Comparative Genome Sequencing of an Isogenic Pair of USA800 Clinical Methicillin-Resistant Staphylococcus aureus Isolates Obtained before and after Daptomycin Treatment Failure
Comparative Genome Sequencing of an Isogenic Pair of USA800 Clinical Methicillin-Resistant Staphylococcus aureus Isolates Obtained before and after Daptomycin Treatment Failure
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DOI：
10.1128/aac.01593-10
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发表时间：
2011-05-01
影响因子：
4.9
通讯作者：
Daum, Robert S.
中科院分区：
文献类型：
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作者：
Boyle-Vavra, Susan;Jones, Marcus;Daum, Robert S.
我们在这里描述了一位复发性耐甲氧西林金黄色葡萄球菌（MRSA）菌血症患者的临床达托霉素治疗失败，该患者在万古霉素和哌拉西林-他唑巴坦的经验治疗疗程失败后给予达托霉素治疗。我们有机会比较在开始使用达托霉素治疗之前和之后分别获得的一对对达托霉素敏感和耐药的MRSA分离株的基因组序列。两株分离株的基因型分别为USA800、ST5、SCCmec IV型、agr II型。尽管对万古霉素和达托霉素的敏感性降低，但耐达托霉素菌株的细胞壁厚度没有增加。通过对基因组序列的焦磷酸测序，我们在编码赖氨酸磷脂酰甘油转移酶的多肽抗性因子MprF的第10跨膜片段上发现了一个多态性（S337L）。这种酶以前已被证明通过在磷脂酰甘油中加入带正电的赖氨酸来促进细胞表面达托霉素的排斥。在达托霉素敏感菌株中，编码β -毒素的hlb开放阅读框（ORF）被一个前噬菌体打断；该噬菌体在达托霉素耐药分离株中缺失，hlb ORF得以恢复。耐药菌株中噬菌体的缺失也导致了毒力因子基因clpP、scn和sak的缺失。这是第一个使用焦磷酸测序来比较在人类达托霉素治疗失败期间获得的达托霉素敏感/耐药MRSA分离对的基因组的研究。
We describe here a clinical daptomycin treatment failure in a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in whom daptomycin was administered after a failed empirical treatment course with vancomycin and piperacillin-tazobactam. We had the opportunity to compare the genome sequences of an isogenic pair of daptomycin-susceptible and -resistant MRSA isolates obtained before and after initiation of daptomycin therapy, respectively. The genotype of both isolates was USA800, ST5, SCCmec type IV, agr type II. There was no increase in cell wall thickness in the daptomycin-resistant strain despite having decreased susceptibility to both vancomycin and daptomycin. By comparing the genome sequences by pyrosequencing, we identified a polymorphism (S337L) in the tenth transmembrane segment of the multiple peptide resistance factor, MprF, encoding lysyl phosphatidylglycerol transferase. This enzyme has been shown previously to promote repulsion of daptomycin at the cell surface by addition of positively charged lysine to phosphatidylglycerol. Also, the hlb open reading frame (ORF) encoding the beta-toxin was interrupted by a prophage in the daptomycin-susceptible strain; this phage was missing in the daptomycin-resistant isolate and the hlb ORF was restored. Loss of the phage in the resistant isolate also resulted in loss of the virulence factor genes clpP, scn, and sak. This is the first study to use pyrosequencing to compare the genomes of a daptomycin-susceptible/resistant MRSA isolate pair obtained during failed daptomycin therapy in humans.