Antibiotics meningitis

The desired speed and duration of a therapeutic effed will also influence the development of the final drug product. The standard treatment of meningitis with antibiotics is via intravenous administration so as to achieve an immediate effed. 

Antimicrobials also can be classified as possessing bactericidal or bacteriostatic activity in vitro. Bactericidal antibiotics generally kill at least 99.9% (3 log reduction) of a bacterial population, whereas bacteriostatic antibiotics possess antimicrobial activity but reduce bacterial load by less than 3 logs. Clinically, bactericidal antibiotics may be necessary to achieve success in infections such as endocarditis or meningitis. A full discussion of the application of antimicrobial pharmacodynamics is beyond the scope of this chapter, but excellent sources of information are available.15... 

Development of resistance to P -lactam antibiotics, including penicillins and cephalosporins, has significantly impacted the management of bacterial meningitis. Approximately 17% of United States pneumococcal CSF isolates are resistant to penicillin, and 3.5% of CSF isolates are resistant to cephalosporins.26 The Clinical and Laboratory Standards Institute (CLSI) has set a lower ceftriaxone susceptibility breakpoint for pneumococcal CSF isolates (1 mg/L) than for isolates from non-CNS sites (2 mg/L). Increasing pneumococcal resistance to penicillin G... 

Empirical therapy for postoperative infections in neurosurgical patients (including patients with CSF shunts) should include vancomycin in combination with either cefepime, ceftazidime, or meropenem. Linezolid has been reported to reach adequate CSF concentrations and resolve cases of meningitis refractory to vancomycin.35 However, data with linezolid are limited. The addition of rifampin should be considered for treatment of shunt infections. When culture and sensitivity data are available, pathogen-directed antibiotic therapy should be administered. Removal of infected devices is desirable aggressive antibiotic therapy (including high-dose intravenous antibiotic therapy plus intraventricular vancomycin and/or tobramycin) may be effective for patients in whom hardware removal is not possible.36... 

The adjunctive agent dexamethasone has been shown to improve outcomes in selected patient populations with meningitis. Dexamethasone inhibits the release of proinflammatory cytokines and limits the CNS inflammatory response stimulated by infection and antibiotic therapy. 

Determine whether prophylaxis is indicated for close contacts of patients with CNS infections. Close contacts should be located for patients with suspected meningococcal or Hib meningitis. After consultation with the local health department, antibiotic prophylaxis should be provided promptly to these individuals to avoid secondary disease. 

Intrathecal (IT) Into the subarachnoid space between two of the membranes (meninges) separating the spinal cord from the vertebral column. This route is used for drugs that do not penetrate the blood-brain barrier, but which are required for their central action (e.g., antibiotics). Drugs can also be injected spinally (into the epidural space) for local anaesthesia or analgesia. 

Up to 50% of patients may receive antibiotics before a diagnosis of meningitis is made, delaying presentation to the hospital. Prior antibiotic therapy may cause the Gram stain and CSF culture to be negative, but the antibiotic therapy rarely affects CSF protein or glucose. 

Gram stain and culture of the CSF are the most important laboratory tests performed for bacterial meningitis. When performed before antibiotic therapy is initiated, Gram stain is both rapid and sensitive and can confirm the diagnosis of bacterial meningitis in 75% to 90% of cases. 

Meningitis caused by S. pneumoniae is successfully treated with 10 to 14 days of antibiotic therapy. Meningitis caused by N. meningitidis usually can be treated with a 7-day course. A longer course, >21 days, is recommended... 

Empiric antimicrobial therapy should be instituted as soon as possible to eradicate the causative organism (Table 36-2). Antimicrobial therapy should last at least 48 to 72 hours or until the diagnosis of bacterial meningitis can be ruled out. Continued therapy should be based on the assessment of clinical improvement, cultures, and susceptibility testing results. Once a pathogen is identified, antibiotic therapy should be tailored to the specific pathogen. 

With increased meningeal inflammation, there will be greater antibiotic penetration (Table 36-3). Problems ofCSF penetration maybe overcome by direct instillation of antibiotics by intrathecal, intracisternal, or intraventricular routes of administration (Table 36-4). 

Optimal antibiotic therapies for gram-negative bacillary meningitis have not been fully defined. Meningitis caused by Pseudomonas aeruginosa is initially treated with ceftazidime or cefepime, piperacillin + tazobactam, or meropenem plus an aminoglycoside, usually tobramycin. 

Before moving on, you should understand that not all drug interactions are bad. Sometimes we use them to our advantage. For example, it s common practice to combine antibiotics that attack bacteria in different ways when treating serious infections like pneumonia or meningitis. The two antibiotics work together to kill... 

Chloramphenicol, isolated in 1947, is a broad spectiarm antibiotic. It is rapidly absorbed from the gastrointestinal tract and hence can be given orally in case of typhoid, dysentery, acute fever, certain form of urinary infections, meningitis and pneumonia. Vancomycin and ofloxacin are the other important broad spectr-um antibiotics. The antibiotic dysidazirine is supposed to be toxic towards certain strains of cancer cells. 

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