Identification of swine influenza A virus and Stenotrophomonas maltophilia co-infection in Chinese pigs

Abstract

BackgroundInfluenza virus virulence can be exacerbated by bacterial co-infections. Swine influenza virus (SIV) infection together with some bacteria is found to enhance pathogenicity.MethodsSIV-positive samples suspected of containing bacteria were used for bacterial isolation and identification. Antimicrobial susceptibility testing was performed by disc diffusion methods. To investigate the interaction of SIV and the bacteria in vitro, guinea pigs were used as mammalian hosts to determine the effect on viral susceptibility and transmissibility. Differences in viral titers between groups were compared using Student’s t-test.ResultsDuring surveillance for SIV in China from 2006 to 2009, seven isolates (24.14%) of 29 influenza A viruses were co-isolated with Stenotrophomonas maltophilia from nasal and tracheal swab samples of pigs. Antimicrobial susceptibility testing showed that the bacteria possessed a high level of resistance towards clinically used antibiotics. To investigate the interaction between these two microorganisms in influencing viral susceptibility and transmission in humans, guinea pigs were used as an infection model. Animals were inoculated with SIV or S. maltophilia alone or co-infected with SIV and S. maltophilia. The results showed that although no transmission among guinea pigs was observed, virus–bacteria co-infections resulted in higher virus titers in nasal washes and trachea and a longer virus shedding period.ConclusionsThis is the first report of influenza virus co-infection with S. maltophilia in the Chinese swine population. Increased replication of virus by co-infection with multidrug resistant bacteria might increase the infection rate of SIV in humans. The control of S. maltophilia in clinics will contribute to reducing the spread of SIV in pigs and humans.

Isolation and identification of emergent multidrug‐resistant Stenotrophomonas maltophilia from skin ulcers of Sarcoptes‐infested pigs

“…Antibiotic susceptibility testing revealed resistance of S. maltophilia towards multiple clinically used antibiotics. Hou et al 16 reported resistance of S. maltophilia to varied antibiotics like streptomycin, amoxicillin, novobiocin and cefotaxime, which corresponds to the results of this study. It is one of the most prominent features of this organism.…”

“…According to the study conducted by Mancini et al, 21 S. maltophilia was found to have a potentiating effect on the virulence of influenza virus in humans due to the secretion of protease (elastase). Similarly, Hou et al, 16 in an experimental study in guinea pigs to investigate the effect of S. maltophilia in swine influenza A virus (SIV)-infected mammals, maintained that coinfection with S. maltophilia enhanced the viral replication and could lead to a surge in the occurrence of human infections with SIV or SIV and S. maltophilia. The above-mentioned studies corroborate the zoonotic potential of S. maltophilia.…”

The porcine respiratory microbiome: recent insights and future challenges

“…Nevertheless, transbronchial BAL collection should be preferred to transoral [ 33 ]. Tracheobronchial swabbing is a less invasive alternative to BAL for LRT specimen collection that is well established in pig clinical practice, especially for detection of PRDC pathogens [ 66 , 67 ]. Collection of tracheobronchial swabs does not require anaesthesia, which is necessary prior to BAL sampling.…”

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…Another report of avian-origin H9N2 virus in Chinese swine was documented during 2006-2007 when four H9N2 virus isolates with closely related nucleotide sequences were retrieved from swine [75]. Each of the two different investigations reported 19 H1N1, one H1N2 and nine H3N2 virus isolates from Chinese swine during 2006-2009 [76,77]; the H1N2 virus and all nine isolates of H3N2 viruses were either double or triple-reassortant viruses [76].…”