Bugs and Drugs in CF Flashcards
CF is a risk factor for severe ______ infections of the lung as well as
gram negative
usually CF patients have multiple species in respiratory secretions
and MRSA (gram +)
predictable sequence of lung infections
H. influenzae → Staph aureus → Pseudomonas aeruginosa → Mucoid Pseudomonas → gram negative soup (end stage lung disease)
Pseudomomas aeruginosa
Burkholderia cepacia
Ralstonia spp
Stenotrophomonas spp
Achromobacter (formerly Alcaligenes) xylosoxidans
Etc.
May also get Mycobacteria and Aspergillus
old dogma - once colonized by a bug….
colonized forever or until a worse bug replaces it
new dogma - sometimes colonization can be (temporarily)…
cleared by aggressive treatment/abx
factors allowing bacterial persistence
- poor penetration of abx into purulent airway secretions
- resistance
- CF-related defects in mucosal defenses
- bacterial biofilms to render abx ineffective
staph aureus
Gram positive cocci
the most commonly found isolate in C.F.
often is Methicillin Resistant Staph aureus (MRSA)
Treatment
MSSA- Naficillin, Cefazolin, or Oxacillin
MRSA- Vancomycin, Septra, Clindamycin, Linezolid
BCC
burkholderia cepacia complex
Formerly classified as a Pseudomonas
Now is felt to actually be a complex of different genomovars
Usually far in progression of CF
“Cepacia Syndrome”: End stage lung function with fevers, weight loss, feeling bad
May be colonization or active infection
Usually highly resistant to many antibiotics
BCC associated with an accelerated decline in pulmonary function and shortened survival in CF
Infection with B. cenocepacia is considered to be a contraindication to transplantation in many centers.
contraindication for lung transplantation
B. cepacia infection
pseudomonas aeruginosa
aerobic gram - rod with flagella
catalase + and oxidase +
“smells like grapes or blue tortilla chips in the labs”
CF airways are conducive to growth
Increased bacterial binding to the epithelium
Decreased bacterial clearance via innate immune mechanisms
Prevalence increases with age
With prolonged infection, converts to a mucoid phenotype by the production of alginate. = worsens prognosis
what organism smells like grapes or blue tortilla chips?
pseudomonas aeruginosa
pseudomonas treatment
Pseudomonas is a smart bug– it can develop resistance to an antibiotic while actually receiving appropriate doses of the antibiotic
in CF, “double cover” Pseudomonas to help prevent resistance –>One antibiotic from two different classes with differing mechanisms of action
Using two drugs that work in the same manner is NOT double covering!!
Typically use an anti-pseudomonal penicillin or cephalosporin along with an aminoglycoside or a fluoroquinoline
Penicillins = Piperacillin-tazobactam, Ticarcillin-sulbactam
Cephalosporins = Ceftazadime, Cefepime
+
Aminoglycosides = Amikacin, Tobramycin, Gentamicin
Fluoroquinoline = Ciprofloxacin > Levofloxacin
drug for multi-drug resistant p aeruginosa
colistin
anti-pseudomonal drugs
Antipseudomonal penicillins (ticarcillin, piperacillin) -------Combination drugs of a penicillin plus beta-lactamase inhibitor (Piperacillin-Tazobactam, Ticarcillin-Sulbactam)
Third generation cephalosporins (ceftazadime)
Fourth generation cephalosporins (cefepime)
Monobactam (aztreonam)
Carbapenems (imipenem, meropenem)
Fluoroquinolones (ciprofloxacin and levofloxacin)
does double coverage work?
There is no proven evidence that two agents offer improved outcomes. However, there is no absolute proof it doesn’t help either
Another rationale for the use of combination therapy is to provide initial broad spectrum of activity when there is risk for multidrug resistant P. aeruginosa
cause of walking pneumonia?
mycoplasma
