Pathogens that are increasingly resistant to available antibiotics make it difficult to treat infections caused by these organisms. In a recent webinar, Jason Gallagher, PharmD., FCCP, BCPS outlined appropriate treatment strategies for managing antimicrobial-resistant pathogens and identified alternative pharmacotherapy regimens to treat resistant infections.
Antibiotics are difficult to develop. Gallagher noted that antibiotic development has decreased steadily from 1983 through 2013, with a very slight increase noted in the last two years. And it is not just inappropriate use of antibiotics that drives resistance, it is any use of antibiotics that leads to resistance.
Gallagher also reviewed the following drug-resistant organisms and treatment options.
Methicillin-Resistant Staph aureus (MRSA): MRSA is a very common organism that is a major cause of healthcare-associated infections (HAIs). It accounts for almost half of annual deaths due to multi-drug resistant organisms (MDROs). Overall incidence of this organism is decreasing. Regarding therapies, an early switch from vancomycin to daptomycin demonstrated clinical efficacy and decreased mortality in patients with MRSA bloodstream infections.
Vancomycin-Resistant Enterococcus (VRE): This organism cause opportunistic infections. Regarding therapies, wo meta analyses showed an advantage to linezolid over daptomycin in VRE bloodstream infections, but a large cohort study in the VA system showed worse outcomes with linezolid. Gallagher added that daptomycin has a lower MIC than linezolid and reviewed other therapies, including ampicillin and ceftriaxone, which may work well against VR E. faecalis and is recommended for strains with high-level gentamicin resistance
Pseudomonas aeruginosa: This organism is intrinsically resistant to many antibiotics and has acquired resistance to many others. Extended infusion, as opposed to intermittent infusion, of Piperacillin/tazobactam decreases mortality in Pseudomonas infections. Extended infusion Cefepime also decreases mortality.
C. difficile: This infection is associated with prior antibiotic use and gastric acid suppression. Vancomycin is associated with greater clinical success. Fidaxomicin is the second agent approved to treat C. diff and a study demonstrated decreased readmission rates due to a lower incidence of recurrence.
Patients with C. diff have experienced excellent results with a fecal microbiota transplant.
Extended Spectrum Beta-lactamase (ESBL) Producing GNRs: This group of beta-lactamase producers confer resistance to 1st-3rd generation cephalosporins (not Cefotetan or Cefoxitin), penicillins, and aztreonam. E. coli and K. pneumoniae are most problematic organisms. Gallagher provided many therapy options, including fosfomycin, nitrofurantoin, fluoroquinolones and tigecycline.
Carbapenem-Resistant Enterobacteriaceae (CRE): Primarily K. pneumoniae but seen in Enterobacter, E. coli, and other species, CRE is often resistant to all or nearly all antibiotics.
Treatment options for CRE are severely limited to polymixin, aminoglycosides, tetracyclines, fosfomycin, or combination therapies. Gallagher noted that a double carbapenems therapy of ertapenem and meropenem showed success in two case series.
For further details, you can download the webinar here.