Step 1 First Aid Exam questions with solutions

Step 1 First Aid , Microbiology




Bacterial Structures: Peptidoglycan - answerGives rigid support, protects against
osmotic pressure; Sugar backbone w/ cross-linked peptide side chains. (function;
chemical composition)

Bacterial Structures: Cell wall / cell membrane (G+'s) - answerMajor surface Ag;
Peptidoglycan for support. Teichoic acid induces TNF and IL-1. (function; chemical
composition)

Bacterial Structures: Outer membrane (G-) - answerSite of endotoxin (LPS), major
surface Ag; Lipid A induces TNF and IL-1 Polysaccharide is the Ag (function; chemical
composition)

Bacterial Structures: Plasma membrane - answerSite of oxidative and transport
enzymes; Lipoprotein bilayer (function; chemical composition)

Bacterial Structures: Ribosome - answerProtein synthesis; 50S and 30S subunits
(function; chemical composition)

Bacterial Structures: Periplasm - answerSpace btw the cytoplasmic membrane and the
outer membrane in G- bacteria; Contains may hydrolytic enzymes, including beta-
lactamases (function; chemical composition)

Bacterial Structures: Capsule Function? Structure? (... and exception?) -
answerProtects against phagocytosis; Polysaccharide (except in Bacillus anthracis ,
which contains D-glutamate) (function; chemical composition)

Bacterial Structures: Pilus/fimbria - answerMediate adherence of bacteria to cell
surface, sex pilus forms attachment btw 2 bacteria during conjugation; Glycoprotein
(function; chemical composition)

Bacterial Structures: Flagellum - answerMotility; Protein (function; chemical
composition)

,Bacterial Structures: Spore - answerProvides resistance to dehydration, heat, and
chemicals; Keratin-like coat, dipiclonic acid (function; chemical composition)

Bacterial Structures: Plasmid - answerContains a variety of genes for ABX resistance,
enzymes, toxins; DNA (function; chemical composition)

Bacterial Structures: Glycocalyx - answerMediates adherence to surfaces, especially
foreign surfaces (e.g. indwelling catheters); Polysaccharide (function; chemical
composition)

Structures unique to gram (+) organisms - answerTeichoic acid Cell wall <img
src="138b - cell wall.JPG" />

Structures common to Gram +/- organisms - answerFlagellum, pilus, capsule, PDG,
cytoplasmic membrane <img src="138a - cell walls.JPG" />

Features unique to G(-) organisms - answerEndotoxin/LPS (outer membrane)
Periplasmic space (location of many beta-lactamases) <img src="138c - cell wall gram
neg.JPG" />

Bacteria w/ unusual cell membranes/walls - answerMycoplasma: contain sterols and
have no cell wall Mycobacteria: Contain mycolic acid. High lipid content.

G(+) cocci - answerStaphylococcus Streptococcus

G(-) cocci - answerNeisseria

G(+) Rods - answerMy cobacterium (acid-fast) List eria B acillus C lostridium C
orynebacterium What happened when you were sending that email to Gram + Rod ? My
List B ecame CC 'd

My cobacterium (acid-fast) List eria B acillus C lostridium C orynebacterium What
happened when you were sending that email to Gram + Rod ? My List B ecame CC 'd -
answerG(+) Rods

G(-) Rods - answerH ave Y ou E ver L istened to GNR (Guns n' Roses = Gram (-)
Rods)? I like B oy B ands. B esides, Fran kly, I P refer Garden s to jungles.
Haemophilus Yersinia Enterics (separate card) Legionella (silver stain) Bordatella
Brucella Bartonella Francisella Pasteurella Gardnerella (gram variable)

H ave Y ou E ver L istened to GNR (Guns n' Roses = Gram (-) Rods)? I like B oy B
ands. B esides, Fran kly, I P refer Garden s to jungles. Haemophilus Yersinia Enterics
(separate card) Legionella (silver stain) Bordatella Brucella Bartonella Francisella
Pasteurella Gardnerella (gram variable) - answerG(-) Rods

Branching Filamentous bacteria (G+) - answerActinomyces Nocardia (weakly acid-fast)

,Actinomyces Nocardia (weakly acid-fast) - answerBranching Filamentous bacteria (G+)

Pleomorphic (G-) bacteria - answerRickettsiae Chlamydiae (Giemsa stain)

Rickettsiae Chlamydiae (Giemsa stain) - answerPleomorphic (G-) bacteria

Spirochetes (G-) - answerLeptospira Borrelia (Giemsa stain) Treponema

Leptospira Borrelia (Giemsa stain) Treponema - answerSpirochetes (G-)

Neither G+ nor G- (b/c no cell wall) - answerMycoplasma

Bugs that won't Gram stain - answerThese Rascals May Microscopically Lack Color
Treponema (too thin to be visualized) Rickettsia (intracellular parasite) Mycobacteria
(high-lipid-content cell wall requires acid-fast stain) Mycoplasma (no cell wall) Legionella
pneumophilia (primarily intracellular) Chlamydia (intracellular parasite; lacks muramic
acid cell wall)

Visualizing Treponemes - answerDarkfield microscopy and fluorescent Ab staining

Visualizing Mycobacteria - answerAcid-fast stain

Visualizing Legionella - answerSilver stain

Giemsa's stain is used to visualize...? - answeruse for: Borrelia Plasmodium
Trypanosomes Chlamydia

PAS (periodic acid-Schiff) stain - answerstains glycogen, mucopolysaccharides*; Used
to diagnose Whipple's dz (*PASs the sugar)

Ziehl-Neelsen stain - answerUse to stain Acid-fast bacteria

India ink - answerused to visualize Cryptococcus neoformans

Silver stain - answerused to visualize: fungi, Legionella

Media/Special culture requirements for: H. influenzae - answerChocolate agar w/ factors
V (NAD) and X (hematin) (Media used for isolation)

Chocolate agar w/ factors V (NAD) and X (hematin) - answerH. influenzae

Media/Special culture requirements for: N. gonorrheae - answerThayer-Martin media
(Chocolate agar based, w/ various ABX) (Media used for isolation)

Thayer-Martin media (Chocolate agar based, w/ various ABX) - answerN. gonorrheae

, Media/Special culture requirements for: B. pertussis - answerBordet-Gengou (potato)
agar (Media used for isolation)

Bordet-Gengou (potato) agar - answerB. pertussis

Media/Special culture requirements for: C. diphtheriae - answerTellurite plate, Loffler's
media (Media used for isolation)

Tellurite plate, Loffler's media - answerC. diphtheriae

Media/Special culture requirements for: M. tuberculosis - answerLowenstein-Jensen
agar (Media used for isolation)

Lowenstein-Jensen agar - answerM. tuberculosis

Media/Special culture requirements for: M. pneumoniae - answerEaton's agar (Media
used for isolation)

Eaton's agar - answerM. pneumoniae

Media/Special culture requirements for: E. coli - answerEosin-methylene Blue (EMB)
agar (blue-black colonies w/ metallic sheen) (Media used for isolation)

Eosin-methylene Blue (EMB) agar (blue-black colonies w/ metallic sheen) - answerE.
coli

Media/Special culture requirements for: Lactose-fermenting enterics - answerPink
colonies on MacConkey's agar (Media used for isolation)

Pink colonies on MacConkey's agar - answerLactose-fermenting enterics

Media/Special culture requirements for: Legionella - answerCharcoal yeast extract agar
buffered w/ increased iron and cysteine (Media used for isolation)

Charcoal yeast extract agar buffered w/ increased iron and cysteine - answerLegionella

Media/Special culture requirements for: Fungi - answerSabouraud's agar (Media used
for isolation)

Sabouraud's agar - answerFungi

G(-) Enterics (rod-shaped) - answerE. coli Shigella Salmonella Yersinia Klebsiella
Proteus Enterobacter Serratia Vibrio Campylobacter Helicobacter Pseudomonas
Bacteroides