High Trophic Niche Overlap between a Native and Invasive Mink Does Not Drive Trophic Displacement of the Native Mink during an Invasion Process.

The pressure elicited by invasive species on native species significantly increases with the increase of the overlap of their ecological niches. Still, the specific mechanisms of the trophic displacement of native species during the invasion process are unclear. The effects of the invasive American mink (Neovison vison) on the critically endangered European mink (Mustela lutreola) was assessed by analyses of diet and niche overlap during the invasion process. To do this, the isotopic composition (δ13C and δ15N) of both species of mink and their four main types of prey was analysed. Significant trophic overlap between the native European mink and invasive American mink was found when they coexisted in sympatry. Furthermore, both mink species were characterised by significant individual variation in diet and no obvious change in diet of the native species in response to the arrival of the introduced species was observed. High niche overlap registered between both species in sympatry with no displacement in diet of the native mink in response to the arrival of the invasive mink is expected to have important consequences for the viability and conservation of the native mink populations, as it suggests high competitive pressure.

Isotopic niche partitioning in two sympatric howler monkey species.

OBJECTIVES: Ecological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning. MATERIALS AND METHODS: Between 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimate δ13 C and δ15 N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas. RESULTS: In allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by high δ15 N values, and included the majority of mantled howler monkeys' isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry. CONCLUSIONS: The coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.

Imbalance between endothelial damage and repair capacity in chronic obstructive pulmonary disease.

BACKGROUND: Circulating endothelial microparticles (EMPs) and progenitor cells (PCs) are biological markers of endothelial function and endogenous repair capacity. The study was aimed to investigate whether COPD patients have an imbalance between EMPs to PCs compared to controls and to evaluate the effect of cigarette smoke on these circulating markers. METHODS: Circulating EMPs and PCs were determined by flow cytometry in 27 nonsmokers, 20 smokers and 61 COPD patients with moderate to severe airflow obstruction. We compared total EMPs (CD31+CD42b-), apoptotic if they co-expressed Annexin-V+ or activated if they co-expressed CD62E+, circulating PCs (CD34+CD133+CD45+) and the EMPs/PCs ratio between groups. RESULTS: COPD patients presented increased levels of total and apoptotic circulating EMPs, and an increased EMPs/PCs ratio, compared with nonsmokers. Women had less circulating PCs than men through all groups and those with COPD showed lower levels of PCs than both control groups. In smokers, circulating EMPs and PCs did not differ from nonsmokers, being the EMPs/PCs ratio in an intermediate position between COPD and nonsmokers. CONCLUSIONS: We conclude that COPD patients present an imbalance between endothelial damage and repair capacity that might explain the frequent concurrence of cardiovascular disorders. Factors related to the disease itself and gender, rather than cigarette smoking, may account for this imbalance.

Analysis of the ectoenzymes ADA, ALP, ENPP1, and ENPP3, in the contents of ovarian endometriomas as candidate biomarkers of endometriosis.

PROBLEM: The diagnosis of endometriosis, a prevalent chronic disease with a strong inflammatory component, is usually delayed due to the lack of noninvasive diagnostic tests. Purinergic signaling, a key cell pathway, is altered in many inflammatory disorders. The aim of the present work was to evaluate the levels of adenosine deaminase (ADA), alkaline phosphatase (ALP), ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), and ENPP3, elements of purinergic signaling, as biomarker candidates for endometriosis. METHOD OF STUDY: A case-control comparative study was conducted to determine ADA, ALP, ENPP1 and ENPP3 levels in echo-guided aspirated fluids of endometriomas (case group) and simple ovarian cysts (control group) using the ELISA technique. RESULTS: Adenosine deaminase, ALP, ENPP1, and ENPP3 were present and quantifiable in the contents of endometriomas and simple cysts. There were significant differences in ADA and ENPP1 levels in endometriomas in comparison with simple cysts (2787 U/L and 103.9 ng/mL more in endometriomas, for ADA and ENPP1, respectively). Comparisons of ALP and ENPP3 levels between the two groups did not reveal significant differences. CONCLUSION: The ectoenzymes ADA and ENPP1 are biomarker candidates for endometriosis.

Factors Associated with Long-Term Sickness Absence Due to Mental Disorders: A Cohort Study of 7.112 Patients during the Spanish Economic Crisis.

BACKGROUND: Mental health problems are very common and often lead to prolonged sickness absence, having serious economic repercussions for most European countries. Periods of economic crisis are important social phenomena that are assumed to increase sickness absence due to mental disorders, although research on this topic remains scarce. The aim of this study was to gather data on long-term sickness absence (and relapse) due to mental disorders in Spain during a period of considerable socio-economic crisis. METHODS: Relationships were analyzed (using chi-squared tests and multivariate modelling via binary logistic regression) between clinical, social/employment-related and demographic factors associated and long-term sickness absence (>60 consecutive days) due to mental disorders in a cohort of 7112 Spanish patients during the period 2008-2012. RESULTS: Older age, severe mental disorders, being self-employed, having a non-permanent contract, and working in the real estate and construction sector were associated with an increased probability of long-term sickness absence (gender had a mediating role with respect to some of these variables). Relapses were associated with short-term sick leave (return to work due to 'improvement') and with working in the transport sector and public administration. CONCLUSIONS: Aside from medical factors, other social/employment-related and demographic factors have a significant influence on the duration of sickness absence due to mental disorders.

Influence of diet in the accumulation of organochlorine compounds in herons breeding in remote riverine environments.

The composition of organochlorine compounds (OCs), pentachlorobenzene (PeCB), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDTs and polychlorobiphenyls (PCBs), has been analyzed in eggs from cattle egret (Bubulcus ibis) and little egret (Egretta garzetta), two species of herons (family Ardeidae), nesting at the same remote riverine environment (Aiguabarreig, Ebro River). These two species were selected to evaluate the importance of diet in the accumulation of OCs. Cattle egret essentially feeds on dry grassy habitats and follow cattle or other large animals whereas little egret feeds on fish, amphibians and crustaceans captured in shallow waters. The δ(15)N and δ(13)C isotopic composition of the sampled eggs was studied and the results were consistent with these species feeding habits. In both species, the compounds accumulated the most were the less volatile and more lipophilic, e.g. PCB congeners of higher chlorination, DDT and metabolites. The distinct foraging species preferences were reflected in significant higher concentrations in little egret than cattle egret of all pollutant groups analysed. These differences were statistically significant for DDTs and PCBs (p < 0.015 and p < 0.047, respectively), e.g. the p,p'-DDE and PCB concentrations were 6 and 4.5 times higher, respectively, in the former than the latter. This strong contrast indicates that in remote environments aquatic riverine ecosystems are more efficient OC reservoirs than the terrestrial ecosystem.

Organochlorine compounds in Purple Heron eggs (Ardea purpurea) nesting in sites located around a chlor-alkali plant (Ebro River).

Eggs of Purple Heron (Ardea purpurea) were collected from three sampled sites inside the Ebro River basin in years 2006 and 2007. These sites were located besides (Flix), upstream (Aiguabarreig) and downstream (Delta) a chlor-alkali plant. Organochlorine compounds (OCs) such as dichlorodiphenyltrichloroethanes (DDTs), polychlorobiphenyls (PCBs), polychlorostyrenes (PCSs), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and hexachlorocyclohexanes (HCHs) were analysed to assess what are the accumulation patterns of these compounds in aquatic migratory birds breeding in the area of influence of the emissions from this industrial installation. Comparison of the egg concentrations between the three sites show higher concentrations of compounds manufactured in the past in the factory (PCBs, p,p'-DDT) or by-products of OC synthesis (HCB, PeCB and PCSs) in Flix than in Aiguabarreig reflecting a clear influence from the emissions of the chlor-alkali plant. The eggs collected in the Ebro Delta showed higher concentrations of total DDTs (mainly p,p'-DDE) than in the reference site (Aiguabarreig) which could reflect past applications of this insecticide in the area for agriculture. In contrast, HCHs were found in higher concentrations in the Delta and Aiguabarreig than in the Flix Reservoir. These compounds have been used as insecticides in agriculture and were not manufactured in the chlor-alkali plant. The present results show that despite Purple Herons are migratory birds, the food web transfer of OCs during the breeding season is sufficient for the accumulation of these compounds in the eggs, leading to statistically significant concentration differences between sites. These differences are consistent with the emissions of these pollutants from industrial or agricultural sources to the aquatic environments. Some of the p,p'-DDE concentrations observed in the area nearby the chlor-alkali plant are above the threshold effects for reproductive impairment.

Sex-specific foraging behavior in response to fishing activities in a threatened seabird.

Some seabird species have learnt to efficiently exploit fishing discards from trawling activities. However, a discard ban has been proposed as necessary in Europe to ensure the sustainability of the seas. It is of crucial importance for the management and conservation purposes to study the potential consequences of a discard ban on the foraging ecology of threatened seabirds. We assessed the influence of fishing activities on the feeding habits of 22 male and 15 female Audouin's gulls (Larus audouinii) from the Ebro Delta (Mediterranean Sea) during the breeding period using GPS loggers together with Stable Isotope Analysis (SIA), which provided new insights into their foraging behavior and trophic ecology, respectively. GPS data revealed different sex-specific foraging patterns between workdays and weekends. Females were highly consistent in that they foraged at sea throughout the week even though discarding stops at weekends. In contrast, males switched from foraging at sea during the week (when discards are produced) to an increased use of rice field habitats at weekends (when fishermen do not work). This sex-specific foraging behavior could be related to specific nutritional requirements associated with previous egg production, an energetically demanding period for females. However, on a broader time scale integrated by the SIA, both sexes showed a high degree of individual specialization in their trophic ecology. The need to obtain detailed information on the dependence and response of seabirds to fishing activities is crucial in conservation sciences. In this regard, sex-specific foraging behavior in relation to fisheries has been overlooked, despite the ecological and conservation implications. For instance, this situation may lead to sex differentiation in bycatch mortality in longlines when trawlers do not operate. Moreover, any new fisheries policy will need to be implemented gradually to facilitate the adaptation of a specialized species to a discard ban scenario.

Modelling terrestrial and marine foraging habitats in breeding Audouin's gulls Larus audouinii: timing matters.

Although the breeding ecology of Audouin's gull has been widely studied, its spatial distribution patterns have received little attention. We assessed the foraging movements of 36 GPS-tracked adult Audouin's gulls breeding at the Ebro Delta (NW Mediterranean), coinciding with the incubation period (May 2011). This also coincided with a trawling moratorium northwards from the colony. We modelled the distribution of the gulls by combining these tracking data with environmental variables (including fishing activities from Vessel Monitoring System, VMS), using Maxent. The modelling range included both marine and terrestrial areas. Models were produced separately for every 2h time interval across the day, and for 2 fishing activity scenarios (workdays vs. weekends), allowing to assess the spatio-temporal distribution patterns of the gulls and the degree of association with fisheries. During workdays, gull distribution at sea fully matched with fishing activities, both trawling (daylight) and purse-seining (nightime). Gulls tended to avoid the area under trawling moratorium, confirming the high influence of fisheries on the distribution patterns of this species. On weekends, gulls made lesser use of the sea and tended to increase the use of rice fields. Overall, Audouin's gull activity was more intense during dailight hours, although birds also showed nocturnal activity, on both workdays and weekends. Nocturnal patterns at sea were more disperse during the latter, probably because these gulls are able to capture small pelagic fish at night in natural conditions, but tend to congregate around purse-seiners (which would enhance their foraging efficiency) in workdays. These results provide important insight for the management of this species. This is of particular relevance under the current scenario of European fisheries policies, since new regulations are aimed at eliminating discards, and this would likely influence Audouin's gull populations.

Population control of an overabundant species achieved through consecutive anthropogenic perturbations.

The control of overabundant vertebrates is often problematic. Much work has focused on population-level responses and overabundance due to anthropogenic subsidies. However, far less work has been directed at investigating responses following the removal of subsidies. We investigate the consequences of two consecutive perturbations, the closure of a landfill and an inadvertent poisoning event, on the trophic ecology (δ13C, δ15N, and δ34S), survival, and population size of an overabundant generalist seabird species, the Yellow-legged Gull (Larus michahellis). We expected that the landfill closure would cause a strong dietary shift and the inadvertent poisoning a decrease in gull population size. As a long-lived species, we also anticipated adult survival to be buffered against the decrease in food availability but not against the inadvertent poisoning event. Stable isotope analysis confirmed the dietary shift towards marine resources after the disappearance of the landfill. Although the survival model was inconclusive, it did suggest that the perturbations had a negative effect on survival, which was followed by a recovery back to average values. Food limitation likely triggered dispersal to other populations, while poisoning may have increased mortality; these two processes were likely responsible for the large fall in population size that occurred after the two consecutive perturbations. Life-history theory suggests that perturbations may encourage species to halt existing breeding investment in order to ensure future survival. However, under strong perturbation pulses the resilience threshold might be surpassed and changes in population density can arise. Consecutive perturbations may effectively manage overabundant species.

From recruitment to senescence: food shapes the age-dependent pattern of breeding performance in a long-lived bird.

We used a long-term data set (26 years) from Audouin's Gull (Larus audouinii), a long-lived seabird, to address the relationship between the age-dependent pattern of reproductive performance and environmental conditions during breeding. Although theoretical models predict that the youngest and oldest breeders (due to inexperience and senescence, respectively) will perform less well than intermediate age classes, few empirical data exist regarding how this expected pattern varies with food availability. To assess the influence of age and food availability (corrected by population size of the main consumers to take into account density dependence) on a number of breeding parameters (laying dates, egg volume, clutch size, and hatching success), we modeled mean and variances of these parameters by incorporating heterogeneity into generalized linear models. All parameters varied with age and to different degrees, depending on food availability. As expected, performance improved with increased food supply, and the observed age pattern was quadratic, with poorer breeding performances occurring in extreme ages. For most parameters (except for laying dates, for which age and food did not interact), the pattern changed with food somewhat unexpectedly; the differences in performance between age classes were higher (i.e., the quadratic pattern was more noticeable) when food was more readily available than when food availability was lower. We suggest that, under poor environmental conditions, only high-quality individuals of the younger and older birds bred and that the differences in breeding performance between age classes were smaller. Although variances for egg volume were constant, variances for laying dates were highest for the youngest breeders and tended to decrease with age, either due to the selection of higher-quality individuals or to a greater frequency of birds skipping breeding with age, especially when food was in low supply. Our results show that mean and variances of breeding parameters changed with age, but that this pattern was different for each parameter and also varied according to food availability. It is likely that, other than food, certain additional factors (e.g., sex, cohort effects, density dependence) also influence changes in breeding performance with age, and this may preclude the finding of a common pattern among traits and among studies on different taxa.

Distinguishability and agreement with continuous data.

The analysis of concordance among repeated measures has received a huge amount of attention in the statistical literature leading to a range of different approaches. However, because all the approaches are able to assess the closeness among the readings taken on the same subject, the conclusions about the degree of concordance should be similar regardless the approach applied. Here, two indices to assess the concordance among continuous repeated measures, the intraclass correlation coefficient and the total deviation index, are applied and compared in two case examples. The first example concerns the repeatability of individual nutrient allocation strategy assessed by stable isotope analysis. The second example dealt with the assessment of the concordance of functional magnetic resonance imaging data that shows spatial correlation. The results differ depending upon the approach applied leading to contradictory conclusions about the degree of concordance. The reason behind these results is discussed reaching the conclusion that the total deviation index is just assessing agreement among repeated measurements, whereas the intraclass correlation coefficient assesses the concept of distinguishability among subjects that involves agreement among repeated measurements and spread of subjects at once. Therefore, the best way to select the right approach is to understand the right question behind the research hypothesis.

Ten years after the prestige oil spill: seabird trophic ecology as indicator of long-term effects on the coastal marine ecosystem.

Major oil spills can have long-term impacts since oil pollution does not only result in acute mortality of marine organisms, but also affects productivity levels, predator-prey dynamics, and damages habitats that support marine communities. However, despite the conservation implications of oil accidents, the monitoring and assessment of its lasting impacts still remains a difficult and daunting task. Here, we used European shags to evaluate the overall, lasting effects of the Prestige oil spill (2002) on the affected marine ecosystem. Using δ ¹5N and Hg analysis, we trace temporal changes in feeding ecology potentially related to alterations of the food web due to the spill. Using climatic and oceanic data, we also investigate the influence of North Atlantic Oscillation (NAO) index, the sea surface temperature (SST) and the chlorophyll a (Chl a) on the observed changes. Analysis of δ ¹5N and Hg concentrations revealed that after the Prestige oil spill, shag chicks abruptly switched their trophic level from a diet based on a high percentage of demersal-benthic fish to a higher proportion of pelagic/semi-pelagic species. There was no evidence that Chl a, SST and NAO reflected any particular changes or severity in environmental conditions for any year or season that may explain the sudden change observed in trophic level. Thus, this study highlighted an impact on the marine food web for at least three years. Our results provide the best evidence to date of the long-term consequences of the Prestige oil spill. They also show how, regardless of wider oceanographic variability, lasting impacts on predator-prey dynamics can be assessed using biochemical markers. This is particularly useful if larger scale and longer term monitoring of all trophic levels is unfeasible due to limited funding or high ecosystem complexity.

Anthropogenic input of heavy metals in two Audouin's gull breeding colonies.

Anthropogenic activities have become an important source of heavy metals to the marine environments. Biological sentinels like seabirds' chicks have been widely used to monitorize the levels of some heavy metals. Due to its mainly marine foraging habits, Audouin's gull fits well for this purpose. Mercury and lead levels were measured in mantle feathers of Audouin's gull chicks from two colonies in NE Iberian Peninsula: the Ebro Delta and the Llobregat Delta. Both are anthropized areas subject to differential pollutant inputs. Lead levels were significantly higher in the Llobregat Delta probably due to the use of leaded fuel in the nearby Barcelona airport. On the other side, mercury concentrations were higher in the Ebro Delta, in relation with the disposal of the toxic sediments at the Flix site carried down by the Ebro River. These mercury levels in the Ebro chicks reached values that have been described as toxic.

Trophic ecology of a resident Yellow-legged Gull (Larus michahellis) population in the Bay of Biscay.

Stable isotopes analyses (SIAs) are an efficient tool to obtain a general insight into the diet of generalist consumers, such as the Yellow-legged Gull (Larus michahellis). Here we analysed δ(13)C, δ(15)N and δ(34)S values in feathers of chicks and adults, and used Bayesian triple-isotope mixing models to reconstruct the diet of a Yellow-legged Gull population breeding in the southeastern Bay of Biscay. Questions to test were (1) whether adults and chicks rely on different feeding resources during breeding period; (2) whether there is a seasonal foraging effect involving a higher proportion of refuse food in winter compared to summer, and (3) the magnitude of the annual variation in diet. Prey consumption differed between colonies, among years, and also varied slightly between seasons, and this was mainly due to a differential use of prey of marine origin. However, diet did not differ between age classes. These results suggest a relatively monotonous diet with only slight variations from year to year, seasonally and at a local geographic scale.

Assessment of trace elements and stable isotopes of three Ardeid species at Birama Swamp, Cuba.

The Birama Swamp is the second largest wetland in the Caribbean region and it is inhabited by large populations of waterbirds. Here we report, for the first time, the foraging ecology and pollutant levels of three Ardeidae species: Cattle egret (Bubulcus ibis), Snowy egret (Egretta thula), and Tricolored heron (E. tricolor) breeding in this wetland using stable-isotope (δ (15)N and δ (13)C) and trace elements [mercury (Hg), lead (Pb), and selenium (Se)] analysis of chick feathers. Our results showed that individuals from all species occupied similar trophic levels. However, we found significant differences for δ (13)C, with the highest values in cattle egret indicating its use of terrestrial habitats and a generalist and opportunist behavior. No significant differences were found for Pb among species. Yet, Hg levels were greater and similar in tricolored heron and snowy egret than in cattle egret, which was associated with their greater use of aquatic environments. Snowy egret had the lowest values of Se differing significantly with the other two species suggesting a different relative use of prey type. Modeling log-Hg concentration in relation to δ (15)N and δ (13)C showed an independent and significant relationship among species but without interaction with species level indicating that within a particular species, higher Hg levels were associated with higher δ (15)N values. There was no interaction between δ (15)N and δ (13)C in the general linear models for Se and Pb in all species. We found an association between δ (15)N and species in Pb for snowy egret. The foraging habitat use of these species and the low levels of pollutants, which are lower than in other similar habitats in other areas of the world, indicated that there is not risk of negative effects in juvenile birds of the Birama Swamp colony that may impair their survival. Our results can be used as a baseline to achieve management regulations.

Trophodynamics of inorganic pollutants in a wide-range feeder: The relevance of dietary inputs and biomagnification in the Yellow-legged gull (Larus michahellis).

The suitability of sentinel species to monitor environmental pollution is often hampered by an insufficient knowledge on pollutant trophodynamics. We simultaneously evaluated the influence of individuals' trophic position (as revealed by δ(15)N values) and dietary exploitation of particular systems (using δ(13)C and δ(34)S as proxies) on inorganic pollutant concentrations measured on fledglings' feathers of a wide-range feeder, the Yellow-legged Gull (Larus michahellis), sampled at four locations throughout the Western Mediterranean. Concentrations of total Hg and Se in fledgling feathers (2.43 ± 1.30 and 1.16 ± 0.43 µg/g, respectively) were under the threshold points for deleterious effects on seabirds. On the contrary, alarming Pb concentrations were found in one colony (mean: 1.57 ± 2.46 µg/g, range: 0.16-12.13). With the exception of Pb, pollutant concentrations were positively influenced by consumption of marine resources (as suggested by the positive relationship with δ(34)S values), whereas trophic position played a minor role in determining pollutant body burdens.

A new approach to CD34+ hematopoietic progenitor cell counting.

BACKGROUND: In the absence of a gold standard for hematopoietic progenitor counting, the intra-laboratory variation between commonly used strategies for progenitor assessment was compared. METHODS AND MATERIALS: We used a pool of FITC-conjugated monoclonal antibodies (CD14, CD11b) and PE-CD34 to facilitate CD34 counting, excluding CD14(+)/CD11b(+) bright cells. We compared this protocol with other common methodologies, such as the single-staining approach, known as the Milan method, and the ISHAGE multiparameter method. RESULTS: We show that the CD14/CD11b protocol is a valid approach to progenitor cell counting. Though different methods give different results for progenitor cell counting, Lin's coefficient shows high concordance among flow cytometry counts but a substantial difference with colony- forming unit counts. Both the ISHAGE and CD14/CD11b protocol give higher counts than the Milan method. Moreover, on revising the ISHAGE analysis, we described a rare population of cells with the CD34(+)CD45(neg) phenotype, which could have an impact in CD34 counting. CONCLUSIONS: We have designed a valid alternative approach for hematopoietic progenitor cell counting, and we show that different methods give different results.

Comparison of antibiotic susceptibility of old and current Serratia.

AIMS: We explored changes in antibiotic susceptibility of Serratia marcescens in the last 50 years by comparing isolates collected between 1945 and 1950, and current isolates. MATERIALS & METHODS: Isolates were divided into three groups: environmental, clinical and 'old'. Susceptibility was determined by microdilution. Class 1 integrons were determined by PCR. Statistical analysis was conducted using the Kruskal-Wallis (K-W) tests with Bonferroni correction for multiplicity. Antimicrobials showing differences in the K-W test were analyzed by Mann-Whitney U test. Differences were considered significant when p < 0.05. RESULTS: All isolates were sensitive to ceftazidime, cefotaxime, kanamycin, gentamicin, ofloxacin and ciprofloxacin, and resistant to rifampicin, penicillin, ampicillin, amoxicillin, tetracycline, amoxicillin-clavulanic acid, cefazolin, cefamandole, polymyxin B/colistin, fusidic acid, lincosamides, streptogramins, daptomycin, linezolid and cefuroxime. Old isolates exhibited reduced susceptibility to streptomycin. Cefotaxime and streptomycin showed significant differences in the K-W test. None of the strains studied presented ESBL. Resistance to antimicrobials was not drastically different in Serratia when old and current strains were compared. CONCLUSION: Despite the multiple molecular mechanisms involved in bacterial resistance, withdrawing the antibiotics tends to restore the original phenotypes. Results from this report essentially confirm the conclusion obtained through metagenomic analysis that resistance to antibiotics already existed in ancient times.