2 research outputs found
Induction of In Vitro Resistance to Penicillin in Viridans Group Streptococci and Its Effect on Susceptibility Pattern of Other Antimicrobial Agents
Background: The development of resistance to
penicillin in Viridans Group Streptococci (VGS)
during therapy has been reported. However, the in vitro
development of resistance to penicillin or other
antimicrobial agents in VGS is mostly overlooked and
rarely reported. Aim & Objectives: To induce in vitro
resistance to penicillin in VGS and to study its effect on
susceptibility pattern of other structurally related
(Beta–lactams) and unrelated antimicrobial agents.
Material and Methods: Four isolates of VGS
susceptible to all antimicrobial agents were
manipulated in vitro to induce resistance to penicillin
by sequential exposure to increasing concentrations of
penicillin. Results: Increase in MIC values of
penicillin from 0.06-0.12 µg/ml to 2-32 µg/ml was
observed indicating development of resistance to
penicillin. A significant increase in Minimum
Inhibitory Concentration (MIC) values of ampicillin
and slight increase in MIC values of other
antimicrobial agents in some isolates was also noted.
Conclusions: Exposure to increasing concentrations of
penicillin can promote the development of resistance
to penicillin and cross-resistance to other
antimicrobial agents suggesting its mutagenic role
Susceptibility, Resistance and Treatment Strategy for Infections Caused by Viridans Group Streptococci - A Review
Viridans Group Streptococci (VGS) were considered to
be commensal organisms of low virulence. Their major
disease associations were formerly limited to dental
caries and infective endocarditis. Over the last several
years, these bacteria have emerged as significant
pathogens associated with gingivitis, periodontitis,
bacteremia, meningitis, pneumonia and a variety of
infections in neonates. Although penicillin remains the
drug of choice in the treatment of infections caused by
VGS, drug tolerance and clinical therapeutic failures
have been reported. Different studies in recent past
show that there is an alarming increase in resistance in
VGS to various antimicrobial agents. Increase in the
incidence of VGS with multiple drug resistance to
penicillin and other agents suggest for periodic
surveillance of antimicrobial susceptibility among
VGS in order to guide appropriate antimicrobial
therapy and to develop an appropriate treatment
strategy for various infections caused by VGS. The
development of appropriate treatment strategy not only
helps in effective management but also helps to
monitor further spread of resistant pathogens