Gram Negatives II Flashcards
What are the characteristics of Pseudomonas aeruginosa?
G- rod
Motile with flagella
Oxidase positive
Green fluorescent pigment pyoverdin
What are the Pseudomonas toxins?
Endotoxin (LPS) - fever, shock
Exotoxin A - inactivate elongation factor EF-2, necessary for protein synthesis
What are common Psuedomonas infections?
Pnemonia in CF
Burn infections
Hot tub folliculitis
Otitis externa (swimmer’s ear)
Osteomyelitis in IV drug users (classic case)
Ecthyma gangrenosum - black, necrotic ulcers
What is Pseuomonas folliculits?
Results form immersion in contaminated water
Secondary infection in people have acne or depilate their legs
What is the treatment for Pseudomonas?
Resistant to many antibiotics, treatment must be tailored
Combination: Anti-Pseudomonas penicillin plus an aminoglycoside
Why has multidrug resistance become a major issue with management of nosocomial P. aeruginosa infections?
Acquisition and accumulation of:
Chromosomal B-lactamases
Extended-spectrum B-lactamases (ESBL)
Porin channel mutations
Efflux pumps
What is Burkholderia cepacia?
G- rod
Oxidase and Catalase positive
Rare cause of two infections: CF, Chronic gramulotmatous disease
What is Legionella?
Doesn’t gram stain, use silver stain
BCYE agar, Fe and cyteine needed
What are the symptoms of Legionella infection?
Initially milde pneumonia symptoms - Fever, mild, slightly productive cough
GI - watery diarrhea, nausea, vomiting and abdominal pain
Hyponatremia
What is the classic presentation for Legionella?
Mild cough, Water diarrhea, confusion, G-
Treatment: Fluoroquinolone, Macrolide
What is Pontiac Fever?
Mild form of Legionella infection
Fever, malaise, chills, fatigue, headache
No respiratory complaints
What is Bacteroides fragilis?
G- rod
Most common bacteria in GI flora
Part of polymicrobial infections from GI tract
Treated with metronidazole
What is Acinetobacter?
Aerobic, G- bacteria that are widely distributed
Often multidrug resistant, occasionally cause nosocomial infection
What is Moraxella catarrhalis?
G- diplococci
Causes otitis media, COPD exacerbations
Usually treated empirically
What are some characteristics of Neisseria?
Cause meningitidis and Gonorrhea
G- cocci
Glucose fermenters
Ceftriaxone used to treat
What is the difference between N. meningococcus and N gonococcus?
N. meningococcus ferments maltose
Gonoccous only ferments glucose
What is the major virulence factor for Neisseria?
Polysaccharide capsule, basis for serotyping
What is the pathogenesis of meningococcus?
Adhere to nonciliated columnar epithelial and induce endocytosis
Avoids intracellular death and migrates to subepithelial space
May seed meninges and cause meningitis
What patients are at an increased risk for meningococcus infection?
Patients with late complement deficiencies (C5-C9)
What are the complications of bacteremia in N. meningitidis infection?
Spesis, fevers, chills, tachycardia
Pupuric rash
DIC
What is Waterhouse-Friderischsen syndrome?
Adrenal destruction from meningococcemia
What causes outbreaks in dorms/barracks and can infect young, healthy people?
N. meningitidis via respiratory droplets
What is the prophylaxis for N. meningitidis?
Rifampin
Ceftrixone or Ciprofloxacin
Describe N. meningitides vaccines?
Quadra-valent for group specific capsular polysaccharides
Does not cover sserotype B
Two vaccines:
MPSV4 - polysaccharide
MCV4 - conjugate to diptheria toxoid protein carrier
What are the characteristics of N. gonorrhea?
Mainly causes gonorrhea
Grown on Thayer-Martin agar
Key feature: antigenic variation of pilus proteins - no long term immunity, re-infection, no vaccine
What does N. gonorrhea co-infect with?
Chlamydia
Both cause same symptoms
What are the male and female symptoms of Gonorrhea?
Men: urethritis, dysuria, discharge. Can progress to epididymitits/orchitis
Women: Itching, discharge from cervix. Not painful, Can progress to PID
What is Pelvic Inflammatory Disease?
Infection by N. gonorrhea
Causes Pelvic/abdominal pain, dyspareunia, cervical motion tenderness (chandelier sign)
What is Fits-Hugh-Curtis Syndrome?
Infection by N. gonorrhea
Perihepatitis, inflammation of Glisson’s capsule around liver
Severe RUQ tenderness with pleuritic pain
Violin strain adesions of parietal peritoneum to liver
What is Bordetella Pertussis?
G- coccobacillus
Aerobic, oxidase and catalase +
Hallmark is lymphocytosis which prevents lymphocytes from entering lymph nodes
Grown on Bordet-Gengou media
Transmitted by aerosolized droplets
What are the symptoms of B. pertussis infection?
Recurrent, violent cough that can last up to 6 weeks
Capable of invading the respiratory trat causing pertussis or whooping cough
What is Pertussis toxin?
Shot to inhibit Gi protein
Increased cAMP levels in neutrophils
Causes impaired recruitment of neutrophils
May not cause cough
What is the vaccine for pertussis?
Administered in combination with toxoids of diphtheria and tetanus (DTaP)
Administration of doses at 2, 4, 6, and 15-18 months
Booster at 4-6 years
What is the treatment for B. pertussis?
Susceptible to several drugs
Main drug is erythromycin
