Serological versus molecular typing of surface-associated immune evading polysaccharide antigens-based phenotypes of Staphylococcus aureus

Abstract

The aim of this study was to compare the performance of serological versus molecular typing methods to detect capsular polysaccharide (CP) and surface-associated polysaccharide antigen 336 phenotypes of Staphylococcus aureus isolates. Molecular typing of CP types 1, 5 and 8 was carried out using PCR, whereas serological typing of CP1, 2, 5, 8 and antigen 336 was carried out by slide agglutination using specific antisera. By genotyping, 14/31 strains were CP8 positive, 12/31 strains were CP5 and the remaining 6/31 isolates were non-typable (NT). One isolate was positive for both CP5 and CP8 by PCR, but was confirmed as CP8 type serologically. Detection of CP2 and type 336 by PCR was not possible because specific primers were either not available or non-specific. Using serotyping, 14/31 strains were CP8 positive, 11/31 CP5 positive and 2/31 positive for antigen 336. The remaining four S. aureus isolates were serologically NT. However, three of four NT and two 336-positive S. aureus isolates were encapsulated as determined by light microscopy after capsular staining. This discovery was surprising and warrants further investigations on the identification and characterization of additional capsular phenotypes prevalent among S. aureus clinical isolates. It was concluded that serological typing was a better method than molecular typing for use in epidemiological investigations based upon the distribution of surface-associated polysaccharide antigens-based phenotypes.

Molecular Characterization of Staphylococcus Aureus Isolates Recovered From Children With Otitis Media in Alexandria Hospitals, Egypt

“…Therefore, in our study all S. aureus isolates were characterized by the detection of cap5 and cap8 specific genes. The results showed that cap8 was more predominant than cap5; this finding was consistent with another study in Western Australia which reported a higher percentage of cap8 than cap5 in S. aureus isolates (45.2% and 38.7% respectively) 11 . Another study in Nigeria showed that cap8 and were present in 94% and 6% of S. aureus isolates respectively 46 .…”

“…S. aureus produces several virulence factors including capsular polysaccharides (CP) which protect it from complement binding and subsequent phagocytic killing by neutrophils 10,11 . On the contrary, anti-capsular antibodies released by the host can opsonize the pathogen, augmenting the host immune defense mechanisms 10,12 .…”

Mammary Gland Pathology Subsequent to Acute Infection with Strong versus Weak Biofilm Forming Staphylococcus aureus Bovine Mastitis Isolates: A Pilot Study Using Non-Invasive Mouse Mastitis Model

“…Development of acute mastitis was measured by the level of mammary tissue damage based upon clinical manifestations, histopathology, and the production of inflammatory cytokines. The only differences between the 2 isolates used in this investigation are the detection of ica A and ica D genes encoding production of PNAG, previously reported to be associated with biofilm formation [ 67 , 68 ] and the spa and clfA genes encoding the production of protein A and clfA clumping factor A respectively in the strong biofilm forming strain 51, which were undetectable in the weak biofilm forming S . aureus isolate/strain 104 ( Table 1 ).…”

Detection and antibiotic resistance pattern of Staphylococcus aureusand (MRSA) isolated from healthcare workers Nares at three Gaza hospitals, Palestine

“…Many previous studies reported the majority of human S. aureus strains (70-80%) possess either cap5 and/or cap8 [44]. Nevertheless, a study from USA revealed that all pediatric isolates contained either cap5 or cap8 genes [45],while a recent study from Australia shows absence of cap8 and cap5 (non-typable strains) in 19.4% of their isolates [44]. Capsular polysaccharide plays an important role in the pathogenicity and immunogenicity of S. aureus, notably as antiphagocytic factor but also as a vaccine target.…”