Nathan C Bahr

Dr. Nathan C Bahr

Division of Infectious Diseases, Department of Medicine, University of Kansas Medical Center, Kansas City, KS, USA
orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 March 2016 in Infectious Disease Clinics of North America
Verified
Journal Article
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LWL. Joseph J. Wheat
L. Joseph J. Wheat
MAMarwan M. Azar
Marwan M. Azar
Nathan C BahrNathan C Bahr
Nathan C Bahr
ASAndrej Spec
Andrej Spec
RRRyan F. Relich
Ryan F. Relich
CHChadi Hage
Chadi Hage

10 February 2020 in Mycopathologia
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Journal Article
Open access
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NANida Ashraf
Nida Ashraf
RKRyan C. Kubat
Ryan C. Kubat
VPVictoria Poplin
Victoria Poplin
AAAntoine A. Adenis
Antoine A. Adenis
DDDavid W. Denning
David W. Denning
Nathan C BahrNathan C Bahr
Nathan C Bahr
Endemic mycoses such as histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, and talaromycosis are well-known causes of focal and systemic disease within specific geographic areas of known endemicity. However, over the past few decades, there have been increasingly frequent reports of infections due to endemic fungi in areas previously thought to be “non-endemic.” There are numerous potential reasons for this shift such as increased use of immune suppressive medications, improved diagnostic tests, increased disease recognition, and global factors such as migration, increased travel, and climate change. Regardless of the causes, it has become evident that our previous understanding of endemic regions for these fungal diseases needs to evolve. The epidemiology of the newly describedEmergomycesis incomplete; our understanding of it continues to evolve. This review will focus on the evidence underlying the established areas of endemicity for these mycoses as well as new data and reports from medical literature that support the re-thinking these geographic boundaries. Updating the endemic fungi maps would inform clinical practice and global surveillance of these diseases.

1 January 2018 in The Lancet Infectious Diseases
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Journal Article
Open access
Nathan C BahrNathan C Bahr
Nathan C Bahr
ENEdwin Nuwagira
Edwin Nuwagira
EEEmily E Evans
Emily E Evans
FCFiona V Cresswell
Fiona V Cresswell
PBPhilip V Bystrom
Philip V Bystrom
RRRadha Rajasingham
Radha Rajasingham
WHO recommends Xpert MTB/RIF as initial diagnostic testing for tuberculous meningitis. However, diagnosis remains difficult, with Xpert sensitivity of about 50-70% and culture sensitivity of about 60%. We evaluated the diagnostic performance of the new Xpert MTB/RIF Ultra (Xpert Ultra) for tuberculous meningitis. We prospectively obtained diagnostic cerebrospinal fluid (CSF) specimens during screening for a trial on the treatment of HIV-associated cryptococcal meningitis in Mbarara, Uganda. HIV-infected adults with suspected meningitis (eg, headache, nuchal rigidity, altered mental status) were screened consecutively at Mbarara Regional Referral Hospital. We centrifuged CSF, resuspended the pellet in 2 mL of CSF, and tested 0·5 mL with mycobacteria growth indicator tube culture, 1 mL with Xpert, and cryopreserved 0·5 mL, later tested with Xpert Ultra. We assessed diagnostic performance against uniform clinical case definition or a composite reference standard of any positive CSF tuberculous test. From Feb 27, 2015, to Nov 7, 2016, we prospectively evaluated 129 HIV-infected adults with suspected meningitis for tuberculosis. 23 participants were classified as probable or definite tuberculous meningitis by uniform case definition, excluding Xpert Ultra results. Xpert Ultra sensitivity was 70% (95% CI 47-87; 16 of 23 cases) for probable or definite tuberculous meningitis compared with 43% (23-66; 10/23) for Xpert and 43% (23-66; 10/23) for culture. With composite standard, we detected tuberculous meningitis in 22 (17%) of 129 participants. Xpert Ultra had 95% sensitivity (95% CI 77-99; 21 of 22 cases) for tuberculous meningitis, which was higher than either Xpert (45% [24-68]; 10/22; p=0·0010) or culture (45% [24-68]; 10/22; p=0·0034). Of 21 participants positive by Xpert Ultra, 13 were positive by culture, Xpert, or both, and eight were only positive by Xpert Ultra. Of those eight, three were categorised as probable tuberculous meningitis, three as possible tuberculous meningitis, and two as not tuberculous meningitis. Testing 6 mL or more of CSF was associated with more frequent detection of tuberculosis than with less than 6 mL (26% vs 7%; p=0·014). Xpert Ultra detected significantly more tuberculous meningitis than did either Xpert or culture. WHO now recommends the use of Xpert Ultra as the initial diagnostic test for suspected tuberculous meningitis. National Institute of Neurologic Diseases and Stroke, Fogarty International Center, National Institute of Allergy and Infectious Disease, UK Medical Research Council/DfID/Wellcome Trust Global Health Trials, Doris Duke Charitable Foundation.

11 April 2015 in Current Tropical Medicine Reports
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Journal Article
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Nathan C BahrNathan C Bahr
Nathan C Bahr
Spinello AntinoriSpinello Antinori
Spinello Antinori
LWL. Joseph J. Wheat
L. Joseph J. Wheat
GSGeorge A. Sarosi
George A. Sarosi

1 July 2016 in The Lancet Infectious Diseases
Verified
Journal Article
Open access
JRJoshua Rhein
Joshua Rhein
BMBozena M Morawski
Bozena M Morawski
KHKathy Huppler Hullsiek
Kathy Huppler Hullsiek
HNHenry W Nabeta
Henry W Nabeta
RKReuben Kiggundu
Reuben Kiggundu
DBDavid Boulware
David Boulware
Cryptococcus is the most common cause of adult meningitis in Africa. We assessed the safety and microbiological efficacy of adjunctive sertraline, previously shown to have in-vitro and in-vivo activity against cryptococcus. In this open-label dose-finding study, we recruited HIV-infected individuals with cryptococcal meningitis who presented to Mulago Hospital in Kampala, Uganda between Aug 14, 2013, and Aug 30, 2014. To assess safety and tolerability, the first 60 participants were given sertraline at escalating doses of 100 mg/day, 200 mg/day, 300 mg/day, or 400 mg/day as induction therapy for 2 weeks, followed by consolidation therapy with 200 mg/day for an additional 8 weeks. From Nov 29, 2013, participants were randomly assigned (1:1) to receive open-label sertraline at predetermined doses of 200 mg/day, 300 mg/day, or 400 mg/day as induction therapy for 2 weeks, followed by consolidation therapy with 200 mg/day for 8 weeks. Dose assignment was made via computer-generated, permuted block randomisation stratified by antiretroviral therapy (ART) status for people with a first episode of meningitis. The primary outcome was 2-week cerebrospinal fluid (CSF) clearance rate of cryptococcus, termed early fungicidal activity, measured in patients with a first episode of culture-positive meningitis and two or more CSF cultures. This study is registered with ClinicalTrials.gov, number NCT01802385. Of the 330 individuals assessed, 172 HIV-infected adults with cryptococcal meningitis were enrolled. We gave 100 mg/day sertraline to 17 patients, 200 mg/day to 12 patients, 300 mg/day to 14 patients, and 400 mg/day to 17 patients. 112 participants were randomly assigned to receive sertraline at 200 mg (n=48), 300 mg (n=36), or 400 mg (n=28) daily for the first 2 weeks, and 200 mg/day thereafter. The final population consisted of 17 participants in the 100 mg group, 60 in the 200 mg group, 50 in the 300 mg group, and 45 in the 400 mg in group. Participants receiving any sertraline dose averaged a CSF clearance rate of -0·37 colony forming units per mL per day (95% CI -0·41 to -0·33). Incidence of paradoxical immune reconstitution inflammatory syndrome was 5% (two of 43 newly starting ART) and no cases of relapse occurred over the 12-week study period. 38 (22%) of 172 participants had died at 2 weeks, and 69 (40%) had died at 12 weeks. Six grade 4 adverse events occurred in 17 participants receiving 100 mg, 14 events in 60 participants receiving 200 mg, 19 events in 50 participants receiving 300 mg, and eight events in 45 participants receiving 400 mg. Grade 4 or 5 adverse event risk did not differ between current US Food and Drug Administration-approved dosing of 100-200 mg/day and higher doses of 300-400 mg/day (hazard ratio 1·27, 95% CI 0·69-2·32; p=0·45). Participants receiving sertraline had faster cryptococcal CSF clearance and a lower incidence of immune reconstitution inflammatory syndrome and relapse than that reported in the past. This inexpensive and off-patent oral medication is a promising adjunctive antifungal therapy. National Institutes of Health, Grand Challenges Canada.

23 September 2015 in Seminars in Respiratory and Critical Care Medicine
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Journal Article
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MAMarwan M. Azar
Marwan M. Azar
Nathan C BahrNathan C Bahr
Nathan C Bahr
JLJames Loyd
James Loyd
CHChadi hage
Chadi hage
LWL. Joseph J. Wheat
L. Joseph J. Wheat
Histoplasmosis is the most common endemic mycosis in the North America, Central America, and many countries of South America and also occurs in China, India, Southeast Asia, Africa, Australia, and Europe. Clinical syndromes are not specific and histoplasmosis often is overlooked in the evaluation of patients with community-acquired pneumonia, chronic cavitary pneumonia resembling tuberculosis or anaerobic infection, granulomatous inflammatory diseases such as sarcoidosis or Crohn disease, and malignancy. The diagnosis depends on understanding the geographic distribution, common clinical presentations, and tests used for diagnosis of histoplasmosis. While histoplasmosis resolves without treatment in most patients, treatment is indicated in all immunocompromised patients and those with progressive disseminated disease or chronic pulmonary disease. Treatment is appropriate in most patients with acute pulmonary disease but rarely in those with other pulmonary or mediastinal manifestations. The preferred agents include liposomal amphotericin B for more severe cases and itraconazole for milder cases and “step-down” therapy following response to amphotericin B.