Fitness cost: a bacteriological explanation for the demise of the first international methicillin-resistant Staphylococcus aureus epidemic
Fitness cost: a bacteriological explanation for the demise of the first international methicillin-resistant Staphylococcus aureus epidemic
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DOI：
10.1093/jac/dks051
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发表时间：
2012-06-01
影响因子：
5.2
通讯作者：
Frimodt-Moller, Niels
中科院分区：
文献类型：
--
作者：
Nielsen, Karen L.;Pedersen, Thomas M.;Frimodt-Moller, Niels
丹麦和其他几个国家在1965 - 75年期间经历了耐甲氧西林金黄色葡萄球菌（MRSA）的第一次流行，其由噬菌体复合物83 A的多重耐药分离株引起。在丹麦，这些MRSA分离株几乎完全消失，被其他噬菌体类型所取代，主要是青霉素抗性。我们调查了这种流行病的分离株是否与适应性成本有关，我们采用了一个数学模型来询问这些适应性成本是否会导致观察到的频率降低。金黄色葡萄球菌从丹麦已储存自1957年以来。我们选择了40 S。金黄色葡萄球菌分离株属于噬菌体复合体83 A，基于SPA型的克隆复合体8，分离时间从1957年至1980年不等，具有不同的细菌谱，包括甲氧西林耐药和敏感分离株。每个分离株的相对适合度在生长竞争试验中与参考分离株进行测定。对于所研究的MRSA分离株，确定了215的显著适合度成本。抗生素抗性数量与相对适合度呈显著负相关。多元回归分析发现健身和存在的mecA或链霉素耐药性之间显着独立的负相关。数学建模证实，健身成本的大小进行这些分离株可能会导致在类似的时间跨度内看到在丹麦的MRSA患病率的消失。我们提出了一个显着的健身成本的阻力作为主要的细菌学解释的多重耐药复杂的83 A MRSA在丹麦的消失后，减少抗生素的使用。
Denmark and several other countries experienced the first epidemic of methicillin-resistant Staphylococcus aureus (MRSA) during the period 196575, which was caused by multiresistant isolates of phage complex 83A. In Denmark these MRSA isolates disappeared almost completely, being replaced by other phage types, predominantly only penicillin resistant. We investigated whether isolates of this epidemic were associated with a fitness cost, and we employed a mathematical model to ask whether these fitness costs could have led to the observed reduction in frequency.Bacteraemia isolates of S. aureus from Denmark have been stored since 1957. We chose 40 S. aureus isolates belonging to phage complex 83A, clonal complex 8 based on spa type, ranging in time of isolation from 1957 to 1980 and with varyous antibiograms, including both methicillin-resistant and -susceptible isolates. The relative fitness of each isolate was determined in a growth competition assay with a reference isolate.Significant fitness costs of 215 were determined for the MRSA isolates studied. There was a significant negative correlation between number of antibiotic resistances and relative fitness. Multiple regression analysis found significantly independent negative correlations between fitness and the presence of mecA or streptomycin resistance. Mathematical modelling confirmed that fitness costs of the magnitude carried by these isolates could result in the disappearance of MRSA prevalence during a time span similar to that seen in Denmark.We propose a significant fitness cost of resistance as the main bacteriological explanation for the disappearance of the multiresistant complex 83A MRSA in Denmark following a reduction in antibiotic usage.