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753 - Micro > Quiz 3 > Flashcards

Quiz 3 Flashcards

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1
Q

Which species of Neisseria are clinically significant?

A

N. meningitidis
N. gonorrhoeae

Gonorrhea is not confined to genitals it can be seen in blood cultures and other body sites

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2
Q

What are the general characteristics of Neisseria?

A

diplococci, non-motile, aerobic, capsules found on pathogenic species (virulence factor)

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3
Q

Medically significant Neisseria

A

It can cause infection in pharyngeal region and move through the nasal cavity into the meninges (lining around the brain/spinal cord)

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4
Q

Meningitis

A

Can cause vascular collapse, hemorrhage and petechiae (trunk/extremities), intravascular clotting and death

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5
Q

What is the most common non-pathogenic Neisseria?

A

N. lactamica

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6
Q

How are Neisseria and related organisms divided?

A

group 1 - traditional pathogens
group 2 - commensal Neisseria, that can grow on selective media like MTM
group 3 - commensal Neisseria that usually doesn’t grow on selective media

Group 2/3 further classified by carbohydrate profile (saccharolytic/asaccharolytic)

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7
Q

Non-pathogenic Neisseria and how they affect immunocompromised people

A

Opportunistic infections (endocarditis, meningitis, otitis media, neonatal conjunctivitis and pneumonia

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8
Q

How is N. lactamica differentiates from other species of Neisseria?

A

Glucose, maltose and lactose +

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9
Q

Characteristics of Moraxella

A

Hockey puck colonies (SBA/Choc), asaccharolytic and + butyrate esterase

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10
Q

How to R/O Acinetobacter w/ other GNC

A

Its oxidase -

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11
Q

Sample collection/transport Neisseria

A

JEMBEC (incubate ASAP) plates for transport, dacron/rayon swab used for genital swab w/charcoal in medium to inhibit fatty acids

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12
Q

Antigen detection of Neisseria

A

CSF, urine, serum (not blood it dilutes the organism) Ag detected by latex agglutination assays

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13
Q

N. meningitis serotype B

A

Most virulent, shares a lot of cell membrane lipids that mimics our cell membrane lipids (virulence factor) which help it to avoid detection

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14
Q

Neisseria (antibiotics/vaccine)

A

Penicillin G to treat N. meningitis, N. gonorrhea is resistant to penicillin

Vaccine available - serotypes A, C, Y, W135

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15
Q

Features of Bacillus

A

Widely distributed through nature

  • thermophiles
  • plant or insect pathogens
  • used in autoclave/disinfectants
  • producers of antibotics/vitamins
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16
Q

Features of Bacillus cont…

A

Aerobes/facultative anaerobes, form endospores, catalase + (unlike clostridia)

  • fast growers (SBA)
  • lab contaminants
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17
Q

Which Bacillus species are associated with human disease?

A

B. anthracis

B. cereus

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18
Q

Bacillus anthracis

A
  • large GPR
  • flat, ground-glass/powdery
  • non-hemolytic
  • non-motile
  • sticky/tenacious consistency (stands up like beaten egg whites)
  • Does not grow on MAC
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19
Q

B. anthracis microscopic morphology

A
  • as culture ages, vegetative cells are easily decolorized

- spores are not always present

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20
Q

What are the 3 recognized forms (anthrax) in humans?

A
  • Cutaneous (most common) - cuts contaminated w/spores, eschar (depressed black necrotic ulcer)
  • inhalation of spores
  • gastrointestinal ingested spores in food (fatality rate higher than cutaneous)
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21
Q

B. cereus morphology

A

silver, beta hemolytic

box car shape, gram variable

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22
Q

B. cereus

A

Destroyed by properly cooking food

-causes food poisoning and serious rapid eye infections

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23
Q

Corynebacterium

A

Palisades, V/L GPR

  • animal/plant/human pathogens
  • both lipophilic/non-lipophilic
  • opportunistic
  • isolated from blood cultures/normal sterile sites
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24
Q

C. diphtheriae

A
  • diphtheria toxin
  • lysogenic bacteriophage carries tox gene
  • 2 different forms (human disease) respiratory (w/pseudomembrane) and cutaneous

-conjunctivitis, bull neck, myocarditis

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25
What media is used to culture C. diphtheriae?
Dacon, calicum alginate swab - cystine-tellurite (tinsdale) media -- black colonies w/brown halos
26
Can C. diphtheriae be treated w/ antibiotics?
No, the toxins will become activated and interact w/heart muscle can lead to cardiac failure
27
Erysipilothrix rhusipathiae
Grows on TSI slant even though its for GN organisms - H2S production - BRUSH LIKE PATTERN (test tube)
28
What infection does E. rhusipathiae cause?
skin infections (associated w/animals) farmers, vets, fish handlers
29
What does Lactobacillus resemble?
tiny alpha-hemolyic streptococci
30
What are the clinical settings of lactobacillus?
Normal vaginal, GIT flora and may cause meningitis and septicemia in immunocompromised
31
What are the normal genital flora?
Staph, corynebacteria, lactobacillus (women/reproductive age) enterobacteria, strepococcus
32
What happens when normal flora of the vagina go away?
pH levels increase normal flora (g. vaginalis, prevotella, peptostreptococci, mobiluncus and mycoplasma
33
How is bacterial vaginosis diagnosed?
Gram stain of vaginal discharge (use Nugent scoring system) - clue cell presence - almost absence or complete absence of lactobacilli
34
Diagnosis of Bacterial vaginosis cont...
milky discharge, pH more than 4.5, presence of clue cells, whiff test (fishy odor), lack of lactobacilli need at least 3 conditions for diagnosis Complications - chorioamniontis, preterm labor, still birth
35
Listeria monocytogenes
Single/short chains, beta hemolytic, tumbling motility, zoonotic UMBRELLA MOTILITY - test tube
36
What are the clinical settings of L. monocytogenes?
meningitis, septicemia of immunocompromised, stillbirth, gastroenteritis in immunocompentent hosts
37
Genus Mycobacterium
Obligate anerobes, intracellular, waxy coating on cell surface (mycolic acid), impervious to gram staining
38
2 pathogenic mycobacterium species
M. tuberculosis | M. leprae
39
What are some general characteristics of mycobacterium?
acid fast, aerobic, non-spore forming, non-motile, high lipid content cell wall, slow growing acid alcohol does not decolorize them
40
Stats of TB
1.6 million deaths 2017, 10 million new cases and 1.8 billion still have TB
41
Drug resistant TB
XDR-TB
42
Symptoms of TB
weakness, weight loss, chills, fever, child failure to thrive, coughing of blood, difficulty breathing
43
Out of the multiple members of M. tuberculosis complex, which ones infect humans?
M. tuberculosis, M. africanum, M. canetti
44
Runyon's classification - 4 groups
Gp I Photochromogens (yellow-orange pigment w/exposure to light, take 7 + days to grow) - M. kansasii Gp II Scotochromogens (yellow orange culture whether grown in dark or light, take 7 + days to grow) tap water M. gordonae GP III Nonchromogens - never produce pigments, take 7 + days to grow GP IV - rapid growers (grow < 7 days, they may or may not be pigmented)
45
Overview TB
TB is an aerosol transmissible disease (1-10 organisms = infectious)
46
What are normal flora of the lower respiratory tract?
- nonhemolytic streptococci - corynebacteria - coag (-) staph - stomatococcus mucilaginosa & nonpathogenic Neisseria spp.
47
Host resistance (lower respiratory infection)
Mucous, cilia, alveolar macrophages, secretory IgA, natural antibacterial substances in secretions (lysozyme)
48
What are the mechanisms of infection?
adherence, toxin production, host tissue damage, capsules, growth intracellularly
49
Examples of adherence factors
Lipoteichoic acids and M proteins (s. pyogenes) fimbriae (pili) of enterobacteria and other GNRs
50
Examples of toxin production
- Extracellular toxins of C. diphtheria, B. pertussis and P. aeruginosa - harmful enzymes produced by S. aureus and S. pyogenes (group A strep)
51
Examples of host damage by microbial growth
- the growth interferes w/normal host function | - growth triggers immune response
52
CHUM and its features
M. chelonae, M. haemophilum, M. ulcerans and M. marinum Isolated from skin and require lower primary recovery temps of 30-32*C
53
Safety rules for working with TB
Sterile, leak-proof, non breakable container - workers must be trained - meet level of competency Training (use of equipment, decontamination, spill clean-up, use of autoclave, waste disposal) Aerosol transmissible disease standard Testing must be done in a BSC level 3 Work 4-6" from grill, clean with tuberculocidal disinfectant Wear PPE
54
Sputum processing
Expectorated (deep, productive cough) and induced (w/ 5-10% hypertonic saline) 3-5 morning sputum specimens NaOH decontamination & NALC digestion
55
Acid-Fast Stains
Auramine-rhodamine (higher sensitivity, recommended by CDC, fluorescence microscope) Ziehl-Neelsen = carbolfuchsin (light microscope)
56
Media used to culture TB
Solid - egg based: LJ, agar based: Middlebrook 7H10, 7H11 Liquid - MGIT (BD), BacT/Alert (bioMerieux), Myco (VersaTrek)
57
Is sputum a valuable diagnostic specimen?
Yes, it is a non-invasive specimen, the etiologic agent of disease can sometimes be isolated It can also be No, sputum samples are contaminated with upper respiratory flora, its time consuming, collection is demanding of the patient and lab worker and delivery must be quick
58
What options are available for expectorated sputum?
- Induced sputum - gastric aspirate - bronchoscopy (bronchial wash is better than sputum but contaminated with URT flora, bronchoalveolar lavage) - lung biposy
59
What are 2 ways to detect streptococcal pharyngitis?
culture direct Ag testing of the throat specimen
60
Culture for S. pyogenes
sheep blood agar w/SXT disc stab culture or incubate anaerobically, capnophilic
61
Culturing for B. pertussis
Nasopharygeal swab, inoculate at bedside Bordet Gengou and charcoal based Regan-Lowe DFA/PCR to ID
62
Endogenous vs Iatrogenic Infections
Overgrowth of normally present organisms Introduced by medical procedures
63
Curable STDs
``` syphilis chancroid gonorrhea chlaymydial infection trichomoniasis ```
64
Syphilis vs Chancroid
Chancre: painless, uniform margin, firm/hard on touch GNR (train tracks) More common in US painful, oozing/irregular margins, softer to touch haemophilus ducreyi (X+V) school of fish
65
Curable STD's: Non-Ulcerative
Gonorrhea/chlamydia women usually asymptomatic Men - urethral discarge Trichomoniasis Women - vaginal discharge, Men - asymptomatic
66
Most common STD in US
Chlamydia - GN obligate intracellular bacteria C. psittaci - agent of bioterrorism Gonorrhea
67
Major life cycles of Chlamydia
Elementary bodies - reticulate body - inclusion
68
Elementary vs Reticulate body
Ele. infectious, metabolically inactive, smaller Ret. non-infectious, active, bigger
69
What disease does chlamydia cause
pelvic inflammatory disease, including endometritis
70
Detection/culture of chlamydia
Specimen added to McCoy cell layer in shell vial + results (c. trachomatis) DFA is more accurate and sensitive EIA/nucleic acid amp assay There is 1 assay that will detect (chlamydia, gonorrhea and trichomonas)
71
What diseases does N. gonorrhea cause
``` urethritis cervicitis conjunctivitis in newborns Pelvic inflammatory disease arthritis bacteremia ```
72
Gonorrhea cultures
Use stuart's and amies charcoal medium (culture w/in 12 hours) Selective Media - modified Thayer-Martin NYC medium JEMBEC plates Oxidase +
73
Antibiotics Used for media
Vancomycin for GP Colistin for GNR Trimethoprim for Proteis Nystatin for yeast
74
What is always performed w/gonorrhea
AST
75
Trichomoniasis
Urine samples wet mount (jerky movement) Rapid test - target trichomonas antigen
76
Syphilis
spirochete can't be gram stained - t. pallidum -once in macrocytes they can be spread to any part of body
77
Stages of syphilis
Primary - darkfield microscopy/DFA secondary - serological testing Latent - serological testing Tertiary - serological testing
78
Serological Testing of Syphilis
Non-treponemal tests - screening tests (VFRL/RPR) Treponemal tests - detects Ab specific to T. pallidum (FTA-ABS and MHA-TP)

753 - Micro (5 decks)

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