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Micro > Gram (-) Bacteria > Flashcards

Gram (-) Bacteria Flashcards

1
Q

Virulence factor of H. Influenzae

A

Polysaccharide capsule (type B)

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2
Q

H. influenza requires what factors for growth on CAP

A

Factor X [hemin] and V [NAD]

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3
Q

Habitat &reservoir of H. influenzae

A

URT
Human nasopharynx

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4
Q

Pathogenesis of H. influenzae requires which enzymes

A

-Type b [polyribitol phosphate]
-IgA Protease

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5
Q

H. influenzae affects what age group

A

6 months to 1 year

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6
Q

Most common disease caused by H. influenzae
-sign?
-demographics?

A

Epiglottitis
■ Thumb sign
■ Most especially to UNVACCINATED children

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7
Q

Tx for H. influenzae infection

A

Ceftriaxone

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8
Q

Prevention of H. influenzae infection?
-given when?

A

HiB Vaccine containing the type b capsular
polysaccharide conjugated to dipheroid toxoid
○ Given between 2 and 18 months of age

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9
Q

STD, Encapsulated, pleomorphic rods
-causes what disease?

A

-Haemophilus ducreyi
● Chancroid (genital ulcers)

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10
Q

Small gram negative rods, strictly aerobe
-Cultured on?

A

Bordetella pertussis
-Bordet-Gengou Media or Regan-Lowe Charcoal

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11
Q

Habitat & transmission of B. pertussis

A

Upper respiratory tract
-respiratory droplet

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12
Q

Pathogenesis of B. pertussis?

A

○ Filamentous hemagglutinin
■ Mediates attachment

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13
Q

Causes ADP-ribosylation
■ Activates G protein 3
■ Extracytoplasmic [false] adenylate cyclase - moa??

A

Pertussis toxin
-inhibit phagocytosis

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14
Q

Damages ciliated cells → causes whooping
cough

A

Tracheal cytotoxin

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15
Q

➔ It is a very contagious respiratory disease
➔ It is characterized as a severe hacking cough followed by a high pitched sound

A

Whooping Cough

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16
Q

➔ Paroxysmal pattern of hacking coughs accompanied by production of copious amounts of mucus that end with an
inspiratory “whoop”

➔ S/sx
◆ Difficulty of Breathing
◆ Vomiting
◆ Dehydration

➔ Incubation Period: ?

A

Pertussis or Tuspirina
-7-10 days

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17
Q

Phase of pertussis that
○ lasts for 1-2 weeks
○ s/sx: rhinorrhea, malaise, fever, sneezing (contagious), anorexia
○ Mngt: ??

A

Catarrhal stage
-antibiotics

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18
Q

Phase of pertussis that
○ lasts for 2-4 weeks
○ “??” → bursts of non-productive coughs
○ Increased number of ?? in blood smear
○ Note: Antibiotics is ?? during this stage

A

Paroxysmal stage
-whoops
-lymphocytes
-ineffective

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19
Q

Phase of pertussis that
○ lasts for 3 to 4 weeks [or longer]
○ Diminished paroxysmal cough
○ Development of secondary complications
■ ??, Seizure, ??

A

Convalescence stage
-pneumonia, encephalopathy

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20
Q

Treatment for B. pertussis

A

Erythromycin

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21
Q

Prevention of B. pertussis

A

Acellular vaccine in combination with diphtheria and tetanus toxoids [DTaP]

22
Q

Poorly / Weakly gram negative rods
● Facultative intracellular pathogen

● Habitat:
○ ?? in man and natural water environment
○ Freshwater amoebae → natural reservoir

● Transmission:
aerosols from ??
○ no human to human transmission

A

Legionella pneumophila
-ubiquitous
-airconditioning systems

23
Q

Pathogenesis of L. pneumophila:

○ Endotoxin: ??
● Protect the bacteria from
macrophage superoxide and
hydroperoxide oxidative burst

○ ??
■ Promote attachment and invasion

○ RNAse, Phospholipase A and Phospholipase C

○ Organism replicate intracellularly
■ Inhibits ??

A

Cu-Zn superoxide dismutase and
Catalase peroxidase
-pili and flagella
-phagolysosomal fusion

24
Q

Predisposing factors for L. pneumophila

A

○ Smokers
○ >55 yrs old
○ High alcohol intake
○ immunocompromised/ immunosuppression

25
Q

Diagnostics for L. pneumophila:

○ Visualized using ??

○ Culture on ??
■ Fastidious, require iron & cysteine

○ Organisms are dormant ?? and
are killed at temperatures ??

○ ?? Test:
■ can be detected by RIA with high sensitivity and specificity and will remain positive for months after infection

A

Silver stain
- Charcoal Yeast Extract Agar
-<20C, >60C
-Rapid Urinary Antigen test

26
Q

Diseases caused by L. pneumophila:

??
■ Pneumonia + Confusion + Non-bloody
diarrhea + Hyponatremia
■ Urinalysis: Proteinuria and Hematuria

??
■ Pneumonitis
■ Mild, flu-like illness

A

Legionnaires’ disease (atypical pneumonia)
Pontiac fever

27
Q

Treatment for L. pneumophila

A

Fluoroquinolones OR
Macrolides: Azithromycin, Erythromycin

28
Q

● Gram negative rods, in singly
○ Large, heterogeneous group of gram-negative rods whose natural habitat is the ?? of humans and animals

● All are ???

● Most of them are Motile → they have a ??
○ motile enterobacteriaea??

Can grow on ordinary culture media
○ They are not ?? [i.e. not difficult to grow]
● Ferment ??
● Catalase ??, Oxidase ??

A

Enterobacteriacaea/coliforms
-intestinal tract
-Facultative anaerobes
-peritrichous flagella
-Klebsiella, Shigella, Yersina [KeYS]
-fastidious
-glucose
-cat +, oxidase -

29
Q

Oxidase (+) gram negative bacilli/rods
like ??

A

V. cholera and Campylobacter

30
Q

Enterobacteriacaea antigen
■ the most external part of the cell wall
lipopolysaccharide
■ consist of repeating units of polysaccharide
■ resistant to heat and alcohol and usually
are detected by ??
■ predominantly ??

A

O: cell envelope
-bacterial agglutination
-IgM

31
Q

Enterobacteriacaea antigen

■ located on flagella
■ denatured or removed by heat or alcohol
■ agglutinate with ?? antibodies, mainly ??

A

H: flagellar
-anti-H
-IgG

32
Q

Enterobacteriacaea antigen

■ external to O antigens on some but not all
Enterobacteriaceae
■ may be associated with virulence:
● E coli strains producing ?? antigens are prominent in ??
● ?? antigens of E coli cause attachment of the bacteria to epithelial cells before GI or UT
invasion

A

K: capsular polysaccharide
-K1
-neonatal meningitis

33
Q

Enterobacteriacaea antigen of Salmonella

A

Vi: capsular antigen

34
Q

Enterobacteriacaea that are LF

A

Citrobacter
Escherichia
Enterobacter
Klebsiella

35
Q

Enterobacteriacaea that are NLF

A

Shigella
Yersinia
Proteus
Salmonella

36
Q

Facultative anaerobe
-LF
-Iridescent green sheen on EMB “??”
-+/- capsule

A

Escherichia coli
-greenish metallic sheen on EMB

37
Q

Habitat of E. coli

● Transmission of E. coli
○ most common ??
○ During birth in ??
○ ?? in cases of diarrhea

A

Human colon (also vagina, urethra)
-Ascending infection in UTI
-neonatal meningitis
-Fecal oral route

38
Q

Virulence Factors of E. coli:

  1. ??
    ■ Attachment, colonization factor associated
    with UTI
  2. ??
  3. ??
    ■ Associated with pneumonia and neonatal
    meningitis
  4. ??
  5. Enterotoxins
    ■ ?? → activates the enzyme guanylate cyclase
    ■ ?? → activates the enzyme adenylate cyclase
    ■ These events in turn cause watery diarrhea
    → increasing the activity of ?? [similar to the mechanism of Cholera toxin]
  6. ??
    ■ Bloody diarrhea [??]
    ■ Inhibits protein synthesis by inactivating
    the 60S Subunit of Eukaryotic cells
    ■ E.coli O157:H7, STEC, EHEC
A

-Pili or fimbriae
-Flagellum [H]
-Capsule [K]
-Endotoxin [O]

-ST [Stable Toxins A and B]
-LT [Labile Toxins I and II]
-cAMP

-Verotoxin [Shiga-like toxin]
-HUS

39
Q

Diseases caused by E. coli:

○ ??
■ Most common cause of community
acquired __
■ ?? (adherence to uroepithelium)
■ Treatment:
● ?? OR
● ??

○ ??
■ 2nd most common cause
■ capsule & endotoxin
■ Treatment:
● ?? for meningitis and sepsis

○ Diarrhea
■ ?? is effective in traveler’s
diarrhea

A

Urinary Tract Infection
-P-pili
-Ampicillin, Sulfonamides

Neonatal septicemia & meningitis
-3rd gen cephalosphorins

Rehydration

40
Q

E. coli strain

Epidemiology: traveler’s, children
Clinical syndrome: ??

A

ETEC
-watery diarrhea

41
Q

E. coli strain

Epidemiology: occ epidemics, children
Clinical syndrome: ??

A

EIEC
-dysentery

42
Q

E. coli strain

Epidemiology: infants in developing countries
Clinical syndrome: ??

A

EPEC
-watery diarrhea

43
Q

E. coli strain

Epidemiology: outbreaks in all ages
Clinical syndrome: ??

A

EHEC
-bloody diarrhea

44
Q

E. coli strain

Epidemiology: children
Clinical syndrome: ??

A

EAEC
DAEC
-persistent diarrhea

45
Q

Prevention of E. coli infection

A

○ Limiting urinary catheterization
○ Switching IV lines promptly
○ Drinking boiled water

46
Q

Facultative gram-negative rods
● Habitat
○ Human colon only! [??]
○ Enteric tract of humans and animals, chickens and domestic livestock [??]

A

Salmonella
-S. typhi and S. paratyphi
-S. enteritidis

47
Q

Salmonella infection induces carcinogenesis potentially through 4 paths namely:

★ The host is preconditioned by DNA damage caused by ?? factors (Western diet, obesity and physical inactivity) and ?? factors (tumor susceptibility)

★ Salmonella effector protein ?? stabilizes the expression of tight junction proteins (e.g., ZO-1) and decreases inflammation.
○ Meanwhile, Salmonella targets the “leaky protein” ?? to facilitate bacterial invasion.
○ The balance between protection and injury
contributes to chronic infection and leads to
sustained epithelial cell injury and DNA mutation.

★ Salmonella competes with indigenous microbiota for intestinal ??, thereby disrupting the gut microbiome and overcoming colonization resistance

★ ?? effectors enter epithelial cells and activate signaling pathways leading to chronic inflammation, host cell transformation, and carcinogenesis.

A

-epigenetic, genetic
-AvrA, claudin-2
-epithelial attachment sites and nutrients
-T3SS

48
Q

Diagnosis of Salmonella

○ ??-fermenting
○ Produces ??
○ ??
■ Detects antibodies in patient’s serum
○ Cultured in ??

A

-Non lactose
-H2S
-Widal Test
-XLD medium

49
Q

○ Most common form → due to animal acquired salmonella

○ Most common serotype: ??

○ Incubation period: 8-48 hours

○ S/sx:
■ Nausea, Vomiting
■ Headache
■ ?? diarrhea

○ Often self-limited

○ Mngt:
■ Give fluid and electrolyte replacement
■ Not required to give antibiotics
■ Infection limited to the gut → infective
dose is ??

A

Gastroenteritis / Enterocolitis or Salmonellosis
-Typhimurium
-Profuse non bloody
-10^5

50
Q

Clinical symptoms and excretion of salmonellae may be ?? by antimicrobial therapy

A

prolonged

51
Q

○ Typhoid and Paratyphoid fever
○ Typhoid caused by Salmonella typhi
○ Paratyphoid
■ Salmonella Paratyphi A
■ Salmonella ??
● Formerly Paratyphi B
■ Salmonella ??
● Formerly Paratyphi C
■ ?? is milder than Typhoid

A

Enteric fever
-Schottmuelleri
-Hirschfeldii
-Parathyroid

Micro (1 decks)

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