Methicillin-Resistant Staphylococcus aureus Associated with Animals and Its Relevance to Human Health

Staphylococcus aureus is a typical human pathogen. Some animal S. aureus lineages have derived from human strains following profound genetic adaptation determining a change in host specificity. Due to the close relationship of animals with the environmental microbiome and resistome, animal staphylococcal strains also represent a source of resistance determinants. Methicillin-resistant S. aureus (MRSA) emerged 50 years ago as a nosocomial pathogen but in the last decade it has also become a frequent cause of infections in the community. The recent finding that MRSA frequently colonizes animals, especially livestock, has been a reason for concern, as it has revealed an expanded reservoir of MRSA. While MRSA strains recovered from companion animals are generally similar to human nosocomial MRSA, MRSA strains recovered from food animals appear to be specific animal-adapted clones. Since 2005, MRSA belonging to ST398 was recognized as a colonizer of pigs and human subjects professionally exposed to pig farming. The “pig” MRSA was also found to colonize other species of farmed animals, including horses, cattle, and poultry and was therefore designated livestock-associated (LA)-MRSA. LA-MRSA ST398 can cause infections in humans in contact with animals, and can infect hospitalized people, although at the moment this occurrence is relatively rare. Other animal-adapted MRSA clones have been detected in livestock, such as ST1 and ST9. Recently, ST130 MRSA isolated from bovine mastitis has been found to carry a novel mecA gene that eludes detection by conventional PCR tests. Similar ST130 strains have been isolated from human infections in UK, Denmark, and Germany at low frequency. It is plausible that the increased attention to animal MRSA will reveal other strains with peculiar characteristics that can pose a risk to human health

Preliminary slip rate estimates for the Düzce segment of the North Anatolian Fault Zone from offset geomorphic markers

New estimates on the Quaternary slip rate of the active transform margin of North Anatolia are provided. We investigated the area struck by the 12th November 1999, Mw 7.1 earthquake, that ruptured the Düzce fault segment of the North Anatolian Fault. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25,000-scale geological and geomorphological mapping along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and fluvial terraces inset into alluvial fan deposits. Radiocarbon dating indicates that ~100 m stream deflections were built up by the last ~7000 yrs of fault activity. Conversely, two documented and correlated Late Pleistocene fluvial terraces are horizontally offset by ~300 and ~900 m, respectively. These were dated by means of Optically Stimulated Luminescence (OSL) to ~21 ka BP and 60 ka BP. Assuming a constant rate of deformation for the Düzce Fault, ages and related offsets translate to consistent slip-rates that yield an average slip-rate of 15.0 ± 3.2 mm/yr for the last 60 ka. Thus, the Düzce Fault importantly contributes to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu fault to the south and confirming its important role in the seismic hazard of the area

Probabilistic approach to earthquake prediction.

The evaluation of any earthquake forecast hypothesis requires the application of rigorous statistical methods. It implies a univocal definition of the model characterising the concerned anomaly or precursor, so as it can be objectively recognised in any circumstance and by any observer.A valid forecast hypothesis is expected to maximise successes and minimise false alarms. The probability gain associated to a precursor is also a popular way to estimate the quality of the predictions based on such precursor. Some scientists make use of a statistical approach based on the computation of the likelihood of an observed realisation of seismic events, and on the comparison of the likelihood obtained under different hypotheses. This method can be extended to algorithms that allow the computation of the density distribution of the conditional probability of earthquake occurrence in space, time and magnitude. Whatever method is chosen for building up a new hypothesis, the final assessment of its validity should be carried out by a test on a new and independent set of observations. The implementation of this test could, however, be problematic for seismicity characterised by long-term recurrence intervals. Even using the historical record, that may span time windows extremely variable between a few centuries to a few millennia, we have a low probability to catch more than one or two events on the same fault. Extending the record of earthquakes of the past back in time up to several millennia, paleoseismology represents a great opportunity to study how earthquakes recur through time and thus provide innovative contributions to time-dependent seismic hazard assessment. Sets of paleoseimologically dated earthquakes have been established for some faults in the Mediterranean area: the Irpinia fault in Southern Italy, the Fucino fault in Central Italy, the El Asnam fault in Algeria and the Skinos fault in Central Greece. By using the age of the paleoearthquakes with their associated uncertainty we have computed, through a Montecarlo procedure, the probability that the observed inter-event times come from a uniform random distribution (null hypothesis). This probability is estimated approximately equal to 8.4% for the Irpinia fault, 0.5% for the Fucino fault, 49% for the El Asnam fault and 42% for the Skinos fault. So, the null Poisson hypothesis can be rejected with a confidence level of 99.5% for the Fucino fault, but it can be rejected only with a confidence level between 90% and 95% for the Irpinia fault, while it cannot be rejected for the other two cases. As discussed in the last section of this paper, whatever the scientific value of any prediction hypothesis, it should be considered effective only after evaluation of the balance between the costs and benefits introduced by its practical implementation

Geometry, kinematics and rates of deformation in a normal fault segment boundary, central Greece

The geometry, kinematics and rates of deformation within a fault segment boundary between the ends of two major active normal fault segments have been investigated through examination of a faulted 126 ka marine terrace. Slip‐vector azimuths defined by striations on the faults indicate N‐S extension on c. E‐W faults, sub‐parallel to those from earthquake focal mechanisms, together with significant and contemporaneous E‐W extension on c. N‐S faults. Summed rates of E‐W extension along a c. 550 m transect (0.17 mm/yr) are comparable with those for N‐S extension (0.20 mm/yr) along a c. 350 m transect. Our observations show that distributed non‐plane strain extension occurs in fault segment boundaries and this should be noted when studying fault‐tip fracture toughness and regional deformation rates

Slip rate of the Düzce segment of the North Anatolian Fault Zone from offset geomorphic markers

We provide new estimates on the Quaternary slip rate of the active transform margin of North Anatolia. We investigated the area struck by 12 November 1999, Mw 7.1 earthquake, that ruptured the Düzce fault segment. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25 000-scale geological and geomorphological map along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and remnant of an old alluvial fan modeled by fluvial terraces. The streams are deflected for a total of about 100 m and the onset of the offset was radiocarbon dated about 7000 yr BP. The two documented and correlated Late Pleistocene, terrace risers are offset of about 300 and 890 m, respectively. These terrace risers were dated by means of Optically Stimulated Luminescence (OSL) method about 21 000 yr BP and 60 000 yr BP. These ages and offsets translate to a constant rate of deformation of the Düzce Fault, at different time scales, of 14.0 ± 1.8 mm/yr and disproves a time-variable model at least for the last 60 000 yr. Considering the GPS-measured strain accumulation due to the plate motion along this part of the North Anatolian Fault Zone, the Düzce Fault importantly participates to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu fault to the south and assuming a relevant role in the seismic hazard of the area

Severe invasive methicillin-resistant S. aureus (USA300 clone) infection in an Italian adolescent

This report describes an uncommon presentation of invasive community-acquired methicillin-resistant S. aureus (CA-MRSA) infection in an immunocompetent adolescent without any other risk factor, characterized by septicaemia, meningitis, necrotising pneumonia and deep venous thrombosis (DVT). Successful treatment was performed with linezolid, rifampicin and low-molecular-weight heparin (LMWH). MRSA molecular typing revealed the presence of Panton-Valentine leukocidin (PVL) gene, and a genetic background identical to USA300 clone, an emerging aggressive CA-MRSA strain in USA and Europe

Combining inland and offshore paleotsunamis evidence: the Augusta Bay (eastern Sicily, Italy) case study

Offshore and inland geological evidence for multiple tsunami inundations was found in the Augusta Bay area: (1) the main local historical tsunamis (1908, 1693, 1169), (2) two far-generated tsunamis (i.e. Crete 365AD and Santorini, 3600 BP), and (3) seven unknown tsunamis). Average tsunami recurrence intervals from inland and offshore investigations of about 550 and 320 yr, respectively were obtained for the past 4 ka. The history of paleotsunamis from the marine record appears to be as complete as the historical one for the past millennium, yielding an average tsunami recurrence interval of 250 yr for the Augusta Bay. Geological data allow also estimating a minimum tsunami inundation distance of 530m and a minimum run-up of 5 m. The marine record contains evidence for more paleotsunamis with respect to the inland one because of continuous sedimentation and better preservation of stratigraphy in the offshore with respect to coastal areas, which are commonly affected by intermittent-erosion and sedimentation and anthropic activities. This work shows that the integration of geological and historical data can provide critical information regarding the extent and age of tsunamis of the past (e.g. inundation distance, age, and frequency), which is of immediate relevance for tsunami hazard assessment

Slip rate and earthquake recurrence of the Düzce fault (North Anatolian fault zone): integrating geomorphological and paleoseismological analyses

To learn about recurrence of large earthquakes and strain model on the Düzce segment of the North Anatolian Fault Zone, that ruptured on November, 12, 1999 (Mw 7.1), systematic geomorphological and paleoseismological analyses were integrated. In order to provide new estimates on Quaternary slip rate of the fault., geo-morphological mapping along the fault trace permitted to analyze fault-related cumulative landforms and drainage pattern settings. Remnant of an old alluvial fan modeled by fluvial terraces and 41 right-hand stream deflections were reconstructed, described and used as offset geomorphic markers. Two correlated Late Pleistocene, terrace risers, offset of about 300 and 900 m, respectively, were dated by means of OSL method about 21 kyr BP and 60 kyr BP. Moreover, the onset of the offset of the streams deflected for a total of 100 m was radiocarbon dated about 7000 yr BP. These data translate to a constant rate of deformation of 15.0±3.2 mm/yr for the last 60 kyr. On the basis of “characteristic-earthquake model” and under constant slip rate assumptions, it is possible to estimate that stream deflections across the Düzce Fault may be explained by repetition of 20-30 1999-like earthquakes during the last 7000 years, thus the recurrence time for surface rupturing events of the Düzce Fault is 290±60 years. With the aim to reconstruct the record of last large earthquakes, 10 trenches at five sites were excavated. By merging information obtained from all trenches, evidence for three surface faulting earthquakes prior to 1999 were found. These paleoearthquakes are dated on the basis of radiocarbon, 210Pb and archaeological information and can be summarized at: 1) AD1685-1900, possibly end of 19th century; 2) AD1685-1900, possibly close to AD1700; 3) AD800-1000. Some of them can be correlated to historical earthquakes occurred on AD967, 1719, 1878 or 1894. These paleoseismological results, merged with those from previous papers, are suggestive of bimodal recurrence distribution yielding overall average recurrence time of ~350 yrs for the past two millennia, compatible with that calculated from the geomorphic markers analysis. Under the assumption of “characteristic earthquake”, bimodal paleoearthquakes distribution indicate slip rate fluctuations during the past two millennia, with clustered high strain release. These results suggest Wallace-type strain release model for the Düzce fault, and average strain accumulation of 11.4±1.2 mm/yr, in agreement with slip rate results for the past 60 kyr obtained by geomorphic marker analysis