Objectives
To comparatively evaluate the antimicrobial activities of colistin and polymyxin B with those of other antimicrobials against a worldwide collection of 40 625 Gram-negative bacilli.
...Methods
Antimicrobial susceptibility testing was performed and interpreted using the CLSI broth microdilution method except for colistin against Enterobacteriaceae.
Results
The polymyxins showed potent in vitro activities (MIC90, ≤0.5-1 mg/L) against this large collection of clinical isolates, with very low resistance rates (<0.1%-1.5%). Resistance to the polymyxins remained stable among organisms tested except for Klebsiella spp. isolates collected from the Asia-Pacific and Latin American regions, where a trend towards greater resistance was observed (P ≤ 0.05). In addition, an important reduction in imipenem susceptibility among Acinetobacter spp. and Klebsiella spp. was demonstrated in most geographical regions.
Conclusions
Although the polymyxins showed excellent in vitro activity against the vast majority of Gram-negative bacilli evaluated, a trend to greater resistance was observed in the Asia-Pacific and Latin American regions. Therefore, the clinical use of polymyxins must be cautious and surveillance monitored.
Abstract This study updates the frequency and resistance rates of Gram-negative bacilli isolated from Latin American medical centers enrolled in the SENTRY Antimicrobial Surveillance Program. A total ...of 12,811 bacterial organisms, including 5704 Gram-negative bacilli (44.5%), were consecutively collected (1 per patient) between January 2008 and December 2010 from 10 Latin American medical centers located in Argentina, Brazil, Chile, and Mexico. Antimicrobial susceptibility testing was performed and interpreted by the Clinical and Laboratory Standards Institute broth microdilution method at a central laboratory. All Gram-negative organisms with reduced susceptibility to imipenem or meropenem (MIC, ≥ 2 μg/mL) were screened for carbapenemase production by the modified Hodge test and by polymerase chain reaction. ESBL rates were 18.1%, 12.8%, 23.8%, and 48.4% among Escherichia coli and 60.4%, 49.9%, 59.2%, and 33.3% among Klebsiella spp. from Argentina, Brazil, Chile, and Mexico, respectively. Meropenem-nonsusceptible Klebsiella spp. rate was highest in Brazil (11.1%), followed by Argentina (8.2%), Chile (5.0%), and Mexico (0.8%). Klebsiella pneumoniae carbapenemase (KPC)–producing K. pneumoniae was not detected in 2008, but emerged in 2009 (10 strains) and increased significantly in 2010 (44; P < 0.0001). blaKPC-2 was detected in 54 (65.9%) of 85 carbapenem-nonsusceptible K. pneumoniae. Meropenem-nonsusceptible P. aeruginosa was observed in 53.8%, 46.7%, 33.3%, and 28.8% of strains from Argentina, Brazil, Chile, and Mexico, respectively. Imipenem-resistant Acinetobacter spp. rates increased from 6.4%, 12.6%, and 0.0% in the 1997–1999 period to 84.9%, 71.4%, and 50.0% in 2008–2010 in Argentina, Brazil, and Chile, respectively. Oxacillinase (OXA)-producing Acinetobacter spp. was documented in Argentina (OXA-23 and -24), Brazil (OXA-23), Chile (OXA-58), and Mexico (OXA-24). Only colistin showed > 77% overall coverage against the 5 most frequently isolated Gram-negative bacilli from Latin American Medical centers participating in the SENTRY Program.
Abstract
Background
Despite the advances in current healthcare, bone and joint infections (BJIs) are a major clinical challenge that frequently involve prolonged systemic antibiotic use. Healthcare ...providers consider tedizolid an attractive candidate for therapy in adults and children with BJI.
Objectives
We tested tedizolid against a US and European collection of Gram-positive BJI isolates (n = 797) consecutively collected from 2014 to 2017.
Methods
Organisms were tested by broth microdilution susceptibility methods following current CLSI guidelines and interpreted by both CLSI and EUCAST breakpoint criteria.
Results
Staphylococcus aureus (59.3%; 58.6% in the USA and 60.4% in Europe) was the most common pathogen with a 29.6% MRSA rate and tedizolid MIC50/90 of 0.12/0.25 mg/L (100% susceptible). CoNS (15.0% of BJI in adults and <5% in children) had tedizolid MIC50/90 values of 0.12/0.12 mg/L (99.1% susceptible). Tedizolid exhibited MIC50/90 values of 0.12/0.25 mg/L for all streptococci and enterococci. Overall, high susceptibility rates (>95%) for vancomycin, daptomycin and linezolid were observed and, based on MIC90 values, tedizolid (MIC90 0.12–0.25 mg/L) was 4- to 8-fold more potent than linezolid (MIC90 0.5–2 mg/L) against this collection of Gram-positive pathogens causing BJI.
Conclusions
This study showed that tedizolid had potent in vitro activity against contemporary Gram-positive cocci causing BJI in adults and children in US and European hospitals.
Bloodstream infection (BSI) organisms were consecutively collected from >200 medical centers in 45 nations between 1997 and 2016. Species identification and susceptibility testing followed Clinical ...and Laboratory Standards Institute broth microdilution methods at a central laboratory. Clinical data and isolates from 264,901 BSI episodes were collected. The most common pathogen overall was
(20.7%), followed by
(20.5%),
(7.7%),
(5.3%), and
(5.2%).
was the most frequently isolated pathogen overall in the 1997-to-2004 period, but
was the most common after 2005. Pathogen frequency varied by geographic region, hospital-onset or community-onset status, and patient age. The prevalence of
isolates resistant to oxacillin (ORSA) increased until 2005 to 2008 and then declined among hospital-onset and community-acquired BSI in all regions. The prevalence of vancomycin-resistant enterococci (VRE) was stable after 2012 (16.4% overall). Daptomycin resistance among
and enterococci (DRE) remained rare (<0.1%). In contrast, the prevalence of multidrug-resistant (MDR)
increased from 6.2% in 1997 to 2000 to 15.8% in 2013 to 2016. MDR rates were highest among nonfermentative Gram-negative bacilli (GNB), and colistin was the only agent with predictable activity against
complex (97% susceptible). In conclusion,
and
were the predominant causes of BSI worldwide during this 20-year surveillance period. Important resistant phenotypes among Gram-positive pathogens (MRSA, VRE, or DRE) were stable or declining, whereas the prevalence of MDR-GNB increased continuously during the monitored period. MDR-GNB represent the greatest therapeutic challenge among common bacterial BSI pathogens.
Background: In Brazil, carbapenem use has been limited by high carbapenem-resistance rates among Pseudomonas aeruginosa isolates. Objective: The main objective of this study was to evaluate the ...presence of an epidemic P. aeruginosa strain in unrelated Brazilian hospitals. We also aimed to search for the gene blaSPM, which encodes production of SPM, a novel metallo-β-lactamase (MBL). Methods: A reference broth microdilution method was used for antimicrobial susceptibility testing. The isolates were typed by ribotyping and pulsed-field gel electrophoresis (PFGE). A disc-approximation test using MBL inhibitors was employed to screen isolates for MBL production. PCR was used to search for the gene blaSPM. Results: A total of 43 clinical isolates of carbapenem-resistant P. aeruginosa were collected from 12 hospitals. Colistin retained greatest activity in vitro. A single ribogroup included 17 P. aeruginosa isolates (39.5%) collected from seven unrelated hospitals located in five Brazilian states. Sixteen of these isolates showed an identical PFGE pattern, and 15 produced an SPM-1-like MBL. The remaining 26 isolates were grouped into 25 diverse ribogroups; none were MBL producers. Conclusions: The emergence and dissemination of an epidemic clone has contributed to the high carbapenem resistance rates among P. aeruginosa isolates in Brazil. In addition, the production of SPM MBL has an important role in carbapenem resistance in this region. This is the first report of dissemination of an SPM-1-like-MBL-producing strain of P. aeruginosa among unrelated Brazilian hospitals.
We report the first linezolid-resistant
Staphylococcus aureus strain isolated in Brazil. The strain was isolated from a 10-year-old female patient with cystic fibrosis (CF) who received repeated and ...prolonged courses of low-dose linezolid. The strain belonged to the Brazilian endemic methicillin-resistant
S. aureus clone, and the G2576U mutation was identified in domain V of the 23S rRNA. Detection of this mechanism of resistance in a CF patient is very worrisome, as these patients may become a reservoir for further dissemination of resistant strains. Our findings emphasise the importance of optimal dosage of linezolid to prevent the emergence of resistance.
represents a major cause of health care-associated infections, and inappropriate initial antimicrobial therapy is associated with increased morbidity and mortality. The International Network for ...Optimal Resistance Monitoring (INFORM) program monitors the
activity of ceftazidime-avibactam and many comparator agents. We evaluated the antimicrobial susceptibility of 7,452
isolates collected from 79 U.S. medical centers in 2012 to 2015. The isolates were collected and tested consecutively for susceptibility by broth microdilution method. Infection types included mainly pneumonia (50.5%), skin and skin structure (24.0%), urinary tract (7.8%), and bloodstream (7.7%) infections. The only compounds with >90% susceptibility rates were colistin (MIC
, 1/2 mg/liter, respectively; 99.4% susceptible), ceftazidime-avibactam (MIC
, 2/4 mg/liter, respectively; 97.0% susceptible), and amikacin (MIC
, 2/8 mg/liter, respectively; 97.0/93.0% susceptible CLSI/EUCAST, respectively). The addition of avibactam to ceftazidime increased the percentage of susceptible
isolates from 84.3% to 97.0%. Multidrug resistance (MDR) and extensive drug resistance (XDR) phenotypes were observed among 1,151 (15.4%) and 698 (9.4%) isolates, respectively, and ceftazidime-avibactam inhibited 82.1 and 75.8% of these isolates at ≤8 mg/liter, respectively. High rates of cross-resistance were observed with ceftazidime, meropenem, and piperacillin-tazobactam, whereas ceftazidime-avibactam retained activity against isolates nonsusceptible to ceftazidime (81.0% susceptible), meropenem (86.2% susceptible), and piperacillin-tazobactam (85.4% susceptible), as well as isolates nonsusceptible to these three β-lactams (71.2% susceptible). The only antimicrobial combinations that provided a better overall anti-
coverage than ceftazidime-avibactam (97.0% susceptibility rate) were those including amikacin (97.0 to 98.4% coverage). Susceptibility rates remained stable during the study period. The results of this investigation highlight the challenge of optimizing empirical antimicrobial therapy for
infections.
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