesions of bone.

METHODS

A total of 709 cases of focal bone lesions, including 44 ES, were analyzed according to demographic, anatomic, and plain radiographic features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the appearance of ES in contrast with other lesions in the database.

RESULTS

In our sample, Ewing's sarcoma is most consistently a medullary-based (91%) lytic (89%) lesion with at least a partially permeative appearance (82%), poorly defined edges (82%), no margination (91%), and a soft-tissue mass (61%). When these lesions occur in long bones, they most commonly are found in the diaphysis (75%) and are proximal more often than distal. Vector analysis suggests that any primary bone lesion without radiographically visible matrix and with either a soft-tissue mass, an appearance of permeative destruction alone or in combination with other patterns of bone destruction is suspect for the diagnosis. This small subset of common features appears to have a high sensitivity (89%) and prevalence (47%) of ES among the lesions meeting these criteria. Limiting the age of the patients to progressively younger age groups increases the specificity but lowers sensitivity. The vector analysis-generated differential diagnoses includes osteosarcoma, giant-cell tumor, lymphoma, and chondrosarcoma.

CONCLUSIONS

A relatively specific set of radiographic features can be defined, which will assist in the radiographic diagnosis of ES and improve upon current textbook descriptions.

Biogenesis and topology of integral membrane proteins: characterization of lactose permease-chloramphenicol acetyltransferase hybrids

Use of beta-lactamase in gene fusions to study membrane protein topology permits exploitation of its biological activity to select for positive (external) hybrids on ampicillin agar plates. When the enzyme is attached to cytoplasmic loops of a membrane protein, it is not secreted and is therefore unable to confer ampicillin resistance. In this study, we examine the use of the cytoplasmic enzyme chloramphenicol acetyltransferase (Cat) as a complement to the use of periplasmic beta-lactamase, in gene fusion studies. This enzyme is responsible for chloramphenicol resistance in Escherichia coli. We show that Cat confers substantial antibiotic resistance when fused to cytoplasmic loops of lactose permease. As expected, periplasmically exposed Cat is enzymatically active in vitro but unable to confer significant chloramphenicol resistance, presumably because of the absence of acetylcoenzyme A in the periplasm. Therefore, Cat may serve as a topogenic sensor in gene fusion studies. The new Cat fusion approach is discussed with regard to its potential use for selecting E. coli mutants which are defective in the assembly of membrane proteins.