Bacillus is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum Bacillota, with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural Bacilli is the name of the class of bacteria to which this genus belongs. Bacillus species can be either obligate aerobes which are dependent on oxygen, or facultative anaerobes which can survive in the absence of oxygen. Cultured Bacillus species test positive for the enzyme catalase if oxygen has been used or is present.
Salmonella is a genus of rod-shaped (bacillus) gram-negative bacteria of the family Enterobacteriaceae. The two known species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,650 serotypes. Salmonella was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon.
Clostridium perfringens is a Gram-positive, bacillus (rod-shaped), anaerobic, spore-forming pathogenic bacterium of the genus Clostridium. C. perfringens is ever-present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil. It has the shortest reported generation time of any organism at 6.3 minutes in thioglycolate medium.
Vibrio vulnificus is a species of Gram-negative, motile, curved rod-shaped (vibrio), pathogenic bacteria of the genus Vibrio. Present in marine environments such as estuaries, brackish ponds, or coastal areas, V. vulnificus is related to V. cholerae, the causative agent of cholera. At least one strain of V. vulnificus is bioluminescent. Increasing seasonal ocean temperatures and low-salt marine environments like estuaries favor a greater concentration of Vibrio within filter-feeding shellfish; V. vulnificus infections in the Eastern United States have increased eightfold from 1988–2018.
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus Bacillus, B. subtilis is rod-shaped, and can form a tough, protective endospore, allowing it to tolerate extreme environmental conditions. B. subtilis has historically been classified as an obligate aerobe, though evidence exists that it is a facultative anaerobe. B. subtilis is considered the best studied Gram-positive bacterium and a model organism to study bacterial chromosome replication and cell differentiation. It is one of the bacterial champions in secreted enzyme production and used on an industrial scale by biotechnology companies.
Vibrio parahaemolyticus (V. parahaemolyticus) is a curved, rod-shaped, Gram-negative bacterial species found in the sea and in estuaries which, when ingested, may cause gastrointestinal illness in humans. V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores. Like other members of the genus Vibrio, this species is motile, with a single, polar flagellum.
Saint Martin Island is a small island in the northeastern part of the Bay of Bengal, about 9 km south of the tip of the Cox's Bazar-Teknaf peninsula, and forming the southernmost part of Bangladesh. There is a small adjoining island that is separated at high tide, called Chera Dwip. It is about 8 kilometres west of the northwest coast of Myanmar, at the mouth of the Naf River.
Staphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiota and also found in marine sponges. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to form biofilms that grow on these devices. Being part of the normal skin microbiota, S. epidermidis is a frequent contaminant of specimens sent to the diagnostic laboratory.
Shigella flexneri is a species of Gram-negative bacteria in the genus Shigella that can cause diarrhea in humans. Several different serogroups of Shigella are described; S. flexneri belongs to group B. S. flexneri infections can usually be treated with antibiotics, although some strains have become resistant. Less severe cases are not usually treated because they become more resistant in the future. Shigella are closely related to Escherichia coli, but can be differentiated from E.coli based on pathogenicity, physiology and serology.
Aeromonas is a genus of Gram-negative, facultative anaerobic, rod-shaped, bacteria that morphologically resemble members of the family Enterobacteriaceae. Most of the 14 described species have been associated with human diseases. The most important pathogens are A. hydrophila, A. caviae, and A. veronii biovar sobria. The organisms are ubiquitous in fresh and brackish water.
Aeromonas veronii is a Gram-negative, rod-shaped bacterium found in fresh water and in association with animals. In humans A. veronii can cause diseases ranging from wound infections and diarrhea to sepsis in immunocompromised patients. In leeches, this bacterium is thought to function as a symbiote aiding in the digestion of blood, provision of nutrients, or preventing other bacteria from growing. Humans treated with medicinal leeches after vascular surgery can be at risk for infection from A. veronii and are commonly placed on prophylactic antibiotics. Most commonly ciprofloxacin is used but there have been reports of resistant strains leading to infection.
Photobacterium is a genus of gram-negative, oxidase positive and catalase positive bacteria in the family Vibrionaceae. Members of the genus are bioluminescent, that is they have the ability to emit light.
Vibrio alginolyticus is a Gram-negative marine bacterium. It is medically important since it causes otitis and wound infection. It is also present in the bodies of animals such as pufferfish, where it is responsible for the production of the potent neurotoxin, tetrodotoxin.
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.
Aeromonas salmonicida is a pathogenic bacterium that severely impacts salmonid populations and other species. It was first discovered in a Bavarian brown trout hatchery by Emmerich and Weibel in 1894. Aeromonas salmonicida's ability to infect a variety of hosts, multiply, and adapt, make it a prime virulent bacterium. A. salmonicida is an etiological agent for furunculosis, a disease that causes sepsis, haemorrhages, muscle lesions, inflammation of the lower intestine, spleen enlargement, and death in freshwater fish populations. It is found worldwide with the exception of South America. The major route of contamination is poor water quality; however, it can also be associated stress factors such as overcrowding, high temperatures, and trauma. Spawning and smolting fish are prime victims of furunculosis due to their immunocompromised state of being.
Streptococcus iniae is a species of Gram-positive, sphere-shaped bacterium belonging to the genus Streptococcus. Since its isolation from an Amazon freshwater dolphin in the 1970s, S. iniae has emerged as a leading fish pathogen in aquaculture operations worldwide, resulting in over US$100M in annual losses. Since its discovery, S. iniae infections have been reported in at least 27 species of cultured or wild fish from around the world. Freshwater and saltwater fish including tilapia, red drum, hybrid striped bass, and rainbow trout are among those susceptible to infection by S. iniae. Infections in fish manifest as meningoencephalitis, skin lesions, and septicemia.
Aeromonas dhakensis is a Gram-negative bacterium first isolated from aquariums in Portugal in 2005. The species is globally distributed in aquatic environments, like other species in the genus Aeromonas.
Providencia rettgeri, is a Gram negative bacterium that is commonly found in both water and land environments. P. rettgeri is in the genus Providencia, along with Providencia stuartii, Providencia alcalifaciens, and Providencia rustigianii. P. rettgeri can be incubated at 37 °C in nutrient agar or nutrient broth. It was first discovered in 1904 after a waterfowl epidemic. Strains of the species have also been isolated from nematodes of the genus Heterorhabditis. Providencia rettgeri also found in marine environment.
Laribacter hongkongensis is a species of bacteria. It is facultatively anaerobic, non-sporulating, gram-negative, seagull- or spiral rod-shaped. It is a potential human pathogen. Laribacter hongkongensis has been isolated from human cases of diarrhea, but its role in causing diarrhea is unproven, even though it has been hypothesized. Additional studies are needed to better define its role as a possible enteric pathogen. These should include: case control studies designed to differentiate infection from colonization-transient passage, fulfilling Koch's postulates and Bradford-Hill's criteria on association vs. causation, possible virulence factors, animal models, host factors, antibody responses based on serodiagnostic testing, and human volunteer studies. The lessons learned from trying to establish the etiological role of the bacteria genera Aeromonas, Plesiomonas, and Edwardsiella in human diarrhea seem especially applicable for Laribacter. All four genera are isolated from extraintestinal infections, are apparently found in the aquatic environment, and epidemiological associations include eating fish and foreign travel. Even after over 50 years’ experience with the former three genera their etiological role in an individual case of human diarrhea is difficult to determine without extensive studies. For all four of these genera the critical issue will be differentiating infection from colonization or transient passage in the intestine.
Bacillus sonorensis is a species of bacteria with type strain L87-10T. Its genome has been sequenced.
