Detection of cfxA and cfxA2, the β-lactamase genes of Prevotella spp., in clinical samples from dentoalveolar infection by real-time PCR
Detection of cfxA and cfxA2, the β-lactamase genes of Prevotella spp., in clinical samples from dentoalveolar infection by real-time PCR
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DOI：
10.1128/jcm.44.1.172-176.2006
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发表时间：
2006-01-01
影响因子：
9.4
通讯作者：
Karasawa, T
中科院分区：
文献类型：
--
作者：
Iwahara, K;Kuriyama, T;Karasawa, T
虽然大多数与牙槽齿感染有关的细菌对青霉素高度敏感，但一些普雷沃氏菌菌株通过产生p -内酰胺酶对青霉素产生耐药性。普雷沃氏菌产生p -内酰胺酶反过来又与cfxA和cfxA2基因的表达有关。本研究的目的是利用实时荧光定量PCR （real-time PCR）测定cfx、4和cfxA2在普雷沃氏菌菌株中的流行率，并评估该分子方法在牙槽牙感染的87份临床样本（脓液和根管渗出液）中直接检测这些基因的性能。每个分离物的p -内酰胺酶产量用硝化甘油盘测定。在31%的普雷沃菌分离株中发现p -内酰胺酶产生，而其他所有菌株均为p -内酰胺酶阴性。分离株的青霉素耐药性与p -内酰胺酶的产生密切相关。每个反应混合物（5 × 10(3) CFU/ml）至少有5个细胞检测到cfxA和cfxA2基因。实时荧光定量PCR检测结果显示，48株p -内酰胺酶阳性普雷沃菌均存在cfxA和cfxA2。p -内酰胺酶阴性的普雷沃氏菌（n = 91）和非普雷沃氏菌（n = 31）均未检出上述基因。在本研究中，87份样品中有31份p -内酰胺酶阳性普雷沃氏菌，31份样品均检测到cfxA和cfxA2。在56份培养阴性样本中，8份（14%）通过实时PCR检测cfxA和cfxA2阳性。这种敏感和特异的分子方法提供了一种快速的临床试验，有助于选择适当的抗生素治疗牙槽牙感染。尽管青霉素在治疗牙槽感染方面仍然非常有效，但在涉及p -内酰胺酶阳性普氏菌菌株的情况下，应考虑使用p -内酰胺酶稳定的抗生素。
While most bacteria involved in dentoalveolar infection are highly susceptible to penicillin, some Prevotella strains exhibit resistance to this agent through the production of P-lactamase. The production of P-lactamase by Prevotella spp. is in turn associated with the expression of the genes cfxA and cfxA2. The aim of the present study was to determine the prevalence of cfx,4 and cfxA2 in Prevotella strains by use of real-time PCR and to assess the performance of this molecular method for the direct detection of the genes in 87 clinical samples (pus and root canal exudates) from dentoalveolar infection. Production of P-lactamase by each isolate was determined using a nitrocefin disk. P-Lactamase production was seen in 31% of Prevotella isolates, while all isolates of other species were P-lactamase negative. The penicillin resistance of isolates strongly correlated with the production of P-lactamase. Real-time PCR was found to detect the cfxA and cfxA2 genes from at least five cells per reaction mixture (5 X 10(3) CFU/ml of pus). Using real-time PCR, the presence of cfxA and cfxA2 was evident for all 48 P-lactamase-positive Prevotella strains. In contrast, neither P-lactamase-negative Prevotella (n = 91) or non-Prevotella (n = 31) strains were positive for the genes. In this study, 31 of the 87 samples yielded P-lactamase-positive Prevotella results, and cfxA and cfxA2 were detected in all 31 samples. Of the 56 culture-negative samples, 8 (14%) were positive for cfxA and cfxA2 by the real-time PCR. This sensitive and specific molecular method offers a rapid clinical test for aiding in the selection of an appropriate antibiotic for treatment of dentoalveolar infection. Although penicillin remains largely effective in the treatment of dentoalveolar infection, P-lactamase-stable antibiotics should be considered in cases in which P-lactamase-positive Prevotella strains are involved.