TABLE 2.

Correlation of resistance phenotypes and mechanisms relevant for resistance to ureidopenicillins and cephalosporins, carbapenems, aminoglycosides, and quinolones for 22 multiresistant P. aeruginosa strainsa

StrainMIC (mg/liter) for:Result for indicated resistance mechanism
Ureidopenicillins and cephalosporinsCarbapenemsAminoglycosidesQuinolonesEffluxOprD statusType II topoisomeraseAmpC overproductionAcquired resistance gene(s)
PiperacillinPiperacillin-tazobactamCeftazidimeCefepimeImipenemMeropenemGentamicinTobramycinAmikacinCiprofloxacinLevofloxacinEPI testMexR, NalC (MexAB-OprM)NfxB (MexCD-OprJ)MexT (MexEF-OprN)MexS (MexEF-OprN)MexZ (MexXY-OprM)GyrAParC
From CF patients
    I128128>32>323281623248+LossThr83Ile+
    II>128>128>32>32328324>3224++LossNA
    III>128>128>32>32328328>3248+LossAsp87Asn+
    IV>128>128>32>32816>3232>3224+LossAsp87AsnNA
    V>128>128>32>321616>328>3248+++LossThr83IleNA
    VI6432323284>324>3248Intact+NMThr83Ile+
    VIab+Loss
    VII>128>128>32>3216161623288+Intact++NMThr83Val+
    VIIacThr83Ala
    VIII643283284162>32816NA+LossThr83Ile
    IX>128>128>32>32>323216432>8128+LossThr83Ile+
    X>128>128>323216441844+LossThr83Ile+
    XI12812832321681621624+LossAsp87Asn+
    XII>128128>32321644432>816+++LossThr83Ile+
From non-CF patients
    XIII>128>128>32>323216328>3248+LossThr83Ile+
    XIV>128>128>32>32>3232162>3248+LossThr83Ile+
    XV643216>323216>32>32>32>832+LossThr83Ile+
    XVI64323216168>32168>832+LossThr83IleSer80Leuaac(6′)Ib
    XVII6432>32>323216>32>3216>816+LossThr83Ile+aadA1, aadB, aphA1-IAB
    XVIII3216161616163216>32>8128++ (MexR)+LossThr83Ile Asp87HisSer80Leu+aacA7, aacA8, blaOXA-2
    XIX>128>12832>323216161632>816IntactNMThr83IleSer80Leu+aac(6′)Ib, aadA2, blaPSE-1
    XX>128>128>32>32168>321616>832++ (MexR)+LossThr83Ile+aac(6′)Ib′, aadA2
    XXI3232168428216>8128++ (MexR)IntactNMThr83Ile Asp87GlySer80Leu
    XXII32321616161621828++ (NalC)++Loss
    PAO1442220.520.540.130.5
  • a Variants of strains are listed only for cases in which divergent results for resistance mechanisms were obtained. NA, no analysis possible; NM, no modification; +, positive test result or detection of resistance-relevant modification(s); −, negative test result or no detection of resistance-relevant modification(s) or acquired genes.

  • b Variant of clone VI.

  • c Variant of clone VII.