Rafael Mateus Vargas

Dr. Rafael Mateus Vargas

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 November 2022 in Foods
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Journal Article
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BKBirsen Korkmaz
Birsen Korkmaz
DMDenny Maaz
Denny Maaz
FRFelix Reich
Felix Reich
CGCarl Gremse
Carl Gremse
AHAnnina Haase
Annina Haase
Julia Steinhoff-WagnerJulia Steinhoff-Wagner
Julia Steinhoff-Wagner
Environmental, hunting and handling factors affect the microbial load of hunted game and the resulting meat products. The aim of this study was to systematically investigate the influence of several factors on the initial microbial load (IML) of game carcasses during the early hunting chain. Eviscerated roe deer body cavities (n = 24) were investigated in terms of total viable count and the levels of Pseudomonas spp., Lactobacillus spp., Enterobacteriaceae and Escherichia coli (E. coli). Furthermore, a risk analysis based on the obtained original IML data, literature search and a Failure Mode and Effects Analysis (FMEA) was performed. The IML could be explained in a regression model by factors including the higher body weight (BW), damaged gastrointestinal tract by the shot, ambient temperature or rain. The levels of Lactobacillus spp. (p = 0.0472), Enterobacteriaceae (p = 0.0070) and E. coli (p = 0.0015) were lower on the belly flap surface when gloves were used during evisceration. The literature search revealed that studies examining influencing factors (IF) on the IML of game carcasses found contradictory effects of the comparable IF on IML. Potential handling failures may lead to a higher IML of game carcasses during the early hunting chain ranked by FMEA. Several handling practices for game carcasses are recommended, such as ensuring efficient cooling of heavier BW carcasses to limit bacterial growth or eviscerating heavier carcasses before lighter ones.

9 January 2022 in Antibiotics
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Journal Article
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FHFriederike Hahne
Friederike Hahne
SJSimon Jensch
Simon Jensch
GHGerd Hamscher
Gerd Hamscher
JMJessica Meißner
Jessica Meißner
MKManfred Kietzmann
Manfred Kietzmann
RVRafael Mateus Vargas
Rafael Mateus Vargas
Prudent use of antibiotics in livestock is widely considered to be important to prevent antibiotic resistance. This study aimed to evaluate the interactions between biofilms and veterinary antibiotics in therapeutic concentrations administrated via drinking water through a standardized experimental setup. In this context, two biofilms formed by pseudomonads (Pseudomonas (P.) aeruginosa or P. fluorescens) and a susceptible Escherichia (E.) coli strain were developed in a nutrient-poor medium on the inner surface of polyvinyl chloride pipe pieces. Subsequently, developing biofilms were exposed to sulfadiazine/trimethoprim (SDZ/TMP) or tylosin A (TYL A) in dosages recommended for application in drinking water for 5 or 7 days, respectively. Various interactions were detected between biofilms and antibiotics. Microbiological examinations revealed that only TYL A reduced the number of bacteria on the surface of the pipes. Additionally, susceptible E. coli survived both antibiotic treatments without observable changes in the minimum inhibitory concentration to 13 relevant antibiotics. Furthermore, as demonstrated by HPLC-UV, the dynamics of SDZ/TMP and TYL A in liquid media differed between the biofilms of both pseudomonads over the exposure period. We conclude that this approach represents an innovative step toward the effective evaluation of safe veterinary antibiotic use.

2 January 2022 in Agriculture
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RVRafael Mateus Vargas
Rafael Mateus Vargas
KBKira Butenholz
Kira Butenholz
Nina VolkmannNina Volkmann
Nina Volkmann
CSChristian Sürie
Christian Sürie
Nicole KemperNicole Kemper
Nicole Kemper
JSJochen Schulz
Jochen Schulz
Due to the relevance of cleaning and disinfection in farm hygiene management, accurate evaluation of the success of such procedures remains a fundamental challenge for producers. This study aimed to use boot swab sampling to quantify the effects of such practices in poultry barns. For this purpose, the counts of both the total and fecal indicator bacteria were detected after the application of a cleaning and disinfection protocol in identical barns that were occupied by turkeys and broilers. Boot swab samples were compared to an established agar contact plating method to evaluate disinfection success. Statistical analyses showed no correlations between the bacterial counts that were obtained with either method. In contrast to the agar contact plating method, boot swab sampling permitted the assessment of the hygienic conditions of the barn floors before and after cleaning procedures. Furthermore, according to observations with the boot swab method, factors related to the species being farmed influenced the initial bacterial loads but did not affect the effectiveness of cleaning and disinfection. Species identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) also suggested that non-fecal bacteria grow on selective media. Further studies should validate the use of this sampling technique by comparing different cleaning and disinfection protocols.

25 July 2019 in PLOS ONE
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Journal Article
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RVRafael Mateus Vargas
Rafael Mateus Vargas
Nicole KemperNicole Kemper
Nicole Kemper
NVNina Volkmann
Nina Volkmann
MKManfred Kietzmann
Manfred Kietzmann
JMJessica Meissner
Jessica Meissner
JSJochen Schulz
Jochen Schulz
Low-frequency electromagnetic fields (LF-EMF) may present an alternative to conventional sanitation methods of water supply lines in animal production. The objective of this study was to evaluate the effect of the application of LF-EMF on bacterial concentrations and biofilms at scale-models of different drinking systems (circulating and non-circulating) conventionally used in poultry holdings. Treated systems were equipped with commercial devices producing pulsed electromagnetic signals of low frequency up to 10,000 Hz; max. 21 mT. Exposure of water to LF-EMF resulted in changes of the culturable bacterial counts, although with high standard deviations. Differing between systems types, LF-EMF treatment seemed to be responsible either for a limitation or for an increase of colony forming unit counts, with partly statistically significant differences, especially in early stages of treatment. In contrast, neither biofilm formation nor counts of cells suspended in water differed between treated and control lines over 28 days of experiment, as determined by fluorescence microscopy. Although this study indicates that LF-EMF may influence culturability of water microorganisms, no clear inhibitory effects on bacterial biofilm formation or on planktonic microbes by LF-EMF treatment were confirmed in the experiments.

26 October 2022 in Microbiology Spectrum
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Journal Article
Open access
RVRafael Mateus Vargas
Rafael Mateus Vargas
TLTobias Lienen
Tobias Lienen
DMDenny Maaz
Denny Maaz
MRMartin Richter
Martin Richter
SMSven Maurischat
Sven Maurischat
Julia Steinhoff-WagnerJulia Steinhoff-Wagner
Julia Steinhoff-Wagner
Intensive research regarding the impact of land use-related factors on the prevalence and distribution of antimicrobial-resistantStaphylococcaceaein game ungulate populations is necessary for adequately determining risks related to interactions between wild animals, domestic animals, and humans in common geographic locations. This systematic approach for the analysis of the observations in specific hunting districts of Brandenburg, Germany, adds an innovative value to the research strategy of antimicrobial resistance in wild game animals, which is in accordance with current recommendations worldwide.

Verified
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JKJan Tobias Krüger
Jan Tobias Krüger
Kay-Peter HoyerKay-Peter Hoyer
Kay-Peter Hoyer
JHJingyuan Huang
Jingyuan Huang
VFViviane Filor
Viviane Filor
RVRafael Mateus Vargas
Rafael Mateus Vargas
MSMirko Schaper
Mirko Schaper
The development of bioresorbable materials for temporary implantation enables progress in medical technology. Iron (Fe)-based degradable materials are biocompatible and exhibit good mechanical properties, but their degradation rate is low. Aside from alloying with Manganese (Mn), the creation of phases with high electrochemical potential such as silver (Ag) phases to cause the anodic dissolution of FeMn is promising. However, to enable residue-free dissolution, the Ag needs to be modified. This concern is addressed, as FeMn modified with a degradable Ag-Calcium-Lanthanum (AgCaLa) alloy is investigated. The electrochemical properties and the degradation behavior are determined via a static immersion test. The local differences in electrochemical potential increase the degradation rate (low pH values), and the formation of gaps around the Ag phases (neutral pH values) demonstrates the benefit of the strategy. Nevertheless, the formation of corrosion-inhibiting layers avoids an increased degradation rate under a neutral pH value. The complete bioresorption of the material is possible since the phases of the degradable AgCaLa alloy dissolve after the FeMn matrix. Cell viability tests reveal biocompatibility, and the antibacterial activity of the degradation supernatant is observed. Thus, FeMn modified with degradable AgCaLa phases is promising as a bioresorbable material if corrosion-inhibiting layers can be diminished.