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ABSTRACT: Telavancin is approved in the United States and Canada for the treatment of complicated skin and skin structure infections (cSSSI) in adults caused by susceptible Gram-positive organisms. The antimicrobial activity of telavancin and comparators was evaluated against 5,027 (2007-2008) Gram-positive bacteria responsible for SSSI in medical centers in Asia-Pacific, European, Latin American, and North American regions. Telavancin was active against Staphylococcus aureus (MIC₅₀(/)₉₀, 0.12/0.25 mg/l; 100.0% susceptible) and coagulase-negative staphylococci (MIC₅₀(/)₉₀, 0.12/0.25 mg/l). telavancin inhibited all Enterococcus faecalis, including four strains displaying a VanB phenotype, at ≤ 1 mg/L (MIC₅₀(/)₉₀, 0.25/0.5 mg/l), except for two isolates with a VanA phenotype (MIC, >2 mg/l). Vancomycin-susceptible and VanB vancomycin-resistant E. faecium were inhibited by telavancin at ≤ 0.25 mg/L, while this drug exhibited elevated MIC values (≥ 0.5 mg/l) against E. faecium of VanA phenotype (MIC₅₀(/)₉₀, 2/>2 mg/l). Telavancin was potent against β-haemolytic streptococci (MIC₅₀(/)₉₀, 0.03/0.12 mg/l; 100.0% susceptible) and viridans group streptococci (MIC₅₀(/)₉₀, 0.03/0.06 mg/l; 100.0% susceptible). These in vitro data document the activity of telavancin against contemporary Gram-positive isolates and support its clinical use for the treatment of cSSSI caused by the indicated pathogens.
Journal of chemotherapy (Florence, Italy) 10/2010; 22(5):304-11. · 1.08 Impact Factor
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ABSTRACT: We evaluate the antimicrobial interactions between aztreonam and selected beta-lactams when tested against metallo-beta-lactamase (MbetaL)-producing clinical strains. Ten Pseudomonsa aeruginosa strains, including nine MbetaL-producers (IMP-1, -2, -13, -16, VIM-1, -2, -7, SPM-1 and GIM-1) and five Acinetobacter baumannii strains, including three MbetaL-producers (IMP-1 and -2) were tested using time kill/bactericidal activity methods. Aztreonam at 4, 8 and 16 mg/L was combined with four other beta-lactam antimicrobials (cefepime, ceftazidime, meropenem and piperacillin/tazobactam or ampicillin/sulbactam), each tested at the recognized susceptible breakpoint concentration. Enhanced activity (synergism or additive effect) was observed with four P. aeruginosa strains (IMP-16, VIM-2, SPM-1 and GIM-1 containing strains) and four A. baumannii strains, while antagonism was observed with two P. aeruginosa (IMP-16 and SPM-1-producing strains) and one A. baumannii (non-MbetaL) strain. All other strains showed indifferent interaction (variation of +/- 1 log10 CFU/ml) with any combination evaluated.
Journal of chemotherapy (Florence, Italy) 01/2006; 17(6):622-7. · 1.08 Impact Factor
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ABSTRACT: The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal resistance surveillance network of more than 100 medical centers worldwide monitoring the susceptibility of bacterial pathogens to carbapenems and other broad-spectrum agents. In 2004 (year six), the antimicrobial activity of 12 broad-spectrum agents was assessed against 2,799 Gram-negative bacterial isolates submitted from 15 United States (USA) medical centers using Clinical and Laboratory Standards Institute (CLSI; formerly NCCLS) recommended methods. Meropenem continued to demonstrate a high potency with MIC90 values 4- to 32-fold lower than imipenem against the Enterobacteriaceae. The wide spectrum of activity for meropenem against all Gram-negative isolates was demonstrated by the overall rank order of percentage susceptibility at CLSI breakpoints: amikacin (96.5%) > meropenem (96.0%) > imipenem (95.8%) > piperacillin/tazobactam (91.5%) > tobramycin (91.4%) > cefepime (91.2%) > ceftazidime (89.0%) > gentamicin (88.0%) > aztreonam (81.5%) > levofloxacin (80.5%) > ciprofloxacin (80.2%) > ceftriaxone (69.1%). Only the aminoglycosides (84.5%) and carbapenems (76.1-83.8%) exhibited acceptable levels of susceptibility against the Acinetobacter spp. isolates as this species group became more resistant to all antimicrobial classes. A continued increase in the resistance rate for both ciprofloxacin and levofloxacin over the six years was observed, most alarming among Escherichia coli (20.2-20.7%) and indole-positive Proteus species (34.4-42.2%) isolates, some documented as clonal. Continued surveillance of these broad-spectrum antimicrobial agents appears warranted to monitor the potency and spectrum of activity against Gram-negative pathogens causing serious infections and the emergence of new or novel resistance mechanisms that could compromise carbapenem therapy.
Journal of chemotherapy (Florence, Italy) 10/2005; 17(5):459-69. · 1.08 Impact Factor
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ABSTRACT: A total of 1,531 recent clinical isolates of Streptococcus pneumoniae were collected from 33 medical centers nationwide during the winter of 1999--2000 and characterized at a central laboratory. Of these isolates, 34.2% were penicillin nonsusceptible (MIC > or = 0.12 microg/ml) and 21.5% were high-level resistant (MIC > or = 2 microg/ml). MICs to all beta-lactam antimicrobials increased as penicillin MICs increased. Resistance rates among non-beta-lactam agents were the following: macrolides, 25.2 to 25.7%; clindamycin, 8.9%; tetracycline, 16.3%; chloramphenicol, 8.3%; and trimethoprim-sulfamethoxazole (TMP-SMX), 30.3%. Resistance to non-beta-lactam agents was higher among penicillin-resistant strains than penicillin-susceptible strains; 22.4% of S. pneumoniae were multiresistant. Resistance to vancomycin and quinupristin-dalfopristin was not detected. Resistance to rifampin was 0.1%. Testing of seven fluoroquinolones resulted in the following rank order of in vitro activity: gemifloxacin > sitafloxacin > moxifloxacin > gatifloxacin > levofloxacin = ciprofloxacin > ofloxacin. For 1.4% of strains, ciprofloxacin MICs were > or = 4 microg/ml. The MIC(90)s (MICs at which 90% of isolates were inhibited) of two ketolides were 0.06 microg/ml (ABT773) and 0.12 microg/ml (telithromycin). The MIC(90) of linezolid was 2 microg/ml. Overall, antimicrobial resistance was highest among middle ear fluid and sinus isolates of S. pneumoniae; lowest resistance rates were noted with isolates from cerebrospinal fluid and blood. Resistant isolates were most often recovered from children 0 to 5 years of age and from patients in the southeastern United States. This study represents a continuation of two previous national studies, one in 1994--1995 and the other in 1997--1998. Resistance rates with S. pneumoniae have increased markedly in the United States during the past 5 years. Increases in resistance from 1994--1995 to 1999--2000 for selected antimicrobial agents were as follows: penicillin, 10.6%; erythromycin, 16.1%; tetracycline, 9.0%; TMP-SMX, 9.1%; and chloramphenicol, 4.0%, the increase in multiresistance was 13.3%. Despite awareness and prevention efforts, antimicrobial resistance with S. pneumoniae continues to increase in the United States.
Antimicrobial Agents and Chemotherapy 07/2001; 45(6):1721-9. · 4.84 Impact Factor
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ABSTRACT: During a 14-month period, 7 patients with hematological malignancies acquired serious infections caused by a single strain of multiply resistant Pseudomonas aeruginosa. A case-control study, culture surveys, and pulsed-field gel electrophoresis implicated a whirlpool bathtub on the unit as the reservoir. All case patients and 32% of control patients used this bathtub (P=.003). The epidemic strain was found only in cultures of samples taken from the bathtub. The drain of the whirlpool bathtub, which was contaminated with the epidemic strain, closed approximately 2.54 cm below the drain's strainer. Water from the faucet, which was not contaminated, became contaminated with P. aeruginosa from the drain when the tub was filled. The design of the drain allowed the epidemic strain to be transmitted to immunocompromised patients who used the whirlpool bathtub. Such tubs are used in many hospitals, and they may be an unrecognized source of nosocomial infections. This potential source of infection could be eliminated by using whirlpool bathtubs with drains that seal at the top.
Clinical Infectious Diseases 01/2001; 31(6):1331-7. · 9.15 Impact Factor
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ABSTRACT: Group B streptococcal infection is a common cause of neonatal sepsis. Surveillance of antimicrobial susceptibility and serotype frequencies of invasive group B streptococci is important to ensure the effectiveness of therapeutic regimens and to guide vaccine development.
Prospective surveillance of neonatal bloodstream infection was performed at all Western Hemisphere sites participating in the SENTRY Program. From January 1997 through December 1999, a total of 122 isolates of bloodstream infections with group B streptococci were collected and sent to the University of Iowa for antimicrobial susceptibility testing and serotyping.
No isolates were resistant to penicillin. More than 25% of isolates from US hospitals and 14% of isolates from Canadian hospitals were erythromycin resistant. Seven percent of isolates from the United States and Canada were resistant to clindamycin. No clindamycin or erythromycin resistance was found among isolates from Latin America. Clindamycin and erythromycin resistance was most frequent among serotype V strains.
No emerging resistance to penicillin was noted among bloodstream infection isolates of group B streptococci from a broad geographic area; erythromycin and clindamycin resistance was found in the United States and Canada and appeared most frequently among serotype V strains.
American Journal of Obstetrics and Gynecology 11/2000; 183(4):859-62. · 3.47 Impact Factor
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ABSTRACT: The beta-lactamases from 403 Moraxella (Branhamella) catarrhalis clinical isolates obtained during 1994-1995 and 1997-1998 U.S. multicenter surveillance studies were characterized by isoelectric focusing. The overall prevalences of the BRO-1 and BRO-2 enzymes among beta-lactamase-positive isolates were estimated to be 97.5 and 2.5%, respectively. The minimum inhibitory concentrations (MICs) of ampicillin for all BRO-2-producing isolates were </=1 microg/ml; however, numerous beta-lactamase-positive isolates for which the ampicillin MICs were </=1 microg/ml produced the BRO-1 enzyme (88. 1%).
Antimicrobial Agents and Chemotherapy 03/2000; 44(2):444-6. · 4.84 Impact Factor
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ABSTRACT: The in vitro activity of ABT-773 was evaluated against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolates. ABT-773 was the most active antimicrobial tested against S. pneumoniae. ABT-773 and azithromycin were equivalent in activity against H. influenzae and M. catarrhalis and more active than either clarithromycin or erythromycin.
Antimicrobial Agents and Chemotherapy 03/2000; 44(2):447-9. · 4.84 Impact Factor
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ABSTRACT: From November 1, 1997 to April 30, 1998, 726 Moraxella catarrhalis isolates and 1529 Haemophilus influenzae isolates were obtained from 34 medical centres throughout the United States. Rates of beta-lactamase production were 94.6% among M. catarrhalis and 31.1% among H. influenzae strains. Susceptibility rates of M. catarrhalis isolates to selected antimicrobial agents were greater than 99% for amoxycillin-clavulanate, cefixime, cefpodoxime, cefuroxime, cefaclor, loracarbef, clarithromycin, azithromycin, chloramphenicol and tetracycline, 97.8% for cefprozil, 50.4% for trimethoprim-sulphamethoxazole and 28.1% for ampicillin. Of the antimicrobials tested against H. influenzae, the only agents with susceptibility rates below 96% were loracarbef (87.6%), cefprozil (83.4%), cefaclor (82.7%), trimethoprim-sulphamethoxazole (67.3%) and ampicillin (64.7%). The clarithromycin susceptibility rate was 67.4% but this agent was not tested in the presence of its 14-OH metabolite.
International Journal of Antimicrobial Agents 11/1999; 13(2):99-107. · 4.13 Impact Factor
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ABSTRACT: Invasive infections caused by Neisseria meningitidis continue to be a serious clinical problem for therapy, epidemiology, and potential prophylaxis. Multiple antimicrobial resistances have emerged among meningococcal strains including elevated MICs to penicillin, sulfonamides, tetracyclines, and rifampin. Thus, the need to perform accurate susceptibility testing of meningococci in clinical practice and for surveillance programs has renewed priority. In this study, for the first time Etest (AB Biodisk, Solna, Sweden) was compared to a reference agar dilution method using a large number (100) of clinical strains selected for a range of drug resistances. Etest quantitative accuracy (+/-one log2 dilution agreement) ranged from 94% (penicillin) to 100% (three drugs) for the eight clinically useful antimicrobial agents tested. Intermethod categorical accuracy for all drug ranged from 92% (penicillin, erythromycin) to 100% (five drugs), without false-susceptible or -resistant errors using Etest. Etest and reference methods were highly reproducible (99.6 to 100.0%, respectively). Quantitative discords between methods (> or = two log2 dilutions) were not reproducible and resolved following repeated testing. Etest method proved to be an accurate and reproducible quantitative method for testing N. meningitidis strains for the compared antimicrobial agents (eight) often utilized for therapy and prophylaxis of serious meningococcal disease.
Diagnostic Microbiology and Infectious Disease 04/1997; 27(3):93-7. · 2.53 Impact Factor
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ABSTRACT: Development of antimicrobial testing for Legionella spp. has been technically compromised by the fastidious growth requirements of this organism and by the most commonly used medium, buffered charcoal yeast extract agar (BCYE) that contains substances known to inhibit some antimicrobial agents. This study validated the potency of two newer antimicrobials (sparfloxacin and imipenem) and their Etest strip. The comparisons of antimicrobial minimum inhibitory concentration (MIC) values as determined by Etest on BCYE agar (98 Legionella pneumophila) demonstrated that sparfloxacin was the most potent drug (MIC90, 0.19 microgram/ml) among the fluoroquinolones, macrolides, tetracyclines, and beta-lactams tested. Imipenem MICs (MIC90, < or = 0.38 microgram/ml) were also determined by a reference agar dilution method and validated Etest strips on buffered yeast extract agar, buffered charcoal yeast extract agar, and buffered charcoal yeast extract agar with defined supplements. The non-Legionella control strains used to demonstrate medium component influences on the imipenem MICs demonstrated the addition of supplements (particularly L-cysteine) markedly elevated the MICs. These data indicate that the Etest was a simple and accurate quantitative method for susceptibility tests with Legionella isolates. Sparfloxacin among the fluoroquinolones and imipenem among the beta-lactams require further clinical studies for legionellosis therapy.
Diagnostic Microbiology and Infectious Disease 11/1994; 20(3):159-62. · 2.53 Impact Factor
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ABSTRACT: Development of susceptibility tests for Legionella spp. has been difficult because of the specific growth requirements of this organism. The most commonly used media, buffered charcoal-yeast extract (BCYE) agar contains charcoal, which is known to inactivate some antimicrobial agents. This study compared five antimicrobial (erythromycin, clindamycin, ofloxacin, doxycycline, and rifampin) minimum inhibitory concentration (MIC) values as determined by agar dilution using BCYE, agar dilution using this same media without the charcoal [buffered yeast extract (BYE) agar], and the Etest on BCYE media. The MIC50 and MIC90 for this group of Legionella spp. were greater with BCYE than with BYE. Erythromycin and ofloxacin (fourfold change) were the most affected by the charcoal in the medium. The Etest MIC and agar dilution MIC with BYE were comparable. The Etest rifampin results demonstrated that the Legionella spp. strains were very susceptible (< 0.016 micrograms/ml, producing very large zones) requiring use of one half of the Etest strip, a whole test strip on an individual 100-mm plate of BCYE, or use of a new low-MIC-range Etest strip. The Etest on BCYE provides a simple, readily available, and accurate method unaffected by medium components for susceptibility testing of Legionella spp.
Diagnostic Microbiology and Infectious Disease 08/1994; 19(3):175-8. · 2.53 Impact Factor
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ABSTRACT: Three commercially available systems (API Staph-Trac, API 20GP, and Vitek GPI), used to identify coagulase-negative staphylococci, were evaluated against 277 bloodstream isolates, including 94 isolates of Staphylococcus epidermidis and 183 isolates of other coagulase-negative Staphylococcus species. The conventional method of Kloos and Schleifer served as the reference method. Controls included 14 ATCC type culture strains of coagulase-negative staphylococci. The API Staph-Trac system showed the highest rate of agreement with reference method, correctly identifying 73% of the isolates. The Vitek GPI System had an overall rate of agreement of 67% and the API 20GP system correctly identified 61%. The API Staph-Trac system correctly identified 94% of the isolates of S. epidermidis compared with 64% by both Vitek GPI and API 20GP. The most common error for both Vitek GPI and API 20GP systems was the failure to identify organisms contained within the database of the systems. Because none of the tested commercial identification systems identified "non-epidermidis" coagulase-negative Staphylococcus species with a high degree of accuracy, the systems need to be markedly improved or new systems developed.
Diagnostic Microbiology and Infectious Disease 04/1994; 18(3):151-5. · 2.53 Impact Factor
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ABSTRACT: BMS284756, a novel des-fluoro (6) quinolone (formerly T-3811), was tested for activity and spectrum using reference agar dilution (AD) and Etest (AB BIODISK, Solna, Sweden) methods. The antimicrobial activities of BMS284756, ciprofloxacin, gatifloxacin, levofloxacin, and trovafloxacin were evaluated against Campylobacter jejuni (38 strains), Helicobacter pylori (21 strains), Legionella spp. (66 strains), and 197 anaerobic isolates. BMS284756 (MIC(90), 0.008 microg/mL) was four-fold more active than gatifloxacin and trovafloxacin against H. pylori strains. Gatifloxacin and BMS284756 (MIC(50), 0.03 microg/mL) were > or = two-fold more active than levofloxacin against C. jejuni, but their spectrums were judged equivalent overall (89.4% susceptible). Against the Legionella spp., ciprofloxacin and levofloxacin (MIC(90), 0.25 microg/mL) had two-fold greater activity compared to gatifloxacin or BMS284756, but all strains were considered inhibited at clinically achievable levels. BMS284756 and trovafloxacin (MIC(90), 2 and 4 microg/mL, respectively) were four-to-eight-fold more potent than other comparators against the Gram-negative anaerobic species. Against the Gram-positive anaerobes (dominated by Clostridium difficile; 61 strains), BMS284756 activity was generally reduced, but equivalent or superior to trovafloxacin (68% inhibited at < or = 4 microg/mL). Inter-method comparisons (Etest versus AD) of BMS284756 MIC values showed a high correlation for C. jejuni and anaerobes (93.3 to 97.6% +/- two log (2) dilution steps). In conclusion, BMS284756 was very active against C. jejuni, H. pylori, Legionella spp. and most anaerobes, thus the potential role of this des-fluoro compound for treatment of infections caused by these fastidious species warrants further investigation.
Diagnostic Microbiology and Infectious Disease 40(1-2):45-9. · 2.53 Impact Factor
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ABSTRACT: The purpose of this study was to estimate the prevalence of Neisseria meningitidis with decreased susceptibility to penicillin (MIC, >0.06 microg/mL) in North America (NA). Antimicrobial susceptibility testing by Etest (AB BIODISK, Solna, Sweden) was performed on 53 invasive clinical isolates obtained from 11 SENTRY Antimicrobial Surveillance Program participants in NA (9 states, 2 provinces) during 1998-99. All strains were markedly susceptible to ciprofloxacin (MIC(90), 0.008 microg/mL) and cefotaxime (MIC(90), < or = 0.002 microg/mL). Only 54.7% were susceptible to trimethoprim-sulfamethoxazole (TMP/SMX) at < or = 0.5/9.5 microg/mL. One strain was resistant to rifampin (MIC, > 32 microg/mL) and 16 isolates (30.2%) were relatively resistant to penicillin with MICs ranging from 0.094 to 0.25 microg/mL. No beta-lactamase production was detected. The serogroup distribution was 40% Y, 28% B, 24% C, 2% W-135, and 6% of strains were nongroupable. The prevalence of N. meningitidis with decreased susceptibility to penicillin in NA appears higher than previous reports.
Diagnostic Microbiology and Infectious Disease 41(1-2):83-8. · 2.53 Impact Factor
