Case Report
Staphylococcus saprophyticus bacteremia after ESWL in an immunocompetent woman M. Hofmans, A. Boel, K. Van Vaerenbergh, H. De Beenhouwer Laboratory of clinical Microbiology, Onze-Lieve-Vrouw Hospital, Aalst, Belgium Staphylococcus saprophyticus is a well-known cause of uncomplicated urinary tract infections, especially in young and sexually active women. Presence in blood cultures is rare and often attributed to contamination. When bacteremia is significant, it occurs mostly in patients with hematologic malignancies and is predominantly catheter-related. However, we describe a case of significant bacteremia with S. saprophyticus associated with urinary tract infection after extracorporeal shock wave lithotripsy of an ureterolithiasis in an otherwise healthy patient. Keywords: Staphylococcus saprophyticus, Bacteremia, Urinary tract infection, ESWL
Case A 53-year-old woman, without significant medical history in our hospital, was admitted to the emergency department with colic-like pain in the left flank starting 3 days before. On admission the patient was afebrile with normal vital signs. Physical examination with costovertebral tenderness and medical imaging with ultrasound echography were suspicious for ureterolithiasis. This was confirmed by computed tomography, showing extensive ureterolithiasis, located approximately 5 cm distal of the left ureterovesical junction, with corresponding hydro-ureteronephrosis. In addition, multiple smaller lithiases in the renal pelvis and calyces of the left and right kidney were observed. Serum analysis revealed minor elevation of C-reactive protein (CRP) (14.6 mg/l [,5]) and mild leukocytosis (13 810 WBC/ml [4000–10 000]). Analysis of urine, taken on admission, showed slightly elevated white blood cell (WBC) count (50 WBC/ml [,10]), while culture only grew a small amount of normal urogenital flora (,10 000 CFU/ml). No urinary pathogens were recovered. The ureterolithiasis was successfully treated after 2 sessions of extracorporeal shock wave lithotripsy (ESWL). Antibiotic prophylaxis was not considered. After the second session of ESWL the patient started shivering. Biochemical analyses of serum revealed marked increase in inflammatory parameters, e.g. CRP (135 mg/l [,5]). Blood and urine samples for microbiological investigation were taken and Temocillin 2 grams q12 h intravenous was empirically started. Within 26 hours both aerobe (26) and anaerobe (16) Correspondence to: Dr Mattias Hofmans, Laboratory of clinical Microbiology, Onze-Lieve-Vrouw Hospital, Aalst, Belgium. Email: mattia [email protected]
ß Acta Clinica Belgica 2014 DOI 10.1179/2295333714Y.0000000111
blood cultures became positive. Direct gram staining revealed presence of gram positive cocci arranged in clusters. Next day a Staphylococcus saprophyticus was identified. Antibiotic susceptibility testing (Table 1) revealed a fully sensitive isolate, i.e. sensitive for oxacillin, ciprofloxacin, nitrofurantoin and sulfamethoxazole trimethoprim. Microscopic examination of urine, obtained simultaneously with the blood cultures, showed marked pyuria (350 WBC/ml [,10]) and hematuria (275 RBC/ml [,10]). Urine culture grew S. saprophyticus, with the same antibiotic susceptibility testing pattern as the isolate recovered from blood cultures. Based on these results, antimicrobial therapy was switched to ciprofloxacin 500 mg q12 h for 10 days. Two days after the second ESWL session the patient was discharged and a control appointment after two weeks was provided.
Discussion S. saprophyticus is a coagulase-negative Staphylococcus which has been isolated from the gastrointestinal tract of both humans and animals, as well as from meat and cheese products, vegetables and from the environment.1 It is an important urinary pathogen, second only to Escherichia coli as the most frequent causative organism in uncomplicated cystitis among young and middle-aged, sexually active, women. Especially premenopausal women are vulnerable for infection, presumably due to greater susceptibility to genitourinary inoculation from the perineal reservoir, through the ability of S. saprophyticus to adhere to uroepithelial cells by means of a surface-associated protein.2 However, in men with urinary tract infection (UTI), S. saprophyticus is
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Hofmans et al.
Staphylococcus saprophyticus bacteremia after ESWL
Table 1 Results of automated (MIC determination with Phoenix, Becton Dickinson) and manually (disk diffusion) antibiotic susceptibility testing of Staphylococcus saprophyticus isolates in blood culture (A) and in urine culture (B). Results of susceptibility testing were interpreted using clinical breakpoints derived from EUCAST v 4.0 (European committee on antimicrobial susceptibility testing) MIC (mg/l) blood culture (A)
Antimicrobial agent Oxacillin Cefoxitin Ciproxin Amoxicillin – clavulanic acid
1 4 0.25 Inferred from oxacillin 1 2 #1 .2 #0.25 #16 #1 #0.25 #0.125 #0.5 #1 #8
Vancomycin Teicoplanin Gentamicin Erythromycin clindamycin Nitrofurantoin Trimethoprim-sulfamethoxazole Rifampicin Moxifloxacin Tetracycline Tobramycin Amikacin
Disk diffusion (mm) blood culture (A)
25 24
26 24 28 28
seldom isolated and predominantly associated with indwelling urinary catheters or obstructions. Involvement of ureterolithiasis, associated to urease production, and pyelonephritis in S. saprophyticus UTI has been documented.1,2 Although coagulase-negative staphylococci constitute a frequent contaminant of blood cultures, they are among the most important pathogens involved in significant bloodstream infections and infections related to vascular and prosthetic devices. Correct identification at the subspecies level can be helpful to determine the significance and pathogenicity of the isolate. True bacteremia with S. saprophyticus is rare and difficult to distinguish from blood culture contaminants. Until today, only a few cases of significant bacteremia due to S. saprophyticus have been reported.3 Recent research, conducted in a tertiary care hospital, suggested that true bacteremia caused by S. saprophyticus is most commonly associated with tunneled-central venous catheters in patients with hematologic malignancies. Urinary tract-origin bacteremia was not described.4 According to the Clinical and Laboratory Standards Institute routine susceptibility testing of urinary S. saprophyticus isolates is not recommended since it is normally susceptible to the antimicrobial agents used for the treatment of acute uncomplicated UTIs (nitrofurantoin, sulfamethoxazole/trimethoprim, or a fluoroquinolone). However, more resistant strains have recently been documented, making antibiotic susceptibility testing recommendable, especially in invasive infections.5 Extracorporeal shock wave lithotripsy has high efficacy in treating kidney and ureteral stones acting through multiple mechanical and dynamical forces. Due to these forces, renal and vascular trauma,
2
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MIC (mg/l) urine culture (B)
Susceptibility (EUCAST)
0.5 #2 0.25
Sensitive Sensitive Sensitive Sensitive
1 2 #1 .2 #0.25 #16 #1 #0.25
Sensitive Sensitive Sensitive Resistant Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive
#0.5 #1 #8
allowing bacteria to enter the bloodstream can occur.6 The rate of bacteremia after ESWL is reportedly as high as 14% with less than 1% conversion into sepsis, with increased risk in patients with positive urine culture or with presence of urinary obstruction prior to shock wave therapy.6 The role of routine antibiotic prophylaxis in ESWL is controversial, but recent studies have demonstrated no advantage of prophylactic antibiotics when none or little risk factors are present and urine culture before lithotripsy is sterile.6 On the other hand, preoperative antibiotics are mandatory in patients with positive urine cultures prior to treatment, a history of recurrent UTI or infection-related calculus. With this case report we would like to emphasize that, although bacteremia with S. saprophyticus is rare and urinary tract-origin even more, it is not impossible. Presence of S. saprophyticus in blood culture is not always caused by contamination or catheter related infections. Urinary tract-origin bacteremia must be considered and this can be confirmed by concomitant growth of the pathogen in both blood and urine culture. It is more likely in patients undergoing urologic surgery such as ESWL. Because more resistant strains are emerging, antibiotic susceptibility testing is warranted.
References 1 Widerstrom M, Wistrom J, Sjostedt A, Monsen T. Coagulasenegative staphylococci: update on the molecular epidemiology and clinical presentation, with a focus on Staphylococcus epidermidis and Staphylococcus saprophyticus. Eur J Clin Microbiol Infect Dis. 2012;31(1):7–20. 2 Raz R, Colodner R, Kunin CM. Who are you–Staphylococcus saprophyticus? Clin Infect Dis. 2005;40(6):896–8. 3 Golledge CL. Staphylococcus saprophyticus bacteremia. J Infect Dis. 1988;157(1):215. 4 Choi SH, Woo JH, Jeong JY, Kim NJ, Kim MN, Kim YS, et al. Clinical significance of Staphylococcus saprophyticus
Hofmans et al.
identified on blood culture in a tertiary care hospital. Diagn Microbiol Infect Dis. 2006;56(3):337–9. 5 Ferreira AM, Bonesso MF, Mondelli AL, Camargo CH, Cunha ML. Oxacillin resistance and antimicrobial susceptibility profile of Staphylococcus saprophyticus and other staphylococci
Staphylococcus saprophyticus bacteremia after ESWL
isolated from patients with urinary tract infection. Chemotherapy. 2012;58(6):482–91. 6 Skolarikos A, Alivizatos G, de la Rosette J. Extracorporeal shock wave lithotripsy 25 years later: complications and their prevention. Eur Urol. 2006;50(5):981–90.
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Staphylococcus saprophyticus bacteremia after ESWL in an immunocompetent woman M. Hofmans, A. Boel, K. Van Vaerenbergh, H. De Beenhouwer Laboratory of clinical Microbiology, Onze-Lieve-Vrouw Hospital, Aalst, Belgium Staphylococcus saprophyticus is a well-known cause of uncomplicated urinary tract infections, especially in young and sexually active women. Presence in blood cultures is rare and often attributed to contamination. When bacteremia is significant, it occurs mostly in patients with hematologic malignancies and is predominantly catheter-related. However, we describe a case of significant bacteremia with S. saprophyticus associated with urinary tract infection after extracorporeal shock wave lithotripsy of an ureterolithiasis in an otherwise healthy patient. Keywords: Staphylococcus saprophyticus, Bacteremia, Urinary tract infection, ESWL
Case A 53-year-old woman, without significant medical history in our hospital, was admitted to the emergency department with colic-like pain in the left flank starting 3 days before. On admission the patient was afebrile with normal vital signs. Physical examination with costovertebral tenderness and medical imaging with ultrasound echography were suspicious for ureterolithiasis. This was confirmed by computed tomography, showing extensive ureterolithiasis, located approximately 5 cm distal of the left ureterovesical junction, with corresponding hydro-ureteronephrosis. In addition, multiple smaller lithiases in the renal pelvis and calyces of the left and right kidney were observed. Serum analysis revealed minor elevation of C-reactive protein (CRP) (14.6 mg/l [,5]) and mild leukocytosis (13 810 WBC/ml [4000–10 000]). Analysis of urine, taken on admission, showed slightly elevated white blood cell (WBC) count (50 WBC/ml [,10]), while culture only grew a small amount of normal urogenital flora (,10 000 CFU/ml). No urinary pathogens were recovered. The ureterolithiasis was successfully treated after 2 sessions of extracorporeal shock wave lithotripsy (ESWL). Antibiotic prophylaxis was not considered. After the second session of ESWL the patient started shivering. Biochemical analyses of serum revealed marked increase in inflammatory parameters, e.g. CRP (135 mg/l [,5]). Blood and urine samples for microbiological investigation were taken and Temocillin 2 grams q12 h intravenous was empirically started. Within 26 hours both aerobe (26) and anaerobe (16) Correspondence to: Dr Mattias Hofmans, Laboratory of clinical Microbiology, Onze-Lieve-Vrouw Hospital, Aalst, Belgium. Email: mattia [email protected]
ß Acta Clinica Belgica 2014 DOI 10.1179/2295333714Y.0000000111
blood cultures became positive. Direct gram staining revealed presence of gram positive cocci arranged in clusters. Next day a Staphylococcus saprophyticus was identified. Antibiotic susceptibility testing (Table 1) revealed a fully sensitive isolate, i.e. sensitive for oxacillin, ciprofloxacin, nitrofurantoin and sulfamethoxazole trimethoprim. Microscopic examination of urine, obtained simultaneously with the blood cultures, showed marked pyuria (350 WBC/ml [,10]) and hematuria (275 RBC/ml [,10]). Urine culture grew S. saprophyticus, with the same antibiotic susceptibility testing pattern as the isolate recovered from blood cultures. Based on these results, antimicrobial therapy was switched to ciprofloxacin 500 mg q12 h for 10 days. Two days after the second ESWL session the patient was discharged and a control appointment after two weeks was provided.
Discussion S. saprophyticus is a coagulase-negative Staphylococcus which has been isolated from the gastrointestinal tract of both humans and animals, as well as from meat and cheese products, vegetables and from the environment.1 It is an important urinary pathogen, second only to Escherichia coli as the most frequent causative organism in uncomplicated cystitis among young and middle-aged, sexually active, women. Especially premenopausal women are vulnerable for infection, presumably due to greater susceptibility to genitourinary inoculation from the perineal reservoir, through the ability of S. saprophyticus to adhere to uroepithelial cells by means of a surface-associated protein.2 However, in men with urinary tract infection (UTI), S. saprophyticus is
Acta Clinica Belgica
2014
VOL.
000
NO.
000
1
Hofmans et al.
Staphylococcus saprophyticus bacteremia after ESWL
Table 1 Results of automated (MIC determination with Phoenix, Becton Dickinson) and manually (disk diffusion) antibiotic susceptibility testing of Staphylococcus saprophyticus isolates in blood culture (A) and in urine culture (B). Results of susceptibility testing were interpreted using clinical breakpoints derived from EUCAST v 4.0 (European committee on antimicrobial susceptibility testing) MIC (mg/l) blood culture (A)
Antimicrobial agent Oxacillin Cefoxitin Ciproxin Amoxicillin – clavulanic acid
1 4 0.25 Inferred from oxacillin 1 2 #1 .2 #0.25 #16 #1 #0.25 #0.125 #0.5 #1 #8
Vancomycin Teicoplanin Gentamicin Erythromycin clindamycin Nitrofurantoin Trimethoprim-sulfamethoxazole Rifampicin Moxifloxacin Tetracycline Tobramycin Amikacin
Disk diffusion (mm) blood culture (A)
25 24
26 24 28 28
seldom isolated and predominantly associated with indwelling urinary catheters or obstructions. Involvement of ureterolithiasis, associated to urease production, and pyelonephritis in S. saprophyticus UTI has been documented.1,2 Although coagulase-negative staphylococci constitute a frequent contaminant of blood cultures, they are among the most important pathogens involved in significant bloodstream infections and infections related to vascular and prosthetic devices. Correct identification at the subspecies level can be helpful to determine the significance and pathogenicity of the isolate. True bacteremia with S. saprophyticus is rare and difficult to distinguish from blood culture contaminants. Until today, only a few cases of significant bacteremia due to S. saprophyticus have been reported.3 Recent research, conducted in a tertiary care hospital, suggested that true bacteremia caused by S. saprophyticus is most commonly associated with tunneled-central venous catheters in patients with hematologic malignancies. Urinary tract-origin bacteremia was not described.4 According to the Clinical and Laboratory Standards Institute routine susceptibility testing of urinary S. saprophyticus isolates is not recommended since it is normally susceptible to the antimicrobial agents used for the treatment of acute uncomplicated UTIs (nitrofurantoin, sulfamethoxazole/trimethoprim, or a fluoroquinolone). However, more resistant strains have recently been documented, making antibiotic susceptibility testing recommendable, especially in invasive infections.5 Extracorporeal shock wave lithotripsy has high efficacy in treating kidney and ureteral stones acting through multiple mechanical and dynamical forces. Due to these forces, renal and vascular trauma,
2
Acta Clinica Belgica
2014
VOL .
000
NO .
000
MIC (mg/l) urine culture (B)
Susceptibility (EUCAST)
0.5 #2 0.25
Sensitive Sensitive Sensitive Sensitive
1 2 #1 .2 #0.25 #16 #1 #0.25
Sensitive Sensitive Sensitive Resistant Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive
#0.5 #1 #8
allowing bacteria to enter the bloodstream can occur.6 The rate of bacteremia after ESWL is reportedly as high as 14% with less than 1% conversion into sepsis, with increased risk in patients with positive urine culture or with presence of urinary obstruction prior to shock wave therapy.6 The role of routine antibiotic prophylaxis in ESWL is controversial, but recent studies have demonstrated no advantage of prophylactic antibiotics when none or little risk factors are present and urine culture before lithotripsy is sterile.6 On the other hand, preoperative antibiotics are mandatory in patients with positive urine cultures prior to treatment, a history of recurrent UTI or infection-related calculus. With this case report we would like to emphasize that, although bacteremia with S. saprophyticus is rare and urinary tract-origin even more, it is not impossible. Presence of S. saprophyticus in blood culture is not always caused by contamination or catheter related infections. Urinary tract-origin bacteremia must be considered and this can be confirmed by concomitant growth of the pathogen in both blood and urine culture. It is more likely in patients undergoing urologic surgery such as ESWL. Because more resistant strains are emerging, antibiotic susceptibility testing is warranted.
References 1 Widerstrom M, Wistrom J, Sjostedt A, Monsen T. Coagulasenegative staphylococci: update on the molecular epidemiology and clinical presentation, with a focus on Staphylococcus epidermidis and Staphylococcus saprophyticus. Eur J Clin Microbiol Infect Dis. 2012;31(1):7–20. 2 Raz R, Colodner R, Kunin CM. Who are you–Staphylococcus saprophyticus? Clin Infect Dis. 2005;40(6):896–8. 3 Golledge CL. Staphylococcus saprophyticus bacteremia. J Infect Dis. 1988;157(1):215. 4 Choi SH, Woo JH, Jeong JY, Kim NJ, Kim MN, Kim YS, et al. Clinical significance of Staphylococcus saprophyticus
Hofmans et al.
identified on blood culture in a tertiary care hospital. Diagn Microbiol Infect Dis. 2006;56(3):337–9. 5 Ferreira AM, Bonesso MF, Mondelli AL, Camargo CH, Cunha ML. Oxacillin resistance and antimicrobial susceptibility profile of Staphylococcus saprophyticus and other staphylococci
Staphylococcus saprophyticus bacteremia after ESWL
isolated from patients with urinary tract infection. Chemotherapy. 2012;58(6):482–91. 6 Skolarikos A, Alivizatos G, de la Rosette J. Extracorporeal shock wave lithotripsy 25 years later: complications and their prevention. Eur Urol. 2006;50(5):981–90.
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