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Flashcards in Micro Deck (45):
1

Classic signs of leprosy

Loss of sensation on the cool parts of the body associated with granuloma formation from acid fast bacilli

2

To what would a patient be susceptible if they wre deficient in the C5 complement protein?

Gram-negative bacteria, especially Neisseria species

3

gram-positive, catalase-negative, alpha-hemolytic diplococcus

streptococcus pneumoniae
viridans streptococci

4

atypical fungus

pneumocystis jiroveci

5

gram-negative, catalase-positive bacillus

pseudomonas aeruginosa

gram negative
rod (bacillus)
lactose nonfermenter
oxidase positive

6

gram-positive, catalase-positive, beta-hemolytic coccus in clusters

staphylococcus aureus

7

What is a common cause of pneumonia in patients with cystic fibrosis?

pseudomonas

8

gram + cocci
catalase +
coagulase +

s. aureus

9

gram+ cocci
catalase +
coagulase -

s. epidermidis (novobiocin sensitive)
s. saprophyticus (novobiocin resistant)

10

gram + cocci
catalase -
alpha-hemolytic

s. pneumoniae (capsule, optochin sensitive, bile soluble)
viridans streptococci (no capsule, optochin resistant, bile insoluble)

11

gram + cocci
catalase -
beta-hemolytic

s. pyogenes (bacitracin sensitive) (group A)
s. agalactiae (bacitracin resistant) (group B)

12

gram + cocci
catalase -
gamma-hemolytic

group D (enterococcus, e.g., E. faecalis) - growth in bile and 6.5% NaCl

Nonenterococcus (S. bovis) - growth in bile, not in 6.5% NaCl

13

gram + bacilli

clostridium (anaerobic)
bacillus (aerobic)
corynebacterium
mycobacterium tuberculosis (acid fast)
listeria monocytogenes (beta-hemolytic)

14

gram + branching filaments

nocardia - aerobic, acid fast
actinomyces - anaerobic, not acid fast

15

gram - diplococci

Neisseria meningitidis (maltose fermenter)
Neisseria gonorrhoeae (maltose nonfermenter)

Both produce IgA protease and ferment glucose

16

gram - "coccoid" rods

Haemophilus influenza
Bordatella pertussis

17

gram - rods
lactose fermenters

Fast:
Klebsiella
E. Coli
enterobacter

Slow:
citrobacter
serratia

18

gram - rods
lactose nonfermenters

oxidase (-):
shigella
salmonella
proteus
yersinia

oxidase (+)
pseudomonas

19

gram (-) comma-shaped
oxidase +

campylobacter jejuni (grows in 42 degrees)
helicobacter pylori (produces urease)
vibrio cholerae (grows in alkaline media)

20

Characteristics of Salmonella

-has flagella
-hematogenous spread
-produces hydrogen sulfide
-intestinal epithelial invasion --> monocytic response
-may cause bloody diarrhea
-has many animal reserviors
-antibiotics may prolong duration fecal excretion of organism
-does not ferment lactose

21

Characteristics of shigella

-no flagella
-cell-to-cell transmission (no hematogenous spread)
-does not produce hydgrogen sulfide
-intestinal epithelial invasion --> neutrophilic response
-often causes bloody diarrhea
-only found in humans and primates
-antibiotics shorten duration of fecal excretion of organism
-does not ferment lactose

22

Characteristics of N. gonorrhoeae

(1) no pollysaccharide capsule
(2) does not ferment maltose
(3) sexually transmitted
(4) no vaccine (due to rapid antigenic variation in pilus protein
(5) leads to: gonorrhea, septic arthritis, pelvic inflammatory disease, neonatal conjunctivitis, Fitz-Hugh_Curtis Syndrome
(6) condoms prevent sexual transmission; erythromycin ointment prevent neonatal transmission
(7) treatment: ceftriaxone (+ doxycycline or azithromycin for possible chlamydia infection)
(8) often intracellular (in neutrophils)

23

Characteristics of N. meningitidis

(1) polysaccharide capsule
(2) ferments maltose
(3) respiratory and oral secretions
(4) vaccine available (except for type B)
(5) leads to: meningococcemia, meningitis, Waterhouse-Friderichsen syndrome
(6) rifampin, ciprofloxacin, or ceftriaxone prophylaxis for close contacts
(7) treatment: ceftriaxone or penicillin G

24

Common characteristics of Neisseria

--gram negative
--diplococci
--ferment glucose
--produce IgA proteases

25

Klebsiella characteristics

Four As:

(1) Aspiration pneumonia (lobar)
(2) Abscess formation in lungs and liver
(3) Alcoholics
(4) diAbetics

Patients often produce "red currant jelly" sputum due to abundant polysaccharide capsules

26

Whats the relationship between penicillin and gram-negative bugs?

Gram (-) bacilli are resistant to penicillin G but may be susceptible to penicillin derivatives such as ampicillin and amoxicillin.

The gram negative outer membrane layer inhibits entry of penicillin G and vancomycin

27

Beta-hemolytic bacteria

Form a clear area of hemolysis on blood agar

streptococcus pyogenes
streptococcus agalactiae
staphylococcus aureus
listeria monocytogenes

28

What microorganism causes syphilis?

Treponema pallidum

29

Describe primary syphilis.

(presentation, serology/diagnosis)

--localized disease
--presents with painless, non-itchy, nodule (chancre)
--screen with: VDRL, RPR
--confirm diagnosis with FTA-ABS
--can use dark-field microscopy to visualize treponemes in fluid from chancre

30

What do VDRL, RPR and FTA-ABS stand for?

VDRL - venereal disease research laboratory
RPR - rapid plasma reagin
FTA-ABS - fluorescent treponemal antibody absorption

31

Describe secondary syphilis.

(presentation, screening/diagnosis)

--disseminated disease that presents with:

-fever
-lymphadenopathy
-maculopapullar rash, often including palms and soles
-condylomata lata - whitish, wart-like lesion on genitals

VDRL/RPR for screening, FTA-ABS for confirmation
Dark field microscopy to visualize treponemes

*Followed by latent syphilis - (+) serology, asymptomatic

32

Describe tertiary syphilis

(presentation, screening/diagnosis)

(1) gummatous syphilis (chronic granulomas)
(2) cardiovascular syphilis (aortitis, vaso vasorum destruction --> increased risk of aortic aneurysm)
(3) late neurosyphilis (tabes dorsalis, Argyll-Robertson pupil)
-->presents with broad-based ataxia, (+) Romberg sign, stroke without hypertension, Charcot joint

For neurosyphilis: test CSF with VDRL or RPR

33

What is VDRL?

venereal disease research laboratory
--detects nonspecific antibody that reacts with beef cardiolipin
--screening test for syphilis, sensitive, nonspecific, many false positives

34

Causes of false positives in VDRL test

VDRL:

Viruses (hepatitis, mononucleosis [EBV])
Drugs
Rheumatic fever
Lupus and leprosy

35

What is congenital syphilis?

syphilis present in utero and at birth

occurs when a child is born to a mother with syphilis

36

What are the clinical manifestations of neonatal syphilis?

Saber shins
Hutchinson teetch (notched incisors)
Mulberry molars
Saddle nose
CNVIII deafness
Often results in stillbirth, hydrops fetalis

37

How should you treat neonatal syphilis?

Treat the mother early in pregnancy, as placental transmission typically occurs after the first trimester.

38

What are the serological tests for HIV diagnosis?

--ELISA - highly sensitive test used for screening; has a high false positive rate; a positive must be confirmed with: --Western Blot - specific test; high false negative rate, used to "rule in"

39

What test is used to monitor HIV prognosis and effect of therapy

--HIV PCR/viral load - used to determine the amount of viral RNA in plasma.
--High viral load is associated with a poor prognosis
--Used to also monitor effect of drug therapy

40

What defines an AIDS diagnosis?

<14% of all lymphocytes

41

What do the ELISA and Western Blot tests look for?

antibodies produced to viral proteins

42

Why should ELISA and Western Blot tests be interpreted with caution?

These tests can be falsely negative in the first 1-2 months after HIV infection.

These tests can also be falsely positive initially in babies born to HIV positive mothers because the anti-gp120 antibody (IgG) crosses the placenta

43

Where does HIV replicate during the latent phase of the infection?

In the lymph nodes (where the CD4+ cells would normally be found)

44

What are the four general stages of untreated HIV infection?

(1) Flu-like symptoms
(2) Feeling fine (latent)
(3) Falling count (CD4+)
(4) Final crisis

45

How would you diagnose diphyllobothrium latum?

diagnost by finding operculated eggs or proglottids in feces