Invasive Infections Caused by Nontyphoidal Salmonella sp. in Childhood Clinical Features and Incidence Trends between 1994 and 2014

Abstract

Little is known about the clinical characteristics of invasive infections caused by nontyphoidal Salmonella sp. in childhood and the temporal changes of their incidence over a long period of time. In order to clarify these issues, we retrospectively analyzed the records of 17 such infected children admitted between August 1994 and December 2014 to our center. We divided the study period into the first (1994-1999), second (2000-2004), third (2005-2009), and fourth (2010-2014) periods. The ages of the 17 patients ranged from 2 days to 13 years. Clinical syndrome included bacteremia with enteritis (n = 13), followed by bacteremia or sepsis alone, (n = 2), osteomyelitis (n = 1), and meningitis (n = 1). The affected patient numbers in the first to fourth periods were 10, 5, 2, and 0, respectively, and the decreasing trend was significant (trend p < 0.001). This significant trend held up even after correction by the number of in-patients during each quarter period (trend p = 0.009). In the 14 cases of bacteremia with or without enteritis, excluding two neonatal cases and one case of osteomyelitis, most patients (n = 13, 93%) had WBC of <15,000/µL with a wide range of serum CRP levels (0.8-20.4mg/dL) on admission. Thus, it was very difficult to diagnose these bacteremia cases based on blood tests alone, and we needed to consider such risk factors of bacteremia as high fever, poor general condition, and younger age. O group serotypes of the isolates were as follows: O9 (n = 11), O7 (n = 5), and O4 (n = 1). Of the 15 strains evaluated, two strains were resistant to ampicillin and one each was resistant and intermediately resistant to fosfomycin. All strains were susceptible to cefotaxime, ofloxacin or levofloxacin, and trimethoprim-sulfamethoxazole. We were also presented with two rare cases : one involved sepsis due to vertical transmission and the other involved meningitis. The latter case had clinical relevance in that recurrence developed 3 weeks after treatment with susceptible antibiotics. In conclusion, this study is the first report on invasive infections caused by nontyphoidal Salmonella sp. in childhood in Japan, and provides important information on their clinical features and incidence trends over the last 20 years.