249. Silent Dissemination of KPC producing- Klebsiella spp. with ESBL phenotype
Session: Poster Abstract Session: Diagnostic Microbiology; Antimicrobial Sensitivities
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • Silent Dissemination of KPC producing- Klebsiella spp. with ESBL phenotype.pdf (1.3 MB)
  • Background: KPC β-lactamase usually confers resistance to β-lactam antibiotics, however, the presence of blaKPC may cause MIC increase to carbapenems that remain within the susceptible (S) or intermediate (I) range, making its detection a challenge for the microbiology lab. The role of undetected KPC-harboring isolates in the clinical outcome of patients with infections by carbapenem-S microorganisms remains unknown.  Here we present the molecular characterization of KPC-harboring Klebsiellaspp. ESBL (+) isolates with low MICs for most cephalosporins and all carbapenems.

    Methods: Between Feb – Apr 2013, 6 isolates (K. pneumoniae (Kpn), n=3; K. oxytoca (Kox), n= 3) from 3 hospitals located in 2 Colombian cities, belonging to our Healthcare Associated Infections and Bacterial Resistance Surveillance Network, were received at CIDEIM. Isolates had an unusual phenotype: ESBL (+), S to most cephalosporins and carbapenenems according to CLSI 2012 breakpoints. Phenotypic characterization was performed by Vitek2, broth microdilution (BMD)/ E-test/ Kirby-Bauer; and modified Hodge test (MHT), double disk ESBL test (DD) and inhibition with phenylboronic acid (DD/BA). PCR was used to detect blaKPC blaSHV, blaTEM, blaCTX-M, blaVIM, blaIMP followed by sequencing in positive strains. Expression of blaKPC was assessed by qRT-PCR, using rpoDas normalizing gene. Genetic relatedness was evaluated by PFGE.

    Results: MIC for cephalosporins ranged from ≤1 – 4 ug/mL, for 5/6 isolates, whereas for carbapenems all isolates were confirmed to be in the S/I range (MICs =0.25-2 ug/mL). DD ESBL test was (+) for all isolates, however, only one was confirmed as true ESBL(+) by DD/BA. All isolates were MHT (+) and all were confirmed to harbor KPC-2. PFGE showed that Kpn isolates were not related, while 2/3 Kox were clonally related. 2/6 KPC(+) isolates co-harbored SHV-1 and the true ESBL(+) isolate harbored SHV-11/TEM-1. All isolates were shown to express blaKPCat low levels, compared to a high MIC control strain.

    Conclusion: In a KPC- endemic country like Colombia the silent dissemination of isolates harboring KPC is of great concern as it may give false ESBL(+)  test results and unusual phenotypes misleading to an inappropriate therapeutic choice and silent outbreaks.

    Laura J. Rojas, MSc1, Elsa De la Cadena, BS1, Gabriel Motoa, MD1, Adriana Correa, MSc1, Paola Rojas, MD2, Walter Zea, BSc2, Fernando Rosso, MD3, Claudia Castañeda, MSc3, Martin Muñoz, MD4, Maria Díaz, BSc4, John Quinn, MD5 and Maria V. Villegas, MD, MSc1, (1)Centro Internacional De Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia, (2)Hospital General de Medellin, Medellin, Colombia, (3)Fundación Clínica Valle del Lili, Cali, Colombia, (4)Centro Médico Imbanaco, Cali, Colombia, (5)AstraZeneca, Waltham, MA

    Disclosures:

    L. J. Rojas, None

    E. De la Cadena, None

    G. Motoa, None

    A. Correa, None

    P. Rojas, None

    W. Zea, None

    F. Rosso, None

    C. Castañeda, None

    M. Muñoz, None

    M. Díaz, None

    J. Quinn, AstraZeneca: Employee, Salary

    M. V. Villegas, MSD: Consultant, Research support
    AstraZeneca: Consultant, Research support
    Pfizer: Consultant, Research support
    Merck SA Colombia: Consultant, Research support
    Novartis: Consultant, Research support

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.