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Ruppen C, Mercier T, Grandgirard D, Leib SL, El Haj C, Murillo O, Decosterd L, Sendi P. Is Penicillin Plus Gentamicin Synergistic Against Sessile Group B Streptococcal Isolates? An in Vivo Study With an Experimental Model of Foreign-Body Infection. Front Microbiol 2018; 9:919. [PMID: 29867830 PMCID: PMC5962661 DOI: 10.3389/fmicb.2018.00919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 04/20/2018] [Indexed: 11/13/2022] Open
Abstract
The rate of invasive group B Streptococcus (GBS) infections is steadily increasing, particularly in older persons and in adults with diabetes and other comorbidities. This population includes persons with a foreign body (e.g., who have undergone arthroplasty). In a rat tissue cage model, we evaluated the efficacy of adjunctive gentamicin (GEN) administered systemically (5 mg/kg body weight) every 24 h, or locally (12.5 mg/L tissue cage concentration) every 24 or 72 h, in combination with penicillin (PEN) administered systemically (250,000 IU/kg body weight three times per day). The efficacy was evaluated on two different sessile forms of GBS: transition (i.e., in between planktonic and biofilm) and biofilm. After 3 days of treatment, the mean bacterial load reduction of transition-form GBS was greater in all PEN-GEN combination groups than in the PEN monotherapy group (P ≤ 0.03). The 6-day regimen decreased the bacterial load significantly in comparison to the 3-day regimen, irrespective of growth form and adjunctive GEN (P < 0.01). After 6 days of treatment, the mean reduction in transition-form GBS was greater with PEN plus GEN administered locally every 24 h than with PEN monotherapy (P = 0.03). These results were not confirmed with biofilm GBS. The difference in mean bacterial load reduction between all PEN-GEN and PEN monotherapy groups was <100 CFU/mL. Hence, synergy criteria were not fulfilled. Adjunctive systemic GEN consists of potential side effects and showed poor efficacy in this study. Combining systemic PEN and local GEN has a potential application in the treatment of streptococcal implant-associated infections.
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Affiliation(s)
- Corinne Ruppen
- Institute for Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Thomas Mercier
- Service and Laboratory of Clinical Pharmacology, Department of Laboratories, Lausanne University Hospital, Lausanne, Switzerland
| | - Denis Grandgirard
- Institute for Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stephen L. Leib
- Institute for Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Cristina El Haj
- Laboratory of Experimental Infection, Infectious Diseases Service, Bellvitge Biomedical Research Institute–Hospital Universitari Bellvitge, Barcelona, Spain
| | - Oscar Murillo
- Laboratory of Experimental Infection, Infectious Diseases Service, Bellvitge Biomedical Research Institute–Hospital Universitari Bellvitge, Barcelona, Spain
| | - Laurent Decosterd
- Service and Laboratory of Clinical Pharmacology, Department of Laboratories, Lausanne University Hospital, Lausanne, Switzerland
| | - Parham Sendi
- Institute for Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
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