Microbiology - Bacteria 1 PDF

BACTERIA I: “ORDINARY” GRAM-NEGATIVE BACTERIA General Characteristics: 1. Most have a relatively simple morphology and celluar arrangement 2. They do not form complex structures 3. Cells are not arranged in trichomes 4. Reproduce mainly by transverse binary fission 5. They are mainly...

BACTERIA I: “ORDINARY” GRAM-NEGATIVE BACTERIA General Characteristics: 1. Most have a relatively simple morphology and celluar arrangement 2. They do not form complex structures 3. Cells are not arranged in trichomes 4. Reproduce mainly by transverse binary fission 5. They are mainly heterotrophic 6. Could be saprophytes or parasites 7. Cold be highly pathogenic or opportunistic pathogens A. The SPIROCHETES Distinguishing features: 1. Helical shape 2. Ability to twist or contort their shape (flexibility) 3. The occurrence of a special kind of flagella termed periplasmic flagella Other features 1. They cannot be easily seen by light microscopy even when gram-stained; however dark field microscopy provides efficient contrast 2. Swims best in viscous media Common species 1. Treponema pallidum - causes syphilis in humans Habitat: mouth, intestinal tract and genital areas of humans and animals Oxygen relationship: anaerobic, and microaerophilic (requires less oxygen than atmosphere) T. pallidum is a motile spirochete that is generally acquired by close sexual contact, entering the host via breaches in squamous or columnar epithelium. The organism can also be transmitted to a fetus by transplacental passage during the later stages of pregnancy, giving rise to congenital syphilis. The helical structure of T. pallidum allows it to move in a corkscrew motion through a viscous medium such as mucus. It gains access to host’s blood and lymph systems through tissue and mucous membranes. Syphilis. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and tertiary). The primary stage classically presents with a single chancre (a firm, painless, non-itchy skin ulceration), secondary syphilis with a diffuse rash which frequently involves the palms of the hands and soles of the feet, latent syphilis with little to no symptoms, and tertiary syphilis with gummas, neurological, or cardiac symptoms. It has, however, been known as “the great imitator” due to its frequent atypical presentations. Diagnosis is usually via blood tests; however, the bacteria can also be visualized under a microscope. Syphilis can be effectively treated with antibiotics, specifically intramuscular penicillin G, and in those who are allergic, ceftriaxone is recommended. 2. Borellia recurrentis – Pathogenic causing louseborne or tickborne relapsing fever in humans Habitat: Parasites of wild rodents and small mammals, and also of the arthropods associated with these animals Oxygen relationship: microaerophilic The body louse (Pediculus humanus humanus, sometimes called Pediculus humanus corporis) is a louse which infests humans. The condition of being infested with head lice, body lice, or pubic lice is known as pediculosis. It is indistinguishable in appearance from Pediculus humanus capitis (the head louse. In particular, body lice have evolved to attach their eggs to clothes, whereas head lice attach their eggs to the base of hairs. Body lice frequently lay their eggs on or near the seams of clothing. Body lice must feed on blood and usually only move to the skin to feed. Body lice infestations can spread rapidly under crowded living conditions where hygiene is poor (homeless, refugees, victims of war or natural disasters). Body lice are spread through prolonged direct physical contact with a person who has body lice or through contact with articles such as clothing, beds, bed linens, or towels that have been in contact with an infested person. Body lice are a nuisance in themselves and cause intense itching. They are however, also vectors (transmitters) of other diseases. Body lice can spread epidemic typhus, trench fever, and louse-borne relapsing fever. Outbreaks of this relapsing fever still occur during times of war, civil unrest, natural or man-made disasters, and in prisons where people live together in unsanitary conditions. Louse-borne relapsing fever. Signs include severe jaundice, severe change in mental status, severe bleeding, and prolonged QT interval on ECG. Lice that feed on infected humans acquire the Borrelia organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. B. recurrentis infects the person via mucous membranes and then invades the bloodstream. No animal reservoir exist Most people who are infected get sick around 5–15 days after they are bitten by the tick. The symptoms may include a sudden fever, chills, headaches, and muscle or joint aches, and nausea; a rash may also occur. These symptoms continue for 2–9 days, then disappear. This cycle may continue for several weeks if the person is not treated. Relapsing Fever is easily treated with 1–2 weeks of antibiotics. Most people improve within 24 hours of starting antibiotics. Complications and death due to relapsing fever are rare. 3. Leptospira interrogans – parasites of wild; causes leptospirosis It is a species of Leptospira, which is a Gram-negative obligate aerobe spirochete, with periplasmic flagellum. These reside in alkaline water; alkaline soil and can survive in these for 3 months or longer. They also could be found in urine. Leptospirosis Transmission:  By the urine of an infected animal and is contagious as long as it is still moist splashing contaminated water into eyes or nose, or exposing open wounds to infected water  Although rats, mice and moles are important primary hosts, a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, possums, skunks, and certain marine mammals are able to carry and transmit the disease as secondary hosts. House dogs contracting leptospirosis apparently from licking the urine of infected mice that entered the house  By the semen of infected animals  Slaughterhouse workers may contract the disease through contact with infected blood or body fluids  Type of habitats most likely to carry infective bacteria is muddy riverbanks, ditches, gullies, and muddy livestock rearing areas where there is regular passage of either wild or farm mammals.  Direct correlation between the amount of rainfall and the incidence of leptospirosis, making it seasonal in temperate climates and year-round in tropical climates  Through contact with water, food, or soil containing urine from these infected animals  Common among water-sport enthusiasts in specific areas as prolonged immersion in water is known to promote the entry of the bacteria: Surfers, whitewater paddlers, rowers  Occupations at risk include veterinarians, slaughterhouse workers, farmers, sewer workers, and people working on derelict buildings. are also sometimes known to contract the disease Symptoms:  Begins with flu-like symptoms (fever, chills, myalgias, intense headache); may resemble pneumonia. The symptoms in humans appear after a 4–14 day incubation period.  Second phase is characterized by meningitis, liver damage (causing jaundice), and renal failure  The absence of jaundice does not eliminate the possibility of leptospirosis, and its presence could indicate hepatitis or other liver pathology rather than leptospirosis. Vomiting, fever, failure to eat, reduced urine output, unusually dark or brown urine, and lethargy are also indications of the disease B. AEORBIC/MICROAEROPHILIC, MOTILE, HELICAL/VIBRIOID, GRAM-NEGATIVE BACTERIA Characteristics 1. The cells are rigid (unlike spirochetes) and range from vibrioid (having less than one turn or twist) to helical (having one to many turns or twists) 2. They swim by means of polar flagella 3. They are aerobic or microaerophilic 4. They attack few or no carbohydrates Campylobacter jejuni  is a species of curved, helical-shaped, non-spore forming, Gram- negative, microaerophilic bacteria commonly found in animal feces. It is one of the most common causes of human gastroenteritis in the world  occurs in the reproductive organs, intestinal tract and oral cavity of humans and other animals  commonly associated with poultry, and it naturally colonizes he  digestive tract of many bird species; also common in cattle, and although it is normally a harmless commensal of the gastrointestinal tract in these animals  Contaminated drinking water and unpasteurized milk provide an efficient means for distribution  Contaminated food is a major source of isolated infections, with incorrectly prepared meat and poultry normally the source of the bacteria. Campylobacteriosis  Food poisoning caused by Campylobacter species can be severely debilitating, but is rarely life- threatening.  It has been linked with subsequent development of Guillain-Barré syndrome (GBS, symptoms of ascending paralysis), which usually develops two to three weeks after the initial illness  C jejuni produce a cholera-like enterotoxin, which is important in the watery diarrhea observed in infections. The organism produces diffuse, bloody, edematous, and exudative enteritis  fecal-oral, person-to-person sexual contact, ingestion of contaminated food (generally unpasteurized (raw) milk and undercooked or poorly handled poultry), and waterborne (i.e., through contaminated drinking water). C. AEROBIC, GRAM-NEGATIVE RODS AND COCCI General Features: 1. Cells are mainly straight or slightly curved (but not helical rods), but some are cocci 2. They have a strictly respiratory type of metabolism Common Species Pseudomonas aeruginosa  Widely distributed in soil and water, frequently present in the normal intestinal flora and on the skin of humans  Grow not only in normal atmosphere, but in hypoxic atmospheres and anerobically  uses a wide range of organic material for food; in animals, the versatility enables the organism to infect damaged tissues or those with reduced immunity  may also be found on and in medical equipment, including catheters, causing cross-infections in hospitals and clinics. It is implicated in hot-tub rash (dermatitis).  Can cause spoilage of meat and other foods  It is also able to decompose hydrocarbons and has been used to break down tarballs and oil from oil spills Infection due to P. aeruginosa  Pathogenic when introduced to damaged tissues  Common cause of infections of burn injuries and of the external ear (otitis externa), and is the most frequent colonizer of medical devices (e.g., catheters).  (One out of ten) Nosocomial diseases is due to P. aeruginosa: cystic fibrosis patients, dermatitis, burn infections, post- operative infections, skin lesion ecthyma gangrenosum, puncture wounds of the foot via foam padding found in tennis shoes.   symptoms of infections are generalized inflammation and sepsis; If colonization occurs in critical body organs, such as the lungs, the urinary tract, and kidneys, the results can be fatal;  Symptoms of Pseudomonas aeruginosa infection, depends on the part of the body that is infected. Fever, fatigue, muscle and joint pain are symptoms of pseudomonas bacteremia. The following list gives the respective symptoms of each infection, o Bone infection: Swollen infected part, redness. o Ear infection: Pain in the ear, reduced ability to hear, facial paralysis. o Eye infection: Pain in the eye, reduced vision, swollen eyelids. o Cystic fibrosis: Cough, reduced appetite, fast breathing, enlargement of abdomen. o Skin infections: Ulcer that can result in bleeding. Oil Tar Bioremediation  A tarball is a blob of petroleum which has been weathered after floating in the ocean. Tarballs are an aquatic pollutant in most environments, although they can occur naturally and as such are not always associated with oil spills.  Tarball concentration and features have been used to assess the extent of oil spills and their composition can also be used to identify their sources of origin. They are slowly decomposed by microorganisms, including Chromobacterium violaceum, Cladosporium resinae, Bacillus submarinus, Micrococcus varians, Pseudomonas aeruginosa, Candida marina and Saccharomyces estuari. Legionella  Opportunistic pathogens to humans causing Legionnaire’s disease or Legionellosis, notably pneumophilia  Legionella transmission is via aerosols – the inhalation of mist droplets containing the bacteria Streams, water from air conditioning, cooling towers and moist soil adjacent to a body of water, swimming pools (especially in Scandinavian countries, domestic hot-water systems, fountains, and similar disseminators that tap into a public water supply  Natural sources of Legionella include freshwater ponds and creeks  Legionellosis symptos - usually have fever, chills, and a cough, which may be dry or may produce sputum. Some patients also have muscle aches, headache, tiredness, loss of appetite, loss of coordination (ataxia), and occasionally diarrhea and vomiting. Neisseria gonorrhea  Gram-negative facultatively intracellular coffee bean- shaped diplococci bacteria responsible for the sexually transmitted infection gonorrhea  Parasites that inhabit the mucous membranes of humans  Motile (twitching motility); Pili extend and attach to a substrate which signals the pilus to retract, dragging the cell forward. N. gonorrhoeae are able to pull 100,000 times their own weight and it has been claimed that the pili used to do so are the strongest biological motor known to date Gonorrhea  Symptoms of infection with N. gonorrhoeae differ depending on the site of infection. Note also that 10% of infected males and 80% of infected females are asymptomatic.  Infection of the genitals can result in a purulent (or pus-like) discharge from the genitals which may be foul smelling. Symptoms may include inflammation, redness, swelling, and dysuria.  Gonorrhea can also cause conjunctivitis, pharyngitis, proctitis or urethritis, prostatitis and orchitis  Conjunctivitis is common in neonates (newborns), and silver nitrate or antibiotics are often applied to their eyes as a preventive measure against gonorrhea. Neonatal gonorrheal conjunctivitis is contracted when the infant is exposed to N. gonorrhea in the birth canal and can lead to corneal scarring or perforation, resulting in blindness in the neonate.  Disseminated N. gonorrhea infections can occur, resulting in endocarditis, meningitis or gonococcal dermatitis-arthritis syndrome.  Infection of the genitals in females with N. gonorrhea can result in pelvic inflammatory disease if left untreated, which can result in infertility. Pelvic inflammatory disease results if N. gonorrhea travels into the pelvic peritoneum (via the cervix, endometrium and fallopian tubes). Infertility is caused by inflammation and scarring of the fallopian tube. Infertility is a risk to 10 to 20% of the females infected with N. gonorrhea Acinetobacter  Saprophytes that occur in water, sewage and soil where they contribute to the mineralization of, for example, aromatic compounds  also opportunistic human pathogens that cause variety of infections particularly in hospitalized patients Acinetobacter baumannii  Species of the genus Acinetobacter are non-motile and oxidase-negative, are strictly aerobic nonfermentative Gram-negative bacilli. They show preponderantly a coccobacillary morphology and occur in pairs under magnification  Acinetobacter spp are widely distributed in nature. They are able to survive on various surfaces (both moist and dry) in the hospital environment, thereby being a major source of infection in debilitated patients. Occasional strains are isolated from foodsuffs, and some are able to survive on various medical equipment and even on healthy human skin hundreds of Acinetobacter colonies were discovered on an everyday kitchen sponge.  In drinking water, Acinetobacter have been shown to aggregate bacteria that otherwise do not form aggregates. Bioremediation  Some strains of this genus are known to be involved in biodegradation of a number of different pollutants such as biphenyl and chlorinated biphenyl, amino acids (analine), phenol, benzoate, crude oil, acetonitrile, and in the removal of phosphate or heavy metals. Acinetobacter strains are also well represented among fermentable bacteria for the production of a number of extra- and-intracellular economic products such as lipases, proteases, cyanophycine, bioemulsifiers and several kinds of biopolymers.  Xenobiotics pollutants such as benzene, toluene, phenol and styrene, as well as halogenated organic compounds such as pentachlorophenol and polychlorinated biphenyls are often present in waste streams in fairly low concentrations. They may also be present in larger quantities as  spills, or in the soil and water at abandoned industrial sites. These compounds are generally highly toxic and exceedingly difficult to dispose of. Among phenol degraders are several strains of Acinetobacter, which can use it as a sole energy and carbon source D. FACULTATIVELY ANAEROBIC GRAM-NEGATIVE RODS 1. Family Enterobacteriaciae  normal flora of the gut flora found in the intestines of humans and other animals, while others are found in water or soil, or are parasites on a variety of different animals and plants  Rod-shaped, and are typically 1-5 μm in length, Gram-negative stains, facultative anaerobes, fermenting sugars to produce lactic acid and various other end products. Most also reduce nitrate to nitrite  Most are peritrichous , but a few genera are non-motile. They are non-spore forming  Type I fimbriae for adhesion of the bacterial cells to their hosts. Some produce endotoxins which cause systemic infection into the blood stream when all the dead bacterial cells release their endotoxins. This is known as endotoxic shock and can lead to instant death Enterobacter - Gram-negative, facultatively-anaerobic, rod-shaped bacteria - Several strains are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts and in those who are on mechanical ventilation. - The urinary and respiratory tracts are the most common sites of infection. It is also a fecal coliform, along with Escherichia. o E. aerogenes  Generally found in the human gastrointestinal tract and does not generally cause disease in healthy individuals.  Occur in human and animal feces and found to live in water, various wastes, hygienic chemicals, and soil and also in meat, plants and vegetables  a nosocomial and pathogenic bacterium that causes opportunistic infections o E. cloacae  has been used in a bioreactor based method for the biodegradation of explosives and in the biological control of plant diseases  associated with urinary tract and respiratory tract infections. Escherichia - Gram-negative, non-spore forming, facultatively anaerobic, rod-shaped bacteria - Inhabitants of the gastrointestinal tracts of humans and other warm-blooded animals - Escherichia species provide a portion of the microbially-derived vitamin K for their host. - many are harmless commensals, particular strains of some species are human pathogens and are known as the most common cause of urinary tract infections, gastrointestinal disease, ranging from simple diarrhea to dysentery-like conditions o E. coli  Commonly found in the lower intestine of warm- blooded organisms (endotherms).  Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans   The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2, and by preventing the establishment of pathogenic bacteria within the intestine.  E. coli and related bacteria constitute about 0.1% of gut flora,  fecal-oral transmission  Cells are able to survive outside the body for a limited amount of time, which makes them ideal indicator organisms to test environmental samples for fecal contamination.  Can be grown easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years.  E. coli is the most widely studied prokaryotic model organism, and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA.  Role as normal microbiota: E. coli normally colonizes an infant’s gastrointestinal tract within 40 hours of birth, arriving with food or water or with the individuals handling the child. In the bowel, it adheres to the mucus of the large intestine. It is the primary facultative anaerobe of the human gastrointestinal tract.  Pathogenic E. coli: Food poisoning caused by E. coli can result from eating unwashed vegetables or undercooked meat. O157:H7 is also notorious for causing serious and even life-threatening complications such as hemolytic-uremic syndrome. E. coli can harbour both heat-stable and heat-labile enterotoxins. E. coli bacteria escape the intestinal tract through a perforation (for example from an ulcer, a ruptured appendix, or due to a surgical error) and enter the abdomen; they usually cause peritonitis that can be fatal without prompt treatment. Fecal coliform as indicator of environmental quality o A fecal coliform is a facultatively-anaerobic, rod-shaped, gram-negative, non-sporulating bacterium, capable of growth in the presence of bile salts or similar surface agents, are oxidase negative, and produce acid and gas from lactose within 48 hours at 44 ± 0.5°C o Coliform bacteria include genera that originate in feces (e.g. Escherichia) as well as genera not of fecal origin (e.g. Enterobacter, Klebsiella, and Citrobacter). The assay is intended to be an indicator of fecal contamination; more specifically of E. coli which is an indicator microorganism for other pathogens that may be present in feces. Presence of fecal coliforms in water may not be directly harmful, and may indicate the presence of feces Pathogenic E. coli Enterotoxigenic E. coli ETEC strains are noninvasive, and they do not leave the intestinal lumen. ETEC (ETEC) is the leading bacterial cause of diarrhea in children in the developing world Enteropathogenic E. coli Changes in intestinal cell ultrastructure due to "attachment and effacement" (EPEC) is likely the prime cause of diarrhea in those afflicted with EPEC. Enteroinvasive E. coli Found only in humans. EIEC infection causes a syndrome that is identical to (EIEC) shigellosis, with profuse diarrhea and high fever. Enterohemorrhagic E. The most infamous member of this virotype is strain O157:H7, which causes coli (EHEC) bloody diarrhea and no fever. EHEC can cause hemolytic-uremic syndrome and sudden kidney failure. Enteroaggregative E. Found only in humans, EAEC bind to the intestinal mucosa to cause watery coli (EAEC) diarrhea without fever. EAEC are noninvasive. Citrobacter - These bacteria can be found almost everywhere in soil, water, wastewater, etc. It can also be found in the human intestine. They are rarely the source of illnesses, except for infections of the urinary tract and infant meningitis and sepsis. Yersenia - Y. pestis is pathogenic in humans, the causative agent of the plague. - Rodents are the natural reservoirs of Yersinia; less frequently other mammals serve as the host. - Infection may occur either through blood (in the case of Y. pestis) or in an alimentary fashion, occasionally via consumption of food products (especially vegetables, milk-derived products and meat) contaminated with infected urine or feces. - Yersinia may be associated with Crohn’s disease, an inflammatory autoimmune condition of the gut. Iranian sufferers of Crohn's disease were more likely to have had earlier exposure to refrigerators at home, consistent with Yersinia’s unusual ability to thrive at low temperatures. Black Death (Plague) o Nothing came close to exterminating the human species o In the 1340’s, more than 13 million died from disease in China o the plague originated in Egypt and was introduced to the rest of the world by the black rat stow-aways on trade ships ; At its peak, 10,000 to 15,000 died daily in Cairo o It was reported that half of the population of the known world died o More than 60 million people died o Nowadays, each year, 300,000 deaths world-wide due to bubonic, septicemic and pneumonic plague. o Fleas become infected by feeding on rodents, such as the chipmunks, prairie dogs, ground squirrels, mice, and other mammals that are infected with the bacteria Yersinia pestis. Fleas transmit the plague bacteria to humans and other mammals during the feeding process. The plague bacteria are maintained in the blood systems of rodents. Bubonic Plague Bubonic plague is derived from the Greek word bubo, meaning “swollen gland”. The bubos are actually very swollen lymph nodes which served as points of initial infection and most often show up in the groin, under-arm, or neck. Other symptoms make the common flu look like a kiddy ride - high fever, nausea, vomitting (possibly bloody), severe muscle/joint pain, sore throat, headache, debilitating weakness, chills. Septicemic Plague Septicemia is a severe, generalized infection - the bacteria circulate through the blood stream and can impact any organ in the body.  Pneumonic plague can be contracted two different ways - from the advancement of bubonic or septicemic plague or from coming into contact with another person or animal that has pneumonic plague. While the other forms of Yersinia plague can pass person-to-person with close contact and exchange of bodily fluid, stepping within a few feet of a person suffering pneumonic plague and taking a few unprotected breaths can be quite literally a death sentence. Modern sanitation, pest control, and antibiotics have reduced this one-time mega killer to a smaller stature on the scale of world threats, but modern man might yet feel the real bite of this beast. In the age of terrorism, Yesinia plague in aerosol (airborne) form is considered one of the most feared as a potential biological weapon. And unlike small pox and polio, this deadly disease has host colonies the world over and will very likely continue to be a threat. Salmonella - Chemoorganotrophs, obtaining their energy from oxidation and reduction reactions using organic sources, and are facultative anaerobes. Most species produce hydrogen sulfide which can readily be detected by growing them on media containing ferrous sulfate - cause illnesses like typhoid fever, paratyphoid fever, and foodborne illness - Many infections are due to ingestion of contaminated food - Salmonella typhi is adapted to humans and does not occur in animals Food Poisoning Salmonella Salmonella enters through the digestive tract and must be ingested in large numbers to cause disease in healthy adults, infants and young children are much more susceptible. It can survive for weeks outside a living body. Salmonella are not destroyed by freezing. Ultraviolet radiation and heat accelerate their demise; they perish after being heated to 55 °C (131 °F) for one hour, or to 60 °C (140 °F) for half an hour. To protect against Salmonella infection, it is recommended that food be heated for at least ten minutes at 75 °C (167 °F) so that the centre of the food reaches this temperature. Typhoid Fever Typhoid fever is characterized by a slowly progressive fever as high as 40 °C (104 °F), profuse sweating and gastroenteritis. Less commonly, a rash of flat, rose-colored spots may appear. Classically, the course of untreated typhoid fever is divided into four individual stages, each lasting approximately one week. In the first week, there is a slowly rising temperature with relative bradycardia, malaise, headache, and cough. A bloody nose (epistaxis) is seen in a quarter of cases and abdominal pain is also possible. Mary Mallon (1869 –1938), also known as Typhoid Mary, was the first person in the United States identified as an asymptomatic carrier of the pathogen associated with typhoid fever. She was presumed to have infected some 53 people, three of whom died, over the course of her career as a cook. She was forcibly isolated twice by public health authorities and died after nearly three decades altogether in isolation.  Sources of infection  Infected food, often gaining an unusual color, odor, or chewiness, that is then introduced into the stream of commerce;  Poor kitchen hygiene, especially problematic in institutional kitchens and restaurants because this can lead to a significant outbreak;  Excretions from either sick or infected but apparently clinically healthy people and animals (especially endangered are caregivers and animals);  Polluted surface water and standing water (such as in shower hoses or unused water dispensers);  Unhygienically thawed fowl (the meltwater contains many bacteria);  An association with reptiles (pet tortoises, snakes, iguanas and frogs, but primarily aquatic turtles) Salmonella bacteria can survive several weeks in a dry environment and several months in water thus, they are frequently found in polluted water, contamination from the excrement of carrier animals being particularly important. Aquatic vertebrates, notably birds and reptiles, are important vectors of Salmonella. Poultry, cattle, and sheep frequently being agents of contamination, salmonella can be found in food, especially in milk, meats and sometimes in eggs which have cracks Shigella - Shigella dysenteriae is the causative agent of human shigellosis only naturally found in humans and apes - Causes dysentery infection; typically via ingestion (fecal–oral contamination); dysentery that results in the destruction of the epithelial cells of the intestinal mucosa in the cecum and rectum. - The most common symptoms are diarrhea, fever, nausea, vomiting, stomach cramps and flatulence. The stool may contain blood, mucus, or pus. 2. Family Vibrionaceae  Inhabitants of fresh or salt water, several species are pathogenic  Gram-negative organisms and facultative anaerobes, capable of fermentation  Synthesize Tetrodotoxin (TTX), an ancient marine alkaloid and powerful neurotoxin (1 mg can kill an adult) that serves to protect members of an Order (biology) of fishes, the Tetraodontiformes, which include the Puffer Fish  In symbiosis with many marine organisms In the case of the Puffer fish, and other marine organisms harboring TTX producing Vibrionaceae, the symbiosis is an ancient and powerful one, providing protection against predation for the marine organisms that harbor these bacteria, while providing the bacteria a protected environment with plenty of nutrients for growth. Vibrio cholera and Cholera - comma-shaped bacterium with a polar flagellum that causes cholera in humans - Occurs in aquatic habitats with wide range of salinity but can live naturally in any environment - Symptoms of cholera: profuse painless diarrhea described as “rice water” with fishy odor, vomiting of clear fluid; usually start suddenly, one to five days after ingestion of the bacteria.  - An untreated person with cholera may produce 10–20 liters of diarrhea a day with fatal results due to dehydration (low blood pressure, wrinkled hands, sunken eyes and rapid pulse). For every symptomatic person there are 3 to 100 people who get the infection but remain asymptomatic. - Transmission o primarily due to the fecal contamination of food and water due to poor sanitation from infected individuals o Seafood from contaminated waters: oysters, mussels, etc. o Rarely spread from person to person. Vibrio parahaemolyticus - a curved, rod-shaped, Gram-negative bacterium found in brackish saltwater, which, when ingested, causes gastrointestinal illness in humans - Infection can occur via the fecal-oral route, ingestion of bacteria in raw or undercooked seafood, usually oysters, is the predominant cause the acute gastroenteritis - Wound infections also occur, but are less common than seafood-borne disease - Outbreaks tend to be concentrated along coastal regions during when higher water temperatures favor higher levels of bacteria. - Seafood most often implicated includes squid, mackerel, tuna, sardines, crab, shrimp, and bivalves like oysters and clams. - The incubation period of ~24 hours is followed by explosive, watery diarrhea accompanied by nausea, vomiting, abdominal cramps, and sometimes fever. - Swimming or working in affected areas can lead to infections of the eyes or ears and open cuts and wounds 3. Family 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 upper respiratory tract. The family includes several pathogens of vertebrates, most notably H. influenzae. This species causes several diseases in humans (though not flu, as was originally thought). Other Pasteurellaceae cause gingivitis and chancroid in humans and many others are important veterinary pathogens Haemophilus influenzae - H. influenzae are opportunistic pathogens; that is, they usually live in their host without causing disease, but cause problems only when other factors (such as a viral infection or reduced immune function) create an opportunity - Unencapsulated H. influenzae causes ear infections (otitis media), eye infections (conjunctivitis), and sinusitis in children, and is associated with pneumonia. E. THE RICKETTSIAS  non-motile, Gram-negative, non-sporeforming, highly pleomorphic bacteria that can present as cocci (0.1 μm in diameter), rods (1–4 μm long) or thread-like (10 μm long)  Obligate intracellular parasites, survival depends on entry, growth, and replication within the cytoplasm of eukaryotic host cells (typically endothelial cells).  Cannot live in artificial nutrient environments and are grown either in tissue or embryo cultures  Associated with various arthropods which may serve as major hosts or which can act as vectors for transmission of Rickettsias to vertebrates  Transmission to humans occurs via arthropod vectors (lice, fleas, ticks or mites) depending on the species.  Organisms multiply within the cytoplasm and sometimes within the nucleus of the host cells Diseases transmitted by Rickettsias Disease Description Rickettsia Species Insect/Vector Epidemic typhus- a form of typhus so also called “camp named because the fever”, “jail fever”, disease often causes “hospital fever”, epidemics following “ship fever”, wars and natural “famine fever”, disasters “putrid fever”, Body Louse “petechial fever” Rickettsia prowazekii Murine typhus or A form of typhus endemic typhus transmitted by fleas (Xenopsylla cheopis) usually on rats. Most people who are infected do not realize that they have been Rickettsia typhi Flea bitten by fleas (Xenopsylla cheopis) Scrub typhus or a form of typhus Bush typhus caused by Orientia tsutsugamushi (formerly Rickettsia tsutsugamush) found inareas of heavy scrub vegetation Orientia tsutsugamushi Chigger (Mite) Rocky Mountain remains a serious and Spotted fever – also potentially life- called “tick typhus,” threatening infectious “Tobia fever” “São disease today Paulo fever” Rickettsia rickettsii Tick F. CHLAMYDIAS  All species are Gram-negative  C. trachomatis is the cause of a Chlamydia infection commonly transmitted sexually (often referred as just “Chlamydia”) and also causes trachoma, an infectious eye disease (conjunctivitis or trachoma), spread by eye, nose, and throat secretions.  Chlamydia is known as the “Silent Epidemic” because in women, it may not cause any symptoms in 75% of cases, and can linger for months or years before being discovered G. COXIELLA  Coxiella burnetii obligate intracellular bacterial pathogen, and is the causative agent of Q fever; has similar form as Rickettsia  highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light; can survive standard disinfectants  Q fever - May be found in cattle, sheep, goats and other domestic mammals, including cats and dogs. The infection results from inhalation of a spore-like small cell variant, and from contact with the milk, urine, feces, vaginal mucus, or semen of infected animals - “At risk” occupations include, but are not limited to: veterinary personnel, stockyard workers, farmers, shearers, animal transporters, laboratory workers handling potentially infected veterinary samples or visiting abattoirs, people who cull and process kangaroos, hide (tannery) workers. - a possible biological weapon