Mod. 6 & 7 - Normal Flora & Pathogens of the Skin, Eye, Ear and Respiratory Tract

Clinical Laboratory Science 214 with Stunkard at Northern Michigan University

About this deck

By: Kelsey Johnson
Created: 2011-11-11
Size: 42 flashcards
Views: 2

About StudyBlue

STUDYBLUE makes things that make you better at school. Things like online flashcards with photos and audio. Things like personalized quizzes and friendly reminders about when (and what) to study next. Think of it as a digital backpack™: access to all of your study materials online and on your phone. STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj

Sign up (free) to study this.

Staph aureus gram stain and bio. tests

gram positive cocci
catalase positive
coagulate positive
B-hemolytic

Scalded skin syndrome/Ritter's

s. aureus
necrosis of epidermis with little or no dermal involvement
exfoliative toxin - phage group 2
2-4 day duration

Impetigo

s. aureus
accute inflammation
ruptured pustules in the nares, face and extremities

Group A strep, Strep pyogenes gram stain and bio. tests

beta hemolytic
catalase neg.
resistant to SXT
sensitive to bacitracin, 0.04 units, A disc

Group A Strep Infections

Erysipelas

deep streptococcal infection, localized inflammation, erythematosis

Streptococcal TSS
Scarlet Fever

fine red "sandpaper" rash

Necrotizing Fascitis

Leprosy (Hansen's disease)

mycobacteria leprae
acid fast bacillus
prefers to grow at temps slightly lower than body temp
very slow growing
transmitted by respiratory droplets
armadillo: reservoir

Wound infections/abscesses

E. coli
S. aureus
S. pyogenes
bacteroides spp.
proteus, morganella, providencia
pseudomonas spp.
closteridium spp.
peptostreptococcus
fusobacterium: long gram neg rod, anaerobic

Actinomyces israelii gram stain/morph.

gram pos. branching filamentous rods
anaerobic
"molar tooth" colonies on agar, lumpy
may produce "sulfur granules" in pus which are dense clumps of organisms

Bacterial infection of the eye

conjunctivitis

chlamydia trachomatis

elementary body

N. gonorrheae
S. pneumoniae
H. influenzae, aegypticus

pink eye/conjunctivitis
X & V factor dependent

Bacterial infection of the ear: Otitis

moraxella catarrhalis

Moraxella catarrhalis gram stain/morph.

gram neg. coccobacillus, non-motile
"hockey puck" pitting of chocolate agar
"wagon wheel" colony morphology
oxidase pos.
catalase pos.
DNAse pos. (vs. Neisseria)

Sinusitis causes

h. influenzeae
strep pneumoniae
strep pyogenes

Diptheria

corynebacterium diptheria
"Klebs-Loeffler" bacillus
metachromatic, phosophate granules, "Bebes-Ernst" with methylene blue stain
chinese-letter morphology

C. diptheria on BAP

grayish colonies
may be slightly B-hemolytic
non-spore forming
non-branching
catalase pos.
non-motile

C. diptheria on CTBA

cysteine-tellurite blood agar

selective: potassium tellurite inhibits NF
differential: reduced tellurite is black/brown

bile esculin neg
grows well on Loeffler medium

Tox gene and C. diptheria

delivered by a bacteriophage
toxin producing strains cause tissue necrosis & formation of a pseudomembrane; can cause suffocation
tox fragment B binds to cell membranes > fragment A enters> stops protein synthesis
anti-tox + antibiotic

ELEK test

immunodiffusion
unk. organisms streaked at right angles to a paper strip impregnanted with diptheria antitoxin
as organism grows, if it produces a toxin, a line of precipitated antigen
(toxin) and antibody (antitoxin) forms

mycoplasma pneumoniae

"walking pneumonia"
growth on SP4 media (highly nutritious)
fried egg appearance
grainy
antibiotics added to inhibit faster growing contaminants
lack a cell wall

chlamydia(ophilia) pneumoniae

detection of cytoplasmic inclusion body using fluorescent-labeled monoclonal antibody
cultured in selected cell lines, no media

assay IgA/IgM antibody in symptomatic patients

chlamydia(ophilia) psittaci

Psittacosis
"parrot fever"
obligate intracellular
difficult & dangerous to grow
diagnosis by serologic testing, Aby titer to chlamydial antigens
round, elementary body inclusions

Legionnaire's Disease

legionella pneumophilia
acute illness with high fever, chills, chest pain, non-productive cough
gram negative bacillus
slow growth
"ground glass" colony appearance

L. pneumophilia on BCYE agar

buffered charcoal yeast agar with/without antibiotics
requires cystiene supplement
NG on BAP
fluoresce bright blue-white with UV

Whooping Cough

bordetella pertussis
gram neg coccobacillus
fastidious
bi-polar staining
Dx: serological, DFA, PCR
growth on Bordet Gengou agar (charcoal and horse blood)
BAP/MAC ng
metabolically inert

specimen collection in suspected bordetella infection

nasopharyngeal swab

Bordetella virulence factors

filamentous hemagglutinin

resembles fimbrae, allows it to stick and colonize the resp. epithelium

PTx (cell-bound pertussis toxin) - enhances its adherence to ciliated tracheal epithelium

as it degrades cilia,mucous begins to accumulate - results in coughing

Anthrax

bacillus anthracis
gram pos rods
blunt, square ends
central, oval endospores are refractile and don't stain
form chains
non-motile
catalase pos

B. anthracis

colonies flat, rough, gray, tenacious (tenacity test)
"beaten egg whites"
cat +, capsule +
mot -
"medusa" colony border

3 forms of B. anthracis

cutaneous -spores in cuts/bites --> black bile eschar
inhalation - severe
GI:nausea, vomiting

B. anthracis virulence factor, exotoxin

protective antigen (PA) allows edema factor (EF) and lethal factor (LF) to bind to receptors on the host cell
PA +EF = edema
PA + LF = cell death

Tuberculosis

mycobacterium tuberculosis
cell wall contains mycolic acid which prevents the organism from being stained with the routine gram stain
also protects the organism from phagocytosis, complement fixation

Mycobacterium sample processing

digestion and decontamination

sputum, yes
not used for sterile samples
liquifies and kills contaminating organisms

NaOH
N-acetyl-cysteine

centrifugation - high speed

Mycobacterium tuberculosis stain

acid fast stain:

carbofuchsin: primary stain; heat
decolorize with acid alcohol
counterstain with methylene blue
"beaded" appearance
non-motile
filamentous, branching

M. tuberculosis media

growth on Lowenstein-Jensen media

"buff, rough, tough"
37*C, 5-10%CO2, 2+weeks
malachite green is inhibitory
egg-based media

Middlebrook 7H11

agar-based
MTB exhibits "cording" of colonies

"Cording" of MTB on Middlebrook 7H11 media

virulent strains of m. tuberculosis, under certain conditions, grow as characteristic ropes, bundles, or serpentine cords known as cord factors or growth in cords

MTB niacin test

MTB lacks an enzyme that converts niacin to niacin ribonucleotide
niacin accumulates in media, reacts with cyanogen bromide --> yellow pigment
MTB is pos

MTB nitrate reduction test

tube method
organism incubated with sodium for 2 hours
Add HCl + sulfanilimide + N-naphthylenediamine dihydrochloride--> pink
if no color, add zinc dust
MTB is pos

MTB catalase type test

is the catalase stable after incubation at 68*C for 20 minutes?
most mycobacterium are catalase pos. at R.T.
MTB is pos even after heating at 68*C for 20 min
catalase reagent contains tween 80 (detergent) + 3% H2O2

Semi-quantitative catalase test

inoculate surface of L-J agar with broth subculture of the organism
incubate 2 weeks at 37C
Add 30% H2O2 and 10% tween
let stand 5min
measure the column of bubbles
<20 mm = neg
>45 mm = pos

Non-TB mycobacteria

photochromogens form pigment after exposure to light
scotochromogens form pigment in the dark vs nonphotochromogens

mycobacteria kansasii

causes chronic pulmonary disease; increased incidence in AIDS population

mycobacteria marinum

swimming pool granuloma

mycobacteria avia complex

most common cause of TB in the US

About this deck

By: Kelsey Johnson
Created: 2011-11-11
Size: 42 flashcards
Views: 2

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj