Antibiotic Treatment

The choice of antibiotic
The selection of the antibiotic for the treatment of the infection around the total joint depends on the sensitivity of the bacterial strain that caused the infection.
Unfortunately, often there is more than one bacterial strain found in the infected joint.
Moreover, in about 10 -20 per cent of all total joint infections, no bacteria grow in the sample taken from the infected joint, although there are other obvious signs of infection present.

It is also possible that the bacteria are there, in the samples taken, but they will not grow because the bacteriologist used inappropriate technique for bacterial cultivation, or because the surgeon took few samples from the operation wound.
Consultation with the infectious-disease specialist is then extremely valuable. He will help to choose the appropriate antibiotic and to monitor the efficacy and the safety of the established antibiotic therapy.
When the bacteria causing the infection is not known, the surgeon usually relies on the past experience. The surgeon supposes that the as yet unknown bacterial strain has the same sensitivity to antibiotics as the majority of bacterial strains recovered from the postoperative infections in the past; most surgeons use a cephalosporin antibiotic.

The duration of antibiotic therapy
after revision operation varies widely, depending on the character of the infection and the surgeon. Most surgeons use six weeks period of antibiotic treatment after revision operation, and choose the dose of antibiotic that according to the laboratory tests will kill 99% of infecting bacteria. Short antibiotic treatment causes a recurrence of the infection.

Antibiotic suppression
is a term denoting a long term treatment with antibiotics of patients whose infected prosthesis was not removed.
The long term use of suppressive antibiotics should inhibit the growth of bacteria around the infected prosthesis. The value of the suppressive treatment is discussed.
It may be used in patients who may not tolerate a revision operation for medical reason, for patients who were infected with “kind” bacteria that were sensitive to several antibiotics, or for patients who refused yet another surgery. Statistics show that in these patients the infection was suppressed for 4 years in about 60 % of all cases
In many patients, however, the continuous antibiotic therapy provokes adverse effects, such as an allergy against the antibiotic. Such long antibiotic therapy also provokes emergence of bacterial strain resistant to antibiotics.

Certain antibiotics may cause a possibly lethal bowel inflammation (necrotising colitis) with prolonged administration. The first sign is severe diarrhoea, be observant of it.

References:

• Garvin KL et al J Bone Joint Surg-Am 1995; 77-A:1576 – 88