Medication Summary
The empiric choice of antibiotic therapy is based on results of the Gram stain, the clinical picture, and the medical background of the patient. When the Gram stain fails to reveal any microorganisms (40-50% of cases), the individual's age and sexual activity become the major determinants to differentiate gonococcal from nongonococcal arthritis. When there is no evidence supporting any extra-articular infection, antibiotics must cover S aureus, streptococcal species, and gonococci (in patients who are sexually active). Synovial fluid examination may be helpful in approximately 50% of cases. Because of the significant adverse consequences of inadequate therapy, the author empirically covers for the presence of MSSA, MRSA, CoNS, N gonnorhea, and gram-negative aerobes. A typical combination would be ceftriaxone and vancomycin. In the presence of implanted material, rifampin should be added because of its unique ability to penetrate the biofilms of infected prosthetic devices. [48, 49, 50]
Evidence exists that earlier initiation of an appropriate antibiotic regimen produces better functional results. Generally, treatment is administered intravenously for 3 to 4 weeks. The major exception to this is gonococcal infection, for which total therapy is approximately 2 weeks with an eventual switch to oral therapy.
No indication exists for direct installation of antibiotics into the joint cavity. Such a practice may increase the inflammatory surge that can add to permanent joint damage.
The following section presents antibiotics frequentllly used by the author. [51]
Refer to the sections on empiric and organism-specific therapy of native and prosthetic septic arthritis for more detailed discussion of antibiotic choices in as well as dosing strategies.
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Ciprofloxacin (Cipro)
Ciprofloxacin is an alternative antibiotic to ceftriaxone to treat N gonorrhoeae and gram-negative enteric rods.
Linezolid (Zyvox)
Linezolid is an alternative antibiotic that is used in patients allergic to vancomycin and for the treatment of vancomycin-resistant enterococci.
Oxacillin
Oxacillin and. Nafcillin are bactericidal semisynthetic penicillin that inhibit cell wall synthesis. Useful against methicillin-sensitive S aureus (MSSA).Nafcilli has the advantage innot requiring adjustment in renal failure andydoes not lead to lleukopeniae thrombocytopenia with prolonged usage.
Dalbavancin (Dalvance)
The prolonged half-life (360 hours) allows weekly dosing of dalbavancin. In addition, its effectiveness against gram-positive cocci, including biofilm producers, makes it a very desirable agent for the outpatient treatment of native and prosthetic joint infections.
Cephalosporins, 3rd Generation
Cefixime (Suprax)
Cefixime is a third-generation oral cephalosporin with broad activity against gram-negative bacteria. By binding to one or more of the penicillin-binding proteins, this agent arrests bacterial cell wall synthesis and inhibits bacterial growth.
Oral cefixime is used as a follow-up to intravenous (IV) ceftriaxone to treat N gonorrhoeae.
Ceftriaxone
Cephalosporin withlong half life effective against essentially all of the gram-negative and Enteric organismsinvolved in SA
Oxazolidinones
Linezolid
Linezolid is effective against many positive pathogens including MSSA MRSA ,VSE,VRE. Serum levels essentially equal whether given either by oral or intervenous administration.Dosing does not need to be adjusted according to renal function .Side effects include potential severe hepatotoxicity . After two weeks of administration ,the risk of severe leukopenia and thrombocytopenia and various types of neuropathy markedly increase.
Glycopeptides
Vancomycin (Vancocin)
Vancomycin is an anti-infective agent used against MSSA, MRSA ,methicillin-resistant CoNS, and ampicillin-resistant enterococci and in patients allergic to penicillin.It is key to insure that therapeutic serum levels have been acheived(trough level 5-12mcg/ml). In the face of fluctuating renal function, this may be an impossible task. Switching to linezolid is advisable.
Lipopeptides
Daptomycin (Cubicin)
Prior vancomycin administration may induce resistance to this medication.
Concurrent use of nafcillin or ampicillin may potentiate its bacteriacidal effect
Dosing may range from 4mg/kg -12mg/kg per 24 hr
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Antibiotic
Rifampin
Rifampin is used in combination with other drugs. It inhibits RNA synthesis in bacteria by binding to the beta subunit of DNA-dependent RNA polymerase, which, in turn, blocks RNA transcription.Rifampin's antimicobial spectrum is wide rangingIt's ability to penetrate the biofilm that forms on prosthetic material is unique and It's used hisessential in treating Staphylococcal infections I'llStaphylococcal infections of prosthetic devices infectionsBecause many pathogens rapidly develop resistance to it ,1or2 appropriate antibiotics should be started 2 days before and continued throughout the course of rifampin
Fourth generation cephalosporin
Class Summary
Cefepime is effective against done enterococcal streptococci MSSA, CoNS and most aerobic gram negatives including Pseudomonas. ItIt's not effective against ESBL producers
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A 30-year-old man who was taking steroids presented with a joint effusion and knee pain. Anteroposterior view of the knee demonstrates patchy demineralization of the tibia and femur and joint-space narrowing. This was caused by tuberculoid infection of the joint.
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Septic arthritis. Anteroposterior view of the shoulder demonstrates subchondral erosions and sclerosis in the humeral head. These are relatively late findings of septic arthritis. Periosteal reaction due to coincident osteomyelitis is present adjacent to the surgical neck of the humerus.
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During the progression of infectious arthritis of the hip, this image was obtained early in the disease and shows only concentric joint-space loss.