TABLE 2.

Characteristics of the 34 ceftazidime-resistant P. aeruginosa isolates

StrainjplCephalosporinase inhibition with CLO ata:MIC (μl/ml)bSp actc (mU/mg) [mean ± SD])βladTypeeType by RAPD analysisSite of recovery
250 μg/ml500 μg/mlTICTCCPIPTZPCAZFEPATMIPMMEM
17.8++1281281281281283264648730 ± 89NAg1Rectal swab
27.8++64646464321616168NDh12Wound
37.8+25625612812864326410.50.611 ± 2063Urines
47.8 + 5.4256641616128321281616PER-1114Rectal swab
58.0+25625625625664326410.515,373 ± 940NA5Rectal swab
68.0++646432163281610.251,566 ± 2266BPf
78.0+12812812812832321616161,602 ± 93117Wound
88.0++12812812812864323220.5321 ± 138Urine
98.0++64646432321616328231 ± 8119Urine
1018.0+12812812812864163210.51,679 ± 327610Rectal swab
118.0++12812812812812832128168124 ± 21NA11Rectal swab
128.0++2562562562566464640.51ND 1112Rectal swab
138.4+51251225625612864128241,010 ± 24NA13Blood
148.4+1281281281286432321681,243 ± 52614BP
158.4+256256256256128641288410,054 ± 30615BP
168.4++12812812812864323242688 ± 28116BP
178.4++12812812812864161620.5373 ± 12NA17BP
188.4 + 5.7+2,0481,0242562566432323216PSE-11218Rectal swab
198.4 + 5.7+2,048256256128321616324PSE-11219BP
208.4 + 7.0+256256643264321620.25OXA-21320PDFk
218.4 + 7.0+1281286464321616328OXA-21421BP
228.4 + 7.0+2562566464323232328OXA-21322BP
238.4 + 7.0+256256646464321620.25OXA-21423Urine
248.4 + 7.0+25625612812864323220.5OXA-21624Rectal swab
258.4 + 7.0+256256646464321620.25OXA-21325Blood
268.0 + 8.4++128128128128643232168894 ± 661126BP
278.0 + 8.4++1281281281286432320.51680 ± 801127BP
288.0 + 8.4++1281286464321616168693 ± 291128BP
298.0 + 8.4+25625612812864323210.5678 ± 9622BP
308.0 + 8.4++128128646412832128168177 ± 21NA29Rectal swab
318.0 + 8.4++6464646432832328641 ± 101130Wound
328.0 + 8.4++646464323281620.121,761 ± 50131Rectal swab
338.6++128128643264166410.2552 ± 1632Rectal swab
348.6+2562561281286464640.50.5ND 333BP
PAO18.0NAPiNAP≤16≤16≤4≤4≤22410.25<0.0011
  • a Cephalosporinase inhibition test on Mueller-Hinton agar with cloxacillin (CLO) at 250 or 500 μg/ml. +, ceftazidime zone diameter increase of >10 mm; −, ceftazidime zone diameter increase of ≤10 mm.

  • b Abbreviations: TIC, ticarcillin; TCC, ticarcillin-clavulanate (2 μg/ml); PIP, piperacillin; TZP, piperacillin-tazobactam (4 μg/ml); CAZ, ceftazidime; FEP, cefepime; ATM, aztreonam; IPM, imipenem; MEM, meropenem.

  • c AmpC activity was not determined for strains producing an additional β-lactamase.

  • d βla, additional β-lactamase.

  • e O serotype.

  • f BP, bronchopulmonary sample.

  • g NA, no agglutination.

  • h ND, not done.

  • i NAP, not applicable.

  • j The pairs of strains 10 and 24, 12 and 14, and 22 and 29 were each isolated from the same patient.

  • k PDF, peritoneal dialysis fluid.