Exam 1 - Gram Negative, Positive, & Atypical Bacteria

GRAM-POSITIVE BACTERIA — GENERAL

What stain color are Gram-positive bacteria?

Purple

What major cell-wall component is thick in Gram-positive bacteria?

Peptidoglycan

Do Gram-positive bacteria have an outer membrane?

No

Which bacterial structure is responsible for motility?

Flagella

Which bacterial structure is responsible for attachment?

Pili/fimbriae

Which bacterial structure can prevent phagocytosis?

Capsule

What bacterial process can pili participate in besides attachment?

Conjugation

GRAM-POSITIVE COCCI — STAPHYLOCOCCUS

What Gram status is Staphylococcus aureus?

Gram-positive

Is Staphylococcus aureus catalase-positive or catalase-negative?

Catalase-positive

Is Staphylococcus aureus coagulase-positive or coagulase-negative?

Coagulase-positive

Which Staphylococcus species is highly virulent?

Staphylococcus aureus

What enzyme causes plasma to clot and is produced by S. aureus?

Coagulase

What enzyme contributes to much S. aureus penicillin resistance?

Beta-lactamase

Which organism causes staphylococcal hypersensitivity from chronic blepharitis?

Staphylococcus aureus

Where are infiltrates located in staphylococcal hypersensitivity?

Near the corneal limbus

What ocular infections can Staphylococcus aureus cause?

Conjunctivitis, blepharitis, keratitis, and hordeola

What percentage of S. aureus is resistant to penicillin according to the guide?

90%

What Gram status is Staphylococcus epidermidis?

Gram-positive

Is Staphylococcus epidermidis catalase-positive or catalase-negative?

Catalase-positive

Is Staphylococcus epidermidis coagulase-positive or coagulase-negative?

Coagulase-negative

Which Staphylococcus is more prevalent but less pathogenic?

Staphylococcus epidermidis

Which organism is the most common cause of acute postoperative endophthalmitis?

Staphylococcus epidermidis

Which Staphylococcus is associated with adherence to medical devices?

Staphylococcus epidermidis

What does MRSE stand for?

Methicillin-resistant Staphylococcus epidermidis

What does VISE stand for?

Vancomycin-intermediate Staphylococcus epidermidis

GRAM-POSITIVE COCCI — STREPTOCOCCUS

What Gram status are Streptococcus species?

Gram-positive

Are Streptococcus species catalase-positive or catalase-negative?

Catalase-negative

What does hemolytic mean for Streptococcus?

Lysis of red blood cells

What group is Streptococcus pyogenes?

Group A Streptococcus

What hemolysis pattern does Streptococcus pyogenes have?

Beta hemolysis

Which Streptococcus is highly virulent?

Streptococcus pyogenes

What classic disease is caused by Group A Streptococcus?

Strep throat

What ocular infections can Streptococcus pyogenes cause?

Conjunctivitis, dacryocystitis, and central corneal ulcers

Where is Streptococcus pneumoniae normally found?

Nasopharyngeal flora

Which Streptococcus commonly causes otitis?

Streptococcus pneumoniae

Which Streptococcus has a bimodal distribution in children and the elderly?

Streptococcus pneumoniae

What ocular infections can Streptococcus pneumoniae cause?

Conjunctivitis and corneal ulcers

Which vaccine has decreased pneumococcal infections?

Pneumococcal vaccine

GRAM-POSITIVE RODS — CORYNEBACTERIUM

What Gram status is Corynebacterium?

Gram-positive

Is Corynebacterium catalase-positive or catalase-negative?

Catalase-positive

How is Corynebacterium disease commonly mediated?

Toxin-mediated

What selective agar is associated with Corynebacterium?

Tinsdale agar

What dye-based medium is associated with Corynebacterium?

Methylene blue

What encodes diphtheria toxin?

A bacteriophage

Is diphtheria toxin heat-labile or heat-stable?

Heat-labile

What eye finding can Corynebacterium diphtheriae produce?

Pseudomembranes

What ocular material can C. diphtheriae produce?

Thick gray adherent exudate

Can Corynebacterium diphtheriae invade an intact cornea?

Yes

What does DPT stand for?

Diphtheria, pertussis, and tetanus

GRAM-POSITIVE RODS — LISTERIA

What Gram status is Listeria?

Gram-positive

Is Listeria catalase-positive or catalase-negative?

Catalase-positive

What is the major transmission category of Listeria?

Foodborne

At what unusual temperature can Listeria grow?

Refrigerator temperatures

What organ system does Listeria have an affinity for?

The CNS

What pregnancy complication is associated with Listeria?

Miscarriage

What foods are associated with Listeria outbreaks?

Lettuce and cold cuts

Can Listeria invade an intact cornea?

Yes

How does Listeria behave inside host cells?

Like an intracellular parasite

GRAM-POSITIVE SPORE-FORMERS — BACILLUS

Which bacterial genus includes anthrax?

Bacillus

Which Bacillus species causes anthrax?

Bacillus anthracis

What is the most common form of anthrax?

Cutaneous anthrax

How does cutaneous anthrax usually enter the body?

Through a break in the skin

What is the respiratory form of anthrax called?

Wool Sorters Disease

How is respiratory anthrax acquired?

Inhalation of spores

What three components are included in the Bacillus exotoxin complex?

Edema factor, lethal toxin, and protective antigen

GRAM-POSITIVE SPORE-FORMERS — CLOSTRIDIUM

Which Clostridium causes gas gangrene?

Clostridium perfringens

Which Clostridium causes antibiotic-associated pseudomembranous colitis?

Clostridium difficile

Which Clostridium causes tetanus?

Clostridium tetani

Which Clostridium causes botulism?

Clostridium botulinum

What toxin causes tetanus?

Tetanospasmin

What is the major clinical effect of tetanospasmin?

Muscle spasms

What is the major clinical effect of botulinum toxin?

Paralysis

What type of lesion does C. difficile form?

Pseudomembranes

How does Clostridium perfringens commonly enter the body?

Through wounds

What treatment principle is essential for C. perfringens wound infection?

Debride dead tissue until healthy tissue is present

All of the following are gram positive bacteria, EXCEPT...Bordetella (delete)

Bordetella

GRAM-NEGATIVE BACTERIA — GENERAL

What stain color are Gram-negative bacteria?

Pink/red

Do Gram-negative bacteria have an outer membrane?

Yes

What component is associated with Gram-negative endotoxin?

LPS

What type of toxin is a secreted protein with specific effects?

Exotoxin

GRAM-NEGATIVE DIPLOCOCCI — NEISSERIA

What Gram status is Neisseria gonorrhoeae?

Gram-negative

What sugar does Neisseria gonorrhoeae ferment?

Glucose

What bacterial structures mediate N. gonorrhoeae adhesion?

Pili and outer membrane proteins

What type of infection is N. gonorrhoeae primarily associated with?

STI

What neonatal eye infection is caused by N. gonorrhoeae?

Ophthalmia neonatorum

Can N. gonorrhoeae invade an intact cornea?

Yes

What type of conjunctivitis is associated with N. gonorrhoeae?

Hyperacute conjunctivitis

Is topical therapy alone sufficient for gonococcal eye infection?

No

What major complication can gonococcal corneal ulcers cause?

Perforation and blindness

What Gram status is Neisseria meningitidis?

Gram-negative

What sugars does N. meningitidis ferment?

Glucose and maltose