Multidrug-resistant Staphylococcus aureus strains have been commonly found in hospitals and communities causing wide ranges of infections among humans and animals. Typing of these strains is a key factor to reveal their clonal dissemination in different regions. We investigated the prevalence and dissemination of different clonal groups of S. aureus with resistance phenotype to multiple antibiotics in two sewage treatment plants (STPs) in Tehran, Iran over four sampling occasions. A total of 576 S. aureus were isolated from the inlet, sludge and outlet. Of these, 80 were identified as methicillin-resistant S. aureus (MRSA) and were further characterized using a combination of Phene Plate (PhP) typing, staphylococcal cassette chromosome mec (SCCmec), ccr types, prophage and antibiotic-resistant profiling. In all, eight common type (CT) and 13 single PhP type were identified in both STPs, with one major CT accounting for 38.8% of the MRSA strains. These strains belonged to three prophage patterns and five prophage types with SCCmec type III being the predominant type. Resistance to 11 out of the 17 antibiotics tested was significantly (P < 0.0059) higher among the MRSA isolates than methicillin-sensitive S. aureus (MSSA) strains. The persistence of the strains in samples collected from the outlet of both STPs was 31.9% for MRSA and 23.1% for MSSA. These data indicated that while the sewage treatment process, in general, is still useful for removing most MRSA populations, some strains with SCCmec type III may have a better ability to survive the STP process.

在医院和社区中普遍发现了耐多药性金黄色葡萄球菌菌株，在人和动物之间引起广泛的感染。这些菌株的分型是揭示它们在不同区域的克隆分布的关键因素。我们调查了伊朗德黑兰的两个污水处理厂（STP）在四个采样场合中对多种抗生素具有耐药表型的金黄色葡萄球菌不同克隆群的流行和分布。从进水口，污泥和出水口总共分离出576株金黄色葡萄球菌。其中80个被鉴定为耐甲氧西林的金黄色葡萄球菌（MRSA），并结合使用Phene Plate（PhP）分型，葡萄球菌盒式染色体mec（SCC mec），ccr类型，前噬菌体和抗生素耐药性分析来进一步表征。总共在两个STP中鉴定出8种普通型（CT）和13种单一PhP型，其中一种主要CT占MRSA菌株的38.8％。这些菌株属于三种传播方式和五种传播方式，其中以SCC mec III型为主。在MRSA分离物中，测试的17种抗生素中有11种的耐药性明显高于对甲氧西林敏感的金黄色葡萄球菌（P <0.0059）（MSSA）菌株。从两个STP出口收集的样品中菌株的持久性，MRSA为31.9％，MSSA为23.1％。这些数据表明，尽管污水处理过程通常仍可用于去除大多数MRSA种群，但某些SCC mec III型菌株可能具有更好的STP生存能力。