Characterization of Tetracycline-Resistant
            <i>Streptococcus thermophilus</i>
            Isolates from Italian Soft Cheeses

Rizzotti, Lucia; Gioia, Federica La; Dellaglio, Franco; Torriani, Sandra

doi:10.1128/aem.01380-08

Cited by 34 publications

(27 citation statements)

References 23 publications

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“…However, the lack of safety screening in locally maintained starters and adjunct cultures, as well as the occasional ART bacterial contamination from the environment and facility during cheese making, likely contributed to the sporadic cases of contaminated cheeses. This observation is also in agreement with the recent reports on dairy ART bacteria, but those bacteria were isolated mostly from specialty cheeses and from areas with probably less access to the cutting-edge literature and knowledge (2,16,17). However, there is no geographic boundary for the rapid dissemination of problematic organisms nowadays.…”

supporting

confidence: 81%

Effective Antibiotic Resistance Mitigation during Cheese Fermentation

Álvarez

et al. 2011

Appl Environ Microbiol

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Controlling antibiotic-resistant (ART) bacteria in cheese fermentation is important for food safety and public health. A plant-maintained culture was found to be a potential source for ART bacterial contamination in cheese fermentation. Antibiotics had a detectable effect on the ART population from contamination in the finished product. The decrease in the prevalence of antibiotic resistance (AR) in retail cheese samples from 2010 compared to data from 2006 suggested the effectiveness of targeted AR mitigation in related products.The rapid emergence of antibiotic-resistant (ART) pathogens has been a major public health concern (11). The recent findings on the prevalence of antibiotic resistance (AR) genecontaining ART commensal bacteria in a broad spectrum of ready-to-consume items (3,12,18,20) suggested that the food chain likely has served as an important avenue for dissemination of ART bacteria to the general public. From 2005 to 2006, small-scale surveillance studies using retail samples purchased from national chain grocery stores in the Columbus, OH, area revealed the presence of high levels of ART bacteria and a representative AR gene pool in most cheese samples (multiple types and brands) examined (14, 18). Various commensal bacteria, such as Streptococcus thermophilus, Pseudomonas sp., Staphylococcus sp., Lactococcus lactis, and Lactococcus sp., were identified to be the isolates carrying AR genes (18). The AR genes from certain food-borne isolates were further transmitted to human-pathogenic and residential bacteria in laboratory settings by horizontal gene transfer (HGT) mechanisms, leading to acquired resistance in the recipient cells, which suggests the functionality and mobility of the food-borne AR genes (5,12,18). The high prevalence of ART bacteria and the AR gene pool in cheese products and the identification of certain isolates carrying AR genes as lactic acid bacteria raised concerns about the potential impact of the dairy fermentation process on the emergence and amplification of ART bacteria. Thus, the objective of this study was to reveal critical control points (CCP) in reducing the number of ART bacteria in dairy fermentation for targeted mitigation.CCP assessment in pilot-plant-scale cheese making. Cheddar-type cheeses were made at the Ohio State University (OSU) pilot plant to determine the impact of starter cultures, the fermentation process, and antibiotics on the development of ART bacteria. The mesophilic culture F-DVS R-604 (culture A, containing a mix of L. lactis subsp. lactis and L. lactis subsp. cremoris) and the thermophilic culture F-DVS RSF-621 (culture B, containing L. lactis, Lactobacillus helveticus, and S. thermophilus), both from the Chr. Hansen Company (Milwaukee, WI), were used in the study. Cultures were activated by inoculating 2 to 3 g of a frozen pellet into 940 ml shelf-stable ultrahigh-temperature (UHT) milk (Parmalat 2% reduced-fat milk; Farmland Dairies, Wallington, NJ) and incubated at 33°C (mesophilic) or 38°C (thermophilic) for 18 h. Raw milk was obtained ...

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confidence: 81%

Effective Antibiotic Resistance Mitigation during Cheese Fermentation

Álvarez

et al. 2011

Appl Environ Microbiol

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“…Those microbiological breakpoints define a MICs which, if exceeded, triggers the need for a more extensive investigation to define the genetic basis of the observed resistance and to assess the risk for transfer of this resistance to other bacteria. In genotypic methods, the latest literature indicates that the search for acquired resistance genes using PCR-based techniques (Klare et al, 2007;Hummel et al, 2007;Ouoba et al, 2008;Ammor et al, 2008;Devirgiliis et al, 2008;Fukao et al, 2009;Rizzotti et al, 2009;Comunian et al, 2010) or micro-arrays (Ammor et al, 2008) is a powerful tool to identify resistant LAB strains. In case of suspected acquired resistance or intrinsic resistance, transferability tests are optional.…”

Section: Systematic Assessment Of Antibiotic Resistance In Probiotic mentioning

confidence: 99%

Assessment of Antibiotic Resistance in Probiotic Lactobacilli

Fukao¹,

Yajima²

2012

Antibiotic Resistant Bacteria - A Continuous Challenge in the New Millennium

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“…Eighty-three S. thermophilus strains, all (except two) dairy isolates, identified and genotypically differentiated in previous studies (16,24), were screened by consensus PCR with oligonucleotides HIS1-F and HIS1-R (9) made more stringent by changing the annealing temperature to 58°C for 40 s. They were subcultured in M17 broth (Oxoid, Milan, Italy) added with 0.5% (wt/vol) lactose (LM17) at 37°C for 24 h, and total genomic DNA was extracted and purified from 2-ml cultures as described by Rossi et al (26).…”

mentioning

confidence: 99%

Quantitative Analysis of Histidine Decarboxylase Gene (hdcA) Transcription and Histamine Production by Streptococcus thermophilus PRI60 under Conditions Relevant to Cheese Making

Rossi

Gardini

Rizzotti

et al. 2011

Appl Environ Microbiol

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This study evaluated the influence of parameters relevant for cheese making on histamine formation by Streptococcus thermophilus. Strains possessing a histidine decarboxylase (hdcA) gene represented 6% of the dairy isolates screened. The most histaminogenic, S. thermophilus PRI60, exhibited in skim milk a high basal level of expression of hdcA, upregulation in the presence of free histidine and salt, and repression after thermization. HdcA activity persisted in cell extracts, indicating that histamine might accumulate after cell lysis in cheese.

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Characterization of Tetracycline-Resistant Streptococcus thermophilus Isolates from Italian Soft Cheeses

Cited by 34 publications

References 23 publications

Effective Antibiotic Resistance Mitigation during Cheese Fermentation

Effective Antibiotic Resistance Mitigation during Cheese Fermentation

Assessment of Antibiotic Resistance in Probiotic Lactobacilli

Quantitative Analysis of Histidine Decarboxylase Gene (hdcA) Transcription and Histamine Production by Streptococcus thermophilus PRI60 under Conditions Relevant to Cheese Making

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