Reconciliation of the carbon budget in the ocean’s twilight zone

Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean1, 2. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage3. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude4, 5, 6, 7, 8. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink

Studio in vitro dell\u2019attivit\ue0 anti-fungina di un estratto di Spirulina platensis: un nuovo approccio per il trattamento delle candidosi muco-cutanee?

Introduzione L\u2019elevata incidenza di infezioni muco-cutanee da Candida spp., associata a emergenti fenomeni di resistenza e tossicit\ue0 ai farmaci azolici, ha portato alla necessit\ue0 di ricercare nuove strategie per la prevenzione e terapia di tali infezioni. In questo contesto, numerosi composti naturali sono stati testati per la loro potenziale attivit\ue0 anti-microbica ma solo pochi si sono rivelati sufficientemente efficaci e privi di effetti collaterali. Diverse specie di microalghe, come Spirulina platensis, sono note per la loro capacit\ue0 di produrre un\u2019ampia variet\ue0 di metaboliti con effetti antimicrobici e potrebbero essere utilizzate nella gestione di infezioni da microorganismi multi-resistenti. Scopo di questo studio \ue8 stata la valutazione in vitro dell\u2019attivit\ue0 anti-Candida di un estratto di Spirulina platensis. Metodi L\u2019estratto di Spirulina platensis \ue8 stato fornito da Alchemestry srl., Cesena. I ceppi di Candida spp. sono stati isolati su agar Sabouraud-destrosio da tamponi del cavo orale (N=8) e tamponi vaginali (N=18), pervenuti per esami di routine all\u2019U.O. di Microbiologia dell\u2019Ospedale Sant\u2019Orsola-Malpighi di Bologna. Per i 26 ceppi di Candida spp., appartenenti alle specie di pi\uf9 comune riscontro clinico, \ue8 stata determinata l\u2019attivit\ue0 anti-fungina della microalga tramite un saggio di micro-diluizione in brodo, allestito secondo le linee guida EUCAST (www.eucast.org). La minima concentrazione inibente (MIC) \ue8 stata definita come la pi\uf9 bassa concentrazione di estratto di Spirulina capace di inibire la crescita fungina di almeno il 50% rispetto al controllo privo di microalga. Inoltre, per determinare la minima concentrazione fungicida (MFC), sono stati seminati su agar Sabouraud-destrosio 50 \u3bcl di campione da ogni pozzetto che mostrava una significativa riduzione di crescita. La MFC \ue8 stata definita come la pi\uf9 bassa concentrazione di estratto di microalga capace di impedire totalmente la crescita o di ridurla a non pi\uf9 di 3 colonie fungine. Come controllo del metodo utilizzato, tutti i ceppi di Candida spp. sono stati testati con Amfotericina B e le MIC ottenute sono state confrontate con quelle attese secondo i dati EUCAST. Risultati L\u2019estratto di Spirulina platensis ha mostrato un buon effetto anti-fungino, con valori di MIC compresi fra 0.125 e 0.5 mg/ml. I ceppi di Candida glabrata, Candida parapsilosis e Candida guillermondii hanno evidenziato i valori di MIC pi\uf9 elevati. Per tutti i ceppi analizzati, inoltre, i valori di MFC erano sovrapponibili ai valori di MIC. Infine le MIC dell\u2019Amfotericina B hanno dimostrato di corrispondere ai dati EUCAST diponibili. Conclusioni Per il suo buon effetto anti-fungino, l\u2019estratto di Spirulina platensis potrebbe essere potenzialmente utilizzato in formulazioni topiche per la prevenzione/terapia di candidosi orali e vaginali. Ulteriori studi sono necessari per analizzare l\u2019esatta composizione chimica dell\u2019estratto di microalga e valutare i meccanismi che stanno alla base dell\u2019attivit\ue0 anti-Candida

Ease-of-use protocol for the rapid detection of third-generation cephalosporin resistance in Enterobacteriaceae isolated from blood cultures using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry

An ease-of-use protocol for the identification of resistance against third-generation cephalosporins in Enterobacteriaceae isolated from blood culture bottles was evaluated using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. A cefotaxime hydrolysis assay from chocolate agar subcultures using antibiotic discs and without inoculum standardization was developed for routine work flow, with minimal hands-on time. This assay showed good performance in distinguishing between cefotaxime-susceptible and cefotaxime-resistant strains, with excellent results for Escherichia coli (sensitivity 94.7%, specificity 100%). However, cefotaxime resistance was not detected reliably in Enterobacteriaceae expressing AmpC genes or carbapenemase-producing Klebsiella pneumonia

Use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to detect carbapenemase production in Enterobacteriaceae by a rapid meropenem degradation assay

We evaluated the analytical performance of a liquid chromatography-tandem mass spectrometry assay to detect carbapenemase activity in a group of carbapenemase-producing Enterobacteriaceae by meropenem hydrolysis. This one-hour method showed a sensitivity of 94% and a specificity of 100%, representing a rapid and reliable option compared to conventional phenotypic assay

Outbreak of Citrobacter freundii carrying VIM-1 in an Italian Hospital, identified during the carbapenemases screening actions, June 2012.

Objective: The identification of patients colonized or infected with carbapenemase-producing Enterobacteriaceae (CPE), in order to control and prevent the global spread of multidrug-resistant (MDR) pathogens. Methods: From June 1 to June 15, 2012, eight Citrobacter freundii strains with reduced susceptibility to carbapenems were isolated from rectal swabs of hospitalized patients during active screening following the detection of a Klebsiella pneumoniae carbapenemase (KPC) -positive patient on the ward. All isolates were analyzed phenotypically and molecularly by PCR and sequencing. Genotype clustering was performed by multilocus sequence typing (MLST) analysis. Results: The isolates showed high rates of multidrug resistance profile. A phenotypic assay for carbapenemase production suggested the presence of metallo-b-lactamase (MBL). The blaVIM-1 gene was detected in all imipenem-resistant C. freundii isolates. MLST showed that the C. freundii isolates shared the same sequence type (ST). Phylogenetic analysis revealed a strict relationship with an ST5 C. freundii isolate from a diarrhea patient in China. Conclusions: Our findings showed that the active surveillance program for CPE was useful, not only for the detection of KPC-producers, but also to identify and control the spread of other MDR pathogens that could expand the spectrum of circulating MDR pathogens