Athanasios Tsakris

Prof. Athanasios Tsakris

Department of Microbiology, Medical School University of Athens, Athens, Greece
orcid

Research Focus & Metrics

Academic Career Length

36Years (1991-Present)

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

Representative Publications

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31 March 2020 in PLOS ONE
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Cleo AnastassopoulouCleo Anastassopoulou
Cleo Anastassopoulou
LRLucia Russo
Lucia Russo
Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris
CSConstantinos Siettos
Constantinos Siettos
Since the first suspected case of coronavirus disease-2019 (COVID-19) on December 1st, 2019, in Wuhan, Hubei Province, China, a total of 40,235 confirmed cases and 909 deaths have been reported in China up to February 10, 2020, evoking fear locally and internationally. Here, based on the publicly available epidemiological data for Hubei, China from January 11 to February 10, 2020, we provide estimates of the main epidemiological parameters. In particular, we provide an estimation of the case fatality and case recovery ratios, along with their 90% confidence intervals as the outbreak evolves. On the basis of a Susceptible-Infectious-Recovered-Dead (SIDR) model, we provide estimations of the basic reproduction number (R0), and the per day infection mortality and recovery rates. By calibrating the parameters of the SIRD model to the reported data, we also attempt to forecast the evolution of the outbreak at the epicenter three weeks ahead, i.e. until February 29. As the number of infected individuals, especially of those with asymptomatic or mild courses, is suspected to be much higher than the official numbers, which can be considered only as a subset of the actual numbers of infected and recovered cases in the total population, we have repeated the calculations under a second scenario that considers twenty times the number of confirmed infected cases and forty times the number of recovered, leaving the number of deaths unchanged. Based on the reported data, the expected value of R0 as computed considering the period from the 11th of January until the 18th of January, using the official counts of confirmed cases was found to be ∼4.6, while the one computed under the second scenario was found to be ∼3.2. Thus, based on the SIRD simulations, the estimated average value of R0 was found to be ∼2.6 based on confirmed cases and ∼2 based on the second scenario. Our forecasting flashes a note of caution for the presently unfolding outbreak in China. Based on the official counts for confirmed cases, the simulations suggest that the cumulative number of infected could reach 180,000 (with a lower bound of 45,000) by February 29. Regarding the number of deaths, simulations forecast that on the basis of the up to the 10th of February reported data, the death toll might exceed 2,700 (as a lower bound) by February 29. Our analysis further reveals a significant decline of the case fatality ratio from January 26 to which various factors may have contributed, such as the severe control measures taken in Hubei, China (e.g. quarantine and hospitalization of infected individuals), but mainly because of the fact that the actual cumulative numbers of infected and recovered cases in the population most likely are much higher than the reported ones. Thus, in a scenario where we have taken twenty times the confirmed number of infected and forty times the confirmed number of recovered cases, the case fatality ratio is around ∼0.15% in the total population. Importantly, based on this scenario, simulations suggest a slow down of the outbreak in Hubei at the end of February.

1 January 2013 in International Journal of Antimicrobial Agents
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Journal Article
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Raffaele ZarrilliRaffaele Zarrilli
Raffaele Zarrilli
SPSpyros Pournaras
Spyros Pournaras
MGMaria Giannouli
Maria Giannouli
Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris

1 December 2011 in Clinical Microbiology and Infection
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OZO. Zarkotou
O. Zarkotou
SPS. Pournaras
S. Pournaras
PTP. Tselioti
P. Tselioti
VDV. Dragoumanos
V. Dragoumanos
VPV. Pitiriga
V. Pitiriga
Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris

1 February 2010 in Clinical Microbiology and Infection
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Journal Article
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VMVivi Miriagou
Vivi Miriagou
GCG. Cornaglia
G. Cornaglia
MEMikhail V. Edelstein
Mikhail V. Edelstein
Irene GalaniIrene Galani
Irene Galani
CGC.G. Giske
C.G. Giske
RCR. Cantón
R. Cantón
Acquired carbapenemases are emerging resistance determinants in Gram-negative pathogens, including Enterobacteriaceae, Pseudomonas aeruginosa and other Gram-negative non-fermenters. A consistent number of acquired carbapenemases have been identified during the past few years, belonging to either molecular class B (metallo-β-lactamases) or molecular classes A and D (serine carbapenemases), and genes encoding these enzymes are associated with mobile genetic elements that allow their rapid dissemination in the clinical setting. Therefore, detection and surveillance of carbapenemase-producing organisms have become matters of major importance for the selection of appropriate therapeutic schemes and the implementation of infection control measures. As carbapenemase production cannot be simply inferred from the resistance profile, criteria must be established for which isolates should be suspected and screened for carbapenemase production, and for which tests (phenotypic and/or genotypic) should be adopted for confirmation of the resistance mechanism. Moreover, strategies should be devised for surveillance of carbapenemase producers in order to enable the implementation of effective surveillance programmes. The above issues are addressed in this article, as a follow-up to an expert meeting on acquired carbapenemases that was recently organized by the ESCMID Study Group for Antibiotic Resistance Surveillance.

11 June 2010 in Journal of Antimicrobial Chemotherapy
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Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris
APAggeliki Poulou
Aggeliki Poulou
SPSpyros Pournaras
Spyros Pournaras
EVEvangelia Voulgari
Evangelia Voulgari
GVGeorgia Vrioni
Georgia Vrioni
DSDanai Sofianou
Danai Sofianou
The increasing frequency of class A KPC enzymes and class B metallo-β-lactamases (MBLs) among Enterobacteriaceae as well as their possible co-production makes their early differentiation urgent. A simple phenotypic algorithm employing three combined-disc tests consisting of meropenem alone and with phenylboronic acid (PBA), EDTA, or both PBA and EDTA was designed for the differentiation of KPC and MBL enzymes. Augmentation of the zone of inhibition by ≥5 mm was considered a positive combined-disc test result. A total of 141 genotypically confirmed carbapenemase-positive Enterobacteriaceae clinical isolates (63 KPC producers, 47 MBL producers, and 31 KPC and MBL producers) with various carbapenem MICs were examined. For comparison, 84 genotypically confirmed carbapenemase-negative Enterobacteriaceae clinical isolates [39 extended-spectrum β-lactamase (ESBL) producers, 22 AmpC producers, and 23 ESBL and AmpC producers] were also tested. The phenotypic algorithm was able to differentiate MBL from KPC producers as well as to detect the possible co-production of both carbapenemases (positive result only with the combined-disc test using meropenem alone and with both PBA and EDTA). The method detected all KPC or MBL producers (sensitivity 100%) as well as 30 of the KPC and MBL producers (sensitivity 96.8%). All three combined-disc tests were negative for non-carbapenemase-producing isolates, except two ESBL and AmpC producers that gave positive combined-disc tests using meropenem alone and with PBA and both PBA and EDTA (specificity for KPC detection 98.8%). This phenotypic method is very helpful to detect carbapenemase production and provides a simple algorithm for the differentiation of KPC and MBL enzymes, especially in regions where KPC- and MBL-possessing Enterobacteriaceae are highly prevalent.

7 February 2023 in Microorganisms
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MMMaria Mavrouli
Maria Mavrouli
SMSpyridon Mavroulis
Spyridon Mavroulis
ELEfthymios L. Lekkas
Efthymios L. Lekkas
Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris
Earthquakes are among the most impressive natural phenomena with very high potential to set off a chain of effects that significantly affects public health through casualties and injuries. Related disasters are attributed not only to the strong ground motion and coseismic phenomena but also to secondary effects, comprising mainly landslides and tsunamis, among others. All these can create harsh conditions favorable for the emergence of infectious diseases that are capable of causing additional human and economic losses and disruption of the emergency and recovery process. The present study comprises an extensive narrative review of the existing literature on the earthquake-triggered infectious diseases recorded worldwide, along with their symptoms, causative pathogens, associated risk factors, most vulnerable population groups, and prevention strategies. Respiratory, gastrointestinal, and vector-borne diseases, as well as wound and skin infections, are mainly recorded among the earthquake-affected population. Measures for effectively preventing earthquake-triggered infectious diseases are also proposed. One of the widely proposed measures is the establishment of a proper disease surveillance system in order to immediately and effectively identify the pre- and post-disaster occurrence of infectious diseases. This approach significantly contributes to disease trends monitoring, validation of early warning, and support of the emergency response and recovery actions.