MYCOBACTERIUM AND ENVIRONMENT

Mycobacteriaare known for their enhanced survival ability under adverse environmental conditions (dust and dried respiratory secretions). However, it is not clear what the exact mechanism that protects these pathogens in external environment of human and animal bodies is. It should be mentioned that there is a large group of Mycabacteria comprising saprophytic species (atypical/ non-tuberculous mycobacteria) that are mainly non-pathogenic or only occasionally pathogenic. There are many reports on the isolation of environmental Mycobacteria from soil, bogs, surface water, ground water and sea water as natural habitats (Norby et al., 2007; Tsintzou et al., 2000; LeChevallier et al., 2000; Young et al., 2005).

Figure 2.15.1. Mycobacteriaspp. transmission from animals to humans Environmental Aspects of Zoonotic Diseases 98

(including their excretions such as sputum, urine, milk and feces), consumption of uncooked milk or meat from tuberculous animals and inhalation of droplets when in contact with ill persons or animals (O’Reilly and Daborn, 1995). Historically, based on genetic evidence, the common ancestor of the causative agents of tuberculosis emerged 40,000 years in East Africa, an area from which the modern human population disseminated around the world, too. Between 10,000 and to 20,000 years later the pathogen split into two major lineages: one which infects humanoids and a second which spread from human to animals. In recent times (∼180 years ago), with overlapping human population expansion and industrial revolution, the human-associated pathogen lineages expanded (Wirthet al., 2008). Some authors also indicated an additional direction that may impact these pathogens’ persistence besides demographic expansion, especially in crowded cities (e.g., bacterial dormancy) (Shleeva et al., 2010). The dormancy state of bacterial pathogens expresses itself by a drastic decrease of metabolic activity, enhanced resistance to harmful factors, and absence of cell division, all increasing its survival potential under unfavorable environmental conditions (Archuletaet al., 2005). Severalin vitromodels, including prolonged hypoxic incubation in the post-stationary phase or under microaerophilic conditions after rifampicin treatment, demonstrated that viable cells ofM. tuberculosisare capable of transition to a“non-culturable”state and that their colony forming capacity may be restored by special procedures (Sun and Zhang, 1999; Hu et al., 2000). Whether these reports are correct or biased, the persistence of non-spore forming M.

tuberculosiscomplex in less populated areas requires further research efforts.

Finally, one should ask oneself whether this pathogen is present in the blood of infected animals there is any possible transfection through blood feeding insects such as mosquitoes, ticks, etc. Allen (1987) showed that fecal pellets (kept at room temperature) of an oriental cockroach that ingested heat-fixed sputum smears of viableM. tuberculosisintended for microscopic examination were positive for viable bacteria for up to 8 weeks. Fischer et al. (2003) infected experimentally nymphs of the same oriental cockroach (Blatta orientalis) with M. avium ssp.paratuberculosis and the avian tuberculosis M. avium ssp. avium. Both subspecies were isolated in excreta after 3 days and in homogenized bodies after 10 days. The authors Figure 2.15.2. Suggested potential transmission routes ofM. ulceransshared by environment, possums, mosquitoes and humans

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indicated a possible viable avian pathogen shedding and transmission, while infected orally. Kovalev (1983) discussed the role of ectoparasites (ticks) and wild birds as circulators, distributors and natural foci ofM.

avium tuberculosis. Furthermore, an aquatic insect predator (Naucoris cimicoides, of the order Hemiptera, genus Nepidae, commonly called waterscorpion) was shown to be infected by M. ulcerans through coelomic plasmatocytes that act as shuttle cells that deliverM. ulceransto the salivary glands of these insects (Marsollieret al., 2005). This is not a science fiction scenario as our cities surroundings are populated by many insects that have direct contact with humans and animals.

An interesting explanation ofM. ulceranstransmission and reservoirs in Australian mammals such as possums (Fyfeet al., 2010) was recently published. The authors through intensive study of fecal content of animals in endemic areas for M. ulcerans, found 41% positive samples compared to,1% in non-endemic areas. These findings indicate terrestrial mammals as additional reservoirs of M. ulcerans (Figure 2.15.2).

2.15.2 REFERENCES

Allen, B.W. (1987) Excretion of viable tubercle bacilli by Blatta orientalis (the oriental cockroach) following ingestion of heat-fixed sputum smears: a laboratory investigation.Trans. R. Soc. Trop. Med. Hyg.81, 98–99.

Archuleta, R.J., Hoppes, P.Y. & Primm, T.P. (2005) Mycobacterium avium enters a state of metabolic dormancy in response to starvation.Tuber85, 147–158.

Aronson, J. D. (1926). Spontaneous tuberculosis in salt water fish.J. Infect. Dis.39, 314–320.

Chiodini, R.J. & Rossiter, C.A. (1996) Paratuberculosis: a potential zoonosis ?Vet. Clin. N. Am. Food Anim. Pract.12, 457–467.

Fischer, O.A., Matlova, L. Dvorska, L., Svastova, P. & Pavlik, I. (2003) Nymphs of the Oriental cockroach (Blatta orientalis) as passive vectors of causal agents of avian tuberculosis and paratuberculosis.Med. Vet. Entomol.17, 145–150.

Fyfe, J.A.M., Lavender, C.J., Handasyde, K.A., Legione. A.R., O’Brien. C.R.et al.(2010) A major role for mammals in the ecology of Mycobacterium ulcerans.PLoS Negl Trop Dis4(8): e791. doi:10.1371/journal.pntd.0000791.

Gray, S.F., Smith, R.S., Reynolds, N.J. & Williams, E.W. (1990) Fish tank granuloma.Br. Med. J.300, 1069–1070.

Hu, Y.M., Mangan, J.A., Dhillon, J., Sole, K.M., Mitchison, D.A.et al.(2000) Detection of mRNA transcripts and active transcription in persistentMycobacterium tuberculosisinduced by exposure to rifampin or pyrazinamide.

J. Bacteriol.182, 6358–6365.

Kovalev, G.K. (1983) The role of wild birds and their ectoparasites (ticks) in the circulation and distribution of M. avium and possible formation of natural foci of avian tuberculosis.J Hyg Epidemiol Microbiol Immunol27, 281–288.

LeChevallier, M.W., Norton, C.D., Falkinham, J.O.-III, Williams, M.D. & Taylor, R.H. (2000) Mycobacterium avium complex in drinking water.Proceedings - Annual Conference, American Water Works Association, 777–788.

Marsollier, L., Aubry, J., Coutanceau, E., Saint Andre, J-P., Small, P.L.et al.(2005) Colonization of the salivary glands of Naucoris cimicoides by Mycobacterium ulcerans requires host plasmatocytes and a macrolide toxin, mycolactone.Cell. Microbiol.7, 935–943.

Mycobacteria in drinking water distribution systems: ecology and significance for human health.FEMS Microbiol. Rev.

29, 911–934.

Norby, B., Fosgate, G.T., Manning, E.J.B., Collins, M.T. & Roussel, A.J. (2007) Environmental mycobacteria in soil and water on beef ranches: association between presence of cultivable mycobacteria and soil and water physicochemical characteristics.Vet. Microbiol.124, 153–159.

O’Reilly, L.M. & Daborn, C.J. (1995) The epidemiology ofMycobacyterium bovisinfections in animals and man: a review.Tuber. Lung Dis.76, 1–46.

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Sun, Z. & Zhang, Y., (1999) Spent culture supernatant ofMycobacterium tuberculosisH37Ra improves viability of aged cultures of this strain and allows small inocula to initiate growth.J. Bacteriol.181, 7626–7628.

Tsintzou, A., Vantarakis, A., Pagonopoulou, O., Athanassiadou, A. & Papapetropoulou, M. (2000) Environmental mycobacteria in drinking water before and after replacement of the water distribution network.Water, Air, and Soil Pollution120, 273–282.

Uganda Buruli Group (1971) Epidemiology ofMycobacterium ulceransinfection (Buruli ulcer) at Kinyara, Uganda.

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Vaerewijck, M.J.M., Huys, G., Palomino, J.C., Swings, J. & Portaels, F. (2005) Mycobacteria in drinking water distribution systems: ecology and significance for human health.FEMS Microbiol. Rev.29, 911–934.

Wirth, T., Hildebrand, F., Allix-Béguec, C., Wölbeling, F., Kubica, T.et al.(2008) Origin, spread and demography of theMycobacterium tuberculosiscomplex.PLoS Pathog4(9): e1000160. doi:10.1371/journal.ppat.1000160.

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Chapter 2.16 Pasteurelloses

[PASTEURELLA MULTOCIDA]

Pasteurella multocidais a non-motile gram-negative cocobacillus (pleomorphic) facultative anaerobe that forms capsules.Pasteurella multocidastrains based on capsule antigens are divided into 5 serogroups (A, B, D, E and F) and later classified into 16 serotypes (1–16) based primarily on lipopolysaccharide antigens (Carter, 1955; Heddlestonet al., 1972). Other closely related species are:P. dagmatis, P. canis, P. caballi, P. stomatis, andP. haemolytica. Pasteurellacan be found in wild and domestic animals (including pets and zoo animals) and even more exotic ones such as tortoises (Kochet al., 1996; Snipeset al., 1980).

Transmission from animals to humans is mainly through scratches or bites from carrier pets and other animals with which they come in contact (Garcia, 1997). The disease manifests itself as skin/subcutaneous septic phlegmon, edema, pain, fever, vomiting, headache, diarrhea, lymphangitis and rarely sepsis, pneumonia, meningitis and endocarditis.