[雙語翻譯]外文翻譯-分枝桿菌基因型直接檢測(cè)痰標(biāo)本對(duì)檢測(cè)結(jié)核分枝桿菌復(fù)合體的評(píng)價(jià)（原文）

1、Evaluation of the GenoType Mycobacteria Direct assay for direct detection of the Mycobacterium tuberculosis complex obtained from sputum samplesNuri Kiraz, Imran Saglik, Abdurrahman Kiremitci, Nilgun Kasifoglu and Yurdan

2、ur AkgunCorrespondenceNuri Kiraznkiraz@ogu.edu.trReceived 10 June 2009Accepted 1 May 2010Eskisehir Osmangazi University, Faculty of Medicine, Department of Microbiology, Eskisehir, TurkeyAn increase in the prevalence of

3、tuberculosis (TB) in recent years has accelerated the search fornovel tools for the rapid diagnosis of TB infection. This study evaluated the GenoTypeMycobacteria Direct (GTMD) assay (Hain Lifescience) for direct detecti

4、on of the Mycobacteriumtuberculosis complex (MTBC) from sputum samples and compared it with conventional methods.The GTMD test is a commercial assay produced using strip techniques and works based on anucleic acid sequen

5、ce-based amplification technique. This test allows 23S rRNA amplification-based detection of MTBC, Mycobacterium avium, Mycobacterium intracellulare, Mycobacteriumkansasii and Mycobacterium malmoense directly from decont

6、aminated clinical samples within6 h. In the present study, 115 sputum samples were processed to detect acid-fast bacilli (AFB)using two microscopy methods (carbol fuchsin and fluorescent staining), two culture methods[Lo

7、 ¨wenstein–Jensen (LJ) and BACTEC 12B media] and the GTMD test. The results showed that86 of the samples were positive by direct microscopy, 84 were positive by BACTEC 12B culture,73 were positive by LJ culture and

8、95 were positive by the GTMD test. All of the isolates turnedout to be MTBC. Moreover, the sensitivity and specificity of the GTMD test for MTBC in patientswere 97 and 58 %, respectively, taking the culture combination a

9、s the gold standard. When thetest was compared with culture of samples from anti-TB-treated patients, the sensitivity andspecificity for the test were 100 and 15 %, respectively. Low specificity in treated people mightar

10、ise from depressed proliferation of AFB. As the two methods target the same living bacilli, thedifference is obviously notable. When the culture results and clinical findings of the patients wereevaluated together (true-

11、positive specimens), the sensitivity and specificity values of the GTMDtest for all patients were 97 and 90 %, respectively. However, both of these values increased to100 % for the patients receiving anti-TB treatment. T

12、hese results implied that, to determinewhether the patient’s sputum contains living AFB, more sensitive techniques should be employedduring the follow-up of the patients. These observations suggest that the GTMD method c

13、an beuseful for early diagnosis of clinically and radiologically suspicious TB cases where smears arenegative for Mycobacterium. In addition, the use of a GTMD test in smear-positive cases is helpfuland practical in orde

14、r to identify MTBC quickly. This allows more rapid treatment decisions andinfection control precautions.INTRODUCTIONTuberculosis (TB) remains an important community health problem. The World Health Organization estimates

15、 that 8 million new TB cases are reported annually and are the cause of death in 2–3 million patients. Each untreated pulmonary TB patient is responsible for the spread of thedisease to 10–15 humans over a year. This mak

16、es TB one of the most important causes of death from an infectious agent (Corbett et al., 2003; WHO, 2007).The most effective means of protection is early diagnosis and treatment of the disease. Preliminary diagnosis is

17、based on clinical findings, but definite diagnosis is by laboratory methods (Drobniewski et al., 2003).The gold standard test in the diagnosis of TB is culture, but biochemical tests used in identification of the species

18、 areAbbreviations: AFB, acid-fast bacilli; GI, growth index; GTMD, GenoType Mycobacteria Direct; NPV, negative predictive value; PPV, positive predictive value; TB, tuberculosis.Journal of Medical Microbiology (2010), 59

19、, 930–934 DOI 10.1099/jmm.0.013490-0930 013490 G 2010 SGM Printed in Great Britainfor each patient. When we inspected the homogenized decontaminated sputum sample smears, we detected AFB in 86 and 66 samples using the fl

20、uorescent and carbol fuchsin staining procedures, respectively. As all of the samples positive for AFB by carbol fuchsin staining were also positive by fluorescent staining, we used the results of fluorescent staining of

21、 smears prepared from homogenized decontaminated sputum samples for evaluation of direct microscopic examination. Carbol fuchsin staining results indicated that, whilst 15 of the 66 samples were negative for AFB growth i

22、n direct sputum samples, all 66 smears prepared from homogenized decontaminated sputum samples were positive for AFB growth. Similarly, although the 86 smears prepared from homogenized decontami- nated sputum samples wer

23、e positive for AFB growth with fluorescent staining, 10 of these smears prepared from direct sputum samples were negative for the presence of AFB. Following examination of these different samples, we described the number

24、 of bacteria in smears prepared from homogenized and decontaminated sputum samples as ‘+’ for a few bacteria and ‘++’ for moderate numbers of bacteria. Thus, the present findings indicated that AFB growth may not be dete

25、cted in direct smears that have only a few bacteria. Moreover, whilst there were only a few AFB (‘+’) in direct smears stained with carbol fuchsin and prepared from small amounts of sputum, staining was negative for AFB

26、in smears prepared from homogenized decontaminated sputum. This observation implied that the preparation of direct smears from sputum samples often fails to detect the growth of AFB and may be a waste of time and work fo

27、rce. However, the preparation of direct smears may be useful for small amounts of sputum samples, as the homogenization and decontamination procedures dilute the sample and lead to the loss of AFB.A comparison of the sta

28、ining and culture methods is shown in Table 1. With fluorescent staining, we detected AFB in seven out of 31 sputum samples that did not show any growth. These seven sputum samples were obtained from patients who were un

29、der anti-TB treatment. Whencompared with culture, the sensitivity and specificity of fluorescent staining were 94 and 77 %, respectively.A comparison of the GTMD test results and direct microscopy is also illustrated in

30、Table 1. There were two GTMD-negative samples that were positive for fluorescent staining. One of these samples was obtained from a patient under anti-TB treatment and the bacterial density for this sample was determined

31、 as ‘+’; this sample did not show growth in culture. We concluded that the positivity in direct microscopic inspection of this sample could have been due to the presence of dead bacteria. Likewise, the bacterial density

32、for the other sample was determined as ‘+’. This sample was taken from a patient not receiving anti-TB treatment and showed growth in culture within 18 days (BACTEC 12B medium). As we observed an internal control amplifi

33、cation band on the GTMD test strip, the presence of an inhibitor in the sample was not considered and the result was interpreted as a false-negative for the GTMD test. When compared with direct micro- scopic inspection,

34、the sensitivity, specificity and positive predictive value (PPV) and negative predictive value (NPV) of the GTMD test were established as 98, 62, 88 and 90 %, respectively.Eighty-four and 73 sputum samples were found to

35、be positive in BACTEC 12B vials and LJ medium, respectively. All growth patterns on LJ medium were concordant with those of MTBC (light-cream coloured, rough, breadcrumb- like colonies). All AFB growing in BACTEC 12B med

36、ium were identified as MTBC by the NAP test. In addition, 82/ 84 culture-positive sputum samples were also verified as GTMD-positive (Table 1). The remaining two samples were culture-positive but GTMD-negative. One of th

37、ese with no detectable band on the GTMD test strip was interpreted as negative following direct microscopic inspection. The negativity of this sample for the GTMD test may have been due to the presence of only a few bact

38、eria. Similarly, the bacterial density for the other sample following direct microscopic inspection was determined as ‘+’; this sample was taken from a patient receiving no anti-TB treatment. As we detected an internal c

39、ontrol amplification band on GTMD test strip, the occurrence of an inhibitor in the sample was not considered and the result was interpreted as false-negative for the GTMD test due to presence of only a few bacteria. Mor

40、eover, 13 sputum samples showing no growth in the culture were positive for the GTMD test; 11 of these were obtained from patients under anti-TB treatment and with six of these we detected AFB following direct microscopi

41、c assessment. The other two of the 13 sputum samples (no growth in culture but positive for the GTMD test) were AFB-negative and were taken from patients not receiving anti-TB treatment at the time of sampling and diagno

42、sed with different lung diseases. However, no medical history was taken regarding TB infection for these two patients. When compared with culture, the sensitivity, specificity, PPV and NPV of the GTMD test were 97, 58, 8

43、6 and 90 %, respectively. When the culture results and clinical findings ofTable 1. Test results for the 115 patients in this studyCulture was carried out using BACTEC 12B or LJ medium.Culture-positive(n584)Culture-negat

44、ive(n531)GTMD-positiveGTMD-negativeGTMD-positiveGTMD-negativeSmear-positive (n586)* 78 1 6 1Smear-negative (n529)* 4 1 7 17Total (n5115) 82 2 13 18*Homogenized, decontaminated fluorescent staining.N. Kiraz and others932