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M3 Flashcards

1
Q

NEISSERIA MENINGITIDIS

Gram? Shape?
Capsule?
Oxidase?
Ferments?

A

• gram-negative “kidney-bean” diplococci
• large polysaccharide capsule
• oxidase-positive colonies on chocolate agar
• ferments maltose and glucose

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2
Q

NEISSERIA MENINGITIDIS

HABITAT AND TRANSMISSION

A

• habitat is the URT
• transmission via respiratory droplets
• humans are the only natural hosts
• complement deficiencies in the late-acting complement
components (C5b–C9) predispose to illness
• high carriage rate in close quarters
o military recruits, dormitories, camps, travel (e.g., epidemic related to traveling to Saudi Arabia for the Hajj pilgrimage)

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3
Q

NEISSERIA MENINGITIDIS
PATHOGENESIS

A

• antiphagocytic polysaccharide capsule
• endotoxin (LPS)- highest level of endotoxin measured in sepsis
• Porin proteins- controls nutrient diffusion
• Opa- attachment
• Pili- binding to nasopharyngeal epithelial cells

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4
Q

NEISSERIA MENINGITIDIS
Portalof entry

A

Nasopharynx

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5
Q

highest level of endotoxin measured in sepsis

A

endotoxin (LPS)

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6
Q

NEISSERIA MENINGITIDIS
SPECTRUM OF DISEASE

A

Meningitis
Meningococcemia
Waterhouse-Friderichsen Syndrome

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7
Q

most common cause of meningitis among aged 2-18 yrs

Manifestation?

A

NEISSERIA MENINGITIDIS

fever, headache, stiff neck, and an increased level of PMNs in spinal fluid

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8
Q

o dissemination of meningococci into the bloodstream
o multiorgan disease, consumptive coagulopathy, petechial or
purpuric rash (purpura fulminans)

A

Meningococcemia

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9
Q

most severe form of meningococcemia

A

Waterhouse-Friderichsen Syndrome

o high fever, shock, widespread purpura, disseminated
intravascular coagulation, thrombocytopenia, and adrenal
insufficiency
§ bilateral hemorrhagic destruction of the adrenal glands

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10
Q

NEISSERIA MENINGITIDIS

TREATMENT

A

penicillin G

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11
Q

NEISSERIA MENINGITIDIS

vaccine contains capsular polysaccharide of strains

A

A, C, Y, and
W-135

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12
Q

Post-exposure prophylaxis to close contacts

A

o Rifampicin
o Ciprofloxacin
o Ceftriaxone

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13
Q

Which of the following virulence factors allows adherence of bacteria
to the mucous membranes of the respiratory, genitourinary and
gastrointestinal tracts?
A. Panton-Valentine Leukocidin
B. Hyaluronidase
C. Coagulase
D. IgA protease

A

D. IgA protease

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14
Q

Which capsular type of Neisseria meningitidis lacks immunogenicity
even with protein conjugation, hence, not included in the vaccine?
A. A
B. B
C. C
D. Y
E. W-135

A

B. B

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15
Q

NEISSERIA GONORRHOEAE
Gram? Shape?
Capsule?
Oxidase?
Ferments?

A

• gram-negative “kidney-bean” diplococci
• insignificant capsule
• oxidase-positive colonies on Thayer-Martin medium
• ferment glucose only

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16
Q

The modified Thayer-Martin medium contains which antibiotics?
A. Voriconazole, cefuroxime, netilmicin
B. Vancomycin, colistin, nystatin
C. Vancomycin, ciprofloxacin, neosporin
D. Voriconazole, cotrimoxazole, nystatin

A

B. Vancomycin, colistin, nystatin

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17
Q

NEISSERIA GONORRHOEAE

HABITAT AND TRANSMISSION

A

• habitat is the human genital tract
• transmission by sexual contact or during passage through birth canal
• complement deficiencies in the late-acting complement
components (C5b–C9) predispose to illness
o cannot form membrane-attack complexes

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18
Q

NEISSERIA GONORRHOEAE

PATHOGENESIS

A

IgA protease – destroys mucosal antibodies that would inhibit
epithelial colonization
• Lipooligosaccharide (LOS) – devoid of long O-antigen side
chains, toxicity of gonococcal infections largely attributable to LOS
• Opa – adhesion of gonococci within colonies and attachment to
host cell receptors, expression results in opaque colonies
• Pili – enhances attachment to host cells, made up of pilin proteins
that are antigenically distinct (accounts for antigenic variation)
• usual co-infection with Chlamydia trachomatis

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19
Q

most common cause of urethritis
most common cause of PID
most common cause in sexually active adults

A

NEISSERIA GONORRHOEAE

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20
Q

NEISSERIA GONORRHOEAE

SPECTRUM OF DISEASE: LOCALIZED

A

Ophthalmia Neonatorum
o purulent conjunctivitis in newborns

• Gonococcal Urethritis
o urethritis and epididymitis in men

• Pelvic Inflammatory Disease
complications:
§ sterility
§ ectopic pregnancy
§ chronic pelvic pain
§ dyspareunia
§ Fitz-Hugh-Curtis syndrome (perihepatitis): violin-string
adhesions

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21
Q

NEISSERIA GONORRHOEAE

SPECTRUM OF DISEASE: DISSEMINATED

A

Septic Arthritis

o arthritis, tenosynovitis, or pustules in the skin

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22
Q

gold standard for the
diagnosis of gonorrheal infections

A

Nucleic acid amplification test (NAAT)

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23
Q

NEISSERIA GONORRHOEAE

Culture Appearance

A

• “Opaque Colonies” = specimen came from symptomatic male
(urethritis) OR midcycle uterine culture
• “Transparent Colonies” = specimen came from asymptomatic male
OR menstruating women OR invasive / disseminated gonorrhea

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24
Q

Presumptive Diagnosis of Gonorrhea

If Male, (+) microscopic from Urethral specimen:

A

NO OTHER TESTS
NEEDED

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25
Q

Presumptive Diagnosis of Gonorrhea

If Female, (+) microscopic Endocervix specimen:

A

Do NAAT or
CULTURE

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26
Q

NEISSERIA GONORRHOEAE

TREATMENT

A

• Single dose of ceftriaxone 500 mg IM (intramuscular injection)
• For completeness, also consider the treatment for possible coinfection
with chlamydia. The CDC recommends treating with doxycycline 100
mg orally twice a day for 7 days, unless contraindicated (e.g., in pregnancy, where azithromycin is preferred)

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27
Q

A 26-year-old male presents to his primary care physician with
complaints of burning with urination, penile discharge, and
intermittent fevers. A urethral smear shows gram negative diplococci
within white blood cells. The organism grows well when cultured on
Thayer-Martin agar. The patient is prescribed a course of ceftriaxone,
and the infection resolves without further complication. One year
later, the patient returns with the same infection. Which of the
following best explains this lack of lasting immunity?

A. Antigenic variation
B. Polysaccharide capsule
C. Bruton’s agammaglobulinemia
D. Lack of necessary vaccination
E. HIV infection

A

A. Antigenic variation

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28
Q

A 22-year-old sexually active man complains of purulent urethral
discharge and dysuria after having unprotected sex at a college
party. Which of the following is the most sensitive test to diagnose
the most likely causative agent?
A. Gram stain of the urethral discharge
B. Culture
C. Serology
D. Nucleic acid amplification test

A

D. Nucleic acid amplification test

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29
Q

2 weeks later, the patient comes back to the clinic complaining of
persistence of urethral discharge. What is the best test to order to
reevaluate his case?
A. Gram stain of the urethral discharge
B. Culture
C. Serology
D. Nucleic acid amplification test

A

B. Culture

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30
Q

N. gonorrhea is the most common cause of _____
bacterial conjunctivitis in adults

A

Hyperacute

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31
Q

In which of the following exudate specimen can a positive smear for
Neisseria gonorrhoeae be a basis for presumptive diagnosis of
gonorrhea and start treatment without additional laboratory test?
a. Throat
b. Endocervical
c. Urethral
d. Rectal

A

c. Urethral

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32
Q

NEISSERIA MENINGITIDIS
Most common form of infection:

A

Asymptomatic carriage

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33
Q

Waterhouse Friderichsen Syndrome

Also known as
Manifests as:

A

○ hemorrhagic adrenalitis
○ Fulminant meningoccocemia

○ Adrenal gland failure due to bleeding into the adrenal glands caused by severe bacterial infection, most commonly due to

■ Hyponatremia
■ Hyperkalemia
■ Hypoglycemia

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34
Q

Which of the following is the most widely used prophylactic drug for
meningococcemia in the local setting?
a. Rifampicin
b. Ceftriaxone
c. Ciprofloxacin
d. Penicillin G

A

c. Ciprofloxacin

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35
Q

gram negative rods

enriched chocolate agar,
Polyribitol phosphate
capsule

A

Haemophilus
influenzae type b

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36
Q

gram negative rods

Bordet-Gengou agar,
whooping cough

A

Bordetella
pertussis

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37
Q

gram negative rods

poorly gram staining, silver
stain, charcoal yeast agar,
air-conditioning

A

Legionella
pneumophila

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38
Q

HAEMOPHILUS INFLUENZAE

Gram? Shape?
Fastidious?
Requires?
Hemolysis?
Quellung test?

A

small gram-negative (coccobacillary) rods
fastidious organism
X HEMIN
V NAD
Hemolysis -
Satellite phenomenon
Quellung test +

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39
Q

HAEMOPHILUS INFLUENZAE

HABITAT AND TRANSMISSION

A

• habitat is upper respiratory tract
• transmission via respiratory droplets

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40
Q

HAEMOPHILUS INFLUENZAE

PATHOGENESIS

A

type b (Polyribitol phosphate) = 95% of invasive disease

IgA protease

41
Q

Haemophilus Type B:

SPECTRUM OF DISEASE

A

Meningitis, Pneumonia, Bacteremia,
Epiglottitis

42
Q

most common cause of epiglottitis

Characteristic?
Sign?

A

HAEMOPHILUS INFLUENZAE

Cherry red epiglottitis
Thumb sign
Omega sign

43
Q

Non-Typeable:

SPECTRUM OF DISEASE

A

Conjunctivitis, Otitis Media, COPD exacerbation,
Sinusitis

44
Q

HAEMOPHILUS INFLUENZAE

TREATMENT

A

Ceftriaxone

45
Q

BORDETELLA PERTUSSIS
Gram?
Culture?
Capsule
Oxidase
Urease

A

• small gram-negative rods
• culture on Bordet-Gengou agar or Regan-Lowe charcoal medium
Capsule +
Oxidase +
Urease -

46
Q

BORDETELLA PERTUSSIS

HABITAT AND TRANSMISSION

A

• habitat is upper respiratory tract
• transmission via respiratory droplets

47
Q

BORDETELLA PERTUSSIS

PATHOGENESIS

A

• filamentous hemagglutinin
o pili rod that extends from the surface of B. pertussis, enabling
the bacteria to bind to ciliated epithelial cells of the bronchi
o mediates attachment
• pertussis toxin
o causes ADP-ribosylation
o activates G proteins that increases cAMP resulting in:
§ increased sensitivity to histamine
§ increased insulin release
§ peripheral lymphocytosis
• extracytoplasmic (false) adenylate cyclase
o ‘weakens’ neutrophils lymphocytes and monocytes
o inhibits phagocytosis
• tracheal cytotoxin
o damages ciliated cells
o causes whooping

48
Q

BORDETELLA PERTUSSIS

SPECTRUM OF DISEASE

Incubation period?
Phases?

A

Pertussis or Tuspirina

• Incubation Period
o 7-10 days
• Catarrhal phase
o 1-2 weeks
o rhinorrhea, malaise, fever, sneezing, anorexia
o ANTIBIOTICS MOST EFFECTIVE
• Paroxysmal phase
o 2-4 weeks
o ‘Whoop’ → burst of non-productive coughs
o Increased number of lymphocytes in blood smear
o ANTIBIOTICS INEFFECTIVE during this stage
• Convalescent stage
o 3-4 weeks (or longer)
o Diminished paroxysmal cough
o Development of secondary complications (pneumonia,
seizure, encephalopathy)

49
Q

BORDETELLA PERTUSSIS
TREATMENT
PREVENTION

A

Erythromycin

acellular vaccine in combination with diphtheria and tetanus
toxoids (DTaP)

50
Q

LEGIONELLA PNEUMOPHILA
Gram?
Culture?

A

• poorly gram-negative rods
o visualize with silver stain

• facultative intracellular bacteria

• culture on charcoal yeast extract agar
o increased amounts of iron and cysteine
o optimal 28 to 40°C; dormant below
20°C and
killed above 60°C

51
Q

Urine antigen test
only detects

A

L. pneumophilia serogroup 1

52
Q

FACULTATIVE INTRACELLULAR BACTERIA

A

Salmonella
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia

53
Q

LEGIONELLA PNEUMOPHILA

HABITAT AND TRANSMISSION

A

natural water environments

transmission via inhalation from aerosols

54
Q

LEGIONELLA PNEUMOPHILA

predisposing factors

A

o old age, smoking, high alcohol intake, immunosuppression

55
Q

Legionnaires’

Clinical
features

Radiographic
pneumonia

Incubation
period

A

Pneumonia
Cough
Fever

Yes - hazy infiltrates

2-14 days after exposure

56
Q

Pontiac Fever

Clinical
features

Radiographic
pneumonia

Incubation
period

A

Flu-like illness
Without pneumonia

No

24-72 hrs afterexposure

57
Q

23/M fishpond cleaner developed fever, cough, and body weakness. If you are suspecting Pontiac fever because of the occupational history, which of the following CXR findings would you expect?
a. Hazy infiltrates on upper and middle lobes
b. Consolidation, empyema, pneumatoceles
c. Doughnut signs
d. Negative chest

A

d. Negative chest

58
Q

ESCHERICHIA COLI
Gram
Lactose
Antigen

A

• facultative gram-negative rods
• lactose-fermenting colonies on
EMB or MacConkey agar
• green sheen on EMB agar;
metallic sheen
• typing by O and H antigens

59
Q

ESCHERICHIA COLI

HABITAT AND TRANSMISSION

A

• habitat is human colon
• colonizes the vagina and urethra
• transmission
o ascending infection in UTI
o during birth in neonatal meningitis
o fecal–oral route in diarrhea

60
Q

ESCHERICHIA COLI

PATHOGENESIS

A

• pili or fimbriae – attachment, colonization factor, associated
with UTI (cystitis, pyelonephritis)
• flagellum (H)
• capsule (K) – associated with pneumonia and neonatal meningitis (K1)
• endotoxin (O)
• enterotoxins
o ST and LT cause watery diarrhea, increase cAMP (similar to
cholera toxin)
o verotoxin (Shiga-like toxin) causes bloody diarrhea (HUS),
inhibits protein synthesis by inactivating the 60S subunit
of eukaryotic cells (E. coli O157:H7, STEC, EHEC)

61
Q

E.COLI ENTEROTOXIN

A

ST: cGmp
LT: cAmp

62
Q

ENTEROBACTERIACEAE

Think MESSY SPECK!
Enterobacteria drink COFFEe!

A

Morganella Serratia

Escherichia Proteus
Shigella Enterobacter
Salmonella Citrobacter
Yersinia Klebsiella

Capsular antigen (K)
O antigen
Flagellar antigen (H)
Ferments glucose
Enterobacteriaceae

63
Q

most common cause of community-acquired UTI

A

ESCHERICHIA COLI

64
Q

2nd most common cause

A

ESCHERICHIA COLI

65
Q

NEONATAL MENINGITIS

A

S – L – E
S. agalactiae (GBS)
Listeria monocytogenes
Escherichia coli

66
Q

Enterotoxigenic
E. coli (ETEC)

Aka
Syndrome
Unique
Site
Toxin

A

Montesumas revenge
Travellers diarrhea

Watery diarrhea

Cholera-like manifestation

Small intestine

Heat labile -inc camp
Stable toxin -inc cgmp

67
Q

Enteropathogenic
E. coli (EPEC)

Syndrome
Unique
Site
Toxin

A

Watery diarrhea

infants

Small
Intestine

No toxin
produced.
Flattens villi.

68
Q

Enterohemorrhagic
E. coli (EHEC)

Aka
Syndrome
Unique
Site

A

Shiga like toxin e coli (stec)
Hamburger
O157; H7

Bloody diarrhea; hemorrhagic colitis
and hemolytic
uremic syndrome
(HUS)

Has shiga-like
toxin/ verotoxin STX 1 and STX 2

Large intestine
Undercooked meat

69
Q

Enteroinvasive
E. coli (EIEC)

SYNDROME
Unique

A

Bloody diarrhea
Dysentery
Mucus, fever, pus

Shigella-like manifestation

Large intestine

Enterotoxin

70
Q

Enteroaggregative
E. coli (EAEC)

Syndrome
Unique

A

Persistent watery
diarrhea in children
and patients infected
with HIV
Prolonged

Entero-
aggregative
heat-stable

71
Q

Loss of water and electrolytes

A

ETEC

72
Q

Flattening of villi
Less absorption of water

A

EPEC

73
Q
  • protein synthesis at 60 ribosomal subnit
A

EHEC/STEC

74
Q

Flattening of villi + aggregation
Less absorption of water

A

EAEC

75
Q

Destruction of enterocyte tissue inflam process

A

EIEC

76
Q

Same with EAEC

A

Diffused aggregative e.coli

77
Q

Hemolytic Uremic Syndrome
_____ is the most prominent serotype
Triad of:

A

O157:H7

hemolytic anemia, thrombocytopenia, and uremia

78
Q

Pyogenic Liver Abscess

Clinical manifestation?
Most frequent on ____ lobe
_____ if needed

A

RUQ pain, fever, jaundice

right

Percutaneous aspiration

79
Q

Pyogenic Liver Abscess

Clinical manifestation?
Most frequent on ____ lobe
_____ if needed

A

RUQ pain, fever, jaundice

right

Percutaneous aspiration

80
Q

ESCHERICHIA COLI

SPECTRUM OF DISEASE

A

Urinary Tract Infection

Neonatal Meningitis

Intestinal Infections

Hemolytic Uremic Syndrome

Pyogenic Liver Abscess

81
Q

ESCHERICHIA COLI

TREATMENT
• for UTI
• for meningitis and sepsis
• effective in traveler’s diarrhea

A

ampicillin or sulfonamides

3° cephalosporins

rehydration is

82
Q

A 27-year-old male suddenly develops severe abdominal
cramping and bloody diarrhea. The patient reports consuming rare hamburger four days prior to the onset of the symptoms.
Which of the following best describes the toxin-mediated mechanism of this disease process?

A. Depolymerization of actin filaments in gastrointestinal mucosal cells, leading to mucosal cell death
B. Increased intracellular cAMP in gastrointestinal mucosal cells, resulting in decreased absorption and increased secretion in the
digestive tract
C. Inhibition of elongation factor-2 (EF-2), resulting in decreased protein synthesis in gastrointestinal mucosal cells
D. Inhibition of the 60S ribosomal subunit, resulting in decreased protein synthesis in gastrointestinal mucosal cells

A

D. Inhibition of the 60S ribosomal subunit, resulting in decreased protein synthesis in gastrointestinal mucosal cells

83
Q

cause
depolymerization of actin filaments in gastrointestinal mucosal
cells, leading to mucosal cell death (i.e., pseudomembranes)

A

Exotoxin A and B of Clostridioides difficile

84
Q

increases intracellular cAMP in gastrointestinal
mucosal cells, resulting in decreased absorption and increased
secretion in the digestive tract

A

Cholera toxin

85
Q

inhibits elongation
factor-2 (EF-2), resulting in decreased protein synthesis in gastrointestinal mucosal cells

A

Exotoxin A of Pseudomonas aeruginosa

86
Q

Gram-negative rod Lactose fermenter, green sheen

A

Escherichia coli

87
Q

Gram-negative rods Lactose fermenter, urease positive, ESBL

A

Klebsiella pneumoniae

88
Q

Gram-negative rods Comma-shaped, motile, oxidase positive

A

Vibrio cholerae

89
Q

Gram-negative rods Comma-shaped, microaerophilic, Skirrow’s agar

A

Campylobacter jejuni

90
Q

Gram-negative rods Comma-shaped, urease positive

A

Helicobacter pylori

91
Q

Gram-negative rods Comma-shaped, urease positive

A

Helicobacter pylori

92
Q

non-lactose-fermenting, gram negative rods

motile, oxidase negative, H2S producer

A

Salmonella spp.

93
Q

non-lactose-fermenting, gram negative rods
non-motile, oxidase negative, H2S non producer

A

Shigella spp.

94
Q

non-lactose-fermenting, gram negative rods
swarming, oxidase negative, H2S producer, urease

A

Proteus mirabilis

95
Q

non-lactose-fermenting, gram negative rods
oxidase positive, H2S non producer, obligate aerobe

A

Pseudomonas aeruginosa

96
Q

Lactose fermented rapidly

metallic sheen on differential media; motile; flat, non-viscous colonies

raised colonies, no metallic sheen; often motile; more viscous growth

similar to Enterobacter aerogenes

very viscous, mucoid growth; non-motile

A

• Escherichia coli

• Enterobacter aerogenes

• Enterobacter cloacae

• Klebsiella pneumoniae

97
Q

Lactose fermented slowly

A

• Edwardsiella, Serratia, Citrobacter, Arizona, Providencia, Erwinia

98
Q

Lactose not fermented

non-motile; no gas from dextrose

motile; acid and usually gas from dextrose

“swarming” on agar; urea rapidly hydrolyzed
(smell of ammonia)

soluble pigments, blue-green and fluorescing; sweetish smell

A

• Shigella species
• Salmonella species
• Proteus species
• Pseudomonas species
Providencia
Morganella

03 (4 decks)

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