A unique strain of Escherichia coli O157:H7 that produces low verocytotoxin levels not detected by use of a commercial enzyme immunoassay kit

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Breath Formate Is a Marker of Airway S-Nitrosothiol Depletion in Severe Asthma

-nitrosothiols (SNOs), a class of endogenous airway smooth muscle relaxants. This deficiency results from increased activity of an enzyme that both reduces SNOs to ammonia and oxidizes formaldehyde to formic acid, a volatile carboxylic acid that is more easily detected in exhaled breath condensate (EBC) than SNOs. We therefore hypothesize that depletion of airway SNOs is related to asthma pathology, and breath formate concentration may be a proxy measure of SNO catabolism. (r = −0.39, p = 0.002, asthmatics only), and positively correlated with the NO-derived ion nitrite (r = 0.46, p<0.0001) as well as with total serum IgE (r = 0.28, p = 0.016, asthmatics only). Furthermore, formate was not significantly correlated with other volatile organic acids nor with inhaled corticosteroid dose.-nitrosothiols

MexEF-OprN Efflux Pump Exports the Pseudomonas Quinolone Signal (PQS) Precursor HHQ (4-hydroxy-2-heptylquinoline)

Bacterial cells have evolved the capacity to communicate between each other via small diffusible chemical signals termed autoinducers. Pseudomonas aeruginosa is an opportunistic pathogen involved, among others, in cystic fibrosis complications. Virulence of P. aeruginosa relies on its ability to produce a number of autoinducers, including 4-hydroxy-2-alkylquinolines (HAQ). In a cell density-dependent manner, accumulated signals induce the expression of multiple targets, especially virulence factors. This phenomenon, called quorum sensing, promotes bacterial capacity to cause disease. Furthermore, P. aeruginosa possesses many multidrug efflux pumps conferring adaptive resistance to antibiotics. Activity of some of these efflux pumps also influences quorum sensing. The present study demonstrates that the MexEF-OprN efflux pump modulates quorum sensing through secretion of a signalling molecule belonging to the HAQ family. Moreover, activation of MexEF-OprN reduces virulence factor expression and swarming motility. Since MexEF-OprN can be activated in infected hosts even in the absence of antibiotic selective pressure, it could promote establishment of chronic infections in the lungs of people suffering from cystic fibrosis, thus diminishing the immune response to virulence factors. Therapeutic drugs that affect multidrug efflux pumps and HAQ-mediated quorum sensing would be valuable tools to shut down bacterial virulence

Vibrio cholerae O139 susceptible to vibriostatic agent 0/129 and co-trimoxazole

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Target site modifications and efflux phenotype in clinical isolates of Streptococcus pneumoniae from Hong Kong with reduced susceptibility to fluoroquinolones

Ciprofloxacin-susceptible (n = 7) and -resistant (MIC ≥4 mg/L) (n = 15) clinical isolates of Streptococcus pneumoniae from diverse sources in Hong Kong were studied for target site modifications and efflux phenotype. Reserpine-inhibited efflux of ciprofloxacin and/or levofloxacin was common in both susceptible and non-susceptible isolates. The ParC substitutions K137N and/or S79F or Y were associated with increased ciprofloxacin MICs. The GyrA substitution S81F was only found in isolates with full resistance to ciprofloxacin (MIC ≥ 16 mg/L) and levofloxacin (MIC ≥ 8 mg/L). Among clinical isolates of S. pneumoniae, accumulation of target site mutations in strains with an efflux mechanism was associated with increasing MICs of fluoroquinolones.link_to_subscribed_fulltex

Application of a multiplex pbp2b and pbp2x PCR for prediction of penicillin resistance in Streptococcus pneumoniae [4]

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