associated with gastritis, duodenitis, and peptic and duodenal ulcers.

Gram-negative, highly motile, oxidase-positive, strongly curved bacterium. 

microaerophilic,

produces large amounts of urease

H. pylori is found within the mucus layer overlying the gastric epithelium or adherent to its surface.

does not appear to invade the mucosa

H. pylori produces an exotoxin called vacuolating cytotoxin,

contain a 40kb pathogenicity island that encodes a Type IV secretion system which injects effector proteins into gastric epithelial cells. production of the proinflammatory cytokine IL-8.

multiple antibiotic therapy to treat ulcers and gastritis is currently under investigation, with some success.

HELICOBACTER

slender, Gram-negative,

oxidase-positive,

highly motile,

curved rod

may be S-shaped, gull-winged, or comma-shaped.

Microaerophilic

Campylobacter jejuni is a major cause of diarrheal disease in the United States.

more cases of gastrointestinal disease than Salmonella and Shigella combined.

among animals (poultry, dogs, cats, sheep, and cattle).

consumption of contaminated milk, food, and water.

bloody, muco-purulent diarrhea

fever and abdominal cramps

CAMPYLOBACTER

causes rapidly progressive wound infections after exposure to contaminated seawater,

septicemia following ingestion of raw oysters

produce mortality of 50% if antibiotic treatment is not begun soon enough. 

Vibrio vulnificus

marine vibrio that requires salt for growth.

Grows in high (8%) salt, unlike V. cholerae.

Gastroenteritis caused by these organisms typically follows ingestion of raw or improperly cooked seafood,

explosive watery diarrhea.

Pathogenic strains produce Kanagawa hemolysin.

Vibrio parahaemolyticus

profuse, watery diarrhea containing flecks of mucus (called "rice-water" stool), but

no blood or inflammatory cells

intoxication of the intestinal epithelial cells.

powerful enterotoxin which induces a secretory diarrhea

Vibrio cholerae

similar to Enterobacteriaceae

facultative Gram-negative curved rods motile by means of a single polar flagellum.

oxidase-positive,

grow well in alkaline media (pH 9 to 9.6),

VIBRIONACEAE

motile by means of polar flagella

growing on simple media

often grow in and contaminate water supplies, such as whirlpool baths if chlorination is inadequate.

oxidase-positive and are obligate aerobes

capable of growing by anaerobic respiration if nitrate is available

Some strains are mucoid because of abundant production of a polysaccharide capsule and some produce water-soluble pigments.

PSEUDOMONAS

produces two water-soluble pigments:

Pyocyanin, a bluish-green pigment, and fluorescin, a fluorescent greenish-yellow pigment

"grape-like" aroma.

opportunistic pathogen

commonly resistant to multiple antibiotics.

include septicemia, endocarditis, pulmonary infections, ear infections, burn wound infections, urinary tract infections, gastroenteritis, eye infections, and musculoskeletal infections.

Pseudomonas aeruginosa

fever and scant bloody diarrhea with mucus and pus, although in the

early stages of disease voluminous watery diarrhea is seen in many patients

does not invade beyond the mucosa to reach the lamina propria and the mesenteric lymph nodes and

does not lead to bacteremia.

antibiotics shortens the duration of symptoms and shedding

replacement of fluid and electrolytes.

Only rarely does a chronic carrier state occur.

 Invasiveness is the primary virulence factor,

has enterotoxic, cytotoxic, and neurotoxic activities, and is

nearly identical to the verotoxin produced by EHEC strains of E. coli

formation of actin "comets", similar to the mechanism used by Listeria

Type III secretion system and uses the "trigger"-type mechanism to invade target cells.

contains a large (220 kb) virulence plasmid which carries the genes for these virulence factors.

S. sonnei accounts for between 60 and 80 percent of the cases 

remaining cases are mostly caused by S. flexneri.

fails to ferment mannitol,

Shigella dysenteriae

 ferment lactose very slowly

S. sonnei

high fever and abdominal symptoms.

typhoid fever, caused by S. typhi

infection is by the fecal-oral route and bacteria are shed in stool at some stages of disease.

invasion phase of infection patients may be constipated.

systemic infection with organisms present in blood (although not at high titer), and several internal organs.

Humans are the only hosts for S. typhi and S. paratyphi

Septicemia

Organisms are present at large numbers in the blood, usually without concurrent involvement of the gastrointestinal tract

S. choleraesuis and S. dublin

most common kind of Salmonella infection

gastrointestinal tract

nausea, vomiting, and diarrhea as the initial presenting symptoms.

Fever and abdominal cramping are common.

Gastroenteritis (now often called enterocolitis)

caused by Salmonella enteriditis

cause genital tract infections, eye and respiratory infections. 

Chlamydia trachomatis

causes psittacosis.

Chlamydia psittaci

obligate intracellular pathogen.

grow only inside the cell.

rigid cell wall but do not have peptidoglycan layer

cell wall resembles gram negative bacteria but lacks muramic acid.

replicative cycle that is different from other bacteria

divides by complex mechanisms involving elementary and reticuloid body. 

inclusions bodies are useful in the diagnosis

Chlamydia

inclusions bodies are useful in the diagnosis

Chlamydia

cause trachoma

C. trachomatis A, B, and C

clamydia serotype that causes sexually transmitted diseases

trachomatis D-K 

cause lymphogranuloma venerium, lesions on genitalia and infection and inflammation in lymph nodes.

C. trachomatis L1-L3

chlamydia that forms glycogen inclusions

trachomatis

drug of choice for C. trachomatis infection

azithromycin

The drug of choice for C. pneumoniae and C. psittaci and lymphogranuloma venereum

 tetracyclines such as doxycycline

Rocky mountain fever is caused by

Rickettsia ricketsii

Q fever is caused by

Coxiella burnetti

reservoir includes dogs.

the circulation and infect the endothelial cells

causing redness, swelling and edema on the hand and legs and spreads to the trunk.

disease advances the symptoms will include coma and dilerium. 

intravascular coagulation and vascular collapse. 

Rocky mountain fever: This is caused by Rickettsia rickettsii.

disease which is not transmitted by insects bite.

can cause both upper and lower respiratory-track infections.

symptoms include fever, cough, head ache and myalgia.

Pneumonia along with hepatitis is an indication

endocarditis.

Q fever is caused by Coxiella burnetti

maintained inside human louse Pediculus

no animal reservoirs

lesions first appear in the trunk and spread to the hand and legs.

Face, palm and soles are spared.

may experience delirium and coma. In

untreated cases there will be vascular collapse

ELISA and indirect immunofluorescence are two commonly used serological tests that are used for diagnosis.

Epidemic Typhus: The causative agent is R. prowazekii

treatment for all rickettsial diseases

tetracycline along with chloramphenicol

express proteins that cross-react the proteins OX strains of Proteus vulgaris.

This cross reactivity forms a basis of Weil-Felix test. 

R. ricketsii, R. tsutusagamushi and R. perowazekki

large group of heterogeneous bacteria with

unusual morphology (spiral-shaped, long, very slender, flexible) and

Motility (wiggling, corkscrew-like).

difficult to stain

do not grow in vitro. 

Spirochetes

cause of syphilis

Treponema pallidum

cause non-venereal, chronic skin lesions -

primarily in the tropics. 

false-positive serological reactions for syphilis.

Treponema pertenue (yaws)

and

Treponema carateum (pinta) 

cause of louse-borne relapsing fever.

repeated cycles of rise and fall in fever due to changes in the antigenic structure of the organisms

Borrelia recurrenti

most frequent tick-borne disease in the US

skin lesions and arthritis.

Transmitted to humans by hard-bodied ticks

skin lesion begins to develop at the site of the tick bite can become quite large, with a red flat border and central clearing called erythema chronicum migrans,

"flu-like" symptoms also occur in early disease, lasting about one month. If left untreated, the infection will progress to late manifestations in a high percentage of patients. These include neurologic and cardiac symptoms, and, even later, arthralgias and arthritis.

Serologic testing provides confirmation of a clinical diagnosis 

Borrelia burgdorferi is the cause of Lyme disease

oral infection characterized by painful inflammation and necrosis of the gingiva.

"fusospirochetal complex". 

Gram stain is useful in laboratory diagnosis.

Stress, anxiety, and neglect of oral hygiene  may contribute to the etiology

can be treated with antibiotic therapy and improved oral hygiene.

Borrelia vincentii 

acute necrotizing ulcerative gingivitis (ANUG).

antibiotic effective against most spirochetes.

Penicillin

 a systemic disease travels through the lymphatics

first sign of infection is a papule,

turns into an painless, ulcerate 

Secondary stage: fever, sore throat, headache, generalized lymphadenopathy, and prominent mucocutaneous lesions macular rash over the trunk and limbs coalesced masses called condylomata lata. highly infectious.

Latent stage: Absence of signs and symptoms of disease, positive serology. Not infectious.

Late (tertiary) stage gummas, relatively quiescent granulomatous lesions of the dermal elements or supporting structures of the body.d hard chancre highly infectious.

Treponema pallidum - Syphilis

animal disease transmitted accidentally to humans.

slender, very tightly coiled hook at one or both ends only two axial filaments.

can be cultured on ordinary lab media obligate aerobes.

Antibiotic treatment is effective in early stages of disease. If there is no jaundice, no mortality

jaundice, mortality is10 to 40%. .

pathogenic to humans: pomona (pig), canicola (dog), and icterohaemorrhagiae (rat).

contact with urine from a wide range of infected animals contaminated water.

Occupational disease

Signs and symptoms include chills and fever, headache, photophobia (conjunctival infection), gastrointestinal disturbances, muscle pain. The occurrence of hemorrhage, jaundice    (icterus), and azotemia indicate a poor prognosis.

Leptospira - Leptospirosis