Hydrogensulphide producing variants of Escherichia coli

Cysteine Hydropersulfide Inactivates β-Lactam Antibiotics with Formation of Ring-Opened Carbothioic S-Acids in Bacteria

Hydrogen sulfide (H₂S) formed during sulfur metabolism in bacteria has been implicated in the development of intrinsic resistance to antibacterial agents. Despite the conversion of H₂S to hydropersulfides greatly enhancing the biochemical properties of H₂S such as antioxidant activity, the effects of hydropersulfides on antibiotic resistance have remained unknown. In this work, we investigated the effects of H₂S alone or together with cystine to form cysteine hydropersulfide (CysSSH) on the activities of antibacterial agents. By using the disc diffusion test, we found that CysSSH treatment effectively inactivated β-lactams of the penicillin class (penicillin G and ampicillin) and the carbapenem class (meropenem). These β-lactams were resistant to treatment with H₂S alone or cystine alone. In contrast, cephalosporin class β-lactams (cefaclor and cefoperazone) and non-β-lactam antibiotics (tetracycline, kanamycin, erythromycin, and ofloxacin) were stable after CysSSH treatment. Chromatographic and mass spectrometric analyses revealed that CysSSH directly reacted with β-lactams to form β-lactam ring-opened carbothioic S-acids (BL-COSH). Furthermore, we demonstrated that certain bacteria (e.g., Escherichia coli and Staphylococcus aureus) efficiently decomposed β-lactam antibiotics to form BL-COSH, which were transported to the extracellular space. These data suggest that CysSSH-mediated β-lactam decomposition may contribute to intrinsic bacterial resistance to β-lactams. BL-COSH may become useful biomarkers for CysSSH-mediated β-lactam resistance and for investigation of potential antibacterial adjuvants that can enhance the antibacterial activity of β-lactams by reducing the hydropersulfides in bacteria.

Genomic Characterization of New Variant of Hydrogen Sulfide (H2S)-Producing Escherichia coli with Multidrug Resistance Properties Carrying the mcr-1 Gene in China †

Colistin is considered to be a ‘last-resort’ antimicrobial for the treatment of multidrug-resistant Gram-negative bacterial infections. Identification of Enterobacteriaceae, carrying the transferable colistin resistance gene mcr-1, has recently provoked a global health concern. This report presents the first detection of a hydrogen sulfide (H₂S)-producing Escherichia coli variant isolated from a human in China, with multidrug resistance (MDR) properties, including colistin resistance by the mcr-1 gene, which could have great implications for the treatment of human infections.

Role of hydrogen sulfide in mercury resistance determined by plasmid of Clostridium cochlearium T-2

Mercury resistance of Clostridium cochlearium T-2P was found to be controlled by a different mechanism from those reported so far since no mercury-reducing activity was detected in this strain. The H2S generating ability as well as the demethylating activity in this bacterium was eliminated by the treatment of the cured acridine dye and recovered by the conjugation of the cured strain with the parent strain. In addition, the strain which lost their abilities to generate H2S and to decompose methylmercury, showed higher sensitivity to mercurials than the parent strain. From these results, the genes conferring both the activities seemed to reside on the plasmid and the mechanism of mercury resistance was probably based on a detoxification mechanism involving methylmercury decomposition and inactivation of the inorganic mercury with H2S.

Spurious hydrogen sulfide production by Providencia and Escherichia coli species

Hydrogen sulfide production was noted in two Escherichia coli strands and one Provaidenica alcalifaciens (Proteus inconstans A) strain isolated from clinical stool specimens durin the summer of 1979. An investigation into this phenomenon revealed the predence of Eubacterium lentum, an anaerobe, growing in synergism with the Enterobacteriaceae and producing H2s. The implications of this association are discssed with reference to clinical microbiology laboratory practice.

his-Linked hydrogen sulfide locus of Salmonella typhimurium and its expression in Escherichia coli

A his-linked H2S locus of Salmonella typhimurium has been further defined by direct isolation of H2S mutants. Expression of this locus in Escherichia coli has been demonstrated.

Seasonal occurrence and distribution of microbial indicators and pathogens in the Rhode River of Chesapeake Bay

The seasonal incidence and occurrence of indicator organisms and pathogens were studied at four sites in the Rhode River, a subestuary of Chesapeake Bay. The highest frequency of occurrence of total and fecal coliforms and fecal streptococci was in Muddy Creek, a marsh area receiving pasture land runoff. Second highest frequency of occurrence of these bacteria was in Cadle Creek, a populated area. Lowest measurements of these parameters were obtained at stations in the central portion of the Rhode River. No Salmonella spp. were detected by the methods employed in this study. However, it is concluded that if these organisms are present, the concentrations are less than or equal to 1 organism per liter. The presence of Clostridium botulinum was detected in 12% of the samples tested.

Hydrogen sulfide-producing variants of Escherichia coli

Seventeen strains of H(2)S-producing variants of Escherichia coli were isolated from specimens submitted for microbiological study (ten from stool, five from urine, and two from postmortem material). Production of H(2)S was unstable in several strains; however, other than their production of H(2)S, all strains closely resembled typical E. coli in their biochemical reactions. In vitro susceptibilities of the H(2)S-producing variants to antimicrobics closely resembled those of typical E. coli in this laboratory.

Biochemical and serological characterization of hydrogen sulfide-positive variants of Escherichia coli

Over 200 H(2)S-positive, gram-negative rods have been characterized by standard biochemical and serological techniques. The results indicate that the isolates are H(2)S-positive variants of Escherichia coli. Comparison of the variants with biochemically typical E. coli suggests that they represent a rather limited subgroup within the species. The H(2)S-positive strains were more resistant to antibiotics than the typical strains; 54% of the H(2)S-positive isolates were resistant to three or more antibiotics compared with only 25% of the typical strains. Similar differences were also seen in the distribution of O and H antigens and in the results of certain biochemical tests.