Invasive group B streptococcal infections in adults, France (2007–2010)

AbstractGroup B streptococcus (GBS) has emerged as an important cause of invasive infection in adults. Here, we report the clinical and microbiological characteristics of 401 non-redundant GBS strains causing adult invasive infections collected during a 4-year period (2007–2010). Bacteraemia without focus (43.4%) and bone and joint infections (18.7%) were the main clinical manifestations. The distribution of capsular polysaccharide (CPS) type showed that types Ia, III, and V accounted for 71.8% of all strains. Resistance to erythromycin increased from 20.2% in 2007 to 35.3% in 2010, and was mainly associated with CPS type V harbouring the erm(B) resistant determinant

Diversity and Strain Specificity of Plant Cell Wall Degrading Enzymes Revealed by the Draft Genome of Ruminococcus flavefaciens FD-1

Peer reviewedPublisher PD

Comparative evaluation of VITEK 2 for antimicrobial susceptibility testing of group B Streptococcus

OBJECTIVES:Intrapartum antibiotic prophylaxis is recommended to prevent neonatal group B streptococcal (GBS) disease in colonized women, and penicillin or aminopenicillin constitute the first-line antibiotics. Most isolates are resistant to tetracycline, and resistance to macrolide-lincosamide-streptogramin (MLS) antibiotics is increasing. Therefore, laboratory testing for MLS resistance in GBS is now recommended for penicillin-allergic patients. The aim of this study was to compare the antimicrobial susceptibility of GBS as determined by the VITEK 2 system (bioMérieux, Marcy l'Etoile, France), agar diffusion methods and PCR-genotypic detection of resistance genes.METHODS:One hundred and ten unrelated selected GBS clinical isolates were studied. The antibiotics tested (VITEK 2 and agar diffusion method) were benzylpenicillin, ampicillin, erythromycin, clindamycin, co-trimoxazole, tetracycline, kanamycin, streptomycin and vancomycin. A standardized double-disc (DD) diffusion test was performed for MLS antibiotics. Genotypic characterization of tetracycline, MLS and aminoglycoside resistance genes was performed by PCR.RESULTS:All strains were susceptible to benzylpenicillin, ampicillin and vancomycin [category agreement (CA) between VITEK 2 and the diffusion method was 100%]. Ninety-five (86%) strains were resistant to tetracycline (CA was 98.9%). Eighty-one strains (73.6%) harboured an MLS resistance phenotype; 50 (61.8%) an MLS(B)-constitutive phenotype, 25 (30.8%) an MLS(B)-inducible phenotype and 6 (7.4%) an M phenotype. The agreement between data of VITEK 2 and the DD diffusion test for the detection of MLS(B)-constitutive, MLS(B)-inducible and M phenotype isolates was 76%, 36% and 100%, respectively. Almost all discrepancies were due to failure to detect erythromycin resistance by VITEK 2.CONCLUSIONS:VITEK 2 allows accurate determination of GBS susceptibility for the majority of antibiotics, but has to be improved for erythromycin. Thus, the DD diffusion test remains the most simple and reliable method for macrolide resistance detection among this streptococcal species

RNase activity prevents the growth of a fungal pathogen in tobacco leaves and increases upon induction of systemic acquired resistance with elicitin.

The hypersensitive response and systemic acquired resistance (SAR) can be induced in tobacco (Nicotiana tabacum L.) plants by cryptogein, an elicitin secreted by Phytophthora cryptogea. Stem application of cryptogein leads to the establishment of acquired resistance to subsequent leaf infection with Phytophthora parasitica var nicotianae, the agent of the tobacco black shank disease. We have studied early events that occur after the infection and show here that a tobacco gene encoding the extracellular S-like RNase NE is expressed in response to inoculation with the pathogenic fungus. Upon induction of SAR with cryptogein, the accumulation of NE transcripts coincided with a rapid induction of RNase activity and with the increase in the activity of at least two different extracellular RNases. Moreover, exogenous application of RNase activity in the extracellular space of leaves led to a reduction of the fungus development by up to 90%, independently of any cryptogein treatment and in the absence of apparent necrosis. These results indicate that the up-regulation of apoplastic RNase activity after inoculation could contribute to the control of fungal invasion in plants induced to SAR with cryptogein

RNase activity prevents the growth of a fungal pathogen in tobacco leaves and increases upon induction of systemic acquired resistance with elicitin.

International audienceThe hypersensitive response and systemic acquired resistance (SAR) can be induced in tobacco (Nicotiana tabacum L.) plants by cryptogein, an elicitin secreted by Phytophthora cryptogea. Stem application of cryptogein leads to the establishment of acquired resistance to subsequent leaf infection with Phytophthora parasitica var nicotianae, the agent of the tobacco black shank disease. We have studied early events that occur after the infection and show here that a tobacco gene encoding the extracellular S-like RNase NE is expressed in response to inoculation with the pathogenic fungus. Upon induction of SAR with cryptogein, the accumulation of NE transcripts coincided with a rapid induction of RNase activity and with the increase in the activity of at least two different extracellular RNases. Moreover, exogenous application of RNase activity in the extracellular space of leaves led to a reduction of the fungus development by up to 90%, independently of any cryptogein treatment and in the absence of apparent necrosis. These results indicate that the up-regulation of apoplastic RNase activity after inoculation could contribute to the control of fungal invasion in plants induced to SAR with cryptogein

Pathogen-induced elicitin production in transgenic tobacco generates a hypersensitive response and nonspecific disease resistance.

The rapid and effective activation of disease resistance responses is essential for plant defense against pathogen attack. These responses are initiated when pathogen-derived molecules (elicitors) are recognized by the host. We have developed a strategy for creating novel disease resistance traits whereby transgenic plants respond to infection by a virulent pathogen with the production of an elicitor. To this end, we generated transgenic tobacco plants harboring a fusion between the pathogen-inducible tobacco hsr 203J gene promoter and a Phytophthora cryptogea gene encoding the highly active elicitor cryptogein. Under noninduced conditions, the transgene was silent, and no cryptogein could be detected in the transgenic plants. In contrast, infection by the virulent fungus P. parasitica var nicotianae stimulated cryptogein production that coincided with the fast induction of several defense genes at and around the infection sites. Induced elicitor production resulted in a localized necrosis that resembled a P. cryptogea-induced hypersensitive response and that restricted further growth of the pathogen. The transgenic plants displayed enhanced resistance to fungal pathogens that were unrelated to Phytophthora species, such as Thielaviopsis basicola, Erysiphe cichoracearum, and Botrytis cinerea. Thus, broad-spectrum disease resistance of a plant can be generated without the constitutive synthesis of a transgene product

Potential impact of real-time processing and rapid susceptibility testing of blood samples in Gram-negative bloodstream infections in intensive care patients

International audienceIntroduction: Timely and appropriate therapy is critical in patients with Gram-negative bloodstream infections (GNBSI). Most bacteriology laboratories process blood specimen in the daytime, during laboratory operating hours, and use conventional culture for antimicrobial susceptibility testing (AST). We simulated the potential impact of real-time processing and rapid AST (7 hours) on early adaptation of the antibiotic regimen in intensive care unit (ICU) patients with GNBSI.Methods: All GNBSI episodes occurring in the ICUs of 2 hospitals in Paris were included. Data were collected. For each episode of bacteremia, we simulated the impact of three strategies: (1) Real-time processing coupled with conventional techniques (Gram stain and standard AST); (2) Standard processing coupled with rapid AST; and (3) Real-time processing coupled with rapid AST.Results: We included 109 episodes in 98 patients. Forty-two patients (48%) died during ICU stay. AST results led to a change of the antibiotic regimen in 66 (61%) episodes, mainly de-escalation (54/109, 55%). In standard care, median time from sample collection to definitive AST result was 65.9 hours (±26.7). The three strategies would have reduced time-to-result by 9.2 hours (±7.1), 30.8 hours (±19.7) and 40.0 hours (±20.6) respectively. Compared to standard care, strategies 1, 2 and 3 would have avoided 20, 69 and 90 patient-days of broad-spectrum antibiotics respectively.Conclusion: In addition to real-time processing of blood samples, rapid AST would be the most effective strategy to shorten time-to-result in critical patients with GNBSI