Phenotypic and molecular characteristics of the MDR Enterobacteriaceae isolates detected in the screening cultures during the 18-month hospitalization of the patient

Antibiotic tested or isolate characteristicMIC [µg/ml (interpretationb)] or other characteristic(s) of indicated isolate from indicated sample
Urine (March 2012h): E. coli (Ec-38)Nasopharyngeal swab (March 2012)Perianal swab (March 2012)Perianal swab (May 2012 [August 2013])a
C. koseri (Ck-39)K. pneumoniae (Kp-39-1)K. pneumoniae (Kp-39-2)C. koseri (Ck-41)K. pneumoniae (Kp-41)K. pneumoniae (Kp-43)S. Kentucky (Sk-1 [and Sk-2])
Piperacillin-tazobactam32 (R)64 (R)≥128 (R)16 (I)32 (R)16 (I)32 (R)≥128 (R)
Ticarcillin-clavulanate128 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)
Cefoxitin8 (NA)8 (NA)32 (NA)8 (NA)16 (NA)8 (NA)8 (NA)8 (NA)
Ceftriaxone≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)≥256 (R)64 (R)
Cefotaxime≥128 (R)≥128 (R)≥128 (R)≥128 (R)≥128 (R)64 (R)≥128 (R)64 (R)
Cefotaxime-clavulanate≤0.064 (NA)4 (NA)8 (NA)4 (NA)8 (NA)8 (NA)4 (NA)16 (NA)
Ceftazidime16 (R)32 (R)128 (R)64 (R)64 (R)64 (R)128 (R)≥256 (R)
Ceftazidime-clavulanate0.25 (NA)8 (NA)8 (NA)8 (NA)8 (NA)8 (NA)8 (NA)≥256 (NA)
Cefepime≥32 (R)16 (R)≥32 (R)16 (R)16 (R)16 (R)16 (R)≥32 (R)
Aztreonam≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)
Imipenem≤0.25 (S)≤0.25 (S)≤0.25 (S)≤0.25 (S)≤0.25 (S)≤0.25 (S)≤0.25 (S)≤0.25 (S)
Meropenem≤0.5 (S)≤0.5 (S)≤0.5 (S)≤0.5 (S)≤0.5 (S)≤0.5 (S)≤0.5 (S)≤0.5 (S)
Ertapenem≤0.125 (S)0.5 (S)2 (R)≤0.125 (S)≤0.125 (S)≤0.125 (S)≤0.125 (S)1 (I)
Doripenem≤0.064 (S)≤0.064 (S)0.25 (S)≤0.064 (S)≤0.064 (S)≤0.064 (S)≤0.064 (S)0.25 (S)
Gentamicin≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≥32 (R)≤0.5 (S)
Tobramycin≥16 (R)≥16 (R)≥16 (R)≥16 (R)≥16 (R)≥16 (R)≥16 (R)≥16 (R)
Amikacin≥64 (R)8 (S)8 (S)8 (S)4 (S)≤2 (S)≤2 (S)8 (S)
Ciprofloxacin≥4 (R)≥4 (R)≥4 (R)≥4 (R)≥4 (R)2 (R)2 (R)≥4 (R)
Trimethoprim-sulfamethoxazole≥8 (R)≥8 (R)≥8 (R)≥8 (R)≥8 (R)≥8 (R)≥8 (R)≤0.25 (S)
Colistin≤0.125 (S)≤0.125 (S)≤0.125 (S)≥8 (R)c≤0.125 (S)≤0.125 (S)≤0.125 (S)≤0.125 (S)
Polymyxin B≤0.125 (NA)≤0.125 (NA)0.5 (NA)≥8 (NA)≤0.125 (NA)0.5 (NA)0.5 (NA)0.5 (NA)
Doxycycline≤1 (NA)≥32 (NA)≥32 (NA)≥32 (NA)≥32 (NA)≥32 (NA)≥32 (NA)≤1 (NA)
Tigecycline≤0.125 (S)0.5 (S)0.5 (S)≤0.125 (S)0.5 (S)≤0.125 (S)≤0.125 (S)≤0.125 (S)
bla genesCTX-M-15CTX-M-15CTX-M-15CTX-M-15CTX-M-15CTX-M-15CTX-M-15OXA-48
Plasmid incompatibility group(s)fF, FII, Nt-1Nt-2Nt-1, Nt-2F, Nt-2Nt-2F, Nt-2F, Nt-2L/M
aIEF, isoelectric points ±0.2g8.9, 7.6, 5.49.1, 8.9, 7.6, 5.48.9, 7.8, 7.6, 6.8, 5.48.9, 7.6, 5.48.9, 7.6, 5.48.9, 7.6, 5.48.9, 7.6, 5.48.0, 7.6, 7.2, 6.3
  • a Another perianal swab collected in August 2013 was positive for an MDR Salmonella Kentucky strain with the same phenotypic and molecular characteristics.

  • b According to EUCAST criteria (11); R, resistant; I, intermediate; S, susceptible; NA, not applicable or not available. MICs were obtained by implementing the ESB1F and GNX2F plates (Trek Diagnostics).

  • c The MIC for colistin was also elevated (4 μg/ml) when measured by Etest (bioMérieux).

  • d No TEM- or SHV-type ESBLs were present. For K. pneumoniae, SHV-1-like indicates the natural β-lactamases.

  • e Salmonella Kentucky was also positive for the following antibiotic resistance genes: aac(6)-Ib, tet(A), sul1, and mphA. Amino acid substitutions in GyrA (Ser83Phe and Asp87Asn) and ParC (Ser80Ile) were also found.

  • f Nt-1, nontypeable plasmid PCR positive only for replicon R; Nt-2, nontypeable plasmid PCR positive only for replicon FIB-M.

  • g pI of ∼8.9, CTX-M-15; pI of ∼9, CMY-4; pI of ∼5.4, TEM-1-like; pI of ∼7.6, SHV-1-like; pI of ∼7.4, VEB-8; pI of ∼7.2, OXA-48 (

  • h Date of isolation.