Crohn's disease, a human disease similar to paratuberculosis in animals is the most painful and devastating disease that may involve infection with M. avium subsp. paratuberculosis (MAP), different genetic polymorphisms and an immune dysregulation syndrome. Treatment of Crohn's disease is most commonly based on 5-aminosalicylic acid (5-ASA) compounds, corticosteroids, and immunosuppressive agents. Recently, biological therapies using monoclonal antibodies against inflammatory cytokines have shown some positive results. However, all these therapies treat the symptoms not the cause of the disease

Ahmed, Niyaz

Cannas, Sara

Molicotti, Paola

Ortu, Silvia

Sechi, Leonardo Antonio

Zanetti, Stefania Anna Lucia

UnissResearch

BioMed Central
Annals of Clinical Microbiology and 
Antimicrobials
ssOpen AcceResearch
"In vitro" activities of antimycobacterial agents against 
Mycobacterium avium subsp. paratuberculosis linked to Crohn's 
Disease and Paratuberculosis
Stefania Zanetti1,2, Paola Molicotti1, Sara Cannas1, Silvia Ortu1, 
Niyaz Ahmed2,3 and Leonardo A Sechi*1,2
Address: 1Dipartimento di Scienze Biomediche, Sezione di Microbiologia Sperimentale e Clinica, Università degli studi di Sassari, Viale S. Pietro 
43/B, 07100 Sassari, Italy, 2ISOGEM Collaborative Network on Genetics of Mycobacteria (The International Society for Genomic and Evolutionary 
Microbiology, Sassari, Italy) and 3Pathogen Evolution Group, Center for DNA Fingerprinting and Diagnostics, Hyderabad, India
Email: Stefania Zanetti - sechila@gmail.com; Paola Molicotti - sardinia@hotmail.com; Sara Cannas - isogem@hotmail.com; 
Silvia Ortu - sardinia@hotmail.com; Niyaz Ahmed - niyaz.cdfd@gmail.com; Leonardo A Sechi* - sechila@uniss.it
* Corresponding author    
Background
Crohn's disease, a human disease similar to paratubercu-
losis in animals is the most painful and devastating dis-
ease that may involve infection with M. avium subsp.
paratuberculosis (MAP), different genetic polymorphisms
and an immune dysregulation syndrome [1-5]. Treatment
of Crohn's disease is most commonly based on 5-ami-
nosalicylic acid (5-ASA) compounds, corticosteroids, and
immunosuppressive agents. Recently, biological therapies
using monoclonal antibodies against inflammatory
cytokines have shown some positive results [6]. However,
all these therapies treat the symptoms not the cause of the
disease [6].
Antimycobacterial therapy against MAP has recently
showed promising results [7]. In fact, several authors pro-
vided convincing evidence that antimycobacterial com-
pounds may influence the course of the disease [4].
Currently, there are no antibiotics approved for the treat-
ment of Johne's disease or Crohn's disease. Considering
the worldwide magnitude and impact of health concerns
caused by MAP, we studied antimycobacterial activity of
different antituberculosis agents in vitro against MAP
bacilli of human and veterinary origins. Moreover, we
were interested to investigate the variability of susceptibil-
ity to antimycobacterial compounds of the MAP isolates
with respect to growth in agar medium and Congo red (a
planar hydrophobic molecule that binds to lipids and
lipoproteins, which are abundant in mycobacterial cell
walls) staining properties.
All the strains we used in this study were isolated from
humans and animals, the ATCC strain was a gift of Peter
Overduin, RIVM, Bilthoven, The Netherlands. Conven-
tional methods and a IS900 PCR test and sequencing of
the amplification products reconfirmed specific identity
of all the strains [1]. The strains (7 humans and 5 animals)
were tested against antimicrobial agents of several classes
(streptomycin, ciprofloxacin, ethambutol, dapsone,
rifampin, rifabutin and clarithromycin) which are com-
monly used for the treatment of mycobacterial diseases.
Bacteria were cultivated in Middlebrook7H9 medium
supplemented with Middlebrook ADC enrichment and
Mycobactin J following conventional methods [1,8].
MIGIT bottles were inoculated with 104 to 105 CFU/ml.
The antimycobacterial activity was determined by the
BACTEC MGIT 960 method with a modified protocol [8]
by adding mycobactin J and reading the mycobacterial
growth up to 90 days.
The concentration of the chemical agents tested were as
follows: streptomycin 0,5, 1, 2 and 4 μg/ml, ciprofloxacin
0,5, 1, 2, 4, 8 and 16 μg/ml, ethambutol 1, 2, 4, 8 and 16
μg/ml, rifampin 0.5, 1 and 2 μg/ml, rifabutin 0.5, 1, 2 μg/
ml, clarithromycin 2, 4, 8, 16 and 32 μg/ml and dapsone
Published: 15 November 2006
Annals of Clinical Microbiology and Antimicrobials 2006, 5:27 doi:10.1186/1476-0711-5-27
Received: 27 June 2006
Accepted: 15 November 2006
This article is available from: http://www.ann-clinmicrob.com/content/5/1/27
© 2006 Zanetti et al; licensee BioMed Central Ltd. 
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), 
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 3
(page number not for citation purposes)
Annals of Clinical Microbiology and Antimicrobials 2006, 5:27 http://www.ann-clinmicrob.com/content/5/1/278, 16 and 32 μg/ml. Experiments were repeated three
times. The MICs were interpreted by measuring the
change in the daily GI (DGI) for the drug-containing vials
compared with the GI for the control vials,
Activities of the antibiotics tested in this work correlated
well with those described in previous reports on suscepti-
bility of mycobacteria to antimicrobial agents except for
clarythromicin [8,9]. Strains were prepared for the agar
assay and plated in triplicate on 7H10 agar medium con-
taining 100 μg/ml of Congo Red (Sigma Chemical Co. St.
Louis, Mo, USA). Plates were incubated for 40–60 days to
observe colony morphology: rough or smooth, opaque or
transparent, red or white [11].
We observed that streptomycin, rifabutin and rifampin,
revealed a characteristic low MIC of 0,5 to 4 μg/ml, also
ciprofloxacin shoed a low MIC (range 0,5–16) whereas,
dapsone's MIC was very high at 32 μg/ml. MICs of two
other drugs were 2–16 μg/ml and 2–32 μg/ml for etham-
butol and clarithtromycin respectively. Susceptibility data
on human and animal isolates were carefully compared
and summarized in Table 1. Briefly, for streptomycin the
MIC range was of 0,5-2 μg/ml in both animal and human
strains, for ciprofloxacin it was at 0.5–16 μg/ml, inde-
pendently of the source of isolation, while rifampin pro-
duced a MIC of 0.5–1 μg/ml in human and bovine strains
and of >2 μg/ml for 2 bovine and 1 animal isolate. Rifab-
utin MIC was very similar to rifampin. Also ethambutol
generated a MIC of 2–8 μg/ml in human strains and 4–16
μg/ml in animal strains. The highest MIC values were
observed for dapsone: 32 μg/ml for human strains but 16
μg/ml for animal isolates. Clarithromycin showed a MIC
ranging from 2 to 32 μg/ml independently of the isolation
source, which is in contrast with previous reports [9-11]
where they report a lower MIC of 0.5–4 μg/ml, probably
due to differences in the pH medium used. Our results
concerning growth in Congo red medium agar showed
prevalently a rough transparent colony morphotype with
white coloration, whereas no smooth opaque colonies
with red coloration on Congo Red agar were detected as
previously observed except that for ATCC 43015 [11],
moreover, no correlation with antimicrobial susceptibili-
ties was observed.
A number of antimicrobial agents have been used to com-
bat flare ups in Crohn's Disease. These have included Cip-
rofloxacin and metronidazole, used either alone or in
combination. In recent studies, Crohn's patients were
treated with 3 antibiotics for a minimum of 24 months
[4,7].
MAP multiplies much more slowly than M. tuberculosis,
and so its treatment length should probably be double if
not triple of that of the later. Other mycobacterial dis-
eases, such as leprosy, also require prolonged treatment.
Infection of the lung due to Mycobacterium avium complex
and other mycobacteria, in patients who are not immuno-
compromised, has been treated for about 15 months to
five years [12]. Moreover, considering that clarithromycin
and ciprofloxacin are widely used antibiotics, strains
resistant to these drugs can be very common. Up to now,
there is a urgent need of new information on the activity
of available antibiotic regimens against MAP.
In conclusion, these results might represent a good start-
ing point to consider different drugs for treatment of the
disease forms where involvement of MAP is suspected, in
particular Crohn's disease in humans.
Table 1: In vitro activity of several drugs against MAP strains
Drugs (μg/ml)
Strains STR CPX EMB DPS RIF RIB CLA
ATCC 43015 0.5 0.5 2 16 0.5 2 2
182 human 2 4 4 32 0.5 1 4
516 human 2 8 4 16 1 1 16
517 human 2 4 8 32 >2 >2 16
090 human 2 8 8 16 1 1 16
186 human 1 4 2 32 1 1 4
064 human 1 2 4 32 0.5 1 4
387 cow 2 2 4 16 0.5 0.5 2
436 cow 2 4 8 16 >2 >2 16
088 cow 1 16 16 16 >2 >2 32
033 cow 2 4 16 16 0.5 0,5 16
518 cow 2 8 16 16 1 2 2
STR: Streptomycin, CPX: Ciprofloxacin, EMB: Ethambutol, DPS: Dapsone, RIF: Rifampin, RIB: Rifabutin, CLA: Clarithromycin. Source of 
isolation of strains is also indicated. Numbers represent the MIC value for each drug.Page 2 of 3
(page number not for citation purposes)
Annals of Clinical Microbiology and Antimicrobials 2006, 5:27 http://www.ann-clinmicrob.com/content/5/1/27Publish with BioMed Central   and  every 
scientist can read your work free of charge
"BioMed Central will be the most significant development for 
disseminating the results of biomedical research in our lifetime."
Sir Paul Nurse, Cancer Research UK
Your research papers will be:
available free of charge to the entire biomedical community
peer reviewed and published immediately upon acceptance
cited in PubMed and archived on PubMed Central 
yours — you keep the copyright
Submit your manuscript here:
http://www.biomedcentral.com/info/publishing_adv.asp
BioMedcentral
Acknowledgements
This work was supported by the PRIN Italian 2005, contract n. 
2005064503_03.
References
1. Sechi LA, Scanu AM, Molicotti P, Cannas S, Mura M, Dettori G, Fadda
G, Zanetti S: Detection and isolation of Mycobacterium avium
subspecies paratuberculosis from intestinal mucosal biopsies
of patients with and without Crohn's disease in Sardinia.  Am
J Gastroenterol 2005, 100:1537-1538.
2. Bull TJ, McMinn EJ, Sidi-Boumedine K, Skull A, Durkin D, Neild P,
Rhodes G, Pickup R, Hermon Taylor J: Detection and verification
of Mycobacterium avium subsp. paratuberculosis in fresh ileo-
colonic mucosal biopsy specimens from individuals with and
without Crohn's disease.  J Clin Microbiol 2003, 41:2915-2923.
3. Naser SA, Ghobrial G, Romero C, Valentine JF: Culture of Myco-
bacterium avium subspecies paratuberculosis from the blood
of patients with Crohn's disease.  Lancet 2004, 364:1039-1044.
4. Hermon-Taylor J: Treatment with drugs active against Myco-
bacterium avium subspecies paratuberculosis can heal Crohn's
disease: more evidence for a neglected public health trag-
edy.  Dig Liver Dis 2002, 34:9-12.
5. Greenstein RJ, Collins MT: Emerging pathogens: is Mycobacte-
rium avium subspecies paratuberculosis zoonotic?  Lancet 2004,
364:396-397.
6. Blonski W, Lichtenstein GR: Complications of biological therapy
for inflammatory bowel diseases.  Curr Opin Gastroenterol 2006,
22:30-43.
7. Borody TJ, Leis S, Warren EF, Surace R: Treatment of severe
Crohn's disease using antimycobacterial triple therapy-
approaching a cure?  Dig Liver Dis 2002, 34:29-38.
8. Ardito F, Posteraro B, Sanguinetti M, Zanetti S, Fadda G: Evaluation
of BACTEC Mycobacteria Growth Indicator Tube (MGIT
960) automated system for drug susceptibility testing of
Mycobacterium tuberculosis.  J Clin Microbiol 2001, 39:4440-4444.
9. Rastogi N, Goh KS, Labrousse V: Activity of clarithromycin com-
pared with those of other drugs against Mycobacterium
paratuberculosis and further enhancement of its extracellular
and intracellular activities by ethambutol.  Antimicrob Agents
Chemother 1992, 36:2843-2846.
10. Rastogi N, Goh KS, Berchel M, Bryskier A: In vitro activities of the
ketolides telithromycin (HMR 3647) and HMR 3004 com-
pared to those of clarithromycin against slowly growing
mycobacteria at pHs 6.8 and 7.4.  Antimicrob Agents Chemother
2000, 44:2848-2852.
11. Parrish NM, Ko CG, Dick JD, Jones PBm, Ellingson JL: Growth,
Congo Red agar colony morphotypes and antibiotic suscep-
tibility testing of Mycobacterium avium subspecies paratuber-
culosis.  Clin Med Res 2004, 2:107-114.
12. Koh WJ, Kwon OJ, Lee KS: Diagnosis and treatment of nontu-
berculous mycobacterial pulmonary diseases: a Korean per-
spective.  J Korean Med Sci 2005, 20:913-925.Page 3 of 3
(page number not for citation purposes)


"In vitro" activities of antimycobacterial agents against

<i>Mycobacterium avium</i> subsp. <i>paratuberculosis</i> linked to Crohn's

disease and paratuberculosis

"In vitro" activities of antimycobacterial agents against <i>Mycobacterium avium</i> subsp. <i>paratuberculosis</i> linked to Crohn's disease and paratuberculosis

Abstract

Similar works

Full text

Available Versions

UnissResearch