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Appicciafuoco B.,Istituto Superiore di Sanita | Dragone R.,National Research Council Italy | Frazzoli C.,External Relations Office | Bolzoni G.,National Reference Center for Bovine Milk Quality | And 2 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2015

The use of antibiotics on lactating cows should be monitored for the possible risk of milk contamination with residues. Accordingly, Maximum Residue Levels (MRLs) are established by the European Commission to guarantee consumers safety. As pointed out by Dec 2002/657/EC, screening is the first step in the strategy for antibiotic residue control, thus playing a key role in the whole control procedure. However, current routine screening methods applied in milk chain still fail to detect residues of quinolones at concentrations of interest.This paper reports the findings of a new bio-optical method for the screening of quinolones residues in bovine milk, based on E. coli ATCC 11303 growth inhibition.The effect of blank and spiked cow milk samples (aliquots equivalents to 0.8%, v/v) is evaluated in Mueller Hinton Broth (MHb) and MHb enriched with MgSO4 2% (MHb-Mg) inoculated with the test strain at the concentration of 104CFU/mL.The presence of quinolones inhibits the cellular growth in MHb, while this effect is neutralized in MHb-Mg allowing both detection and presumptive identification of quinolones.Growth of the test strain is monitored at 37°C in a Bioscreen C automated system, and Optical Density (OD) at 600nm is recorded every 10min after shaking for 10s. Growth curves (OD vs. time) of E. coli ATCC 11303 are assessed in milk samples, with and without quinolones, and their differences in terms of δOD (δOD600nm=ODMHb-Mg-ODMHb) are calculated.The presence of quinolones is detected by the cellular growth inhibition (OD vs time, none increase in the value OD) and presumptively identified through the increase of the slope of δOD600nm curve (δOD vs. time), after about 3h of incubation.The detection limit for ciprofloxacin and enrofloxacin is at the level of MRL, for marbofloxacin is at 2-fold the MRL whereas for danofloxacin is at 4-fold the MRL. Although the sensitivity of the method could be further improved and the procedure automated, it is a promising step forward to integrate screening assays into the control process and, in particular, to fill in the gap for quinolones; moreover, these technological developments contribute to the One Health perspective through the monitoring of safe and correct use of veterinary antibiotics. © 2014 Elsevier B.V.

Bolzoni G.,National Reference Center for Bovine Milk Quality | Marcolini A.,National Reference Center for Bovine Milk Quality | Buffoli E.,National Reference Center for Bovine Milk Quality
Italian Journal of Food Science | Year: 2015

Derogations for somatic cell and total bacterial count limits had allowed non-compliant milk to be used for cheesemaking in Italy. Commercial and health considerations prompted a decision to implement a program to gradually repeal the derogations. In this study, we report the statistical evaluation of the situation in 2007-2008, the outcomes of the program to close the derogation and observations of its effects during its implementation from 2010-2013 in the Lombardy region. The introduction of a progressive decrease of the limit allowed regulators to minimize the negative impact on production levels by focusing on the management of the most non-compliant farms first.

Bolzoni G.,National Reference Center for Bovine Milk Quality | Marcolini A.,National Reference Center for Bovine Milk Quality
Milchwissenschaft | Year: 2010

The result of a 12 months project for a unified conversion line of Bactoscan FC (FOSS,DK) in Italy is reported. Participating laboratories (15) applied both, the reference method (ISO 4833:2003) and Bactoscan FC analysis on almost 100 cow's raw milk samples. After a first evaluation of the results of each laboratory for an individual conversion line, we chose a Linear Mixed Effects Model, for the statistical evaluation of 1474 "valid samples" (statistical selection of samples concerned repeatability of Bactoscan, dilution factor, maximum and minimum number of colonies on the plates). The regression line we obtained is: Log10 ( UFC/mL) = Log10 (IBC/uL) x 0.911 + 2,599 with (Sy/x) = 0.279. During 2010 some Italian laboratories will start to use the unified conversion line. With a progressive increase of the number of laboratories using the unified conversion line, we hope to improve (not to solve...) the problem of reproducibility of the instrumental method at a national level.

Bolzoni G.,National Reference Center for Bovine Milk Quality | Marcolini A.,National Reference Center for Bovine Milk Quality | Delle Donne G.,National Reference Center for Bovine Milk Quality | Appicciafuoco B.,National Reference Laboratory for Milk and Milk Products | Ferrini A.M.,National Reference Laboratory for Milk and Milk Products
Italian Journal of Food Science | Year: 2015

To improve the reproducibility of flow cytometry technique for total bacterial count in milk, a conversion from instrumental results (impulses/ìL) to the reference method resultes (cfu/mL) is needed. In 2008 in Italy, a project for a common conversion line for Bactoscan FC was initiated. In this paper we report on the second phase of the project focusing on the statistical procedure used to evaluate the validity of the data. The new conversion line, representative of national milk (2,732 valid samples from 29 labs) obtained from both rounds of the study is: Log10 (cfu mL-1) = Log10 (IBC μL-1) x 0.939 + 2.559, with Syx= 0.282 with an application range up to 70,000 IBC μL-1.

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