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Caracterização microbiológica e molecular das estirpes de Salmonella spp. isoladas em amostras clínicas, águas residuais e alimentos na região de Luanda e dos seus perfis de resistência aos antimicrobianos - o seu impacto na saúde pública.
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As infeções por Salmonella spp. são comuns em África, estando entre as principais causas de morbilidade e mortalidade em humanos, com impacto para a saúde pública. Não existe registo científico da sua situação em Angola apesar dos inúmeros registos informais e suspeitas clínicas destas infeções associadas a doença entérica e perfurações intestinais. Este trabalho consistiu no isolamento e caracterização dos diferentes serovares de Salmonella que circulam em Luanda, Angola, relativamente aos seus padrões de resistência aos antimicrobianos e relação epidemiológica, em particular entre isolados clínicos, ambientais e alimentares, e compreender o seu impacto na saúde pública angolana. Das 290 amostras colhidas entre Agosto de 2013 e Novembro de 2015, foram obtidos 65 isolados de Salmonella spp. identificados por provas bioquímicas (galeria API). A confirmação do género Salmonella foi feita por amplificação do gene invA. Todos os isolados foram serotipados com base no esquema de Kauffmann-White-Le Minor e tipados molecularmente por XbaI-PFGE. Isolados representativos foram ainda analisados por MLST. O perfil de susceptibilidade aos antimicrobianos foi obtido por determinação de concentrações mínimas inibitórias, e os seus determinantes de resistência pesquisados por PCR.
Dos 65 isolados de Salmonella spp., 10 corresponderam a S. enterica serovar Typhi, colhidos em pacientes com suspeita clínica de febre tifóide ou doença entérica. Nelas foi detectada resistência ao trimetoprim-sulfametoxazole (n=6), aos beta-lactâmicos (n=5), ao cloranfenicol (n = 1) e ainda susceptibilidade reduzida à ciprofloxacina (n = 2). A tipagem molecular por XbaI-PFGE revelou oito pulsotipos, associados por MLST a três sequências-tipo: ST1, ST2 e ST8, sendo ST2 predominante.
Os restantes 55 isolados de Salmonella spp. (de origem clínica (32, 58%); ambiental (13, 22.4%); alimentar (10, 18.2%)) corresponderam ao serovar Enteritidis (17, 30.9%), ao serovar Typhimurium (12, 21.8%), e em particular à sua importante e altamente virulenta variante monofásica 4[5],12:i-:- (21, 38.1%). O padrão de resistência mais frequente foi a resistência à colistina (5, 9.0%), seguido-se de resistência à ampicilina, ampicilina/sulbactam, piperalicina, cloranfenicol e trimetoprim-sulfametoxazole (2, 3.6 %). A tipagem molecular discriminou 4 pulsotipos (A a D), sendo o pulsotipo B o mais frequente (n=28, 20 de 4[5],12:i:-, 4 Typhimurium e 4 de serovar desconhecido), o qual foi associado à linhagem clonal ST313. O segundo pulsotipo mais frequente, A, com 20 isolados, maioritariamente Enteritidis e associados à linhagem ST11. O pulsotipo C, com 4 isolados, 3 Typhimurium e 1 de serovar desconhecido, foi relacionado a um novo ST. Por sua vez, o pulsotipo D, com três isolados Typhimurium todos associados ao ST1561. Todos os pulsotipos encontrados continham amostras de origem clínica, alimentar e ambiental, revelando as fontes de transmissão deste agente, à exceção do pulsotipo D composto apenas por isolados de origem ambiental.
Estes resultados fornecem, pela primeira vez, uma primeira caracterização microbiológica e molecular da situação epidemiológica das infeções por Salmonella spp. em Luanda, e evidenciam a necessidade de contínuo monitoramento deste agente patogénico ao nível clínico, alimentar e ambiental para que se implementem estratégias epidemiológicas para o controlo da febre tifóide e de outras salmoneloses em Angola.
Infections caused by Salmonella spp. are common in Africa and amongst the main causes of morbidity and mortality in humans, with a public health impact. There is no scientific record of their situation in Angola, despite the innumerous records of informal and clinical suspicions of these infections as cause of enteric disease and intestinal perforations. This work involved the isolation and characterization of the different Salmonella serovars circulating in Luanda, Angola, regarding their antimicrobial resistance patterns and epidemiological relationship, particularly between clinical, environmental and food isolates and their impact on public health in Angola. From 290 samples collected between August 2013 and November 2015, 65 isolates of Salmonella spp. were identified by biochemical tests (API gallery). Confirmation of the genus Salmonella was achieved by amplification of the invA gene. All isolates were serotyped based on the Kauffmann-White-Le Minor scheme and typed by XbaI-PFGE representatives isolates of the clones detected were further analyzed by MLST. The antimicrobial susceptibility profile was obtained by determining their minimum inhibitory concentrations and their resistance determinants were screened by PCR. Of the 65 isolates of Salmonella spp., 10 corresponded to S. enterica serovar Typhi, collected in patients with clinical suspicion of typhoid or enteric disease. Resistance to trimethoprim-sulfamethoxazole (n = 6), beta-lactams (n = 5), chloramphenicol (n = 1) and reduced susceptibility to ciprofloxacin (n = 2) were detected. Molecular typing by XbaI-PFGE revealed eight pulsotypes and three MLST-associated sequence-types: ST1, ST2 and ST8, being ST2 predominant. The remaining 55 isolates of Salmonella spp., (of clinical origin (32,58%); environmental (13, 22.4%); food (10, 18.18%)), corresponded to serovar Enteritidis (17, 30.9%), Typhimurium (12, 21.8%), and in particular of its important and highly virulent monophasic variant 4[5],12:i-:- (21 isolates. The most frequent resistance pattern was resistance to colistin in 5 isolates (9.0%), followed by resistance to ampicillin, ampicillin/sulbactam, piperacilin, chloramphenicol and trimethoprim-sulfamethoxazole in 2 isolates (3.6%). Molecular typing discriminated 4 pulsotypes (A to D), with pulsoytpe B being the most frequent (n = 28, 20 being serovar 4[5],12:1-:-, 4 Typhimurium and 4 serovar unknown), associated with clonal line ST313 by MLST. The second most frequent pulsotype was A, represented by 20 isolates, mainly serovar Enteritidis, associated to ST11 lineage. Pulsotype C, composed of 4 isolates, 3 Typhimurium and 1 unknown serovar, was related to a new ST. The D pulsotype, contained three Typhimurium isolates all associated with ST1561. All pulsotypes contained samples of clinical, food and environmental origin, revealing the sources of transmission of this agent, except for pulsotype D composed only by environmental isolates. These results provide, for the first time, an initial microbiological and molecular characterization of the real epidemiological situation of Salmonella spp. infections in Luanda and demonstrate the need for continuous monitoring of this pathogenic agent at the clinical, food and environmental levels to implement epidemiological strategies for the control of typhoid fever and other salmonellosis in Angola.
Infections caused by Salmonella spp. are common in Africa and amongst the main causes of morbidity and mortality in humans, with a public health impact. There is no scientific record of their situation in Angola, despite the innumerous records of informal and clinical suspicions of these infections as cause of enteric disease and intestinal perforations. This work involved the isolation and characterization of the different Salmonella serovars circulating in Luanda, Angola, regarding their antimicrobial resistance patterns and epidemiological relationship, particularly between clinical, environmental and food isolates and their impact on public health in Angola. From 290 samples collected between August 2013 and November 2015, 65 isolates of Salmonella spp. were identified by biochemical tests (API gallery). Confirmation of the genus Salmonella was achieved by amplification of the invA gene. All isolates were serotyped based on the Kauffmann-White-Le Minor scheme and typed by XbaI-PFGE representatives isolates of the clones detected were further analyzed by MLST. The antimicrobial susceptibility profile was obtained by determining their minimum inhibitory concentrations and their resistance determinants were screened by PCR. Of the 65 isolates of Salmonella spp., 10 corresponded to S. enterica serovar Typhi, collected in patients with clinical suspicion of typhoid or enteric disease. Resistance to trimethoprim-sulfamethoxazole (n = 6), beta-lactams (n = 5), chloramphenicol (n = 1) and reduced susceptibility to ciprofloxacin (n = 2) were detected. Molecular typing by XbaI-PFGE revealed eight pulsotypes and three MLST-associated sequence-types: ST1, ST2 and ST8, being ST2 predominant. The remaining 55 isolates of Salmonella spp., (of clinical origin (32,58%); environmental (13, 22.4%); food (10, 18.18%)), corresponded to serovar Enteritidis (17, 30.9%), Typhimurium (12, 21.8%), and in particular of its important and highly virulent monophasic variant 4[5],12:i-:- (21 isolates. The most frequent resistance pattern was resistance to colistin in 5 isolates (9.0%), followed by resistance to ampicillin, ampicillin/sulbactam, piperacilin, chloramphenicol and trimethoprim-sulfamethoxazole in 2 isolates (3.6%). Molecular typing discriminated 4 pulsotypes (A to D), with pulsoytpe B being the most frequent (n = 28, 20 being serovar 4[5],12:1-:-, 4 Typhimurium and 4 serovar unknown), associated with clonal line ST313 by MLST. The second most frequent pulsotype was A, represented by 20 isolates, mainly serovar Enteritidis, associated to ST11 lineage. Pulsotype C, composed of 4 isolates, 3 Typhimurium and 1 unknown serovar, was related to a new ST. The D pulsotype, contained three Typhimurium isolates all associated with ST1561. All pulsotypes contained samples of clinical, food and environmental origin, revealing the sources of transmission of this agent, except for pulsotype D composed only by environmental isolates. These results provide, for the first time, an initial microbiological and molecular characterization of the real epidemiological situation of Salmonella spp. infections in Luanda and demonstrate the need for continuous monitoring of this pathogenic agent at the clinical, food and environmental levels to implement epidemiological strategies for the control of typhoid fever and other salmonellosis in Angola.
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Microbiologia médica Ciências biomédicas Saúde pública Salmonella spp. Salmonella Typhi Antimicrobianos Luanda Angola