Community-associated extended-spectrum ß-lactamase-producing Escherichia coli infection in the United States.

Background. The occurrence of community-associated infections due to extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli has been recognized as a major clinical problem in Europe and other regions. Methods. We conducted a prospective observational study to examine the occurrence of community-associated infections due to ESBL-producing E. coli at centers in the United States. Five academic and community hospitals and their affiliated clinics participated in this study in 2009 and 2010. Sites of acquisition of the organisms (community-associated or healthcare-associated), risk factors, and clinical outcome were investigated. Screening for the global epidemic sequence type (ST) 131 and determination of the ESBL types was conducted by polymerase chain reaction and sequencing. Results. Of the 291 patients infected or colonized with ESBL-producing E. coli as outpatients or within 48 hours of hospitalization, 107 (36.8%) had community-associated infection (81.5% of which represented urinary tract infection), while the remainder had healthcare-associated infection. Independent risk factors for healthcare-associated infection over community-associated infection were the presence of cardiovascular disease, chronic renal failure, dementia, solid organ malignancy, and hospitalization within the previous 12 months. Of the community-associated infections, 54.2% were caused by the globally epidemic ST131 strain, and 91.3% of the isolates produced CTX-M-type ESBL. Conclusions. A substantial portion of community-onset, ESBL-producing E. coli infections now occur among patients without discernible healthcare-associated risk factors in the United States. This epidemiologic shift has implications for the empiric management of community-associated infection when involvement of E. coli is suspected.

Prevalence and genetic relatedness of methicillin-susceptible Staphylococcus aureus isolates detected by the Xpert MRSA nasal assay.

Methicillin-susceptible Staphylococcus aureus (MSSA) isolates lacking mecA yet testing positive on the Xpert MRSA assay were recovered from culture for 7.7% of 248 Xpert-positive nasal samples. These "false-positive" Xpert results may be attributed to staphylococcal cassette chromosome (SCC) elements without the mecA gene. Pulsed-field gel electrophoresis (PFGE) analysis revealed a diverse population of MSSA strains.

Comparison of BD Phoenix AP Workflow with Vitek 2.

The BD Phoenix AP instrument reduced the manual setup time for the Phoenix system by 50%. For batches of 14 organisms, the average manual manipulation time per isolate was 89.5 s for BD Phoenix by the use of the AP instrument and 101 s for Vitek 2 (P<0.001).

Multicenter evaluation of the BD Phoenix Automated Microbiology System for antimicrobial susceptibility testing of Streptococcus species.

This multicenter study evaluated the BD Phoenix Automated Microbiology System STREP panel (BD Diagnostic Systems). Antimicrobial susceptibility testing (AST) with 13 agents was performed on 2,013 streptococci (938 Streptococcus pneumoniae isolates; 396 group B streptococci [GBS]; 369 viridans group streptococci [VGS]; 290 beta-hemolytic streptococcus groups A, C, and G; and 20 other streptococci) with the Phoenix system and a broth microdilution reference method. Clinical and challenge isolates were tested against cefepime, cefotaxime (CTX), ceftriaxone (CTR), clindamycin (CLI), erythromycin (ERY), gatifloxacin, levofloxacin, linezolid, meropenem, penicillin (PEN), tetracycline (TET), trimethoprim-sulfamethoxazole, and vancomycin. Clinical isolates with major errors or very major errors (VMEs) were retested in duplicate by both methods. The final results for clinical isolates showed the following trends. For all of the organism-antimicrobial agent combinations tested, categorical agreement (CA) was 92 to 100%, with one exception-VGS-PEN (87% CA; all errors were minor). For S. pneumoniae, there was one major error with CLI (0.1%) and one or two VMEs with CTX (4%), CTR (4.5%), ERY (0.9%), and TET (0.7%). For groups A, C, and G, the CA was 97 to 100% and the only VMEs were resolved by additional reference laboratory testing. For GBS, there was only one VME (TET, 0.3%) and D-zone testing of 23 isolates with CLI major errors (one isolate unavailable) revealed inducible CLI resistance. For VGS, the major error rates were 0 to 3% and VMEs occurred with seven agents (3.5 to 7.1%). The mean times required for organism groups to generate results ranged from 8.4 to 9.4 h. The Phoenix system provided reliable and rapid AST results for most of the organism-antimicrobial agent combinations tested.