Extracorporeal Shock Wave Lithotripsy of Kidney Stones does not Induce Transient Bacteremia. A Prospective Study

0022-534 7 /90/1441-0015$02.00/0 THE JOURNAL OF UROLOGY Copyright© 1990 by AMERICAN UROLOGICAL ASSOCIATION, INC.

Vol. 144, July

Printed in U.S.A.

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY OF KIDNEY STONES DOES NOT INDUCE TRANSIENT BACTEREMIA. A PROSPECTIVE STUDY HENRIK WESTH, FREDDY KNUDSEN, ANNE-MARGRETE HEDENGRAN, MERETE WEISCHER, PETER MOGENSEN, JENS THORUP ANDERSEN AND THE COPENHAGEN EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY STUDY GROUP* From the Departments of Clinical Microbiology, Urology, Anesthesiology and Radiology, Bispebjerg and Hvidovre Hospitals, University of Copenhagen, Copenhagen, Denmark

ABSTRACT

During 58 extracorporeal shock wave lithotripsies 161 blood cultures were drawn to evaluate the incidence of bacteremia during the procedure. Only 3 blood cultures drawn during the procedure yielded bacteria, in all cases probably skin flora contaminants. Post-lithotripsy fever was noted in 29% of the patients, and could not be associated with transient bacteremia and was not influenced by antimicrobial prophylaxis. Patients with a positive urine culture after extracorporeal shock wave lithotripsy may have an increased risk of septicemia. (J. Ural., 144: 15-16, 1990) The management of upper urinary tract calculi has been revolutionized by the introduction of extracorporeal shock wave lithotripsy (ESWLt). To avoid infectious bacterial complications from concomitant urinary tract infection or infected calculi, patients undergoing ESWL often are given prophylactic antibiotics. Despite this therapy bacteria already present in the urine or liberated from the calculus after fragmentation by ESWL, in combination with the local tissue trauma created by the shock waves, give rise to urosepsis in approximately 0.3% of the patients. 1 • 2 Fever of greater than 38C is seen in 15 to 23% of the patients depending on patient selection. 1 • 2 This fever might be caused by transient bacteremia that often accompanies other urological procedures 3 •4 and Streptococcus faecalis endocarditis has indeed been observed after ESWL in a patient with enterococcal urinary tract infection. 5 We evaluated the incidence of transient bacteremia during ESWL and subsequent urosepsis.

from a cubital vein after iodine disinfection before ESWL, after ureteral stenting (if performed), after 1,000 shock waves, 15 minutes later and 30 minutes later if the ESWL was not yet finished. Aliquots of 10 ml. of each 20 ml. sample of blood were inoculated for aerobic and anaerobic culture into 2 blood culture bottles§ and observed 6 days for growth. All bacteria were identified to the species level. Rectal temperature was monitored continuously during ESWL with a digital thermometer DM852 with probe AR 1.11 The temperature was noted at the same time as blood was drawn and if it increased more 0.5C from the baseline temperature. The highest temperature during the 24 hours after ESWL was registered. The patients were followed for post-ESWL complications for 1 month. Prophylactic antibiotics were administered to patients with either current or prior clinical urinary tract infection, or known infection stones, or if an indwelling catheter (percutaneous nephrostomy tube, ureteral stent or bladder catheter) was placed just before ESWL. The antibiotics used were selected either according to susceptibility testing of the clinical isolates or empirically using 2 gm. ampicillin twice daily in combination with 150 mg. netilmycin twice daily given intravenously just before ESWL and continued for 24 hours. Informed consent was obtained from all patients. The study received the approval of our regional ethics committee fulfilling the criteria of Helsinki Declaration IL

PATIENTS AND METHODS

During a 5-month period 55 inpatients underwent 58 ESWL treatments with the Siemens Lithostar. ESWL was done with the patient under local infiltration analgesia, most often combined with intravenous fentanyl. All patients were given intravenous fluid infusion and 20 mg. furosemide during ESWL. Only patients from the Copenhagen Municipality entered the study to ensure appropriate followup. Mean patient age was 62 years (range 20 to 81 years). Of the patients 22 reported a prior urinary tract infection, 24 had a urinary tract infection before ESWL, 5 had infection stones, 13 entered the study with an indwelling Double-Jt ureteral stent and in 4 the stent was placed immediately before ESWL. Five patients had a nephrostomy catheter (table 1). The stones were in the caliceal system or renal pelvis in 57 treatments and in the ureter in 1. Patients were examined for bacteriuria before and 1 day after ESWL. All urine specimens were plated on 5% horse blood agar and bromthymol-blue lactose agar using inocula of 1 and 10 µl. This method allowed for quantification with a lower limit of 100 bacteria per ml. urine. Bacteriuria was defined as more than 1,000 colonies of 1 species per ml. or more than 104 colonies if there were more than 1 species. Blood cultures were drawn

RESULTS

Urine cultures before ESWL were positive in 24 patients (41 %) (table 2) but only 20 of them were given antibiotics (table 1). Day 1 of antibiotic therapy eradicated the urinary tract infection in 11 of these patients. In 4 of 22 patients with initially sterile urine and no antibiotic treatment bacteria were cultured from the urine the day after ESWL. Relevant antibiotic treatment according to the department guidelines was missed in 7 of the 34 patients not treated with antibiotics, while all 24 who received antibiotics were treated relevantly. The patients received a median of 2,600 shock waves (range 800 to 6,000). Rectal temperature was continuously monitored during 48 treatments and in 5 of these a temperature fluctuation of 0.5 to 0.9C with 4 increases and 1 decrease in temperature was measured. No temperature measured during ESWL was higher than 37.9C. The next day rectal temperature was signif-

Accepted for publication January 24, 1990. * Participants: V. Hvidt, H.-G. Iversen, R. I. Hansen, K. FeldtRasmussen, I. Walther M!llller, P. Klarskov, J. Miskowiak, 0. S. Nielsen andL. Baek. t Dornier Medical Systems, Inc., Marietta, Georgia. :j: Medical Engineering Corp., New York, New York.

§ Septi Chek, Roche Laboratories, Nutley, New Jersey.

II Ellab A/S, R!lldovre, Denmark.

15

16

WESTH AND ASSOCIATES TABLE 1. Demographic characteristics Antibiotics Group (24 treatments)

Pre-ESWL urinary tract infection Pre-ESWL urinary culture missed Infection stone Ureteral stent Nephrostomy catheter Largest stone diameter (mm.): 1-10 11-20 >20

No Antibiotics Group (34 treatments)

20

4

0 5

2 0

13

4

4

1

8

18 14 2

10 6

TABLE 2. Urinary tract infection in 58 ESWL treatments AfterESWL

Total No. Cases

Before ESWL Pos. Culture

No Growth

11* 4* 1*

11

2

19

9

0

1

24 32 2

16

30

12

58

Pos. culture No growth Not done Totals

Not Done

* One patient from each of these groups experienced urosepsis (pathogens isolated from blood and urine) 1 to 6 days after ESWL with P. aeruginosa, Strept. faecalis and Staph. epidermidis, respectively. TABLE 3. Blood culture results No Growth Before ESWL After ureteral stenting After 1,000 shock waves 15 mins. later 30 mins. later Totals

Pos. Culture

Mins. (range)

Totals

57 3

1* 0

58 3

55

2*·t

57

45 (15-270)

41 2 161

65 (30-165)

40 2 157

1* 0

4

0

* Staph. epidermidis.

t Propionibacterium acnes. icantly higher (p <0.0001 in 35 patients with both temperatures recorded) than during ESWL. Of 42 patients 12 had a temperature of more than 37.5C. A post-ESWL temperature (fever) of more than 37.5C could not be correlated to prior, concurrent or post-ESWL urinary tract infection, to the patient having an infection stone or receiving antibiotics, the size or localization of the stone, or the total number of shock waves given. There were 161 blood cultures performed in 58 treatments. One patient had only 1, 16 had 2, 36 had 3 and 5 had 4 cultures. Blood cultures after 1,000 shock waves were drawn after a median of 45 minutes and the blood culture 15 minutes later was drawn a median of 20 minutes later. Only 3 of 103 blood cultures performed during ESWL were positive (2.9%, 95% confidence limits 0.6 to 8.2%) and none of these patients had received prophylactic antibiotics (table 3). None of the bacteria isolated from blood was isolated from urine either before or after ESWL and none of these patients had clinical signs of infection. During followup 3 patients had urosepsis 1, 3 and 6 days after ESWL with Streptococcus faecalis, Pseudomonas aeruginosa and Staphylococcus epidermidis, respectively. Two of these patients should have received prophylactic antibiotics (positive urine culture before ESWL and Double-J stent placed), while 1 had no urine culture before ESWL. These procedures were not done due to protocol violation. In all 3 patients with urosepsis all pathogens were isolated from blood cultures during urosepsis (sterile blood cultures during ESWL), from urine the day of septicemia and also from the post-ESWL urine culture (table 2). DISCUSSION

Bacteremia, often with clinical signs of septicemia, after transurethral instrumentation has been reported in 10 to 32%

of the cases. 3 • 4 Treatment with antibiotics in our high risk group may have camouflaged some transient bacteremia. One pre-procedure blood culture (among 58 blood cultures) was positive. In 3 patients (table 3) blood cultures drawn during ESWL were positive (2 cases of Staph. epidermidis and 1 case of Propionibacterium acnes) but in all 3 cases the urine culture before and after ESWL was sterile and none of the patients had clinical sepsis during followup. At our hospital 2.2% of all blood culture bottles yielded bacterial contaminants, most often from the skin flora. Therefore, it is reasonable to assume that the ESWL blood isolates in this study were contaminants, since all were typical skin flora isolates known sometimes to be contaminants and all patients were well. No case of transient bacteremia with pathogens related to urinary tract infection was documented, Since the 3 isolates during ESWL were considered to be contaminants, the observed risk of transient bacteremia was O in 103 (0%, 95% confidence levels 0.0 to 3.5%), Fever after ESWL is reported in 15 to 23% and urosepsis in 0.3% of the cases. 1 •2 The cause of this fever is unknown, although the finding of a higher incidence of endotoxinemia in ESWL patients with fever (not statistically significant) in 1 study suggests that bacterial components rather than bacteria might be the cause of fever in these patients. 6 Prophylactic treatment with antibiotics often are administrated either to all patients, or only to those with either concurrent urinary tract infection or infection stones. Two studies on prophylactic antibiotics have compared placebo with antibiotics in patients without urinary tract infection 7• 8 and both have concluded that in uncomplicated ESWL antibiotics are not necessary. In our study post-ESWL fever was not influenced by prophylactic antibiotic treatment and could not be related to transient bacteremia. Our finding of urosepsis in 3 patients 1 to 6 days after ESWL indicates that selective targeting of antibiotics demands a high degree of discipline among the treating urologists. This was not demonstrated in our study, in which 20% of the patients not receiving antibiotics, including at least 2 of the 3 with post-ESWL urosepsis, were not treated despite belonging to a group who should have been treated. These 3 patients had post-ESWL bacteriuria with the bacterium that later gave rise to urosepsis. This finding might indicate that patients with a positive urine culture after ESWL are those who risk septicemia in the days after ESWL. In conclusion, our results indicate that transient bacteremia is extremely rare during ESWL, and that post-ESWL fever is not caused by transient bacteremia during ESWL and is not influenced by prophylactic antibiotic treatment. Further studies are warranted to characterize this phenomenon. Urine culture after ESWL is recommended. REFERENCES

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2.

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7. 8.

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