Antibiotic resistance patterns of bacterial strains isolated from Periplaneta americana and Musca domestica in Tangier, Morocco

Background: Flies and cockroaches are two insects in close contact with human beings. They are carriers of human pathogenic bacteria on the external areas of their bodies or in their digestive tracts. This study examines Periplaneta americana and Musca domestica collected from the residential areas of six districts in Tangier, Morocco. Methodology: In total, 251 bacteria were isolated from external areas of the participants' bodies and the antimicrobial susceptibility was calculated. Results: The predominant bacterial species included Escherichia coli (17.9%), Klebsiella spp. (14.7%), Providencia spp. (9.6%), Staphylococcus spp. (15.1%) and Enterococcus spp. (11.6%). The study showed no difference between the species of bacterial strains from American cockroaches and houseflies. Carbapenems and aminoglycosides were active against 100% of the Gram-negative bacilli isolated in this study. Staphylococcus spp. strains were susceptible to linezolid, vancomycin, daptomycin, levofloxacin and cotrimoxazole, and no antibiotic resistance was found in Enterococcus spp. Conclusions: In our setting, although both cockroaches and flies collected from residential areas may be vectors of human pathogenic bacteria, the infections caused by them are easily treatable as a result of the high susceptibility of their bacteria to antibiotics routinely used in the community or in hospitals

Aeromonas Surface Glucan Attached through the O-Antigen Ligase Represents a New Way to Obtain UDP-Glucose

We previously reported that A. hydrophila GalU mutants were still able to produce UDP-glucose introduced as a glucose residue in their lipopolysaccharide core. In this study, we found the unique origin of this UDP-glucose from a branched α-glucan surface polysaccharide. This glucan, surface attached through the O-antigen ligase (WaaL), is common to the mesophilic Aeromonas strains tested. The Aeromonas glucan is produced by the action of the glycogen synthase (GlgA) and the UDP-Glc pyrophosphorylase (GlgC), the latter wrongly indicated as an ADP-Glc pyrophosphorylase in the Aeromonas genomes available. The Aeromonas glycogen synthase is able to react with UDP or ADP-glucose, which is not the case of E. coli glycogen synthase only reacting with ADP-glucose. The Aeromonas surface glucan has a role enhancing biofilm formation. Finally, for the first time to our knowledge, a clear preference on behalf of bacterial survival and pathogenesis is observed when choosing to produce one or other surface saccharide molecules to produce (lipopolysaccharide core or glucan)

Aeromonas surface glucan attached throught the O-antigen ligase represents a new way to obtain UDP-Glucose

We previously reported that A. hydrophila GalU mutants were still able to produce UDP-glucose introduced as a glucose residue in their lipopolysaccharide core. In this study, we found the unique origin of this UDP-glucose from a branched α-glucan surface polysaccharide. This glucan, surface attached through the O-antigen ligase (WaaL), is common to the mesophilic Aeromonas strains tested. The Aeromonas glucan is produced by the action of the glycogen synthase (GlgA) and the UDP-Glc pyrophosphorylase (GlgC), the latter wrongly indicated as an ADP-Glc pyrophosphorylase in the Aeromonas genomes available. The Aeromonas glycogen synthase is able to react with UDP or ADP-glucose, which is not the case of E. coli glycogen synthase only reacting with ADP-glucose. The Aeromonas surface glucan has a role enhancing biofilm formation. Finally, for the first time to our knowledge, a clear preference on behalf of bacterial survival and pathogenesis is observed when choosing to produce one or other surface saccharide molecules to produce (lipopolysaccharide core or glucan)

LPS of <i>Aeromonas hydrophila</i> AH-3.

<p>(A) Chemical structure of the LPS-core of <i>A. hydrophila</i> strain AH-3 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035707#pone.0035707-KnirelYA2" target="_blank">[36]</a>. The O34-antigen is linked to the Gal residue (shown in italics) of the LPS core <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035707#pone.0035707-KnirelYA2" target="_blank">[36]</a>. (B) Silver-stained SDS-PAGE of purified LPS from <i>A. hydrophila</i> strain AH-3 (lane 1) and GalU mutant AH-2886 (lane 2) and structures of the two LPS-core bands of AH-2886 mutant <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035707#pone.0035707-Vilches1" target="_blank">[3]</a>. All monosaccharides are in the pyranose form. Kdo, 3-deoxy-d-<i>manno</i>-oct-2-ulosonic acid; l-α-d-Hep, d-α-d-Hep, l-<i>glycero</i>- and d-<i>glycero</i>-α-d-<i>manno</i>-heptose; Glc, glucose; GlcN, glucosamine; Gal, galactose. C = LPS core, O = O34-antigen LPS.</p

Sephadex G-50 gel permeation chromatography elution profiles of the water soluble (carbohydrate) material isolated by mild acid degradation of the LPS preparations from <i>A. hydrophyla</i> AH-3 (wild type) (A), AH-3Δ<i>rmlB</i> (B), AH-3Δ<i>wecP</i> (C) and AH-3Δ<i>glgA</i> (D) mutants.

<p>Sephadex G-50 gel permeation chromatography elution profiles of the water soluble (carbohydrate) material isolated by mild acid degradation of the LPS preparations from <i>A. hydrophyla</i> AH-3 (wild type) (A), AH-3Δ<i>rmlB</i> (B), AH-3Δ<i>wecP</i> (C) and AH-3Δ<i>glgA</i> (D) mutants.</p

Negative ions ESI-MS of the core oligosaccharide LPS.

<p>(A) Core oligosaccharide obtained by acid release from the purified LPS of AH-3Δ<i>galU</i>:<i>glgA</i>. double mutant. (B) Core oligosaccharide obtained from the slow LPS migration band from AH-3Δ<i>galU</i>:<i>glgA</i> harbouring the AH-3 <i>glgA</i> (pBAD33-GlgA). anhKdo, an anhydro form of Kdo; M_r, calculated molecular mass (Da).</p

Biofilm values of several <i>Aeromonas</i> strains using the method of Pratt and Kolter [35].

<p>Biofilm values of several <i>Aeromonas</i> strains using the method of Pratt and Kolter <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035707#pone.0035707-Pratt1" target="_blank">[35]</a>.</p