The Clinical Evaluation of Third-generation Cephalosporins As Definitive Therapy for Enterobacter spp. and Klebsiella aerogenes Bacteremia.

Objective Third-generation cephalosporins (3GCs) may be susceptible in vitro to Enterobacter spp. and Klebsiella aerogenes. However, treatment with mainly fourth-generation cephalosporins or carbapenems is currently recommended. Diversification of antimicrobial agents in therapy is required to avoid the selection pressure of resistant organisms by broad-spectrum antimicrobial agents. This study investigated the clinical efficacy of 3GC therapy for Enterobacter spp. and Klebsiella aerogenes bacteremia in a multicenter, retrospective, observational study. Methods Patients with Enterobacter spp. or Klebsiella aerogenes detected in blood cultures and treated with a susceptible antimicrobial agent were included in the study. Propensity score matching was performed to align patient background bases, and clinical outcomes between the 3GC and non-3GC groups were compared. Treatment success was defined as having no need for treatment escalation or the addition of other antimicrobial agents, no recurrence, or no death within 30 days. Results The study included 188 cases, of which 57 and 131 were included in the 3GC and non-3GC treatment groups, respectively; 53 patients in each group were matched by propensity score matching. There were no significant differences between groups in rates of switching to a susceptible antimicrobial or adding another agent, relapse within 30 days, or death within 30 days. In the 3GC group, source control was associated with favorable clinical outcomes. Conclusion Definitive 3GC therapy for susceptible Enterobacter spp. and Klebsiella aerogenes bacteremia is as clinically effective and valuable a targeted therapy as non-3GC therapy and can be implemented under conditions in which infection source control measures are in place.

Successful Conservative Treatment of Mycotic Pulmonary Artery Aneurysms Caused by MRSA Bacteremia.

Mycotic pulmonary artery aneurysms (MPAAs) are rare and life-threatening with currently no recommended treatment strategies. In this report, we describe a successfully treated case of ventricular septal defect in an 11-month-old girl who developed bacteremia, infective endocarditis, and MPAA caused by methicillin-resistant Staphylococcus aureus (MRSA). We first started vancomycin, gentamycin, and panipenem-betamipron for infective endocarditis but switched to teicoplanin and arbekacin on day 3 after initiating treatment because bacteremia persisted, and vancomycin minimum inhibitory concentration was relatively high at 2 mg/L. Although we added clindamycin on day 5 and fosfomycin on day 7, MRSA bacteremia persisted, and we finally added daptomycin at 10 mg/kg per day on day 8, whereupon the bacteremia subsided within a day. Although the bacteremia subsided, the patient developed septic pulmonary embolisms and septic arthritis on her left knee. We continued daptomycin but switched the concomitant drug to linezolid, trimethoprim-sulfamethoxazole, and rifampicin on day 11. After several repeats of puncture and lavage of her knee joint, she became afebrile on day 16. Computed tomography scans taken on day 32 revealed right pulmonary artery MPAAs. She was treated with long-term multidrug therapy, and MPAAs were absent on subsequent computed tomography scans on day 184. Multidrug therapy mainly based on daptomycin could be a possible salvage therapy for refractory MRSA bacteremia with high vancomycin minimum inhibitory concentration. Conservative treatment should be selectively considered as a treatment option for clinically stable MPAA instead of surgical and endovascular treatment.