Micro - Clinical Bacteriology Flashcards
What are the two functions of the peptidoglycan layer in bacteria?
Rigid support and protection against osmotic damage
What is the chemical composition of the bacterial peptidoglycan layer?
A sugar backbone with cross-linked peptide side chains
What is the major surface antigen in gram-positive bacteria?
Cell wall
Which two cytokines does teichoic acid induce?
Tumor necrosis factor and interleukin-1
What structure in gram-negative bacteria induces tumor necrosis factor and interleukin-1?
The lipid A component of lipopolysaccharide
What is the major surface antigen in gram-negative bacteria?
Outer membrane (polysaccharide component of lipopolysaccharide)
Where is endotoxin (lipopolysaccharide) located in gram-negative bacteria?
In the outer membrane
Which bacterium has a nonpolysaccharide capsule?
Bacillus anthracis (which has D-glutamate)
_____ are bacterial structures that mediate adherence to the host cell surface and
are composed of glycoprotein.
Fimbriae (pili)
What bacterial structure establishes attachment between two bacteria during
conjugation?
Sex pili
_____ are bacterial structures that provide motility and are composed of protein.
Flagella
What bacterial structure provides resistance to desiccation, heat, and chemicals?
Spores
What is the chemical composition of a spore?
Keratin-like coat and dipicolinic acid
What kind of genetic information is stored in the bacterial plasmid?
Genes for antibiotic resistance, enzymes, and toxins
What structure aids bacteria in adhering to foreign objects, such as indwelling
catheters?
Glycocalyx
What is the chemical composition of glycocalyx?
Polysaccharide
What structures are common to both gram-positive and gram-negative bacteria?
Flagellum, pilus, capsule, peptidoglycan, and cytoplasmic membrane
What structure is unique to gram-positive organisms?
Teichoic acid
What structures are unique to gram-negative organisms?
Outer membrane (endotoxin/lipopolysaccharide)-lactamases in periplasmic space
What is between the capsule and peptidoglycan layers in gram-negative
organisms?
The outer membrane (which contains endotoxin/lipopolysaccharide)
What is the difference between the peptidoglycan layer of gram-positive organisms and that of gram-negative organisms?
The peptidoglycan layer in gram-positive bacteria is much thicker than that of gram-negative bacteria
What is between the inner cytoplasmic and outer membranes in gram-negative
organisms?
Periplasmic space (the location of many enzymes, including -lactamases)
Name the two major gram positive cocci.
Staphyloccus and Streptococcus
What are the major gram negative cocci?
Neisseria
Clostridium is a _____ (gram positive/gram negative) _____ (coccus/bacillus) .
Gram positive bacillus
Corynebacteriumis a _____ (gram positive/gram negative) _____
(coccus/bacillus).
Gram positive bacillus
Listeria is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram positive bacillus
What unique staining characteristic do Mycobacteriumand Nocardiapossess?
Mycobacterium and Nocardia are acid fast
Haemophilus is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus
Legionella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).
Gram negative bacillus
Bordatella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus
Yersinia is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus
Francisella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus
Brucella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).
Gram negative bacillus
Pasteurella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus
Bartonella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).
Gram negative bacillus
Gardnerella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).
Gram negative bacillus (gram staining can be variable)
What are the two types of gram positive branching, filamentous bacteria?
Actinomyces and Nocardia
Name three types of spirochetes.
Leptospira, Borrelia, Treponema
What type of bacteria contains sterols but lacks cell walls?
Mycoplasma
What type of bacteria contain mycolic acid in their cell walls and have high lipid
content?
Mycobacteria
Name six organisms that do not stain well by Gram stain.
Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella pneumophila,
and Chlamydia
Remember: These rascals may microscopically lack color
Name two methods used for visualizing treponemes.
Dark field microscopy and fluorescent antibody staining
Name three predominantly intracellular parasites that do not Gram stain well.
Rickettsia, Legionella, and Chlamydia
Mycobacteria can be visualized by acid-fast stain as a result of what characteristic?
High lipid content in the cell wall
What is the reason that Mycoplasma do not Gram stain?
It does not have a cell wall
Which primarily intracellular organism does not Gram stain well but can be seen
with silver stain?
Legionella pneumophilia
Borrelia, Plasmodium, Trypanosoma, and Chlamydiaspecies can be visualized
using what type of stain?
Giemsa stain
Periodic acid-Schiff (PAS) staining is used to stain what types of metabolic
substances?
Glycogen and mucopolysaccharides (PASs the sugar)
True or False: Periodic acid-Schiff staining is used to diagnose Whipples disease.
True
Ziehl-Neelsen stain is used to stain what organisms?
Acid-fast bacteria
India ink and mucicarmine can be used to visualize what pathogen?
Cryptococcus neoformans
Silver stain is used to stain what organisms?
Pneumocystis and Legionella
Haemophilus influenzae requires what medium to grow?
Chocolate agar with factors V (NAD) and X (hematin)
Neisseria gonorrhoeae requires what medium to grow?
Thayer-Martin (VPN) media
Bordetella pertussis requires what medium to grow?
Bordet-Gengou (potato) agar
Which media are used to culture Corynebacterium diphtheriae?
Tellurite plate, Loefflers medium
Mycobacterium tuberculosis requires what medium to grow?
L&wenstein-Jensen agar
Lactose-fermenting enterics on MacConkeys agar grow colonies that are what
color?
Pink
Legionella requires what medium to grow?
Charcoal yeast extract agar buffered with cysteine
Fungi require what medium to grow?
Sabourauds agar
In what medium can Mycoplasma pneumoniae grow?
Eatons agar
Escherichia colic an grow on what medium other than MacConkeys agar?
Eosin-methylene blue agar
What is the appearance of Escherichia coliwhen it is grown on eosin-methylene
blue agar?
Colonies with blue-black color and metallic sheen