Infection after transrectal ultrasound-guided prostate biopsy

Transrectal ultrasound-guided prostate biopsy (TRUS-Bx) is one of the most commonly performed urologic procedures in the United States and Europe, with approximately one million biopsies performed annually on each continent. TRUS-Bx is a relatively safe procedure and the chances of severe complications are low, but the incidence of infectious complications has recently been rising, along with the potential for more severe complications such as sepsis [1, 2]. Escherichia coli is the most common pathogen found in infections after TRUS-Bx [3, 4, 5, 6]. Randomized controlled trials have shown that antibiotic prophylaxis is effective in preventing infectious complications following TRUS-Bx [7]. Fluoroquinolone is the most commonly used antibiotic agent for prophylaxis [7, 8]. However, worldwide antibiotic resistance is rising [9, 10, 11], and as such, infectious complications after TRUS-Bx by fluoroquinolone-resistant E. coli are rising as well [9, 12, 13, 14].

The incidence of infectious complications after TRUS-Bx is reported to range from 0.1% to 7%; the incidence of infections requiring admission is from 0.6% to 4.1% [15]. In Korea, the reported incidence of infectious complications after TRUS-Bx is from 0.65% to 3.1% [16, 17, 18]. In another Asia-Europe multicenter study that included Korea, the reported incidence of febrile urinary tract infection (UTI) was 3.5% and the incidence of infections requiring admission was 3.1% [19]. In Japan, the reported incidence of febrile UTI was from 0.5% to 0.76% [20, 21], and in Taiwan, the incidence was 5.4% before fluoroquinolone prophylaxis and 0.9% after fluoroquinolone prophylaxis [22]. A Turkish study reported an incidence of infections requiring admission of 2% [23].

The incidence of infectious complications after TRUS-Bx has been rising in recent years. In a study that analyzed complications after prostate biopsy from SEER (Surveillance, Epidemiology and End Results)-Medicare data from 1991 to 2007, infectious complications after prostate biopsy increased in recent years [1]. In a Canadian report, the incidence of infectious complications that required admission was 1.0% in 1996 but increased to 4.1% in 2005, 72% of which was sepsis [2]. Another recent Canadian report also stated that the incidence of infectious complications was 0.52% from 2002 to 2009 but increased to 2.15% from 2010 to 2011 [24]. The main reason for this increase in infectious complications is the rise in fluoroquinolone resistance [9].

In one Korean study, acute bacterial prostatitis after TRUS-Bx occurred in 1.36% of patients and the prevalence of fluoroquinolone-resistant strains was 23.8% [25]. In a Japanese study, acute bacterial prostatitis developed in 1.3% of patients and all urine and blood cultures yielded levofloxacin-resistant E. coli [26]. In another Japanese study, the rate of genitourinary tract infection was 0.76% and E. coli was the most frequently isolated strain, of which 77.8% showed levofloxacin resistance [21]. In a North American cohort, 2.77% of cases developed infection after biopsy, of which 55% had fluoroquinolone-resistant infection [6]. In a French prospective study, 0.67% of cases had acute bacterial prostatitis, of which 95% showed fluoroquinolone resistance [27]. In an Australian study that analyzed E. coli bacteremia after TRUS-Bx, 62% were fluoroquinolone-resistant [28]. Overall, the reported prevalence of fluoroquinolone resistance in infectious complications after TRUS-Bx ranges from 24% to 100%, and considering the recent trend in increasing antibiotic resistance, fluoroquinolone resistance is expected to rise rapidly. Along with the problem of fluoroquinolone resistance, one should also be wary of the emergence of extended-spectrum beta-lactamase (ESBL)-producing bacteria. One study reported an incidence of ESBL-producing bacteria of 43% in acute prostatitis after TRUS-Bx [29].

Investigators from the United States [12] and Japan [30] monitored the rates of fluoroquinolone-resistant E. coli before TRUS-Bx, with results of 23% and 13%, respectively. The purpose of monitoring for fluoroquinolone-resistant E. coli before TRUS-Bx would be to select appropriate prophylactic antibiotics that can specifically target antibiotic-resistant organisms. Targeted prophylaxis may not only prevent infectious complications and sepsis after TRUS-Bx but also suppress the rise of antibiotic-resistant bacteria. In a study conducted to evaluate targeted antibiotic prophylaxis in men undergoing TRUS-Bx in the United States, there were no infectious complications in the 112 men who received targeted antibiotic prophylaxis, whereas there were 9 cases (including 1 of sepsis) among the 345 men on empirical therapy [31]. That study also evaluated the cost-effectiveness of targeted prophylaxis and showed that targeted prophylaxis yielded a cost savings of US $4,499 per TRUS-Bx infectious complication averted. However, debate remains as to whether rectal swab cultures should be routinely performed before TRUS-Bx. In a Canadian study, despite a significant correlation between patients who developed infections and the detection of ciprofloxacinresistant organisms, only 9.0% of the total group with ciprofloxacin resistance developed an infectious complication [32]. Future studies will need to evaluate the cost effectiveness and clinical utility of a prebiopsy rectal culture in targeted antibiotic prophylaxis [32].

Fluoroquinolones have been the most common choice for prophylactic antibiotics preceding TRUS-Bx. Infectious complications after TRUS-Bx are increasing, and this appears to be due to an increasing prevalence of floroquinolone-resistant strains in the rectal flora. Therefore, identifying the risk for fecal carriage of floroquinolone-resistant strains by history taking should be the initial step in the TRUS-Bx procedure. If a risk of fluoroquinolone resistance is present, targeted antimicrobial prophylaxis using rectal swab cultures or alternative antibiotics may be recommended for prophylaxis. In patients with infectious complications after TRUS-Bx, it is essential to administer appropriate antibiotics immediately.