Human methicillin‐sensitive Staphylococcus aureus biofilms: potential associations with antibiotic resistance persistence and surface polysaccharide antigens

Abstract

The development of persistent antibiotic resistance by human methicillin-sensitive Staphylococcus aureus (MSSA) strains and substantial association with poly-N-acetyl glucosamine (PNAG) in biofilms is reported in this investigation. Sixteen of 31 MSSA strains under study were found to have developed resistance to one or more antibiotics, with four strains, two of which did not produce biofilms, showing resistance to cefoxitin, undetectable by mecA amplification. Antibiotic resistance displayed by 13/14 biofilm-forming S. aureus isolates remained persistent for 4 weeks prior to reverting back to the original antibiotic susceptibility, prompting a suggestion of determining antibiograms for clinical S. aureus isolates subcultured from biofilms developed in vitro as well as planktonic subcultures prepared from the site of infection. While there was correlation of antibiotic resistance with biofilm formation confirming previous reports, this is the first time that persistence of the biofilm-associated antibiotic resistance by S. aureus as planktonic cells is reported. Among the two methods used for assessment of biofilm formation, the tissue culture plate (TCP) method revealed that almost all strains were strong or moderate biofilm producers whereas only 19/31 strains were biofilm producers using the Congo Red agar (CRA) method indicating the superiority of the TCP method in detecting biofilm producers. We also observed no association between biofilm formation and major capsule types. However, substantial, although not absolute, association of biofilm formation with PNAG was observed, warranting continued identification of additional surface-associated polysaccharide and/or protein antigens associated with biofilm formation for development of an effective vaccine against S. aureus infections regardless of capsular phenotype.

Detection of Alpha-Toxin and Other Virulence Factors in Biofilms of Staphylococcus aureus on Polystyrene and a Human Epidermal Model

“…aureus . Biofilms are defined as complex communities of bacteria encased in an extracellular polymeric matrix and biofilm formation is believed to contribute to bacterial virulence, reduced susceptibility to antibiotics [ 13 – 15 ] and reduced clearance by the immune system. Despite the plethora of studies examining the involvement of biofilm formation [ 16 ] and/or single virulence factors [ 17 , 18 ] in e.g.…”

Temporal expression ofagrB,cidA, andalsSin the early development ofStaphylococcus aureusUAMS-1 biofilm formation and the structural role of extracellular DNA and carbohydrates

“…Carbohydrates and surface proteins involved in adherence are known to be important in the EPS matrix and biofilm establishment (Toledo‐Arana et al ., ; Hall‐Stoodley et al ., ; Vergara‐Irigaray et al ., ). Poly‐β (1,6)‐N‐acetyl‐ d ‐glucosamine (PNAG) is a surface polysaccharide involved in biofilm accumulation and evasion of the host immune system in S. aureus and S. epidermidis (Izano et al ., ; Babra et al ., ), and it has been demonstrated that dispersin B, a PNAG‐degrading enzyme, was capable of detaching S. epidermidis biofilm, while DNase I primarily affected S. aureus biofilms (Izano et al ., ). Our data suggest that multiple EPS components need to be targeted to effectively disrupt biofilms.…”

High-level persistence of biofilm formation in in methicillin resistant Staphylococcus aureus

“…The plates were washed two times with distilled water and dried, then washed using 95% ethanol, and the optical density was determined using a microtiter plate reader at 570 nm (iMark Microplate Reader Sigma-Aldrich, Japan). Based on OD the isolate was referred to as weak (OD=0.480), moderate (OD=0.720) and strong (OD>0.720) biofilm producers (Babra et al 2014).…”

“…Compared to other pathogenic strains (MRSA) infections caused 20% death of all infections (Boucher and Corey, 2008). The resistivity of S. aureus infections is dependent on several factors among them, the most important factor is the ability of this organism to form biofilms (Babra et al, 2014).…”