ABSTRACT Respiratory tract infections in poultry have become serious problems with negative consequences for poultry production. Among these diseases, mycoplasmosis and avian pneumoviruses stand out, which, despite being relevant in poultry health, have not been systematically investigated in Brazil, especially regarding the interaction between these agents or the occurrence of co-infection in broiler chickens. The present study investigated the occurrence of infection by Mycoplasma gallisepticum (MG) and subtypes A and B of avian metapneumovirus (aMPV) in broiler chickens from commercial poultry flocks kept on farms with high biosecurity standards and located in the Southeast and Midwest regions of Brazil. Polymerase chain reaction (PCR) and reverse transcription nested-PCR techniques were applied to detect and/or identify, respectively, MG and aMPV in samples of nasal and tracheal swabs collected between 2017 and 2018, from 87 batches of broiler chickens from 15 commercial production farms that showed respiratory clinical signs. Two out of 87 batches sampled (2.3%) were positive for MG, while none of them were positive for aMPV. The low or no incidence of these pathogens can be explained by the adoption of increasingly effective health control measures for these agents on farms with high biosecurity standards. In addition, there are clues that other bacterial and viral infectious agents may be involved in the etiology of respiratory problems of these broiler chickens, which showed clinical signs of respiratory diseases upon sample collection. Brazil coinfection co (MG (aMPV PCR (PCR nestedPCR nested andor identify respectively 201 2018 8 1 2.3% 23 2 3 (2.3% addition collection 20 2.3 (2.3 2. (2. (2 (

Resumo Escherichia coli são bactérias comensais e estão presentes no ambiente. Entretanto, alguns patotipos podem causar doenças em animais e humanos. E. coli APEC causa a colibacilose em aves, provocando sinais respiratórios e sistêmicos. O sorotipo enterohemorrágico O157:H7 causa infecções transmitidas por alimentos em humanos, provocando quadros de diarreia hemorrágica e síndrome hemolítico-urêmica. O objetivo do estudo foi detectar os sorotipos E. coli APEC e O157:H7 em amostras de água em diferentes pontos da produção avícola e avaliar os perfis de resistência antimicrobiana. A análise de PCR foi realizada para detectar os padrões dos genes hlyF, iutA, iroN, iss e ompTde E. coli APEC e o antígeno flagelar H7 e as toxinas Stx1 e Stx2 de E. coli O157:H7. Trinta e três amostras de água de diferentes pontos foram positivas para E. coli, entre elas, oito para APEC e nenhuma para O157:H7. Os isolados de APEC apresentaram diferentes graus de suscetibilidade aos antimicrobianos. ambiente Entretanto humanos E aves sistêmicos O157H7 OH O157 H O157:H hemolíticourêmica. hemolíticourêmica hemolítico urêmica. urêmica hemolítico-urêmica antimicrobiana hlyF iutA iroN Stx O157H7. H7. elas antimicrobianos O157H O15 O1

Abstract Escherichia coli are commensal bacteria and are present in the env/roΛ/ment. However, some pathotypes can cause disease in animals and humans. E. coli APEC causes colibacillosis in chickens, inducing respiratory and systemic symptoms. Enterohemorrhagic serotype O157:H7 causes foodborne infections in humans, with hemorrhagic diarrhea and hemolytic-uremic syndrome. The objective was to detect the E. coli APEC and O157:H7 serotypes in water samples from different points from the poultry production, and to evaluate the antimicrobial resistance profiles. PCR analysis was performed to detect the patterns of genes hlyF, iutA, iroN, iss and ompT from E. coli APEC and the H7 flagellar antigen and the Stx1 and Stx2 toxins from E. coli O157:H7. Thirty-three water samples from different points were positive for E. coli, among them, eight for APEC and none for O157:H7. APEC isolates showed different degrees of susceptibility to antimicrobials. envroΛment env roΛ ment env/roΛ/ment However humans E chickens symptoms O157H7 OH O157 O H O157:H hemolyticuremic hemolytic uremic syndrome production profiles hlyF iutA iroN Stx O157H7. H7. Thirtythree Thirty three them antimicrobials O157H O15 O1