Infection antimicrobial therapy

Grayson ML. Diabetic foot infections Antimicrobial therapy. Infect Dis Clin North Am 1995 9 143-161. 

Bacterial cultures should be obtained prior to antimicrobial therapy in patients with a systemic inflammatory response, risk factors for antimicrobial resistance, or infections where diagnosis or antimicrobial susceptibility is uncertain. 

Many areas of the human body are colonized with bacteria— this is known as normal flora. Infections often arise from one s own normal flora (also called an endogenous infection). Endogenous infection may occur when there are alterations in the normal flora (e.g., recent antimicrobial use may allow for overgrowth of other normal flora) or disruption of host defenses (e.g., a break or entry in the skin). Knowing what organisms reside where can help to guide empirical antimicrobial therapy (Fig. 66-1). In addition, it is beneficial to know what anatomic sites are normally sterile. These include the cerebrospinal fluid, blood, and urine. 

While selection of antimicrobial therapy may be a major consideration in treating infectious diseases, it may not be the only therapeutic intervention. Other important therapies may include adequate hydration, ventilatory support, and other supportive medications. In addition, antimicrobials are unlikely to be effective if the process or source that leads to the infection is not controlled. Source control refers to this process and may involve removal of prosthetic materials such as catheters and infected tissue or drainage of an abscess. Source-control considerations should be a fundamental component of any infectious diseases treatment. It is also important to recognize that there may be many different antimicrobial regimens that may cure the patient. While the following therapy sections... 

Most initial antimicrobial therapy is empirical because cultures usually have not had sufficient time to identify a pathogen. Empirical therapy should be based on patient- and antimicrobial-specific factors such as the anatomic location of the infection, the likely pathogens associated with the presentation, the potential for adverse effects in a given patient, and the antimicrobial spectrum of activity. Prompt initiation of appropriate therapy is paramount in hospitalized patients who are critically ill. Patients who receive initial antimicrobial therapy that provides coverage against the causative pathogen survive at twice the rate of patients who do not receive adequate therapy initially.8... 

Patients with a history of recent antimicrobial use may have altered normal flora or harbor resistant organisms. If a patient develops a new infection while on therapy, fails therapy, or has received antimicrobials recently, it is prudent to prescribe a different class of antimicrobial because resistance is likely. Previous hospitalization or health care utilization (e.g., residing in a nursing home, hemodialysis, and outpatient antimicrobial therapy) are risk factors for the acquisition of nosocomial pathogens, which are often resistant organisms. 

Baddour LM, Wilson WR, Bayer AS, et al. Infective endocarditis Diagnosis, antimicrobial therapy, and management of complications a statement for healthcare professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, and the Councils on Clinical Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association endorsed by the Infectious Diseases Society of America. Circulation 2005 111(23) 394M34. 

Prompt initiation of intravenous high-dose cidal antimicrobial therapy directed at the most likely pathogen (s) is essential due to the high morbidity and mortality associated with CNS infections parenteral (intravenous) therapy is administered for the full course of therapy for CNS infections to ensure adequate CSF penetration throughout the course of treatment. 

Components of a monitoring plan to assess the efficacy and safety of antimicrobial therapy of CNS infections include clinical signs and symptoms and laboratory data (such as CSF findings, culture, and sensitivity data). 

A high index of suspicion should be maintained for patients at risk for CNS infections. Prompt recognition and diagnosis are essential so that antimicrobial therapy can be initiated as quickly as possible. A medical history (including risk factors for infection and history of possible recent exposures) and... 

Brain abscesses are localized collections of pus within the cranium. These infections are difficult to treat due to the presence of walled-off infections in the brain tissue that are hard for some antibiotics to reach. In addition to appropriate antimicrobial therapy (a discussion of which is beyond the scope of this chapter), surgical debridement is often required as an adjunctive measure. Surgical debridement also may be required in the management of neurosurgical postoperative infections. 

Monitoring of laboratory tests is important in patients receiving treatment for CNS infections. Monitor CSF and blood cultures so that antimicrobial therapy can be tailored to the eti-ologic organisms. Follow-up cultures may be obtained to prove... 

Every patient receiving antimicrobial therapy for skin and soft tissue infections must be monitored for efficacy and safety. Efficacy typically is manifested by reductions in temperature, white blood cell count, erythema, edema, and pain that begin within 48 to 72 hours. To ensure safety, dose antibiotics according to renal and hepatic function as appropriate, and monitor for and minimize adverse drug reactions, allergic reactions, and drug interactions. 

The severity of a patient s infection, based on the PEDIS scale, guides the selection of empirical antimicrobial therapy. While most patients with grade 2 diabetic foot infections can be treated as outpatients with oral antimicrobial agents, all grade 4 and many grade 3 infections require hospitalization, stabilization of the patient, and broad-spectrum IV antibiotic therapy.31... 

Bacterial colonization of pressure sores is common. Because infection impairs wound healing and may require systemic antimicrobial therapy, the clinician must be able to distinguish it from colonization. Table 70-8 describes the clinical presentation of infected pressure sores. 

Surgical intervention has become an integral therapy in combination with pharmacologic management of IE. Valve replacement is the predominant intervention, and it is used in a minimum of 25% for all cases of IE.1 Surgery may be indicated if the patient has unresolved infection, ineffective antimicrobial therapy (often associated with fungal IE), more... 

Baddour LM, Wilson WR, Bayer AS, et al. Infective endocarditis Diagnosis, antimicrobial therapy, and management of complications. American Heart Association scientific statement. Circulation 2005 111 e394—433. 

Risk factors for salmonellosis include extremes of age, alteration of the endogenous bowel flora of the intestine (e.g., as a result of antimicrobial therapy or surgery), diabetes, malignancy, rheumatologic disorders, human immunodeficiency virus (HIV) infection, and therapeutic immunosuppression of all types. 

Sustained bacteremia or deep focus of infection in a previously normal host that responds to antimicrobial therapy... 

Patients with GI infections should be evaluated for resolution of GI symptoms, as well as any related systemic signs and symptoms. If antimicrobial therapy was used, completion of the course of therapy should be assessed. Documented clearance of the offending microorganism is not necessary. 

Cultures of secondary intraabdominal infection sites generally are not useful for directing antimicrobial therapy. Treatment generally is initiated on a presumptive or empirical basis. 

The treatment of intraabdominal infection most often requires the coordinated use of three major modalities (1) prompt drainage, (2) support of vital functions, and (3) appropriate antimicrobial therapy to treat infection not eradicated by surgery. Antimicrobials are an important adjunct to drainage procedures in the treatment of secondary intraabdominal infections however, the use of antimicrobial agents without surgical intervention usually is inadequate. For most cases of primary peritonitis, drainage procedures may not be required, and antimicrobial agents become the mainstay of therapy. 

Whether diagnosed with primary or secondary peritonitis, monitor the patient for relief of symptoms. Once antimicrobials are initiated and the other important therapies described earlier are used, most patients should show improvement within 2 to 3 days. Successful antimicrobial therapy with resolution of infection will result in decreased pain, manifested as resolution of abdominal guarding and decreased use of pain medications over time. The patient should not appear in distress, with the exception of recognized discomfort and pain from incisions, drains, and a nasogastric tube. 

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