Bacteria – Microbiology – Flashcards
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associated with gastritis, duodenitis, and peptic and duodenal ulcers.
Gram-negative, highly motile, oxidase-positive, strongly curved bacterium.
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.
may be S-shaped, gull-winged, or comma-shaped.
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
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.
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.
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
similar to Enterobacteriaceae
facultative Gram-negative curved rods motile by means of a single polar flagellum.
grow well in alkaline media (pH 9 to 9.6),
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.
produces two water-soluble pigments:
Pyocyanin, a bluish-green pigment, and fluorescin, a fluorescent greenish-yellow pigment
commonly resistant to multiple antibiotics.
include septicemia, endocarditis, pulmonary infections, ear infections, burn wound infections, urinary tract infections, gastroenteritis, eye infections, and musculoskeletal infections.
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,
ferment lactose very slowly
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
Paratyphoid fever is
caused by S. paratyphi A, S. schottmueller
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
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.
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
inclusions bodies are useful in the diagnosis
C. trachomatis A, B, and C
clamydia serotype that causes sexually transmitted diseases
cause lymphogranuloma venerium, lesions on genitalia and infection and inflammation in lymph nodes.
C. trachomatis L1-L3
chlamydia that forms glycogen inclusions
drug of choice for C. trachomatis infection
The drug of choice for C. pneumoniae and C. psittaci and lymphogranuloma venereum
tetracyclines such as doxycycline
Rocky mountain fever is caused by
Q fever is caused by
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
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.
cause of syphilis
cause non-venereal, chronic skin lesions -
primarily in the tropics.
false-positive serological reactions for syphilis.
Treponema pertenue (yaws)
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
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.
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.
acute necrotizing ulcerative gingivitis (ANUG).
antibiotic effective against most spirochetes.
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.
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