Champion E A, Miller M B, Popowitch E B, Hobbs M M, Saiman L, Muhlebach M S
Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina.
Pediatr Pulmonol. 2014 Mar;49(3):230-7. doi: 10.1002/ppul.22815. Epub 2013 Jun 14.
The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in cystic fibrosis (CF) patients in the United States is approximately 25%. Little is known about the relative proportion of hospital- versus community-associated strains or the antimicrobial susceptibility of MRSA in different CF centers. We hypothesized that the majority of MRSA isolates obtained from children with CF are those endemic in the hospital and that those associated with community acquisition (SCCmec IV) would be more resistant than typically seen in non-CF MRSA isolates.
We studied MRSA strains from seven pediatric CF centers to determine the clonal distribution based on DNA sequencing of the staphylococcal protein A gene (spa typing), the type of staphylococcal chromosomal cassette mec (SCCmec), and the proportion of strains with Panton-Valentine leukocidin (PVL). Antimicrobial susceptibility to systemic and topical antibiotics was compared between different MRSA types.
We analyzed 277 MRSA isolates from unique patients (mean age 11.15 ± 4.77 years, 55% male). Seventy % of isolates were SCCmec II PVL negative and the remainder SCCmec IV. Overall 17% MRSA strains were PVL positive (all SCCmec IV). Spa typing of 118 isolates showed most of the SCCmec II strains being t002, while SCCmec IV PVL positive isolates were t008, and SCCmec IV PVL negative isolates represented a variety of spa-types. The proportions of SCCmec II strains and spa-types were similar among centers. Overall rates of resistance to trimethoprim-sulfamethoxazole (4%), tetracycline (7%), tigecycline (0.4%), linezolid (0.4%) as well as fosfomycin (0.4%), fusidic acid (3%), and mupirocin (1%) were low. No strains were resistant to vancomycin. SCCmec II strains had higher rates of resistance to ciprofloxacin and clindamycin (P < 0.001) than SCCmec IV strains.
In this U.S. study, most MRSA isolates in the pediatric CF population were SCCmec II PVL negative. Rates of resistance were low, including to older and orally available antibiotics such as trimethoprim-sulfamethoxazole.
在美国，囊性纤维化（CF）患者中耐甲氧西林金黄色葡萄球菌（MRSA）的患病率约为25%。对于医院相关菌株与社区相关菌株的相对比例，或不同CF中心MRSA的抗菌药敏情况，人们了解甚少。我们推测，从CF患儿中分离出的大多数MRSA菌株是医院内流行的菌株，而那些与社区获得性感染相关的菌株（SCCmec IV型）比非CF MRSA分离株通常表现出更高的耐药性。
我们研究了来自7个儿科CF中心的MRSA菌株，通过对葡萄球菌蛋白A基因进行DNA测序（spa分型）、确定葡萄球菌染色体盒式mec（SCCmec）的类型以及携带杀白细胞素（PVL）的菌株比例，来确定克隆分布。比较了不同MRSA类型对全身和局部抗生素的药敏情况。
我们分析了来自不同患者的277株MRSA分离株（平均年龄11.15±4.77岁，55%为男性）。70%的分离株为SCCmec II型PVL阴性，其余为SCCmec IV型。总体而言，17%的MRSA菌株为PVL阳性（均为SCCmec IV型）。对118株分离株进行spa分型显示，大多数SCCmec II型菌株为t002型，而SCCmec IV型PVL阳性分离株为t008型，SCCmec IV型PVL阴性分离株则代表多种spa型。各中心之间SCCmec II型菌株和spa型的比例相似。对甲氧苄啶-磺胺甲恶唑（4%）、四环素（7%）、替加环素（0.4%）、利奈唑胺（0.4%）以及磷霉素（0.4%）、夫西地酸（3%）和莫匹罗星（1%）的总体耐药率较低。没有菌株对万古霉素耐药。SCCmec II型菌株对环丙沙星和克林霉素的耐药率高于SCCmec IV型菌株（P<0.001）。
在这项美国的研究中，儿科CF人群中的大多数MRSA分离株为SCCmec II型PVL阴性。耐药率较低，包括对较老的口服抗生素如甲氧苄啶-磺胺甲恶唑。
