The
NNIS guidelines recommend preoperative prophylactic antimicrobial therapy for
procedures
with
an estimated SSI risk >1% based upon the NNIS score.
Prophylactic
antimicrobial therapy should be strongly considered for:
(i) any clean-contaminated procedure,
(ii) any clean procedure in a patient with an NNIS score >1
(iii) an immunocompromisedpatient,
(iv) when any prosthetic material is inserted,
(v) when the operative area contains high bacterial counts, such
as the axilla or scrotum.
NNIS
Score Risk of SSI (%)
0: 1.5
1: 2.9
2: 6.8
3: 13.0
Note: Because it is difficult to estimate an individual
patient’s
risk of SSI based on traditional risk factors
the NNIS score
was developed to consider the interaction between multiple
risk factors and
provide individualized SSI risk assessments. Estimates are based on over 84,000
procedures with
2376 documented SSIs. To calculate NNIS score, contaminated and dirty wounds
are
given 1 point,
an ASA score of III or greater is given 1 point, and length of procedure
>75th percentile
is given 1
point.
Abbreviations: NNIS, National Nosocomial Infection Surveillance System;
SSI, surgical site infection.
Timing
of antimicrobial prophylaxis administration is critical. A large study by Stone
et al. found that the lowest SSI risk occurred when therapy was initiated within
one hour of surgery.
Patients
who received therapy after the incision had nearly the same risk as patients
who
did
not receive prophylaxis. More recent data corroborate the conclusion that
timely preoperative
antimicrobial
administration can reduce SSI rates. These and other observations
demonstrate
the importance of obtaining therapeutic serum antimicrobial levels before the
surgical
incision
and exposure to bacteria.
Current
guidelines suggest that prophylactic antimicrobials should be redosed
appropriately for lengthy procedures and should stop within 24 hours of surgery.
Recent
data support prophylactic antimicrobial therapy for trans-scrotal surgery based
on
high
bacterial counts on the scrotum and perineum. In a retrospective review of 131
outpatient
scrotal
procedures, Kiddoo et al. found a 9.3% overall SSI rate among patients who did
not receive
prophylactic
therapy. In contrast, Swartz et al. found a 4% SSI rate in over 100
trans-scrotal procedures with a mean follow-up of 36 months (Swartz M, Urology,
University of Washington).
Although
the precise benefit of prophylactic antimicrobials cannot be ascertained by
comparing
such
retrospective studies, these data do suggest that scrotal wounds merit
consideration as
clean-contaminated
wounds that may warrant prophylaxis.
Prophylactic
antimicrobial agents should be selected based on the most likely organisms
encountered.
Beta-lactam antibiotics, such as the cephalosporins, are the most common agents
used
for prophylaxis.
Recommendations
include cefazolin for clean abdominal procedures or cefotetan for
clean-contaminated abdominal procedures involving the gastrointestinal tract.
Clindamycin
or vancomycin regimens are recommended alternatives for patients with
documented
beta-lactam allergies. Other possible regimens include combinations of either
metronidazole
or clindamycin with gentamicin or a floroquinolone. Currently, there is no
evidence
supporting the use of prophylactic vancomycin rather than other agents, even in
hospitals with perceived high rates of bacterial resistance.
Recommendations
for specific urologic procedures are described next
Special
consideration must be given to preventing bacteremia in surgical patients with
prosthetic
joints who are at risk for joint infections or patients with certain cardiac
anomalies
who
are at risk for life-threatening endocarditis. The American Urological
Association (AUA)
and
the American Heart Association (AHA) have published specific guidelines for
antibiotic
prophylaxis
in these patient populations (as outlined previously).
Transient
bacteremia can occur after a variety of urologic procedures, especially if
patients
are
instrumented during active UTI. Identification and treatment of active
infections is strongly
recommended
prior to any elective procedure. Bacteremia is commonly associated with
urologic
procedures,
with rates of 31% for patients undergoing TURP, 24% among patients undergoing
urethral
dilations, 44% in patients having prostate needle biopsy, and 7% in patients
having
office
urodynamics. The AHA recommends endocarditis
prophylaxis for patients undergoing prostatic surgery, urethral dilations, cystoscopy,
or ureteroscopy.
Prophylaxis is
not necessary for urethral catheterization or circumcision in the absence of
clinical infections.
Perioperative ampicillin
or vancomycin with gentamicin is recommended for high-risk patients while moderate-risk
patients can be treated with single-agent ampicillin or vancomycin. High risk patients
are defined by having prosthetic heart valves, previous histories of
endocarditis, or complex congenital anomalies. Currently, the AUA recommends
assessing patients’ overall risk for artificial joint infection based on a
combination of patient-related and procedure-related factors.
