Reproducibility of CSF quantitative culture methods for estimating rate of clearance in cryptococcal meningitis.

Quantitative cerebrospinal fluid (CSF) cultures provide a measure of disease severity in cryptococcal meningitis. The fungal clearance rate by quantitative cultures has become a primary endpoint for phase II clinical trials. This study determined the inter-assay accuracy of three different quantitative culture methodologies. Among 91 participants with meningitis symptoms in Kampala, Uganda, during August-November 2013, 305 CSF samples were prospectively collected from patients at multiple time points during treatment. Samples were simultaneously cultured by three methods: (1) St. George's 100 mcl input volume of CSF with five 1:10 serial dilutions, (2) AIDS Clinical Trials Group (ACTG) method using 1000, 100, 10 mcl input volumes, and two 1:100 dilutions with 100 and 10 mcl input volume per dilution on seven agar plates; and (3) 10 mcl calibrated loop of undiluted and 1:100 diluted CSF (loop). Quantitative culture values did not statistically differ between St. George-ACTG methods (P= .09) but did for St. George-10 mcl loop (P< .001). Repeated measures pairwise correlation between any of the methods was high (r≥0.88). For detecting sterility, the ACTG-method had the highest negative predictive value of 97% (91% St. George, 60% loop), but the ACTG-method had occasional (∼10%) difficulties in quantification due to colony clumping. For CSF clearance rate, St. George-ACTG methods did not differ overall (mean -0.05 ± 0.07 log10CFU/ml/day;P= .14) on a group level; however, individual-level clearance varied. The St. George and ACTG quantitative CSF culture methods produced comparable but not identical results. Quantitative cultures can inform treatment management strategies

Diagnostic accuracy of Xpert MTB/RIF Ultra for tuberculous meningitis in HIV-infected adults: a prospective cohort study.

BACKGROUND: 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. METHODS: 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. FINDINGS: 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). INTERPRETATION: 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. FUNDING: 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

Xpert MTB/RIF Ultra for the diagnosis of HIV-associated tuberculous meningitis: a prospective validation study.

INTRODUCTION: Tuberculous meningitis accounts for 1-5% of tuberculosis cases. Diagnostic delay contributes to poor outcomes. We evaluated the performance of the new Xpert MTB/RIF Ultra (Xpert Ultra) for tuberculous meningitis diagnosis. METHODS: In this prospective validation study, we tested the cerebrospinal fluid (CSF) of adults presenting with suspected meningitis (ie, headache or altered mental status with clinical signs of meningism) to the Mulago National Referral Hospital and Mbarara Regional Referral Hospital in Uganda. We centrifuged the CSF, resuspended the cell pellet in 2 mL CSF, and tested 0·5 mL aliquots with Xpert Ultra, Xpert MTB/RIF (Xpert), and mycobacterial growth indicator tube (MGIT) culture. We quantified diagnostic performance against the uniform case definition of probable or definite tuberculous meningitis and a composite microbiological reference standard. FINDINGS: From Nov 25, 2016, to Jan 24, 2019, we screened 466 adults with suspected meningitis and tested 204 for tuberculous meningitis. Uniform clinical case definition classified 51 participants as having probable or definite tuberculous meningitis. Against this uniform case definition, Xpert Ultra had 76·5% sensitivity (95% CI 62·5-87·2; 39 of 51 patients) and a negative predictive value of 92·7% (87·6-96·2; 153 of 165), compared with 55·6% sensitivity (44·0-70·4; 25 of 45; p=0·0010) and a negative predictive value of 85·8% (78·9-91·1; 121 of 141) for Xpert and 61·4% sensitivity (45·5-75·6; 27 of 44; p=0·020) and negative predictive value of 85·2% (77·4-91·1; 98 of 115) for MGIT culture. Against the composite microbiological reference standard, Xpert Ultra had sensitivity of 92·9% (80·5-98·5; 39 of 42), higher than Xpert at 65·8% (48·6-80·4; 25 of 38; p=0·0063) and MGIT culture at 72·2% (55·9-86·2; 27 of 37; p=0·092). Xpert Ultra detected nine tuberculous meningitis cases missed by Xpert and MGIT culture. INTERPRETATION: Xpert Ultra detected tuberculous meningitis with higher sensitivity than Xpert and MGIT culture in this HIV-positive population. However, with a negative predictive value of 93%, Xpert Ultra cannot be used as a rule-out test. Clinical judgment and novel highly sensitive point-of-care tests are still required. FUNDING: Wellcome Trust, National Institute of Health, National Institute of Neurologic Diseases and Stroke, Fogarty International Center, and National Institute of Allergy and Infectious Diseases

Association of Hyponatremia on Mortality in Cryptococcal Meningitis: A Prospective Cohort.

BACKGROUND: Sodium abnormalities are frequent in CNS infections and may be caused by cerebral salt wasting, syndrome of inappropriate antidiuretic hormone secretion (SIADH), or medication adverse events. In cryptococcal meningitis, the prevalence of baseline hyponatremia and whether hyponatremia adversely impacts survival is unknown. METHODS: We conducted a secondary analysis of data from two randomized trials of HIV-infected adult Ugandans with cryptococcal meningitis. We grouped serum sodium into 3 categories: &amp;lt;125, 125-129, and 130-145 mmol/L. We assessed whether baseline sodium abnormalities were associated with clinical characteristics and survival. RESULTS: Of 816 participants with cryptococcal meningitis, 741 (91%) had a baseline sodium measurement available: 121 (16%) had Grade 3-4 hyponatremia (&amp;lt;125 mmol/L), 194 (26%) had Grade 2 hyponatremia (125-129 mmol/L), and 426 (57%) had a baseline sodium of 130-145 mmol/L. Hyponatremia (&amp;lt;125 mmol/L) was associated with higher initial CSF quantitative culture burden (P &amp;lt; .001), higher initial CSF opening pressure (P &amp;lt; 0.01), lower baseline Glasgow Coma Score (P &amp;lt; 0.01), and a higher percentage of baseline seizures (P = .03). Serum sodium &amp;lt;125 mmol/L was associated with increased 2-week mortality in unadjusted and adjusted survival analyses; adjusted hazard ratio of 1.87 (95%CI, 1.26 to 2.79; p &amp;lt; 0.01) compared to those with sodium 130-145 mmol/L. CONCLUSIONS: yponatremia is common in cryptococcal meningitis and is associated with excess mortality. A standardized management approach to correctly diagnose and correct hyponatremia in cryptococcal meningitis needs to be developed and tested

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The Changing Epidemiology of HIV-Associated Adult Meningitis, Uganda 2015–2017.

BACKGROUND: Central nervous system (CNS) infections remain a major public health problem in Sub-Saharan Africa, causing 15%-25% of AIDS-related deaths. With widespread availability of antiretroviral therapy (ART) and the introduction of improved diagnostics, the epidemiology of infectious meningitis is evolving. METHODS: We prospectively enrolled adults presenting with HIV-associated meningitis in Kampala and Mbarara, Uganda, from March 2015 to September 2017. Participants had a structured, stepwise diagnostic algorithm performed of blood cryptococcal antigen (CrAg), CSF CrAg, Xpert MTB/RIF for tuberculous (TB) meningitis (TBM), Biofire multiplex polymerase chain reaction, and traditional microscopy and cultures. RESULTS: We screened 842 consecutive adults with HIV presenting with suspected meningitis: 57% men, median age 35 years, median CD4 26 cells/mcL, and 55% presented on ART. Overall, 60.5% (509/842) were diagnosed with first-episode cryptococcal meningitis and 7.4% (62/842) with second episode. Definite/probable TB meningitis was the primary diagnosis in 6.9% (58/842); 5.3% (n = 45) had microbiologically confirmed (definite) TB meningitis. An additional 7.8% (66/842) did not meet the diagnostic threshold for definite/probable TBM but received empiric TBM therapy. Bacterial and viral meningitis were diagnosed in 1.3% (11/842) and 0.7% (6/842), respectively. The adoption of a cost-effective stepwise diagnostic algorithm allowed 79% (661/842) to have a confirmed microbiological diagnosis at an average cost of $44 per person. CONCLUSIONS: Despite widespread ART availability, Cryptococcus remains the leading cause of HIV-associated meningitis. The second most common etiology was TB meningitis, treated in 14.7% overall. The increased proportion of microbiologically confirmed TBM cases reflects the impact of new improved molecular diagnostics