Author(s)

Jen-Jain Lee^1*, Yi-Ching Huang^2,3*, Yuting Hsiao^1,4, Chi-Han Lee⁵, Chuan-Shee Liu¹, Chishih Chu⁵

¹Medical Laboratory Division, Chiayi Branch, Taichung Veterans General Hospital, Taichung.
²Division of Infectious Diseases, Chiayi Branch, Taichung Veterans General Hospital, Taichung.
³Jen-Ai Hospital-Dali Branch, Taichung.
⁴Yuan’s General Hospital, Kaohsiung.
⁵Department of Microbiology, Immunology, and Biopharmaceutics, National Chiayi University, Chiayi.

Extended-spectrum β-lactamases (ESBLs) and/or AmpC enzymes combined with deficiency of porins OmpK35 and OmpK36 are important for the development of carbapenem-resistant Klebsiella pneumoniae. We characterized the clinical K. pneumoniae human isolates and investigated the effect of meropenem induction on the ompK35 and ompK36 mutation to develop carbapenem resistance from six carbapenem-susceptible ESBL-producing K. pneumoniae strains. 163 clinical K. pneumoniae isolates were grouped mostly into the ESBL + AmpC (44.2%) and ESBL (42.9%) phenotypes. The resistance rate differed between cephalosporins (52.1% for cefepime - 97.5% for cefotaxime) and carbapenems (16% for meropenem - 28.2% for imipenem) (P < 0.001). The ESBL group showed the lowest resistance to cefoxitin and cefepime and all carbapenems, whereas the AmpC group exhibited the lowest resistance to cefepime and the highest resistance to all carbapenems. PCR amplification identified bla_TEM, bla_SHV, bla_CTX-M-3-like, and bla_{CTX-M-14-like} of AmpA β-lactamase genes and bla_DHA and bla_CMY of AmpC β-lactamase genes. Compared to all 163 clinical isolates, the 56 carbapenem-resistant isolates carried less frequently of bla_TEM, bla_CTXM-14-like, and bla_CTXM-3-like and more frequently of bla_DHA-1 and bla_CMY-2. The carbapenem-resistant isolates differed in prevalence against imipenem, ertapenem, and meropenem and lacked OmpK35 more frequently than OmpK36, but abnormal PCR amplicons were detected fewer in the Omp K35-deficient group than in the OmpK36-deficient group (32.5% vs. 68.4%, respectively). The carbapenem-resistant isolate mostly carried bla_DHA (91.1%) and three isolates carried bla_KPC-2. Following induction with meropenem insertion sequences in ompK36, not ompK36, were identified as IS5 for KP08, IS1 for KP15, and IS903 for KP16 isolates. OmpK36 deficiency increased resistance to ertapenem, but not imipenem and meropenem. Clinical isolates belonged mainly to ESBL + AmpC group and ESBL group with difference in resistance to cephalosporins and carbapenems, the bla genes. Carbapenem resistant isolates lacked OmpK35 expression, than the OmpK36 expression, Meropenem induction developed the carbapenem resistant isolates with insertion of different insertion sequences in ompK36, not ompK35.

Klebsiella Pneumoniae , Carbapenem, ESBL, AmpC, Outer-Membrane Protein, Insertion Sequences

Lee, J. , Huang, Y. , Hsiao, Y. , Lee, C. , Liu, C. and Chu, C. (2018) Insertion Sequence-Dependent OmpK36 Mutation Associated Ertapenem Resistance in Clinical Klebsiella pneumoniae. Advances in Microbiology, 8, 253-269. doi: 10.4236/aim.2018.84017.