Table 4 The relation between the 2 anti P. aeruginosa β-lactamines capable of generating a mutation (ceftazidime and meropenem) and the different acquired resistance mechanisms

Impermeability

no/yes

108 (94.7%) / 6 (5.3%)

38 (97.4%) / 1 (2.6%)

0.679

93 (98.9%) / 1 (1.1%)

53 (89.8%) / 6 (10.2%)

0.0135*

Over-expression of efflux

no/yes

108 (94.7%) / 6 (5.3%)

37 (94.9%) / 2 (5.1%)

0.999

92 (97.9%) / 2 (2.1%)

53 (89.8%) / 6 (10.2%)

0.055

Penicillinase and/or efflux

no/yes

111 (97.4%) / 3 (2.6%)

38 (97.4%) / 1 (2.6%)

0.999

92 (97.9%) / 2 (2.1%)

57 (96.6%) / 2 (3.4%)

0.640

AmpC over-expression

no/yes

105 (92.1%) / 9 (7.9%)

30 (76.9%) / 9 (23.1%)

0.019*

84 (89.4%) / 10 (10.6%)

51 (86.4%) / 8 (13.6%)

0.613

Impermeability +/- Over-production of efflux

no/yes

113 (99.1%) / 1 (0.9%)

37 (94.9%) / 2 (5.1%)

0.160

93 (98.9%) / 1 (1.1%)

57 (96.6%) / 2 (3.4%)

0.559