Previous Article | Next Article ![]()
Antimicrobial Agents and Chemotherapy, June 2001, p. 1915-1918, Vol. 45, No. 6
The Clinical Microbiology Institute, Wilsonville,
Oregon 97070
Received 8 August 2000/Returned for modification 17 December
2000/Accepted 8 March 2001
This study compared the in vitro activities of the new
long-half-life carbapenem ertapenem (also known as
MK-0826 and L-749,345) with those of imipenem,
amoxicillin-clavulanate, and ciprofloxacin against 5,558 recent
clinical isolates from 11 North American medical centers. We confirmed
the greater activity of ertapenem than of imipenem
against the Enterobacteriaceae and the greater activity
of imipenem against pseudomonads and gram-positive bacteria.
Ertapenem (also known
as MK-0826 and L-749,345) is a new long-half-life carbapenem with a
broad spectrum of antimicrobial activity against both gram-positive and
gram-negative bacteria (1-4, 7). Preliminary
pharmacokinetic studies indicate that ertapenem has a prolonged
half-life (half-life at For these studies, 5,558 bacterial isolates were obtained from the 11 North American medical centers listed at the end of this paper. These
isolates included 2,019 nonfastidious gram-negative bacteria, 540 fastidious gram-negative bacteria, 2,789 gram-positive isolates, and
210 anaerobes. Each center was requested to collect consecutive
isolates that were deemed clinically significant during late winter to
early spring of 1999. For each species, collection continued until a
predefined target number of isolates was obtained or until the
collection period ended. Multiple isolates from one patient were not
included so that the consecutive isolates truly represent bacterial
pathogens being encountered at that time. All isolates submitted for
testing were identified by each contributing laboratory using their own
standard methods. All susceptibility tests were performed at the
Clinical Microbiology Institute, Wilsonville, Oreg. The species and
numbers of each species tested are listed in Table
1.
0066-4804/01/$04.00+0 DOI: 10.1128/AAC.45.6.1915-1918.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
In Vitro Activities of Ertapenem (MK-0826) against Clinical
Bacterial Isolates from 11 North American Medical Centers
![]()
ABSTRACT
Top
Abstract
Text
References
![]()
TEXT
Top
Abstract
Text
References
phase of 4.9 ± 0.7 h) sufficient
to permit once-a-day dosing (2, 8). This long half-life is
largely due to its high protein binding of >95% (8).
Ertapenem MICs found in the presence of serum were no
more than eightfold higher than in standard tests (I. Pelak, S. Gerckens, P. M. Scott, C. Gill, C. Pacholok, L. Lynch, K. Dorso,
J. Kohler, D. Shungu, and H. Kropp, Abstr. 36th Intersci. Conf.
Antimicrob. Agents Chemother., abstr. F119, p. 120, 1996). In animal
studies the high protein binding had no apparent deleterious effect on
ertapenem's in vivo efficacy (2). Peak levels in plasma of human volunteers following a 1.0-g intravenous dose were
>100 µg/ml (8). The drug is currently undergoing
clinical trials. The present study was designed to assess the in vitro activity of ertapenem in comparison with those of
imipenem, amoxicillin-clavulanate, and ciprofloxacin against
clinical isolates from 11 North American medical centers.
TABLE 1.
Susceptibilities of 5,558 clinical isolates to
ertapenem and three comparator drugs
Ertapenem and imipenem were provided as standardized
powders by Merck Research Laboratories, Rahway, N.J.
Ciprofloxacin, amoxicillin-clavulanate, and ampicillin were
obtained from their respective U.S. manufacturers or other commercial
source. All aerobic bacteria were evaluated by broth microdilution
methods as outlined by the NCCLS (5). Microdilution
panels were prepared by PML Microbiologicals, Wilsonville, Oreg., and
stored at
70°C until used. The cation-adjusted Mueller-Hinton broth
was supplemented with ca. 3% lysed horse blood when necessary for
growth (e.g., streptococci). Haemophilus test medium was used for
testing Haemophilus species. Concentrations of drugs tested were serial twofold dilutions ranging from 16 to 0.008 µg/ml for ertapenem, imipenem, and ciprofloxacin; 32 to 0.03 µg/ml for amoxicillin-clavulanate; and 4.0 to 0.03 for ampicillin
(fastidious gram-negative isolates only). Anaerobic bacteria were
tested by the agar dilution method recommended by the NCCLS
(6), using Brucella blood agar supplemented with vitamin
K1 (1.0 µg/ml) and hemin (5 µg/ml) and using
an inoculum of ca. 105 CFU per spot.
On each day of testing, colony counts were performed on the bacterial suspension in the growth control wells of two randomly selected microdilution trays to ensure an inoculum density of approximately 5 × 105 CFU/ml. Standard control strains that were included with each test run were those that were appropriate for the species of clinical isolates being tested.
Table 1 summarizes the antimicrobial activities of ertapenem and three comparison agents against 5,558 strains of clinical bacterial isolates. Ertapenem was more active against all species of Enterobacteriaceae than imipenem. Ertapenem MICs were generally 10 to 20 times lower than those of imipenem for most species and were over 100 times lower for some species of the tribe Proteeae. Against Pseudomonas aeruginosa and related species, both drugs were less active than against the Enterobacteriaceae, but imipenem was more active than ertapenem. Amoxicillin-clavulanate was the least active of the four drugs tested against nonfastidious gram-negative bacteria. Ciprofloxacin MICs were generally slightly higher than those of ertapenem and lower than those of imipenem for Enterobacteriaceae, and for most species of non-Enterobacteriaceae they were lower than those of the other drugs tested.
Ertapenem was active against gram-positive bacteria other than enterococci and oxacillin-resistant staphylococci (Table 1). Imipenem was more potent than ertapenem against nearly all gram-positive species. The MICs of ertapenem and imipenem were higher for penicillin-resistant pneumococci (MICs at which 90% of the isolates tested were inhibited [MIC90], 2.0 and 1.0 µg/ml) than against penicillin-susceptible pneumococci (MIC90, 0.03 and 0.016 µg/ml). The geometric mean MICs of both carbapenems were 40-fold higher for penicillin-resistant pneumococci than for penicillin-susceptible strains. A similar difference in MICs was observed with amoxicillin-clavulanate, but ciprofloxacin MICs were unaffected by penicillin susceptibility of pneumococci.
Fastidious gram-negative bacteria, except for ampicillin resistance of
-lactamase-producing Haemophilus spp., were highly susceptible to all four test drugs (Table 1). For
Haemophilus spp., the MICs of ertapenem were 2- to
10-fold lower than those of imipenem.
-Lactamase production
by H. influenzae had no perceptible effect on the MICs of
either carbapenem or ciprofloxacin.
Virtually all anaerobic isolates tested were susceptible to
4.0 µg
of both carbapenems per ml (Table 1). Against Clostridium perfringens, ertapenem was twice as active as
imipenem, but against the other anaerobic bacteria,
imipenem was more potent.
In summary, ertapenem was superior to the other study drugs in its potency against the Enterobacteriaceae but it had relatively little activity against Pseudomonas spp. Although ertapenem was active against most gram-positive cocci, imipenem was somewhat more potent. Both carbapenems had little activity against the enterococci, especially vancomycin-resistant strains. Anaerobic bacteria were also susceptible to both carbapenems even though imipenem was more potent than ertapenem. Because ertapenem may be given once a day and because of its potency against the Enterobacteriaceae, ertapenem might be useful in treating a variety of infections in humans.
| |
ACKNOWLEDGMENTS |
|---|
We gratefully acknowledge the following for providing the clinical isolates for this study: M. Bauman, Providence St. Vincent Medical Center, Portland, Oreg; T. Cleary, University of Miami, Miami, Fla.; M. J. Ferraro, Massachusetts General Hospital, Boston; D. Hardy, University of Rochester Medical Center, Rochester, N.Y.; J. Hindler, UCLA Medical Center, Los Angeles, Calif.; S. Jenkins, Carolinas Medical Center, Charlotte, N.C.; G. Overturf, University of New Mexico Medical Center, Albuquerque; R. Rennie, University of Alberta Hospital, Edmonton, Alberta, Canada; K. Waites, University of Alabama at Birmingham, Birmingham; G. Procop, The Cleveland Clinic Foundation, Cleveland, Ohio; and P. Murray, Washington University School of Medicine, St. Louis, Mo.
This study was supported by a financial grant from Merck Research Laboratories, Rahway, N.J.
| |
FOOTNOTES |
|---|
* Corresponding author. Mailing address: Clinical Microbiology Institute, 9725 SW Commerce Circle, Wilsonville, OR 97070. Phone: (503) 682-3232. Fax: (503) 682-2065. E-mail: cmi{at}hevanet.com.
| |
REFERENCES |
|---|
|
|
|---|
| 1. |
Fuchs, P. C.,
A. L. Barry, and S. D. Brown.
1999.
In-vitro antimicrobial activity of a carbapenem, MK-0826 (L-749,345) and provisional interpretive criteria for disc tests.
J. Antimicrob. Chemother.
43:703-706 |
| 2. |
Gill, C. J.,
J. J. Jackson,
L. S. Gerckens,
B. A. Pelak,
R. K. Thompson,
J. G. Sundelof,
H. Kropp, and H. Rosen.
1998.
In vitro activity and pharmacokinetic evaluation of a novel long-acting carbapenem antibiotic, MK-826 (L-749,345).
Antimicrob. Agents Chemother.
42:1996-2001 |
| 3. |
Jacoby, G.,
P. Han, and J. Tran.
1997.
Comparative in vitro activities of carbapenem L-749,345 and other antimicrobials against multiresistant gram-negative clinical pathogens.
Antimicrob. Agents Chemother.
41:1830-1831 |
| 4. |
Kohler, J.,
K. L. Dorso,
K. Young,
G. G. Hammond,
H. Rosen,
H. Kropp, and L. L. Silver.
1999.
In vitro activities of the potent, broad-spectrum carbapenem MK-0826 (L-749,345) against broad-spectrum -lactamase- and extended-spectrum -lactamase-producing Klebsiella pneumoniae and Escherichia coli clinical isolates.
Antimicrob. Agents Chemother.
43:1170-1176 |
| 5. | National Committee for Clinical Laboratory Standards. 1997. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, 4th ed. Approved standard M7-A4. National Committee for Clinical Laboratory Standards, Wayne, Pa. |
| 6. | National Committee for Clinical Laboratory Standards. 1997. Methods for antimicrobial susceptibility testing of anaerobic bacteria, 4th ed. Approved standard M11-A4. National Committee for Clinical Laboratory Standards, Wayne, Pa. |
| 7. |
Odenholt, I.,
E. Lowdin, and O. Cars.
1998.
In vitro pharmacodynamic studies of L-749,345 in comparison with imipenem and ceftriaxone against gram-positive and gram-negative bacteria.
Antimicrob. Agents Chemother.
42:2365-2370 |
| 8. |
Sundelof, J. G.,
R. Hajdu,
C. J. Gill,
R. Thompson,
H. Rosen, and H. Kropp.
1997.
Pharmcokinetics of L-749,345, a long-acting carbapenem antibiotic, in primates.
Antimicrob. Agents Chemother.
41:1743-1748 |
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copyright © 2010 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»