Enterobacteriaceae Flashcards

Question

Enteroaggregative E. Coli (EaggEC) infection | Symptoms

Answer 1

Persistent watery diarrhea, low grade fever, vomiting, dehydration if no fluid replacement

Answer 2

Bacteria adhere to discrete areas and clump “like stacked bricks” Release shigella-like toxin called EAST (entero aggregating stable toxin)0 causes mucosal cells to swell and RBC to coagulate in intestinal capillaries

Answer 3

Treat the same as for ETEC and EIEC

Answer 4

Cattle are primary reservoir, as well as contaminated produce in US 4 days post exposure: watery diarrhea and cramps. Then 40% develop copious bloody diarrhea and even worse cramping. Usually no fever 10% develop hemolytic uremic syndrome w/ acute renal failure

Answer 5

After attaching, secrete verotoxin 1 and 2 - verotoxin 1: just like shigella toxin. Inhibits protein synthesis and results in cell death - verotoxin 2: structurally different but functionally the same

Answer 6

Same as ETEC, EIEC and EaggEC, but fluoroquinolones (siprofloxin) can worsen the disease by activating phage. Bacteriophage can integrate into host chromosome (will kill cells)

Answer 7

Caused by EHEC. Blood vessels in epithelium of glomeruli damaged by toxin. Causes kidney failure and platelet lysis (thrombocytopenia) Treatments can include transfusions and dialysis Lethal in 5-10%, neurological deficits in 5-10%

Answer 8

Recurrent bladder infections due to pod-like formations protecting bacterial colonies in bladder epithelial cells. Can lead to acute cystitis (bladder infection) and pyelonephritis (kidney infection)

Answer 9

Opportunistic capsule-protected bacteria One of the leading causes of drug resistant nosocomial infections (Causes pneumonia, as well as bacteremia, meningitis, wound infections, and UTI’s)

Answer 10

Ubiquitous soil/ plant bacteria, as well as digestive tracts of animals and humans Can contaminated dairy products (opportunistic infectsions) *Causes opportunistic nosocomial infections in immunocompromised patients* Almost never see community acquired infections of this strain

Answer 11

Facultative anaerobe Proteus mirabilis most commonly seen in human disease Highly motile with tendency to swarm. Urinary tract infections in those with catheters and other indwelling units Resistant to many antimicrobial drugs

Answer 12

Overt pathogens Produces type 3 secretion systems (hypodermic meddle type protein insertion into host cell) Proteins inhibit phagocytosis, rearrange cytoskeleton (cell to cell motility) and induce apoptosis

Answer 13

Resistant to bile salts and produce H2S! Motile gram negative facultative anaerobes DO NOT ferment lactose

Answer 14

Animals main reservoir Ingestion of contaminated food (eggs and poultry) Fecal-oral route (especially in children) Disease of consumption

Answer 15

``` Generic= salmonellosis Enteritis= acute gastroenteritis Enteric fever= severe form is typhoid fever Septicemia Asymptomatic carriage ```

Answer 16

Most common form of salmonellosis High infectious dose 6-48hr incubation period Nausea, vomiting, non-bloody diarrhea, fever, cramps, myalgia (tiredness), headache common

Answer 17

Due to invasive ness, intracellular survival and multiplication in macrophages, and endotoxin lipid A

Answer 18

1. Penetrate mucus, 2. Internalized into GI M-cells, and multiply 3. PMN’s take up, to confine infection to GI, but travel in macrophages to other areas 4. Inflammatory response (and cAMP) causes diarrheal symptoms

Answer 19

Slightly lower infectious dose (10^6 vs 10^8) 10-14 day incubation period. Show signs signs of sepsis w/ week+ long fever BEFORE abdominal symptoms come in. Fever break and build nearly every day, climbing up to a peak of 104-105ºF Colonize in liver, spleen and BONE MARROW as mode of sepsis Lipid A cause of fever (pyrogenic)

Answer 20

Chronic carriage in 1-5% of cases—> shedding of bacteria in feces up to 20 weeks after symptoms clear up. Gall bladder main reservoir. Chronic carriage very very rare (<<1% of cases)

Answer 21

Enteritis: supportive care (antibiotics not recommended) Enteric fever: antibiotics, mostly to avoid carrier state Vaccination can reduce risk of disease for travelers to endemic areas

Answer 22

Shigella Sonnei: most common in industrial world Shigella flexneri: most common in developing world Shigella boydiii Shigella dysenteriae: greatest clinical impact/ most dangerous

Answer 23

``` Non-lactose fermenting Gram-negative facultative anaerobe Resistant to bile salts Low infectious dose (10-100 organisms!) Humans only reservoir ```

Answer 24

Person to person, fecal-oral route At-risk people: children, daycares, nurseries; male homosexuals; Incubation period: 1-3 days

Answer 25

``` Watery diarrhea (can develop into dysentery) Leading cause of infant diarrhea and mortality due to rapid dehydration. Inflammation of intestines (especially colon) with severe abdominal cramps, straining to defecate (tenesmus) and low-volume stools containing blood, mucus, and fecal leukocytes ```

Answer 26

1. Shigella attaches to M cell. Endocytosis 2. Bacteria lyses phagosome and replicates in the cell 3. Develops actin tails to move cell to cell- cell to cell engulfment 4. Causes apoptosis of PMN’s to reinfect 5. Loss of epithelial cells destroys the integrity of the mucosal surface 6. Red blood cells leak into the lumen, resulting in bloody diarrhea

Answer 27

-Invasiveness: attachment and internalization, and a large virulence plasmid -Exotoxins: enterotoxin, neurotoxin, and cytotoxin AB type toxin (binding and action) Similar to shiga-like toxin encoded by lysogenic bacteriophage

Answer 28

Gram negative

Answer 29

Facultative anaerobe

Answer 30

Oxidase negative

Answer 31

``` Yersinia pestis (plague) Yersinia enterocolitica (enteropathogenic) Yersinia pseudotuberculosis (enteropathogenic) ```

Answer 32

Ingestion of contaminated food

Answer 33

Rodents and domestic animals

Answer 34

Yersinia enterocolitica commonly causes a disease in humans, Yersinia pseudotuberculosis commonly is a disease of other animals

Answer 35

Both cause fever and abdominal pain, but ENTEROCOLITICA causes bloody diarrhea

Answer 36

Bacteria invade the intestinal epithelium by invasion of M cells. They are then released at the basal surface, where they can invade the underlying lymphoid tissue (multiplying both inside and outside host cells)

Answer 37

Side agglutination to identify cultures with specific antibodies based on the “O”-antigen

Answer 38

Mild-diarrheal disease is self-limiting and can often be treated at home with the help of fluids. For severe cases (meningitis/ sepsis) antibiotic treatment should be started as soon as possible (rosephrin and streptomycin)

Answer 39

No preventative measures available beyond general hygiene

Answer 40

Tiny, gram-negative bacilli (unusual bipolar staining)

Answer 41

1. Capsule and envelope proteins (protect against phagocytosis and foster intracellular growth) 2. Coagulase- clots plasma 3. Endotoxin- responsible for many of the damaging symptoms 4. Murine toxin- causes edema and necrosis in mice and rats (has not been shown to play a role in human disease)

Answer 42

Zoonotic infection- humans accidental hosts | Very very contagious and with a very short treatment window

Answer 43

Sylvatic (wild) plague Urban (domestic) cycle of plague Human cycle of plague

Answer 44

Wild rodents serve as the reservoir (prairie dogs, mice, rabbits etc.) with a wild rodent flea as the vector

Answer 45

Reservoir: domestic (urban) black rat Vector: oriental rat flea (xenopsylla Cheopis)

Answer 46

Bubonic plague acquired from contact with either sylvatic or urban reservoirs (or arthropod vector bite) - then further transmitted in human populations via airborne droplets to spread pneumonic plague

Answer 47

Swollen, painful lymph nodes, fever, septic shock in later stages (transmission= from vector to host through bite)

Answer 48

Host-to-host transmission via inhaled bacterial material (cough) Flu-like illness progressing to mucous, bloody sputum, dyspnea, cyanosis and is rapidly fatal

Answer 49

- Very low infectious dose- travel in blood to nearest lymph node, where are taken up by macrophages. -Then lymph nodes (especially arm-pit and groin) swell as bacteria proliferate and stimulate inflammatory response. - lysis of the bacteria leads to LPS release, causing septic shock. This toxin causes DIC (blood clots in capillaries and systemic bruising- hence Black Death)

Answer 50

Infection localized to the lungs, highly contagious, toxin permeates rapidly and is almost always fatal without treatment. Bacteria grows within macrophages.

Answer 51

Streptomycin, tetracycline, or chloramphenicol (and quarantine) Vaccine not widely available but exists, and given in rare occasions