A Clinical Comparison Between Mycobacterium avium and Mycobacterium intracellulare Infections

A Clinical Comparison Between Mycobacterium avium and Mycobacterium intracellulare Infections* Shigefumi Maesaki , M.D .; Shigeru Kohno, M.D., F.C.C.P.; Hironobu Koga, M.D.; Yoshitsugu Miyazaki, M.D.; and Mitsuo Kaku , M.D. Susceptibility, clinical features, and response to treatment were compared between 29 cases of Mycobacterium aoium infection and 43 cases of Mycobacterium intracellulan infection detected in the Nagasaki Qapan) area and identified by a DNA probe method. In oitro susceptibility of two species to antituberculous agents was determined by a microdilution method, and M aoium was more resistant to enviomycin at 2.5 mgiL than M intracellulan, while M intracellulan was more resistant to isoniazid at 5 mgiL and to cycloserine at 20 mgiL. No significant difference was found between infections caused by two species as to background factors, laboratory data, clinical symptoms, and chest radiographic findings at the onset of the disease. Approximately 70 percent of the patients in each group had underlying diseases; among them, pulmonary tuberculosis was the most common. Negative conversion of bacilli during

the 6-month treatment was seen in 17 of 29 patients (59 percent) with M aoium infection and in 21 of 43 patients (49 percent) with M intracellulan infection. Bacilli-negative conversion was slightly faster in the former than in the latter. However, these differences were statistically not significant. In conclusion, most M aoium-intracellulan complex organisms are clearly identified as M aoium or M intracellulare by the DNA probe method, and there was no significant difference in clinical features and response to treatment between infections caused by the two species.

caused by mycobacteria other than MycoI nfection bacterium tuberculosis (M OTI') has been increas-

culous agents was determined using a microdilution method (Kyokuto Pharmaceutical Co, Tokyo). Tested agents were isoniazid (IN H), ethambutol (EB), rifampin (RFP), para-amino-salicylic acid (PAS), streptomycin (SM), kanamycin (KM), capreomycin (CPM), enviomycin (EVM), ethionamide (TH), and cycloserine (CS). Ogawa egg medium, 0.2 ml of 1 percent, containing different concentrations ofagents was poured into each well of a microdilution plate, and after coagulation and d isinfection, 0.02 ml of bacilli suspension was prepared by suspending a 1 to 3 mg colony in 1 ml sterile distilled water inoculated in each well, with incubation for 37"C for 3 to 4 weeks. Criteria for interpreting results of susceptibility tests are the following: susceptible-no growth on agentcontaining medium; partially resistant-color of agent-containing medium changed to yellow or thin-coat growth of colony on agentcontaining medium; and resistant-thick-coat growth of colony on agent-containing medium. These criteria of clinical resistance are adopted in the "standard method treatment for tuberculosis" in Japan.'

ing in Japan since 1970. Most clinically isolated cases of MarT infections in Japan are caused by M aviumintracellularn complex (MAC), and MAC can now be divided into M avium and M intracellularn using a DNA probe method. Little is known about the possible differences of clinical features and of responses to treatment between infections caused by M avium and M intracellularn. This study is a comparison between two species of identified MAC infection in the Nagasaki Gapan) area, using a DNA probe method, regarding susceptibility to antituberculous agents, clinical features, and response to treatment. MATERIALS AND METHODS

Study Subjects A total of 72 strains of MAC, 29 strains of M avium, and 43 strains of M intraceUulare identified by a DNA probe method (Gen-Probe Rapid Diagnostic System, Gen-Probe Inc, San Diego), isolated from 1983 to 1990, was subjected to the study. In this study, 29 cases of M avium infection were defined as group 1 and 43 cases of M intraceUulare infection were defined as group 2. In Vitro Drug Susceptibility Test The in vitro susceptibility of mycobacteria to various antituber*From the Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan. Manuscript received December 3, 1992; revision accepted March 15, 1993. Reprint requests: Dr. Maesaki , 2nd Department of Internal Medicine, Nagasaki University, Nakamoto 1-7-1 Nagasaki 852, japan

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(CheBt 1993; 104:1408-11) CPM =capreomycin; CS =cycloserine; EB= ethambutol; EVM = enviomycin; INH = isooiazid; KM =kanamycin; MAC= M,cobactniaun ..,;,~re complex; MOTT = mycobacteria other than M tuberculoril; PAS= para-amino-salicylic acid; RFP = rifampin; SM =streptomycin; TH =ethionamide

Clinical Study Background factors such as age, sex, symptoms and laboratory data, chest radiographic findings at detection, and response to treatment were compared. Patients without underlying pulmonary diseases were defined as having primary type, and patients with underlying pulmonary diseases were defined as having secondary type. Statistical Analysis Differences between two species in susceptibility to antituberculous drugs and response to treatment were tested by Fisher's exact test, and differences between two groups in clinical features were compared by Student's t test. RESULTS

In Vitro Susceptibility to Antituberculous Agents

In vitro susceptibility of tested strains to various Comparison of M avium and M intnJcellulare Infections (Maesaki et at)

Table 1-Scuceptibility ofM avium and M intracellulare to Antituberculoua Agenta• Drug,

M avlum (30),

M lntraceUulare (43),

mg!L

No. (%)

No.(%)

p Value

2 (6)

22 (74) 6 (20)

9 (17) 42 (78) 3 (5)

NS

3 (10) 23 (77) 4 (I3)

6 (II) 44 (8I) 4 (8)

NS

I (3) I8 (60) II (37)

0 (O) 50 (92) 4 (8)

<0.01

5 (I7) 20 (66) 5 (17)

I (2) 35 (65) I8 (33)

<0.05

1 (3)

19 (64) IO (33)

2 (4) 29 (54) 23 (42)

NS

1 (3) I9 (64) 10 (33)

0 (0) 47 (87) 7 (I3)

<0.05

I (3) 23 (77) 6 (20)

0 (0) 38 (70) 16 (30)

NS

I (3) 21 (70) 8 (27)

33 (6I) I9 (35)

SM , 20

s

R

KM,25

s

R

EVM , 25

s

I

R INH , S

s

I

R

EB,S

s I

R RFP, 10

s

I

R PAS,10

s I

R

TH,25

s

I

R

2 (4)

NS

CPM , 25

s

I

R

1 (3)

I7 (57) I2 (40)

0 (O) 43 (80)

I

R

3 (10) 25 (83) 2 (7)

NS

II (20) 0

M avium

M lntraceUulare

Male, No. (%) Female, No. (%) Age, yr No. ofWBC, /mm3 Neutrophils, % ESR, mmlh CRP Symptom, No. (%) No symptom Sputum Cough Fever Hemoptysis Dyspnea Weight loss

12 (4I) I7 (59) 66±10.ot 6,160± I,850t 66.4±9.21t Sl.l ±33.4t l.l4± l.02t

26 (60) 17 (40) 63.9±ll .7t 7,602± 1,949t 66.8±I2.4t 5l.l±37.2t 1.39± l.29t

14 9 8 4 3 1 1

(48) (31) (28) (14) (IO) (4) (4)

15 I2 II ll 10 2 1

(35) (28) (26) (26) (22) (5) (2)

*CRP = C-reactive protein; ESR =erythrocyte sedimentation rate. tMean±SD.

rocyte sedimentation rate, and C-reactive protein. As shown in Table 3, pulmonary tuberculosis was most commonly seen as underlying disease, and a pattern of underlying diseases was similar in both groups. Chest radiographic findings in both groups are presented in Table 4. Cavitary disease was seen in 82 percent of group 1 and 72 percent of group 2, and type of pulmonary lesions as well as cavities were similar in both groups. Fibrocaseous type was seen slightly more in group 1; however, the difference was insignificant. Response to treatment was followed up for the Table 3-Underlging DUea.ea ofM avium and M intracellulare Infection

(O)

42 (77) I2 (23)

Characteristic

Response to 'Ireatment

CS,20

s

Table 2-Comparison of Clinical Characteriatica of M avium and M intracellulare lnfoction•

<0.05

•s =susceptible;

I= intermediate; R=resistant; SM = streptomycin; KM =kanamycin; EVM = enviomycin; INH =isoniazid; EB =ethambutol; RFP = rifampin; PAS= para-amino-salicylic acid; TH =ethionamide; CPM = capreomycin; CS =cycloserine; NS =not significant.

antituberculous drugs is shown in Table 1. Most strains of two species were resistant to all antituberculous agents, and a susceptibility pattern was similar in both species except M avium was more resistant to EVM and M intracellulare was more resistant to INH and

cs.

Clinical Features

Clinical features of groups 1 and 2 are presented in Table 2. The ratio of male to female subjects was slightly higher in group 2. No significant difference was found between groups as to age distributions, number of WBCs, proportion of neutrophils, eryth-

Underlying Diseases• Primary infection Secondary infection Pulmonary tuberculosis Thoracoplasty Pneumoconiosis Bronchiectasis Emphysema Pulmonary fibrosis Chronic bronchitis Empyema Hypertension Diabetus mellitus Malignancy Liver diseases Cerebral infarction Gastric ulcer Rheumatoid arthritis Heart failure

M avlum,

M lntraceUulare,

No. (%)

No. (%)

8 2I 18 3 3 2 2

(28) (72) (62) (10) (10)

13 (30) 30 (70)

1

(3)

(7) (7) (3)

0 4 0 I 2 2 2 0 0

(14) (3)

(7) (7) (7)

24 (56)

(7)

3 1 5 1 I

(2) (I2) (2) (2)

1

(2)

1 (2) 3 (7) 3 (7) 2

(5)

(2) (2) 0 1 (2) (2)

*Primary infection =without underlying pulmonary diseases; secondary infection = with underlying pulmonary diseases. CHEST I 104 I 5 I NOVEMBER, 1993

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Table 5-&cilli-Negatit¥ Cmwertion Bate in Prima'll tmd Secontlmy 1)/pea cfM aviwn and M intracellulare

Table 4-Chat &diograplaic Findinga in M aviwn and M intraceUulare Infection Finding of Shadow Right side Left side Bilateral Noncavitary shadow Exudative Infiltrative-caseous Fibrocaseous Fibrotic Mixed Cavitary• Thin-walled (infiltrative) Thin-walled (fibrotic) Thiclc-walled (infiltrative) Thiclc-walled (fibrotic) Multiple (infiltrative) Multiple (fibrotic)

M twium, No.(._,)

M jntracellulare, No.(._,)

11 (38) 6 (21) 12 (41)

13 (30) 11 (25) 19 (45)

0 9 (31) 18 (62)

0 2

m

24 (82) 0 1 (4) 7 (29) 6 (25)

0 10 (46)

3

lnfoction*

Primary Type

m

18 (41) 19 (44)

1 (2) 2 (6) 31 \12) 2 (6) 3 (10)

..,

No.

obs

(-) con

..,

No. obs

(-) con

..,

8

5

63

21

12

57

29

17

59

13

5

37

30

16

53

43

21

49

21

10

48

51

28

55

72

38

53

of MAC

obs

Mtwium infection M UatnJcelltJare infection

1btal

Total

con

(-)

No.

Species

Secondary Type

•No. obs =number of patients observed; (-) con= number of negatM: conversion. MAC= Mycobocterium IJVium-jntracellulare complex. DISCUSSION

12 (37) 5 (16) 3 (10) 6 (21)

Mycobacterium avium infection was seen predominantly in the eastern part, while M intraceUulare infection was seen predominantly in the western part of Japan. Nagasaki is situated in the most western part of Japan, and in this study, M intraceUulare infection occupied 60 percent of whole MAC cases; this fact coincides with the national trend reported by Saito et

~e thickness of cavity wall: thin-walled= 2 mm or less; ~­

walled= thicker than 2 mm.

initial6 months. As shown in Thble 5, bacilli-negative conversion rate was 59 percent in group 1 and 49 percent in group 2; however, the difference was insignificant. Speed of negative conversion was compared between two groups, and as shown in Thble 6, patients in group 1 converted to negative within 4 months, while a few patients in group 2 converted to negative in the late initial period of treatment. As most patients in both groups were treated initially with the combination of INH, RFP, and EB on diagnosis of M tuberculosis infection, and SM or KM and/or quinolones were introduced mainly in patients with contained bacilli discharge, it is hardly possible to evaluate a role of each antituberculous agent in bacilli-negative conversion. Among patients treated with the combination ofiNH, RFP, and EB throughout the initial 6 months, bacilli-negative conversion rate was 62 percent in group 1 and 49 percent in group 2; however, the difference was insignificant again as the number of patients in both groups was so small.

al.2

Clinical cases of MAC infection were found mainly in the aged population, and pulmonary tuberculosis

was most common among the underlying diseases. Chest radiographic findings were characterized by cavity formation. Proportions of female and of fibrocaseous-type lesions were slightly higher in group 1 than in group 2, and further studies are needed to confirm whether the difference is significant or is seen by chance. Tomioka et al,3 using 7Hll agar plate method, reported that M avium was much more resistant to RFP and rifabutin than M intraceUulare. In this study, resistance to RFP was slightly higher in M avium; however, the difference was insignificant. Tsukamura et al4 reported that KM and EVM were more active against MAC than M tuberculosis. In our in vitro study, SM, .KM, and EVM were more active against both species than other agents. In this study, four

Table 6- Tame for Negatiw Convenion During 6-Month 'lmltmmt* Months After Starting Treatment 1 M twium infection

(29 cases)

M jntracellulare infection (43 cases)

Negative converted Cumulative number ._, to total 29 ._,to 17(-)con Negative converted Cumulative number ._, to total 43 ._, to 21 (-) con

•(-) con= number of negative converted cases.

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3 3 10 18 4 4 9 19

2

3

4

8

1 12 41 71 6 18 42

5 17 100 1 19 44

86

90

11 38 65 8 12

28 57

5

6

1 20 47 95

1 21 49 100

59

subjects treated from the beginning with a fouNlrug combination of INH, RFP, EB, and SM or KM ~nverted to negative. The fact suggests that better treatment results might be achieved by adding SM or other aminoglycoside agents from the very beginning of treatment. Engbaek et al5 and Simoide6 reported that the efficacy of CS against M intraceUulare infection was similar to other antituberculous agents. In our clinical study, CS was not used as it is not an agent of first choice even in MAC infection due to high incidence of severe side effects. Our previous report7 and that of Leonid and Pamela8 indicated the clinical efficacy of new quinolones against M tuberculosis and MOTT infection. In our study, four patients in group 1 treated with the combination of INH, RFP, EB, and quinolone (two patients each with ofloxacin and sparfloxacin} and two patients in group 2 treated with the combination of INH, RFP, and ofloxacin converted to negative in the first 2 to 3 months of treatment. As MOTT infection, in particular MAC infection, has been increasing in Japan, we need to cope with this situation appropriately by (1} rapid identification of mycobacterial species by DNA probe, (2} selection of appropriate regimen of chemotherapy for MOTT infection, and (3} search for new effective agents for MAC. ACKNOWLEDGMENT: The authors would like to express appreciation to Prof. K. Hara for his excellent guidance and contribution

to this study. We express appreciation to Dr. T. Shimada for helpful comments on the manuscript. We also wish to acknowledge cooperation of staffs in co-study hospitals and their microbiologic laboratories. REFERENCES 1 An investigation by the tuberculosis research committee (Ryokcn) Japan. Primary drug resistance to the major antituberculosis in Japan. Tubercle 1970; 51:152-71 2 Saito H. Tomioka H, Sato K, Thsaka H. Tsukamura M, Kuze F, et al. Identification and partial characterization of Mycobacterium avium and Mycobocterium intraceUulare by using DNA probes. J Clin Microbiol1989; 27:994-97 3 Tomioka H, Sato K, Saito H, Yamada Y. Susceptibility of Mycobocterium avium and Mycobocterium intraceUulare to various antibacterial drugs. Microbiol Immunol1989; 33:509-14 4 Tsukamura M, Ichiyama S, Miyachi T. Relationship between the susceptibility testing of Mycobacterium avium complex strains and the clinical efficacy of antituberculosis drugs. Kekkaku 1988; 63:227-31 5 Engbaek HC, Vergmann B, Bentzon MW. Lung disease caused by Mycobacterium avium/Mycobacterium lntraceUulare: an analysis of Danish patients during the period of 1962-1976. Eur J Respir Dis 1981; 62:72-83 6 Simoide H. Clinical s~dy on atypical mycobacteriosis: report 13, results of treatment of pulmonary diseases due to Mycobacterium lntraceUulare by multiple (four or five) drug regimen. Jpn J Chest Dis 1981; 40:669-76 7 Kohno S, Koga H, Kaku M, Maesalci S, Hara K. Prospective comparative study of ofloxacin or ethambutol for the treatment of pulmonary tuberculosis. Chest 1992; 102:1815-18 8 Leonid BH, Pamela JLL. Bacteriostatic and bactericidal activity of ciproftoxacin and oftoxacin against Mycobocterium tuberWrU and Mycobacterium avium complex. Tubercle 1987; 68:267-76

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