Ana Terezinha Tavechio

Salmonella Serotypes Isolated from Nonhuman Sources in São Paulo, Brazil, from 1996 through 2000

A total of 4,581 Salmonella strains isolated from nonhuman sources, including foodstuffs associated with foodborne Salmonella outbreaks, from January 1996 through December 2000 were serotyped at the Enteropathogens Laboratory, Instituto Adolfo Lutz, São Paulo, Brazil. Among the 123 different serotypes identified, Salmonella enterica subsp. enterica serotype Enteritidis (Salmonella Enteritidis) was the most prevalent (32.7%), ranking first for almost every kind of source. The next most common serotypes were Salmonella Senftenberg (10.3%), Salmonella Hadar (6.8%), Salmonella Agona (5.1%), and Salmonella Typhimurium (2.4%). Rough strains belonging to the subspecies S. enterica subsp. enterica (4.8%), S. enterica subsp. arizonae (<1%), S. enterica subsp. diarizonae (<1%), and S. enterica subsp. houtenae (<1%) were also detected. Foodstuffs (including poultry meat for consumption) contained 38.1% of the studied Salmonella strains, poultry flocks (from several farms under salmonellosis control by the owners) contained 21.7%, the environment contained 10.6%, sewage contained 9.4%, water contained 6.6%, animal feed contained 4.4%, chill water from poultry-processing operations contained 2.2%, and other sources contained 7.0%. Foodstuffs extensively contaminated with Salmonella strains were poultry meat (40%), cow meat (11%), desserts (8%), mayonnaise (6%), sausage (5%), and unpasteurized shell eggs (4%), and there were several other food sources (26%). Homemade mayonnaise was the most common vehicle for Salmonella foodborne outbreaks, and Salmonella Enteritidis was the serotype most isolated (95%) from that source. According to these data and previously published data concerning Salmonella strains isolated in São Paulo State, almost the same serotypes have predominated among nonhuman sources for the last decade.

Changing patterns of Salmonella serovars: increase of Salmonella Enteritidis in São Paulo, Brazil

Serovars of a total of 5,490 Salmonella strains isolated during the period of 1991-95, from human infections (2,254 strains) and from non-human materials (3,236 strains) were evaluated. In the studied period, 81 different serovars were determined among human isolates. Salmonella Enteritidis corresponded to 1.2% in 1991, 2% in 1992, 10.1% in 1993, 43.3% in 1994, and 64.9% in 1995 of all isolates. A significant rise on the isolation of this serovar was seen since 1993 linked to food poisoning outbreaks. It is reported also an increase on the isolation of S. Enteritidis from blood cultures, associated mainly with patients with immunodeficiency syndrome. S. Enteritidis was prevalent among one hundred and thirty different serovars isolated from non-human sources. Increasing number of isolation of this serovar was seen from shell eggs, breeding flocks and from environmental samples. It is also reported a contamination of commercial feed stuffs by S. Enteritidis which represents a major concern for Brazilian poultry industry.

Salmonella em carcaças de frango congeladas

Hundred and fifty frozen broiler carcasses of four commercial brands, purchased at retail stores for Salmonella research, were examined: 43 of the carcasses referred to each of the brands A, B, D and 21 of brand C. Thirty-two percent of the samples were found positive; 11 serotypes were identified as S. Agona, S. Anatum, S. Enteritidis, S. Hadar, S. Havana, S. Mbandaka, S. Montevideo, S. Ouakam, S. Poona, S. Schwarzengrund and S.I4, 5, 12:-. Antibiogram testing of the isolated strains showed 100% resistance to ampicilin, 75.0% to cefhalotin, 52.1% to cephoxitin, 22.9% to tobramicin, 6.2% to polimixin B and to tetracyclines, 4.2% to gentamicin, and 2.1% to netilmicin, to aztreonam and to amicacin. All strains showed total sensibility to chloramphenicol and to sulfazotrim.

Salmonella serovars isolated from humans in São Paulo State, Brazil, 1996-2003.

Salmonellosis remains an important cause of diarrheal illness in humans in São Paulo State, Brazil. In this study were identified 3554 Salmonella isolates from human infections, during the period 1996-2003. Among 68 different serovars determined, S. Enteritidis was the most frequent one in gastrointestinal and extra-intestinal infections accounting for 67.4% of all isolates. S. Typhimurium and S. enterica subsp. enterica (4,5,12:i:-) were most frequently isolated from children aged < 1-4 year-old, in contrast, people with S. Enteritidis infections were most likely to be 20-50 year-old. In our geographic area the continued laboratorial surveillance of salmonellosis, including serotyping, has showed the trends in Salmonella serovars causing infections in humans throughout the time.

Phenotypic and molecular characterization of Salmonella Enteritidis strains isolated in São Paulo, Brazil

In São Paulo State, Brazil, the epidemic increase in isolation of Salmonella Enteritidis has been observed since 1994. A total of 105 S. Enteritidis strains (72 from human and 33 from non-human sources) isolated during the period 1975-1995, previously characterized by phage typing, was analyzed by antimicrobial susceptibility, plasmid profile, and ribotyping. Over 70% of the strains were susceptible to all antimicrobial agents tested, however, multiple resistance to antimicrobials was observed among the studied strains, mainly those from hospitalized patients. Phage type 8 (PT-8) was predominant among the strains isolated during the period of 1975-1992, but in the following years, PT-4 was the most frequent phage type identified. Seven different plasmid profiles were detected and 96% of the isolates harbored a plasmid of approximately 36 MDa. Ribotyping discriminated fourteen ribotypes (R1 to R14) among the strains examined. By analysis of dendrogram the strains were included in three groups with similarity level of 60%. The obtained results indicate that, a single ribotype (R11), determined for PT-4 strains isolated from 1993, characterizes the epidemic clone of S. Enteritidis in our region.

Multiplex PCR identification of the atypical and monophasic Salmonella enterica subsp. enterica serotype 1,4,[5],12:i:- in São Paulo State, Brazil: frequency and antibiotic resistance patterns

Salmonella spp. are the etiologic agents of salmonellosis, a worldwide spread zoonoses causing foodborne outbreaks and clinical diseases. By serological identification, Salmonella enterica subsp. enterica serotype 1,4,[5],12:i:- accounted for 8.8% of human and 1.6% of nonhuman Salmonella strains isolated in São Paulo State, during 1991-2000. A total of 28.6% of them amplified a fragment corresponding to H:1,2 (flagellar phase two) through PCR analysis and were further assigned as S. Typhimurium. Antimicrobial resistance was detected in 36.3% of the 369 PCR-negative strains tested, including the multiresistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin.

Surto alimentar por Salmonella Enteritidis no Noroeste do Estado de São Paulo, Brasil

A foodborne outbreak which affected 211 persons occurred, in a School, in 1993. The epidemiological data obtained by interviewing the affected and non affected persons sampled showed as predominant symptoms: diarrhoea, fever (77.7%), abdominal cramps (67.7%), vomiting (65.8%), hot-and-cold sensations (54.5%) and headache (44.5%). The median incubation period was of 17 hours, the limits being 3 and 29 hours. The disease period was of from 3 to 4 days. The food concerned was a kind of pate, a mayonnaise mixture prepared with fresh eggs with boiled potatoes that was consumed with bread. The biological material analysis - 3 coprocultures, and leftovers of the food revealed the presence of one and the same organism: Salmonella Enteritidis. In the food, the numbers of this bacterium per gram were sufficient to account for the manifestation of the disease (104 and 105/g). The antibiogram of all the isolates showed the same sensibility pattern. The preparation related to this outbreak suggests the endogenous contamination of the eggs; the cross contamination - the outbreak affected three school periods, as the food was prepared separately for each school period; and the conditions under which the food was kept during the time from preparation to consumption. The observation of the 3 food handlers, by successive coprocultures, for one week, indicates that they were not asymptomatic carriers nor were they affected as a result of this outbreak by the causal bacteria.Em 1993 ocorreu um surto alimentar em escola, com 211 afetados. Os dados epidemiologicos levantados por entrevista de amostragem de afetados e nao afetados mostraram que os sintomas predominantes foram diarreia, febre (77,7%), dor abdominal (67,7%), vomito (65,8%), calafrios (54,5%) e cefaleia (44,5%). A mediana de incubacao foi de 17 horas, com limites entre 3 e 29 horas. A duracao da doenca foi de 3 a 4 dias. O alimento consumido foi um tipo de pate, mistura de molho de maionese preparada com ovos crus com batata cozida, passado em pao. A analise de material biologico (3 coproculturas) e de restos de alimentos revelou a presenca do mesmo microrganismo, a Salmonella Enteritidis. No caso dos alimentos, o numero encontrado desta bacteria por gramo de produto era compativel com a quantidade de celulas necessaria para desencadear a doenca (104e 105/g). O antibiograma de todas as cepas isoladas revelou o mesmo padrao de sensibilidade. As falhas no preparo do alimento relacionadas com o levantamento indicam a possibilidade de contaminacao endogena dos ovos; contaminacao cruzada - o surto afetou tres periodos escolares, sendo que para cada um o alimento foi preparado em separado - e as condicoes de manutencao do alimento apos preparo e ate o consumo. A observacao por uma semana seguida das 3 merendeiras envolvidas, atraves de coprocultura, nao indicaram que as mesmas fossem portadoras assintomaticas desta bacteria ou que tivessem sido envolvidas no surto em questao.A foodborne outbreak which affected 211 persons occurred, in a School, in 1993. The epidemiological data obtained by interviewing the affected and non affected persons sampled showed as predominant symptoms: diarrhoea, fever (77.7%), abdominal cramps (67.7%), vomiting (65.8%), hot-and-cold sensations (54.5%) and headache (44.5%). The median incubation period was of 17 hours, the limits being 3 and 29 hours. The disease period was of from 3 to 4 days. The food concerned was a kind of paté, a mayonnaise mixture prepared with fresh eggs with boiled potatoes that was consumed with bread. The biological material analysis-3 coprocultures, and leftovers of the food revealed the presence of one and the same organism: Salmonella Enteritidis. In the food, the numbers of this bacterium per gram were sufficient to account for the manifestation of the disease (10(4) and 10(5)g). The antibiogram of all th isolates showed the same sensibility pattern. The preparation related to this outbreak suggests the endogenous contamination of the eggs; the cross contamination-the outbreak affected three school periods, as the food was prepared separately for each school period; and the conditions under which the food was kept during the time from preparation to consumption. The observation of the 3 food handlers, by successive coprocultures, for one week, indicates that they were not asymptomatic carriers nor were they affected as a result of this outbreak by the causal bacteria.

Progression of Salmonella Enteritidis phage type 4 strains in São Paulo State, Brazil

A total of 574 S. Enteritidis strains (383 from human sources and 191 from non-human sources) isolated between 1975-95, in São Paulo State, Brazil, were phagetyped. Among the strains isolated during the period of 1975-92, 80.9% of them belonged to phage type 8 (PT-8), but in 1993 strains of PT-4 accounted for 65.2% of all the S. Enteritidis isolates. In the following years, PT-4 strains accounted for 99.7% and 98.4% of phagetyped S. Enteritidis strains. The results obtained suggested that the current epidemic of S. Enteritidis in São Paulo State is clearly associated with the progression of PT-4 strains.

CTX-M-2-Producing salmonella typhimurium isolated from pediatric patients and poultry in Brazil

Ten Salmonella enterica serovar Typhimurium isolates producing CTX-M-2 extended-spectrum beta-lactamase were identified from clinical and poultry sources in two distant cities in Brazil between 2003 and 2004. They included two isolates from pediatric patients and eight isolates from poultry or its environment. All isolates exhibited coresistance to non-beta-lactam antimicrobials including tetracycline and trimethoprim/sulfamethoxazole. The CTX-M-2 gene was located on transferable plasmids with sizes between 90 and 170 kb that also carried other resistance determinants in some isolates. By pulsed-field gel electrophoresis, the genetic similarity of the isolates including clinical and poultry ones ranged from 89% to 100%.

Antimicrobial susceptibility, phage types, and pulsetypes of Salmonella Typhimurium, in São Paulo, Brazil

A total of 283 Salmonella Typhimurium strains isolated from cases of human infections and non human sources, were examined for antimicrobial susceptibility and the incidence of resistance was 38% and multiple resistance (to three or more antimicrobials) was 15%. All 43 multidrug-resistant strains (MDR) and 13 susceptible ones were characterized by phage typing and pulsed- field gel electrophoresis (PFGE). The strains encompassed 14 definitive phage types (DT), three were untypable (UT), and 18 atypicals or reaction does not conform (RDNC), which belonged to 21 PFGE patterns, A1-A21. The predominant phage types were DT49, DT193, and RDNC and two strains belonging to DT 104 and 104b were also identified. The most common PFGE patterns were A1 and A8. Analysis by PFGE and phage typing demonstrated that the most of the MDR were multiclonal and association among multiresistance, phage typing, and PFGE patterns was not so significant.