Zadik P M, Davies S, Whittaker S, Mason C
Public Health Laboratory, Herries Road, Sheffield S5 7BQ.
J Med Microbiol. 2001 May;50(5):476-479. doi: 10.1099/0022-1317-50-5-476.
The aims of this study were to evaluate the performance of a new medium, desferrioxamine oxacillin tellurite egg-yolk mannitol salt agar (DOTEMSA) in detecting methicillin-resistant Staphylococcus aureus (MRSA) and then to compare this medium against the Public Health Laboratory Service (PHLS) recommendation of mannitol salt agar (Oxoid) with oxacillin (OMSA) and Baird-Parker medium with ciprofloxacin (BPC) for the isolation of MRSA. The individual selective agents contained in DOTEMSA were tested against isolates of coagulase-negative staphylococci (CNS) and the medium with all constituents was challenged with various bacteria. Routine screening specimens were plated out on OMSA, BPC and DOTEMSA and the plates were incubated and examined at 24 and 48 h. Tellurite, desferrioxamine and oxacillin each inhibited the majority of CNS isolates; only three (of 103) grew in the presence of all three agents. Sixty-two of 63 isolates of MRSA grew on DOTEMSA and 59 produced lipase. Most other bacteria were inhibited. In all, 184 MRSA isolates were isolated from 540 screening specimens. The sensitivity of OMSA, BPC and DOTEMSA was 42%, 81% and 51% at 24 h, and 60%, 89% and 89% at 48 h. At 48 h, the combination of BPC and DOTEMSA detected 99% of MRSA isolates. Seventy, 49 and one non-MRSA isolates needed investigation for each of the three media respectively. A proposed strategy for MRSA screening would use BPC and DOTEMSA, examining BPC at 24 h and both media at 48 h. Provisional reports could then be issued at 24 h on the basis of rapid agglutination tests to confirm isolates as S. aureus from BPC and at 48 h on the basis of typical colonies from DOTEMSA.
本研究的目的是评估一种新型培养基——去铁胺苯唑西林亚碲酸盐蛋黄甘露醇盐琼脂（DOTEMSA）检测耐甲氧西林金黄色葡萄球菌（MRSA）的性能，然后将该培养基与公共卫生实验室服务处（PHLS）推荐的含苯唑西林的甘露醇盐琼脂（Oxoid）（OMSA）以及含环丙沙星的贝尔德-帕克培养基（BPC）用于分离MRSA的性能进行比较。对DOTEMSA中所含的各个选择性试剂针对凝固酶阴性葡萄球菌（CNS）分离株进行了测试，并将含有所有成分的培养基用各种细菌进行了挑战试验。将常规筛查标本接种于OMSA、BPC和DOTEMSA上，平板在24小时和48小时进行孵育和检查。亚碲酸盐、去铁胺和苯唑西林各自抑制了大多数CNS分离株；在所有三种试剂存在的情况下，103株中只有3株生长。63株MRSA分离株中有62株在DOTEMSA上生长，59株产生脂肪酶。大多数其他细菌受到抑制。总共从540份筛查标本中分离出184株MRSA分离株。OMSA、BPC和DOTEMSA在24小时时的敏感性分别为42%、81%和51%，在48小时时分别为60%、89%和89%。在48小时时，BPC和DOTEMSA联合检测出99%的MRSA分离株。三种培养基分别需要对70株、49株和l株非MRSA分离株进行进一步检测。一种提议的MRSA筛查策略将使用BPC和DOTEMSA，在24小时检查BPC，在48小时检查两种培养基。然后可以在24小时根据快速凝集试验发布初步报告，以确认从BPC分离出的菌株为金黄色葡萄球菌，并在48小时根据DOTEMSA上的典型菌落发布报告。
