Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Genética Molecular de Microrganismos, Rio de Janeiro, RJ, Brasil.
Universidade Federal de Roraima, Boa Vista, RR, Brasil.
Mem Inst Oswaldo Cruz. 2020 Nov 6;115:e200371. doi: 10.1590/0074-02760200371. eCollection 2020.
Acinetobacter baumannii outbreaks have been associated with pandemic International Clones (ICs), but the virulence factors involved with their pathogenicity are sparsely understood. Pigment production has been linked with bacterial pathogenicity, however, this phenotype is rarely observed in A. baumannii.
This study aimed to characterise the reddish-brown pigment produced by A. baumannii strains, and to determine its biosynthetic pathway by genomic approaches.
Pigment characterisation and antimicrobial susceptibility were conducted by phenotypic tests. The clonal relationship was obtained by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The genome of an A. baumannii was obtained for characterisation of genes involved with pigment production.
The pyomelanin was the pigment produced by A. baumannii. Strains were extensively drug resistant and belonged to the IC-5/ST79. The pyomelanin biosynthetic pathway was determined and presented a particular architecture concerning the peripheral (tyrB, phhB and hpd) and central (hmgB, hmgC and hmgR) metabolic pathway genes. The identification of a distant HmgA homologue, probably without dioxygenase activity, could explain pyomelanin production. Virulence determinants involved with adherence (csuA/BABCDE and a T5bSS-carrying genomic island), and iron uptake (basABCDEFGHIJ, bauABCDEF and barAB) were characterised.
There is a biosynthetic pathway compatible with the pyomelanin production observed in persistent A. baumannii IC-5 strains.
鲍曼不动杆菌的爆发与流行的国际克隆（ICs）有关，但与它们的致病性相关的毒力因子知之甚少。色素的产生与细菌的致病性有关，但在鲍曼不动杆菌中很少观察到这种表型。
本研究旨在描述鲍曼不动杆菌菌株产生的红棕色色素，并通过基因组方法确定其生物合成途径。
通过表型试验进行色素特征和抗菌药物敏感性分析。通过脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）获得克隆关系。对一株鲍曼不动杆菌的基因组进行了特征分析，以确定与色素产生有关的基因。
鲍曼不动杆菌产生的是脓黑素。菌株具有广泛的耐药性，属于 IC-5/ST79。确定了脓黑素生物合成途径，并呈现出与外围（tyrB、phhB 和 hpd）和中央（hmgB、hmgC 和 hmgR）代谢途径基因有关的特殊结构。鉴定出一个遥远的 HmgA 同源物，可能没有双加氧酶活性，可以解释脓黑素的产生。与粘附（csuA/BABCDE 和携带 T5bSS 的基因组岛）和铁摄取（basABCDEFGHIJ、bauABCDEF 和 barAB）有关的毒力决定因素也得到了描述。
存在与持久性鲍曼不动杆菌 IC-5 菌株中观察到的脓黑素产生相兼容的生物合成途径。
