Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Australia.
College of Health and Human Sciences, Charles Darwin University, Darwin, Northern Territory, Australia.
PLoS One. 2021 Feb 5;16(2):e0245790. doi: 10.1371/journal.pone.0245790. eCollection 2021.
The study objective was to reveal reservoirs potentially leading to Staphylococcus aureus infections in haemodialysis clinic clients in the tropical north of the Australian Northern Territory (NT). This client population are primarily Aboriginal Australians who have a greater burden of ill health than other Australians. Reservoir identification will enhance infection control in this client group, including informing potential S. aureus decolonisation strategies.
The study participants were 83 clients of four haemodialysis clinics in the Darwin region of the NT, and 46 clinical staff and researchers who had contact with the clinic clients. The study design was longitudinal, encompassing swabbing of anatomical sites at two month intervals to yield carriage isolates, and also progressive collection of infection isolates. Swab sampling was performed for all participants, and infection isolates collected for dialysis clients only. Analysis was based on the comparison of 139 carriage isolates and 27 infection isolates using whole genome sequencing. Genome comparisons were based on of 20,651 genome-wide orthologous SNPs, presence/absence of the mecA and pvl genes, and inferred multilocus sequence type and clonal complex. Pairs of genomes meeting the definition of "not discriminated" were classed as defining potential transmission events. The primary outcome was instances of potential transmission between a carriage site other than a skin lesion and an infection site, in the same individual. Three such instances were identified. Two involved ST762 (CC1) PVL- MRSA, and one instance ST121 PVL+ MSSA. Three additional instances were identified where the carriage strains were derived from skin lesions. Also identified were six instances of potential transmission of a carriage strains between participants, including transmission of strains between dialysis clients and staff/researchers, and one potential transmission of a clinical strain between participants. There were frequent occurrences of longitudinal persistence of carriage strains in individual participants, and two examples of the same strain causing infection in the same participants at different times. Strains associated with infections and skin lesions were enriched for PVL and mecA in comparison to strains associated with long term carriage.
This study indicated that strains differ with respect to propensity to stably colonise sites such as the nose, and cause skin infections. PVL+ strains were associated with infection and skin lesions and were almost absent from the carriage sites. PVL- MRSA (mainly CC1) strains were associated with infection and also with potential transmission events involving carriage sites, while PVL- MSSA were frequently observed to stably colonise individuals without causing infection, and to be rarely transmitted. Current clinical guidelines for dialysis patients suggest MRSA decolonisation. Implementation in this client group may impact infections by PVL- MRSA, but may have little effect on infection by PVL+ strains. In this study, the PVL+ strains were predominant causes of infection but rarely colonised typical carriage sites such as the nose, and in the case of ST121, were MSSA. The important reservoirs for infection by PVL+ strains appeared to be prior infections.
本研究旨在揭示澳大利亚北部地区（北领地）热带地区血液透析诊所患者中可能导致金黄色葡萄球菌感染的储层。该患者群体主要是澳大利亚原住民，他们的健康状况比其他澳大利亚人更为严重。储层的确定将增强对该患者群体的感染控制，包括为金黄色葡萄球菌去定植策略提供信息。
研究对象为北领地达尔文地区四个血液透析诊所的 83 名患者，以及 46 名与诊所患者有接触的临床工作人员和研究人员。研究设计为纵向研究，包括每两个月对解剖部位进行拭子取样以获得携带分离株，以及逐步收集感染分离株。对所有参与者进行拭子采样，仅对透析患者采集感染分离株。分析基于比较 139 个携带分离株和 27 个感染分离株，使用全基因组测序。基因组比较基于 20651 个全基因组同源直系同源 SNP、mecA 和 pvl 基因的存在/缺失情况，以及推断的多位点序列型和克隆复合体。符合“未区分”定义的基因组对被归类为定义潜在传播事件。主要结局是同一个体中，除皮肤病变外的其他携带部位与感染部位之间的潜在传播事件。确定了三个这样的事件。两个涉及 ST762（CC1）PVL-MRSA，一个涉及 ST121 PVL+ MSSA。还确定了三个携带菌株来自皮肤病变的潜在传播事件。还确定了六个携带菌株在参与者之间的潜在传播事件，包括透析患者与工作人员/研究人员之间的菌株传播，以及参与者之间的一个临床菌株的潜在传播。在个体参与者中，携带菌株的纵向持续存在频繁发生，两个相同的菌株在同一参与者的不同时间引起感染。与长期携带相关的感染和皮肤病变相关的菌株富集了 PVL 和 mecA，而与感染和皮肤病变相关的菌株则很少。
本研究表明，菌株在稳定定植鼻等部位的能力以及引起皮肤感染的能力上存在差异。PVL+菌株与感染和皮肤病变有关，几乎不存在于携带部位。PVL-MRSA（主要是 CC1）菌株与感染以及涉及携带部位的潜在传播事件有关，而 PVL-MSSA 则经常观察到稳定定植于个体而不引起感染，并且很少传播。目前针对透析患者的临床指南建议对 MRSA 进行去定植。在该患者群体中实施可能会影响 PVL-MRSA 引起的感染，但对 PVL+菌株引起的感染影响不大。在本研究中，PVL+菌株是感染的主要原因，但很少定植于典型的携带部位，如鼻子，而在 ST121 中，它们是 MSSA。PVL+菌株感染的重要储层似乎是先前的感染。
