Ecological aspects and relationships of the emblematic Vachellia spp. exposed to anthropic pressures and parasitism in natural hyper-arid ecosystems: ethnobotanical elements, morphology, and biological nitrogen fixation.

MAIN CONCLUSION: Emblematic Vachellia spp. naturally exposed to hyper-arid conditions, intensive grazing, and parasitism maintain a high nitrogen content and functional mutualistic nitrogen-fixing symbioses. AlUla region in Saudi Arabia has a rich history regarding mankind, local wildlife, and fertility islands suitable for leguminous species, such as the emblematic Vachellia spp. desert trees. In this region, we investigated the characteristics of desert legumes in two nature reserves (Sharaan and Madakhil), at one archaeological site (Hegra), and in open public domains et al. Ward and Jabal Abu Oud. Biological nitrogen fixation (BNF), isotopes, and N and C contents were investigated through multiple lenses, including parasitism, plant tissues, species identification, plant maturity, health status, and plant growth. The average BNF rates of 19 Vachellia gerrardii and 21 Vachellia tortilis trees were respectively 39 and 67%, with low signs of inner N content fluctuations (2.10-2.63% N) compared to other co-occurring plants. The BNF of 23 R. raetam was just as high, with an average of 65% and steady inner N contents of 2.25 ± 0.30%. Regarding parasitism, infected Vachellia trees were unfazed compared to uninfected trees, thereby challenging the commonly accepted detrimental role of parasites. Overall, these results suggest that Vachellia trees and R. raetam shrubs exploit BNF in hyper-arid environments to maintain a high N content when exposed to parasitism and grazing. These findings underline the pivotal role of plant-bacteria mutualistic symbioses in desert environments. All ecological traits and relationships mentioned are further arguments in favor of these legumes serving as keystone species for ecological restoration and agro-silvo-pastoralism in the AlUla region.

Absence of Gigasporales and rarity of spores in a hot desert revealed by a multimethod approach.

Hot deserts impose extreme conditions on plants growing in arid soils. Deserts are expanding due to climate change, thereby increasing the vulnerability of ecosystems and the need to preserve them. Arbuscular mycorrhizal fungi (AMF) improve plant fitness by enhancing plant water/nutrient uptake and stress tolerance. However, few studies have focused on AMF diversity and community composition in deserts, and the soil and land use parameters affecting them. This study aimed to comprehensively describe AMF ecological features in a 5,000 km2 arid hyperalkaline region in AlUla, Saudi Arabia. We used a multimethod approach to analyse over 1,000 soil and 300 plant root samples of various species encompassing agricultural, old agricultural, urban and natural ecosystems. Our method involved metabarcoding using 18S and ITS2 markers, histological techniques for direct AMF colonization observation and soil spore extraction and observation. Our findings revealed a predominance of AMF taxa assigned to Glomeraceae, regardless of the local conditions, and an almost complete absence of Gigasporales taxa. Land use had little effect on the AMF richness, diversity and community composition, while soil texture, pH and substantial unexplained stochastic variance drove these compositions in AlUla soils. Mycorrhization was frequently observed in the studied plant species, even in usually non-mycorrhizal plant taxa (e.g. Amaranthaceae, Urticaceae). Date palms and Citrus trees, representing two major crops in the region, however, displayed a very low mycorrhizal frequency and intensity. AlUla soils had a very low concentration of spores, which were mostly small. This study generated new insight on AMF and specific behavioral features of these fungi in arid environments.

Ectomycorrhizal Communities Associated with the Legume Acacia spirorbis Growing on Contrasted Edaphic Constraints in New Caledonia.

This study aims to characterize the ectomycorrhizal (ECM) communities associated with Acacia spirorbis, a legume tree widely spread in New Caledonia that spontaneously grows on contrasted edaphic constraints, i.e. calcareous, ferralitic and volcano-sedimentary soils. Soil geochemical parameters and diversity of ECM communities were assessed in 12 sites representative of the three mains categories of soils. The ectomycorrhizal status of Acacia spirorbis was confirmed in all studied soils, with a fungal community dominated at 92% by Basidiomycota, mostly represented by/tomentella-thelephora (27.6%), /boletus (15.8%), /sebacina (10.5%), /russula-lactarius (10.5%) and /pisolithus-scleroderma (7.9%) lineages. The diversity and the proportion of the ECM lineages were similar for the ferralitic and volcano-sedimentary soils but significantly different for the calcareous soils. These differences in the distribution of the ECM communities were statistically correlated with pH, Ca, P and Al in the calcareous soils and with Co in the ferralitic soils. Altogether, these data suggest a high capacity of A. spirorbis to form ECM symbioses with a large spectrum of fungi regardless the soil categories with contrasted edaphic parameters.

Microplastics in the insular marine environment of the Southwest Indian Ocean carry a microbiome including antimicrobial resistant (AMR) bacteria: A case study from Reunion Island.

The increasing threats to ecosystems and humans from marine plastic pollution require a comprehensive assessment. We present a plastisphere case study from Reunion Island, a remote oceanic island located in the Southwest Indian Ocean, polluted by plastics. We characterized the plastic pollution on the island's coastal waters, described the associated microbiome, explored viable bacterial flora and the presence of antimicrobial resistant (AMR) bacteria. Reunion Island faces plastic pollution with up to 10,000 items/km2 in coastal water. These plastics host microbiomes dominated by Proteobacteria (80 %), including dominant genera such as Psychrobacter, Photobacterium, Pseudoalteromonas and Vibrio. Culturable microbiomes reach 107 CFU/g of microplastics, with dominance of Exiguobacterium and Pseudomonas. Plastics also carry AMR bacteria including ß-lactam resistance. Thus, Southwest Indian Ocean islands are facing serious plastic pollution. This pollution requires vigilant monitoring as it harbors a plastisphere including AMR, that threatens pristine ecosystems and potentially human health through the marine food chain.

A leguminous species exploiting alpha- and beta-rhizobia for adaptation to ultramafic and volcano-sedimentary soils: an endemic Acacia spirorbis model from New Caledonia.

Acacia spirorbis subsp. spirorbis Labill. is a widespread tree legume endemic to New Caledonia that grows in ultramafic (UF) and volcano-sedimentary (VS) soils. The aim of this study was to assess the symbiotic promiscuity of A. spirorbis with nodulating and nitrogen-fixing rhizobia in harsh edaphic conditions. Forty bacterial strains were isolated from root nodules and characterized through (i) multilocus sequence analyses, (ii) symbiotic efficiency and (iii) tolerance to metals. Notably, 32.5% of the rhizobia belonged to the Paraburkholderia genus and were only found in UF soils. The remaining 67.5%, isolated from both UF and VS soils, belonged to the Bradyrhizobium genus. Strains of the Paraburkholderia genus showed significantly higher nitrogen-fixing capacities than those of Bradyrhizobium genus. Strains of the two genera isolated from UF soils showed high metal tolerance and the respective genes occurred in 50% of strains. This is the first report of both alpha- and beta-rhizobia strains associated to an Acacia species adapted to UF and VS soils. Our findings suggest that A. spirorbis is an adaptive plant that establishes symbioses with whatever rhizobia is present in the soil, thus enabling the colonization of contrasted ecosystems.

Clinical Risk Factors for Infective Endocarditis in Staphylococcus aureus Bacteremia.

Crucial to the management of staphylococcal bacteremia is an accurate evaluation of associated endocarditis, which has both therapeutic and prognostic implications. Because the clinical presentation of endocarditis can be nonspecific, the judicious use of echocardiography is important in distinguishing patients at high risk of developing endocarditis. In the presence of high-risk clinical features, an early transesophageal echocardiogram is warranted without prior transthoracic echocardiography. The purpose of this study was to investigate the clinical risk factors for staphylococcal infective endocarditis that might warrant earlier transesophageal echocardiography and to describe the incidence of endocarditis in cases of methicillin-resistant and methicillin-sensitive Staphylococcus aureus bacteremia. A retrospective case-control study was conducted by means of chart review of 91 patients consecutively admitted to a community hospital from January 2009 through January 2013. Clinical risk factors of patients with staphylococcal bacteremia were compared with risk factors of patients who had definite diagnoses of infective endocarditis. There were 69 patients with bacteremia alone (76%) and 22 patients with endocarditis (24%), as verified by echocardiography. Univariate analysis showed that diabetes mellitus (P=0.024), the presence of an automatic implantable cardioverter-defibrillator/pacemaker (P=0.006) or a prosthetic heart valve (P=0.003), and recent hospitalization (P=0.048) were significantly associated with developing infective endocarditis in patients with S. aureus bacteremia. The incidence of methicillin-resistant and methicillin-sensitive S. aureus bacteremia was similar in the bacteremia and infective-endocarditis groups (P=0.437). In conclusion, identified high-risk clinical factors in the presence of bacteremia can suggest infective endocarditis. Early evaluation with transesophageal echocardiography might well be warranted.

Recurrent silent thyroiditis as a sequela of postpartum thyroiditis.

Thyroiditis encompasses a group of disorders characterized by thyroid inflammation. Though clinically indistinguishable from silent thyroiditis, postpartum thyroiditis occurs in women within 12 months after delivery. Recurrent postpartum thyroiditis in subsequent pregnancies is common, but recurrent silent thyroiditis is rare. We reported a case of patient with recurrent episodes of thyroiditis, unrelated to pregnancy, after an episode of postpartum thyroiditis. It is of interest that postpartum thyroiditis and silent thyroiditis could occur closely to each other; however, the link between these disorders is not well established. This report is to remind physicians of the possibility of recurrent silent thyroiditis in women with a history of postpartum thyroiditis.

Rheumatoid arthritis-associated corneal ulceration with superimposed infection by methicillin-resistant Staphylococcus aureus: a complicated type of corneal melt.

BACKGROUND: Severe extra-articular manifestations of rheumatoid arthritis usually occur in advanced stages of the disease. In particular, ocular involvement may lead to inflammatory corneal ulceration, in which therapy is challenging owing to its association with systemic vasculitis. Close collaboration between ophthalmologists and rheumatologists is paramount in providing the best treatment approach in this sight-threatening condition. CASE REPORT: We present a case of seropositive rheumatoid arthritis associated with corneal melting in the absence of other typical clinical manifestations of rheumatoid arthritis flare. The rheumatoid arthritis-associated corneal ulcer was complicated in our case by concomitant infection with methicillin-resistant Staphylococcus aureus, which was treated with intravenous vancomycin after an initial antimicrobial ophthalmic solution proved not to be making adequate improvement in the corneal healing. The recurrent corneal melting appeared to be aggravated by the ophthalmic infection while on immunosuppressive regimen. CONCLUSIONS: In patients on biologic agents, intravenous antibiotics must be considered in addition to ophthalmic eye solution in controlling the infectious process. Excluding concomitant ophthalmic infection is equally important before initiation of high-dose steroid and immunosuppressive regimens.

Finding the missing link in neuromyelitis optica presenting with recurrent transverse myelitis flares.

Neuromyelitis optica (NMO) is a distinct clinical entity from multiple sclerosis with its own clinical, laboratory and pathological characteristics. Definitive diagnosis of NMO is challenging at times as there can be a long interval between the occurrence of the index event and other neurological deficits which would fulfill the diagnostic criteria. Detection of NMO antibody could serve as an early marker in the disease progression. We present a young woman previously identified to have NMO antibody with recurring episodes of transverse myelitis for 3 years before manifesting with optic neuritis.

Atypical presentation of an advanced obstructive biliary cancer without jaundice.

PATIENT: Female, 60 FINAL DIAGNOSIS: Cholangiocarcinoma Symptoms: Abdominal pain • abdominal discomfort MEDICATION: - Clinical Procedure: - Specialty: Oncology. OBJECTIVE: Unusual natural history/clinical course. BACKGROUND: Cholangiocarcinoma remains to be a challenging case to diagnose and manage as it usually presents in advanced stage and survival rate remains dismal despite the medical breakthroughs. It is usually classified as intrahepatic, perihilar or distal tumor which can lead to bile duct obstruction causing sluggish flow of bile through the biliary tract and promoting increased absorption of bilirubin, bile acids and bile salts into systemic circulation accounting for the occurrence of jaundice, dark-colored urine and generalized pruritus. It usually becomes symptomatic when the tumor has significantly obstructed the biliary drainage causing painless jaundice and deranged liver function with cholestatic pattern. Jaundice occurs in 90% of the cases when the tumor has obstructed the biliary drainage system. A markedly dilated gallbladder as initial presenting feature in the absence of other typical obstructive clinical manifestations of an advanced stage of the cholangiocarcinoma is rare. CASE REPORT: This case report presents an atypical case of an elderly woman who presented with advanced metastatic ductal cholangiocarcinoma with markedly dilated gallbladder and liver mass without other clinical manifestations and laboratory evidence of cholestatic jaundice. CONCLUSIONS: The mere presence of Courvoisier's sign, even in the absence of other signs of biliary obstruction, could be suggestive of advanced neoplastic process along the biliary tract. Laboratory evidence of cholestasis might lag behind the clinical severity of the biliary obstruction in cholangiocarcinoma.

Microbiology and antibiotic susceptibility of organisms in bile cultures from patients with and without cholangitis at an Asian academic medical center.

PURPOSE: To review the epidemiology of microbial isolates from bile cultures taken from patients with and without cholangitis admitted to an Asian academic medical center in order to compare antimicrobial sensitivities and to make recommendations for empiric antimicrobial therapy of patients with cholangitis in the Philippines. METHODS: Routine aerobic bile culture results and corresponding clinical abstracts of surgical patients admitted to an academic medical center over a three-year period were analyzed. RESULTS: The series consisted of 125 patients, 77 with cholangitis (62%) and 48 (38%) without, which was determined according to the Tokyo Guidelines. Patients with cholangitis were significantly more likely to have positive bile cultures (p = 0.012). Gram-negative bacilli were the most common isolates in both patients with (94%) and patients without (95%) cholangitis. For both groups, Escherichia coli (36%) had greatest sensitivity to amikacin, cefepime, ceftriaxone, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam; Klebsiella pneumoniae (16%) had greatest sensitivity to amikacin, cefepime, ceftriaxone, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam; and Pseudomonas aeruginosa (12.5%) was most sensitive to cefepime, gentamicin, imipenem-cilastatin meropenem, and piperacillin-tazobactam. CONCLUSIONS: Gram-negative bacilli (or Enterobacteriaceae) (E. coli, K. pneumoniae, P. aeruginosa, and Enterobacter cloacae) were the most common aerobic microbial isolates in bile cultures from patients with cholangitis in the Philippines. Their antimicrobial susceptibility patterns suggest that imipenem-cilastatin (sensitivity 100%), meropenem (100%), amikacin (90-100%), cefepime (75%-100%), ceftriaxone (75%-100%), gentamicin (67%-100%), and piperacillin-tazobactam (50%-100%) would be the most effective antimicrobials for both groups. However, the authors echo the caution from the Surgical Infection Society/Infectious Diseases Society of America against using aminoglycosides as empiric drugs when safer and equally effective regimens are available.

Clinical and microbiological spectrum of necrotizing fasciitis in surgical patients at a Philippine university medical centre.

OBJECTIVE: The study describes the clinical characteristics, bacteriology and risk factors for mortality of patients with necrotizing fasciitis (NF), seen in a university medical centre. METHODS: The medical charts of NF patients admitted to the institution from January 2004 to July 2007 were retrieved and reviewed retrospectively. RESULTS: The majority of the 67 patients included in the study presented with localized nonspecific inflammatory manifestations: tenderness (94%), warmth (86%), oedema (76%), skin necrosis (75%), and ulceration (68%). Diabetes mellitus (22%) was the most common predisposing medical condition. The most frequent isolates were Escherichia coli (44%), Acinetobacter baumannii (19%), Staphylococcus aureus (15%) and Enterococcus faecium (15%). Overall mortality rate was 36%. Risk factors significantly associated with mortality were truncal involvement (p = 0.034), leukocytosis (p = 0.038), acidosis (p = 0.001), hypoalbuminaemia (p = 0.004), hypocalcaemia (p = 0.000) and hyponatraemia (p = 0.023). Logistic regression analysis revealed acidosis [p < 0.05, odds ratio (OR) = 9] and hypoalbuminaemia (p < 0.05, OR = 14) as significant independent risk factors for mortality. CONCLUSION: The identified risk factors can inform clinicians of increased mortality risks for certain patients with NF. They should serve as a trigger for more aggressive surgical and critical care, and antimicrobial therapy for these patients.