Detection and virulence potential of a phospholipase D-negative Corynebacterium ulcerans from a concurrent diphtheria and infectious mononucleosis case.

Diphtheria by Corynebacterium ulcerans is increasingly occurring in children, adolescents and adults. In addition to diphtheria toxin (DT), phospholipase D (PLD) is considered a virulence factor of C. ulcerans. In the present study, a first case of concurrent diphtheria by a PLD-negative C. ulcerans and infectious mononucleosis (IM) was verified. Clinical and microbiological profiles and binding properties to human Fibrinogen (Fbg), Fibronectin (Fn) and type I collagen (col I) biotinylated proteins and virulence to Caenorhabditis elegans were investigated for C. ulcerans strain 2590 (clinical isolate) and two control strains, including PLD-positive BR-AD22 wild type and PLD-negative ELHA-1 PLD mutant strains. MALDI-TOF assays and a multiplex PCR of genes coding for potentially toxigenic corynebacteria identified strain 2590 as non-DT producing. Interestingly, strain 2590 did not express PLD activity in the CAMP test although the presence of the pld gene was verified. PLD-negative 2590 and a PLD-positive 210932 strains showed similar affinity to Fbg, Fn and type I collagen. C. elegans were able to escape from C. ulcerans strains, independent of PLD and DT production. Higher mortality of nematodes was verified for PLD-negative strains. Additional studies concerning multifactorial virulence potential of C. ulcerans, including environmental conditions remain necessary.

Emergence of polymyxin B-resistant Acinetobacter baumannii in hospitals in Rio de Janeiro / Emergência de Acinetobacter baumannii resistente a polimixina B em hospitais do Rio de Janeiro

ABSTRACT Introduction: Acinetobacter baumannii has been considered a prevalent pathogen in hospitals, raising concern in the medical community due to its broad spectrum of antimicrobial resistance. Since it is a subject that arouses much interest, it has been increasingly studied. Due to the emergence of multidrug-resistant (MDR) Gram-negative bacteria, the use of polymyxins was reestablished. The polymyxins have been considered the only option for the treatment of severe infections caused by MDR A. baumannii. Objective: To investigate the susceptibility profile of A. baumannii to polymyxin B. Material and method: 92 clinical isolates from two public hospitals in the Rio de Janeiro city were studied using broth microdilution method. Results: Most of the isolates were resistant to polymyxin B, 81.5% (n = 75), and minimum inhibitory concentration (MIC) values ranged between 4-64 mcg/ml. Conclusion: These results are a concern since currently the polymyxins have been considered the most effective therapeutic option against MDR isolates of A. baumannii.

RESUMO Introdução: Acinetobacter baumannii tem sido considerado um patógeno prevalente nos hospitais, gerando preocupação na comunidade médica por conta de seu extenso espectro de resistência aos antimicrobianos. Por ser um assunto que desperta muito interesse, tem sido cada vez mais estudado. Devido à emergência de bactérias Gram-negativas resistentes a múltiplas drogas (MDR), o uso de polimixinas foi reestabelecido. As polimixinas têm sido consideradas a única opção para o tratamento de infecções graves causadas por A. baumannii MDR. Objetivo: Investigar o perfil de suscetibilidade de A. baumannii à polimixina B. Material e método: Foram estudados 92 isolados clínicos provenientes de dois hospitais da rede pública do município do Rio de Janeiro por meio da técnica de microdiluição em caldo. Resultados: A maioria dos isolados foi resistente à polimixina B, 81,5% (n = 75), apresentando valores de concentração inibitória mínima (CIM) entre 4-64 mcg/ml. Conclusão: Esses resultados são preocupantes, já que atualmente as polimixinas têm sido consideradas a opção terapêutica mais eficaz contra isolados de A. baumannii MDR.

The presence of qacA/B gene in Brazilian methicillin-resistant Staphylococcus aureus.

A total of 74 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from three government hospitals in 2002 and 2003 were examined concerning the distribution of qacA/B gene, which is the determinant of resistance to quaternary ammonium compounds largely employed in hospital disinfection. By polymerase chain reaction the qacA/B gene was found in 80% of the isolates, which is a significant result considering it is the first time that qacA/B gene is being reported for Brazilian MRSA strains and it is presented at a high rate.

The presence of qacA/B gene in Brazilian methicillin-resistant Staphylococcus aureus

A total of 74 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from three government hospitals in 2002 and 2003 were examined concerning the distribution of qacA/B gene, which is the determinant of resistance to quaternary ammonium compounds largely employed in hospital disinfection. By polymerase chain reaction the qacA/B gene was found in 80 percent of the isolates, which is a significant result considering it is the first time that qacA/B gene is being reported for Brazilian MRSA strains and it is presented at a high rate.

Glycosphingolipids from Magnaporthe grisea cells: expression of a ceramide dihexoside presenting phytosphingosine as the long-chain base.

Magnaporthe grisea is a fungal pathogen that infects rice leaves and causes rice blast, a devastating crop disease. M. grisea produces active elicitors of the hypersensitive response in rice that were previously identified as ceramide monohexosides (CMHs). Using several chromatographic approaches, mass spectrometry, and nuclear magnetic resonance, we identified ceramide mono- and dihexosides (CDH) in purified lipid extracts from M. grisea cells. As described by other authors, CMH consists of a ceramide moiety containing 9-methyl-4,8-sphingadienine in amidic linkage to 2-hydroxyoctadecenoic or 2-hydroxyhexadecenoic acids and a carbohydrate segment consisting of one residue of glucose. CDHs, however, contain beta-galactose (1-->4)-linked to beta-glucose as sugar units and phytosphingosine as the long-chain base, bound to a C24 alpha-hydroxylated fatty acid. To our knowledge, this is the first report on the occurrence of CDH in a fungal species and illustrates the existence of an alternative path of ceramide glycosylation in fungal cells.

Partial characterization of polysaccharides from Fusarium solani

A crude polysaccharide obtained from mycelium of Fusarium solani by treatment with 2 per center KOH/2h/100§C and fractionated by gel filtration chromatography yielded three fractions denoted L1,L2 and L3. Chemical analysis of the crude polysaccharide showed the presence od 89,5 per center total carbohydrate, 4 per center protin 14 per center uronic acid, traces of phosphate and hexosamine. Mannose, galactose, glucose and unidentifid pentose, were present in a 27.5:34:34.5:4 molar ratio.