title: [Isolation rate of Mycobacterium tuberculosis complex from patients with suspected tuberculosis and identification of the strains with BACTEC™ NAP and immunochromatographic TB Ag MPT64 Rapid™ Tests].
abstract: Tuberculosis (TB) which is still one of the important infectious diseases in the world as well as Turkey, results in high morbidity and mortality. Clinical mycobacteriology laboratories have crucial roles in the identification, typing and susceptibility testing of Mycobacterium tuberculosis. The aims of this study were the investigation of the isolation rate of M.tuberculosis complex (MTC) from the clinical specimens of TB-suspected patients and to compare identification of mycobacteria isolated from solid and/or liquid media by using BACTEC NAP and immunochromatographic TB Ag MPT64 rapid test. A total of 1670 patients who were admitted to outpatients clinics of our hospital and prediagnosed as TB, have been included in the study. All the patients were anti-HIV seronegative. NALC-NaOH method were used for decontamination/ homogenization, and preparations from samples were stained with Erlich-Ziehl-Neelsen method to detect acid-resistant bacilli (ARB) in direct microscopy. All of the samples were inoculated into BACTEC™ MGIT-960 (Becton Dickinson, USA) and Löwenstein-Jensen (LJ) media for cultivation and incubated at 37°C for 6-8 weeks. Mycobacteria that were grown in the media have been identified by BACTEC™ NAP (Becton Dickinson, USA) and TB Ag MPT64 rapid test (SD Bioline Ag MPT64 Rapid™; Standard Diagnostics, Korea). The culture positivity in the samples of TB-suspected patients was found to be 3.7% (63/1670) with LJ and/or MGIT-960 methods, whereas ARB positivity rate was 1.6% (28/1670). Fifty-three (84%) out of culture positive 63 samples have been identified as MTC by BACTEC NAP test, while 61 (97%) were found as MTC by TB MPT64 test. Considering BACTEC NAP test as the reference method, TB MPT64 test identified all the MTC strains correctly (sensitivity: 100%), however the false positivity rate was estimated as 12.7% (specificity: 87%). Of 53 MTC positive samples, 36 were sputum, four were bronchoalveolar lavage, four were urine, three were gastric fluid, three were pleural fluid, and one of each were abscess, peritoneal fluid and cerebrospinal fluid samples. ARB positivity rate was detected as 41.5% (22/53) among MTC culture positive samples. Of the patients who were infected with MTC, 72% (38/53) were male and 98% (52/53) were adults (age range: 20-85 years). Our data indicating 3.1% (53/1670) isolation rate of MTC from TB-suspected patients in our region were in concordance with the other results reported from Turkey. In conclusion, immunochromatographic TB Ag MPT64 test which seemed to be useful for the rapid identification of mycobacteria grown on solid and/or liquid, was practical to perform and had high sensitivity, however further larger-scaled studies are needed to support our data in our country.
authors.affiliation: Konya Training and Research Hospital, Central Laboratory, Konya, Turkey. kurtoglumg@hotmail.com.
authors.forename: Muhammet Güzel
authors.initials: MG
authors.lastname: Kurtoğlu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozdemir
authors.forename: Recep
authors.initials: R
authors.lastname: Keşli
authors.forename: Birol
authors.initials: B
authors.lastname: Ozkalp
authors.forename: Bülent
authors.initials: B
authors.lastname: Baysal
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015373:Bacterial Typing Techniques / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology*; D014421:Turkey / Q000453:epidemiology; D055815:Young Adult