nsidered 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. bacteriology studies to determine the causative organisms and their susceptibility to ampicillin should be performed. therapy may be instituted prior to the results of susceptibility testing.

agement, including intubation, should also be administered as indicated. pseudomembranous colitis has been reported with nearly all antibacterial agents, including ampicillin, and may range 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 clinically effective against c. difficile colitis.

intestinal tract infections , the usual dose is 100 mg/kg/day total, qid in equally divided and spaced doses. for respiratory infections, the usual dose is 50 mg/kg/day total, in equally divided and spaced doses three to four times daily. doses for children should not exceed doses recommended for adults. all patients, irrespective of age and weight: larger doses may be required for severe or chronic infections. although ampicillin is resistant to degradation by gastric acid, it should be administered at least one-half hour before or two hours after meals for maximal absorption. except for the single dose regimen for gonorrhea referred to above, therapy should be continued for a minimum of 48 to 72 hours after the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. in infections caused by hemolytic strains of streptococci, a minimum of 10 days’ treatment is recommended to guard against the risk of rheumatic fever of glomerulonephritis (see precautions–laboratory tests ). in the treatment of chronic urinary or gastrointestinal infections, frequent bacteriologic and clinical appraisal is necessary during therapy and may be necessary for several months afterwards. stubborn infections may require treatment for several weeks. smaller doses than those indicated above should not be used.

rash, pruritus, urticaria, erythema multiforme, and an occasional case of exfoliative dermatitis. anaphylaxis is the most serious reaction experienced and has usually been associated with the parenteral dosage form of the drug. note: urticaria, other skin rashes, and serum sickness-like reactions may be controlled by antihistamines, and, if necessary, systemic corticosteroids. whenever such reactions occur, ampicillin should be discontinued unless, in the opinion of the physician, the condition being treated is life-threatening, and amenable only to ampicillin therapy. serious anaphylactoid reactions require emergency measures (see warnings ). liver: moderate elevation in serum glutamic oxaloacetic transaminase (sgot) has been noted, but the significance of this finding is unknown. hemic and lymphatic systems: anemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported during therapy with penicillins. these reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena. other adverse reactions that have been reported with the use of ampicillin are laryngeal stridor and high fever. an occasional patient may complain of sore mouth or tongue as with any oral penicillin preparation.

/ml. microbiology mechanism of action ampicillin is similar to penicillin in its bactericidal action against susceptible bacteria during the stage of active multiplication. it acts through the inhibition of cell wall biosynthesis that leads to the death of the bacteria. mechanism of resistance resistance to ampicillin is mediated primarily through enzymes called beta-lactamases that cleave the beta-lactam ring of ampicillin, rendering it inactive. antimicrobial activity ampicillin has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections, as described in the indications and usage section. gram-positive bacteria enterococcus spp. staphylococcus spp. (non-penicillinase-producing) streptococcus pneumoniae streptococcus pyogenes viridans group streptococci gram-negative bacteria escherichia coli haemophilus influenzae (non-penicillinase-producing) neisseria gonorrhoeae neisseria meningitidis proteus mirabilis salmonella spp. shigella spp. 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 concentration (mic) less than or equal to 0.12 mcg/ml for ampicillin. however the efficacy of ampicillin in treating clinical infections due to these bacteria has not been established in adequate and well-controlled trials. gram-positive bacteria bacillus anthracis corynebacterium xerosis anaerobic bacteria clostridium spp. susceptibility test methods when available, the clinical microbiology laboratory should provide in vitro susceptibility test results for antimicrobial drugs used in local hospitals and practice areas 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 antimicrobial drug product 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 test method 1,3 (broth and/or agar). the mic values should be interpreted according to the criteria provided in table 1. diffusion techniques quantitative methods that require measurement of zone diameters can 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 10 mcg ampicillin to test the susceptibility of bacteria to ampicillin. the disk diffusion interpretive criteria are provided in table 1. susceptibility to ampicillin of staphylococcus spp., may be inferred by testing penicillin. 3 perform test(s) to detect beta-lactamase production on staphylococci for which the penicillin mics are ≤ 0.12 mcg/ml or zone diameters are ≥ 29 mm before reporting isolates as penicillin susceptible. rare isolates of staphylococci that contain genes for beta-lactamase production may appear negative by beta-lactamase tests. consequently, for serious infections requiring penicillin therapy, laboratories should perform mic tests and beta-lactamase testing on all subsequent isolates from the same patient. pcr testing of the isolate for the bla z beta-lactamase gene may be considered. 3 susceptibility to ampicillin of streptococcus pneumoniae (non-meningitis isolates), may be inferred by testing penicillin or oxacillin. non-meningitis isolates with a penicillin mic ≤0.06 mcg/ml or oxacillin zone size ≥20 mm can be considered susceptible to ampicillin. 3 table 1: susceptibility test interpretive criteria for ampicillin pathogen minimum inhibitory concentrations (mcg/ml) disk diffusion (zone diameters in mm) s i r s i r s = susceptible; i = intermediate; r = resistant enterobacteriaceae ≤8 16 ≥32 ≥17 14-16 ≤13 haemophilus influenzae the majority of isolates of h. influenzae that are resistant to ampicillin produce a tem-type beta-lactamase. in most cases, a direct beta-lactamase test can provide a rapid means of detecting resistance to ampicillin. 3 ≤1 2 ≥4 ≥22 19-21 ≤18 enterococcus penicillin or ampicillin resistance among enterococci due to beta-lactamase production has been reported very rarely. penicillin or ampicillin resistance due to beta-lactamase production is not reliably detected with routine disk or dilution methods, but is detected using a direct, nitrocefin-based beta-lactamase test. because of the rarity of beta-lactamase-positive enterococci, this test need not be performed routinely, but can be used in selected cases. a positive beta-lactamase test predicts resistance to penicillin as well as amino- and ureidopenicillins. 3 spp. ≤8 - ≥16 ≥17 - ≤16 neisseria meningitidis ≤0.12 0.25-1 ≥2 - - - viridans group streptococci ≤0.25 0.5-4 ≥8 streptococcus pyogenes susceptibility testing of ampicillin need not be performed routinely because nonsusceptible isolates of beta-hemolytic streptococci are extremely rare, and have not been reported for s. pyogenes. if testing is performed, any beta-hemolytic streptococcus isolate that is found to be non-susceptible should be re-identified retested, and if confirmed, reported to the public health laboratory. 3 ≤0.25 - - ≥24 - - a report of susceptible indicates that the antimicrobial is likely to inhibit growth of the pathogen if the antimicrobial drug reaches the concentration usually achievable at the site of infection. 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. 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 concentration usually achievable at the infection site; other therapy should be selected. quality control standardized susceptibility test procedures require 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 ampicillin powder should provide the following range of mic values noted in table 2. for the diffusion technique using the 10 mcg ampicillin disk, the criteria in table 2 should be achieved. table 2: acceptable quality control ranges for ampicillin 3 qc strain minimum inhibitory concentration (mcg/ml) zone diameter ( mm) * atcc = american type culture collection escherichia coli atcc* 25922 2 - 8 15 - 22 enterococcus faecalis atcc 29212 0.5 - 2 haemophilus influenzae atcc 49247 2 - 8 13 - 21 klebsiella pneumoniae atcc 700603 >128 staphylococcus aureus atcc 29213 0.5 - 2 staphylococcus aureus atcc 25923 27 - 35 streptococcus pneumoniae atcc 49619 0.06 – 0.25 30 - 36

ed. skipping doses or not completing the full course of therapy may: (1) decrease the effectiveness of the immediate treatment, and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by ampicillin or other antibacterial drugs in the future. repackaged by / distributed by: remedyrepack inc. 625 kolter drive, indiana, pa 15701 (724) 465-8762