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PubMed1983

Plasmids encoding trimethoprim resistance in bacterial isolates from man and pigs.

Trimethoprim (Tp) resistant Gram negative bacteria were isolated from humans and pigs. The bacterial hosts were characterized by their resistance pattern and biotype. The presence of transferable Tp plasmids was demonstrated in 86% of 59 porcine isolates and 37% of 49 human isolates. The Tp R-plasmids carried a diversity of resistance determinants such as Tc, Cm, Sp, Sm and Su. Incompatibility tests distinguished two major groups, Inc FIV and Inc N. Thirty of 99 Tp R-plasmids isolated from humans were grouped as Inc FIV and eight as Inc N. The results of molecular weight determination of Tp R-plasmids performed by agarose gel electrophoresis were consistent with the existence of two groups--larger R-plasmids (76 to 104 Md) belonging to Inc FIV and lower molecular weight R-plasmids (25 to 35 Md) belonging to Inc N. Results from this study indicate that the Tp R-plasmids isolated in Perth have evolved independently from those described in Europe and the United Kingdom. There is also evidence for their local spread between Escherichia, Klebsiella, Enterobacter, Citrobacter and Acinetobacter from man and animals.

Animals↗

PubMed1986

Evaluation of a commercial beta-glucuronidase test for the rapid and economical identification of Escherichia coli.

A commercial beta-glucuronidase (beta-GUR) test for the rapid and economical identification of Escherichia coli was evaluated. A total of 762 clinical strains and 228 environmental isolates were studied. More than 95% of the E. coli strains were found to be beta-GUR positive. Thirty-one clinical isolates of Shigella sonnei, 10 of Enterobacter cloacae, eight of Enterobacter aerogenes, nine of Citrobacter freundii and one of Salmonella enteritidis also gave positive results. The enzyme beta-GUR was also detected in two environmental strains of E. cloacae and one C. freundii. A comparative study between the beta-GUR test and the conventional identification system was carried out in 233 consecutive isolates of lactose positive enterobacteria. Agreement was observed in 223 cases and 190 E. coli strains were correctly identified using this test. Discrepancies were found in 10 cases: nine E. coli were beta-GUR negative and one C. freundii was beta-GUR positive. Escherichia coli was the only species positive for both beta-GUR and indole tests. This procedure permits a rapid, easy, precise and inexpensive identification of E. coli. beta-GUR positive Enterobacter strains have not previously been described.

Escherichia coli↗

PubMed1987

A modified conductance medium for the detection of Salmonella spp.

Selenite-cystine/trimethylamine oxide/dulcitol medium has been used in conjunction with conductance instruments to detect the presence of Salmonella spp. in foods and faeces. However, a small but significant number of salmonella strains were missed by this method. The majority of these strains were detected when dulcitol was substituted by mannitol and tested on two separate Malthus conductance instruments. Some strains of Citrobacter freundii and Escherichia coli continued to give false positive results. Attempts are made to explain why the substitution of mannitol for dulcitol gives an improved medium.

Culture Media↗

PubMed1992

Evaluation of coliforms as indicators of water quality in India.

The total and thermotolerant coliform counts in rural drinking water derived from ground water, piped supplies and surface water are reported for a number of areas in India. To evaluate these counts as indicators of recent faecal contamination the total coliforms and thermotolerant coliforms isolated have been identified. Thermotolerant Escherichia coli formed 11.7% of the total coliforms and 75.1% of the thermotolerant coliforms. Citrobacter sp. (20.4%) and Klebsiella sp. (50.9%) were the other common total coliforms isolated and, among the thermotolerant coliforms, Klebsiella sp. (16.4%) was the only other organism frequently encountered. The total coliform counts were significantly correlated with water temperature. The applicability in tropical areas of standards developed for temperate climates is discussed.

Colony Count, Microbial↗

PubMed1992

Analysis of polar lipids from some representative enterobacteria, Plesiomonas and Acinetobacter by fast atom bombardment-mass spectrometry.

Fast atom bombardment-mass spectrometry (FAB-MS) was used to analyse lipid extracts of bacteria to assess its usefulness for analysing anionic phospholipids of potential chemotaxonomic value. The following micro-organisms were tested: Acinetobacter calcoaceticus, Acinetobacter sp., Citrobacter freundii, Enterobacter cloacae (2 strains), Escherichia coli (3 strains), Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Plesiomonas shigelloides, Proteus mirabilis (3 strains), Serratia liquefaciens and Serratia marcescens. Negative-ion spectra provide data for twenty-seven major carboxylate anions (m/z 209-325) and for thirty-seven major phospholipid anions (m/z 645-774). Generally, the largest carboxylate peaks were due to 16:1, 16:0, cyc17 and 18:1 while the largest phospholipid anion peaks were due to PE(32:1), PE(33:1), PE(34:1), PE(34:2), PG(30:2), PG(31:2), PG(32:2), PG(34:1) and PS(33:0). However, quantitative differences were observed. For example, Acinetobacter lacked PE (33:1) but had exceptionally high peaks at m/z 748, PS(33:0), and m/z 281, octadecanoate. Unknown 'carboxylate' peaks were detected at m/z 254, 256, 261, 268, 282 and 301. In some cases, unknown peaks appeared to constitute possible homologous series being separated by delta m/z of 14(identical to methylene). For chemotaxonomic purposes, the complexity of the data required numerical analysis. Using the Pearson coefficient of linear correlation, as a measure of association, it was possible to compare all strains analysed. Typical results for strain comparisons were as follows: Ent. cloacae vs Ent. cloacae, r = 0.90 (Ent. cloacae vs Ac. calcoaceticus, r = 0.46). Thus FAB-MS represents an excellent means of obtaining large quantities of data on polar lipids of a range of bacterial isolates, which may be suitable for chemotaxonomic purposes.

Acinetobacter↗

PubMed1993

Formation of vitamins by pure cultures of tempe moulds and bacteria during the tempe solid substrate fermentation.

The formation of water soluble vitamins (vitamin B12, vitamin B6, riboflavin, thiamine, nicotinic acid and nicotinamide) during the tempe solid substrate fermentation was investigated. The role of several strains of Rhizopus oligosporus, R. arrhizus, and R. stolonifer and the role of several bacteria in the vitamin formation process were checked. All fungal and bacterial strains were isolated from Indonesian tempe and soaking water samples. The Rhizopus strains formed riboflavin, nicotinic acid, nicotinamide and vitamin B6. The final concentrations of these substances depended on the different strains involved and on the fermentation time. Isolates of R. oligosporus were generally the best vitamin formers. The moulds did not produce physiologically active vitamin B12. The thiamine content decreased during fermentation. The addition of bacteria, which had been selected in a screening for vitamin B12 production, resulted in an increase of physiologically active vitamin B12. Citrobacter freundii and Klebsiella pneumoniae showed the best formation capabilities. Furthermore, the bacteria produced riboflavin and vitamin B6 in addition to the moulds. The influence of Rhizopus on the vitamin B12 formation of Cit. freundii was also investigated. The vitamin content of tempe that was fermented with the mould and the bacterium was three times as high as a control fermentation with Cit. freundii only.

Bacteria↗

PubMed1995

Detection of Escherichia coli in potable water using direct impedance technology.

Direct impedance measurement utilizing a medium previously described as being specific for Escherichia coli and which contains trimethylamine N-oxide (TMAO) and glucuronic acid was used to detect E. coli in water samples. The system was compared with the Colilert presence/absence test and the United Kingdom standard membrane filtration technique using membrane lauryl sulphate broth. The impedance method correlated well with both the traditional membrane method (93%) and the Colilert method (93.95%) for a number of different water types. No interference from Citrobacter spp. (as reported in previous studies) was detected in this study although some Salmonella spp. did give false-positive results. The data presented here suggest that the use of direct impedance may offer an alternative to conventional methods for the detection of E. coli in water.

Bacteriological Techniques↗

PubMed2006

Characterization of the Enterobacteriaceae isolated from an artisanal Italian ewe's cheese (Pecorino Abruzzese).

AIMS: To evaluate some physiological characteristics of the Enterobacteriaceae isolated from Pecorino cheese. METHODS AND RESULTS: The production of organic acids, secondary volatile compounds, biogenic amines (BA) and the lipolytic and proteolytic activities of Citrobacter braakii, Enterobacter sakazakii, Escherichia coli, Kluyvera spp., Salmonella enterica ssp. arizonae and Serratia odorifera strains were determined in skim milk after 48 h of fermentation at 30 degrees C. The proteolytic activity observed only in Ser. odorifera and Kluyvera spp. was confirmed by the peptide profiles of the pH 4.6-insoluble fraction using RP-HPLC; however, the lipase activity was evidenced in all the isolates of E. coli, Kluyvera spp. and Salm. enterica ssp. arizonae. During fermentation, all the strains utilized citric acid and produced significant quantities of putrescine followed by histamine, spermine and spermidine as well as acetic and lactic acid. Moreover, the major volatile compounds produced were ethanol, 2,3-butanedione, 3-hydroxy-2-butanone, 2-heptanone and acetone. CONCLUSIONS: The Enterobacteriaceae of dairy origin possess many metabolic activities that could affect the sensory quality of the cheese in which they grow during ripening. SIGNIFICANCE AND IMPACT OF THE STUDY: The important physiological characteristics possessed by Enterobacteriaceae confirm the complexity of the microbiota of Pecorino Abruzzese cheese, which influences the typical sensory properties of this product.

Acetic Acid↗

PubMed2006

FT-IR microspectroscopy for early identification of some clinically relevant pathogens.

AIMS: To investigate the potentials and limitations of Fourier transform-infrared (FT-IR) microspectroscopy as a tool to identify, at the level of microcolonies, pathogenic bacteria frequently isolated in the clinical environment. METHODS AND RESULTS: A total of 1570 FT-IR spectra from 164 gram-positive and gram-negative bacteria isolated from patients were recorded from 6 to 10-h old microcolonies of 50-150 microm size. A classification of 100% was obtained for the most frequent gram-positive bacteria, such as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Enterococcus faecium at the species level. An average accuracy of about 80% was reached with Gram negative bacteria from the Enterobacteriaceae and Pseudomonaceae families; Enterobacter aerogenes, Enterobacter cloacae, Klebsiella spp., and Citrobacter koseri; and Proteus mirabilis and Escherichia coli. Results were comparable with FT-IR measurements on dried suspensions from 18-h cultures. CONCLUSIONS: Early identification of young microcolonies is feasible with FT-IR microscopy with a very high accuracy for gram-positive bacteria. Some improvement in the transfer of microcolonies is necessary to increase the accuracy for gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Combination of FT-IR microscopy and multivariate data analysis could be a complementary, rapid, and reliable tool for screening and discriminating, at species and subspecies level, micro-organisms of clinical, food-borne, or environmental origins.

Animals↗

PubMed2007

Both sulfate-reducing bacteria and Enterobacteriaceae take part in marine biocorrosion of carbon steel.

AIMS: In order to evaluate the part played in biocorrosion by microbial groups other than sulfate-reducing bacteria (SRB), we characterized the phylogenetic diversity of a corrosive marine biofilm attached to a harbour pile structure as well as to carbon steel surfaces (coupons) immersed in seawater for increasing time periods (1 and 8 months). We thus experimentally checked corroding abilities of defined species mixtures. METHODS AND RESULTS: Microbial community analysis was performed using both traditional cultivation techniques and polymerase chain reaction cloning-sequencing of 16S rRNA genes. Community structure of biofilms developing with time on immersed coupons tended to reach after 8 months, a steady state similar to the one observed on a harbour pile structure. Phylogenetic affiliations of isolates and cloned 16S rRNA genes (rrs) indicated that native biofilms (developing after 1-month immersion) were mainly colonized by gamma-proteobacteria. Among these, Vibrio species were detected in majority with molecular methods while cultivation techniques revealed dominance of Enterobacteriaceae such as Citrobacter, Klebsiella and Proteus species. Conversely, in mature biofilms (8-month immersion and pile structure), SRB, and to a lesser extent, spirochaetes were dominant. CONCLUSIONS: Corroding activity detection assays confirmed that Enterobacteriaceae (members of the gamma-proteobacteria) were involved in biocorrosion of metallic material in marine conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: In marine biofilms, metal corrosion may be initiated by Enterobacteriaceae.

Base Sequence↗

PubMed1989

Microbial contamination of cosmetics and personal care items in Egypt--eye shadows, mascaras and face creams.

We examined a total of 150 samples, including 27 eye shadows, 27 mascaras and 96 face creams, for their microbial contents. Mascaras were generally more contaminated than eye shadows. More than 75% of the examined eye shadows contained fewer than 100 c.f.u./g aerobic bacterial count compared to 63% of the mascaras examined. Viable bacteria were not recovered from 61% and 48% of the eye shadows and mascaras respectively. While 4% of the eye shadows were heavily contaminated (contained more than 10(4) c.f.u./g), 15% of the mascaras were as heavily contaminated (with more than 10(4) c.f.u./ml of bacteria). Face creams were generally more heavily contaminated than eye shadows and mascaras. More than 70% of the examined creams contained more than 100 c.f.u./g of bacteria compared to 23% and 37% of eye shadows and mascaras respectively. Only 5% of the face creams were heavily contaminated. However, 27% of the creams were contaminated with more than 10(3)-10(4) c.f.u./g of bacteria compared to none in this range for both eye shadows and mascaras. Qualitative tests for detection of hazardous bacteria showed that none of the eye shadows were contaminated with any of those micro-organisms. Out of nine items of a specific brand of mascara, three isolates of Pseudomonas aeruginosa, one isolate of Citrobacter freundii and one isolate of Klebsiella pneumonia were detected. Among the creams, two brands showed the highest contamination levels with more than 85% of the tested samples containing more than 10(3) c.f.u./g fungi and at least 10(4) c.f.u./g bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria↗

PubMed1989

Microbial contamination of cosmetics and personal care items in Egypt--body lotions and talcum powders.

We examined a total of 54 samples, including 18 body lotions and 36 talcum powders, for their total aerobic bacterial, coliform and fungal counts. We also carried out anaerobic bacterial counts for talcum powder as well as tests to detect some potentially hazardous bacteria in all tested samples. Talcum powders were more heavily contaminated with bacteria and fungi than body lotions. More than 40% of the tested body lotions contained no viable bacteria or less than 100 c.f.u./g. while all the talcum powders tested contained more than 100 c.f.u./g. Thirty per cent of the talcum powders were contaminated with 10(4) c.f.u./g. and none of the body lotions were contaminated to that extent. No coliforms were recovered from any of the body lotions, while 17% of the talcum powder examined contained coliforms in the range of 230-500 c.f.u./g. Staphylococcus spp. were detected in 18 samples of both talcum powders and body lotions, three of these Staphylococci were of the aureus type. Three samples of talcum powder contained E. coli, two samples contained Enterobacter agglomerans and one sample contained Citrobacter freundii. Seventy per cent of the body lotions showed no fungal counts, while 83% of the talcum powders examined were contaminated with fungi and most of the contaminated talcum powders contained more than 100 fungal cells/g. With regard to the anaerobic bacterial counts for talcum powders, 50% of the samples showed no counts while the other 50% contained less than 100 c.f.u./g. Four samples were contaminated with Clostridium perfringens, although C. tetani was not recovered from any of the samples.

Bacteria, Anaerobic↗

PubMed1997

The responses of Lucilia cuprina to odours from sheep, offal and bacterial cultures.

The responses of gravid female Lucilia cuprina to odours from sheep urine, faeces and gut mucus, and to odours from liver/sodium sulphide mixtures was tested using a bioassay which measured the movement and probing response of walking flies. The same bioassay was used to test the response to odours from cultures of bacteria isolated from liver/sodium sulphide and liver/water mixtures. A significant movement towards odours from faeces, gut mucus and urine was observed. Odours from cultures of the bacteria Proteus mirabilis, Dermatophilus congolensis and Serratia marcescens also elicited significant movement. A probing response was elicited by odours from gut mucus, fresh urine, liver/sodium sulphide mixtures and cultures of P.mirabilis, D.congolensis and gram-positive species. Odours from cultures of Pseudomonas aeruginosa, Enterobacter aerogenes and Citrobacter freundii did not elicit significant movement or probing. The movement and probing responses are discussed with reference to the possible uses of the substances tested as a bait for attracting L.cuprina.

Animals↗

PubMed1989

A novel, non-invasive promoter probe vector: cloning of the osmoregulated proU promoter of Escherichia coli K12.

We have constructed a novel promoter probe plasmid pSB40, containing a unique lac-alpha-tetracycline marker gene tandem, which allows for both positive and negative selection of active promoters. Promoters cloned in pSB40 can be readily mobilized as EcoRI cassettes. Using this vector we have performed a non-invasive analysis of the E. coli chromosome for promoters regulated by osmotic upshift. Only one such promoter, subsequently identified as part of the proU operon, was isolated. A sequence of 253 bp, sufficient to mediate osmotic regulation of the proU promoter, was defined. This E. coli promoter was normally regulated in Salmonella typhimurium, Klebsiella and Citrobacter but not in Shigella. A proU-luxAB fusion plasmid was constructed and used to monitor in vivo real-time kinetics of proU induction following osmotic upshock.

Base Sequence↗

PubMed1989

Signalling proteins in enterobacterial AmpC beta-lactamase regulation.

The cloned Citrobacter freundii ampC beta-lactamase is inducible in the presence of its regulatory gene ampR in Escherichia coli (Lindberg et al., 1985). The basal level of expression and inducibility are affected by two E. coli proteins encoded by the closely linked ampD and ampE genes. Deletion of both genes led to constitutive ampR-dependent overproduction of beta-lactamase, whereas an out-of-frame deletion in AmpD caused the basal expression to increase two-fold. This ampD1 mutant was inducible at lower beta-lactam concentrations than the wild type. An IS1 insertion in ampD was polar on ampE expression and increased basal beta-lactamase expression 30-fold while mediating a semi-constitutive phenotype. AmpE expressed from a recombinant plasmid in an ampD-ampE deletion mutant reduced basal beta-lactamase expression to wild-type levels but did not markedly reduce beta-lactam resistance since the cells became hyperinducible. In the absence of AmpD, increasing levels of AmpE therefore decrease the basal expression of AmpC beta-lactamase in an AmpR-dependent manner. AmpD modulated the response exerted on beta-lactamase expression by AmpE. The ampD gene encodes a 20.5kD cytoplasmic protein while the 32.1kD ampE gene product is an integral membrane protein with a likely ATP-binding site between the second and third putative transmembrane region. Since neither AmpD nor AmpE are needed for beta-lactam induction and since these proteins could not be covalently labelled by benzylpenicillin, they are not thought to act as beta-lactam-binding sensory transducers. Instead it is suggested that AmpD and AmpE sense the effect of beta-lactam action on peptidoglycan biosynthesis and relay this signal to AmpR.

Alleles↗

PubMed1994

A new class of proteins regulating gene expression in enterobacteria.

YmoA and Hha are highly similar bacterial proteins downregulating gene expression in Yersinia enterocolitica and Escherichia coli, respectively. The phenotype of ymoA mutants evokes that of mutants affected in some histone-like proteins. This paper describes complementation of a ymoA mutation in Y. enterocolitica by the hha gene from E. coli. We show that YmoA and Hha are not only very similar proteins but that they are functionally interchangeable. Genetic experiments indicate that Hha can also stimulate transposition events in vivo. By Southern blot analysis we detected hha-homologous genes at least in Citrobacter diversus, Shigella flexneri, Shigella dysenteriae, Klebsiella pneumoniae and Salmonella typhimurium. We suggest that both YmoA and Hha belong to a new family of proteins downregulating gene expression in different enterobacteria.

Amino Acid Sequence↗

PubMed1994

Unique fimbriae-like structures encoded by sefD of the SEF14 fimbrial gene cluster of Salmonella enteritidis.

The SEF14 gene cluster of Salmonella enteritidis was recently shown to contain three genes, sefABC, encoding a unique fimbrin, and proteins homologous to fimbrial chaperones and outer membrane proteins (ushers), respectively. A fourth open reading frame, designated sefD, was found immediately downstream of sefABC and overlapping sefC. The translated protein sequence of sefD was unique, but the composition was similar to that of other bacterial fimbriae. SefD was produced in abundance by wild-type S. enteritidis as shown by Western blot analysis using antibodies raised to affinity-purified, recombinant SefD. Furthermore, unusually long, thin, fimbriae-like structures were evident on S. enteritidis and Escherichia coli by immunoelectron microscopy, but in other bacterial species SefD was expressed as amorphous material. Therefore, in S. enteritidis and E. coli, SefD is the predominant structural subunit of SEF18. The SEF18 fimbriae-like structures were shown to be serologically distinct from the three known S. enteritidis fimbriae SEF14, SEF17 and SEF21. Furthermore, SEF18 was still produced in sefA insertion mutants, indicating that SEF14 and SEF18 were structurally distinct. Thus, the SEF14 gene cluster is the first example in the Enterobacteriaceae of a gene cluster that encodes two fimbrin-like proteins, which are assembled into two distinct cell-surface structures, SEF14 and SEF18. DNA hybridization and Western blot analyses showed that SefD was widely distributed among the Enterobacteriaceae and was present in E. coli, Shigella, Enterobacter, Citrobacter, Erwinia, Hafnia, Klebsiella, Providencia, and Proteus but not in the non-Enterobacteriaceae Gram-negative bacteria Pseudomonas and Aeromonas, or in Gram-positive bacteria Bacillus or Staphylococcus.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗

PubMed2006

The enteropathogenic Escherichia coli type III secretion system effector Map binds EBP50/NHERF1: implication for cell signalling and diarrhoea.

Enteropathogenic Escherichia coli (EPEC) is the single most important contributor to child diarrhoea in developing countries. Nevertheless, the mechanism responsible for EPEC diarrhoea remains elusive. Using the yeast two-hybrid system to determine the target host cell protein of the EPEC type III secretion system effector Map led to identification of ezrin/radixin/moesin (ERM)-binding phosphoprotein 50 (EBP50), also known as Na+/H+ exchanger regulatory factor 1 (NHERF1). Protein interaction is mediated by the carboxy-terminal Thr-Arg-Leu (TRL) motif of Map and the PSD-95/Disk-large/ZO-1 domain 1 (PDZ1) of EBP50/NHERF1. Although EBP50/NHERF1 is recruited to site of EPEC adhesion in a Map-independent mechanism, co-immunoprecipitation and immunostaining revealed that Map binds to, induces proteolysis of, and colocalizes with EBP50/NHERF1 during infection of cultured epithelial cells. The TRL motif of Map was involved in Map-induced filopodia formation and brush border elongation on infected HeLa and Caco-2 cells respectively. As EBP50/NHERF1 regulates ion channels in the intestine we assessed the involvement of Map in diarrhoea using the Citrobacter rodentium mouse model of EPEC. We report significantly greater diarrhoea following infections with wild-type C. rodentium compared with C. rodentiumDeltamap. These results provide new insights into the mechanisms of EPEC diarrhoea.

Actins↗