Previous Article | Next Article 
Antimicrobial Agents and Chemotherapy, January 2009, p. 316-318, Vol. 53, No. 1
0066-4804/09/$08.00+0 doi:10.1128/AAC.01302-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Susceptibility of Mycobacterium bovis BCG Vaccine Strains to Antituberculous Antibiotics
Nicole Ritz,1,2,3
Marc Tebruegge,1,2,3
Tom G. Connell,1,2,3
Aina Sievers,4
Roy Robins-Browne,1,3,5 and
Nigel Curtis1,2,3*
Department of Paediatrics, The University of Melbourne, Parkville, Australia,1
Infectious Diseases Unit, Department of General Medicine, Royal Children's Hospital Melbourne, Parkville, Australia,2
Murdoch Children's Research Institute, Parkville, Australia,3
Victorian Infectious Diseases Reference Laboratories, North Melbourne, Australia,4
Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia5
Received 29 September 2008/
Returned for modification 8 October 2008/
Accepted 20 October 2008

ABSTRACT
Mycobacterium bovis BCG is one of the most commonly administered
vaccines. Complications, including disseminated BCG disease,
are rare but increasingly reported in immunodeficient children.
There is growing recognition of the importance of differences
between BCG vaccine strains. We determined the susceptibilities
of five genetically distinct BCG vaccine strains to 12 antituberculous
drugs.

INTRODUCTION
Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine
is one of the most commonly administered vaccines worldwide.
It is a live attenuated vaccine derived from
M. bovis, and for
historical reasons a number of genetically different BCG vaccine
strains are in use today (
3,
17). In immunocompetent individuals
local adverse reactions such as injection site abscess and lymphadenitis
occur in less than 1% of vaccinees (
21) and disseminated BCG
disease is extremely rare (
12). However, in individuals with
congenital or acquired immunodeficiency the risk of local complications
and disseminated BCG disease after immunization is considerably
greater (
7). Recent reports from regions with a high prevalence
of human immunodeficiency virus suggest that BCG-related complications
are becoming increasingly common (
7). The appropriate treatment
of local adverse reactions and disseminated BCG disease remains
controversial, and the influence of the particular BCG vaccine
strain or its susceptibility pattern is not considered (
6,
8,
9). There are only limited data on the susceptibility of BCG
to different antituberculous drugs and even less on the influence
of genetic differences between BCG vaccine strains on susceptibility.
BCG vaccine strains were kindly provided by their manufacturers as follows: BCG-Bulgaria (SL 222 Sofia), BB-NCIPD Ltd., Sofia, Bulgaria; BCG-Denmark (SSI 1331), Statens Serum Institute, Copenhagen, Denmark; and BCG-Japan (Tokyo 172) Japan BCG Laboratory, Tokyo, Japan. BCG-Connaught (Sanofi Pasteur, Toronto, Canada) and BCG-Medac (RIVM from 1173-P2; Medac, Hamburg, Germany) were purchased. Freeze-dried BCG vaccine strains were dissolved in 0.5 ml of 0.9% saline (10 ml for BCG-Medac) and cultured using the MB/BacT system (Biomérieux, Durham, NC) according to manufacturer's instructions and subsequently subcultured on solid media (Lowenstein-Jensen and Brown & Buckle agar) for antimicrobial susceptibility testing. Susceptibility testing was done using the Bactec MGIT (mycobacterial growth indicator tube) 960 system (Becton Dickinson, MD) according to the manufacturer's instructions. Lyophilized streptomycin, isoniazid, rifampin (rifampicin), and ethambutol (Bactec MGIT SIRE kit; Becton Dickinson, MD) were each reconstituted and used according to the manufacturer's instructions. Amikacin, capreomycin, ethionamide, kanamycin, and ofloxacin (all Sigma), ciprofloxacin (Bayer), and rifabutin (Farm Italia, Carlo Erba, Research Laboratories) were dissolved and used at the recommended concentrations (Table 1) (11). For susceptibility testing of all drugs except pyrazinamide, the drug-containing tubes were inoculated with a suspension prepared from the culture on solid media and adjusted to a 0.5 McFarland standard in turbidity. The tubes were incubated and monitored for growth until the results indicating susceptibility or resistance were automatically interpreted by the BACTEC MGIT 960 instrument. Susceptibility to pyrazinamide was tested using Wayne's indirect method, measuring the presence of pyrazinamidase (22).
The individual BCG vaccine strains were flagged positive after
the following durations of culture: 2.5 days, BCG-Medac; 2.7
days, BCG-Japan; 4.0 days, BCG-Connaught; 5.2 days, BCG-Denmark;
and 6.2 days, BCG Bulgaria. Results for the testing of susceptibilities
to different antituberculous drugs are shown in Table
1.
This is the first study to compare the susceptibilities of the most commonly used BCG vaccine strains worldwide to a wide range of antituberculous drugs. Previous studies in this area have been limited by the use of a single BCG strain (5) or alternatively by the limited range of antituberculous drugs tested (summarized in Table 2).
View this table:
[in this window]
[in a new window]
|
TABLE 2. Susceptibilities of different BCG vaccine strains to antituberculous drugs using different methods of susceptibility testing
|
Broth-based susceptibility testing using nonradiometric systems,
such as the Bactec MGIT 960 system, are now widely used for
susceptibility testing of mycobacteria, and the correlation
between in vitro testing at a critical antibiotic concentration
and clinical outcome is well documented for
Mycobacterium tuberculosis (
18). Although the correlation between in vitro susceptibility
results and clinical outcome has not been studied for BCG disease,
susceptibility results obtained by this method are considered
clinically relevant as
M. tuberculosis and BCG both belong to
the
M. tuberculosis complex.
Three of the five tested BCG vaccine strains (BCG-Bulgaria, BCG-Japan, and BCG-Medac) were susceptible to all antituberculous drugs except pyrazinamide, to which M. bovis and consequently all BCG vaccine strains are intrinsically resistant.
BCG-Connaught and BCG-Denmark both showed low-level resistance to isoniazid. Resistance of BCG-Denmark to isoniazid is documented by the vaccine manufacturer (Statens Serum Institute; www.ssi.dk/sw10375.asp, 1993), but the clinical significance of this resistance is unclear. The Global Advisory Committee of Vaccine Safety of the World Health Organization reported five patients with isoniazid-resistant BCG lymphadenitis after immunization with BCG-Denmark but concluded that the identification of low-level isoniazid resistance does not justify any change in BCG immunization policy (23). In addition, serum concentrations in children after a dose of 10 mg/kg of body weight isoniazid significantly exceed 0.4 µg/ml (19), suggesting that low-level resistance may not be clinically significant.
Resistance of BCG-Connaught and BCG-Denmark to ethionamide has not previously been documented. The association between resistance to isoniazid and ethionamide is found in other mycobacteria. It was first described for isolates of M. tuberculosis from patients who had been on isoniazid monotherapy, suggesting that isoniazid and ethionamide share a common target (10). Subsequently, the gene inhA, whose mutation or overexpression leads to resistance against isoniazid and ethionamide, was identified in Mycobacterium smegmatis (2). A recent study found that all M. tuberculosis isolates with low-level isoniazid resistance that were also ethionamide resistant had mutations in the regulatory region of the inhA gene (1). In contrast, only 5.9% of isolates with high-level isoniazid resistance that were also ethionamide resistant had such mutations.
In some countries ethionamide is the preferred drug to be included in combination treatment of tuberculous meningitis and is used in cases of disseminated BCG disease with presumed central nervous system involvement. However, if the vaccine strain used for immunization was BCG-Connaught or BCG-Denmark, then our data suggest that an alternative treatment strategy should be used.
We were unable to test susceptibility to erythromycin, as clinically meaningful concentrations of macrolides for in vitro susceptibility testing are not available for M. tuberculosis or M. bovis. Treatment with erythromycin is controversial but is frequently recommended for localized complications after BCG immunization despite limited evidence of efficacy (6). However, in vitro evidence suggests that BCG vaccine strains that have lost region of deletion 2 (RD2) are susceptible to macrolides, whereas those which have retained RD2 (such as BCG-Japan, BCG-Russia, and BCG-Moreau) are resistant (4).
There is growing concern about the rising incidence of BCG-related complications associated with the human immunodeficiency virus/AIDS epidemic (7, 9) and the lack of evidence-based guidelines for the treatment of local and disseminated complications (13). Our study indicates that BCG vaccine strains differ in their susceptibilities to antituberculous drugs and suggests that these differences should be taken into account when selecting empirical treatment for BCG-related complications. This study also emphasizes the importance of genetic differences between BCG vaccine strains and highlights the need to document the particular BCG vaccine strains used in different countries (17). As different strains are sometimes used in the same country, recording the strain administered in an individual infant's immunization record would also be helpful.

ACKNOWLEDGMENTS
N.R. and M.T. are supported by fellowship awards from the European
Society of Pediatric Infectious Diseases and the University
of Melbourne. T.G.C. is supported by fellowship awards from
the Nossal Institute of Global Health and the University of
Melbourne.
We thank Gena Gonis and Lisa Markowski in the microbiology laboratories of the Royal Children's Hospital Melbourne for help in setting up the BCG cultures.
There are no conflicts of interest.

FOOTNOTES
* Corresponding author. Mailing address: Department of Paediatrics, The University of Melbourne, Royal Children's Hospital Melbourne, Flemington Road, Parkville, VIC 3052, Australia. Phone: 61 3 9345 4545. Fax: 61 3 9345 6667. E-mail:
nigel.curtis{at}rch.org.au 
Published ahead of print on 27 October 2008. 

REFERENCES
1 - Abe, C., I. Kobayashi, S. Mitarai, M. Wada, Y. Kawabe, T. Takashima, K. Suzuki, L. H. Sng, S. Wang, H. H. Htay, and H. Ogata. 2008. Biological and molecular characteristics of Mycobacterium tuberculosis clinical isolates with low-level resistance to isoniazid in Japan. J. Clin. Microbiol. 46:2263-2268.[Abstract/Free Full Text]
2 - Banerjee, A., E. Dubnau, A. Quemard, V. Balasubramanian, K. S. Um, T. Wilson, D. Collins, G. de Lisle, and W. R. Jacobs, Jr. 1994. inhA, a gene encoding a target for isoniazid and ethionamide in Mycobacterium tuberculosis. Science 263:227-230.[Abstract/Free Full Text]
3 - Behr, M. A., M. A. Wilson, W. P. Gill, H. Salamon, G. K. Schoolnik, S. Rane, and P. M. Small. 1999. Comparative genomics of BCG vaccines by whole-genome DNA microarray. Science 284:1520-1523.[Abstract/Free Full Text]
4 - Buriankova, K., F. Doucet-Populaire, O. Dorson, A. Gondran, J. C. Ghnassia, J. Weiser, and J. L. Pernodet. 2004. Molecular basis of intrinsic macrolide resistance in the Mycobacterium tuberculosis complex. Antimicrob. Agents Chemother. 48:143-150.[Abstract/Free Full Text]
5 - Durek, C., S. Rusch-Gerdes, D. Jocham, and A. Bohle. 2000. Sensitivity of BCG to modern antibiotics. Eur. Urol. 37(Suppl. 1):21-25.
6 - Goraya, J. S., and V. S. Virdi. 2001. Treatment of Calmette-Guerin bacillus adenitis: a metaanalysis. Pediatr. Infect. Dis. J. 20:632-634.[CrossRef][Medline]
7 - Hesseling, A. C., B. J. Marais, R. P. Gie, H. S. Schaaf, P. E. Fine, P. Godfrey-Faussett, and N. Beyers. 2007. The risk of disseminated Bacille Calmette-Guerin (BCG) disease in HIV-infected children. Vaccine 25:14-18.[CrossRef][Medline]
8 - Hesseling, A. C., H. Rabie, B. J. Marais, M. Manders, M. Lips, H. S. Schaaf, R. P. Gie, M. F. Cotton, P. D. van Helden, R. M. Warren, and N. Beyers. 2006. Bacille Calmette-Guerin vaccine-induced disease in HIV-infected and HIV-uninfected children. Clin. Infect. Dis. 42:548-558.[CrossRef][Medline]
9 - Hesseling, A. C., H. S. Schaaf, T. Victor, N. Beyers, B. J. Marais, M. F. Cotton, I. Wiid, R. P. Gie, P. van Helden, and R. M. Warren. 2004. Resistant Mycobacterium bovis bacillus Calmette-Guerin disease: implications for management of bacillus Calmette-Guerin disease in human immunodeficiency virus-infected children. Pediatr. Infect. Dis. J. 23:476-479.[Medline]
10 - Hok, T. T. 1964. A comparative study of the susceptibility to ethionamide, thiosemicarbazone, and isoniazid of tubercle bacilli from patients never treated with ethionamide or thiosemicarbazone. Am. Rev. Respir. Dis. 90:468-469.[Medline]
11 - Kruuner, A., M. D. Yates, and F. A. Drobniewski. 2006. Evaluation of MGIT 960-based antimicrobial testing and determination of critical concentrations of first- and second-line antimicrobial drugs with drug-resistant clinical strains of Mycobacterium tuberculosis. J. Clin. Microbiol. 44:811-818.[Abstract/Free Full Text]
12 - Lotte, A., O. Wasz-Hockert, N. Poisson, H. Engbaek, H. Landmann, U. Quast, B. Andrasofszky, L. Lugosi, I. Vadasz, P. Mihailescu, et al. 1988. Second IUATLD study on complications induced by intradermal BCG-vaccination. Bull. Int. Union Tuberc. Lung Dis. 63:47-59.[Medline]
13 - Mak, T. K., A. C. Hesseling, G. D. Hussey, and M. F. Cotton. 2008. Making BCG vaccination programmes safer in the HIV era. Lancet 372:786-787.[Medline]
14 - Rastogi, N., K. S. Goh, M. Berchel, and A. Bryskier. 2000. Activity of rifapentine and its metabolite 25-O-desacetylrifapentine compared with rifampicin and rifabutin against Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium bovis and M. bovis BCG. J. Antimicrob. Chemother. 46:565-570.[Abstract/Free Full Text]
15 - Rastogi, N., K. S. Goh, M. Berchel, and A. Bryskier. 2000. In vitro activities of the ketolides telithromycin (HMR 3647) and HMR 3004 compared to those of clarithromycin against slowly growing mycobacteria at pHs 6.8 and 7.4. Antimicrob. Agents Chemother. 44:2848-2852.[Abstract/Free Full Text]
16 - Rastogi, N., K. S. Goh, A. Bryskier, and A. Devallois. 1996. In vitro activities of levofloxacin used alone and in combination with first- and second-line antituberculous drugs against Mycobacterium tuberculosis. Antimicrob. Agents Chemother. 40:1610-1616.[Abstract]
17 - Ritz, N., W. A. Hanekom, R. Robins-Browne, W. J. Britton, and N. Curtis. 2008. Influence of BCG vaccine strain on the immune response and protection against tuberculosis. FEMS Microbiol. Rev. 32:821-841.[Medline]
18 - Rusch-Gerdes, S., G. E. Pfyffer, M. Casal, M. Chadwick, and S. Siddiqi. 2006. Multicenter laboratory validation of the BACTEC MGIT 960 technique for testing susceptibilities of Mycobacterium tuberculosis to classical second-line drugs and newer antimicrobials. J. Clin. Microbiol. 44:688-692.[Abstract/Free Full Text]
19 - Schaaf, H. S., D. P. Parkin, H. I. Seifart, C. J. Werely, P. B. Hesseling, P. D. van Helden, J. S. Maritz, and P. R. Donald. 2005. Isoniazid pharmacokinetics in children treated for respiratory tuberculosis. Arch. Dis. Child. 90:614-618.[Abstract/Free Full Text]
20 - Shishido, Y., S. Mitarai, K. Otomo, M. Seki, A. Sato, I. Yano, A. Koyama, and T. Hattori. 2007. Anti-tuberculosis drug susceptibility testing of Mycobacterium bovis BCG Tokyo strain. Int. J. Tuberc. Lung Dis. 11:1334-1338.[Medline]
21 - Turnbull, F. M., P. B. McIntyre, H. M. Achat, H. Wang, R. Stapledon, M. Gold, and M. A. Burgess. 2002. National study of adverse reactions after vaccination with bacille Calmette-Guerin. Clin. Infect. Dis. 34:447-453.[Medline]
22 - Wayne, L. G. 1974. Simple pyrazinamidase and urease tests for routine identification of mycobacteria. Am. Rev. Respir. Dis. 109:147-151.[Medline]
23 - World Health Organization. 2005. Isoniazid resistance of bacille Calmette-Guerin strains. Wkly. Epidemiol. Rec. 80:244.
Antimicrobial Agents and Chemotherapy, January 2009, p. 316-318, Vol. 53, No. 1
0066-4804/09/$08.00+0 doi:10.1128/AAC.01302-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.