Cefoperazone microbiology
CEFOBID is active in vitro against a wide range of aerobic and anaerobic, gram-positive and gram-negative pathogens. The bactericidal action of CEFOBID results from the inhibition of bacterial cell wall synthesis. CEFOBID has a high degree of stability in the presence of beta-lactamases produced by most gram-negative pathogens. CEFOBID is usually active against organisms which are resistant to other beta-lactam antibiotics because of beta-lactamase production. CEFOBID is usually active against the following organisms in vitro and in clinical infections:
Gram-Positive Aerobes
Staphylococcus aureus, penicillinase and non-penicillinase-producing strains
Staphylococcus epidermidis
Streptococcus pneumoniae (formerly Diplococcus pneumoniae)
Streptococcus pyogenes (Group A beta-hemolytic streptococci)
Streptococcus agalactiae (Group B beta-hemolytic streptococci)
Enterococcus (Streptococcus faecalis, S. faecium and S. durans)
Gram-Negative Aerobes
Escherichia coli
Klebsiella species (including K. pneumoniae)
Enterobacter species
Citrobacter species
Haemophilus influenzae
Proteus mirabilis
Proteus vulgaris
Morganella morganii (formerly Proteus morganii)
Providencia stuartii
Providencia rettgeri (formerly Proteus rettgeri)
Serratia marcescens
Pseudomonas aeruginosa
Pseudomonas species
Some strains of Acinetobacter calcoaceticus
Neisseria gonorrhoeae
Anaerobic Organisms
Gram positive cocci (including Peptococcus and Peptostreptococcus)
Clostridium species
Bacteroides fragilis
Other Bacteroides species
CEFOBID is also active in vitro against a wide variety of other pathogens although the clinical significance is unknown. These organisms include:Salmonella and Shigella species, Serratia liquefaciens, N. meningitidis, Bordetella pertussis, Yersinia enterocolitica, Clostridium difficile, Fusobacteriumspecies, Eubacterium species and beta-lactamase producing strains of H. influenzae and N. gonorrhoeae.

# SUSCEPTIBILITY TESTING
Diffusion Technique
For the disk diffusion method of susceptibility testing, a 75 mcg CEFOBID diffusion disk should be used. Organisms should be tested with the CEFOBID 75 mcg disk since CEFOBID has been shown in vitro to be active against organisms which are found to be resistant to other beta-lactam antibiotics.Tests should be interpreted by the following criteria:
Quantitative procedures that require measurement of zone diameters give the most precise estimate of susceptibility. One such method which has been recommended for use with the CEFOBID 75 mcg disk is the NCCLS approved standard. (Performance Standards for Antimicrobial Disk Susceptibility Tests. Second Information Supplement Vol. 2 No. 2 pp. 4969. PublisherNational Committee for Clinical Laboratory Standards, Villanova, Pennsylvania.)
A report of "susceptible" indicates that the infecting organism is likely to respond to CEFOBID therapy and a report of "resistant" indicates that the infecting organism is not likely to respond to therapy. A "moderately susceptible" report suggests that the infecting organism will be susceptible to CEFOBID if a higher than usual dosage is used or if the infection is confined to tissues and fluids (e.g., urine or bile) in which high antibiotic levels are attained.
Dilution Techniques
Broth or agar dilution methods may be used to determine the minimal inhibitory concentration (MIC) of CEFOBID. Serial twofold dilutions of CEFOBID should be prepared in either broth or agar. Broth should be inoculated to contain 5  105 organism/mL and agar "spotted" with 104 organisms.
MIC test results should be interpreted in light of serum, tissue, and body fluid concentrations of CEFOBID. Organisms inhibited by CEFOBID at 16 mcg/mL or less are considered susceptible, while organisms with MICs of 1763 mcg/mL are moderately susceptible. Organisms inhibited at CEFOBID concentrations of greater than or equal to 64 mcg/mL are considered resistant, although clinical cures have been obtained in some patients infected by such organisms.