Some of the toxins produced by Pseudomonas aeruginosa

Some of the toxins produced by Pseudomonas aeruginosa Name Activity Elastase Breakdown of elastin Proteases Breakdown of proteins Phospholipase C Hemolysis; breakdown of surfactant Exotoxin A Dermonecrosis; cell necrosis Lipid A Endotoxin

Selected predisposing factors and types of Pseudomonas infection - 1 Predisposing factor Type of infection Early age Septicemia, meningitis, enteritis Diabetes Malignant otitis externa Burns Burn wound infection, septicemia Trauma Osteomyelitis Drug abuse Endocarditis, septic arthritis, osteomyel. Cystic fibrosis Pneumonia, chronic or recurrent Neutropenia Septicemia, pneumonia, abscesses

Selected predisposing factors and types of Pseudomonas infection - 2 Predisposing factor Type of infection Neurosurgerical operations Meningitis Surgical operations Pneumonia Tracheostomy Pneumonia Intravenous lines Cellulitis, suppurative thrombophlebitis Corneal injury Panophtalmitis Kidney stones Urinary tract infection Catheterization Urinary tract colonization and infection

Outpatients Inpatients ICUs

Resistance % in P. aeruginosa

P. aeruginosa isolates from ICU patients USA - 1993 -2002 30 1 drug 2 drugs† 25 ≥ 3 drugs† 20 15 10 5 0 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 †P<0. 05 Obritsch et al. Antimicrob Agents Chemother 2004; 48: 4606

Frequency of MDR P. aeruginosa 10% 8% 8. 2 6% 4. 7 4% 1. 6 2% 1. 2 0% Latin America Europe Asia-Pacific United States J. Vila, 2007

Intrinsic (natural) resistance in P. aeruginosa is mainly due to the interplay between the outer membrane barrier and constitutive expression of an efflux pump

OMF PPP MFP OMF Pump Protein Proper Membrane Fusion Protein Outer Membrane Factor OMF MFP PPP Possible structure of an efflux system (Nikaido, 1994)

P. aeruginosa – mechanisms of acquired resistance Mutational β-lactams (carbapenems? ) fluoroquinolones Gyr. AB/Par. CE mutations in QRDRs Amp. C β-lactamase overexpression Mutations leading to aminoarabinose addition to lipid A (pmr. AB, others) colistin Opr. D porin loss Mex efflux pumps carbapenems β-lactams (IPM? ) fluoroquinolones aminosides Courtesy G. M. Rossolini

P. aeruginosa – mechanisms of acquired resistance Mutational β-lactams fluoroquinolones Gyr. AB/Par. CE mutations in QRDRs Amp. C β-lactamase overexpression Mutations leading to aminoarabinose addition to lipid A (pmr. AB, others) colistin Opr. D porin loss Mex efflux pumps carbapenems β-lactams fluoroquinolones aminosides Courtesy G. M. Rossolini

n Ceftazidime n Cefotaxime n Cefepime E. coli E. cloacae P. aeruginosa Rates of cephalosporins permeation through porin channels (Nikaido et al. , 1990)

Quinn et al. , 1988 Resistance to carbapenems in Pseudomonas aeruginosa was associated with the loss of the 46 -48 k. DA outer-membrane protein D 2, subsequently renamed Opr. D.

V ( nmol / min / mg ) 3 -C (Opr. D+) 100 l l l 50 l l l 3 -B (Opr. D-) l 0 l lll 0 1 2 m. M Rates of imipenem hydrolysis in Pseudomonas aeruginosa (Trias et al. , 1989)

However, in Opr. D-deficient strains, selection of derepressed mutants hyperproducing Amp. C-type chromosomal beta-lactamases (Ambler class C) significantly contributes to imipenem resistance. Moreover, a decrease in Opr. D expression regularly accompanies overexpression of the multidrug efflux system Mex. EF-Opr. N.

2008 Carbapenem-resistant Pseudomonas aeruginosa

P. aeruginosa – mechanisms of acquired resistance Mutational β-lactams fluoroquinolones Gyr. AB/Par. CE mutations in QRDRs Amp. C β-lactamase overexpression Mutations leading to aminoarabinose addition to lipid A (pmr. AB, others) colistin Opr. D porin loss Mex efflux pumps carbapenems β-lactams fluoroquinolones aminosides Courtesy G. M. Rossolini

-lactams and Amp. C phenotypes Hydrolyzed Inducer Phenotype Aminopenillins, cephamycins + + Carbapenems - + Susceptible Antipseudomonal penicillins and cephalosporins + - Susceptible, but. . Resistance can be induced by inducers It can be acquired during therapy with selection of Amp. C derepressed mutants Intrinsic resistance

2008 Ceftazidime-resistant Pseudomonas aeruginosa

P. aeruginosa – mechanisms of acquired resistance Mutational β-lactams fluoroquinolones Gyr. AB/Par. CE mutations in QRDRs Amp. C β-lactamase overexpression Mutations leading to aminoarabinose addition to lipid A (pmr. AB, others) colistin Opr. D porin loss Mex efflux pumps carbapenems β-lactams fluoroquinolones aminosides Courtesy G. M. Rossolini

2008 Fluoroquinolone-resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa can easily become resistant not only by mutation but also by acquisition of genetic elements such as plasmids, transposons and integrons.

Acquired R genes aminosides (all) r. RNA methylases (Rmt. A) β-lactams (variable) β-lactamases - narrow-spectrum (e. g. PSE / OXA) - extended-spectrum (e. g. PER / VEB/ OXA) - metallo-enzymes (IMP / VIM) aminosides (variable) AG-modifying enzymes [e. g. AAC(6’)-I; ANT(2”)-I] Resistance integrons mobile gene cassettes Courtesy G. M. Rossolini

2008 Aminoglycoside-resistant Pseudomonas aeruginosa

Acquired R genes aminosides (all) r. RNA methylases (Rmt. A) β-lactams (variable) β-lactamases - narrow-spectrum (e. g. PSE / OXA) - extended-spectrum (e. g. PER / VEB/ OXA) - metallo-enzymes (IMP / VIM) aminosides (variable) AG-modifying enzymes [e. g. AAC(6’)-I; ANT(2”)-I] Resistance integrons Courtesy G. M. Rossolini