Mycoplasma mycoides is a bacterial pathogen that primarily affects livestock, particularly cattle. This microorganism belongs to the genus Mycoplasma within the class Mollicutes. It is a significant concern in animal health globally, impacting agricultural economies. This bacterium possesses distinct features, such as its exceptionally small size and the absence of a cell wall, which influence its survival and interaction with host organisms.
Unique Characteristics of Mycoplasma mycoides
Mycoplasma mycoides is classified within the Mollicutes, a group of bacteria known for their diminutive size and simple structure. Unlike most other bacteria, it completely lacks a rigid cell wall, making it resistant to many common antibiotics that target cell wall synthesis. This allows it to adopt various shapes, described as pleomorphic, and evade certain host immune responses.
The bacterium has a remarkably small genome, producing a limited number of proteins compared to other bacteria. This minimal genetic content makes Mycoplasma mycoides highly dependent on its host for many metabolic functions and nutrients. It can also form biofilms under stressful conditions, offering protection from the environment, host defenses, and antibiotics, potentially increasing its virulence.
Contagious Bovine Pleuropneumonia (CBPP)
Contagious Bovine Pleuropneumonia (CBPP) is a severe respiratory disease of cattle caused by Mycoplasma mycoides subspecies mycoides (MmmSC). It affects cattle, water buffalo, and yak, leading to significant economic losses in affected regions. Historically widespread globally, CBPP was eradicated from many European countries around 1900 but continues to pose problems in Africa and other parts of the world.
Symptoms include fever, reduced activity, decreased milk production, and a cessation of rumination. Affected animals often develop a cough, difficulty breathing, and a mucopurulent nasal discharge. In chronic cases, the bacterium can form well-defined necrotic areas in the lungs, known as sequestra. These sequestra may contain live bacteria, allowing the infection to persist and spread if the animal’s health declines.
How CBPP is Diagnosed and Spreads
Diagnosing CBPP in live animals involves several techniques, including serological tests and molecular methods. Serological tests, such as the Complement Fixation Test (CFT) and Enzyme-Linked Immunosorbent Assay (ELISA), detect antibodies produced by the animal’s immune system in response to the infection. Molecular methods, like Polymerase Chain Reaction (PCR), directly detect the genetic material of Mycoplasma mycoides from clinical samples, offering high specificity. Post-mortem diagnosis involves examining lung lesions and isolating the bacterium from affected tissues, particularly at the interface between diseased and healthy lung tissue.
CBPP spreads primarily through direct contact between infected and susceptible animals. The bacterium transmits through aerosol droplets expelled during coughing, allowing airborne spread over short distances (50 to 100 meters). Carrier animals, which show no clinical signs but harbor the bacterium, play a role in maintaining the infection within a herd and spreading it. These carriers can shed the bacteria, making disease control challenging.
Managing and Preventing CBPP
Controlling and preventing CBPP involves a multi-faceted approach, emphasizing strict biosecurity measures. Quarantine protocols for newly introduced animals and controlling animal movement are important for preventing disease introduction and spread. Rapid detection and isolation of infected animals help contain outbreaks, reducing the risk of further transmission within a herd.
Vaccination programs are also employed, though their effectiveness can vary. Available vaccines, typically live attenuated strains, offer some protection but do not always prevent infection or the carrier state. Stamping out, which involves the slaughter of infected and in-contact animals, is an effective measure used in eradication efforts, particularly in regions aiming for disease-free status. The presence of carrier animals and the bacterium’s ability to form protective biofilms make complete eradication challenging.