Bacterial Diseases

Vocabulary flashcards covering key bacteria, virulence factors, diagnostics, and treatments from the notes.

Gram Pos Cocci

staph aureus

staph epidermidis

strep pyogenes

Gram Pos Rods

cutibacterium acnes

bacillus anthracis

clostridium perfringens

Gram Neg Cocci

neisseria gonorrhoeae

Gram Neg Rods

eikenella corrodens

pasturella multocida

bartonella henslae

pseudomonas aeruginosa

vibro vulnificus

Reportable infections

anthrax

gonorrhea

lyme disease

spotted fever rickettsiosis

vibriosis

vancymycin intermediate/resistant staph aureus

Staphylococcus aureus biochemical properties

catalase positive

coagulase positive

ferments mannitol

Staphylococcus aureus reservoir

human only (nasopharynx and skin)

Staphylococcus aureus risk factors

hospitalization and healthcare settings

skin and soft tissue injury

Staphylococcus aureus skin infections

folliculitis

carbuncles and furuncles

cellulitis

scaled skin syndrome (infants)

impetigo

abscesses

Staphylococcus aureus MSK infections

top cause of septic arthritis

top cause of osteomyelitis

Staphylococcus aureus virulence factors

protein A

hemolysins, coagulase, catalase

pantone-valentine leucocidin

exfoliative toxin

MecA

mecA

alternative PBP that is resistant to beta-lactams

Beta Lactams

target PBPs that link proteins in cell wall

Exfoliative toxin

loss of cell to cell contact in skin epithelia

seen in scaled skin syndrome and impetigo

Panton-Valentine leukocidin (PVL)

causes leukocyte destruction and tissue necrosis

seen in CA-MRSA

Protein A

binds the Fc region of antibodies, preventing complement activation

Coagulase

converts fibrinogen to fibrin, encasing the bacteria in a clot to hide from the immune system

CA-MRSA

young, healthy, crowded setting, sports, skin trauma

HA-MRSA

hospital exposure, invasive devices, recent antibiotics

MSSA Treatment

cephalexin, cefazolin, nafcillin

MRSA Treatment

vancomycin

linezolid

Vancomycin MoA

binds peptidoglycan peptides and prevents synthesis

Linezolid MoA

binds ribosomes and stops protein synthesis

Staphylococcus epidermidis biochemical properties

catalase positive

coagulase-negative

mannitol fermentation negative

Staphylococcus epidermidis transmission

human only

endogenous spread

Staphylococcus epidermidis risk factors

foreign material or bodies (prosthetics, catheters)

Staphylococcus epidermidis infections

prosthetic joint or bone infections (artificial joints, orthopedic implants)

catheter infections

Staphylococcus epidermidis virulence factors

slime layer/glycocalyx formation

biofilms

Staphylococcus epidermidis treatment

cephalexin, cefazolin, nafcillin

Streptococcus pyogenes biochemical properties

Group A Streptococcus (lancet group A surface antigens)

beta-hemolytic

catalase negative

bacitracin sensitive

Streptococcus pyogenes transmission

respiratory droplets (pharyngitis)

direct contact (impetigo)

endogenous spread

Impetigo risk factors

contact with sores

Necrotizing fasciitis risk factors

diabetes, kidney disease, cirrhosis, cancer

Cellulitis risk factors

IV drug use, chronic skin conditions

Streptococcus pyogenes suppurative infections

scarlet fever

impetigo

erysipelas

cellulitis

necrotizing fasciitis

Streptococcus pyogenes suppurative infections

seen in patients not receiving antibiotic therapy

Scarlet Fever

strawberry tongue, sandpaper like rash, skin peeling, sore throat

Impetigo

honey colored crusted skin lesions

Toxic Shock Syndrome

Streptococcus pyogenes

fever, rash, skin peeling AFTER rash

Streptococcus pyogenes virulence factors

hyaluronic acid capsule

M protein

streptolysin O

pyogenic ectotoxin

Erysipelas

well defined skin rash

usually face or legs

bright red

Cellulitis

poorly defined borders, diffuse spread

Necrotizing Fasciitis

rapidly spreading

soft tissue infection with severe pain

Hyaluronic Acid Capsule

inhibits phagocytosis

M protein

inhibits complement activation

Streptolysin O

punches holes in membranes of RBCs and WBCs

Pyogenic exotoxin

superantigen

can cause scarlet fever or toxic shock

Streptococcus pyogenes treatment

most: amoxicillin

necrotizing fasciitis and toxic shock: penicillin G and clindamycin, possible debridement

Cutibacterium acnes characteristics

Gram-positive rod

anaerobic

no spores

Cutibacterium acnes reservoir

commensal in low levels on the skin

endogenous infection (sebum in follicles)

Cutibacterium acnes infections

ance vulgaris

surgical wounds

implant associated

Acne vulgaris

secretes digestive enzymes causing cellular damage, metabolic byproducts, and bacterial debris

triggers blackheads, whiteheads, pimples, oily skin, and scarring

Cutibacterium acnes surgical infections

abscesses, sinus tracts, osteomyelitis

in areas with many sebaceous glands

more common if prosthetic is involved

Cutibacterium acnes treatment

benzoyl peroxide

salicylic acid

retinoids

antibiotics

Bacillus anthracis characteristics

Gram-positive rod

spore-former

non-motile

non-hemolytic

unique capsule

Bacillus anthracis capsule

poly-d-gamma-glutamic acid

Bacillus anthracis reservoir

spores in environment

Bacillus anthracis cutaneous transmission

spore inoculated directly into skin and germinate

Bacillus anthracis epidemiology

zoonotic (herbivores)

Cutaneous Anthrax

painless black eschar only at inoculation site

massive edema

necrotic ulceration

Bacillus anthracis virulence factors

spores

protective antigen

lethal toxin (AB)

edema toxin (AB)

capsule

Anthrax Diagnosis

cutaneous dx based on clinical symptoms

culture and gram stain

PCR

Bacillus anthracis treatment

ciprofloxacin

doxycycline

Clostridium perfringens characteristics

Gram-positive rod

obligate anaerobe

forms spores

Clostridium perfringens transmission

spores enter wound or surgical site

Gas Gangrene Symptoms

bad vitals

crepitus

purple bullae

necrotic destruction of muscle

fast progression

Gas Gangrene Toxins

alpha toxin

beta toxin

hyaluronidase and collagenase

Clostridium perfringens diagnosis

double hemolysis

egg yolk agar

Clostridium perfringens prevention

clean wounds thoroughly

antibiotics before, during, and after abdominal surgery

Clostridium perfringens treatment

immediate: high dose penicillin, beta lactams, clindamycin

may need surgery or hyperbaric oxygen therapy

Neisseria gonorrhoeae characteristics

Gram-negative diplococci

oxidase positive

glucose fermenter

Neisseria gonorrhoeae transmission

human only

sexual contact or secretions

perinatal

Neisseria gonorrhoeae epidemiology

second most common STI

Disseminated Gonorrheal Infection

septic arthritis of joint (usually knee)

Neisseria gonorrhoeae virulence factors

pili for adherence and antigenic variation

Neisseria gonorrhoeae diagnosis

grows on chocolate agar and thayer martin agar

Neisseria gonorrhoeae treatment

ceftriaxone

HACEK group

fastidious, slow growing, gram neg organisms in the oral-pharyngeal flora

associated with poor dentition, periodontal disease, or oral trauma

Eikenella corrodens characteristics

Gram-negative short coccobacillus

non-motile

oxidase positive

microaerophilic

Eikenella corrodens diagnosis

chocolate agar

colonies smell like bleach

Eikenella corrodens transmission

commensal part of human oropharynx

transmitted through bites or fist fights

Eikenella corrodens risk factors

dental procedures

IV drug use

human bites

Eikenella corrodens treatment

amoxicillin/clavulanate

Pasturella multocida characteristics

Gram-negative coccobacillus

non-motile

growth on blood agar

oxidase positive

Pasturella multocida transmission

zoonotic (cats)

transmitted via cat bites

Pasturella multocida infections

rapid onset cellulitis

lymphadenopathy

necrotizing fasciitis, septic arthritis, osteomyelitis

Pasturella multocida cellulitis

rapid onset (within 24 hours)

pain, erythema, warmth, and swelling at bite site

purulent drainage or abscess

Pasturella multocida virulence factors

polysaccharide capsule

LPS

PMT toxin

Pasturella multocida diagnosis

culture

history of cat bite

Pasturella multocida treatment

beta lactam AND beta lactamase inhibitor

amoxicillin-clavulanate or ampicillin-sulbactam

Bartonella henselae characteristics

Gram-negative rod

fastidious

facultative intracellular

stains with silver stain or warthin-starry stain

Bartonella henselae transmission

zoonotic (cats)

bite, scratch, lick from infected cat

Bartonella henselae risk factors

interaction with cats

immunocompromised

Cat Scratch Fever

Bartonella henselae

papule or pustule at inoculation site

regional lymphadenopathy

Bacillary Angiomatosis

Bartonella henselae

occurs in immunocompromised

cranberry-like papule

Bartonella henselae virulence factors

Bad A protein

deformin

Cat Scratch Fever diagnosis

clinical symptoms

cat exposure

indirect immunofluorescent assay

Bacillary Angiomatosis diagnosis

warthin-starry silver staining

Bacillary Angiomatosis treatment

erythromycin or doxycycline

Cat Scratch Fever treatment

azithromycin IF immunocompromised