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Volume 12, Number 5—May 2006
THEME ISSUE
Tuberculosis Special Section

Research

Mycobacterium tuberculosis and Rifampin Resistance, United Kingdom

I-Ching Sam*1, Francis Drobniewski*Comments to Author , Philip More*, Melanie Kemp*, and Timothy Brown*
Author affiliations: *Health Protection Agency, London, United Kingdom

Main Article

Table 1

Results of LiPA compared with culture in detecting MTBC in primary clinical specimens*

Sample and AFB smear result No. positive/no. tested (%)
Concordance Sensitivity Specificity PPV NPV Mean days saved
All primary LiPA 1,667/1,922 (86.7) 782/918 (85.2) 886/1,004 (88.2) 782/900 (86.9) 886/1,022 (86.7) 15.2
Positive 960/1,099 (87.4) 747/798 (93.6) 213/301 (70.8) 747/835 (89.5) 213/264 (80.7) 14.8
Negative 679/792 (85.7) 35/119 (29.4) 644/673 (95.7) 35/64 (54.7) 644/728 (88.5) 22.1
Not done 28/31 (90.3) 0/1 (0) 29/30 (96.7) 0/1 (0) 29/30 (96.7)
All primary LiPA (adjusted values)† 1,667/1,828 (91.2) 782/918 (85.2) 886/921 (96.2) 782/817 (95.7) 886/1,022 (86.7) 15.2
Positive 960/1,028 (93.4) 747/798 (93.6) 213/232 (91.8) 747/766 (97.5) 213/264 (80.7) 14.8
Negative 679/771 (88.1) 35/119 (29.4) 644/659 (97.7) 35/50 (70.0) 644/728 (88.5) 22.1
Not done 28/29 (96.6) 0/1 (0) 29/30 (96.7) 0/1 (0) 29/30 (96.7)
Respiratory 1,168/1,298 (90.0) 672/738 (91.1) 496/560 (88.6) 672/736 (91.3) 496/562 (88.3) 14.7
Positive 827/915 (90.4) 657/696 (94.4) 170/219 (77.6) 657/706 (93.1) 170/209 (81.3) 14.5
Negative 328/369 (88.9) 15/42 (35.7) 313/327 (95.7) 15/29 (51.7) 313/340 (92.1) 20.5
Not done 13/14 (92.9) 13/14 (92.9) 0/1 (0.0) 13/13 (100.0)
Nonrespiratory 499/624 (80.0) 110/180 (61.1) 390/444 (87.8) 110/164 (67.1) 390/960 (84.8) 18.3
Positive 133/184 (72.3) 90/102 (88.2) 43/82 (52.4) 90/129 (69.8) 43/55 (78.2) 17.2
Negative 351/423 (83.0) 20/77 (26.0) 331/346 (95.7) 20/35 (57.1) 331/388 (85.3) 23.4
Not done 15/17 (88.2) 0/1 (0) 16/16 (100.0) 16/17 (94.1) –-
Biopsy specimen‡ 92/108 (85.2) 13/26 (50.0) 79/82 (96.3) 13/16 (81.3) 79/92 (85.9) 22.4
Positive 19/21 (90.5) 10/10 (100.0) 9/11 (81.8) 10/12 (83.3) 9/9 (100.0) 24.1
Negative 72/86 (83.7) 3/16 (18.8) 69/70 (98.6) 3/4 (75.0) 69/82 (84.1) 16.7
Not done 1/1 (100.0) 1/4 (25.0) 1/1 (100.0)
Gastric aspirate 17/18 (94.4) 4/5 (80.0) 13/13 (100.0) 4/4 (100.0) 13/14 (92.9) 16.8
Positive 8/8 (100.0) 4/4 (100.0) 4/4 (100.0) 4/4 (100.0) 4/4 (100.0) 16.8
Negative 9/10 (90.0) 0/1 (0.0) 9/9 (100.0) 9/10 (90.0)
Not done
Lymph node 103/142 (72.5) 50/68 (73.5) 53/74 (71.6) 50/71 (70.4) 53/71 (74.6) 18.7
Positive 54/79 (68.4) 42/48 (87.5) 12/31 (38.7) 42/61 (68.9) 12/18 (66.7) 16.6
Negative 48/62 (77.4) 8/20 (40.0) 40/42 (95.2) 8/10 (80.0) 40/52 (76.9) 29.6
Not done 1/1 (100.0) 1/1 (100.0) 1/1 (100.0)
Pleural fluid 84/107 (78.5) 5/23 (21.7) 79/84 (94.0) 5/10 (50.0) 79/97 (81.4) 26.8
Positive 6/10 (60.0) 4/5 (80.0) 2/5 (40.0) 4/7 (57.1) 2/3 (66.7) 23.5
Negative 77/97 (79.4) 1/18 (5.6) 76/78 (97.4) 1/3 (33.3) 76/93 (81.7) 40.0
Not done 1/1 (100.0) 1/1 (100.0) 1/1 (100.0)
Psoas abscess 8/15 (53.3) 3/6 (50.0) 5/9 (55.6) 3/7 (42.9) 5/8 (62.5) 19.0
Positive 2/3 (66.7) 2/2 (100.0) 0/1 (0.0) 2/3 (66.7) 17.0
Negative 6/12 (50.0) 1/4 (25.0) 5/8 (62.5) 1/4 (25.0) 5/8 (62.5) 23.0
Not done
Vertebral aspirate 26/30 (86.7) 10/12 (83.3) 16/18 (88.9) 10/12 (83.3) 16/18 (88.9) 15.4
Positive 9/10 (90.0) 8/8 (100.0) 1/2 (50.0) 8/9 (88.9) 1/1 (100.0) 14.5
Negative 17/19 (89.5) 2/3 (66.7) 15/16 (93.8) 2/3 (66.7) 15/16 (93.8) 19.0
Not done 0/1 (0.0) 0/1 (0.0) 0/1 (0.0)
Other§ 169/204 (82.8) 25/40 (62.5) 145/164 (88.4) 25/44 (56.8) 145/160 (90.6) 15.2
Positive 35/53 (66.0) 20/25 (80.0) 15/28 (53.6) 20/33 (60.6) 15/20 (75.0) 15.1
Negative 122/138 (88.4) 5/15 (33.3) 117/123 (95.1) 5/11 (45.5) 117/127 (92.1) 15.8
Not done 12/13 (92.3) 13/13 (100.0) 13/13 (100.0)

*MTBC excludes 75 specimens containing substances inhibitory to the polymerase chain reaction (PCR), PCR-equivocal results, and samples with no definitive culture results (i.e., contaminated or not done). LiPA, line probe assay; MTBC, Mycobacterium tuberculosis complex; AFB, acid-fast bacilli; PPV, positive predictive value; NPV, negative predictive value.
†Excludes samples from patients with a microbiologic diagnosis of MTBC made at the Mycobacterium Reference Unit in the last 18 or subsequent 3 months, and patients receiving antituberculous treatment currently or within the last 3 months.
‡Includes biopsy specimens from liver (n = 13), kidney (n = 2), skin (n = 15), lung (n = 20), pleura (n = 13), and miscellaneous sites (n = 45).
§Includes ascites (n = 56), pericardial aspirates (n = 29), aspirates from miscellaneous sites (n = 80), blood (n = 1), bone marrow (n = 22), feces (n = 1), and urine (n = 15).

Main Article

1Current affiliation: University of Malaya, Kuala Lumpur, Malaysia

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