[Epidemiology of non-typhoid salmonellosis in a hospital in Pontevedra (1994-1997)]

Abstract

Background: Since data on non-typhoidal salmonellosis in our health care area are scarce, we undertook an epidemiological study covering a four year period (1994-1997).

Methods: Retrospective descriptive study carried out through review of the medical and clinical microbiologic records at Hospital Provincial de Pontevedra. Culture, isolation, identification, antibiotic susceptibility and serotypification were done according to usual Clinical Microbiology protocols.

Results: Along the period under study 459 cases of non-typhoidal salmonellosis were diagnosed. The relative incidence was higher among pediatric than adult patients. Between 1994-1996 top incidence was detected in August, while in 1997 another maximum was found in April, closely related to climatic variations. The most frequent serogroup was D, with an increase in serogroup B since 1996. We found 16 different serotypes, being the more frequent in decreasing order Enteritidis (87.2%), Typhimurium (3.6%) and Hadar (2.3%). This distribution shows differences with regard to other national series covering a similar period of time. The more frequently detected antibiotic resistance was to ampicillin (39.0% strains), ampicillin-sulbactam (17.6%) and nalidixic acid (5.9%). Neither 3rd-generation cephalosporines nor fluoroquinolones resistance was detected. Serotype Typhimurium was the most resistant. We found association between certain resistance patterns and serotypes Hadar, Paratyphi B and Typhimurium. Most diagnosed cases corresponded to acute gastroenteritis (95.6%). Patients under 3 and over 69 suffered more frequently from extraintestinal salmonellosis.

Conclusions: The high incidence of alimentary toxinfection due to Salmonella spp. in our area should warrant strict epidemiological surveillance programmes to detect sources of infection, evaluate sanitary control measures and use of antibiotics.