First Report of Salmonella enterica Serotype Panama Meningitis Associated with Consumption of Contaminated Breast Milk by a Neonate

CASE REPORT

Salmonella enterica serotype Panama is a member of serogroup D1 and is isolated from many foods and animals and from water (3). It generally causes gastroenteritis in humans (12) and is one of several serotypes that tends to cause a disease in children that is more invasive than that caused by other serotypes (13). Cases complicated with bacteremia and meningitis in children have been reported previously (6, 13). The infection is often acquired through the ingestion of contaminated food. This study reports the first documented case of serotype Panama infection acquired via the consumption of contaminated breast milk.

A girl was born vaginally at term with a birth weight of 3,404 g. She was discharged after an uneventful hospitalization for 3 days. On day 13 of the postdelivery period, she exhibited several symptoms, including fever, irritable crying, poor appetite, and watery diarrhea. Her temperature was 38.9°C, blood pressure was 92/63 mm Hg, pulse rate was 152 beats/min, and respiratory rate was 50 breaths/min. Neck stiffness was also noted upon examination.

Laboratory examination revealed a white blood cell count of 19.5 × 10⁹ cells/liter with 81% neutrophils, a hemoglobin level of 15.2 g/dl, and a platelet count of 598 × 10⁹ cells/liter. The result of urinalysis was normal. Lumbar puncture was performed, and the cerebrospinal fluid (CSF) was yellow in color and slightly turbid in appearance. Analysis of CSF revealed pleocytosis with a white blood cell count of 3.030 × 10⁹ cells/liter (neutrophils versus mononuclear cells, 63 versus 37%). The red blood cell count in CSF was 0.680 × 10⁹ cells/liter, the protein concentration was 722 mg/dl, and glucose was undetectable. The concomitant plasma glucose level was 145 mg/dl. The Gram's staining of CSF was positive for gram-negative bacilli. The brain echogram revealed no abnormal findings. Salmonella group D1 was concomitantly isolated from blood and CSF samples. The isolates were susceptible to ampicillin (2 μg/ml), trimethoprim-sulfamethoxazole (<0.25/4.75 μg/ml), cefotaxime (<0.5 μg/ml), and ofloxacin (<0.03 μg/ml). The neonate was treated with intravenous cefotaxime at 200 mg/kg of body weight/day for 21 days. Repeated CSF analyses performed before discharge revealed that the CSF was clear in appearance. The white blood cell count in the CSF declined to 0.098 × 10⁹ cells/liter, with 88% lymphocytes. The protein and glucose levels were 276 mg/dl and 34 mg/dl, respectively. The Gram stain of that CSF specimen failed to discover bacteria.

The baby was fed entirely with breast milk, either directly or indirectly from freeze-thawed milk that had been stored at 4°C. A sample of frozen milk was sent to the hospital where Salmonella serogroup D1 was isolated. Repeated cultivations of breast milk were taken 2 weeks apart and collected by expressing the milk into bottles with a strict aseptic technique at the hospital. An identical serogroup of Salmonella was also cultured concomitantly. The mother was aged 34 years, pregnant five times with four births and one abortion. She was robust before and asymptomatic during the perinatal period. She did not exhibit signs of gastroenteritis or mastitis during the observation period and had no history of previous infection. The mother's cultures of the blood and stools were negative for Salmonella. The breast milk became sterile after a 7-day course of amoxicillin therapy (500 mg every 8 h). The baby and mother had no history of contact with animals. They lived in a rural area in eastern Taiwan, where they still consumed underground water. Two water samples were collected and sent for bacteriological studies, where coliform levels of 8 and 10 CFU/ml, respectively, were observed. No Salmonella was identified. No other family members developed diarrhea during the observation period.

All the Salmonella isolates were ribotyped by using an automated Riboprinter microbial characterization system (Qualicon, Wilmington, DE) according to the manufacturer's instructions. The ribotypes of the isolates from the child's blood and CSF and from the mother's breast milk were indistinguishable (Fig. 1). The organisms were identified as serotype Panama after comparing the banding patterns with the database in the Riboprinter system. The pulsed-field gel electrophoresis study showed a smear after restriction enzyme digestion (data not shown).

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FIG. 1.

Ribotyping for serotype Panama isolated from the infant and from breast milk of the mother. Lane 1, isolate from blood; lane 2, isolate from CSF; lane 3 and 4, breast milk isolates from two different periods; lane 5, Salmonella enterica serotype Infantis (ATCC 51741). M, marker lane.

The infant suffered from recurring Salmonella meningitis after discharging for 2 weeks, even though she was not fed with breast milk during this period. The stool, blood, and CSF cultures displayed the presence of Salmonella serogroup D1. Antimicrobial therapy with intravenous cefotaxime at 200 mg/kg/day was administered. Upon controlling the infection, the baby was transferred to a medical center, where a ventricular-peritoneal shunt was implanted for the obstructive hydrocephalus that was detected by a computed tomography scan.