Chapter 128. Pneumococcal Infections (Part 9)

Inpatient Therapy Pneumococcal pneumonia is readily treatable with β-lactam antibiotics. The conventional dosages shown in Table 128-5 are acceptable against intermediately resistant strains and against many or most fully resistant isolates. Recommended agents include ceftriaxone and cefotaxime. Ampicillin is also widely used, usually in the form of ampicillin/sulbactam. The likely efficacy of newer quinolones such as moxifloxacin, macrolides such as azithromycin, and clindamycin is discussed above. On the basis of in vitro considerations, vancomycin is likely to be uniformly effective against pneumococci; this drug or a quinolone should be used together with a third-generation cephalosporin for initial therapy in...
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Chapter 128. Pneumococcal Infections (Part 9) Chapter 128. Pneumococcal Infections (Part 9) Inpatient Therapy Pneumococcal pneumonia is readily treatable with β-lactam antibiotics. Theconventional dosages shown in Table 128-5 are acceptable against intermediatelyresistant strains and against many or most fully resistant isolates. Recommendedagents include ceftriaxone and cefotaxime. Ampicillin is also widely used, usuallyin the form of ampicillin/sulbactam. The likely efficacy of newer quinolones suchas moxifloxacin, macrolides such as azithromycin, and clindamycin is discussedabove. On the basis of in vitro considerations, vancomycin is likely to beuniformly effective against pneumococci; this drug or a quinolone should be usedtogether with a third-generation cephalosporin for initial therapy in a patient whois likely to be infected with a highly antibiotic-resistant strain. Patients who havehad a severe allergic reaction to penicillins or cephalosporins may be treated witha carbapenem (e.g., imipenem-cilastatin), a quinolone, or vancomycin. The failureof a patient to respond promptly should at least prompt consideration of drugresistance. Evidence for loculated infections (such as empyema) and/or othercauses of fever should be sought and addressed appropriately. Duration of Therapy The optimal duration of treatment for pneumococcal pneumonia isuncertain. Pneumococci begin to disappear from the sputum within several hoursafter the first dose of an effective antibiotic, and a single dose of procainepenicillin, which produces an effective antimicrobial level for 24 h, was curativein otherwise-healthy young adults in an era when all isolates were susceptible.Early in the antibiotic era, most physicians treated pneumococcal pneumonia for5–7 days. In the absence of data suggesting a need for longer treatment, youngerphysicians tend to treat the infection for 10–14 days. In the opinion of this author,a few days of close observation and parenteral therapy followed by an oralantibiotic—with the entire course of treatment continuing for no more than 5 daysafter the patient becomes afebrile—may be the best approach for treatingpneumococcal pneumonia, even in the presence of bacteremia. Cases with asecond focus of infection (e.g., empyema or septic arthritis) require longertherapy. Meningitis (Table 128-6) Pneumococcal meningitis should be treated initially withceftriaxone plus vancomycin. Equivalent doses of cefotaxime or cefepime may beused in place of ceftriaxone. The cephalosporin will be effective against most—but not all—isolates and will readily penetrate the blood-brain barrier; all isolateswill be susceptible to vancomycin, but this drug has a somewhat unpredictablecapacity to cross the blood-brain barrier. If the isolate is shown to be susceptibleor intermediately resistant, treatment can be continued with ceftriaxone, andvancomycin can be discontinued. If the organism is resistant, treatment with bothdrugs should be continued. A very few studies of experimental animals suggestbenefits of the addition of rifampin, but in vitro studies indicate antagonismbetween this drug and ceftriaxone or vancomycin; in the absence of data tosupport the practice in humans, this author does not recommend that rifampin beadded. Imipenem may be used in place of the cephalosporin in patients who havehad life-threatening allergic reactions to β-lactam antibiotics. The total duration oftherapy for pneumococcal meningitis is 10 days. A recent study demonstratedclear benefit from the addition of glucocorticoids (Chap. 376). Table 128-6 Treatment of Pneumococcal Meningitis Circumstance Appropriate Coursea Diagnosis of Treat with ceftriaxone, 2 g q12h, pluspneumococcal meningitis; vancomycin, 500 mg q6h, until antibioticantibiotic susceptibility unknown susceptibility of organism is known. Susceptibility results Continue treatment with ceftriaxoneavailable alone if organism is susceptible or intermediate; continue both ceftriaxone and vancomycin if organism is resistant. Life-threatening penicillin Treat with imipenem, 500 mg q6h, ratherallergy than a β-lactam antibiotic. a Treatment should be administered for 5–7 days after defervescence or for atotal of 10 days. Endocarditis Pneumococcal endocarditis is associated with rapid destruction of heartvalves. Pending results of susceptibility studies, treatment should be initiated withceftriaxone or cefotaxime; if the prevalence of highly resistant strains increases, itmight be prudent to add vancomycin until results of susceptibility studies areavailable. In vitro, aminoglycosides are somewhat synergistic and rifampin orquinolones are antagonistic with β-lactams against pneumococci; there is no clearevidence from in vivo studies that adding any of these antibiotics to the regimen isbeneficial. Other Therapeutic Modalities Addition of drotrecogin, an activated protein C preparation, may bebeneficial in treating patients with severe pneumococcal sepsis. Glucocorticoidsand agents that block the action of TNF-α, IL-1, or platelet-activating factor haveconferred no benefit.