Azithromycin Reduces the Production of α-hemolysin and Biofilm Formation in Staphylococcus aureus

Abstract

Staphylococcus aureus causes a broad range of life-threatening diseases in humans. This bacterium produces a large number of extracellular virulence factors that are closely associated with specific diseases which are controlled by quorum sensing. In this study, we show that azithromycin was active against methicillin-resistant Staphylococcus aureus (MRSA) strains with MICs ranged from 32 to 64 lg/mL. Azithromycin at subinhibitory concentration, markedly reduced the production of a-hemolysin at (1/16MIC, 1/8MIC) and biofilm formation at (1/16MIC, 1/8MIC), respectively. The results indicated that sub-inhibitory concentrations of azithromycin decreased the production of a-hemolysin and biofilm formation in MRSA in a dose-dependent manner. Therefore, azithromycin may be useful in the treatment of a-hemolysin producing and biofilm formation MRSA infections.Staphylococcus aureus is found among the normal human skin flora and it is an important pathogen of humans, causing diseases ranging from superficial skin and wound infections to severe illnesses such as septicaemia, endocarditis and toxic shock syndrome [1]. S. aureus is particularly a problem in hospitals because it spreads easily in these environments and causes potentially fatal infections in immunocompromised hospital patients. S. aureus cause disease through the production of virulence factors. These factors include adhesins, exotoxins, enterotoxins, hemolysins, and leukocidin, as well as proteases that enable the bacteria to spread within the host [2,3]. Quorum sensing (QS) regulates expression of genes encoding these virulence factors and biofilm formation. Strains defective in their ability to form a biofilm or produce toxins show diminished virulence [4], suggesting that a novel approach for therapy development would be to interfere with the production of virulence factors [5][6][7]. Azithromycin (AZM) is one of the macrolides antibiotics, and it is a broad-spectrum macrolide antibiotic effective against Gram-positive, Gram-negative, and atypical bacteria and has anti-inflammatory characteristics [8]. The purpose of this study is to assess the effect of azithromycin, used as a quorum-sensing inhibitor, for decrease the production of QS associated virulence factors and biofilm formation in Staphylococcus aureus.Two different clinical bacterial strains of methicillinresistant Staphylococcus aureus (MRSA) 10 and 21 were collected from different patients hospitalized at Lishui People's Hospital, Zhejiang province. S. aureus strains was identified biochemically from routinely obtained specimens by means of the Vitek ATB Expression System, version 2.7.8 (BioMe'rieux Deutschland GmbH, Nürtin-gen, Germany), which uses 32 biochemical reactions. Bacterial isolates were stored as suspensions in LB medium containing 12.5 % (vol/vol) glycerol at -70°C until tests were performed. S. aureus MRSA 10, 21 single colony was inoculated into LB media and cultured overnight at 37. Overnight culture was subcultured (1:100) into test tubes with fresh LB medium in tripl...

3-Amino-4-aminoximidofurazan derivatives: small molecules possessing antimicrobial and antibiofilm activity againstStaphylococcus aureusandPseudomonas aeruginosa

“…Minimum inhibitory concentrations of PI1-4 along with azithromycin (AZM) (Gui et al 2014) and tobramycin (TBM) (Du et al 2015) were performed against Staph. aureus and Ps.…”

Multiplicity of Quorum Quenching Enzymes: A Potential Mechanism to Limit Quorum Sensing Bacterial Population

“…possess the unique ability to produce antibiotics and other pathogenicity factors such as proteases, elastase, rhamnolipid, pyocyanin, superoxide dismutases for their defense against reactive oxygen species (ROS), to evade the immune response, and degrade surfactant proteins [9]. Most of these pathogenicity factors are produced through the phenomenon of quorum sensing (QS) [10,11]. QS is a cell density dependent phenomenon, which operates through signal molecules.…”

Bacteria in the respiratory tract—how to treat? Or do not treat?

“…Although several antimicrobials alter toxin production, as extensively reported for CA-MRSA, 43,44,128,129 an alternative approach to conventional antimicrobials, aimed at killing the bacteria (as are almost all available antibiotics), is based on targeting the functions essential for infection, such as virulence factors required to cause host damage and disease, without impairing microbial growth. Although antibody therapies in the form of serum were the first effective antimicrobials, the use of purified monoclonal antibodies (mAb) has only recently reached the field of infectious diseases.…”