L15- GI Infections VI (inflam. diarrhea, bacteria) Flashcards
list the types of Salmonella, associated species, and what they cause
Typhoidal:
- typhoid / paratyphoid fever
- S. typhi, S. paratyphi A/B/C
Non-Typhoidal:
- gastroenteritis / food poisoning
- other Salmonellas
list the three important Salmonella microbial features
- Gram(-) rods
- motile
- non-lactose fermenter
Salmonella spp. typing depends on….
- O Ag, cell wall
- H Ag, flagella
- Capsular Vi (virulence) Ag
Salmonella has (1) property, therefore it needs (high/low) inoculation dose
1- acid labile
2- large dose (many destroyed in stomach)
Typhoid Salmonella reservoir is (1), mainly transmitted via (2)
Non-typhoid reservoir is (3), mainly transmitted via (4)
1- humans
2- person-to-person transmission
3- humans + animals
4- contaminated foods (poultry, dairy)- note person-to-person is less common
list the clinical manifestations of Salmonellosis and indicate the associated species
Gastroenteritis: S. typhimurium, S. enteritidis, S. newport
Septicemia / Bacteremia: (rare) S. cholerasuis
Enteric / Typhoid Fever: S. Typhi
list the complications of Salmonellosis
-CVS, CNS, pulmonary, hepatobilliary involvement
- reactive arthritis
- osteomyelitis
Salmonellosis –> gastroenteritis:
- (1) species
- (2) main infection description
- worse effects in (3) patients and invasive in (4) patients
- (5) is a common associated symptom
1- S. typhimurium, S. enteritidis, S. newport 2- self-limiting diarrhea 3- young, elderly 4- children, cancer, SCD Pts 5- vomiting
Salmonellosis –> septicemia:
- (1) species / transmission
- defining condition in (2) patients
- (3) clinical presentation
1- any species found in contaminated food / water
2- AIDS
3- fever/chills, oliguria, tachycardia, tachypnea, vomiting, diarrhea
list the risk factors for Salmonella Septicemia (in order of most importance)
1a) age extremes, immunosuppression, malignancy, congenital immune defects
1b) other predisposing co-morbidities (includes liver disease, hemoglobinopathies)
2) alteration to GIT by suppression of gastric acid (antacids) or antibiotics
Salmonella pathogenesis:
- (1) route of entry
- (2) mediates attachment
- (3) and (4) aid in intracellular survival, where they are contained in (5)
(similar to Shigella, although replication in vacuoles, not cytoplasm)
1- paracellularly, M-cell endocytosis
2- SPI-1 (salmonella pathogenicity Island-1)
3- SPI-2
4- T3SS (type 3 secretion system)
5- SCV (salmonella containing vacuoles)
describe Salmonella pathogenesis (gastroenteritis)
1) ingestion
2) attaches to SI
3) invades M cells (Peyer’s patches) + enterocytes (PAI encoded)
4) survive/replicate w/in vacuole (PAI encoded)
5) transports across cytoplasm
6) release into blood/lymph
Enteric fever:
- (1) organisms/spp.
- (2) reservoir
- (3) geographic areas
(Typhoid / Paratyphoid fever)
1- S. typhi, S. paratyphi A/B
2- humans (no animals)
3- Asia, Mexico, India (travelers to those places)
describe Salmonella pathogenesis (Typhoid/Paratyphoid fever)
1) blood stream
2) macrophage involvement
3) transports to liver, spleen, bone marrow
4) colonization in gall bladder
5) second bacteremia
6) replication in bile
7) re-enters intestines
Enteric Fever:
-(1) is required and (2) is occasionally seen before diagnostic testing
-(3) and (4) are used in diagnostic testing
1- h/o travel to endemic areas
2- transient macular rash (rose-colored) on trunk
3- examination of blood: anemia, leukopenia, absence of eosinophils
4- blood culture –> S. typhi isolation (needs many samples)
2-5% of typhoid patients exhibit _______, a very dangerous property
- continued fecal excretion
- asymptomatic carrier state that allows for transmission
Salmonella Enterocolitis:
- (1) incubation
- (abrupt/insidious) onset
- (3) fever description
- (4) duration
- (5) GI Sxs
- (6) blood cultures
- (7) stool cultures
1- 8-48hrs 2- abrupt 3- low grade fever 4- 2-5 days 5- n/v/d 6- negative 7- positive soon after onset
Salmonella Septicemia:
- (1) incubation
- (abrupt/insidious) onset
- (3) fever description
- (4) duration
- (5) GI Sxs
- (6) blood cultures
- (7) stool cultures
1- variable 2- abrupt 3- rapid rise and spiking septic fever 4- variable 5- none 6- positive 7- infrequently positive
Salmonella Enteric Fever:
- (1) incubation
- (abrupt/insidious) onset
- (3) fever description
- (4) duration
- (5) GI Sxs
- (6) blood cultures
- (7) stool cultures
1- 7-20 days
2- insidious
3- gradual, high plateau, typhoidal state
4- several wks
5- early constipation, bloody diarrhea
6- positive in 1st/2nd wk
7- positive after 2nd wk (negative early on)
Salmonella:
- (1) appearance on initial agar
- (2) appearance on (3) / secondary agar
- (3) is another agar
- (4) are the three key microbial features
1- pale/colorless on MacConkey agar 2- black colonies (H2S production) 3- S-S agar (Salmonella-Shigella agar) 4- EMB (eosin methylene blue agar) 5- motile, Gram(-) rod, non-lactose fermenter
Campylobacter spp. microbial features
- small, curved spiral rods, 1.5-3.5mm x 0.2-0.4mm
- Gram(-), motile (single falgellum), oxidase(+)
- microaerophilic
- selective growth at 42-43C (none at 25C)
Campylobacter spp. are common infections in (1) countries, mainly the (2) species. (3) list the reservoirs / routes of transmission.
1- N. America, Europe, Australia
2- C. jejuni
3- GIT of large domestic animals: raised poultry, cows, sheep, pigs, cats, dogs
(rarely person-to-person, fecal-oral)
Campylobacter pathogenesis:
- ingest (1) amount of pathogen
- invasion of (2) segment mucosal surface
- (3) production initiated in GIT
1- 500-10000 organisms (low inoculation dose)
2- SI, LI
3- Endotoxin, Enterotoxin (watery diarrhea), Cytotoxin (bloody diarrhea)
list the clinical features / symptoms of Campylobacter spp. infections (GIT)
(similar to Shigella, Salmonella)
- slight vomiting, profuse diarrhea (blood stained), severe abdominal pain
- severe prostration (getting on all fours in pain)
- pyrexia (fever)
list the common complications of Salmonellosis
1) (40%) Acute inflammatory demyelinating polyneuropathy / Guillain-Barre Syndrome
2) (1%) reactive arthritis, mostly knee joint for 6-12 mos
C. jejuni diagnosis:
- cultured from (1) samples
- has (2) appearance on (3) special culture
- (4) positive on biochemical analysis
- similar microscopic appearance to (5)
1- fecal specimen 2- grey, mucoid, (spreading) 3- Skirrow agar 4- oxidase(+), catalase(+) 5- Vibrio spp., Gram(-)
Of the Yersinia spp., (1) causes the most GIT infections, mainly in (2) population. (3) is another species with less frequent infections. These Yersinia spp. prefers (4) climates- include geographic areas.
1- Y. enerocolytica
2- children 1-7y/o (more in <4y/o, or adults at daycare center)
3- Y. pseudotuberbulosis
4- cooler climates: Japan, Canada, Scandinavia
Yersinia spp.:
- (1) reservoirs
- (2) most common route of transmission
- (3) optimal growth temperature
1- aquatic and domestic animals (so many)
2- contaminated food, contact with infected animal/feces
3- -1C - 40C (psychotroph - facultative psychrophile)
Yersinia spp. pathogenesis (GIT infections):
- contains (1) toxin with (2) cellular effect
- Sxs will mimic (3)
1- ST enterotoxin (chromosomal)
2- inc cGMP
3- appendicitis (if it invades ileum = pseudo-appendicitis): abdominal pain, diarrhea, fever, rarely vomiting
Yersinia spp. clinical features (GIT infections):
- described as (1) disease
- (2) incubation period, (3) duration
- (4) Sxs
1- self-limiting enterocolitis
2- 3-7 days
3- 14-21 days (or longer)
4- abdominal pain, diarrhea, fever, rarely vomiting (pseudo-appendicitis)
list the defining microbial features of Yersinia spp. (GIT infections)
- Gram(-), bipolar staining, coccobacilli
- glucose(+), sucrose(+)
- catalase(+), oxidase(+)
Yersinia spp. (GIT infections):
- Dx usually requires (1) sample
- (2) appearance on initial agar, then (3) agar is used
- (4) may also be used to aid Dx
1- stool sample
2- pinpoint colonies on MacConkey (48hrs)
3- specialized Yersinia media
4- Serology
Non-Cholerae Vibrio spp.:
- (1) and (2) are the main species, include main disease cause
- (3) is the main source of infection
- (4) is the main difference from V. cholera
1- V. parahemolyticus --> gastroenteritis 2- V. vulnificus --> wound infection (+ V. alginolyticus) 3- shellfish / seawater 4- encapsulated + able to invade blood
Non-Cholerae Vibrio spp. are considered (1) organisms found in (2) environmental areas and causing (3) in 25% of patients
1- halophilic organisms
2- coastal waters (e.g. Gulf of Mexico)
3- inflammatory diarrhea
V. parahemolyticus
- (1) is main source of infection
- produces (2) virulence factors
- (3) are the clinical Sxs
1- ingestion of raw / poorly cooked seafood (Japan- raw fish, USA- shellfish)
2- enterotoxin (ST), hemolysin
3- watery diarrhea, abdominal cramps, n/v –> bloody diarrhea
V. vulnificus:
- most commonly found in (1) geographic area
- (2) list the three possible resulting infections, include infection source
- highest concern is infection in (3) patients
1- Gulf of Mexico
2:
-Acute gastroenteritis: raw / undercooked shellfish
- Necrotizing wound infection: injured skin + contaminated marine water
- Invasive sepsis: raw / undercooked shellfish (oysters) + immuno-compromised individuals
3- patients with underlying liver disease
Non-cholera Vibrio spp. general pathogenesis and its factors
poorly understood
Virulence Factors:
- capsule
- endotoxin
- flagellum
- metalloprotease, hemolysin, cytolysin, phospholipase (extracellular products)
- Heme receptors, siderophores (Fe acquisition)
- fibronectin binding protein, pili (adherence)
Non-Cholera Vibrio spp.:
- (1) samples screen for (2) activity
- (3) is the main agar with (4) as the differentiating agent- explain
1- stool samples
2- oxidase activity
3- TCBS: thiosulphate-citrate-bile salts-sucrose
4- sucrose:
(+): V. cholera, yellow appearance
(-): V. parahemolyticus, V. vulnificus, normal green (no color change) appearance
