Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106, Oslo, Norway.
BMC Microbiol. 2020 Mar 4;20(1):46. doi: 10.1186/s12866-020-01730-w.
Quinolone resistant Escherichia coli (QREC) have been found in samples from Norwegian broiler chicken, despite quinolones not being administered to poultry in Norway. Biofilm production may be one factor contributing to the observed persistence in the broiler production chain. In the present study, 158 QREC strains from chicken caecal and retail meat samples were screened for biofilm production in microtiter plates, biofilm morphotype on Congo Red (CR) agar plates and phylotype by multiplex PCR. Furthermore, the dynamics in mixed biofilms with strains of different morphotypes were studied on glass slides and on CR agar plates.
All strains but one produced biofilm in microtiter plates and/or on CR agar plates at room temperature. There were no differences between strains from chicken caecum and chicken retail meat in the mean amount of biofilm produced in microtiter plates. Furthermore, no differences in biofilm production were observed between phylotypes. However, significant differences in biofilm production were found between biofilm morphotypes. The morphotype RDAR (red dry and rough, which has both curli and cellulose in the matrix, was displayed by 70% of the strains. Mean biofilm production by these strains were significantly higher than by strains with the morphotypes PDAR (pink dry and rough) with only cellulose or BDAR (brown dry and rough) with only curli. Interestingly, the two latter morphotypes produced biofilms with the morphotype RDAR when grown together. None of the strains achieved significantly higher numbers of colony forming units (cfu) in mixed biofilms than in single strain biofilms on glass slides.
The results indicate that QREC can form biofilm reservoirs on both inert and organic surfaces in production environments, as well as on meat. This may contribute to persistence and dissemination of the strains. Strains with both curli and cellulose in the biofilm matrix were significantly better biofilm formers than strains lacking one of these components. However, strains with only one of the components could compensate for this by producing mixed biofilms with strains having the other component, and thereby most likely enhance their probabilities of persistence in the production environment.
尽管挪威没有在禽类中使用喹诺酮类药物，但在挪威肉鸡的样本中发现了对喹诺酮类药物具有耐药性的大肠杆菌（QREC）。生物膜的产生可能是导致在肉鸡生产链中观察到持续存在的一个因素。在本研究中，从鸡盲肠和零售肉样本中筛选了 158 株 QREC 菌株，以在微量滴定板中检测生物膜的产生，在刚果红（CR）琼脂板上检测生物膜形态，并通过多重 PCR 检测菌株的基因型。此外，还在载玻片和 CR 琼脂板上研究了不同形态菌株混合生物膜的动态。
除一株菌外，所有菌株均可在微量滴定板和（或）室温下的 CR 琼脂板上产生生物膜。鸡盲肠和鸡肉零售肉样本中菌株在微量滴定板上产生的生物膜量之间没有差异。此外，生物膜产生与基因型之间也没有差异。然而，在生物膜形态之间观察到显著的生物膜产生差异。形态 RDAR（红色干燥粗糙，基质中既有卷曲菌又有纤维素）的菌株占 70%。这些菌株的平均生物膜产量明显高于形态 PDAR（粉色干燥粗糙）的菌株，后者仅含纤维素，或形态 BDAR（棕色干燥粗糙）的菌株，后者仅含卷曲菌。有趣的是，当这两种后一种形态的菌株一起生长时，它们可以产生形态 RDAR 的生物膜。与在载玻片上的单菌株生物膜相比，没有任何菌株在混合生物膜中形成的菌落形成单位（cfu）数量显著增加。
结果表明，QREC 可以在生产环境中的惰性和有机表面以及肉上形成生物膜库。这可能导致菌株的持续存在和传播。在生物膜基质中同时含有卷曲菌和纤维素的菌株明显比缺乏其中一种成分的菌株形成更好的生物膜。然而，只含有一种成分的菌株可以通过与另一种成分的菌株形成混合生物膜来弥补这一点，从而很可能增强它们在生产环境中持续存在的可能性。
