prophylaxis of rheumatic fever. cefaclor is generally effective in the eradication of streptococci from the nasopharynx; however, substantial data establishing the efficacy of cefaclor in the subsequent prevention of rheumatic fever are not available at present. urinary tract infections, including pyelonephritis and cystitis, caused by escherichia coli, proteus mirabilis, klebsiella spp ., and coagulase-negative staphylococci skin and skin structure infections caused by staphylococcus aureus and streptococcus pyogenes appropriate culture and susceptibility studies should be performed to determine susceptibility of the causative organism to cefaclor. to reduce the development of drug-resistant bacteria and maintain the effectiveness of cefaclor capsule and other antibacterial drugs, cefaclor capsule should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. when culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. in the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

ly all antibacterial agents, including cefaclor, and has ranged in severity from mild to life-threatening. therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents. treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. studies indicate that a toxin produced by clostridium difficile is one primary cause of antibiotic-associated colitis. after the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated. mild cases of pseudomembranous colitis usually respond to drug discontinuation alone. in moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation and treatment with an antibacterial drug effective against c. difficile.

in anuria is 2.3 to 2.8 hours, dosage adjustments for patients with moderate or severe renal impairment are usually not required. clinical experience with cefaclor under such conditions is limited; therefore, careful clinical observation and laboratory studies should be made. as with other β-lactam antibiotics, the renal excretion of cefaclor is inhibited by probenecid. antibiotics, including cephalosporins, should be prescribed with caution in individuals with a history of gastrointestinal disease, particularly colitis.

cond (or subsequent) course of therapy with cefaclor. such reactions have been reported more frequently in pediatric patients than in adults with an overall occurrence ranging from 1 in 200 (0.5%) in one focused trial to 2 in 8,346 (0.024%) in overall clinical trials (with an incidence in pediatric patients in clinical trials of 0.055%) to 1 in 38,000 (0.003%) in spontaneous event reports. signs and symptoms usually occur a few days after initiation of therapy and subside within a few days after cessation of therapy; occasionally these reactions have resulted in hospitalization, usually of short duration (median hospitalization = 2 to 3 days, based on postmarketing surveillance studies). in those requiring hospitalization, the symptoms have ranged from mild to severe at the time of admission with more of the severe reactions occurring in pediatric patients. antihistamines and glucocorticoids appear to enhance resolution of the signs and symptoms. no serious sequelae have been reported. more severe hypersensitivity reactions, including stevens-johnson syndrome, toxic epidermal necrolysis, and anaphylaxis have been reported rarely. anaphylactoid events may be manifested by solitary symptoms, including angioedema, asthenia, edema (including face and limbs), dyspnea, paresthesias, syncope, hypotension, or vasodilatation. anaphylaxis may be more common in patients with a history of penicillin allergy. rarely, hypersensitivity symptoms may persist for several months. gastrointestinal symptoms occur in about 2.5% of patients and include diarrhea (1 in 70). onset of pseudomembranous colitis symptoms may occur during or after antibiotic treatment. (see warnings ). nausea and vomiting have been reported rarely. as with some penicillins and some other cephalosporins, transient hepatitis and cholestatic jaundice have been reported rarely. other effects considered related to therapy included eosinophilia (1 in 50 patients), genital pruritus, moniliasis or vaginitis (about 1 in 50 patients), and, rarely, thrombocytopenia or reversible interstitial nephritis. causal relationship uncertain – cns ─ rarely, reversible hyperactivity, agitation, nervousness, insomnia, confusion, hypertonia, dizziness, hallucinations, and somnolence have been reported. transitory abnormalities in clinical laboratory test results have been reported. although they were of uncertain etiology, they are listed below to serve as alerting information for the physician. hepatic ─ slight elevations of ast, alt, or alkaline phosphatase values (1 in 40). hematopoietic ─ as has also been reported with other β-lactam antibiotics, transient lymphocytosis, leukopenia, and, rarely, hemolytic anemia, aplastic anemia, agranulocytosis, and reversible neutropenia of possible clinical significance. there have been rare reports of increased prothrombin time with or without clinical bleeding in patients receiving cefaclor and coumadin ® concomitantly. renal ─ slight elevations in bun or serum creatinine (less than 1 in 500) or abnormal urinalysis (less than 1 in 200). cephalosporin-class adverse reactions in addition to the adverse reactions listed above that have been observed in patients treated with cefaclor, the following adverse reactions and altered laboratory tests have been reported for cephalosporin-class antibiotics: fever, abdominal pain, superinfection, renal dysfunction, toxic nephropathy, hemorrhage, false positive test for urinary glucose, elevated bilirubin, elevated ldh, and pancytopenia. several cephalosporins have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. if seizures associated with drug therapy occur, the drug should be discontinued. anticonvulsant therapy can be given if clinically indicated (see dosage and administration and overdosage sections).

of cefaclor is slightly prolonged. in those with complete absence of renal function, the plasma half-life of the intact molecule is 2.3 to 2.8 hours. excretion pathways in patients with markedly impaired renal function have not been determined. hemodialysis shortens the half-life by 25% to 30%. microbiology mechanism of action as with other cephalosporins, the bactericidal action of cefaclor results from inhibition of cell-wall synthesis. mechanism of resistance resistance to cefaclor is primarily through hydrolysis of beta-lactamases, alteration of penicillin-binding proteins (pbps) and decreased permeability. pseudomonas spp ., acinetobacter calcoaceticus and most strains of enterococi ( enterococcus faecalis, group d streptococci), enterobacter spp ., indole-positive proteus, morganella morganii (formerly proteus morganii ), providencia rettgeri (formerly proteus rettgeri ) and serratia spp. are resistant to cefaclor. cefaclor is inactive against methicillin-resistant staphylococci. -lactamase-negative, ampicillin-resistant strains of h. influenzae should be considered resistant to cefaclor despite apparent in vitro susceptibility to this agent. antibacterial activity cefaclor 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. gram-positive bacteria staphylococcus aureus (methicillin susceptible only) coagulase negative staphylococci (methicillin susceptible only) streptococcus pneumoniae streptococcus pyogenes (group a -hemolytic streptococci) gram-negative bacteria escherichia coli haemophilus influenzae (excluding -lactamase-negative, ampicillin-resistant strains) klebsiella spp. proteus mirabilis the following in vitro data are available, but their clinical significance is unknown . at least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentrations (mics) less than or equal to the susceptible breakpoint of cefaclor. however, the safety and effectiveness of cefaclor in treating clinical infections due to these bacteria has not been established in adequate and well-controlled trials. gram-negative bacteria citrobacter diversus moraxella catarrhalis neisseria gonorrhoeae anaerobic bacteria bacteroides spp. peptococcus spp. peptostreptococcus spp. propionibacterium acnes susceptibility test methods when available, the clinical microbiology laboratory should provide the result of in vitro susceptibility test results for antimicrobial drugs used in resident hospitals to the physician as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. these reports should aid the physician in selecting an antibacterial drug for treatment. dilution techniques quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (mics). these mics provide estimates of the susceptibility of bacteria to antimicrobial compounds. the mics should be determined using a standardized method (broth, agar, or microdilution) 1,3 . the mic values should be interpreted according to criteria provided in table 1. diffusion techniques quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. the zone size provides an estimate of the susceptibility of bacteria to antimicrobial compounds. the zone size should be determined using a standardized test method 2,3 . this procedure uses paper disks impregnated with 30-mcg cefaclor to test the susceptibility of microorganisms to cefaclor. the disc diffusion interpretive criteria are provided in table 1. table 1: susceptibility test interpretive criteria for cefaclor table 1: susceptibility test interpretive criteria for cefaclor microorganisms 1,2 minimal inhibitory concentration (mcg/ml) zone diameter (mm) s i r s i r streptococcus pneumoniae ≤1 2 ≥4 -- -- -- 1 susceptibility of staphylococci to cefaclor may be deduced from testing only penicillin and either cefoxitin or oxacillin 2 susceptibility of streptococcus pyogenes to cefaclor may also be deduced from testing penicillin a report of susceptible indicates that antimicrobial is likely to inhibit growth of the pathogen if the antimicrobial compound reaches the concentrations at the site of infection necessary to inhibit growth of the pathogen. 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 a high dosage of drug can be used. this category also provides a buffer zone that prevents small uncontrolled technical factors from causing major discrepancies in interpretation. a report of resistant indicates that the antimicrobial is not likely to inhibit growth of the pathogen if the antimicrobial compound reaches the concentrations usually achievable at the infection site; other therapy should be selected. quality control standardized susceptibility test procedures require the use of laboratory controls to monitor and ensure the accuracy and precision of supplies and reagents used in the assay, and the techniques of the individuals performing the test. 1,2,3 standard cefaclor powder should provide the following range of mic values noted in table 2. for the diffusion technique using the 30 mcg disk the criteria in table 2 should be achieved. table 2: acceptable quality control ranges for cefaclor table 2: acceptable quality control ranges for cefaclor qc strain minimal inhibitory concentration (mcg/ml) zone diameter (mm) escherichia coli atcc 25922 1 – 4 23 – 27 haemophilus influenzae atcc 49766 1 – 4 25 – 31 staphylococcus aureus atcc 25923 -- 27 - 31 staphylococcus aureus atcc 29213 1 – 4 -- streptococcus pneumoniae atcc 49619 1 – 4 24 – 32