Impact of different antimicrobial therapies on clinical and fiscal outcomes of patients with bacteremia due to vancomycin-resistant enterococci.

Vancomycin-resistant enterococci (VRE) are a growing health problem, and uncertainties exist regarding the optimal therapy for bloodstream infection due to VRE. We conducted systematic comparative evaluations of the impact of different antimicrobial therapies on the outcomes of patients with bloodstream infections due to VRE. A retrospective study from January 2008 to October 2010 was conducted at Detroit Medical Center. Unique patients with blood cultures due to VRE were included and reviewed. Three major therapeutic classes were analyzed: daptomycin, linezolid, and ß-lactams. Three multivariate models were conducted for each outcome, matching for a propensity score predicting the likelihood of receipt of one of the therapeutic classes. A total of 225 cases of bacteremia due to VRE were included, including 86 (38.2%) cases of VR Enterococcus faecalis and 139 (61.8%) of VR Enterococcus faecium. Bacteremia due to VR E. faecalis was more frequent among subjects treated with ß-lactams than among those treated with daptomycin or linezolid. The median dose of daptomycin was 6 mg/kg of body weight (range, 6 to 12 mg/kg). After controlling for propensity score and bacteremia due to VR E. faecalis, differences in mortality were nonsignificant among the treatment groups. Therapy with daptomycin was associated with higher median variable direct cost per day than that for linezolid. This large study revealed the three therapeutic classes (daptomycin, linezolid, and ß-lactams) are similarly efficacious in the treatment of bacteremia due to susceptible strains of VRE.

Epidemiology and risk factors for isolation of Escherichia coli producing CTX-M-type extended-spectrum ß-lactamase in a large U.S. Medical Center.

A case-case-control study was conducted to identify independent risk factors for recovery of Escherichia coli strains producing CTX-M-type extended-spectrum ß-lactamases (CTX-M E. coli) within a large Southeastern Michigan medical center. Unique cases with isolation of ESBL-producing E. coli from February 2010 through July 2011 were analyzed by PCR for blaCTX-M, blaTEM, and blaSHV genes. Patients with CTX-M E. coli were compared to patients with E. coli strains not producing CTX-M-type ESBLs (non-CTX-M E. coli) and uninfected controls. Of 575 patients with ESBL-producing E. coli, 491 (85.4%) isolates contained a CTX-M ESBL gene. A total of 319 (84.6%) patients with CTX-M E. coli (282 [74.8%] CTX-M-15 type) were compared to 58 (15.4%) non-CTX-M E. coli patients and to uninfected controls. Independent risk factors for CTX-M E. coli isolation compared to non-CTX-M E. coli included male gender, impaired consciousness, H2 blocker use, immunosuppression, and exposure to penicillins and/or trimethoprim-sulfamethoxazole. Compared to uninfected controls, independent risk factors for isolation of CTX-M E. coli included presence of a urinary catheter, previous urinary tract infection, exposure to oxyimino-cephalosporins, dependent functional status, non-home residence, and multiple comorbid conditions. Within 48 h of admission, community-acquired CTX-M E. coli (n = 51 [16%]) and non-CTX-M E coli (n = 11 [19%]) strains were isolated from patients with no recent health care contacts. CTX-M E. coli strains were more resistant to multiple antibiotics than non-CTX-M E. coli strains. CTX-M-encoding genes, especially bla(CTX-M-15) type, represented the most common ESBL determinants from ESBL-producing E. coli, the majority of which were present upon admission. Septic patients with risk factors for isolation of CTX-M E. coli should be empirically treated with appropriate agents. Regional infection control efforts and judicious antibiotic use are needed to control the spread of these organisms.

Tricuspid and mitral endocarditis due to methicillin-resistant Staphylococcus aureus exhibiting vancomycin-creep phenomenon.

Right-sided infective endocarditis (RIE) is commonly due to Staphylococcus aureus and often involves the tricuspid valve (TV). A 31-year-old man with prior intravenous drug use presented with substernal pain, cough, dyspnoea and fever. Examination revealed a febrile, tachycardic male with peripheral infective endocarditis stigmata and right-heart failure. Laboratory parameters demonstrated leucocytosis, lactic acidosis and methicillin-resistant S. aureus (MRSA) bacteraemia. Echocardiography demonstrated multiple TV echodensities and chest imaging confirmed septic emboli. The MRSA species demonstrated 'vancomycin-creep', necessitating therapy with daptomycin and ceftaroline. Owing to persistent bacteraemia and septic shock, the patient underwent TV surgery, but continued to have a poor postoperative course with subsequent death. Indications for surgical therapy of RIE are limited to the European guidelines and most data are extrapolated from left-heart disease. MRSA exhibiting vancomycin-creep portends a poorer prognosis and requires aggressive therapy. We advocate the use of ceftaroline salvage therapy with daptomycin, pending further trials.

Mycotic pseudoaneurysm by vancomycin-intermediate Staphylococcus aureus: a rare cause of persistent bacteraemia.

Pseudoaneurysms are vessel wall ruptures, that are often mistaken for deep vein thrombosis (DVT). A middle-aged man presented with right leg pain, swelling and erythema. His history was significant for persistent Staphylococcus aureus bacteraemia. Ultrasound revealed subacute DVT and laboratory parameters were suggestive of sepsis. He was started on intravenous heparin and antimicrobials. Owing to persistent anaemia despite blood transfusion, MRI of the right thigh was obtained. It revealed a 13×17 cm superficial femoral artery infected mycotic pseudoaneurysm (MPA) with a fresh haematoma. The patient underwent arterial ligation and extensive debridement. Intraoperative cultures revealed daptomycin-resistant vancomycin-intermediate S. aureus (VISA) and he was managed with 6 weeks of intravenous ceftaroline. MPAs are most common in the femoral artery and form <1% of aneurysms. Therapy involves surgical debridement and prolonged antimicrobials. VISA causing MPA is associated with worse outcomes. We report the first time use of ceftaroline in the management of a VISA MPA.

A rare nidus for pulmonary thromboembolism after vertebroplasty.

Percutaneous vertebroplasty is used to treat osteoporotic compression fractures and bone loss due to malignancy. The cement used can serve as a potential nidus for pulmonary thromboembolism (PTE). An 87-year-old woman with recent L2 vertebroplasty presented with abdominal pain and shortness of breath. Thoracoabdominal CT scan revealed extensive bilateral pulmonary emboli associated with a 9 cm cement fragment in the inferior vena cava (IVC) extending proximally from the level of the right superior renal vein, likely secondary to cement leak from the vertebral plexus into the IVC. She refused catheter extraction was managed conservatively. There are 51 reported cases of cement pulmonary embolism. IVC foreign bodies serving as a nidus for PTE have been reported with IVC filters with an incidence of 6.2%. This is the second reported case of vertebroplasty cement serving as a nidus for PTE. Treatment depends on time interval between the procedure and the symptom onset.