Antibiotic Therapy for Active Crohn's Disease Targeting Pathogens: An Overview and Update

Crohn's disease (CD) is a multifactorial chronic disorder that involves a combination of factors, including genetics, immune response, and gut microbiota. Therapy includes salicylates, immunosuppressive agents, corticosteroids, and biologic drugs. International guidelines do not recommend the use of antibiotics for CD patients, except in the case of septic complications. Increasing evidence of the involvement of gut bacteria in this chronic disease supports the rationale for using antibiotics as the primary treatment for active CD. In recent decades, several pathogens have been reported to be involved in the development of CD, but only Escherichia coli (E. coli) and Mycobacterium avium paratubercolosis (MAP) have aroused interest due to their strong association with CD pathogenesis. Several meta-analyses have been published concerning antibiotic treatment for CD patients, but randomized trials testing antibiotic treatment against E. coli and MAP have not shown prolonged benefits and have generated conflicting results; several questions are still unresolved regarding trial design, antibiotic dosing, the formulation used, the treatment course, and the outcome measures. In this paper, we provide an overview and update of the trials testing antibiotic treatment for active CD patients, taking into account the role of pathogens, the mechanisms by which different antibiotics act on harmful pathogens, and antibiotic resistance. Finally, we also present new lines of study for the future regarding the use of antibiotics to treat patients with active CD.

First Report on Ovine Paratuberculosis in the Sudan: Diagnosis Using Different Techniques

Paratuberculosis (PTB) has been reported in the Sudan in cattle and goats for more than 50 years but has never been reported in sheep. However, suspicion of the disease in a breeding flock of sheep in Khartoum North locality was made due to a history of unknown cause of loss of weight. Blood and faecal samples were collected from all animals (N = 59): harvested sera were tested for anti-Mycobacterium avium subsp. paratuberculosis (MAP) antibodies by Enzyme Linked Immunosorbent Assay (ELISA); faeces were screened for acid-fast bacilli by Ziehl-Neelsen staining, tested for MAP DNA by recombinase polymerase amplification (RPA) and some faecal samples were cultured for MAP isolation. Typical MAP acid-fast bacilli were seen in 10.2% (6/59) of the faecal smears, 37.5% of the tested faecal samples (12/32) were positive for MAP DNA and only 3 (5.1%) animals were seropositive for MAP. MAP positive cultures were obtained from 2 out the 6 samples showing typical MAP acid-fast bacilli; the isolates were confirmed by real-time PCR and sequencing. As sheep are animals of utmost economic importance as the main export animals for the country, this first report of ovine PTB warrants special considerations and more investigations for planning control programmes of the disease.

Use of uncoated magnetic beads to capture Mycobacterium smegmatis and Mycobacterium avium paratuberculosis prior detection by mycobacteriophage D29 and real-time-PCR

Uncoated tosyl-activated magnetic beads were evaluated to capture Mycobacterium smegmatis and Mycobacterium avium subspecies paratuberculosis (MAP) from spiked feces, milk, and urine. Centrifugation and uncoated magnetic beads recovered more than 99% and 93%, respectively, of 1.68 × 10⁷ CFU/mL, 1.68 × 10⁶ CFU/mL and 1.68 × 10⁵ CFU/mL M. smegmatis cells resuspended in phosphate buffer saline. The use of magnetic beads was more efficient to concentrate cells from 1.68 × 10⁴ CFU/mL of M. smegmatis than centrifugation. Likewise, the F57-qPCR detection of MAP cells was different whether they were recovered by beads or centrifugation; cycle threshold (Ct) was lower (p < 0.05) for the detection of MAP cells recovered by beads than centrifugation, indicative of greater recovery. Magnetic separation of MAP cells from milk, urine, and feces specimens was demonstrated by detection of F57 and IS900 sequences. Beads captured no less than 10⁹ CFU/mL from feces and no less than 10⁴ CFU/mL from milk and urine suspensions. In another detection strategy, M. smegmatis coupled to magnetic beads were infected by mycobacteriophage D29. Plaque forming units were observed after 24 h of incubation from urine samples containing 2 × 10⁵ and 2 × 10³ CFU/mL M. smegmatis. The results of this study provide a promising tool for diagnosis of tuberculosis and Johne's disease.

Putting Crohn's on the MAP: Five Common Questions on the Contribution of Mycobacterium avium subspecies paratuberculosis to the Pathophysiology of Crohn's Disease

For decades, Mycobacterium avium subspecies paratuberculosis (MAP) has been linked to the pathogenesis of Crohn's disease. Despite many investigations and research efforts, there remains no clear unifying explanation of its pathogenicity to humans. Proponents argue Crohn's disease shares many identical features with a granulomatous infection in ruminants termed Johne's disease and similarities with ileo-cecal tuberculosis. Both are caused by species within the Mycobacterium genus. Sceptics assert that since MAP is found in individuals diagnosed with Crohn's disease as well as in healthy population controls, any association with CD is coincidental. This view is supported by the uncertain response of patients to antimicrobial therapy. This report aims to address the controversial aspects of this proposition with information and knowledge gathered from several disciplines, including microbiology and veterinary medicine. The authors hope that this discussion will stimulate further research aimed at confirming or refuting the contribution of MAP to the pathogenesis of Crohn's disease and ultimately lead to advanced targeted clinical therapies.

paratuberculosis in Dairy Cattle in Khartoum State, Sudan

Paratuberculosis, caused by Mycobacterium avium subspecies paratuberculosis (MAP), is a chronic wasting disease mainly of domestic and wild ruminants. It occurs worldwide, causing significant economic losses through decreased productivity, low fertility, increased cull rates and mortality. It is listed by the OIE (World Organization for Animal Health) as a disease of concern to trade in animals. Prevalence of this disease can be studied by detecting anti-MAP antibodies by Enzyme linked immunosorbent Assay (ELISA). The aim of this study was to investigate the current prevalence of MAP infection in cattle in Khartoum State. The overall apparent prevalence of MAP infection was found to be 6.3% and 18.9% at animal and herd levels, respectively. All seropositive animals were cross-bred females of good body condition; most of them (>90%) were >3 years old and >50% were from medium-sized herds in Omdurman. No significant association (p > 0.05) was found between seropositivity and animal herd size. The prevalence of MAP infection in Khartoum State is still low to medium compared to other parts of the world, but it is comparable to those reported from other African countries. Further studies with the view of designing nationwide surveys in domestic ruminants and camels in other states of the country are needed for establishing control programmes.

Anti-Mycobacterial Antibiotic Therapy Induces Remission in Active Paediatric Crohn's Disease. Microorganisms. 2020;8:1112. [PMID: 32722117 PMCID: PMC7464505 DOI: 10.3390/microorganisms8081112]

Crohn’s disease is increasing in incidence and prevalence in younger people and is of a particularly aggressive nature. One emerging treatment targets Mycobacterium avium paratuberculosis (MAP), an organism implicated in the causation of Crohn’s disease. This study reviewed a cohort of paediatric patients with active Crohn’s disease treated with Anti-Mycobacterial Antibiotic Therapy (AMAT). Sixteen paediatric patients, the majority of whom had failed conventional immunosuppressive therapy, were treated with AMAT. Endoscopic remission was scored using the Simple Endoscopic Score for Crohn’s Disease and clinical remission was assessed using the Weighted Paediatric Crohn’s Disease Activity Index (wPCDAI). Inflammatory blood markers were also routinely recorded. Patients were followed up clinically and endoscopically during treatment after an average of two months (range 1–6) and 17 months (range 2–49), respectively. A significant reduction in both scores assessing clinical improvement (p < 0.001) and mucosal healing (p < 0.0078) was observed at these timepoints; 47% of patients had achieved clinical remission and 63% endoscopic remission. Haemoglobin and serum inflammatory markers normalised for more than 50% of the cohort by six months of treatment. No adverse effects were reported throughout treatment. This is the first report of Anti-Mycobacterial Antibiotic Therapy offering a safe and efficacious therapy for paediatric patients with Crohn’s disease. Further larger randomised studies are required in order to validate these findings.

Mycobacterium tuberculosis extracellular vesicle-associated lipoprotein LpqH as a potential biomarker to distinguish paratuberculosis infection or vaccination from tuberculosis infection

BACKGROUND

Both bovine tuberculosis (TB) and paratuberculosis (PTB) are serious and widespread bacterial infections affecting many domestic and wild animal species. However, current vaccines do not confer complete protection and cause interference with other diagnostics tests, including bovine TB. Therefore, the development of "Differentiating Infected from Vaccinated Animals" (DIVA) tests are a pressing need. In this study, we have tested the feasibility of mycobacterial extracellular vesicles (EVs) as potential source of biomarkers to discriminate between Mycobacterium bovis infected, Mycobacterium avium subsp. paratuberculosis (MAP) infected and MAP-vaccinated cows. We have, initially, characterized vesicle production in the two most medically relevant species of mycobacteria for livestock, MAP and M. bovis, for being responsible for tuberculosis (TB) and paratuberculosis (PTB).

RESULTS

Our results indicate that these two species produce EVs with different kinetics, morphology and size distribution. Analysis of the immunogenicity of both type of EVs showed some cross reactivity with sera from PTB+ and TB+ cows, suggesting a limited diagnostic capacity for both EVs. Conversely, we noticed that Mycobacterium tuberculosis (Mtb) EVs showed some differential reactivity between sera from MAP-vaccinated or PTB+ cows from TB+ ones. Mass spectrometry analysis (MS) identified a 19-kDa EV-associated lipoprotein as the main source of the differential reactivity.

CONCLUSIONS

LpqH could be a good plasma biomarker with capacity to distinguish PTB+ or MAP-vaccinated cows from cows infected with TB.

Characterization and Differentiation of Mycobacterium avium subsp. paratuberculosis from Other Mycobacteria Using Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne's disease in cattle, is responsible for significant economic losses to the US dairy industry. The pathogen has also been associated with chronic human diseases like Crohn's disease, type 1 diabetes and multiple sclerosis. Determining causation requires rapid characterization and source tracking the pathogen. Here, we used matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to characterize and differentiate strains of MAP from 14 other species of Mycobacterium from bovine, human, and environmental sources. Lysates from cells disrupted by bead beating in TFA-acetonitrile solution were analyzed by MALDI-TOF. MAP strains were differentiated by mass spectral profiles that are distinct from each other and from other Mycobacterium species. Cluster analysis of spectral profiles indicates two distinct clusters, one dominated by the members of avium complex and a second group dominated by members of fortuitum and parafortuitum complexes. We believe that MALDI-TOF methods can be used to differentiate and source-track MAP strains.

Is Mycobacterium avium paratuberculosis the Trigger in the Crohn's Disease Spectrum?

We present and discuss a 30-month investigation of a patient that presented with abdominal pain, postprandial diarrhea, bloating, and night sweats and was treated for Crohn’s disease without significant improvement. The patient underwent an ileocecetomy with removal of an atonic segment with resolution of functional gastrointestinal symptoms, but profound night sweats continued postoperatively. The patient was presumptively treated for a mixed mycobacterial infection, blood cultures later grew Mycobacterium avium paratuberculosis (MAP), and she improved over time. We discuss MAP and its possible relationship to Crohn’s disease.

Concurrent Resolution of Chronic Diarrhea Likely Due to Crohn's Disease and Infection with Mycobacterium avium paratuberculosis

Examination of samples of stool from a 61-year-old male patient, presenting with the clinical symptoms of Crohn's disease (CD), revealed massive shedding of acid fast bacilli with the morphology of Mycobacterium avium paratuberculosis (MAP), the causative agent of Johne's disease in cattle. MAP was cultured from the stool. Biotyping of the bacterium isolated from cultures of stool demonstrated, it was the Indian Bison biotype of MAP, the dominant biotype infecting livestock and humans in India. Based on this finding and because the patient was unresponsive to standard therapy used in India to treat patients with gastrointestinal inflammatory disorders, the patient was placed on a regimen of multi-antibiotic therapy, currently used to treat tuberculosis and CD. After 1 year of treatment, the patient's health was restored, concurrent with cessation of shedding of MAP in his stool. This patient is the first case shown to shed MAP from the stool who was cured of infection with antibiotics and who was concurrently cured of clinical signs of CD.

Species-specific engagement of human nucleotide oligomerization domain 2 (NOD)2 and Toll-like receptor (TLR) signalling upon intracellular bacterial infection: role of Crohn's associated NOD2 gene variants

Recognition of bacterial peptidoglycan-derived muramyl-dipeptide (MDP) by nucleotide oligomerization domain 2 (NOD2) induces crucial innate immune responses. Most bacteria carry the N-acetylated form of MDP (A-MDP) in their cell membranes, whereas N-glycolyl MDP (G-MDP) is typical for mycobacteria. Experimental murine studies have reported G-MDP to have a greater NOD2-stimulating capacity than A-MDP. As NOD2 polymorphisms are associated with Crohn's disease (CD), a link has been suggested between mycobacterial infections and CD. Thus, the aim was to investigate if NOD2 responses are dependent upon type of MDP and further to determine the role of NOD2 gene variants for the bacterial recognition in CD. The response pattern to A-MDP, G-MDP, Mycobacterium segmatis (expressing mainly G-MDP) and M. segmatisΔnamH (expressing A-MDP), Listeria monocytogenes (LM) (an A-MDP-containing bacteria) and M. avium paratuberculosis (MAP) (a G-MDP-containing bacteria associated with CD) was investigated in human peripheral blood mononuclear cells (PBMCs). A-MDP and M. segmatisΔnamH induced significantly higher tumour necrosis factor (TNF)-α protein levels in healthy wild-type NOD2 PBMCs compared with G-MDP and M. segmatis. NOD2 mutations resulted in a low tumour necrosis factor (TNF)-α protein secretion following stimulation with LM. Contrary to this, TNF-α levels were unchanged upon MAP stimulation regardless of NOD2 genotype and MAP solely activated NOD2- and Toll-like receptor (TLRs)-pathway with an enhanced production of interleukin (IL)-1β and IL-10. In conclusion, the results indicate that CD-associated NOD2 deficiencies might affect the response towards a broader array of commensal and pathogenic bacteria expressing A-MDP, whereas they attenuate the role of mycobacteria in the pathogenesis of CD.

Mycobacterium avium paratuberculosis infection augments innate immune responses following intestinal epithelial injury

We wanted to determine if augmented innate immune activation is associated with lesion development in a mycobacterial enhanced intestinal injury model. We evaluated the local immune response in a Mycobacterium avium paratuberculosis + dextran sulfate sodium (Map + DSS) model using BALB/c and severe combined immunodeficient (SCID) mice. Map + DSS BALB/c and SCID mice displayed a similar disease phenotype. Moreover, Map + DSS SCID mice had increased expression of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), inducible nitric oxide synthase (iNOS) and increased numbers of F4/80 positive cells. Additionally, Map antigen is co-localized with iNOS and IL-1β positive cells. This suggests that subclinical Map infection promotes innate immune activation following injury to the intestinal epithelium.

Lack of evidence of paratuberculosis in wild canids from Southwestern Europe

Wild carnivores are at the top of the trophic chain. They are predators and carrion consumers, and thus, prone to come in contact with disease agents contaminating the environment or infecting live or dead animals. We hypothesized that wild canids could be used as sentinels for the detection of regions with higher Mycobacterium avium paratuberculosis (MAP) prevalence in wild and domestic animals. To test this hypothesis, we set up an ELISA to test 262 wolf (Canis lupus) and fox (Vulpes vulpes) sera for MAP-specific antibodies and processed a subset of samples for culture (n = 61), MAP-specific PCR (15) and histopathology (14). In wolves, the optical density (OD) values in the ELISA were continuously distributed. Ten fox sera (4%) had OD readings of over twice the mean, suggesting contact with mycobacteria. However, all samples tested by PCR were negative for both IS900 and ISMAP02 sequences, and samples cultured for MAP yielded no growth. No visible paratuberculosis or tuberculosis-compatible lesions were recorded. On histopathological examination, no lesions compatible with mycobacterial diseases were observed. These results suggest that wild canids show little or no evidence of paratuberculosis and are unlikely to be useful sentinels for the detection of MAP in Southwestern Europe.