Artificial Total Joint Replacement Infection

Periprosthetic joint infection (PJI) is a serious complication after total joint arthroplasty. The incidence of PJI is generally low, with contemporary rates ranging from 0.57% to 2.8% for total shoulder arthroplasty, total hip arthroplasty (THA), and total knee arthroplasty (TKA). However, arthroplasty is a common surgical procedure with 800,000 or more THA and TKA procedures performed in the United States each year. As a result, the number of PJI cases encountered is significant despite the generally low incidence.

The mainstays of treatment of PJI are antimicrobial therapy and surgery (debridement, implant removal, or amputation). In addition to the morbidity of the infection, extended hospitalization, and further surgery associated with PJI, there is also a significantly greater mortality. Patients undergoing revision arthroplasty for PJI have an increased mortality at 1 year of 10.6% versus 2.0% when compared with revision arthroplasty for aseptic failures.

Cases of PJI following TKA are associated with increased economic costs, with PJI being the most common indication for revision of a TKA. One study showed that PJI had a higher mean annual cost of $116,383 compared with $28,249 in controls. A study of Medicare reimbursements demonstrated a 2.2-fold higher reimbursement for PJIs compared with uninfected controls.

Artificial Heart Valve Infection

Endocarditis is a term used to describe inflammation of the endocardial lining of the heart. Most endocarditis is infectious in nature. The incidence of infectious endocarditis (IE) is low, ranging from 3 to 8 cases per 100,000 persons in industrialized countries. Patients with prosthetic valves are at higher risk for endocarditis; however, 50% of IE develops in patients with no known cardiac disease. Prosthetic valve endocarditis (PVE) occurs in 1% to 6% of prosthetic valves with an incidence of 0.3 to 1.2 per patient-year.

There is significant morbidity with IE, including the destruction of cardiac tissues and valves, congestive heart failure, embolic events (particularly cerebral complications), the need for extended hospitalization, and the frequent need for surgery for debridement and reconstruction of cardiac structures. Given this, the mortality of PVE is high, with an in-hospital mortality ranging from 14% to 75%. Unfortunately, neither the incidence nor the mortality of IE has decreased in the past several decades despite advancements in diagnosis, antimicrobial agents, and surgical techniques.

Given the associated morbidity, mortality, and costs of PJI and PVE-IE, it is no wonder there is an interest in preventing these infections.

Urologic Procedures

Because bacteremia is the mechanism by which artificial joints and heart valves are thought to be seeded during later surgical procedures, it is important to understand the incidence of bacteremia with urologic procedures. Interpretation of many studies in this regard is difficult because the rates of sepsis are often reported without associated blood culture data and, therefore, the overall rates of symptomatic and asymptomatic bacteremia are often not known. A meta-analysis examining the use of antibiotics for transurethral procedures (eg, cystoscopy, transurethral resection of prostate, and transurethral resection of bladder tumor) demonstrated bacteremia rates of 6.1% without antibiotics and 2.1% with antibiotic use.

In patients with negative urine and blood cultures undergoing urodynamics without prophylactic antibiotics, 7% demonstrated bacteremia on immediate postprocedure blood cultures. The organisms were Escherichia coli, Pseudomonas , and coagulase-negative staphylococci. Two patients had preprocedural positive urine cultures with E coli and both had postprocedure E coli bacteremia. No patients were symptomatic or needed treatment.

In a randomized study of 50 transrectal prostate biopsies completed without periprocedural antibiotics, bacteremia was found in 28% of subjects not receiving a prebiopsy enema and 4% of those receiving an enema. Blood and urine cultures were taken 15 minutes after the biopsy. The rates of prebiopsy bacteriuria were 44% in the no enema and 52% in the enema group. Both groups had a 44% rate of postbiopsy bacteriuria. Most of the urine cultures had bacterial growth of less than 10,000 colony-forming units (CFU)/mL and none were greater than 50,000 CFU/mL. Only 1 of the 8 subjects with bacteremia (12.5%) was symptomatic necessitating treatment with oral ciprofloxacin. This subject’s blood culture grew E coli . Other organisms isolated from the blood cultures were one each of Staphylococcus , Streptococcus , diphtheroids, Bacteroides fragilis, Propionibacterium , and Gemella morbillorum , and 2 each of Enterobacter and gram-positive rods not otherwise specified. Only one man had the same organism on prebiopsy urine culture as on blood culture and none had the same organism in postbiopsy urine and blood cultures. In studies using periprocedural antibiotic prophylaxis, the rates of bacteremia with transrectal prostate biopsy are often equal to or less than 1%; however, the rates of fluoroquinolone-resistant bacteria are increasing.

The use of intravesical bacillus Calmette-Guérin (BCG) in patients with prosthetic devices seems to be safe. A phase II trial of BCG plus interferon α-2b therapy for nonmuscle invasive bladder cancer included 13 subjects with artificial heart valves and 43 with orthopedic hardware. It showed that these subjects were no more likely to develop a fever compared with the general population and there were no infectious complications of the prosthetics. Rates of bacteremia posttreatment are not known, however.

A summary of urologic procedures considered by the American Urologic Association (AUA) to be at increased risk for bacteremia is summarized in Box 1 .

Bacteremia from Other Sources

The risk of bacteremia is not isolated to urologic procedures. Procedures involving the gastrointestinal tract also pose a risk. For example, the rate of bacteremia associated with colonoscopy is 2% to 16%. Dental procedures have potentially high rates of bacteremia. For a tooth extraction or gingivectomy, the median incidence rate of bacteremia is about 65% or higher. Daily activities also can be a source of bacteremia, particularly those involving the oral cavity. The median incidence of bacteremia is about 4% for chewing and 18% for toothbrushing. These frequent events may be more significant sources of bacteremia during a person’s lifetime compared with occasional surgical procedures.

Given the risk of surgical procedures inducing bacteremia and the potential for hematogenous spread of this bacteria to prosthetic implants, various organizations have developed guidelines to help clinicians with decision making regarding the use of antibiotic prophylaxis in this setting.