A 17-day-old newborn with no perinatal history to be highlighted.
Eleven days after admission to the ICU for RSV bronchiolitis, she developed fever, phlebitis in one arm through a peripheral venous line, and painful swelling, with redness and heat in the second joint.
Empirical antibacterial treatment with meropenem 60 mg/kg/day and vancomycin 40 mg/kg/day for 72 h was initiated with a diagnosis of chondrocostal osteoarthritis.
Blood cultures were positive for Klebsiella pneumoniae sensitive to oxyiminocephalosporins, amikacin, gentamicin, meropenem and imipenem.
Vancomycin was discontinued and continued with meropenem for 14 days, with negative blood cultures on day 7 of therapy.
I felt feverish and local signs but continued to be limited to right hip rotation.
With the diagnosis of probable hip osteoarthritis, joint puncture and surgical drainage were performed, which resulted in purulent material.
At that time, amikacin 15 mg/kg/day was added due to the history of K. pneumoniae isolated from the blood culture.
Culture of the articular fluid yielded K. pneumoniae (OA1 strain) with the same susceptibility profile as the strain isolated in blood.
Since fever persisted, successive surgical silks were performed, being isolated 17 days after the first isolate (OA1), K. pneumoniae (OA2 strain) resistant to oxyiminocephalosporins, gentamicin.
Blood cultures performed during evolution were negative, maintaining the same antibacterial scheme.
Immunological evaluation was normal.
After multiple surgical debridements, 35 days of fever and 45 days of antibacterial treatment were discharged with good subsequent evolution.
Molecular titration and resistance mechanism: EFCP analysis showed that OA1 and OA2 strains were not genetically related.
Unlike strain OA1, OA2 presented the gene for ESBL CTX-M-9 in a non-conjugative IncHI1-HI2 plasmid.
In addition, OA2 showed the aac(6')1b gene, which confers resistance to amikacin and a class 1 ion with the aadB-aadA2 genes in the variable region, responsible for resistance.
