Macrolide Resistance Genes and Virulence Factors of Common Viridans Streptococci Species Colonizing Oral Cavities of Patients in Jordan

The viridans group streptococci (VGS) are the most common pathogens isolated from human dental plaque. They arecapable of causing several infections as well as invasivediseases; dental caries, purulent infections of oral and otherbody sites such as blood sepsis and infectiveendocarditis,despite the fact that they are generally considered to be of lowpathogenic potential. In particular, VGS are a frequentcause of native valve endocarditis in immunocompetentindividuals and endocarditis or sepsis in patients withneutropenia. It is well known that streptococcalendocarditis isa life- threatening disease that requires a long period ofeffective treatment.Recently, VGS have attracted attention due to their abilityto act as reservoirs for antibiotic resistance genes and totransfer their resistance factors to more pathogenic organismslike Streptococcus pneumoniae and Streptococcus pyogenes[2,6]. In thepast, VGS werenearlyuniformly susceptible toβ-lactamantimicrobialagents,aminoglycosides,tetracyclines,and macrolides. Several recentlypublished studies fromdifferent countries reported that antimicrobial resistanceisemerging in VGS isolates, mostly tovpenicillinandmacrolides.Thisresistancepatternhas also been found frequentlyin species of VGS;S.mitis, S.mutans, and S. salivarius , whichare important part of the normal oral flora ofchildren andadults. In addition, these species are commonly associated

with various clinical infections.

Therefore, it is important to follow the development ofresistancepatterns in these species of streptococci , in order toselect the proper drug in chemoprophylaxis.This study aims to investigate the common species of VGSin oral cavity of dental treated patients in Jordan, and todetermine the susceptibility of isolates to erythromycin inassociation with certain specific potential virulence factors.Collection of specimensPatients were recruited from the Oral Diagnosis Clinic at theDental Department, Jordan University Hospital(UJH) inAmman- Jordan, over the period from April to June, 2011. Allparticipants signed an informed consent form includingparents of examined children. The following demographicdata were collected: name, age, sex, and a recent history ofantibiotic treatment.Patients received antibiotics within thelast 4 weeks were excluded from the study. All investigatedpatients were selected randomly according to their admission

for general dental examination. Sterile swabs were used tocollect plaque samples from thebuccal surfaces of upper andower first molars. The swabs were placed in brain heartinfusionbroth (Oxoid, England) and transferred immediatelyfor culture at theMicrobiology Research Laboratory at theFaculty of Medicine, University of Jordan. This study wasapproved by the ethics committee of The University of JordanHospital (UJH), research committee and of the Faculty ofMedicine, and scientific research Deanship of The JordanUniversity.