Activity of ceftaroline and comparators against pathogens isolated from skin and soft tissue infections in Latin America - results of AWARE surveillance 2012

ABSTRACT As part of the Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) surveillance program in 2012 the in vitro activity of ceftaroline and relevant comparator antimicrobials was evaluated in six Latin American countries (Argentina, Brazil, Chile, Colombia, Mexico and Venezuela) against pathogens isolated from patients with hospital associated skin and soft tissue infections (SSTIs). The study documented that ceftaroline was highly active (MIC90 0.25 mg/L/% susceptible 100%) against methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus (MIC90 2 mg/L/% susceptible 83.3%) and ß-hemolytic streptococci (MIC90 0.008-0.015 mg/L/% susceptible 100%). The activity of ceftaroline against selected species of Enterobacteriaceae was dependent upon the presence or absence of extended-spectrum ß-lactamases (ESBLs). Against ESBL screen-negativeEscherichia coli, Klebsiella pneumoniae, andKlebsiella oxytoca the MIC90 and percent susceptible for ceftaroline were (0.5 mg/L/94.1%), (0.5 mg/L/99.0%) and (0.5 mg/L/91.5%), respectively. Ceftaroline demonstrated potent activity against a recent collection of pathogens associated with SSTI in six Latin American countries in 2012.

Multicenter assessment of the linezolid spectrum and activity using the disk diffusion and Etest methods: report of the Zyvox(R) antimicrobial potency study in Latin America (LA-ZAPS)

Linezolid was the first clinically applied member of the new antimicrobial class called the oxazolidinones. These agents have a powerful spectrum of activity focussed against Gram-positive organisms including strains with documented resistances to other antimicrobial classes. We conducted a multicenter surveillance (Zyvox Antimicrobial Potency Study; ZAPS) trial of qualifying Gram-positive isolates from 24 medical centers in eight countries in Latin America. The activity and spectrum of linezolid was compared to numerous agents including glycopeptides, quinupristin/dalfopristin, beta-lactams and fluoroquinolones when testing 2,640 strains by the standardized disk diffusion method or Etest (AB BIODISK, Solna, Sweden). The linezolid spectrum was complete against staphylococci (median zone diameter, 29 - 32 mm), as was the spectrum of vancomycin and quinupristin/dalfopristin. Among the enterococci, no linezolid resistance was detected, and the susceptibility rate was 93.1 - 96.4. Only the vancomycin-susceptible Enterococcus faecium strains remained susceptible (92.8) to quinupristin/dalfopristin. Marked differences in the glycopeptide resistance patterns (van A versus van B) were noted for the 22 isolates of VRE, thus requiring local susceptibility testing to direct therapy. Streptococcus pneumoniae and other species were very susceptible (100.0) to linezolid, MIC(90) at 0.75 microg/ml. Penicillin non-susceptible rate was 27.7 and erythromycin resistance was at 17.4. Other streptococci were also completely susceptible to linezolid (MIC(90), 1 microg/ml). These results provide the initial benchmark of potency and spectrum for linezolid in Latin American medical centers. Future comparisons should recognize that the oxazolidinones possess essentially a complete spectrum coverage of the monitored staphylococci, enterococci and streptococcal isolates in 2000-2001. This positions linezolid as the widest spectrum empiric choice against multi-resistant Gram-positive cocci, a spectrum of activity greater than available glycopeptides and the streptogramin combination.

Antimicrobial susceptibility of Quinupristin/Dalfopristin tested against Gram-positive Cocci from Latin America: results from the global SMART (GSMART) surveillance study

Gram-positive cocci are important causes of both nosocomial and community-acquired infections, and antimicrobial resistance among these pathogens has become an important problem worldwide. Since resistance among these organisms can vary substantially by geographic location, we conducted a multicenter surveillance study with isolates from live Latin American countries (15 medical centers). Quinupristin/dalfopristin (formerly RP-59500) is a novel streptogramin combination with focused activity against Gram-positive cocci, many exhibiting emerging resistance. The in vitro activity of quinupristin/dalfopristin and 12 other antimicrobial agents were evaluated against 1,948 strains including Staphycoccus aureus (747 strains), coagulase-negative staphylococci (CoNS;446 strains), enterococci (429 strains), and various Streptococcus spp.(326 strains). Oxacillin resistance was observed in 41 percent of S. aureus (MIC,<2µg/ml or >13mm) and 40 percent of CoNS (MIC,<0.25µg/ml or >18mm). Vancomycin, teicoplanin, and quinupristin/dalfopristin (MIC90,,0.25-1µg/ml remained effective against all strains, but cross-resistance was high among other tested drugs. The quinupristin/dalfopristin MIC50 for Streptococcus pneumoniae and other streptococci was only 0.5µg/ml (13 percent to 28 percent were penicillin-resistant; 12 percent to 22 percent were macrolide-resistant). Enterococci demostrated variable inhibition by quinupristin/dalfopristin depending upon identification and the susceptibility testing method used. The demonstrated quinupristin/dalfopristin activity against Enterococcus faecium was confirmed, but potential species identification errors with various commercial systems continue to confuse susceptibility statistics, even though some strains of E. faecium confirmed by PCR-based or other molecular identification technique did have quinupristin/dalfopristin MICs of>4µg/mL. Most important, glycopeptide-resistant enterococci are rapidly emerging in Latin America, and quinupristin/dalfopristin appears active against many of these isolates as well as having potency against nearly all staphylococci and streptococci tested at<2µg/ml or having a zone diameter of>116mm. Comparisons to GSMART results from other continents show nerly identifical quinupristin/dalfopristin activity for each Gram-positive species tested. These results define the role of quinupristin/dalfopristin in Latin American medical centers and provide a bechmark for future in vitro comparisons.