Pyosalpinx due to Cronobacter sakazakii in an elderly woman

Background Cronobacter sakazakii (C. sakazakii) is a bacterium known to cause severe neonatal infections in premature infants with the consumption of contaminated powdered milk formula. Adult infections are rare, and there have been no reports of pyosalpinx due to C. sakazakii to date. Case presentation We report a case of left pyosalpinx due to C. sakazakii in a sexually inactive postmenopausal woman. A 70-year-old woman presented to our hospital with left lower abdominal pain and fever. Abdominal computed tomography disclosed a cystic mass continuous with the left edge of the uterus. Urgent laparotomy revealed a ruptured left pyosalpinx with pus-like content. Left salpingo-oophorectomy, resection of the right tube, and washing of the abdominal cavity with saline were performed. Pathological examination of the left adnexa showed tubal tissue with acute inflammation and inflammatory exudate, which were compatible with pyosalpinx, and pus culture yielded C. sakazakii. Conclusions This is the first case report of pyosalpinx due to C. sakazakii. Cronobacter sakazakii infections in adult women might occur in the elderly, whose immunity has weakened. Further accumulation of cases of C. sakazakii infection is needed to clarify the etiology and behavior of C. sakazakii in adults.


Background
Cronobacter sakazakii (C. sakazakii) is a Gram-negative, rod-shaped bacterium known to cause severe neonatal meningitis and necrotizing enterocolitis in premature infants with the consumption of contaminated powdered milk formula [1,2]. Adult infections are rare [1], and there have been no reports of pyosalpinx due to C. sakazakii to date. We describe a peculiar case of left pyosalpinx due to C. sakazakii in a sexually inactive elderly woman.

Case presentation
A 70-year-old nulligravid Japanese woman presented to our hospital with a four-day history of left lower abdominal pain and fever up to 38.5 ℃. Three days previously, pyelonephritis had been suspected and an antibiotic was administered at a previous clinic, but her symptoms did not improve. Tracing back her history, she had been totally blind since 14 years old, and diagnosed with depression one year ago and received medication of 15 mg/day of Mirtazapine and 50 mg/day of Chlorpromazine hydrochloride. Her dietary habits were common, but the toothbrushing was insufficient. Therefore, several teeth had been already lost. Her husband had died and she had been sexually inactive for the last four years. Physical examination revealed evident lower abdominal tenderness and rebound tenderness. Her body temperature was 39.4 ℃ and consciousness was drowsy.
On gynecological examination, uterine cervical os was tightly closed without vaginal discharge. The uterine body was atrophic. A laboratory test showed leukocytosis with C-reactive protein of 24.36 mg/dL. Neisseria gonorrhoeae deoxyribonucleic acid (DNA) and Chlamydia trachomatis DNA in the urine were both negative. Urgent abdominal computed tomography (CT) disclosed a cystic mass of 64 × 30 mm with an equally enhanced wall (Fig. 1a). Because the cystic mass was continuous with the left edge of the uterus, a left adnexal abscess was suspected (Fig. 1b). CT also revealed ascites in the pelvic cavity and a diffusely enhanced peritoneum. Diffuse generalized peritonitis caused by rupture of the left adnexal abscess was suspected, and thus surgical intervention was planned.
Laparotomy revealed a ruptured left pyosalpinx with pus-like content (Fig. 2). The ascites had a foul smell and white moss was diffusely attached to the surface of the colon. The left ovary, uterus, and right ovary were atrophic. The right tube was slightly reddish with spreading of inflammation. Left salpingo-oophorectomy, resection of the right tube, and washing of the abdominal cavity with saline were performed. Pathological examination of the left adnexa showed tubal tissue with acute inflammation and inflammatory exudate, which were compatible with a pyosalpinx, and pus culture yielded C. sakazakii. In susceptibility testing of antibiotics, although this isolated C. sakazakii was resistant to Ampicillin, it was susceptible to other antibiotics including Cefazolin, Cefmetazole, Gentamicin, Levofloxacin, Imipenem, and Meropenem.
Because CO 2 narcosis developed in the patient, after the operation, respirator management was needed in an intensive care unit. Moreover, polymyxin B-immobilized fiber column direct hemoperfusion was performed for two days. Bacteria were not detected by blood culture performed before the operation, but antibiotics of Cefmetazole sodium for 3 days and Meropenem hydrate for 9 days were administered. The general state of the patient gradually improved and she was discharged from our hospital 21 days after the operation.

Discussion and conclusions
In 2007, organisms previously classified as Enterobacter sakazakii were reassigned to the new genus Cronobacter [2]. Cronobacter sakazakii has been isolated from clinical sources such as cerebrospinal fluid, blood and sputum, and food such as cheese, meat, and vegetables [2,3]. Most reported cases of illness caused by C. sakazakii involve infants younger than 2 months old [4]. Premature infants with underlying medical conditions are at the greatest risk. Numerous outbreaks caused by C. sakazakii have been traced to contaminated powdered infant formula [2]. Meanwhile, 17 cases of illness in adults caused by C. sakazakii have been reported in detail [1,[5][6][7][8][9][10][11][12][13].
Only 7 case reports of C. sakazakii infections involving adult women have been published in the literature (Table 1) [1,[5][6][7][8]. All of them and the current case were  of an advanced age (> 60 years), and 5 cases had underlying diseases such as malignant tumor, atrial fibrillation, cerebral stroke, cecal volvulus, and chronic renal failure. Therefore, it is suggested that C. sakazakii infections readily occur in women with weakened immunity. Isolation sites of C. sakazakii were blood, sputum, urine and bile. Most patients received surgery and/or the administration of antibiotics, but 4 died. In those cases of C. sakazakii infections who subsequently survived, cephem, quinolone or carbapenem antibiotic were administered [1,5]. The antibiotic therapy including cephem, quinolone and carbapenem might be necessary, but the administration of Ampicillin is not recommended. There have been no reports of pyosalpinx due to C. sakazakii to date; therefore, this is the first report of pyosalpinx.
Pyosalpinx and tubo-ovarian abscess are almost always complications of pelvic inflammatory disease and are sexually transmitted infections in many cases. Therefore, pyosalpinx and tubo-ovarian abscess are usually observed in young women; they are rarely found in older women. One hundred and ninety-four cases of pyosalpinx or tubo-ovarian abscess in postmenopausal woman have been reported in the literature [14][15][16][17]. Although typical organisms isolated in young women are Neisseria gonorrhea and Chlamydia trachomatis, those in reported postmenopausal women are Escherichia coli, Clostridium perfringens, Peptostreptcoccus, Group C Streptococcus, and Bacteroides fragilis [14,15]. Among physiological mechanisms causing pyosalpinx or tubo-ovarian abscess, ascending infection from the lower genital tract is the most common reason, but ascending infection might be unlikely in sexually inactive postmenopausal women. Another hypothesis of bacterial spread by hematogenous seeding has been proposed as the origin of pyosalpinx in virgin patients [18], and this hypothesis might also be applicable to postmenopausal women. Although the cause of pyosalpinx in our patient remains unclear, we speculate that hematogenous infection by C. sakazakii occurred in the hydrosalpinx that existed, and pyosalpinx developed. One of the candidate original infection sites might be the oral cavity [9].
In summary, we describe the first reported case of pyosalpinx due to C. sakazakii in a postmenopausal elderly woman. Cronobacter sakazakii infections in adult women might be caused to the elderly women whom the immunity decreased. Further accumulation of cases of C. sakazakii infection is needed to clarify the etiology and behavior of C. sakazakii in adults.

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Declarations Ethics approval and consent to participate
The study was sent to the ethical committee of Iida Municipal Hospital and need for approval was waived.

Consent to publish
Written informed consent was obtained from the patient for publication of this case report. A copy of the written consent is available for review by the Editor-in-Chief of this journal.