SUMMARY
Raoultella ornithinolytica is one of the three species of Raoultella. The present case report describes a two-year-old child who had complaints of discomfort and fever, and Raoultella ornithinolytica in his urinary culture. Grade-2 hydronephrosis and a 7.5-mm urinary stone were detected in the patient’s left ureter. The stone was expelled upon consultation with pediatric urology department. The patient was treated according to culture antibiotic sensitivity report and continued to be followed-up.
Key words: Raoultella ornithinolytica, Urinary stone, Childhood, Urinary tract infection
Introduction
Urinary tract infection is any infection of a part of urinary tract (1). Raoultella spp. are microorganisms which rarely cause infection in people, belong to Enterobacteriaceae family, are facultative gram (-), catalase (+), oxidase (-), capsule-free, immobile, and can produce histamine. This bacterium was first defined by Kosako et al. in 1989 (2). It is found in aquatic environments, fish and insects. Raoultella ornithinolytica (R. ornithinolytica) is a histamine-producing bacterium that causes fish poisoning (3, 4).
In this case report, a case in a child with complaints of discomfort and fever is described. The child was diagnosed with R. ornithinolytica in his urinary culture and left ureter stone in his urinary system, without any underlying predisposing reason, unlike cases in the literature. To our knowledge, this is the second childhood case of human infection with R. ornithinolytica reported in the literature.
Case Report
A 2-year-old male patient was admitted to pediatric polyclinic due to fever. History of the patient revealed that he also had fever one week before and had been treated for upper respiratory tract infection at another institution but developed fever again on the 7th day of treatment. According to the patient’s history, upon delivery by cesarean section, his birth weight was 3450 g, length 50 cm and head circumference 35 cm. He was hospitalized at the newborn intensive care unit for 7 days due to hyperbilirubinemia and neonatal sepsis on the postnatal day 4, and there was no reproduction in the blood and urinary cultures. Afterwards, he did not have frequent admissions to hospital or hospitalization. There was no known disease in his family history. On physical examination, the values were as follows: body weight 12.5 kg (50th percentile) and height 87 cm (25th-50th percentile). Physical examination was normal and his body temperature was 37.2 oC. Complete blood count showed the following values: WBC 19.2x103/µL (52.6% neutrophil, 37% lymphocyte); Hb10.7 g/dL; HTC 31.9%; MCV 74 fL; RDW 16.8; Plt 332000x103/µL; C-reactive protein 3.04 mg/dL (0-0.5 mg/dL); biochemical parameters were normal. Urine dipstick (with urine bag) was positive for leukocytes and negative for blood/hemoglobin, nitrite. There were 12-14 leukocytes and abundant amorphous crystals in every field in urinary sediment. Urinary system ultrasound revealed a 7.5-mm stone and grade 2 hydronephrosis distally in the left ureter (Fig. 1). In his urinary culture, ≥105 CFU/mL R. ornithinolytica was detected. According to the antibiotic sensitivity report, it was sensitive to trimethoprim/sulfamethoxazole, amoxicillin/clavulanic acid, gentamicin, cefuroxime axetil but resistant to ampicillin. For confirmation, urine sample and culture were obtained with a catheter under sterile conditions. Moreover, necessary tests for stone etiology were ordered and oral cefuroxime axetil was started in the patient. In urinary culture taken with the catheter, 105 CFU/mL R. ornithinolytica reproduced and the antibiotic sensitivity report was the same as the former one. The urine was cultivated on EMB and blood agar. The colonies proliferated in both agars selected for gram staining and gram-negative bacilli were isolated. Bacterial identification was carried out using the VITEK-2 compact system. Immunoglobulins of the patient were in the normal range for his age. In the tests performed for stone etiology, calcium/creatinine, oxalate, citrate, magnesium and uric acid values were in the proper range in the spot urine according to his age. Due to grade 2 hydronephrosis, his endoscopic stone was removed by a pediatric urologist and double J catheter was introduced. Follow-up of the patient having remission of hydronephrosis has been continued at the nephrology and pediatric urology clinics.
Fig. 1.
Urinary stone ultrasound image.
Discussion
In the literature, Raoultella spp. is reported only in sporadic cases as the pathogens responsible for human infections across the world. To our knowledge, there are four childhood cases including newborn cases. Notably, while primary or secondary immunodeficiency and serious diseases were detected in these children, there was no such etiologic cause in our case. The first human infection caused by R. ornithinolytica was reported in 2009 (3). Moreover, the first case in whose blood or urinary samples R. ornithinolytica reproduction was reported in the pediatric group was a preterm infant presenting with septic shock and purpura fulminans and dying at 19 days of age (5). The second case of R. ornithinolytica presented with bacteremia, asplenia, congenital cardiac defects and visceral heterotaxy (6). The third one was a 21-day-old male patient who was treated due to urinary tract infection (7). The fourth patient was aged 8 years and had R. ornithinolytica sepsis due to central venous catheter while in intensive care unit for retinoblastoma (8). Characteristics of these cases are shown in Table 1.
Table 1. Characteristics of Raoultella ornithinolytica cases reported in childhood.
| Reference | Age/Sex | Isolated specimen | Clinical manifestation | Treatment | Outcome |
|---|---|---|---|---|---|
| Sandal and Ozen, 2014 (5) | Preterm 19 days / female | Blood | Septic shock and purpura fulminans | Meropenem + vancomycin | Died |
| Mau and Ross, 2010 (6) | 3 days / male | Blood | Bacteremia | Amikacin + meropenem | Recovered |
| Akyuz Ozkan et al., 2014 (7) | 21 days / male | Urine | Urinary tract infection | Amikacin | Recovered |
| Sękowska et al., 2015 (8) | 8 years / male | Blood | Catheter-related blood stream infection, septicemia | Piperacillin + tazobactam + amikacin | Recovered |
A characteristic common to these cases is that all of them were newborn infants except for the last case. Immunosuppression was available in the last case as in the newborn infants. Our case, however, was a two-year-old child who had normal growth and development, did not have immunodeficiency, and was the first child in whose urinary culture this bacterium was isolated.
In addition, Chondros et al. (9) isolated this agent in complicated urinary tract infection due to urinary stone in an adult case, as in our case. R. ornithinolytica was isolated from blood culture specimens in 16 adult cases. The majority of these patients had an underlying malignant condition of advanced stage (15 patients, 94%) (10). Likewise, in another study, R. ornithinolytica was isolated in nine adult patients diagnosed with cystitis (11). R. ornithinolytica is usually resistant to ampicillin. In the present case, ampicillin resistance was also recorded. We administered cefuroxime therapy to our patient for 10 days according to the antibiotic sensitivity report, and follow-up urine culture was negative.
In conclusion, this is the second childhood case except for the newborns reported in the literature, and urinary stone was found as the underlying etiology. Successful treatment with proper antibiotic was performed in this child. Although rarely seen in children, R. ornithinolytica may be a life-threatening infection, especially in newborns.
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