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Group B streptococcal pharyngitis in the compromised adult: therapeutic considerations
Abstract:
Group B streptococci (GBS) have been infrequently recognized as a cause of pharyngitis. We report three cases of GBS pharyngitis in patients with underlying diseases, two of whom were treated with and responded incompletely to oral beta-lactam antibiotics. The susceptibility of 20 clinical isolates of GBS was tested by a broth dilution method to six antibiotics which could conceivably be used in the therapy of GBS pharyngitis. Penicillin G, clindamycin, and erythromycin were most active with mean minimal inhibitory concentrations (MIC) of 0.06 μg/ml or less. Rifampin and cefaclor were least active with mean MICs of 0.71 ug/ml or more. Ampicillin was intermediate in its activity. Therapy traditionally used for Group A streptococcal (GAS) pharyngitis may, at times, be suboptimal for GBS pharyngitis in compromised patients. This may be due to higher minimal bactericidal concentrations (MBC) of GBS than GAS, to inadequate penetration of penicillins into pharyngeal tissues or to host factors. It is suggested that GBS can cause pharyngitis in adults, particularly the compromised patient, and that in cases where there is a poor response to penicillin or ampicillin therapy, alternative drugs (erythromycin or clindamycin) may be used.
Insights
Group B streptococci (GBS) can cause pharyngitis, especially in immunocompromised adults. Standard beta-lactam antibiotics may be ineffective, suggesting alternative treatments like erythromycin or clindamycin for GBS pharyngitis.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Medicine
Background:
- Group B streptococci (GBS) are not commonly recognized as a cause of pharyngitis.
- Pharyngitis caused by GBS may present challenges in immunocompromised patients.
- Incomplete treatment responses to beta-lactam antibiotics have been observed in GBS pharyngitis cases.
Purpose of the Study:
- To investigate the clinical presentation and antibiotic susceptibility of Group B streptococci (GBS) causing pharyngitis.
- To evaluate the efficacy of various antibiotics against GBS clinical isolates.
- To inform treatment strategies for GBS pharyngitis, particularly in compromised hosts.
Main Methods:
- Case reports of three patients with GBS pharyngitis were analyzed.
- Antibiotic susceptibility testing using broth dilution was performed on 20 clinical GBS isolates.
- Minimal inhibitory concentrations (MICs) were determined for penicillin G, ampicillin, cefaclor, clindamycin, erythromycin, and rifampin.
Main Results:
- Penicillin G, clindamycin, and erythromycin demonstrated high activity against GBS (mean MIC ≤ 0.06 μg/ml).
- Rifampin and cefaclor showed lower activity (mean MIC ≥ 0.71 μg/ml), with ampicillin being intermediate.
- Two patients with underlying diseases showed incomplete response to oral beta-lactam antibiotics.
Conclusions:
- Group B streptococci can cause pharyngitis in adults, particularly those who are immunocompromised.
- Traditional therapies for Group A streptococcal pharyngitis may be suboptimal for GBS pharyngitis.
- Erythromycin or clindamycin may be considered as alternative treatments for GBS pharyngitis unresponsive to penicillin or ampicillin.