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Synergistic, collaterally sensitive ?-lactam combinations suppress resistance in MRSA.

ABSTRACT: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent multidrug-resistant pathogens worldwide, exhibiting increasing resistance to the latest antibiotic therapies. Here we show that the triple ?-lactam combination meropenem-piperacillin-tazobactam (ME/PI/TZ) acts synergistically and is bactericidal against MRSA subspecies N315 and 72 other clinical MRSA isolates in vitro and clears MRSA N315 infection in a mouse model. ME/PI/TZ suppresses evolution of resistance in MRSA via reciprocal collateral sensitivity of its constituents. We demonstrate that these activities also extend to other carbapenem-penicillin-?-lactamase inhibitor combinations. ME/PI/TZ circumvents the tight regulation of the mec and bla operons in MRSA, the basis for inducible resistance to ?-lactam antibiotics. Furthermore, ME/PI/TZ subverts the function of penicillin-binding protein-2a (PBP2a) via allostery, which we propose as the mechanism for both synergy and collateral sensitivity. Showing in vivo activity similar to that of linezolid, ME/PI/TZ demonstrates that combinations of older ?-lactam antibiotics could be effective against MRSA infections in humans.

SUBMITTER: Gonzales PR

PROVIDER: S-EPMC4618095 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Synergistic, collaterally sensitive β-lactam combinations suppress resistance in MRSA.

Gonzales Patrick R PR Pesesky Mitchell W MW Bouley Renee R Ballard Anna A Biddy Brent A BA Suckow Mark A MA Wolter William R WR Schroeder Valerie A VA Burnham Carey-Ann D CA Mobashery Shahriar S Chang Mayland M Dantas Gautam G

Nature chemical biology 20150914 11

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent multidrug-resistant pathogens worldwide, exhibiting increasing resistance to the latest antibiotic therapies. Here we show that the triple β-lactam combination meropenem-piperacillin-tazobactam (ME/PI/TZ) acts synergistically and is bactericidal against MRSA subspecies N315 and 72 other clinical MRSA isolates in vitro and clears MRSA N315 infection in a mouse model. ME/PI/TZ suppresses evolution of resistance in MRSA ...[more]

PMID: 26368589

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Project description:Bacterial infections remain the leading killer worldwide which is worsened by the continuous emergence of antibiotic resistance. In particular, methicillin-sensitive (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) are prevalent and the latter can be difficult to treat. The traditional strategy of novel therapeutic drug development inevitably leads to emergence of resistant strains, rendering the new drugs ineffective. Therefore, rejuvenating the therapeutic potentials of existing antibiotics offers an attractive novel strategy. Plectasin, a defensin antimicrobial peptide, potentiates the activities of other antibiotics such as ?-lactams, aminoglycosides and glycopeptides against MSSA and MRSA. We performed in vitro and in vivo investigations to test against genetically diverse clinical isolates of MSSA (n = 101) and MRSA (n = 115). Minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. The effects of combining plectasin with ?-lactams, aminoglycosides and glycopeptides were examined using the chequerboard method and time kill curves. A murine neutropenic thigh model and a murine peritoneal infection model were used to test the effect of combination in vivo. Determined by factional inhibitory concentration index (FICI), plectasin in combination with aminoglycosides (gentamicin, neomycin or amikacin) displayed synergistic effects in 76-78% of MSSA and MRSA. A similar synergistic response was observed when plectasin was combined with ?-lactams (penicillin, amoxicillin or flucloxacillin) in 87-89% of MSSA and MRSA. Interestingly, no such interaction was observed when plectasin was paired with vancomycin. Time kill analysis also demonstrated significant synergistic activities when plectasin was combined with amoxicillin, gentamicin or neomycin. In the murine models, plectasin at doses as low as 8 mg/kg augmented the activities of amoxicillin and gentamicin in successful treatment of MSSA and MRSA infections. We demonstrated that plectasin strongly rejuvenates the therapeutic potencies of existing antibiotics in vitro and in vivo. This is a novel strategy that can have major clinical implications in our fight against bacterial infections.

Project description:The purpose of this study is to characterize adverse events (AEs) of clinical interest reported with ceftolozane-tazobactam and ceftazidime-avibactam, as an aid in monitoring patients affected by severe multidrug-resistant Gram-negative infections. We queried the worldwide FDA Adverse Event Reporting System (FAERS) and performed disproportionality analysis, selecting only designated medical events (DMEs) where ceftolozane-tazobactam and ceftazidime-avibactam were reported as suspect. Serious neurological AEs were further investigated. The reporting odds ratios were calculated, deemed significant by the lower limit of the 95% confidence interval (LL95% CI) > 1. All other drugs/events recorded in FAERS and cephalosporins showing clinical evidence of neurological AEs were respectively selected as comparator for analysis of DMEs and neurotoxicity. Qualitative analysis including case-by-case assessment and deduplication was also performed. Overall, 654 and 506 reports mentioning respectively ceftolozane-tazobactam and ceftazidime-avibactam were found, with DMEs accounting respectively for 13.1% and 10.9% of cases. Agranulocytosis (N = 12; LL95% CI = 12.40) and pancytopenia (14; 6.18) emerged as unexpected AEs with ceftolozane-tazobactam, while acute pancreatitis (7; 8.63) was an over-reported unexpected DME with ceftazidime-avibactam. After deduplication, four unequivocally different cases of agranulocytosis with ceftolozane-tazobactam were retained, occurring on average after 8.8 days. Causality was probable and possible respectively in three and one case. Among neurological AEs exhibiting significant disproportionality, encephalopathy with both antibiotics and mental status changes with ceftazidime-avibactam were retained in at least three cases after deduplication. Although rare, clinicians should monitor high-risk patients (i.e. individuals affected by haematological malignances, HIV infection, or treated with concomitant myelotoxic agents) for early unexpected occurrence of agranulocytosis with ceftolozane-tazobactam.

Dataset Information

Synergistic, collaterally sensitive ?-lactam combinations suppress resistance in MRSA.

Publications

Synergistic, collaterally sensitive β-lactam combinations suppress resistance in MRSA.

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