First Human Case of Salmonella enterica Serotype Landwasser Recovered from Breast Fluid

We report the first human case of Salmonella enterica Serotype Landwasser infection. The identification of this extremely unusual serotype was established at the Enterics Section of the Public Health Diagnostic Microbiology Laboratory of the State of Maryland Department of Health in Baltimore.

A 47-year-old woman presented with a 3-day history of right breast pain. The patient denied trauma to the area. The breast pain followed a 2-day episode of what she described as flu-like illness (stomach virus) after she ate crabmeat. She also complained of right arm and shoulder pain with stiffness. Her left breast was normal. On physical examination, her blood pressure was 134/82, her temperature was 98.1°F, and her pulse was 93. There was a palpable, tender, mobile mass measuring approximately 5 by 5 cm on the lower outer quadrant of the right breast. The area surrounding the aerola was tender, erythematous, and warm to the touch. The left breast was normal without masses, nipple discharge, or retraction. There were no other physical findings. The patient underwent an ultrasound of the right breast that revealed cystic fluid that was aspirated. A 20-gauge needle was used to aspirate a small amount of fluid with a milky appearance, which was sent for culture and sensitivity determinations. The culture of the aspirate was positive for Salmonella at the hospital laboratory, and the patient was treated with 500 mg of ciprofloxacin twice daily for 7 days. The hospital laboratory forwarded the Salmonella isolate to the Public Health Diagnostic Microbiology Laboratory at the State of Maryland Department of Health and Mental Hygiene, where the isolate was identified as S. enterica serotype Landwasser (3,10:Z:Z6). The Centers for Disease Control and Prevention have confirmed this finding. Antibiotic susceptibility testing of the isolate showed that the strain was susceptible to a wide variety of agents, including amikacin, ampicillin, aztreonam, ampicillin-sulbactam, ceftriaxone, cephalothin, ciprofloxacin, gentamicin, imipenem, tetracycline, and trimethoprim-sulfamethaxazole. The patient's symptoms resolved after aspiration of the cyst, and she had no further symptoms. Both the infection site (extraintestinal) and the fact that it is the first to be reported in humans make this case especially unique. The patient denied having pets, lizards in particular, and had no travel history. Stool culture was not done on the patient, and the source of this infection remains unknown to us.

To our knowledge, this is the first case of S. enterica serotype Landwasser infection in a human host. A literature search did not reveal any other reported cases due to this serotype. The organism was originally isolated in 1979 from a lizard and reported by Le Minor et al. (5).

Salmonella species cause a wide spectrum of infections, ranging from self-limited to life-threatening typhoid fever. Salmonella species are usually associated with gastrointestinal infections; however, extraintestinal Salmonella infections are not unusual. Numerous reports in the literature have associated Salmonella species with bloodstream infections (6, 9), burn wounds (7, 8), liver abscesses (2, 3), surgical wounds (4, 10), and joint infections (1). This report further demonstrates the importance and role of the public health microbiology laboratories in the identification, surveillance, and control of new and emerging infections.