Streptococcus zooepidemicus | |
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Streptococcus zooepidemicus colonies on blood agar | |
Scientific classification ![]() | |
Domain: | Bacteria |
Phylum: | Bacillota |
Class: | Bacilli |
Order: | Lactobacillales |
Family: | Streptococcaceae |
Genus: | Streptococcus |
Species: | S. zooepidemicus |
Binomial name | |
Streptococcus zooepidemicus | |
Streptococcus zooepidemicus is a Lancefield group C streptococcus that was first isolated in 1934 by P. R. Edwards, and named Animal pyogens A. [1] It is a mucosal commensal and opportunistic pathogen that infects several animals and humans, but most commonly isolated from the uterus of mares. It is a subspecies of Streptococcus equi , a contagious upper respiratory tract infection of horses, and shares greater than 98% DNA homology, as well as many of the same virulence factors. [2]
Streptococcus zooepidemicus are gram-positive, non-sporulating, non-motile, catalase and oxidase negative cocci. S. zooepidemicus is encapsulated, with a capsular polysaccharide containing hyaluronic acid, as well as being facultative anaerobes. [3] The cells usually form in pairs, or as long chains. When plated on agar, colonies are usually 0.5-1.5 mm in diameter, circular, and opaque colored. They also have a smooth surface and a convex elevation. Its optimal temperature of growth is 37 degrees Celsius. [4]
Hemolysis on blood agar is beta-hemolytic. It ferments D-glucose, lactose, maltose, sucrose, salicin, D-sorbitol, and starch, but is negative for others like D-mannitol, glycerol, and inulin. S. zooepidemicus is also positive for Ala-Phe-Pro, Leucine, and Tyrosine arylamidase, all of which catalyze hydrolysis of amino acid residues from amino terminus of polypeptide chains. Antibiotic wise, S. zooepidemicus is highly susceptible to Penicillin, usually give for treatment, as well as Ampicillin and Erythromycin, but is extremely resistant to Novobiocin, Optochin, and Tribrissen. [4]
The genome of S. zooepidemicus is a single circular chromosome of 2,024,171 base pairs. The G+C content of the genome is 42.59%, very close in value to S. equi, which is at the higher end of the genus for G+C content. It has 1961 predicted protein coding sequences, with an average length of 879 base pairs each, and coding for an approximate value of 292 amino acids. These coding regions make up approximately 85% of the genome. The genome has five ribosomal RNA operons, and 57 tRNAs. The overall similarity between S. zooepidemicus and S. equi, is over 92%. [5]
S. zooepidemicus also produces a variety of extracellular proteins, about 100 genes identified so far, making up 5% of the total genome. These genes coding for extracellular proteins are slightly longer in length then others, approximately 478 amino acids each. 44 of these proteins are cell wall anchored surface proteins, which is a high number for Streptococcus species. This is one of the factors that lead to the high pathogenicity of S. zooepidemicus. [5]
Known strains include: [6]
The by-products of S. zooepidemicus fermentation is hyaluronic and lactic acid. The fermentation process is regulated by the production of hyaluronic acid. When high concentrations of the hyaluronic acid by-product are present, it will inhibit the production of more fermentation product. However, this fermentation process consumes high amounts of energy due to a number of factors. These factors include hyaluronic acid being severely limited, strong competition between hyaluronic synthesis and cell growth, and lactic acid being the main by-product of fermentation; which also will inhibit the overall fermentation process. [7] Since hyaluronic acid is important for the virulence of S. zooepidemicus, as well as a valuable commercial production, hyaluronic acid production is constantly trying to be increased in industry and within the organism.
Commercial uses for hyaluronic acid include an ingredient in cosmetics, skin filler for anti-aging and lip injections, in viscosurgery, and a lubricating substance in arthritic joints. [8]
Pathogenic gram positive bacteria species express cell-wall associated proteins that interact in various ways with the extracellular environment. These are made in order to benefit the organism for survival, as well as to help with establishing infection. Attachment to the epithelium cell surfaces is a critical step in the establishment of infection, and starting colonization. Overall, S. zooepidemicus is known to be more pathogenic then the S. equi species. [9]
Some cell-surface virulence factors, which all contribute to the pathogenicity of S. zooepidemicus, include:
Streptococcus zooepidemicus is able to infect many different animals, such as horses, cows, rabbits, pigs, dogs, and cats. In animals, these symptoms can include fever, inflammation of thorax, lymph nodes, or abdomen, bronchopneumonia, sepsis, mastitis, and more. [12] In Horses, S. zooepidemicus is normal flora bacterium, but is opportunistic and therefore will infect wounds, the respiratory system, and uterine, if given the chance. In horses, which are most commonly infected, this bacterium causes an upper respiratory tract infection (along with the other symptoms). This infection causes a highly contagious and deadly disease in horses. This will be caused by spreading of nasal discharge or lymph nodes in feed troughs, bedding, etc. [12]
S. zooepidemicus, which is considered a zoonotic pathogen, has rarely been isolated in humans, and infection is usually very rare. Infections are only known to be severe in immunocompromised people, namely the elderly who spent time around horses. There has also been cases of people acquiring the pathogen from homemade or unpasteurized milk or cheese. [2] Most common symptoms of glomerulonephritis, rheumatic fever, meningitis, arthritis and more, leading to the death of several patients. [2]
Before 2017, there have been 32 reported cases of infections due to Streptococcus zooepidemicus. [13]
In 2004, a 63-year-old man developed left thigh pain and swelling, which evolved into fevers, rigors, and skin rash. Two days, he experienced vertigo and vomiting, and was emitted into the hospital where he was treated with acute labyrinthitis, followed by meningococcal sepsis. Hypertension ensued, and edema of the left thigh muscle was discovered during surgery. These treatments were continued, but the patient went into progressive organ failure, followed by muscle necrosis, and ventricular tachycardia. The patient later went into circulatory and respiratory failure, before passing away less than 48 hours after being emitted into the hospital. [14]
Muscle biopsies determined S. zooepidemicus, as well as evidence of an unidentified superantigen exotoxin, to be the cause of infection, and toxic-shock like syndrome to be the cause of death. It was always noteworthy that the patient had frequent contact with horses, pigs, and cattle. This case study specifically is interesting as it strongly suggests an unidentified novel exotoxin, possibly produced by S. zooepidemicus.
In 2008, a 59-year-old woman was admitted to the emergency room due to body weakness and lightheadedness when standing, which starting three weeks prior. Over the past couple of days before being emitted she also reported shortness of breath, as well as resting tremors, rhinorrhea, and a chronic cough. She had a vast medicine history including hypertension, diabetes, obesity, chronic kidney failure, and more. She was treated for severe orthostatic hypo-tension, but in the following days complained of symptoms, and had test results that suggested meningitis. Various symptoms continued for almost a month until a blood culture tested positive for Streptococcus zooepidemicus. The patient was treated with intravenous antibiotics for six weeks, and her condition gradually improved. The patient stated there was a horse stable on her property, but she only visited it occasionally. [15]
Streptococcus is a genus of gram-positive or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Bacillota. Cell division in streptococci occurs along a single axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.
Streptococcus pyogenes is a species of Gram-positive, aerotolerant bacteria in the genus Streptococcus. These bacteria are extracellular, and made up of non-motile and non-sporing cocci that tend to link in chains. They are clinically important for humans, as they are an infrequent, but usually pathogenic, part of the skin microbiota that can cause group A streptococcal infection. S. pyogenes is the predominant species harboring the Lancefield group A antigen, and is often called group A Streptococcus (GAS). However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen as well. Group A streptococci, when grown on blood agar, typically produce small (2–3 mm) zones of beta-hemolysis, a complete destruction of red blood cells. The name group A (beta-hemolytic) Streptococcus is thus also used.
An exotoxin is a toxin secreted by bacteria. An exotoxin can cause damage to the host by destroying cells or disrupting normal cellular metabolism. They are highly potent and can cause major damage to the host. Exotoxins may be secreted, or, similar to endotoxins, may be released during lysis of the cell. Gram negative pathogens may secrete outer membrane vesicles containing lipopolysaccharide endotoxin and some virulence proteins in the bounding membrane along with some other toxins as intra-vesicular contents, thus adding a previously unforeseen dimension to the well-known eukaryote process of membrane vesicle trafficking, which is quite active at the host–pathogen interface.
Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic member of the genus Streptococcus. S. pneumoniae cells are usually found in pairs (diplococci) and do not form spores and are non motile. As a significant human pathogenic bacterium S. pneumoniae was recognized as a major cause of pneumonia in the late 19th century, and is the subject of many humoral immunity studies.
Campylobacter jejuni is a species of pathogenic bacteria that is commonly associated with poultry, and is also often found in animal feces. This species of microbe is one of the most common causes of food poisoning in Europe and in the US, with the vast majority of cases occurring as isolated events rather than mass outbreaks. Active surveillance through the Foodborne Diseases Active Surveillance Network (FoodNet) indicates that about 20 cases are diagnosed each year for each 100,000 people in the US, while many more cases are undiagnosed or unreported; the CDC estimates a total of 1.5 million infections every year. The European Food Safety Authority reported 246,571 cases in 2018, and estimated approximately nine million cases of human campylobacteriosis per year in the European Union. In Africa, Asia, and the Middle East, data indicates that C. jejuni infections are endemic.
Rickettsia rickettsii is a Gram-negative, intracellular, cocco-bacillus bacterium that was first discovered in 1902. Having a reduced genome, the bacterium harvests nutrients from its host cell to carry out respiration, making it an organo-heterotroph. Maintenance of its genome is carried out through vertical gene transfer where specialization of the bacterium allows it to shuttle host sugars directly into its TCA cycle.
Legionella pneumophila, the primary causative agent for Legionnaire's disease, is an aerobic, pleomorphic, flagellated, non-spore-forming, Gram-negative bacterium. L. pneumophila is a intracellular parasite that preferentially infects soil amoebae and freshwater protozoa for replication. Due to L. pneumophila’s ability to thrive in water, it can grow in water filtration systems, leading to faucets, showers, and other fixtures. Aerosolized water droplets containing L. pneumophila originating from these fixtures may be inhaled by humans. Upon entry to the human respiratory tract, L. pneumophila is able to infect and reproduce within human alveolar macrophages. This causes the onset of Legionnaires' disease, also known as legionellosis. Infected humans may display symptoms such as fever, delirium, diarrhea, and decreased liver and kidney function. L. pneumophila infections can be diagnosed by a urine antigen test. The infections caused by the bacteria can be treated with fluoroquinolones and azithromycin antibiotics.
Francisella tularensis is a pathogenic species of Gram-negative coccobacillus, an aerobic bacterium. It is nonspore-forming, nonmotile, and the causative agent of tularemia, the pneumonic form of which is often lethal without treatment. It is a fastidious, facultative intracellular bacterium, which requires cysteine for growth. Due to its low infectious dose, ease of spread by aerosol, and high virulence, F. tularensis is classified as a Tier 1 Select Agent by the U.S. government, along with other potential agents of bioterrorism such as Yersinia pestis, Bacillus anthracis, and Ebola virus. When found in nature, Francisella tularensis can survive for several weeks at low temperatures in animal carcasses, soil, and water. In the laboratory, F. tularensis appears as small rods, and is grown best at 35–37 °C.
Virulence factors are cellular structures, molecules and regulatory systems that enable microbial pathogens to achieve the following:
Diphtheria toxin is an exotoxin secreted mainly by Corynebacterium diphtheriae but also by Corynebacterium ulcerans and Corynebacterium pseudotuberculosis, the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophage called corynephage β. The toxin causes the disease in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis.
Rhodococcus equi is a Gram-positive coccobacillus bacterium. The organism is commonly found in dry and dusty soil and can be important for diseases of domesticated animals. The frequency of infection can reach near 60%. R. equi is an important pathogen causing pneumonia in foals. Since 2008, R. equi has been known to infect wild boar and domestic pigs. R. equi can infect immunocompromised people, such as HIV-AIDS patients or organ transplant recipients. Rhodococcus equi infection in these populations resemble the clinical and pathological signs of advanced pulmonary tuberculosis. This organism is a facultative intracellular mycobacterial pathogen.
Streptolysins are two homogenous exotoxins from Streptococcus pyogenes. Types include streptolysin O, which is oxygen-labile, and streptolysin S, which is oxygen-stable.
Bacillus anthracis is a gram-positive and rod-shaped bacterium that causes anthrax, a deadly disease to livestock and, occasionally, to humans. It is the only permanent (obligate) pathogen within the genus Bacillus. Its infection is a type of zoonosis, as it is transmitted from animals to humans. It was discovered by a German physician Robert Koch in 1876, and became the first bacterium to be experimentally shown as a pathogen. The discovery was also the first scientific evidence for the germ theory of diseases.
Streptococcus dysgalactiae is a gram positive, beta-haemolytic, coccal bacterium belonging to the family Streptococcaceae. It is capable of infecting both humans and animals, but is most frequently encountered as a commensal of the alimentary tract, genital tract, or less commonly, as a part of the skin flora. The clinical manifestations in human disease range from superficial skin-infections and tonsillitis, to severe necrotising fasciitis and bacteraemia. The incidence of invasive disease has been reported to be rising. Several different animal species are susceptible to infection by S. dysgalactiae, but bovine mastitis and infectious arthritis in lambs have been most frequently reported.
Streptococcal pyrogenic exotoxins also known as erythrogenic toxins, are exotoxins secreted by strains of the bacterial species Streptococcus pyogenes. SpeA and speC are superantigens, which induce inflammation by nonspecifically activating T cells and stimulating the production of inflammatory cytokines. SpeB, the most abundant streptococcal extracellular protein, is a cysteine protease. Pyrogenic exotoxins are implicated as the causative agent of scarlet fever and streptococcal toxic shock syndrome. There is no consensus on the exact number of pyrogenic exotoxins. Serotypes A, B, and C are the most extensively studied and recognized by all sources, but others note up to thirteen distinct types, categorizing speF through speM as additional superantigens. Erythrogenic toxins are known to damage the plasma membranes of blood capillaries under the skin and produce a red skin rash. Past studies have shown that multiple variants of erythrogenic toxins may be produced, depending on the strain of S. pyogenes in question. Some strains may not produce a detectable toxin at all. Bacteriophage T12 infection of S. pyogenes enables the production of speA, and increases virulence.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
Purpura haemorrhagica is a rare complication of equine strangles and is caused by bleeding from capillaries which results in red spots on the skin and mucous membranes together with oedema (swelling) of the limbs and the head. Purpura haemorrhagica is more common in younger animals.
Corynebacterium pseudotuberculosis is a Gram-positive bacterium known to infect ruminants, horses - and rarely - people. It is a facultative anaerobic organism that is catalase-positive and capable of beta-hemolysis. In small ruminants, C. pseudotuberculosis causes a disease called caseous lymphadenitis, which is characterized by pyogranulomatous abscess formation. In general, the bacterium causes lesions of the skin, lymph nodes, and internal organs. A disease known as ulcerative lymphagenitis can also result from infection with C. pseudotuberculosis in the distal limbs of horses. This bacterium uses the virulence factors phospholipase D and mycolic acid to damage eukaryotic cell walls and resist phagocytic lysosomal degradation, respectively. Infection with this bacterium is often confirmed by bacterial culture of the purulent exudate. Once the diagnosis has been made, treatment of the infection can begin, but this is difficult due to the nature of the organism and the lesions it forms. Specifically, C. pseudotuberculosis is intrinsically resistant to streptomycin, with varying resistance to penicillin and neomycin depending on the strain. It has been shown to be susceptible to ampicillin, gentamicin, tetracycline, lincomycin, and chloramphenicol. Vaccines have also been produced to develop acquired immunity to this infection.
Actinobacillus equuli is a gram-negative, non-motile rod bacteria from the family Pasteurellaceae.
Microbial hyaluronic acid production refers to the process by which microorganisms, such as bacteria and yeast, are utilized in fermentation to synthesize hyaluronic acid (HA). HA is used in a wide range of medical, cosmetic, and biological products because of its high moisture retention and viscoelasticity qualities. HA had originally been extracted from rooster combs in limited quantities. However, challenges such as low yields, high production costs, and ethical issues associated with animal-derived HA has driven the development of microbial production methods for HA.
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