Cefprozil has in vitro activity against a broad
range of gram-positive and gram-negative bacteria. The bactericidal action of
cefprozil results from inhibition of cell-wall synthesis. Cefprozil has been
shown to be active against most strains of the following microorganisms both
in vitro and in clinical infections as described in
the INDICATIONS AND USAGE
section.
Aerobic
Gram-Positive Microorganisms:
Staphylococcus aureus
(including ß-lactamase-producing strains)
NOTE: Cefprozil is inactive against
methicillin-resistant staphylococci.
Streptococcus pneumoniae
Streptococcus pyogenes
Aerobic
Gram-Negative Microorganisms:
Haemophilus influenzae
(including ß-lactamase-producing strains)
Moraxella (Branhamella) catarrhalis
(including ß-lactamase-producing strains)
The following in vitro data are available;
however, their clinical significance is unknown. Cefprozil exhibits in vitro minimum inhibitory concentrations (MICs) of 8
mcg/mL or less against most (≥90%) strains of the following microorganisms;
however, the safety and effectiveness of cefprozil in treating clinical
infections due to these microorganisms have not been established in adequate and
well-controlled clinical trials.
Aerobic
Gram-Positive Microorganisms:
Enterococcus durans
Enterococcus faecalis
Listeria monocytogenes
Staphylococcus epidermidis
Staphylococcus saprophyticus
Staphylococcus warneri
Streptococcus agalactiae
Streptococci (Groups C, D, F, and G)
viridans group Streptococci
NOTE: Cefprozil is inactive against Enterococcus faecium.
Aerobic
Gram-Negative Microorganisms:
Citrobacter diversus
Escherichia coli
Klebsiella pneumoniae
Neisseria gonorrhoeae
(including ß-lactamase-producing strains)
Proteus mirabilis
Salmonella spp.
Shigella spp .
Vibrio spp.
NOTE: Cefprozil is inactive against most strains of
Acinetobacter, Enterobacter, Morganella morganii, Proteus
vulgaris, Providencia, Pseudomonas, and Serratia.
Anaerobic
Microorganisms:
Prevotella (Bacteroides) melaninogenicus
Clostridium difficile
Clostridium perfringens
Fusobacterium spp.
Peptostreptococcus spp.
Propionibacterium acnes
NOTE: Most strains of the Bacteroides fragilis group are resistant to
cefprozil.
Susceptibility
Tests:
Dilution Techniques: Quantitative methods are used to determine
antimicrobial minimal inhibitory concentrations (MICs). These MICs provide
estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs
should be determined using a standardized procedure. Standardized procedures are
based on a dilution method1,2 (broth or agar) or
equivalent with standardized inoculum concentrations and standardized
concentrations of cefprozil powder. The MIC values should be interpreted
according to the following criteria:
MIC (mcg/mL) | Interpretation |
| ≤8 | Susceptible (S) |
| 16 | Intermediate (I) |
| ≥32 | Resistant (R) |
A report of "Susceptible" indicates that the pathogen is likely to be
inhibited if the antimicrobial compound in the blood reaches the concentrations
usually achievable. A report of "Intermediate" indicates that the result should
be considered equivocal, and, if the microorganism is not fully susceptible to
alternative, clinically feasible drugs, the test should be repeated. This
category implies possible clinical applicability in body sites where the drug is
physiologically concentrated or in situations where high dosage of drug can be
used. This category also provides a buffer zone which prevents small
uncontrolled technical factors from causing major discrepancies in
interpretation. A report of "Resistant" indicates that the pathogen is not
likely to be inhibited if the antimicrobial compound in the blood reaches the
concentrations usually achievable; other therapy should be selected.
Standardized susceptibility test procedures require the use of laboratory
control microorganisms to control the technical aspects of the laboratory
procedures. Standard cefprozil powder should provide the following MIC
values:
Microorganism
| MIC (mcg/mL) |
Enterococcus faecalis ATCC 29212 | 4-16 |
Escherichia coli ATCC 25922
| 1-4 |
Haemophilus influenzae ATCC 49766 | 1-4 |
Staphylococcus aureus ATCC 29213 | 0.25-1 |
Streptococcus pneumoniae ATCC 49619 | 0.25-1 |
Diffusion Techniques: Quantitative methods that require
measurement of zone diameters also provide reproducible estimates of the
susceptibility of bacteria to antimicrobial compounds. One such standardized
procedure3 requires the use of standardized inoculum
concentrations. This procedure uses paper disks impregnated with 30 mcg
cefprozil to test the susceptibility of microorganisms to cefprozil.
Reports from the laboratory providing results of the standard single-disk
susceptibility test with a 30 mcg cefprozil disk should be interpreted according
to the following criteria:
Zone diameter (mm) | Interpretation |
| ≥18 | Susceptible (S) |
| 15-17 | Intermediate (I) |
| ≤14 | Resistant (R) |
Interpretation should be as stated above for results using dilution
techniques. Interpretation involves correlation of the diameter obtained in the
disk test with the MIC for cefprozil.
As with standardized dilution techniques, diffusion methods require the use
of laboratory control microorganisms that are used to control the technical
aspects of the laboratory procedures. For the diffusion technique, the 30 mcg
cefprozil disk should provide the following zone diameters in these laboratory
test quality control strains.
Microorganism
| Zone diameter (mm) |
Escherichia coli ATCC 25922
| 21-27 |
Haemophilus influenzae ATCC 49766 | 20-27 |
Staphylococcus aureus ATCC 25923 | 27-33 |
Streptococcus pneumoniae ATCC 49619 | 25-32 |