Gram-Negative Bacteria Flashcards

Question

*Yersinia* spp.

Answer 1

* Yersinia enterocolitica* causes infectious diarrhea * Y. pestis* causes plague

Answer 2

cuase of plague ("The Black Death") infection acquired in three ways: 1) transmission from rats/fleas (bubonic plague) 2) human-to-human transmission by aerosols (pneumonic plague) 3) direct contact with infected animal tissues (primary septicemic plague) endemic cases still occur in the US (about 15 cases/year) usually hikers or hunters who acquire the illness from wild animals 90% of US cases occur in NM, AR, CO, and CA

Answer 3

hms locus (hemin storage locus) - bacterial colonization of flea foregut multiplies in flea foregut, blocks passage of blood meals, leads to regurgitation of blood meal along with bacteria bacteria inoculated into host and travel to nearest lymph node bacteria multiply and form bubos, leak into blood stream and releases LPS and causes septic shock and DIC eventually, make their way to macrophages in the lungs spread of disease to close contacts by aerosols adhesins - Ail, chromosomally encoded, type III secretion system (on plasmid) - secretes several Yops (Yersinia outer proteins) - YopE and YopH Fra1 - antiphagocytic protein that forms part of a capsule around *Y. pestis* Pla - plasminogen activator -\> cleaves fibrin clots -\> dissemination

Answer 4

chromosomally encoded adhesin *Yersinia pestis*

Answer 5

antiphagocytic protein that forms part of a capsule *Yersinia pestis*

Answer 6

plasminogen activator -\> cleaves fibrin clots -\> dissemination *Yersinia pestis*

Answer 7

bubonic plague pneumonic plague primary septicemic plague

Answer 8

2-6 day incubation period, bubo develops near site of flea bite fevers, chills, myalgias, arthralgias, and headache bubo becomes progressively enlarged, painful, and arythematous sepsis and death *Yersinia pestis*

Answer 9

1-4 day incubation period sudden onset of chills, fever, headache, myalgias, and weakness productive cough (sometimes bloody) and dyspnea particularly severe and associated with high mortality rates may result in aerosol spread of the organism from person to person Yersinia pestis

Answer 10

follows direct inoculation of the organism into the bloodstream nausea, vomiting, diarrhea, and abdominal pain diagnosis often not made until late in the course of the illness *Yersinia pestis*

Answer 11

blood cultures bubo aspirates for bobnic plague sputum samples for pneumonic plague grows on commonly used laboratory media such as sheep blood agar Giemsa stain - characteristic bipolar appearance - "closed safety pins"

Answer 12

streptomycin or gentamicin tetracycline/doxycycline or chloramphenicol are alternatives

Answer 13

avoidance of sick or dead animals in endemic areas antibiotic prophylaxis for direct contact with pneumonic plague tetracycline, doxycycline, and trimethoprim-sulfamethoxazole whole-cell vaccine unclear efficacy not routinely recommended

Answer 14

* Pseudomonas aeruginosa* * Legionella pneumophila* * Vibrio cholerae* * Heliobacter pylori* * Campylobacter jejuni*

Answer 15

aerobic Gram-negative rods use a broad variety of organic compounds for growth inhabit many different environments such as soil, water, and man-made solutions *Pseudomonas aeruginosa* is the most medically important

Answer 16

found in most environments including faucets and drains in hospitals capable of using many different organic compounds for growth

Answer 17

Pili - adherence Exotoxin A - similar to diphtheria toxin -\> ADP ribosylates EF-2 Alginate LasA and LasB proteases that act together to degrade elastin type III secretion system - kill cells and distrupt action cytoskeleton quorum-sensing - system by which bacteria determine their numbers endotoxin

Answer 18

acts similarly to diptheria toxin -\> ADP-ribosylates EF-2 *Pseudomonas aeruginosa*

Answer 19

exopolysacharide, "mucoidy" phenotype in CF patients antiphagocytic *Pseudomonas aeruginosa*

Answer 20

proteases that act together to degrade elastin *alginate*

Answer 21

system by which bacteria determine their numbers *Pseudomonas aeruginosa*

Answer 22

opportunistic pathogen colonizes the majority of adult cystic fibrosis patients - impossible to clear from cystic fibrosis lungs once established leads to repeated bouts of respiratory exacerbations nosocomial infections - pneumonia (ventillated patients and necrotizing) and urinary tract infections, wound infections bacteremia and sepsis in cancer patietns with decreased numbers of neutrophils in their blood characteristic skin lesions are called ecthyma gangrenosum hot tub folliculitis

Answer 23

grows on many types of laboratory media produces a grape-like odor produce fluorescent pigments oxidase positive

Answer 24

intrinsic and acquired resistance to multiple antibiotics serious infections should be treated with two drugs at least until susceptibilities are known aminoglycosides, piperacillin, ceftazidime, imipenem, aztreonam, fluoroquionolones most other penicillins and cephalosporins are not active against this bacteria

Answer 25

tap water should not be used to wash respiratory equipment has been found contaminating many different hospital sites and solutions, including some disinfectants

Answer 26

thin Gram-negative rods *L.pneumophila* - most medically significant 17 other species of Legionella have been associated with human disease

Answer 27

aerobic Gram-negative bacilli cause of Leionarre's Disease inhabits natural bodies of water as well as cooling towards and water distribution systems, where they parasitize amoebae greater than 10 serogroups - serogroup 1 causes 80% of disease

Answer 28

facultative intracellular pathogen primarily infects macrophages attaches to macrophages and provokes a novel form of phagocytic uptake called "coiling phagocytosis" entails the formation of a long, thin pseudopod by the macrophage wraps around the bacterium engulfs it in a coiled vesicle fusion of vesicle (phagosome) with lysosomes is blocked, and ER membranes with ribosomes are recruited to the phagosome baceria survive and multiply in the phagosome and eventually lyse macrophage and infects the new cells dot locus phospholipase C

Answer 29

necessary for the blockage of phagolysosome fusion and ribosome recruitment encodes a type IV secretion system - another delivery system by which bacteria inject toxins directly into host cells *Legionella pneumophila*

Answer 30

hydrolyzes phosphatidyl choline in eukaryotic membranes *Legionella pneumophila*

Answer 31

airconditioning cooling towers and water faucets are the primary source of organism in human infection infection can occur by aspiration of water or inhalation of aerosol - vegetable mister in the produce department of a supermarket no-human-to-human transmission nosocomial outbreaks are important, but community-acquired disease also occurs causes a pneumonia that is often severe - fever exceeding 40.5 degrees C occurs in 20% of patients respiratory symptoms accompanied by - headach, changes in mental status, nausea, vomiting, diarrhea, hyponatremia

Answer 32

poorly stained by Gram's method visualized by using Dieterle silver staining grows on buffered charcoal-yeast aextract (BYCE) agar, which contains L-cysteine, a required amino acid antibiotics are used to suppress growth of other bacteria in respiratory samples direct fluorescent antibody test (nto very sensitive) urinary antigen test (sensitive and specific but only serogroup 1)

Answer 33

macrolides and ciprofloxacin rifampin is added iun severe disease

Answer 34

disinfection of hospital water systems may be helpful in preventing nosocomial cases

Answer 35

commonly live in salt water and freshwater often cuase infections associated with exposure to seawater * Vibrio cholerae* comma-shaped rod that causes cholera, a severe form of diarrhea * V. vulnificus* causes gastroenteritis, causes wound infections following cuts that are exposed to seawater, may also cause life-threatening bacteremia, especially in individuals with liver disease or iron-overload states

Answer 36

Gram-negative, slender, spiral-shaped organisms *Helicobacter pylori* is responsible for most human infections, though other species cause similar infections in animals

Answer 37

grows best under microaerophilic conditions common cause of peptic ulcer disease

Answer 38

grows in mucus that overlies gastric mucosa urease flagella and curved shape allows motility through mucus that lines the stomach, adherence to gastric epithelial cells VacA Type IV secretion

Answer 39

splits ammonia from urea -\> alkaline microenvironment -\> allows organism to survive the acid conditions of the stomach *Helicobacter pylori*

Answer 40

cytotoxin, causes vacuolation of cultured epithelial cells patients with ulcers are more likely to be infected with isolates that have detectable VacA activity *Helicobacter pylori*

Answer 41

stimulates inflammation *Helicobacter pylori*

Answer 42

approximately 30% of peopl in the US are infected, usually asymptomatic, gastric inflammation is nearly always present major cause of peptic ulcer disease risk factor for adenocarcinoma, non-Hodgkin's lymphoma, and low-grade B cell mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach approximately half of the cases of MALT lymphomas regress upon antibiotic treatment

Answer 43

endoscopy -\> histologic examination of tissue biopsy giemsa or silver stains are used to visualize the organisms, though culturing *H. pylori* is difficult urease test: biopsy specimens are assayed for urease activity urea breath tests - patient drinks a radio-labeled urea solution and look for exhalation of radio-labeled CO2 serological tests for igG are simple and sensitive, levels do not decrease for six months after following usccessful antibiotic therapy antibody tests detect bacterial antigens in stool

Answer 44

treatment requires multiple drugs two popular regimens: proton-pump inhibitor + clarithromyin + amoxicillin protin-pump inhibitor + amoxicillin + metronidazole

Answer 45

no vaccine currently available

Answer 46

curved Gram-negative rod frequent cause of gastroenteritis leading to diarrhea

Answer 47

small Gram-negative cocobacilli facultative anaerobe H. influenzae - otitis media, sinusitis, bronchitis, epiglottitis, pneumonia, meningitis sexually transmitted disease similar to syphilis

Answer 48

tiny, gram-negaive coccobacilli strict anaerobes cause of Whooping Cough

Answer 49

Pili, filamentous hemagglutinin (FHA), pertactin - allows adherence to ciliated epithelial cells in the upper airway, FHA mediates adherence to epithelial cells by binding to galactose residues and to PMNs by binding CR3 pertussis toxin adenylate cyclase, makes cAMP in the prosence of host cell calmodulin - inhibits leucocyte function capsule - only encapsulated organisms are virulent endotoxin

Answer 50

A-B toxin that exists as a hexamer with subunits S1-S5 S2 through S4 mediate toxin adherence to host S1 has enzymatic activity, ADP-ribosylates a host cell G protein, which ultimately causes a rise in cAMP levels S5 acts as a scaffold to position other subunits action of toxin increases number of CR3 molecules on the cell surface, which increases FHA binding and bacterial internalization, bacteria survive inside phagocytes also blocks recruitment of neutrophils

Answer 51

Whooping cough highly communicable transmission by droplets infects upper airway 1) incubation 2) Catarrhal stage - mild coughing and sneezing, patient very infectious 3) paroxysmal stage - explosive cough followed by "whoop" during inhalation, leads to exhaustion, cyanosis, vomiting, and convulsions, resolution very slow

Answer 52

samples collected from the nasopharynx grown on Bordet-Gengou medium or charcoal-containing medium after 4 weeks of symptoms, cultures are rarely positive new PCR test

Answer 53

antibiotic treatment after onset of paroxysmal stage and is not as effective in altering clinical course macrolides are the treatment of choice TMP/SMX is an alternative

Answer 54

whole-cell kileld vaccine - given with tetanus and diphtheria toxoid vaccines (DTP) immunity wanes after 2 years - no protection is present after 12 years concern over CNS side-effects increased incidence of side-effects in adults - not to be given after childhood acellular vaccines - also given with tetanus and diphtheria toxoid vaccines (DTaP) detoxified pertussis toxin, FHA, pertactin, pili to generate protection against pertussis associated with fewer side-effects currently licensed for children formulation with reduced concentrations licensed for adolescents and adults

Answer 55

*Brucella abortus, B. melitensis, and B. suis* small, coccobacillary, aerobic, Gram-negative bacteria cause disease in humans as well as cattle, goats, and hogs acquire infection through contact with mucous membranes, cuts, inhalation, consumption of unpasteurized milk or other diary products veterinarians, meat inspectors at particular risk able to survive inside macrophages

Answer 56

fever, chills, malaise, and drenching sweats symptoms last for weeks or months **diagnosis** - isolation of the organism from the blood or biopsy specimens, serological tests treatment - doxycycline + (rifampin or gentamicin or streptomycin) prevention - animal vaccine but no human vaccine zoonotic infection

Answer 57

causes tularemia small, metabolitcally facultative, Gram-negative coccobacillus similar in morphology to *Brucella* infects rabbits, squirrels, muskrats, beavers, and deer human infection follows contact with inty breaks in the skin, exposure to mucous membranes, ingestion, inhalation, or tick bite **pathogenesis** - multiplies within macrophages

Answer 58

site of inoculation often becomes ulcerated regional lymphadenopathy fevers and chills pneumonia and dissemination to multiple organs difficult to grow, requires special media serological assay is available

Answer 59

*Pasteurella multocida* is a small gram-negative coccobacillus part of normal mouth and respiratory flora of some animals (cats and dogs) humans usually become infected from a cat or dog bite

Answer 60

Gram-negative diplococci neisseria meningitidis - meningitis and sepsis *N. gonorrhoeae* - STD

Answer 61

morphologically and metabolically resembles Neisseria spp. at one time was classified int he genus *Neisseria* small, Gram-negative cocci or coccobacilli causes otitis media, sinusitis, bronchitis, and pneumonia

Answer 62

many are members of the normal flora of the GI tract, respiratory tract, and female genital tract opportunistic pathogens common anaerobic Gram-negative rods include *Bacteriodes* spp, *Prevotella* spp., and *Fusobacterium* spp.

Gram-Negative Bacteria Flashcards

(86 cards)