Pasteurella multocida
Encyclopedia
Pasteurella multocida is a Gram-negative
, non-motile coccobacillus
that is penicillin
-sensitive and belongs to the Pasteurellaceae
family . It can cause avian cholera in birds and a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals and fowl harbor it as part of their normal respiratory microbiota, displaying asymptomatic colonization.
- the man in whose honor Pasteurella
is named.. The bacteria is found in many environments but the associated cholera outbreaks are usually found in central California, the Midwest, and Texas.
P. multocida causes disease in wild and domesticated animals as well as humans. The bacterium can be found in fowl, felines, canines, rabbits, cattle and pigs. In birds, P. multocida causes avian cholera; the disease has been shown to follow migration routes, especially of snow geese. The P. multocida serotype-1 is most associated with avian cholera in North America, but the bacterium does not linger in wetlands for extended periods of time. . P. multocida causes atrophic rhinitis in pigs ; it also can cause pneumonia or bovine respiratory disease in cattle . In humans, P. multocida is the most common cause of infection from animal injuries (pneumonia in cattle and pigs, atrophic rhinitis in pigs and goats, and wound infections after dog/cat-bites.) The infection usually shows as soft tissue inflammation within 24 hours. A high leukocyte and neutrophil count is typically observed, leading to an inflammatory reaction at the infection site (generally a diffuse localized cellulitis
). It can also infect other locales, such as the respiratory tract, and is known to cause regional lymphadenopathy (swelling of the lymph nodes). In more serious cases, a bacteremia
can result, causing an osteomyelitis
or endocarditis
. The bacteria may also cross the blood-brain barrier
and cause meningitis
.
encodes the toxin responsible for most P. multocida virulence factors. This toxin activates Rho GTPase
s, which bind and hydrolyze GTP, and are important in actin stress fiber formation. Formation of stress fibers may aid in the endocytosis of P. multocida. The host cell cycle is also modulated by the toxin, which can act as an intracellular mitogen
. P. multocida has been observed invading and replicating inside host amoebae, causing lysis in the host. P. multocida will grow at 37 degrees Celsius on blood or chocolate agar
, but will not grow on MacConkey agar
. Colony growth is accompanied by a characteristic "mousy" odor due to metabolic products.
Being a facultative anaerobe, it is oxidase-positive
and catalase-positive
, and can also ferment
a large number carbohydrates in anaerobic conditions.. The survival of P. multocida bacteria has also been shown to be increased by the addition of salt into its environment. Levels of sucrose and pH also have been shown to have minor effects on the bacterium’s survival.
This bacterium can be effectively treated with beta-lactam antibiotics, which inhibit cell wall synthesis. It can also be treated with fluoroquinolones or tetracyclines; fluoroquinolones inhibit bacterial DNA synthesis
and tetracyclines interfere with protein synthesis
by binding to the bacterial 30S ribosomal
subunit. Despite poor in vitro susceptibility results, macrolides (binding to the ribosome) also can be applied certainly in the case of pulmonary complications. Due to the polymicrobial etiology of P. multocida infections, treatment requires the use of antimicrobials targeted at the elimination of both aerobic and anaerobic gram negative bacteria. As a result, amoxicillin-clavulanate (a beta-lactamase inhibitor/penicillin combination) is seen as the treatment of choice.
Other research is being done on the effects of protein, pH, temperature, NaCl and sucrose on P. multocida development and survival. The research seems to show that the bacteria survive better in waters that are 18 degrees Celsius compared to 2 degrees Celsius. The addition of NaCl by 0.5% also aided the bacterium’s survival, while the sucrose and pH levels had minor effects as well. . Ongoing research has also been done on the response of P. multocida to the host environment. These tests use DNA microarrays and proteomics techniques. P. multocida-directed mutants have been tested for their ability to produce disease. Findings seem to indicate that the bacteria occupy host niches that force them to change their gene expression for energy metabolism, uptake of iron, amino acids and other nutrients. “In vitro” experiments show the responses of the bacteria to low iron and different iron sources, such as transferring and hemoglobin. P. multocida genes that are upregulated in times of infection are usually involved in nutrient uptake and metabolism. This shows that true virulence genes may only be expressed during the early stages of infection.
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
, non-motile coccobacillus
Coccobacillus
A coccobacillus is a type of rod-shaped bacteria. The word coccobacillus reflects an intermediate shape between coccus and bacillus . Coccobacilli rods are so short and wide that they resemble cocci. Haemophilus influenzae and Chlamydia trachomatis are coccobacilli...
that is penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
-sensitive and belongs to the Pasteurellaceae
Pasteurellaceae
Pasteurellaceae comprise a large and diverse family of Gram-negative Proteobacteria with members ranging from important pathogens such as Haemophilus influenzae to commensals of the animal and human mucosa. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the...
family . It can cause avian cholera in birds and a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals and fowl harbor it as part of their normal respiratory microbiota, displaying asymptomatic colonization.
History
Pasteurella multocida was first found in 1878 in cholera-infected birds. However, it was not isolated until 1880, by Louis PasteurLouis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...
- the man in whose honor Pasteurella
Pasteurella
Pasteurella is a genus of Gram-negative, facultatively anaerobic bacteria. Pasteurella species are non-motile and pleomorphic. Most species are catalase-positive and oxidase-positive....
is named.. The bacteria is found in many environments but the associated cholera outbreaks are usually found in central California, the Midwest, and Texas.
Disease
- See: PasteurellosisPasteurellosisPasteurellosis is an infection with a species of the bacteria genus Pasteurella, which is found in humans and animals.Pasteurella multocida is carried in mouth and respiratory tract of several animals, notably cats. It is a small Gram negative bacillus with bipolar staining by Wayson stain...
P. multocida causes disease in wild and domesticated animals as well as humans. The bacterium can be found in fowl, felines, canines, rabbits, cattle and pigs. In birds, P. multocida causes avian cholera; the disease has been shown to follow migration routes, especially of snow geese. The P. multocida serotype-1 is most associated with avian cholera in North America, but the bacterium does not linger in wetlands for extended periods of time. . P. multocida causes atrophic rhinitis in pigs ; it also can cause pneumonia or bovine respiratory disease in cattle . In humans, P. multocida is the most common cause of infection from animal injuries (pneumonia in cattle and pigs, atrophic rhinitis in pigs and goats, and wound infections after dog/cat-bites.) The infection usually shows as soft tissue inflammation within 24 hours. A high leukocyte and neutrophil count is typically observed, leading to an inflammatory reaction at the infection site (generally a diffuse localized cellulitis
Cellulitis
Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by exogenous bacteria, and often occurs where the skin has previously been broken: cracks in the skin, cuts, blisters,...
). It can also infect other locales, such as the respiratory tract, and is known to cause regional lymphadenopathy (swelling of the lymph nodes). In more serious cases, a bacteremia
Bacteremia
Bacteremia is the presence of bacteria in the blood. The blood is normally a sterile environment, so the detection of bacteria in the blood is always abnormal....
can result, causing an osteomyelitis
Osteomyelitis
Osteomyelitis simply means an infection of the bone or bone marrow...
or endocarditis
Endocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
. The bacteria may also cross the blood-brain barrier
Blood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
and cause meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
.
Virulence, culturing, and metabolism
A bacteriophageBacteriophage
A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...
encodes the toxin responsible for most P. multocida virulence factors. This toxin activates Rho GTPase
GTPase
GTPases are a large family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate . The GTP binding and hydrolysis takes place in the highly conserved G domain common to all GTPases.-Functions:...
s, which bind and hydrolyze GTP, and are important in actin stress fiber formation. Formation of stress fibers may aid in the endocytosis of P. multocida. The host cell cycle is also modulated by the toxin, which can act as an intracellular mitogen
Mitogen
A mitogen is a chemical substance that encourages a cell to commence cell division, triggering mitosis. A mitogen is usually some form of a protein.Mitogenesis is the induction of mitosis, typically via a mitogen....
. P. multocida has been observed invading and replicating inside host amoebae, causing lysis in the host. P. multocida will grow at 37 degrees Celsius on blood or chocolate agar
Chocolate agar
Chocolate agar - is a non-selective, enriched growth medium. It is a variant of the blood agar plate. It contains red blood cells, which have been lysed by heating very slowly to 56 °C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae...
, but will not grow on MacConkey agar
MacConkey agar
MacConkey agar is a culture medium designed to grow Gram-negative bacteria and stain them for lactose fermentation.-Contents:It contains bile salts MacConkey agar is a culture medium designed to grow Gram-negative bacteria and stain them for lactose fermentation.-Contents:It contains bile salts...
. Colony growth is accompanied by a characteristic "mousy" odor due to metabolic products.
Being a facultative anaerobe, it is oxidase-positive
Oxidase test
The oxidase test is a test used in microbiology to determine if a bacterium produces certain cytochrome c oxidases. It uses disks impregnated with a reagent such as N,N,N′,N′-tetramethyl-p-phenylenediamine or N,N-Dimethyl-p-phenylenediamine , which is also a redox indicator...
and catalase-positive
Catalase
Catalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...
, and can also ferment
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
a large number carbohydrates in anaerobic conditions.. The survival of P. multocida bacteria has also been shown to be increased by the addition of salt into its environment. Levels of sucrose and pH also have been shown to have minor effects on the bacterium’s survival.
Diagnosis and Treatment
Diagnosis of the bacterium was traditionally based on clinical findings, culture and seriological testing, but false negatives have been a problem due to easy death of P. multocida. And serology cannot differentiate between current infection and previous exposure. The quickest and most accurate method for confirming an active P. multocida infection is molecular detection using PCR.This bacterium can be effectively treated with beta-lactam antibiotics, which inhibit cell wall synthesis. It can also be treated with fluoroquinolones or tetracyclines; fluoroquinolones inhibit bacterial DNA synthesis
DNA synthesis
DNA synthesis commonly refers to:*DNA replication - DNA biosynthesis *Polymerase chain reaction - enzymatic DNA synthesis *Oligonucleotide synthesis - chemical synthesis of nucleic acids...
and tetracyclines interfere with protein synthesis
Peptide synthesis
In organic chemistry, peptide synthesis is the production of peptides, which are organic compounds in which multiple amino acids are linked via amide bonds which are also known as peptide bonds...
by binding to the bacterial 30S ribosomal
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
subunit. Despite poor in vitro susceptibility results, macrolides (binding to the ribosome) also can be applied certainly in the case of pulmonary complications. Due to the polymicrobial etiology of P. multocida infections, treatment requires the use of antimicrobials targeted at the elimination of both aerobic and anaerobic gram negative bacteria. As a result, amoxicillin-clavulanate (a beta-lactamase inhibitor/penicillin combination) is seen as the treatment of choice.
Current Research
P. multocida mutants are being researched for their ability to cause diseases. “In vitro” experiments show that the bacteria responds to low iron. Vaccination against progressive atrophic rhinitis was developed by using a recombinant derivative of P. multocida toxin. The vaccination was tested on pregnant giltsin (sows without previous litters). The piglets that were born were inoculated, while the piglets born to non-vaccinated mothers developed atrophic rhinitis.Other research is being done on the effects of protein, pH, temperature, NaCl and sucrose on P. multocida development and survival. The research seems to show that the bacteria survive better in waters that are 18 degrees Celsius compared to 2 degrees Celsius. The addition of NaCl by 0.5% also aided the bacterium’s survival, while the sucrose and pH levels had minor effects as well. . Ongoing research has also been done on the response of P. multocida to the host environment. These tests use DNA microarrays and proteomics techniques. P. multocida-directed mutants have been tested for their ability to produce disease. Findings seem to indicate that the bacteria occupy host niches that force them to change their gene expression for energy metabolism, uptake of iron, amino acids and other nutrients. “In vitro” experiments show the responses of the bacteria to low iron and different iron sources, such as transferring and hemoglobin. P. multocida genes that are upregulated in times of infection are usually involved in nutrient uptake and metabolism. This shows that true virulence genes may only be expressed during the early stages of infection.