title: Reproducibility of CSF quantitative culture methods for estimating rate of clearance in cryptococcal meningitis.
abstract: 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.
authors.affiliation: University of Minnesota, Minneapolis, Minnesota Infectious Disease Institute, Makerere University, Kampala, Uganda.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dyal
authors.affiliation: Infectious Disease Institute, Makerere University, Kampala, Uganda Makerere University College of Health Sciences, Kampala, Uganda.
authors.forename: Andrew
authors.initials: A
authors.lastname: Akampurira
authors.affiliation: University of Minnesota, Minneapolis, Minnesota Infectious Disease Institute, Makerere University, Kampala, Uganda.
authors.forename: Joshua
authors.initials: J
authors.lastname: Rhein
authors.affiliation: University of Minnesota, Minneapolis, Minnesota.
authors.forename: Bozena M
authors.initials: BM
authors.lastname: Morawski
authors.affiliation: Infectious Disease Institute, Makerere University, Kampala, Uganda.
authors.forename: Reuben
authors.initials: R
authors.lastname: Kiggundu
authors.affiliation: Infectious Disease Institute, Makerere University, Kampala, Uganda.
authors.forename: Henry W
authors.initials: HW
authors.lastname: Nabeta
authors.affiliation: University of Minnesota, Minneapolis, Minnesota Infectious Disease Institute, Makerere University, Kampala, Uganda Makerere University College of Health Sciences, Kampala, Uganda.
authors.forename: Abdu K
authors.initials: AK
authors.lastname: Musubire
authors.affiliation: University of Minnesota, Minneapolis, Minnesota.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Bahr
authors.affiliation: University of Minnesota, Minneapolis, Minnesota Infectious Disease Institute, Makerere University, Kampala, Uganda.
authors.forename: Darlisha A
authors.initials: DA
authors.lastname: Williams
authors.affiliation: Institute of Infection and Immunity, St. George's University of London, London, UK.
authors.forename: Tihana
authors.initials: T
authors.lastname: Bicanic
authors.affiliation: LAC+USC Medical Center, University of Southern California, Los Angeles, California.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Larsen
authors.affiliation: University of Minnesota, Minneapolis, Minnesota Infectious Disease Institute, Makerere University, Kampala, Uganda Makerere University College of Health Sciences, Kampala, Uganda.
authors.forename: David B
authors.initials: DB
authors.lastname: Meya
authors.affiliation: University of Minnesota, Minneapolis, Minnesota boulw001@umn.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: Boulware
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000134:cerebrospinal fluid / Q000188:drug therapy / Q000382:microbiology; D000328:Adult; D000935:Antifungal Agents / Q000627:therapeutic use; D002555:Cerebrospinal Fluid / Q000382:microbiology*; D005260:Female; D006801:Humans; D057230:Limit of Detection; D008297:Male; D016919:Meningitis, Cryptococcal / Q000134:cerebrospinal fluid* / Q000188:drug therapy / Q000382:microbiology*; D009172:Mycology / Q000379:methods* / Q000592:standards*; D011446:Prospective Studies; D012720:Severity of Illness Index
chemical_list: D000935:Antifungal Agents
keywords: Cryptococcus; HIV/AIDS; accuracy; culture; meningitis; methodology