Synergistic effects of Cinnamomum cassia L. essential oil in combination with polymyxin B against carbapenemase-producing Klebsiella pneumoniae and Serratia marcescens.

Multidrug resistance prompts the search for new sources of antibiotics with new targets at bacteria cell. To investigate the antibacterial activity of Cinnamomum cassia L. essential oil (CCeo) alone and in combination with antibiotics against carbapenemase-producing Klebsiella pneumoniae and Serratia marcescens. The antimicrobial susceptibility of the strains was determined by Vitek® 2 and confirmed by MALDI-TOF/TOF. The antibacterial activity of CCeo and its synergism with antibiotics was determined using agar disk diffusion, broth microdilution, time-kill, and checkboard methods. The integrity of the bacterial cell membrane in S. marcescens was monitored by protein leakage assay. CCeo exhibited inhibitory effects with MIC = 281.25 µg.mL-1. The association between CCeo and polymyxin B showed a decrease in terms of viable cell counts on survival curves over time after a 4 hour-treatment with a FIC index value of 0.006. Protein leakage was observed with increasing concentrations for CCeo and CCeo + polymyxin B treatments. CCeo showed antibacterial activity against the studied strains. When associated with polymyxin B, a synergistic effect was able to inhibit bacterial growth rapidly and consistently, making it a potential candidate for the development of an alternative treatment and drug delivery system for carbapenemase-producing strains.

Differential genomic damage in different tumor lines induced by prodigiosin.

Prodigiosin is a secondary metabolite produced by Serratia marcercens. As this pigment is suggested to be a cancer drug, genotoxicity studies are necessary. The aim of the present investigation was to evaluate the genotoxic effects of prodigiosin on tumoral and normal cell lines, NCIH-292, MCF-7 and HL-60. A normal line BGMK was used as control. Genomic damage induced by prodigiosin was observed in all tumor lines as well as the control line. The pigment induced the formation of micronuclei in tumor cells. The present data confirm the antitumor potential of prodigiosin. However, these findings also raise concerns regarding its target-specific action, as genotoxic effects on normal cells also occurred.

Outbreak of infection by extended-spectrum beta-lactamase SHV-5-producing Serratia marcescens in a Mexican hospital.

Previous outbreaks caused by Serratia marcescens have been associated with contaminated medical equipment, intravenous fluids and inadequate hygiene. We carried out the molecular characterization of an outbreak produced by a cephalosporin-resistant S. marscescens that occurred in a Mexican hospital in August 1999. The lethality of this outbreak was 26%. Positive isolates were collected from 20 patients, one medical staff and three chlorhexidine disinfectant solutions. Results of PFGE, beta-lactamase patterns, sequencing of PCR amplifications, plasmid profiles, and mating experiments showed that the outbreak occurred by the dissemination of a S. marcescens SHV-5 producing strain. The adequate enforcement of procedures under the supervision of an infection control resulted in the abrupt end of the outbreak.

[An epidemic of primary bacteremia due to an endemic strain of Serratia marcescens in an intensive care unit]. / Epidemia de bacteremias primarias por una cepa endémica de Serratia marcescens en una unidad de terapia intensiva.

An outbreak of Serratia marcescens bacteremia detected in the intensive care unit (ICU) of a tertiary care center on the last days of October, 1985, is described. The rate of primary S. marcescens nosocomial bacteremia during the pre-epidemic period (January-September 1985) was 6.25 per cent; and for the post-epidemic period compared with the epidemic were significantly different (p < 0.0001). The outbreak strains belonged to the biotype A8b, which has been endemic in our hospital. The responsible organism exhibited an unusual antimicrobial resistance pattern associated to the presence of a specific plasmid (greater than 50 kilobases), which showed similar fragments after restriction endonuclease digestion. No specific risk factors were identified in the case-control study. The outbreak was probably related to a greater influx of infected patients, resulting in less careful infection control measures, due to the emergency situation which suffered the hospital after the earthquakes in 1985. The unusual high rate of blood isolation of S. marcescens at the ICU was the first sign of the outbreak. The prompt reinforcement of infection control policies facilitated its resolution.