Actinobacillus pleuropneumoniae is a gram negative bacterium, mainly responsible for swine pleuropneumonia. Although it was isolated for the first time in 1957, it was not until many decades later (1983) that it was placed in the genus Actinobacillus, since DNA tests showed certain similarities with bacteria of the same genus.
It is a bacterium that has wreaked havoc on pig farms, causing an infection that can be life threatening, as well as being highly contagious and difficult to eradicate.
Pig farms are the perfect place for Actinobacillus pleuropneumoniae to grow. Source: Pixabay
Taxonomy
The taxonomic classification of Actinobacillus pleuropneumoniae is as follows:
- Domain: Bacteria
- Kingdom: Monera
- Phylum: Proteobacteria
- Class: Gammaproteobacteria
- Order: Pasteurellales
- Genus: Actinobacillus
- Species: Actinobacillus pleuropneumoniae
characteristics
Actinobacillus pleuropneumoniae is a gram negative bacterium. When subjected to the gram stain procedure, instead of turning purple, they are colored fuchsia. This occurs because its cell wall does not have the required structure to retain the dye particles.
For its culture, 5% blood agar is used and conditions that cover a temperature of 35 ° C - 37 ° C are needed. The time it takes for colonies to develop is 48-72 hours. In the cultures, a small hemolytic halo is observed around the colonies. Therefore Actinobacillus pleuropneumoniae is a beta hemolytic bacterium.
When it is desired to differentially identify this bacterium, it is subjected to numerous biochemical tests, in which the following results are obtained:
- Positive urease: which means that it is capable of hydrolyzing the urea molecule to obtain ammonium and carbon dioxide as products. This is thanks to the synthesis of the enzyme urease that catalyzes this reaction.
- Negative Indole : This bacteria cannot break down tryptophan (amino acid) to obtain indole. This is because Actinobacillus pleuropneumoniae does not synthesize any of the enzymes of the tryptophanase complex.
- Reduces nitrates to nitrites: this bacterium synthesizes the enzyme nitrate reductase, which allows it to reduce nitrates to nitrites, obtaining water as a secondary product in the process.
Likewise, this bacterium is considered a facultative anaerobic organism, that is, it can develop both in the presence and in the absence of oxygen. Actinobacillus pleuropneumoniae also carries out the fermentation process of some carbohydrates such as ribose and glucose to obtain organic compounds.
The latter, on occasions, has been a determining element when making a differential diagnosis of this bacterium.
Morphology
In the case of symptomatic patients, they manifest the following signs and symptoms:
- Temperature rise
- Lethargy and apathy
- Apathy
- Obvious dyspnea
- Cough without expectoration
- Bloody, frothy discharge from both the mouth and nose (this is rare)
In this sense, if the infection is not treated in time, a chronic form develops that is characterized by a persistent cough and growth retardation.
Likewise, in the lung tissue there are certain lesions, which are characterized by being dark red and firm, like infarcted areas. It can be unilateral or bilateral, together with fibrinous pleurisy.
Treatment
The treatment for this pathology focuses on the eradication of the bacteria through the use of antibiotics. The most used are:
- Doxycycline
- Oxytetracycline
- Penicillin
- Ampicillin
- Amoxicillin
- Valnemulin
- Tulathromycin
Taking into account that several strains of this bacterium have developed resistance to some antibiotics such as tetracyclines, it is important to perform a sensitivity test for the treatment to be really effective.
References
- Actinobacillus pleuropneumoniae, obtained from: ivami.com.
- Gutiérrez, C., Cabrero, R., Rodríguez, J. and Rodríguez, E. (1997). Actinobacillus pleuropneumoniae in "Actinobacillus pleuropneumoniae and porcine pleuropneumonia". Editorial Porci.
- Gutiérrez, C., Rodríguez, E. and De la Puente, V. (2001). Actinobacillus pleuropneumoniae and porcine pleuropneumonia in "Porcine respiratory complex: a compendium of research". Schering-Plow Animal Health.
- López, J. and Jiménez, M. Porcine plauropneumonia due to Actinobacillus pleuropneumoniae. Vaccine prophylaxis. Anaporc
- Mori, L., Calle, S., Pinto, C., Torres, M., Falcón, N. and Morales, S. (2010). Frequency of infection with Actinobacillus pleuropneumoniae in modernized pig farms of the Peruvian coast. Journal of Veterinary Research of Peru. 21 (1).
- To, H., Teshima, K., Nagai, S., Zielinski, G., Koyama, T., Lee, J., Bessone, F., Nagano, T., Oshima, A. and Tsutsumi, N. (2017). Characterization of Actinobacillus pleuropneumoniae field strains antigenically related to the 3-6-8-15 group from diseased pigs in Japan and Argentina. Argentine Journal of Microbiology. 50 (1) 1-112.