Infectious Disease Compendium

Prosthetic Joint Infection

Diagnosis

2012 IDSA Guidelines

They can be acute or chronic, they can be in the joint space or in the stem (often presenting with pain and loosening), they can be hematogenous or acquired at the time of surgery.

Chronic infections tend to be stem infections and present just with progressive pain, night pain, and joint loosening (especially if occurring in the first one to 2 years). CRaP and ESR are nice if elevated (both up to have an 86% chance of infection), but no test is perfect. If a preop tap for revision has a WBC > 1700 or more than 65% PMN's there is a >95% chance there is an infection (PubMed).

If three intra-op cultures are positive it also suggests a high likelihood of infection. Duh.

There are a variety of synovial fluid markers for the diagnosis of periprosthetic joint infection including C reactive protein, leukocyte esterase, interleukin6, interleukin1β, α-defensin, and interleukin 17 (PubMed). They are all good with perhaps a nod to alpha defensin as best of breed.

A positive alpha-defensin from the joint fluid is reported to have a sensitivity of 100%, a specificity of 98%, a positive predictive value of 96% and a negative predictive value of 100% (PubMed).  My rule of thumb is that a test is half as good in the real world but still looks to be a good test.

On frozen section >10 PMN's per high powered field means infection (PubMed).

And on histopathology, the weirdly precise 23 PMNS is the cutoff, with a "sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.7%, 90.0%, 96.7%, 52.9% and 81.1% respectively for the Morawietz classification, and 82.0%, 90.0%, 96.9%, 57.1% and 83.7% respectively for the 23 NG threshold (PubMed).

"Postoperative soft-tissue gas present on radiography performed 14 days or more after TKA is predictive of early PJI and is associated with a wider spectrum of microorganisms (PubMed)."

Epidemiologic Risks

Intra-operative acquisition. Often the source is not the patient but the OR staph, er, I mean staff. And I wonder how many were due to not scrubbing the hub before injections.

Bacteremia (S. aureus has a ~34% chance of seeding a prosthetic joint. Really (PubMed).

"Development of a PJI was most common for Staphylococcus aureus (21% of bacteremias led to a PJI) and beta-hemolytic streptococci (21%), whereas it was rare for gram-negative bacteria (1.3%). Having ≥2 bacteremias during the study period increased the risk of developing a PJI. The risk for developing a PJI was highest for bacteremias occurring within a year of previous surgery (Pubmed). Another study puts it in the same ballpark, 19% (Pubmed).

Of the streptococci, Group B has the worst prognosis (PubMed).

Asymptomatic white cells in the urine is not a risk for infection and is NOT a reason to postpone surgery (PubMed).

And are antibiotics necessary in hip arthroplasty with asymptomatic bacteriuria? Spoiler alert: No (PubMed). Although asymptomatic bacteriuria (ASB) is a risk for prosthetic joint infection, it is a marker since the organism in the joint is NOT in the one in the urine and treating the ASB does nothing (PubMed).

P. avidum lives in the groin of obese patients and from there infect prosthetic hips (PubMed).

Microbiology

Acute joint: S. aureus, coagulase-negative Staphylococcus (#1 cause), Streptococci, occasionally gram-negative enteric organisms (like E. coli).

"Compared with non-obese patients, obese patients had higher rates of polymicrobial infections with more often involvement of Enterococcus species. Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (Pubmed).  I will note that the Proteus is something I have seen as well.

Chronic stem: S. aureus, coagulase-negative Staphylococcus (#1 cause), gram-negative enteric organisms (like E. coli), and Propionibacterium acnes for shoulders and P. avidum for hips (PubMed).

A weird cause of prosthetic joint loosening "Encephalitozoon cuniculi should be considered as a cause of osteolysis in hip periprosthetic tissue, leading to a loss of implant stability (PubMed)."

If you have a chronic infection/late and the initial operative cultures are negative, have micro hold the cultures for two weeks (most labs will only hold the cultures for 5 days) and you will increase the yield, predominantly coagulase-negative Staphylococcus and Propionibacterium (PubMed)(PubMed).

For culture-negative infections, techniques to look for DNA may find the pathogens 10% of the time (PubMed).

Empiric Therapy

GET CULTURES. It may behoove you to hold the cultures for 14 days as it increases the yield of fastidious organisms like Propionibacterium (PubMed). AFTER cultures are obtained, vancomycin +/- third-generation cephalosporins.

No debridement, no cure. Know debridement, know cure.

If it is an acute joint infection AND streptococcal or methicillin-susceptible S. aureus AND you debride the joint with poly exchange (and what is a parrot doing in a joint?) AND treat with 6 weeks (some suggest 2-3, I am not that convinced) of an anti-staph beta-lactam IV PLUS rifampin (450 mg po bid) AND follow up with 6 months of po quinolone PLUS rifampin you may salvage the joint.

The rifampin is key, despite all the side effects of the medication. One study with small numbers of patients, monotherapy with moxifloxacin for three months had an 80% success rate. I am sticking with combo therapy (PubMed).

High dose daptomycin (8-10 mg/kg) plus rifampicin is also effective (PubMed)(PubMed); maybe push the daptomycin to 10/mg/kg but except a 50% failure rate (PubMed).

Clindamycin and rifampin (PubMed) is also an effective combination. I would still consider it only if there were no other options (PubMed).

Debridement with joint retention has about a 55% chance of working in one large retrospective study (PubMed); oddly there was no long term difference between MRSA and MSSA infection for long term success. I would have bet a worser outcome for MRSA.

"...eradication rates as follows: MSSA (92.6%), MSSE (95.2%), MRSA (80%), and MRSE (54.2%). MRSE showed a significantly lower rate of patients graded as "definitively free of infection" as compared to patients with infections caused by MSSA, MSSE, and MRSA (PubMed)."

If debridement and retention fail, take out the joint, treat 6 weeks with IV, wait a bit (I find the duration is surgeon dependent and there is no data to guide us) then a new hip. In one retrospective study, those who received at least 14 days po antibiotics after re-implantation had fewer infections (PubMed).

There is more data to support better outcomes with a 2 stage procedure over a one-stage (PubMed).

Much to my surprise, in a retrospective study ceftriaxone, was equal to oxacillin for MSSA infections (PubMed).

With aggressive debridement, IV therapy and long term po with a quinolone, you might salvage (75% probability) gram-negative infections (PubMed). If it is ciprofloxacin resistant, the chance of salvage lessens (PubMed).

Is IV therapy mandated? Maybe not if you can use oral agents with good bioavailability and there is good debridement (PubMed).

4 weeks after joint removed is no worse then 6 and po works fine(Pubmed).

How long to give oral therapy is not clear. At least 3 months (Pubmed).

Lifetime suppression, especially if that lifetime is not going to be all that long, may be warranted; the goal is function more than cure.  Suppression increases the chance of keeping the joint long term even with S. aureus (PubMed). Pick an antibiotic that is inexpensive and non-toxic. In one series doxycycline was effective (PubMed).

For Streptococcus, 28 days iv followed by three months of oral resulted in an 80% cure rate (PubMed) with no long term suppression.

Cure without rifampin is overall maybe 60% (14-83); chance with rifampin is an extra 10-20% in the salvage rate.

Even with streptococcal infections rifampin increases cure, which surprised me (Pubmed)(PubMed). I would have thought rifampin would add nothing for streptococci. And not a finding in all studies (PubMed).

Despite the long tradition of using antibiotic spacers, the data confirming the use of antibiotics in spacers is still of poor quality (PubMed). And I have seen several cases of aminoglycoside toxicity from spacers (PubMed) and there are cases with vancomycin as well (PubMed).

Pearls

If MRSA, poor soft tissue (sinus tract), loose joint (a stem infection is harder to cure than joint infection), diabetic, or smoker, probably not salvage the joint, but you always try, don't you?

Prosthetic joint infections can be particularly difficult to treat when S. aureus makes small colony variants.

Chronic suppression works and patients who never stop their po antibiotics are more likely to keep their joint.

Don't even try and salvage a gram-negative rod prosthetic joint infection. It will not work (PubMed).

There are no reason the treat asymptomatic bacteria in the urine preop: it does NOT decrease the risk of infection, nor does antibiotics for GU procedure (PubMed).

If the prosthetic joint is infected with Enterococcus, monotherapy is equal to the combination (PubMed). If the infection is in the stem of the prosthetic joint, rather than the joint space, a medical cure is probably impossible.

I prefer to take out the joint, give six weeks of IV therapy, wait a month, and if the joint is not infected, replace the joint. I know there is data for primary exchange, but the risk if repeat for 3 months, could be a death sentence.

Having a positive culture at reimplantation, which occurred in an amazing 17% (I can remember two in my storied career) increases failure rate (PubMed).

"In a 2-stage exchange procedure for PJI, adding a glycopeptide to the cement spacer reduces the rate of positive cultures during reimplantation and is associated with a lower failure rate due to CoNS afterward(Pubmed)".

Sometimes it is elected to keep the spacer in rather than another surgery due to patient co-morbidities. In one series, about 10% got infected, especially if there was a sinus tract and suppressive antibiotics didn't do much (PubMed).

Rants

While suggested by many authorities, there is no data that suggests prophylactic antibiotics are effective in preventing prosthetic joint infections if continued > 24 hours. It only breeds resistance. Actually (the favorite word of a skeptic when beginning a sentence), you do NOT NOT NOT need to do dental prophylaxis for joints. There is a study (PubMed), and I quote, "Dental procedures were not risk factors for subsequent total hip or knee infection. The use of antibiotic prophylaxis prior to dental procedures did not decrease the risk of subsequent total hip or knee infection." Ha!

Curious Cases

Relevant links to my Medscape blog

Any Bug, Any Place

Working with minimal data

A Case From One of the Country's Best

Toxic See Mint

Late Failure

A Bit of Whinging Then a Case

Weird PJI. Part One

Weird PJI 2: Electric Boogaloo

Bog Body

Slow Joint

Frugal for Infection

Heavy Metal MoM

It Doesn't Work

Last Update: 01/18/20.