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Surgical Infections,
Jun 2001, Vol. 2, No. supplement 1 : 23 -32
The Role of β-Lactam/β-Lactamase Inhibitor Combinations in Surgical
Infections
IskenderSayek Hacettepe University School of Medicine, Ankara, TurkeyMany
surgical infections are characterized by synergistic polymicrobial mixed infection,
for which broad-spectrum antimicrobial therapy is usually administered on an
empiric basis. Until relatively recently, standard empiric therapeutic regimens
have involved the use of two or more antibiotics, such as aminoglycosides
and anti-anaerobic agents, to achieve adequate aerobic and anaerobic
coverage. There are often substantial drawbacks, however, such as drug-
induced toxicity and high costs of treatment. Evidence from a number of
clinical studies suggests that single-agent therapy with β-lactam/β-lactamase
inhibitor combinations is a suitable and cost-effective alternative to
multidrug regimens, as well as to monotherapy with cephalosporins or
carbapenems in the treatment of intra-abdominal, gynecologic, and diabetic
foot infections, and brain abscesses. These agents are also suitable for use in
perioperative prophylaxisand may offer benefits over other agents in terms of
reduced incidence of surgical wound infections and lower costs.
Disadvantages of standard empiric therapeutic regimens
use of two or more antibiotics,
such as aminoglycosides (e.g. Gentamicin, Amikacin)and anti-
anaerobic agents (Metronidazole),
•to achieve adequate aerobic and anaerobic coverage.
•Drug-induced toxicityand high costs of treatment.
Justification of single-agent therapy with β-lactam/β-lactamase
inhibitor combinations
•is a suitable and cost-effective alternative to multidrug regimens, as
well as to monotherapy with cephalosporins or carbapenems in the
treatment of
•intra-abdominal, gynecologic, and diabetic foot infections, and
brain abscesses.
•also suitable for use in perioperative prophylaxis
•reduced incidence of surgical wound infections and lower costs.
The Role of β-Lactam/β-Lactamase Inhibitor Combinations in Surgical Infections
Interactions of tazobactam and clavulanate with
inducibly-and constitutively-expressed Class I ß-
lactamases
(piperacillin + tazobactam &ticarcillin + clavulanate)
Tazobactam, but not clavulanate,also had some ability to inhibit the AmpC
Class I enzymes ofM. morganii, C. freundii, Ps. aeruginosa, E. cloacae and S.
marcescens.
The piperacillin + tazobactam combination, unliketicarcillin + clavulanate, showed
some degree of synergy againstmost derepressed strains of these species.
This behaviour partlydepended upon the greater inhibitory activity of
tazobactamfor the enzymes.
Antagonism characteristics
The synergy between piperacillin and tazobactamwas greatest for M. morganii and
C. freundii, least for Ps.aeruginosa and E. cloacae.
Unfortunately, it is in the lasttwo species that these enzymes pose the greatest
resistancethreat Tazobactam caused little or no antagonism of piperacillin
against ß-lactamase inducible species, whereas clavulanateantagonized ticarcillin
against ß-lactamase induciblestrains of E. cloacae and M. morganii(not other
species).
Theantagonism of ticarcillin was attributable to ß-lactamaseinduction. The
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15th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID)
02.04.2005 -05.04.2005
In vitro activity of antimicrobial agents
Effect of beta-lactamase-inhibitor concentrations on in vitro test results with
piperacillin/tazobactam and piperacillin/sulbactam
H. Grimm, J. Wagner, A.C. Rodloff (Weingarten, Berlin, Leipzig, D)
Objectives: Recently, DIN 58940 was altered, now recommending to test the beta-lactamase
inhibiting effect of Sulbactam in presence of a constant concentration of 4 mg/L instead of previously
8 mg/L. The present study was performed to assess the effect of this change on the MIC
distributions of E. coli for Piperacillin/Sulbactam (P/S) as compared to Piperacillin/Tazobactam (P/T)
with Tazobactam tested at a concentration of 4 mg/L.
Methods: The in-vitro activity of Piperacillin without and with Tazobactam or Sulbactam, respectively,
against E. coli (n = 2856 in Leipzig, n = 420 in Berlin) was tested by means of microdilution MIC
determinations as recommended by DIN 58940 using a fixed concentration of 4 mg/L of Tazobactam
and 4 as well as 8 mg/L of Sulbactam.
Results: On the basis of MIC breakpoints according to DIN, the superiority of P/T over P/S is
maximal in Piperacillin-resistant E. coliand minimal in Piperacillin-intermediate E. coli. The
recently recommended reduction of the fixed Sulbactam concentration (from 8 to 4 mg/L) in
susceptibility tests leads to reduced susceptibility in Piperacillin-intermediate E. coli, too. The results
are as follows: (table)
Conclusion: The recently recommended 4 mg/L fixed concentration of Sulbactam in testing
procedures shows that the in-vitro activity of P/T exceed those of P/S not only in Piperacillin-resistant
but also in Piperacillin-intermediate E. coli. These results are credible because of the stronger
inhibition of TEM-1 lactamases by Tazobactam in comparison to Sulbactam.
Effect of beta-lactamase-inhibitor concentrations on in vitro test results with
piperacillin/tazobactam and piperacillin/sulbactam
test the beta-lactamase inhibiting effect of Sulbactam in presence of a
constant concentration of 4 mg/L instead of previously 8 mg/L.
the MIC distributions of E. coli for Piperacillin/Sulbactam (P/S) as compared
to Piperacillin/Tazobactam (P/T) with Tazobactam tested at a concentration
of 4 mg/L.
Results: On the basis of MIC breakpoints according to DIN, the
superiority of P/T over P/S is maximal in Piperacillin-resistant E. coli
and minimal in Piperacillin-intermediate E. coli.
Conclusion:It shows that the in-vitro activity of P/T exceedthose of P/S
notonly in Piperacillin-resistant but also in Piperacillin-intermediate E.
coli.
These results are credible because of the stronger inhibition of TEM-1
lactamases by Tazobactam in comparison to Sulbactam.