Latorre-Fernández Javier, Aspiroz Carmen, Abdullahi Idris Nasir, Campaña-Burguet Allelen, Eguizábal Paula, González-Azcona Carmen, Tenorio Carmen, Zarazaga Myriam, Shittu Adebayo O, Lozano Carmen, Torres Carmen
Area of Biochemistry and Molecular Biology, OneHealth-UR Research Group, University of La Rioja, Logroño, Spain.
Laboratory of Clinical Microbiology, Hospital Universitario Royo Villanova, Zaragoza, Spain.
Microbiol Spectr. 2025 Jan 7;13(1):e0110224. doi: 10.1128/spectrum.01102-24. Epub 2024 Dec 10.
Livestock-associated methicillin-resistant (LA-MRSA), such as clonal-complex (CC)398, are of clinical relevance due to their multi-drug resistance profiles, adding to the overall burden of MRSA in humans. The objective was to evaluate the double-zone hemolysis (DZH) test as a simple and reliable method for detecting LA-MRSA in the clinical microbiology laboratory. isolates assigned to CC398 ( = 183; 152 MRSA/31 methicillin-susceptible [MSSA]), CC1 ( = 44; MRSA), and other CCs ( = 144; 94 MRSA/50 MSSA) were investigated. These isolates were screened for DZH on sheep blood agar plates after incubation at 37°C for 24 h. Identification of the (human adaptation marker) and genes (encoding hemolysin, intact or truncated) was performed by PCR. The positive and negative predictive values (PPV and NPV), sensitivity (SS), and specificity (SP) of the DZH test were determined. The DZH-positive phenotype was observed in 94.7%, 25%, and 6.4% of MRSA-CC398, MRSA-CC1, and MRSA of other lineages, respectively. Moreover, the DZH-positive phenotype was identified in 9.7% of MSSA-CC398 isolates but not in other MSSA lineages. All 164 DZH-positive isolates carried intact, and 99.4% was negative, suggesting an animal origin. Of the 207 DZH-negative isolates, 99.5% was positive (indicating human adaptation), and 95.2% possessed a truncated gene. The PPV/NPV/SS/SP values (in %) of the DZH test were as follows: detection of (i) LA-MRSA-CC398: (87.8/96.1/94.7/90.9); (ii) LA-MRSA-CC398/CC1 negative: (94.5/100/100/95.8); and (iii) negative: (99.4/99.5/99.4/99.5). The DZH is a reliable strategy to detect and distinguish LA-MRSA in the clinical microbiology laboratory and is recommended as an adjunct diagnostic test.
This study evaluated a simple and reliable phenotypic test that can be very useful in the clinical microbiology laboratory to detect livestock-associated (LA) methicillin-resistant (MRSA) isolates and of potential animal origin. The proposed double-zone hemolysis test has shown high positive and negative predictive values, sensitivity, and specificity to detect these LA-MRSA clones and of potential animal origin. Most LA-MRSA clones exhibit resistance to different classes of antibiotics, with unique epidemiological characteristics, and their early detection has public health relevance and patient management.
与家畜相关的耐甲氧西林金黄色葡萄球菌（LA-MRSA），如克隆复合体（CC）398，因其多重耐药性特征而具有临床相关性，增加了人类耐甲氧西林金黄色葡萄球菌的总体负担。目的是评估双区溶血（DZH）试验作为临床微生物实验室检测LA-MRSA的一种简单可靠的方法。对分配到CC398（n = 183；152株耐甲氧西林金黄色葡萄球菌/31株甲氧西林敏感金黄色葡萄球菌[MSSA]）、CC1（n = 44；耐甲氧西林金黄色葡萄球菌）和其他CCs（n = 144；94株耐甲氧西林金黄色葡萄球菌/50株甲氧西林敏感金黄色葡萄球菌）的分离株进行了研究。这些分离株在37°C孵育24小时后，在绵羊血琼脂平板上进行DZH筛选。通过聚合酶链反应对lukS（人类适应标志物）和hlb基因（编码溶血素，完整或截短）进行鉴定。确定了DZH试验的阳性和阴性预测值（PPV和NPV）、敏感性（SS）和特异性（SP）。在耐甲氧西林金黄色葡萄球菌-CC398、耐甲氧西林金黄色葡萄球菌-CC1和其他谱系的耐甲氧西林金黄色葡萄球菌中，分别有94.7%、25%和6.4%观察到DZH阳性表型。此外，在9.7%的MSSA-CC398分离株中鉴定出DZH阳性表型，但在其他MSSA谱系中未鉴定出。所有164株DZH阳性分离株均携带完整的hlb，99.4%的lukS为阴性，表明其源自动物。在207株DZH阴性分离株中，99.5%的lukS为阳性（表明人类适应），95.2%拥有截短的hlb基因。DZH试验的PPV/NPV/SS/SP值（以%计）如下：检测（i）LA-MRSA-CC398：（87.8/96.1/94.7/90.9）；（ii）LA-MRSA-CC398/CC1 lukS阴性：（94.5/100/100/95.8）；以及（iii）lukS阴性：（99.4/99.5/99.4/99.5）。DZH是临床微生物实验室检测和区分LA-MRSA的可靠策略，推荐作为辅助诊断试验。
本研究评估了一种简单可靠的表型试验，该试验在临床微生物实验室中对于检测与家畜相关的（LA）耐甲氧西林金黄色葡萄球菌（MRSA）分离株及潜在动物源的lukS非常有用。所提出的双区溶血试验在检测这些LA-MRSA克隆及潜在动物源的lukS方面显示出高阳性和阴性预测值、敏感性和特异性。大多数LA-MRSA克隆对不同类别的抗生素具有耐药性，具有独特的流行病学特征，其早期检测具有公共卫生相关性和患者管理意义。
