Articles

<i>Roseomonas</i><i> mucosa</i> is a slow-growing, pink-pigmented, Gram-negative coccobacillus historically considered an opportunistic pathogen in severely immunocompromised oncology patients. However, recent genomic and clinical data demonstrate its primary reservoir is the human skin microbiome, facilitating an evolving epidemiology. We report a case of <i>R. mucosa</i> bacteremia in a 69-year-old woman with short bowel syndrome (SBS) and total parenteral nutrition (TPN) dependence. This case supports an emerging pattern: <i>R. mucosa</i> is increasingly identified in "device-compromised" hosts. Furthermore, this pathogen may present without elevated host-response biomarkers and exhibits intrinsic resistance to empiric broad-spectrum beta-lactams, complicating early management.

<b>Background</b>: <i>Pseudomonas aeruginosa </i>(<i>P</i><i>.</i><i> aeruginosa</i>)<i> </i>is one of the most common pathogens in hospital-acquired pneumonia (HAP) including ventilator-associated pneumonia (VAP). Recently, ceftolozane/tazobactam (CTLZ/TAZ) has been used to treat pneumonia due to<i> P</i><i>.</i><i> aeruginosa</i>. <b>Case series</b>: Two cases of <i>P</i><i>.</i><i> aerugi</i><i>n</i><i>osa</i> pneumonia treated by CTLZ/TAZ that had been initially treated by piperacillin/tazobactam (PIPC/TAZ) are presented. (Case 1): A 76-year-old man who underwent esophagectomy developed severe pneumonia caused by <i>P</i><i>.</i><i> aeruginosa </i>infection and received oxygen by high-flow nasal canula. PIPC/TAZ was started, and he improved 10 days later. PIPC/TAZ was switched to sulbactam/ampicillin, but on day 14, his respiratory condition worsened, and septic shock developed. <i>P</i><i>.</i><i> aeruginosa</i> was isolated from his blood, and CTLZ/TAZ was started because the isolated <i>P</i><i>.</i><i> aeruginosa</i> showed resistance to PIPC/TAZ. Although he recovered on Day 28, and CTLZ/TAZ was switched to levofloxacin, his condition worsened again, and<i> P</i><i>.</i><i> aeruginosa </i>resistant to CTLZ/TAZ was isolated from his blood on day 32. Finally, he died of septicemia and renal failure. (Case 2) A 51-year-old woman who underwent surgery for a brain tumor developed VAP due to<i> P</i><i>.</i><i> aeruginosa </i>and was treated by PIPC/TAZ. Her pneumonia improved, but pneumothorax developed, and she was therefore switched to CTLZ/TAZ on day 7. Her pneumonia improved smoothly without bacteremia 10 days later. <b>Conclusions:</b> These data and cases suggest that CTLZ/TAZ was effective for severe <i>P</i><i>.</i><i> aeruginosa</i> pneumonia although the isolated <i>P</i><i>.</i><i> aeruginosa</i> was resistant to PIPC/TAZ. However, the duration of CTLZ/TAZ administration may need to be considered for pneumonia cases with bacteremia due to <i>P</i><i>.</i><i> aeruginosa</i>.