Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, GO, Brazil.
BMC Infect Dis. 2013 Dec 5;13:572. doi: 10.1186/1471-2334-13-572.
Nasal colonization with coagulase-negative Staphylococcus (CoNS) has been described as a risk factor for subsequent systemic infection. In this study, we evaluated the genetic profile of CoNS isolates colonizing the nares of children admitted to a neonatal intensive care unit (NICU).
We assessed CoNS carriage at admittance and discharge among newborns admitted to a NICU from July 2007 through May 2008 in one of the major municipalities of Brazil. Isolates were screened on mannitol salt agar and tryptic soy broth and tested for susceptibility to antimicrobials using the disc diffusion method. Polymerase chain reaction (PCR) was used to determine the species, the presence of the mecA gene, and to perform SCCmec typing. S. epidermidis and S. haemolyticus isolated from the same child at both admission and discharge were characterized by PFGE.
Among 429 neonates admitted to the NICU, 392 (91.4%) had nasal swabs collected at both admission and discharge. The incidence of CoNS during the hospitalization period was 55.9% (95% confidence interval [CI]: 50.9-60.7). The most frequently isolated species were S. haemolyticus (38.3%) and S.epidermidis (38.0%). Multidrug resistance (MDR) was detected in 2.2% and 29.9% of the CoNS isolates, respectively at admittance and discharge (p = 0.053). The mecA gene was more prevalent among strains isolated at discharge (83.6%) than those isolated at admission (60%); overall, SCCmec type I was isolated most frequently. The length of hospitalization was associated with colonization by MDR isolates (p < 0.005). Great genetic diversity was observed among S. epidermidis and S. haemolyticus.
NICU represents an environment of risk for colonization by MDR CoNS. Neonates admitted to the NICU can become a reservoir of CoNS strains with the potential to spread MDR strains into the community.
凝固酶阴性葡萄球菌（CoNS）鼻腔定植已被描述为随后发生全身感染的危险因素。在这项研究中，我们评估了定植于入住新生儿重症监护病房（NICU）的儿童鼻腔的 CoNS 分离株的遗传特征。
我们评估了 2007 年 7 月至 2008 年 5 月间巴西某主要城市 NICU 内新入院新生儿的 CoNS 定植情况。在入院和出院时，我们在甘露醇盐琼脂和胰蛋白酶大豆肉汤上筛选 CoNS 分离株，并使用纸片扩散法检测分离株对各种抗生素的敏感性。使用聚合酶链反应（PCR）来确定物种、mecA 基因的存在情况，并进行 SCCmec 分型。对从同一患儿入院和出院时分离的表皮葡萄球菌和溶血葡萄球菌进行 PFGE 特征分析。
在入住 NICU 的 429 名新生儿中，有 392 名（91.4%）在入院和出院时都采集了鼻腔拭子。住院期间 CoNS 的发生率为 55.9%（95%置信区间[CI]：50.9-60.7）。最常分离到的物种是溶血葡萄球菌（38.3%）和表皮葡萄球菌（38.0%）。入院时和出院时 CoNS 分离株的多重耐药（MDR）率分别为 2.2%和 29.9%（p=0.053）。mecA 基因在出院时分离株（83.6%）中比入院时分离株（60%）更常见；总体而言，SCCmec 类型 I 分离率最高。住院时间与 MDR 分离株定植相关（p<0.005）。表皮葡萄球菌和溶血葡萄球菌之间存在高度遗传多样性。
NICU 是 MDR CoNS 定植的高危环境。入住 NICU 的新生儿可能成为 CoNS 菌株的储存库，从而有可能将 MDR 菌株传播到社区。
