Quick Review

Question 1

Legionnella

• Structure
• Symptoms
• Tests
• Trx

Answer 1

SS Cysteine Joins the Legion

• Gram negative bacilli
• Pneumonia (patchy with consolidation of one lobe) + Diarrhea + Hyponatremia (+ neuorlogical + fever)
• Test: culture requires charcoal yeast extract with cysteine and iron; rapid urine antigen test; oxidase positive//chest x-ray
• Trx: macrolides (azithromycin better than erythro); fluoroquinolones

Question 2

Strep pneumo

• Structure
• Symptoms
• Virulence fx
• Tests
• Trx

Answer 2

Alpha Knight Tournament, numero uno knight

• Gram positive, lancet-shaped diplococci, encapsulated
• MOPS: meningitis, otitis media, pneumonia, sinusitis; #1 cause of pneumonia (lobar, rusty sputum); splenectomy/sickle cell at greater risk
• Polysaccharide capsule; IgA protease
• Tests: Optochin sensitive, bile soluble, alpha-hemolytic
• Trx: ceftriaxone, macrolides, penicillin (but 20% resistance)

Question 3

Bordatella pertussis

• Structure
• Symptoms
• Virulence fx
• Tests
• Trx

Answer 3

Board and Room

• Gram negative, aerobic, nonfermentive, capsulated coccobacilli
• Whooping cough: 3 stages: catarrhal (rhinorrhea/mild cough; easy spread); paroxysmal (characteristic cough); convalescent (can last months)
• Pertussis toxin (ADP ribosylates Gi, increasing cAMP)
• Tests: Leukocytosis and cells that look like butts on a smear)
• Prevention: TDaP vaccine (tetanus, diptheria, acellular pertussis)
• Trx: anti-pertussis toxin Ig, erythromycin, TMP-SMX (for contacts); antibiotics don’t do much for outcomes bc, for dissemination purposes

Question 4

Corynebacterium diptheriae

• Structure
• Symptoms
• Virulence fx
• Tests
• Trx

Answer 4

• Gram positive bacilli, non spore forming, club-shaped
• Diphtheria: sore throat, fever, PSEUDOMEMBRANE covering oropharynx; can also damage heart and nervous tissue, sometimes skin lesions
• Exotoxin causes ADP ribosylates ELF2, causing protein synthesis failure and cell death
• Test: culture on tellurite and Loeffler’s media, Elek’s test for toxic vs. non-toxic, aniline dye stains red
• Trx: passive immunization (anti-toxoid)
• Vax: toxoid vaccine (inactivated exotoxin bound to protein)

Question 5

Pseudomonas

• Structure
• Symptoms
• Virulence fx
• Tests
• Trx

Answer 5

Pseudo Mona Lisa

• Gram negative rod
• # 1 cause of gram-negative nosocomial pneumonia, pulmonary infxn in DF patients (#1 cause of respiratory failure in CF), osteomyelitis in IV drug users and diabetics, burn pts., UTIs, skin lesions (hot tub folliculitis, ecthyma gangrenosum – necrotic lesions from sepsis), swimmer’s ear
• Exotoxin A – ribosylates EF-2 –> inhibits protein synthesis and cell death
• Complications: CGD puts pts. at risk
• Tests: oxidase positive, catalase positive, green pigment when plated from pyocyanin and pyoverdin
• Trx: fluoroquinolones (for UTIs), aminoglycosides, beta-lactam + beta-lactamase inhibitors (piperacillin + tazobactam; cephalosporin; carbapenems)

Question 6

Neisseria meningitidis

Answer 6

A Shocking Death on Campus

• Inflammatory response, capillary permeability, fluid leakage, hypovolemia, shock, meningitis, PETECHIAL RASH –> purpura, DIC (bleeding gums), Waterhouse-Friedrichsen syndrom (adrenal insufficiency from infarction)
• Chocolate agar, VPN agar, Oxidase positive, Maltose fermenting, Glucose fermenting
• Ceftriaxone, rifampin for close contacts

Question 7

Haemophilus influenzae

Answer 7

Phyllis’ Chocolate Covered Cherries

• Gram negative, coccobacilli
• Pneumonia
• EPIGLOTTITIS (cherry red epiglottis, drooling, stridor)
• Otitis media
• Meningitis: Type B capsular strain, there is a vaccine
• Sepsis and septic arthiritis, esp if asplenic and SCD
• Beta lactams, ceftriaxone, rifampin