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Gram-negative non-fermenting, motile bacillus; known for blue-green pus (pyocyanin and pyoverdin pigments)
Lab: culture of sputum, endotracheal aspirate, bronchoscopic specimens, urine, blood, abscess fluid, joint fluid, or CSF
Nonfastidious organism, can inhabit a variety of environments including soil and water (hot tubs, sinks, water faucets, respirators, disinfectants and contact lens cleaning solutions). Produces biofilm.
Drug resistance mechanisms: includes active efflux pumps, chromosomal and inducible beta-lactamases, plasmid-mediated ESBLs (TEM, SHV, CTX-M), and altered permeability. Loss of protein porin OprD results in resistance to carbapenems, specifically imipenem.
Nosocomial, opportunistic pathogen, especially in setting of immunocompromised host or foreign body (central line or urinary catheter).
Chronic colonizer of cystic fibrosis lung
Cause of pneumonia (ventilator-associated), UTI, bacteremia (neutropenia), post-neurosurgical meningitis, post-surgical infections, and hot-tub folliculitis
Cause of ecthyma gangrenosum: infarcted skin lesions, due to vascular invasion with heavy organism burden; uncommon and seen mostly in immune suppressed or critically ill patients
Risk factors include immunosuppression, DM, skin burns, cystic fibrosis and AIDS.
Multidrug resistance likely in those with recent abx therapy (past 90d),hospital stay > 4d, high rate of abx resistance in facility, residence in chronic care facility.
Historically associated with high mortality in febrile neutropenia (bacteremia, pneumonia and skin and soft tissue infections) and infected burn wounds (heavy bacterial growth in burn eschar).
- Respiratory: pneumonia (nosocomial, CF, AIDS) & lung abscesses
- GU: UTI/pyelonephritis (complicated by obstruction, manipulation, or foreign body)
- CV: endocarditis (IDU); bacteremia, line sepsis
- Skin: ecthyma gangrenosum (neutropenia); cellulitis (DM, IDU, post-operative); folliculitis; abscesses; noma neonatorum (gangrenous stomatitis)
- ENT: otitis externa, malignant otitis externa (DM); chronic otitis media; sinusitis (AIDS)
- CNS: brain abscesses; meningitis (post-neurosurgical)
- Bone/joint: vertebral, sternoclavicular or pelvic bone infections (IDU); osteochondritis of foot (following penetrating injuries through tennis shoes)
- Eye: keratitis, endophthalmitis
Prevention of nosocomial transmission with infection control: isolate infected pts, require hand-washing by staff & visitors.
In patients w/ chronic lung disease (e.g., CF), good pulmonary toilet (mucolytic agents, chest PT, postural drainage) are important adjunctive treatment measures.
In seriously ill, empiric treatment with concern for P. aeruginosa should use two active agents from two different classes. Once susceptibilities known, narrow to one drug according to susceptibility report.
Double coverage using high doses of synergistic antibiotic combinations (B-lactam + aminoglycoside) may improve outcomes of serious infections but remains controversial.
Multi-drug resistant strains may be susceptible to colistin or polymyxin B.
Pts with CF, pregnancy, burns, and critical illnesses may require higher doses of aminoglycosides. Monitor serum drug levels.
Use susceptibilities to guide final choices. Drugs that include activity against P. aeruginosa listed below but increasing resistance identified especially with ticarcillin, ciprofloxacin, levofloxacin.
Piperacillin 3g IV q4h or 4g IV q6h. Piperacillin/tazobactam offers no advantage for most isolated compared to piperacillin alone since most resistance is not beta-lactamase related.
Ticarcillin 3 IV q4h (increasing resistance seen)
- Cefepime 1-2g IV q8h
- or ceftazidime 2g IV q8h
- Imipenem 1g IV q6-8h;
- meropenem 1gm IV q8h;
- doripenem 500mg IV q8h
(carbapenemase-producing strains increasingly identified)
Ciprofloxacin 400mg IV q8h or 750mg PO q12h, increasing risk of resistance; would not use as empiric monotherapy
Aztreonam 2g IV q8h
- Gentamicin or tobramycin 3 mg/kg loading dose then 2 mg/kg IV q8h or 5-7 mg/kg IV every day or amikacin 8 mg/kg loading dose then 7.5mg/kg IV q12h. Monotherapy reserved for UTIs. Note: amikacin > tobramycin > gentamicin with respect to P. aeruginosa susceptibility percentages at most institutions. Irreversible
- vestibular and cochlear toxicity with greater cumulative dose and duration of tx.
Duration: uncomplicated UTI, 3-5d; urosepsis, 2 wks; pyelonephritis, 2-3 wks; pneumonia, >8-14d; bacteremia after removal of line, 7-10d; bacteremia with neutropenia, >14d or until neutrophil count recovered
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