BACILLUS

BACILLUS

By: MJ BRIONESBSN- IIINTRODUCTIONMembers of the genus Bacillus are ubiquitous. Present in Soil, Air, Dust, & Water. Frequently isolated as CONTAMINANTS in bacteriological culture media. B. anthracis, the causative agent of ANTHRX, is the most important pathogen.B. cereus can cause FOOD POISOINING. All members are generally MOTILE except B. anthracis, which is NON-MOTILE.BacillusBacillus ClassificationAll are large Gram-positive bacilliAre aerobicForm endospores Most are found in dust and soilBacillus anthracis is the major pathogen in the group

Gram stain of Bacillus sp.

Endospores of Bacillus sp.

Bacilli are an extremely diverse group of bacteria that include both the causative agent of anthrax (Bacillus anthracis) as well as several species that synthesize important antibiotics. In addition to medical uses, bacillus spores, due to their extreme tolerance to both heat and disinfectants, are used to test heat sterilization techniques and chemical disinfectants. Bacilli are also used in the detergent manufacturing industry for their ability to synthesize important enzymes.

Bacilluscan be thermophilic, psychrophilic, acidophilic, alkaliphilic, halotolerant, or halophilic and are capable at growing at pH values, temperatures, and salt concentrations where few other organisms can survive.Clinical significance

TwoBacillusspecies are considered medically significant:B. anthracis, which causesanthrax, andB. cereus, which causesfood poisoningsimilar to that caused byStaphylococcus.[4]A third species,B. thuringiensis, is an importantinsectpathogen, and is sometimes used to control insect pests. Thetype speciesisB. subtilis, an importantmodel organism. It is also a notable food spoiler, causing ropiness in bread and related food. Some environmental and commercial strainsB. coagulansmay play a role in food spoilage of highly acidic, tomato based products.

Bacillus anthracisG+B with square cut endsForm endosporesNon-motileCapsule made of glutamic acid (a polypeptide). The capsule is not found in cultured bacteria unless the bacteria are grown on bicarbonate containing media and in the presence of increased CO concentrations.

Bacillus anthracisGrow well on ordinary lab media producing large granular colonies with a coarse texture.

B. anthracisVirulence factors Capsule helps organism to resist phagocytosis but antibodies are not protective.Exotoxin is very complex and is produced only when the bacteria is growing in animal tissues.Toxin production is mediated by a temperature sensitive plasmid.

Disease Caused by B. anthracisAnthraxAnthrax is an acute infectious disease in man & animal caused by the spore-forming B. anthracis.Anthrax is zoonotic disease Anthrax is occupational diseaseDirect person-to-person spread of anthrax is extremely unlikely to occur.

Types of AnthraxCutanoues Anthrax (Malignant Pustule)Most common form of the disease to humansIt is acquired when the spores from the soil or contaminated animal or carcass infect injured skin or mucous membrane usually in face, neck and arm

Pneumonic Anthrax (Woolsorters disease)It is results most commonly from inhalation of spore-containing dust where animal hair or hides are being handled

Intestinal AnthraxIt is analogous to cutaneous anthrax but occurs on the intestinal mucosaIntestinal anthrax is rare & occurs accidentally among butchers and in primitive societies eating meat of infected animalsBacillus anthracisClinical significanceAnthrax which is the disease caused by B. anthracis is essentially a disease of animals who acquire the organism by ingestion or inhalation of spores. The spores are extremely resistant to adverse chemicals and physical environments. They may remain a source of infection in soil for 20-30 years.Man acquires anthrax usually from contact with animal products; less commonly from working in an agricultural setting with infected animals.

Bacillus anthracisMan may acquire the organism through skin abrasions, by inhalation of spores, or by ingestion. The disease that develops depends upon the mode of transmission:Pulmonary (Woolsorters disease) Spores are inhaled and germinate in the lungs where they multiply and spread to cause a fatal septicemia or meningitis. This is the most serious form of the disease.Intestinal anthrax results from ingestion of spores. Cutaneous anthrax when organism comes in through skin abrasions;

Pulmonary anthrax

Cutaneous Anthrax

B. cereusB. cereus is a normal inhabitant of soilAlso isolated from food such as grains and spicesB. cereus causes Two Types of food poisoningEmetic form or short incubation:It is caused by heat stable enterotoxinNausea, vomiting and abdominal crampsIncubation period of 1-6 hrsIt resembles S. aureus food poisoningDiarrheal form or long incubation:It is caused by heat labile enterotoxinAbdominal cramps and diarrhea Incubation period of 8-16 hrsDiarrhea may be a small volume or profuse and wateryIt resembles food poisoning caused by Cl. perfringensIn either type, the illness usually lasts < 24 hrs after onset

Epidemiology of Anthrax in Animal and Human HostsBACILLUS CEREUS Cause of FOOD POISOINING. Ubiquitous in nature. Vegetables, milk, cereals, spices, meat & poultry. Some spores survive cooking & germinate into vegetative bacilli which produce ENTEROTOXIN that causes food poisoining. TYPES OF FOOD POISOINING 1. SHORT INCUBATION PERIOD TYPE (1-5 HRS) Characterized by acute Nausea & vomiting, 1-5 hrs after the meal. Diarrhoea is not common. It is usually associated with consumption of cooked rice, usually fried rice from Chinese restaurants.

2. Long incubation period type (8-16) Characterised by Acute abdominal pain & diarrhoea, 8-16 hrs. after consumption of contaminated food. Vomiting is rare symptom in this type.

Gastroenteritis Bacillus cereus clinical presentationIncubation period < 6 hoursSevere vomitingLasts 8-10 hoursIncubation period > 6 hoursDiarrhoea Lasts 20-36 hoursEMETIC FORM DIARRHOEAL FORM

>>> Bacillus thuringiensis parasitizes insects, and is commercially used for pest control. Although

Bacillus stearothermophilus Spores used to test efficiency of killing in autoclaves

Other Bacillus spp.

Numerous, including:B. acidocaldariusB. alcalophilusB. alveiB. aminovoransB. amyloliquefaciensB. aneurinolyticusB. anthracisB. aquaemarisB. atrophaeusB. azotoformansB. badiusB. boroniphilusB. brevisB. caldolyticusB. centrosporus

B. cereusB. circulansB. coagulansB. fastidiousB. firmusB. flavothermusB. fusiformisB. galliciensisB. globigiiB. globisporusB. infernusB. insolitusB. larvaeB. laterosporusB. lentimorbusB. lentusB. licheniformisB. maceransB. macquariensis

B. marinusB. megateriumB. mesentericusB. mucilaginosusB. mycoidesB. nattoB. pantothenticusB. pasteuriiB. polymyxaB. popilliaeB. pseudoanthracis

B. pumilusB. schlegeliiB. sphaericusB. sporothermoduransB. stearothermophilusB. subtilisB. thermoglucosidasiusB. thuringiensisB. vulgatisB. weihenstephanensis