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J Clin Microbiol. Feb 2008; 46(2): 804–806.
Published online Dec 5, 2007. doi:  10.1128/JCM.01545-07
PMCID: PMC2238107

Gardnerella vaginalis Bacteremia in a Previously Healthy Man: Case Report and Characterization of the Isolate[down-pointing small open triangle]

Abstract

Gardnerella vaginalis in women causes vaginitis or infections in other sites, such as the urinary tract, but is an infrequent cause of bacteremia. Bacteremia in men is very rare and is typically associated with immunocompromised states. Here we describe G. vaginalis bacteremia in a previously healthy man with renal calculi and urosepsis.

CASE REPORT

A 41-year-old male roofer with no prior medical problems presented with sudden onset of left flank pain. The pain was colicky in nature and not accompanied by fever, chills, urgency, or dysuria. A physical examination at the time of presentation was unremarkable. A computed tomography scan of the abdomen revealed a 6.5-mm kidney stone in the midpole of the kidney and a 3-mm calculus at the left vesicoureteric junction. Obstructive uropathy and perinephric stranding were noted. Urine biochemistry revealed slight hemoglobinuria. The patient underwent ureteroscopy the following day, and as no infection was thought to be present, no antibiotics were given. The distal ureteric calculus was not seen and was assumed to have passed spontaneously. Follow-up imaging demonstrated only the larger proximal stone. The patient was discharged from the hospital, but he returned 2 days later with worse flank pain. The computed tomography scan was repeated, and it demonstrated a 4-mm stone in the proximal left ureter, with small fragments remaining in the midpole of the kidney. Additional investigations revealed a leukocyte count of 16.0 × 109 cells/liter (normal range, 4 × 109 to 11 × 109 cells/liter) with a predominance of neutrophils (absolute count, 12.6 × 109 cells/liter; normal count, 2 × 109 to 5 × 109 cells/liter). Creatinine was elevated at 148 μmol/liter (normal range, 70 to 110 μmol/liter). The patient was readmitted for a repeat ureteroscopy. Prior to this procedure, the patient was febrile, with a temperature of 39.1°C and rigors. He appeared well otherwise, and his physical examination, including blood pressure, was unremarkable. Ciprofloxacin (400 mg intravenously every 12 h) was empirically started for presumed urosepsis. The patient's complete blood count was normal, and cultures of urine and blood (two sets, with 20 ml from one site for anaerobe and aerobic cultures and 10 ml from a second site for an aerobic bottle) were taken prior to initiation of antimicrobial therapy. The quantitative urine culture revealed 6.5 × 107 CFU/liter of a ciprofloxacin-sensitive strain of Escherichia coli. On the fifth day of incubation, the aerobic blood culture from the first set was flagged positive by the automated BacT/Alert system. A subculture of the second blood culture set revealed the same organism. The hospital laboratory was unable to achieve a definitive identification of the blood culture isolate, so the isolate was sent to a reference center.

The patient underwent a repeat ureteroscopy with lithotripsy and an extraction of the proximal stone. A ureteric stent was inserted, and it was removed the following week. The patient was treated with a 10-day course of oral ciprofloxacin and had no recurrences or sequelae.

An initial Gram stain of the blood culture revealed pleomorphic, gram-negative coccobacilli. The blood culture isolate was plated on in-house-prepared 5% sheep blood agar (base agar from Oxoid Ltd., Ottawa, Ontario, Canada; sheep blood from Quad Five, Ryegate, MT) and chocolate agar (Oxoid) in 5% CO2-MacConkey agar (Oxoid) for aerobic incubation, and brucella agar with vitamin K (Oxoid) for anaerobic incubation. After 48 h of incubation, small gray colonies were observed on the chocolate agar, with poor growth of gray, nonhemolytic colonies found on the sheep blood agar. Gram staining revealed similar gram-negative coccobacilli. Catalase and rapid oxidase tests were negative, so the isolate was referred to the Canadian National Microbiology Laboratory (NML) as a suspected isolate of Francisella tularensis. Rapid molecular testing indicated that the isolate was not F. tularensis, and further testing was undertaken, with the strain being assigned NML Special Bacteriology identifier no. 060420. A repeat Gram staining suggested that the organism was gram-positive or gram-variable short rods. The colonies were pinpoint (after 2 days) to small (~1 mm) and translucent (after 4 days), with no hemolysis observed after growth on 5% sheep blood agar. The isolate did have a narrow zone of beta-hemolysis after 4 days on vaginalis agar, which contains human red blood cells (PML Microbiologicals, Mississauga, Ontario, Canada). The isolate grew well at 37°C in 5% CO2 under strictly anaerobic conditions, but no growth was observed in air at 25°C, 37°C, or 42°C. Biochemical testing using carbohydrate (CHO) tube sugars, metabolic products of fermentation, cellular fatty acid (CFA) composition analysis, and 16S rRNA gene sequencing was performed as previously described (3, 4). Acid was observed in CHO sugars containing galactose, glucose, glycogen, maltose, sucrose, and xylose. The strain produced lipase and was negative for fermentation of fructose, glycerol, lactose, mannitol, mannose, raffinose, ribose, salicin, and trehalose. Tests for the utilization or hydrolysis of citrate, esculin, and urea, nitrate reduction, the presence of indole, staining with methyl red, and gelatin and lecithinase production, as well as the Voges-Proskauer test, were all negative. An API Strep strip used as described by the manufacturer (bioMérieux, Montreal, Quebec, Canada) generated a code of 2050001, which corresponds to a 99.8% confidence value of identification of Gardnerella vaginalis, including the utilization of starch. These reactions are consistent with the identification of G. vaginalis (6). The major metabolic product was acetic acid. The CFA composition was consistent with those observed for G. vaginalis strains referred to the NML as well as for the type strain ATCC 14018, with CFAs C14:0, C16:0, 18:1ω9c, and C18:0 predominating (3, 13).

Sequence analysis of a 1,463-bp segment of the 16S rRNA genes of the organism demonstrated 99.2% identity with G. vaginalis ATCC 14018T (GenBank accession no. M58744) and clustering within GenBank's 16S sequences for G. vaginalis only.

Antimicrobial susceptibilities were determined by broth microdilution using Sensititre GPN3F panels and cation-adjusted Mueller-Hinton broth with lysed horse blood (2 to 5% [vol/vol]) by Trek Diagnostics Inc. (Nova Century Scientific Inc., Burlington, Ontario, Canada), by using the manufacturer's instructions and following CLSI guidelines for Streptococcus spp. other than S. pneumoniae (8). The MICs (in μg/ml) observed were ≤0.25 for erythromycin, ≤0.12 for quinupristin-dalfopristin, ≤1.0 for vancomycin, 0.5 for ampicillin, ≤0.5 for rifampin, ≤0.12 for clindamycin, 0.5 for daptomycin, ≤2.0 for tetracycline, 1.0 for levofloxacin, ≤0.5 for linezolid, 0.5 for penicillin, ≤2.0 for gentamicin, 1.0 for ciprofloxacin, ≤1/19 for trimethoprim-sulfamethoxazole, ≤8.0 for ceftriaxone, and ≤1.0 for gatifloxacin, consistent with previous findings (6).

Gardnerella vaginalis is typically associated with bacterial vaginosis (6). It has also been reported as a pathogen in women following delivery or pelvic surgery, potentially leading to the preterm rupture of membranes, chorioamnionitis, and postpartum fever and to bacteremia in neonates (1, 11, 14). However, in one study, 7 to 11% of men had G. vaginalis as part of their urogenital or anorectal flora, leading to the possibility of urinary tract colonization and infection (9). In the present study, the patient had a sexual partner but the status regarding colonization or infection by this agent was not known. G. vaginalis bacteremia has rarely been described for men and usually in men with identifiable risk factors, including immunosuppression, anatomical genitourinary abnormalities, and alcoholism (2, 5, 10, 12, 15). Here we present the first published case of G. vaginalis bacteremia in a previously healthy man with urolithiasis. Although the patient's urine culture grew a potential uropathogen, it was present in <108 CFU/liter and was not identified in any of the blood cultures obtained, despite the patient not receiving antimicrobials at the time of culture. Furthermore, due to the lack of on-site microbiology facilities, 15 h elapsed from the time of specimen collection to its arrival at the microbiology laboratory, and for part of that period, refrigeration for storage of the urine was not available. Therefore, the isolation of E. coli from the urine specimen may have represented the overgrowth of a contaminant. Lastly, since two sets and three bottles of blood cultures were positive for G. vaginalis, but none were positive for E. coli, it is unlikely that E. coli played a role in his urosepsis.

The treatment of G. vaginalis infections outside the female genital tract has not been studied. Previous case reports have documented successful therapy with β-lactams, tetracyclines, cephalosporins, clindamycin, chloramphenicol, and metronidazole alone or in combination (2, 5, 10, 12, 15). Cases of severe sepsis have been treated with combination therapy (5, 12, 15). In our case, the removal of the stone and a short course of ciprofloxacin therapy were curative.

Virulence factors of G. vaginalis are not well characterized. The bacterium produces a hemolysin and a sialidase which play a role in the evasion of mucosal immunity and result in local tissue damage (7). Teichoic acid in the cell wall may produce a systemic inflammatory response after invasion, but the factors that allow the organism to cause systemic infection are not known. However, a recent report of G. vaginalis bacteremia with multifocal abscess formation in an alcoholic patient who was otherwise immunocompetent suggests that the organism has some capacity to evade the immune response (5).

In conclusion, we report the first case of urolithiasis complicated by G. vaginalis bacteremia in an otherwise well male patient. The patient was successfully treated with stone extraction and a short course of ciprofloxacin without adverse sequelae. This case illustrates that G. vaginalis may be an occasional cause of significant systemic disease in both men and women and that the original smear, being read as a gram-negative coccobacillus, caused some delay in the diagnosis and correct identification of the pathogen.

Nucleotide sequence accession number.

A nearly full 16S sequence for the isolate studied here has been deposited under GenBank accession no. EF194095.

Footnotes

[down-pointing small open triangle]Published ahead of print on 5 December 2007.

REFERENCES

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