agar and Gram-Negative-Bacterial-Infections

The gold standard method to isolate and identify Taylorella equigenitalis, the contagious agent of equine metritis, is the culture method according to the World Organisation for Animal Health Terrestrial Manual. No selective T. equigenitalis chocolate agar medium has been developed since the 1980s and the existing media show limited performances due to the fastidious nature of T. equigenitalis and the presence of interfering bacteria in the genital tract of equines. Here, the growth rates of 6 T. equigenitalis strains and 7 non-T. equigenitalis strains were compared on Timoney's selective medium formulated with 5 different basal agars (Columbia, Eugon, Blood, Mueller-Hinton and Tryptose Blood) provided by 2 to 4 suppliers per basal agar. The impact of glucose and/or Vitox supplementation was also investigated. Overall, the performance of selective T. equigenitalis media could be improved by substituting Eugon or Columbia agar with Blood, Mueller-Hinton or Tryptose Blood agar. It is nevertheless essential to validate the basal agar/supplier pair using a panel of T. equigenitalis strains. Furthermore, our findings confirm the need to supplement the selective media with a mixture of amino acids, nucleotides, and organic, mineral and vitamin compounds, translated here by Vitox supplementation.

Topics: Agar; Animals; Chocolate; Gram-Negative Bacterial Infections; Horse Diseases; Horses; Taylorella equigenitalis

Despite the increasing reliance on polymyxin antibiotics (polymyxin B and colistin) for treatment of multidrug-resistant Gram-negative infections, many clinical laboratories are unable to perform susceptibility testing due to the lack of accurate and reliable methods. Although gradient agar diffusion is commonly performed for other antimicrobials, its use for polymyxins is discouraged due to poor performance characteristics. Performing gradient agar diffusion with calcium enhancement of susceptibility testing media has been shown to improve the identification of polymyxin-resistant isolates with plasmid-mediated resistance (

Topics: Agar; Anti-Bacterial Agents; Calcium; Colistin; Culture Media; Disk Diffusion Antimicrobial Tests; Drug Resistance, Multiple, Bacterial; Enterobacteriaceae; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Pseudomonas aeruginosa

Topics: Aerobiosis; Agar; Bacteriological Techniques; Carbon Dioxide; Colony Count, Microbial; Culture Media; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans

Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics.

Topics: Agar; Animals; Anti-Bacterial Agents; Brachyspira; Diarrhea; Diterpenes; Drug Resistance, Bacterial; Gram-Negative Bacterial Infections; Microbial Sensitivity Tests; Swine; Swine Diseases

Direct plating of simulated stool specimens on MacConkey agar (MCA) with 10-μg ertapenem, meropenem, and imipenem disks allowed the establishment of optimal zone diameters for the screening of carbapenem-resistant Gram-negative rods (CRGNR) of ≤ 24 mm (ertapenem), ≤ 34 mm (meropenem), and ≤ 32 mm (imipenem).

Topics: Agar; Anti-Bacterial Agents; Bacterial Proteins; beta-Lactam Resistance; beta-Lactamases; Carbapenems; Culture Media; Feces; Gram-Negative Aerobic Rods and Cocci; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests

Selective screening media for the detection and identification of Aeromonas strains are needed to guide primary isolation procedures in the clinical laboratory. This study compared the selective CromoCen® AGN chromogenic agar medium for the detection and identification of Aeromonas strains that were isolated from various samples against the conventional selective agar media that are commonly used for the isolation of this organism in food, environmental and clinical samples. The Miles and Misra and ecometric methods were used to evaluate the microbiological performance of CromoCen® AGN chromogenic agar medium, which was shown to be satisfactory. A total of 14 reference Aeromonas strains, 44 wild strains and 106 clinical stool specimens were examined using both non-chromogenic selective agars that are commonly used for Aeromonas isolation and CromoCen® AGN agar. The latter exhibited 94.73% sensitivity and 100% specificity for the various samples. On CromoCen® AGN agar medium, Aeromonas formed colonies with light green, greenish and salmon pigments with or without a surrounding wide transparent zone (halo) of 2-3mm in diameter around the entire border. This medium is recommended for the isolation and potential identification of the Aeromonas genus.

Topics: Aeromonas; Agar; Bacteriological Techniques; Child; Chromogenic Compounds; Culture Media; Feces; Gram-Negative Bacterial Infections; Humans; Mass Screening; Selection, Genetic; Sensitivity and Specificity

Stenotrophomonas maltophilia (Smalto) is a prominent nosocomial pathogen, commonly isolated in the hospital environment. Multiple Smalto nosocomial outbreaks have been linked to contaminated water sources. This study aimed to develop a medium able to ease healthcare environment Smalto isolation.. Financed, from March 2007 to June 2008, by a university hospital of Amiens' clinical research program, this study allowed Stenotrophomonas maltophilia selective medium with coloured indicator (SM2i) development. SM2i is constituted of Mueller Hinton agar (MH), maltose, DL-methionine, bromothymol blue. The mixture sterilized is refreshed at 50 degrees C, its pH adjusted to 7.1, and render selective by addition of vancomycin, imipenem and amphotericin B. Then, SM2i agar is sunk into 90 cm diameter Petri dish dated and stored at 4 degrees C for 4 weeks. SM2i is developed using Pasteur Institute culture type collection (CIP) strains of Smalto, Burkholderia cepacia, Pseudomonas aeruginosa (Psa) and a Smalto strain of our hygiene laboratory collection. It was validate on Psa imipenem-resistant and Enterococcus faecium vancomycin-resistant strains, then, tested on cold water first jet and faucet cotton-swabs samples. SM2i tests were made in comparison with the MH agar, MH agar plus four paper disks loaded 10 microg of imipenem and Cetrimed agar. Its sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, accuracy, likehood-ratio (LR) and Youden index have been determined.. SM2i agar is better in culturing Smalto test-strains. On SM2i, Smalto colonies are smooth, round, greeny, olive or lime green, have a green olive centre with a peripheral lighter or a dark green centre with an olive green suburb surrounded by a blue halo. SM2i is a selective, specific, predictive, accurate medium to search for Smalto in healthcare environment. In 122 pairs of cold water first jet and taps cotton-swabs samples, Smalto was isolated from 14.8% of water samples, 10.7% of cotton-swabs samples. It was isolated alone in 6.6% of water samples and 2.5% of swab samples. Thus, smalto has biocontaminated 17.2% of cold water taps. Compared to MH agar, SM2i sensitivity, specificity, PPV, NPV, accuracy, LR were 100, 100, 100, 100, 100% and infinity, and 87.5, 100, 100, 98.1, 98.4% and infinity for water and cotton-swabs samples respectively.. SM2i is a selective, specific, predictive medium which can allow easily isolating and identifying accurately Smalto in environmental samples. Its evaluation on clinical samples is on going.

Topics: Agar; Bacteriological Techniques; Cross Infection; Culture Media; Equipment Contamination; Gram-Negative Bacterial Infections; Humans; Indicators and Reagents; Predictive Value of Tests; Sensitivity and Specificity; Stenotrophomonas maltophilia; Water Microbiology

The detection of carbapenemases in Gram-negative bacilli is important for optimal patient treatment and to control spread of the resistance. The modified Hodge test can detect carbapenemase-producing Gram-negative bacilli. In this study, we compared the performance of MacConkey agar and Mueller-Hinton agar for metallo-β-lactamase (MBL) and OXA carbapenemase screening. Overall, the performance of Hodge test was better with MacConkey agar due to enhanced release of β-lactamases from the cells in the presence of bile compounds. Concomitant use of the modified Hodge test could resolve most of the problems with uncertain double-disk synergy tests in MBL detection.

Topics: Agar; Anti-Bacterial Agents; Bacterial Proteins; beta-Lactamases; beta-Lactams; Culture Media; Ertapenem; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Imipenem; Mass Screening; Microbial Sensitivity Tests

Topics: Aeromonas; Agar; Anti-Bacterial Agents; Carbanilides; Cefsulodin; Culture Media; Electron Transport Complex IV; Feces; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Novobiocin

The findings from a preliminary assessment of a new instrument designed for the inoculation and spreading of specimens for microbiological analysis onto agar plates are described. The study found that the instrument was able to select full or biplates from a number of input cassettes, each containing different agar types. Samples were then inoculated by the instrument onto the agar surfaces and spread by a novel plastic applicator. Following this, the instrument labeled the plates and sorted them into a number of specified output stations. It was found that the instrument was able to inoculate and spread samples over a greater proportion of the agar plate surface than the manual loop-to-plate method. As a consequence, up to 44% more usable colonies were produced per plate from clinical specimens and standard cultures. Viable counts showed that the instrument was able to detect as few as 10(2) CFU/ml in fluids and also facilitated the enumeration of organisms, particularly in specimens such as urine.

Topics: Agar; Automation; Bacteriological Techniques; Blood; Colony Count, Microbial; Culture Media; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Humans; Specimen Handling; Urine

With the growing frequency of extended-spectrum beta-lactamases (ESBL) among Enterobacteriaceae, treatment of Gram-negative nosocomial infections requires rapid and reliable detection of this enzyme. Quicolor agar (QC agar) (Salubris Inc., Massachusetts, USA) is a novel chromogenic agar medium changing colour within 4 to 6 h due to the metabolic activity of growing bacteria. This study investigated the use of QC agar compared to Mueller Hinton agar (MH) for the detection of ESBL using disk diffusion and E-test. 100 Enterobacteriaceae isolated at Hacettepe University Hospital, of which 50 were predetermined to be ESBL positive and 50 as negative using the CLSI disk diffusion ESBL (phenotypic confirmatory test) criteria. For disk diffusion and E-test, cefotaxime+/-clavulanate (CT/CTL) and ceftazidime+/-clavulanate (TZ/TZL) were used, and for E-test, cefepime+/-clavulanate (PM/PML) was also used. QC agar rapid ESBL results for all strains were in agreement with the standard overnight procedure. All 50 ESBL positives were detected by both methods. For the 50 ESBL negatives, QC agar rapid results from E-test and disk diffusion were in complete accordance with the overnight MH results. Moreover, E-test detected 8 additional ESBL positive strains that disk diffusion missed. For disk diffusion, CT/CTL alone detected all 50 ESBL positives while TZ/TZL alone missed 5 ESBL positives. E-test CT/CTL alone confirmed all 50 ESBL positives and identified 4 additional ESBL-positive strains. When used together, E-test CT/CTL, TZ/TZL and PM/PML identified a total of 58 ESBL positives among the 100 strains tested. QC agar can be used for rapid and reliable ESBL detection within 4 to 6 h, using disk diffusion and E-test ESBL reagents. This rapid method should be further validated using genotype characterized ESBL and other beta-lactamase positive strains.

Topics: Agar; beta-Lactam Resistance; beta-Lactamases; Cross Infection; Disk Diffusion Antimicrobial Tests; Enterobacteriaceae; Gram-Negative Bacterial Infections; Humans

Topics: Aeromonas; Agar; Bacteriological Techniques; Carbanilides; Coloring Agents; Diarrhea; Feces; Gram-Negative Bacterial Infections; Humans; Quaternary Ammonium Compounds

A new selective medium, cefoperazone MacConkey agar (CMA), was developed for primary isolation of Laribacter hongkongensis from stool. Its performance in quantitative recovery and in a clinical evaluation of 4,741 human diarrheal stool specimens was superior to that of charcoal cefoperazone deoxycholate agar. In addition, with CMA, Arcobacter butzleri was unexpectedly isolated from the stools of six patients.

Topics: Agar; Anti-Bacterial Agents; Bacteriological Techniques; Cefoperazone; Culture Media; Diarrhea; Feces; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Neisseriaceae

Topics: Agar; Animals; Cattle; Diagnosis, Differential; Enzyme Inhibitors; Eosine Yellowish-(YS); Escherichia coli Infections; Female; Food Contamination; Gram-Negative Bacterial Infections; Mastitis, Bovine; Methylene Blue; Sensitivity and Specificity; Specimen Handling

Susceptibility testing of Eikenella corrodens is usually performed by a Mueller-Hinton sheep blood agar dilution (AD) method. However, this method is impractical for testing only a few strains. We compared AD with the broth microdilution method using Haemophilus test medium (HTM) in order to determine the susceptibility of 36 clinical isolates of E. corrodens to eight antimicrobial agents. MICs obtained by the HTM method yielded 95.5 and 84% agreement (within 2 and 1 log2 dilutions, respectively) with those obtained by AD. The HTM method with incubation in CO2 for 48 h was highly reproducible and constitutes an easy alternative for antimicrobial susceptibility testing of E. corrodens.

Topics: Agar; Anti-Bacterial Agents; Culture Media; Eikenella corrodens; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests

A new chromogenic plate medium, CHROMagar Orientation, was evaluated for use in the differentiation and presumptive identification of gram-negative bacilli and Enterococcus species by a multipoint inoculation (replicator) technique. In this study, 1,404 gram-negative bacilli and 74 enterococcal isolates were tested on CHROMagar Orientation. Six control American Type Culture Collection strains were also included with the testing to ensure quality control of the media. Of the Escherichia coli isolates (n = 588) tested, 99.3% produced a pink-to-red color. Only in four isolates that were O-nitrophenyl-beta-D-galactopyranoside (ONPG) negative did this result differ. Proteus mirabilis and P. vulgaris were well differentiated on this medium. P. mirabilis (n = 184) produced a clear colony with diffusible brown pigment around the periphery. By contrast, 15 of 16 P. vulgaris isolates produced bluish-green colonies with a slight brown background. All Aeromonas hydrophila isolates (n = 26) tested produced clear to pink colonies at 35 to 37 degrees C. This colony color changed to blue after 2 to 3 h of incubation at room temperature. A. hydrophila exhibited stronger color and better growth at 30 degrees C. Serratia marcescens (n = 29) demonstrated an aqua blue color that deepened to a darker blue when exposed to room temperature. All enterococcal isolates (n = 74) resulted in a blue color and gave pinpoint colonies on purity subcultures at 35 to 37 degrees C after 18 h of incubation. Similarity in color resulted in failure to discriminate accurately between Klebsiella, Enterobacter, and Citrobacter species. However, these species could be readily differentiated from other members of the family Enterobacteriaceae. Pseudomonas aeruginosa (n = 151) was easily differentiated from members of the Enterobacteriaceae but was less easily distinguishable from other gram-negative nonmembers of the Enterobacteriaceae. The medium was found to facilitate easy visual detection of mixed bacterial isolates in culture. When used in a replicator system, it easily detected mixed growths of organisms which may have otherwise led to false antibiotic susceptibility results. These mixed growths were not obvious on the routine susceptibility testing medium (Isosensitest).

Topics: Agar; Bacterial Typing Techniques; Bacteriological Techniques; Chromogenic Compounds; Color; Culture Media; Enterococcus; Evaluation Studies as Topic; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Gram-Positive Bacterial Infections; Humans; Species Specificity

The aim of the study was to evaluate the chromogenic agar plate CPS ID2 (bioMérieux) and determine its cost-benefit ratio.. A total of 2,193 urinary sediments were processed. The urine culture was carried out in CPS ID2 agar and in cystine-lactose electrolyte deficient (CLED) agar, when needed. Identification of the microorganisms was performed following standard microbiologic procedures through biochemical tests prepared in our laboratory. The identification, from CPS ID2 agar, by direct detection in medium of four metabolic activities: beta-glucuronidase, beta-glucosidase, deaminase, and indol production, was performed following to manufacturer's instructions.. A total of 289 urine cultures were positive, 18 were negative and 34 were contaminated samples. The identification, directly performed from the colonies detected in CPS ID2 agar, was correct in 96% of 166 Escherichia coli, in 92% of 24 Proteus mirabilis and in 97% of 38 enterococci. CPS ID2 agar exhibited 94% and 100% sensitivity and specificity, respectively in E. coli identification, 92% and 100% in P. mirabilis and 97% and 99% in Enterococcus. The use of this new media, CPS ID2, in our laboratory, implies a budgetary increment. However, if commercial galleries are used for routine identification, the cost will be reduced using this new media.. The CPS ID2 agar allows the isolation and direct identification of the most frequent urinary tract pathogens: E. coli, P. mirabilis and Enterococcus in primary isolation medium. Using this medium, bacteriologists will be able to save time and reagents when identifying the most common uropathogens. Furthermore, the use of this medium would reduce costs in some laboratories.

Topics: Agar; Amino Acid Oxidoreductases; Bacterial Proteins; Bacteriological Techniques; beta-Glucosidase; Candida albicans; Candidiasis; Chromogenic Compounds; Cost-Benefit Analysis; Culture Media; Enterobacteriaceae; Enterobacteriaceae Infections; Evaluation Studies as Topic; Glucuronidase; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Humans; Indoles; L-Amino Acid Oxidase; Urinary Tract Infections; Urine

Currently recommended dilution test methods for the determination of antimicrobial susceptibility of Stenotrophomonas (Xanthomonas) maltophilia are labor-intensive and often impractical in many clinical laboratories. We compared the E test with the agar dilution method for susceptibility testing of 176 clinical isolates of S. maltophilia against 16 antimicrobial agents. The MICs obtained by E test correlated well with those determined by the agar dilution method, with an overall agreement of 94%. Very major and major errors occurred infrequently (0.6 to 2.9%) when testing beta-lactam agents, tobramycin, trimethoprim-sulfamethoxazole, and fluoroquinolones. The E test was found to be accurate and easy to perform. For most antimicrobial agents tested against S. maltophilia, the E test is an acceptable alternative susceptibility test method.

Topics: Agar; Diagnostic Errors; Evaluation Studies as Topic; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Reproducibility of Results; Xanthomonas

Ceftazidime was compared with cefotaxime, ceftizoxime, cefmenoxime, cefotiam, cefoperazone, moxalactam, piperacillin, carbenicillin, mezlocillin, cefsulodin and the aminoglycoside antibiotic gentamicin in a series of mouse protection tests. Ceftazidime, together with the other cephalosporin antibiotics and moxalactam were equally effective against infections caused by Staphylococcus aureus with ED50 values ranging from 3.5 to 25 mg/kg. Gentamicin was the most active antibiotic with ED50 values of 0.4 and 1.6 mg/kg. Ceftazidime showed excellent activity against Enterobacteriaceae with ED50 values ranging from 0.2-0.9 mg/kg for Escherichia coli strains, 1.1-13.8 mg/kg for indole positive and negative Proteus spp, and 0.1-25 for Enterobacter cloacae, Klebsiella pneumoniae and Serratia spp. Similar activity against many of the test strains of Enterobacteriaceae was found for gentamicin, cefotaxime, ceftizoxime, cefmenoxime and moxalactam, although cefotiam and cefoperazone were significantly less active than ceftazidime. Ceftazidime was significantly more active than the other beta-lactam antibiotics tested against Pseudomonas aeruginosa infections with ED50 values ranging from 02-108 mg/kg. Only the aminoglycoside antibiotic gentamicin, with ED(50,S) 0.6-6.3 mg/kg, was as effective as ceftazidime. Very poor activity was found for moxalactam, cefoperazone, piperacillin, carbenicillin and mezlocillin against the majority of the test strains of Pseudomonas. The results of these in-vivo indicate that ceftazidime is a promising potential alternative to aminoglycoside antibiotics.

Topics: Agar; Animals; Anti-Bacterial Agents; Bacterial Infections; beta-Lactams; Ceftazidime; Cephalosporins; Colony Count, Microbial; Female; Gentamicins; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Mice; Microbial Sensitivity Tests