Effects of gelatin prepared from calf bones rich in phosphorus on broiler performance, bone characteristics and digestive enzymes activity.

1. Gelatin prepared from calf bones (GCB) is a novel source of high-quality protein and phosphorus. Its inclusion in broiler chicken diets may improve bone strength, plasma and digestive alkaline phosphatase activity (ALP), phosphorus digestibility and performance of broilers. Therefore, di-calcium phosphate in a corn-soy control diet was replaced with 12, 24, and 36 g/kg of GCB in a completely randomised design with four treatments of six replicates and 10 chicks in each pen. The trial lasted from 1 to 42 d of age. 2. Body weight and feed intake were measured weekly. Plasma calcium and phosphorus concentration along with plasma and digestive ALP were assayed throughout the trial. Trypsin, α-amylase, lipase and total protease activity were assayed at 14 and 28 d of age. Tibia ash, calcium and phosphorus content and breaking strength were measured at 14, 28 and 42 d of age. Phosphorus digestibility was measured at 36 d of age. 3. Body weight and feed intake showed no significant differences between controls and diets containing 12 and 36 g/kg GCB. Tibia ash and tibia length were increased by supplementation of GCB (P ≤ 0.001). Tibia calcium and phosphorus content were increased by GCB inclusion at 14 d of age (P ≤ 0.001). Digestive alkaline phosphatase activity was increased and trypsin activity was reduced by inclusion of GCB (P ≤ 0.001; P ≤ 0.004). α-amylase activity decreased by inclusion of 12 and 24 g/kg GCB, whereas an increase in α-amylase activity was observed by inclusion of 36 g/kg GCB (P ≤ 0.001). Supplementation of diets with GCB increased phosphorus digestibility (P ≤ 0.01) and suppressed ileum growth during the experimental period. 4. Results of the current study showed that phosphorus from gelatin can greatly improve broiler bone characteristics and phosphorus digestibility and complete elimination of inorganic phosphate sources from broiler diets is feasible with inclusion of 36 g/kg high phosphorus gelatin.

Replacing soybean meal with gelatin extracted from cow skin and corn protein concentrate as a protein source in broiler diets.

Two experiments were conducted to investigate the effects of replacing soybean meal with gelatin extracted from cow skin and corn protein concentrate as a protein source in broiler diets. Experiments were carried out as a completely randomized design where each experiment involved 4 treatments of 6 replicates and 10 chicks in each pen. Soybean meal proteins in a corn-soy control diet were replaced with 15, 30, and 45% of cow skin gelatin (CSG) or corn protein concentrate (CPC), respectively, in experiments 1 and 2. BW and cumulative feed intake were measured at 7, 21, and 42 d of age. Blood characteristics, relative organs weight and length, ileal digesta viscosity, ileal morphology, and cecal coliform and Salmonella population were measured at 42 d of age. Apparent total tract digestibility of protein was determined during 35 to 42 d of age. Replacement of soybean meal with CSG severely inhibited BW gain, decreased feed intake, and increased FCR in broilers during the experimental period (P ≤ 0.01). The inclusion of CPC reduced BW and increased FCR significantly (P ≤ 0.05) at 21 and 42 d of age without any consequence in feed intake. Protein digestibility was reduced and ileal digesta viscosity was increased linearly by increasing the amount of CSG and CPC in the control diet (P ≤ 0.01). Replacement of soybean meal with CSG and CPC did not significantly alter blood cell profile and plasma phosphorus, creatinine, blood urea nitrogen, Aspartate transaminase, and HDL and LDL cholesterol concentration. The inclusion of CSG linearly (P ≤ 0.05) increased plasma uric acid concentration and alkaline phosphatase activity. Triglyceride and cholesterol levels were decreased significantly (P ≤ 0.05) when the amount of CSG replacement was 15%. The results of this experiment showed that using CSG and CPC negatively affects broiler performance and therefore is not a suitable alternative to soybean meal in commercial diets.

Effectiveness of Phytogenic Feed Additive as Alternative to Bacitracin Methylene Disalicylate on Hematological Parameters, Intestinal Histomorphology and Microbial Population and Production Performance of Japanese Quails.

This study was conducted to evaluate the effects of phytogenic additive and antibiotic growth promoter in laying Japanese quails. One hundred and sixty five quails were divided into three groups of 5 replicates and 11 quails (8 females and 3 males) in each replicate. Treatment 1 was fed control diet, treatment 2 was fed control diet supplemented with 0.05% bacitracin methylene disalicylate as antibiotic growth promoter and treatment 3 was fed control diet supplemented with 0.1% phytogenic feed additive (PFA) for two periods of 3 weeks each from 37 to 42 weeks of age. Results showed that egg production, eggshell strength, eggshell weight, villus height and villus height to crypt depth ratio were significantly (p≤0.05) increased and feed consumption, feed conversion ratio, albumen, Haugh unit, cholesterol, low-density lipoprotein, alanine transaminase, gamma glutamyltransferase, alkaline phosphatase, high-density lipoprotein, triglyceride, number of goblet cell, crypt depth and intestinal bacterial population of Coliforms, Salmonella and E. coli were significantly (p≤0.05) decreased in PFA fed group. It is concluded that addition of PFA containing phytomolecules and organic acids as main ingredients could significantly improve the production parameters and the general health of laying quails as an alternative to antibiotic growth promoters.

Experimental pathology of T-2 toxicosis and mycoplasma infection on performance and hepatic functions of broiler chickens.

This experiment was conducted using 192 day-old Ross 308 chicks, divided into 4 groups of 4 replicate consisting 48 birds. Group I was fed a control diet, Group II was fed control diet supplemented with 0.5 ppm T-2 toxin for 5 weeks, Group III was fed control diet supplemented with 8 × 10(8) cfu/mL of Mycoplasma gallisepticum, and group IV was fed control diet supplemented by T-2 toxin and Mycoplasma gallisepticum. Body weight and feed conversation ratio (FCR), relative organ weights, clinical signs, biochemical characteristics, and gross and histopathological lesions were recorded in the experimental groups at the end of the second and fifth weeks of age. Body weight and relative weights of bursa of Fabricius, thymus, and spleen decreased and FCR increased significantly (P ≤ 0.05), but the relative weights of liver and kidney showed no significant decrease (P ≤ 0.05) in the serum total proteins, albumin, and increase in aspartate aminotransferase and alanine transaminase were observed in T-2 toxin and T-2 accompanied with Mycoplasma fed birds when compared to the control group. Liver was enlarged, friable, and yellowish discoloration with distended gall bladder was noticed. Lymphoid organs such as bursa of Fabricius, thymus, and spleen were atrophied in group II and group IV throughout the study. Microscopically, liver showed vacuolar degeneration of hepatocytes, with increased Kupffer cell activity, bile duct epithelial hyperplasia, and infiltration of inflammatory cells. Kidney showed vacuolar degeneration of tubular epithelium along with pyknotic nuclei. Lymphoid organs showed lymphocytolysis and depletion with prominent reticuloepithelial cells. Proventriculus revealed desquamation of villous epithelial cells and lymphoid infiltration in submucosa. Heart showed mild hemorrhage with infiltration of inflammatory cells. Lung showed edema and inflammatory cells in the bronchioles. Trachea showed desquamation and erosions of mucosa. Proliferation of mucosal glands with increased mucous secretion was obvious. Air sacs showed thickening with presence of inflammatory cells and edema.

Effect of pulmonary surfactant on antimicrobial activity in vitro.

Time-kill curve experiments were performed with linezolid, doripenem, tigecycline, moxifloxacin, and daptomycin against Staphylococcus aureus and with colistin, moxifloxacin, and doripenem against Pseudomonas aeruginosa to evaluate the effect of porcine pulmonary surfactant on antimicrobial activity. Pulmonary surfactant significantly impaired the activities of moxifloxacin and colistin. When antibiotics are being developed for respiratory tract infections, the method described here might be used to preliminarily quantify the effect of pulmonary surfactant on antimicrobial activity.

An initial safety assessment of hepatotoxic and nephrotoxic potential of intramuscular ketoprofen at single repetitive dose level in broiler chickens.

A study was undertaken to assess the hepatotoxic and nephrotoxic potential of ketoprofen in comparison with diclofenac upon short-term intramuscular (i.m.) administration in broiler chickens. Eighteen broiler chickens were randomly divided into 3 groups of 6 birds each. Group I served as the control and received normal saline (0.1 mL, i.m.), group II was the positive control and received diclofenac sodium (2.5 mg/kg, i.m.), and group III received ketoprofen (3 mg/kg, i.m.) daily at 24-h intervals for 5 consecutive days. Diclofenac sodium-treated birds showed severe clinical signs of toxicity with high mortality, a significant increase (P < 0.01) in serum concentrations of creatinine, uric acid, alanine aminotransferase, and aspartate aminotransferase, and these changes correlated well with gross and microscopic examination findings of kidney and liver. In contrast, ketoprofen-treated birds did not show any adverse clinical signs and no significant increase in concentration of creatinine, uric acid, alanine aminotransferase, and aspartate aminotransferase when compared with birds in group I. Gross and microscopic examination of kidney and liver showed normal organ architecture. Thus, based on the present findings, it was concluded that ketoprofen at the dose of 3 mg/kg administered intramuscularly daily for 5 d was nontoxic to broiler chickens.

Plasma protein binding may reduce antimicrobial activity by preventing intra-bacterial uptake of antibiotics, for example clindamycin.

OBJECTIVES: although plasma protein binding (PPB) is accepted to be an essential factor in reducing antimicrobial activity, little is known about the underlying mechanisms. One possibility includes impaired penetration of an antimicrobial into bacterial cells in the presence of PPB. As a prerequisite for testing this hypothesis an optimized medium displaying high protein binding without impairing bacterial growth had to be identified for our model compound clindamycin. METHODS: determination of PPB, bacterial growth and antimicrobial killing was performed in Mueller-Hinton broth (MHB) containing various amounts of human albumin or serum. [(3)H]clindamycin was used to investigate clindamycin penetration into Staphylococcus aureus. RESULTS: of all investigated media only MHB(50%serum) and MHB(70%serum) achieved protein binding comparable to pure serum. In contrast, MHB(20%serum) and most media containing only albumin demonstrated considerably lower protein binding. Pure serum resulted in bacterial growth inhibition compared with MHB while MHB(16%albumin) and MHB(50%serum) did not result in significant differences in bacterial count after 24 h. However, in both MHB(16%albumin) and MHB(50%serum) the antimicrobial activity of clindamycin was reduced by >2 log(10) cfu/mL compared with pure MHB. The radioactive signal after administration of [(3)H]clindamycin to S. aureus was significantly decreased in pure serum as well as in MHB(16%albumin) and MHB(50%serum), while no significant difference was observed for MHB(4%albumin) and MHB(20%serum). CONCLUSIONS: reduction of the intracellular radioactive signal in the presence of serum proteins correlated both with the degree of protein binding and reduction of antimicrobial activity supporting the hypothesis of impairment of activity by PPB by reducing intra-bacterial antimicrobial concentrations.

Antimicrobial effect of statins: organic solvents might falsify microbiological testing results.

OBJECTIVES: Statins possess a variety of pleiotropic effects. Direct antimicrobial effect of simvastatin and, to a smaller degree, fluvastatin, has been reported for Gram-positive bacteria. The present study investigated antimicrobial activity of all statins available on the European market on Gram-positive and -negative organisms, with particular attention on the possible impact of organic solvents on bacterial growth. METHODS: Simvastatin was dissolved both in 100% methanol (simvastatin 100%) and in 5% methanol (simvastatin 5%), the latter solution requiring pH adjustment for solubility reasons. Antimicrobial activity of both simvastatin solutions and of five other statins was evaluated against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 by broth microdilution testing. In addition, time-kill curves of methanol alone, simvastatin 100% and simvastatin 5% were performed for S. aureus ATCC 29213. RESULTS: Relevant antimicrobial activity was observed only for simvastatin 100% when tested against S. aureus (MIC = 31 mg/l). MIC of simvastatin 5% was more than 10-fold higher (500 mg/l). In analogy, time-kill rates of simvastatin against S. aureus decreased markedly when the methanol content in the test solutions was reduced. In both experimental settings, antimicrobial activity observed for pure methanol was only slightly inferior to that of simvastatin 100%. CONCLUSION: Previously published results about the antimicrobial effect of statins relied on the use of pure methanol as solvent. Present data indicate that the observed antimicrobial effect must be attributed, at least to a very large extent, to the solvent. Toxicity of solvents may influence microbiological evaluation of poorly water-soluble substances. pH adjustment to enhance solubility and thus reduce the need for using organic solvent might sometimes overcome this problem.

Efficacy of Bacillus subtilis and bacitracin methylene disalicylate on growth performance, digestibility, blood metabolites, immunity, and intestinal microbiota after intramuscular inoculation with Escherichia coli in broilers.

This experiment was conducted to evaluate the effect of Bacillus subtilis (BS) on broiler performance and health after intramuscular inoculation with E. coli and compare its effect with a growth promoter antibiotic. In a completely randomized design manner, 360 male Ross 308 chicks were divided into 6 treatments and 5 replicates of 12 chicks in each replicate. Experimental treatments included control diet, control + E. coli (0.5 mL of culture containing 108 CFU of E. coli/ml), control + 0.1% BS, control + 0.05% bacitracin methylene disalicylate (BMD), control + E. coli and BS, and control + E. coli and BMD in a factorial arrangement (3 × 2). Addition of BMD or BS to the control diet significantly (P < 0.01) increased body weight and decreased FCR, but E. coli challenge adversely reduced (P < 0.01) body weight and increased FCR, so that the addition of BMD or BS did not compensate growth reduction. E. coli challenged chicks had the lowest vaccine titers for ND, IB, AI, and IBD and the highest were observed in chicks fed BS. The E. coli challenge significantly (P < 0.01) increased albumin, globulin, cholesterol, triglyceride, LDL, ALT, and ALP indices. Addition of BMD and BS decreased albumin and globulin in challenged chick's plasma but had no effect on plasma lipid profile concentration. The E. coli challenge decreased villus height and increased crypt depth and goblet cell numbers significantly (P < 0.01). In birds subjected to BMD or BS, crypt depth decreased and villus height increased (P < 0.01), compared with the control diet. Challenge of E. coli significantly (P < 0.01) increased the bacterial population of E. coli, coliforms, and Salmonella in cecal parts of broilers' intestines. In challenged birds receiving BMD or BS, E. coli, coliform, and Salmonella populations of ceca showed a significant (P < 0.01) reduction. Both BMD and BS increased the digestibility of nutrients significantly (P < 0.01), but a reduction was observed in E. coli challenged groups. Results of the study suggest that spore-forming probiotics are partially effective in unsuitable rearing situations such as colibacillosis in which the load of harmful bacteria is high.

Synthesis of nanocomposites from polyacrylamide and graphene oxide: Application as flocculants for water purification.

Polyacrylamide/graphene (PAM/GO) based nanocomposites were synthesized and applied as flocculating agent for cleansing the solvent phase. In order to obtain the better dispersion of the graphene nanoplatelets in matrix the functionalization was carried out using acid and upon analytical characterization the successful fine dispersion of FGNp was found in the PAM matrix. The influence of GO concentrations on viscosity, charge demand, flocculating and dewatering with ambient micrometer-sized ground calcium carbonate (GCC) was well evaluated and elucidated. It was found that on increasing the GO content in the PAM/GO nanocomposites, the filtered weight of GCC suspensions also increases, and the filtrate turbidity decreased and it was also observed that on adding the GO both η and supernatant turbidity reduced: by growing GO concentrations, there was a fall in η and turbidity of cleaned water. The retention mechanism proceeds through a parallel method to microparticle retention system which is done via bridge/patch among pulp and filler.

Broiler chicks with slow-feathering (K) or rapid-feathering (k+) genes: Effects of environmental stressors on physiological adaptive indicators up to 56 h posthatch.

Two experiments were conducted to examine the effects on the physiological responses of slow-feathering (K) and rapid-feathering (k(+)) genes in neonate broiler chicks subjected to posthatch fasting (PHF). In the first experiment, 300 Ross 308 chicks were denied access to feed and water for 0, 7, 14, 21, 28, 35, 42, 49, and 56 h posthatch. In the second experiment, 625 Ross 308 chicks were subjected to PHF for 0, 12, 24, 36, and 48 h. In experiment 1, the weight loss rate increased over 56 h PHF and did not differ between fast- and slow-feathering chicks up to 28 h posthatch but was greater (P < 0.05) in fast-feathering birds from 28 to 56 h posthatch. The fast-feathering genotypes demonstrated greater serum K levels following 7, 21, and 56 h (P < 0.05) and serum uric acid (UA) levels after 7, 21, 28, 49, and 56 h PHF (P < 0.01). In experiment 2, weight loss increased linearly with no difference between fast- and slow-feathering chicks through 36 h PHF but increased in fast-feathering birds when PHF continued for 48 h. Neonatal fasting periods of 12 to 48 h decreased breast and thigh percentage (P < 0.01), with no difference between feathering genotypes. The fast-feathering genotypes showed greater serum HDL levels at 24 h (P < 0.05) and greater serum UA concentration following 12, 36, and 48 h PHF (P < 0.05). The mean frequency of jumping (P < 0.01) and active wakefulness (P > 0.01) was increased as PHF continued from 12 to 48 h across genotypes. At 48 h, the fast-feathering chicks showed greater frequency of escape attempts from the test field (P < 0.01). It was concluded that slow-feathering chicks are more capable of withstanding PHF periods lasting more than 28 h. This is important to consider when day-old chicks are transported for extended periods without access to feed.

New developments in chromogenic and fluorogenic culture media.

This review describes some recent developments in chromogenic and fluorogenic culture media in microbiological diagnostic. The detection of beta-D-glucuronidase (GUD) activity for enumeration of Escherichia coli is well known. E. coli O157:H7 strains are usually GUD-negative and do not ferment sorbitol. These characteristics are used in selective media for these organisms and new chromogenic media are available. Some of the new chromogenic media make the Salmonella diagnostic easier and faster. The use of chromogenic and fluorogenic substrates for detection of beta-D-glucosidase (beta-GLU) activity to differentiate enterococci has received considerable attention and new media are described. Rapid detection of Clostridium perfringens, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus are other application of enzyme detection methods in food and water microbiology.

Fluorogenic and chromogenic enzyme substrates in culture media and identification tests.

Rapid detection and identification of microorganisms is extremely important in many fields of applied and research microbiology. In general, fluorogenic and chromogenic substrates have proved to be a powerful tool, utilizing specific enzymatic activities of certain microorganisms, either in parallel with or instead of traditional methods. By incorporation of synthetic fluorogenic or chromogenic substrates into primary selective media, enumeration and detection can be performed directly on the isolation plate. The introduction of many of these media and identification tests has led to improved accuracy and faster detection of target organisms, often reducing the need for isolation of pure cultures and confirmatory tests.

Comparative evaluation of different chromogenic/fluorogenic media for detecting Escherichia coli O157:H7 in food.

Escherichia coli O157:H7 is a serious and common human pathogen that can cause diarrhoea, haemorrhagic colitis, and haemolytic uraemic syndrome (HUS). This study evaluated the enrichment, detection and confirmation procedures for the isolation of E. coli O157:H7 from raw ground beef and raw drinking milk. The purpose of this investigation was to compare Rainbow Agar O157 (RB; Biolog, Hayward, USA), Biosynth Culture Medium O157:H7 (BCM O157:H7; Biosynth, Staad, Switzerland) and Fluorocult HC (HC; Merck, Darmstadt, Germany) with the conventional Sorbitol MacConkey Agar (SMAC, Merck) using mEC + n (raw ground beef) and mTSB + n (raw milk) enrichment media. Single-path GLISA test (Gold Labeled Immuno Sorbent Assay; Merck) was used as the confirmation test. Growth of 466 strains of gram-negative rods isolated from food samples and 46 known E. coli strains from type culture and other collections (34 E. coli O157:H7 strains and 12 serotypes other than E. coli O157:H7) was examined on the agar media. The E. coli O157:H7 strains could readily be isolated and recognized uniquely by their typical black/grey colonies on RB and blue/black colonies on BCM O157:H7. Examination of the 46 known strains of E. coli reference strains showed false negative results on BCM O157:H7 (3.0%), RB (8.8%), HC (5.9%) and SMAC (5.9%) agars. On BCM O157:H7 no false negative results were found with the typical E. coli O157:H7 (beta-D-glucuronidase and sorbitol negative strains). One of two atypical E. coli O157:H7 strains (beta-D-glucuronidase positive) showed similar colouration to the typical strains and was mis-identified by each of the three media (RB, BCM O157:H7, and SMAC agar media). None of the 60 food samples tested yielded E. coli O157:H7. Examination of the food samples, showed that RB gave the lowest number of false positives. The percentages were RB (2.1%), BCM O157:H7 (3.3%), HC (6.2%), and SMAC (57.3%).

A new plate medium for rapid presumptive identification and differentiation of Enterobacteriaceae.

A new selective differential agar medium for rapid presumptive identification of Enterobacteriaceae from water and food samples is described (EMX ID agar). By a combination of fluorogenic and chromogenic substrates, the medium detects the presence of beta-D-glucuronidase, beta-D-galactosidase, beta-D-xylosidase, tryptophane deaminase and H2S; additionally, cytochrome-oxidase and indole production can be demonstrated. This medium provides an inexpensive means for simple and rapid presumptive identification of E. coli and coliforms and for the differentiation within the Klebsiella-Enterobacter and the Proteus-Providencia-Morganella group. Furthermore, it allows to distinguish between the H2S-positive Enterobacteriaceae Citrobacter freundii, Salmonella spp., S. arizonae, Edwardsiella, Proteus mirabilis, P. vulgaris and some oxidase-positive bacteria.

Comparison of the Vitek, API 20E and Gene-trak® systems for the identification of Yersinia enterocolitica.

The current improvements in nucleic acid hybridization technology provide new techniques for the identification of micro-organisms. One such technique is the Gene-trak® DNA hybridization system (Framingham, MA, USA), which was introduced in 1983. The objective for this study was to evaluate the new Gene-trak®Yersinia enterocolitica kit in comparison with the API 20E and Vitek systems. A total of 101 strains including 18 reference non-Yersinia strains from the authors' stock culture collection and 83 suspected positive isolates from CIN agar were tested. Of these 83 isolates, 40 were identified as Y. enterocolitica after incubation at 37°C for 24 with the API 20E system; 37 strains were identified at 30°C for 48 h. The Gene-trak® method gave positive results with 39 strains. The Vitek system gave positive results with 27 strains. With the Gene-trak® method, Y. enterocolitica was detectable in mixed cultures provided that the numbers of cfu ml-1 were equal to or above 106 Y. enterocolitica ml-1 . Although enrichment procedures are still needed, the system provides a quick detection of these food-borne pathogens.

Rapid methods for differentiating gram-positive from gram-negative aerobic and facultative anaerobic bacteria.

Different tests based on lysis by KOH and on reaction with fluorogenic and chromogenic substrates, L-alanine-4-nitroanilide (LANA); L-alanine-4-methoxy- beta-naphthylamide (MNA); 4-alanine-2-amidoacridone (AAA); L-alanine-7-amido- 4-methylcoumarin (AAMC); 8-anilino-1-naphthalene-sulphonic acid (ANS) were compared for their suitability to distinguish Gram-positive from Gram-negative bacteria. A concentration of 100 micrograms/ml was chosen for incorporating LANA, AAA, AAMC and ANS into the growth medium, based on sensitivity tests. MNA did not show any detectable reaction over a concentration range from 50 to 200 micrograms/ml, and led to inhibition of all bacteria at 200 micrograms/ml. In the examination of a total of 146 bacterial strains, including Yersinia enterocolitica, Bacillus cereus, and B. subtilis the KOH test was not comparable with the Gram staining. A good correlation with Gram staining was found between LANA, AAA and AAMC added to plate count agar on one hand, and LANA and AAMC impregnated paper strips on the other hand, thereby utilizing the aminopeptidase activity. Agar containing ANS showed detectable fluorescence with all Gram-negative strains, but with Staphylococcus aureus and Staph. epidermidis a weak reaction was also observed. AAMC was selected for a rapid paper strip test. With this substrate a pronounced blue fluorescence was obtained with Gram-negative colonies.

[A combined chromogenic-fluorogenic medium for the simultaneous detection of coliform groups and E. coli in water]. / Ein kombiniertes Chromogen-Fluorogen-Medium zum simultanen Nachweis der Coliformengruppe und von E. coli in Wasser.

A comparison was made with different chromogenic and fluorogenic substrates, 4-methylumbelliferyl-beta-D-glucuronide (MUG), 4-nitrophenyl-beta-D-glucuronide (PNPG), 4-methylumbelliferyl-beta-D-galactopyranoside (MUGA), 2-nitrophenyl-beta-D-galactopyranoside (ONPG), 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-GAL), for the rapid and simultaneous enumeration of total coliforms and E. coli in water samples, based on 2 commercially available culture-media. The combination of the chromogenic compound X-GAL (for detecting coliforms) and of the fluorogenic compound MUG (for detecting E. coli) incorporated either into ECD agar or into lauryl sulfate broth proved to be most useful. The optimum concentration of the X-GAL/MUG supplement was (50 micrograms/ml/70 micrograms/ml) for the solid medium (EMX agar) and (60 micrograms/ml/70 micrograms/ml) for the fluid medium (LMX broth). As a result of the examination of 244 Enterobacteriaceae strains isolated from water samples and clinical material, it was shown that the use of EMX agar (LMX broth) had several advantages over conventional methods. A routine method for the analysis of water samples was proposed involving the EMX agar and the LMX broth.

Fluorogenic and chromogenic substrates--a promising tool in microbiology.

During the last few years the use of fluorogenic and chromogenic substrates for rapid and sensitive detection of bacteria has proved to be a powerful alternative to traditional methods. These sophisticated substrates might find widespread application in, for instance, the assay of clinically important enzymes, flow cytometry, and direct epifluorescent filter technique. Specific enzyme detection offers another approach to differential identification and characterization of viable bacteria from a sample. The use of some chromogenic and fluorogenic substrates specific for bacterial enzymes and their applications to microbial identification is reported. Particular emphasis is given to the examination of Escherichia coli and the description of the different techniques as used in routine analysis.

Evaluation of a new chromogenic agar medium for the identification of urinary tract pathogens.

This study evaluated the performance of CPS ID2 (bioMérieux) compared to that of conventionally used selective agar for the identification of bacteria responsible for urinary tract infections. This medium detects bacterial enzymes using chromogenic substrates. Two hundred and nineteen samples of urine were tested in order to evaluate new CPS ID2 in comparison to blood agar and MacConkey agar. According to our results, the CPS ID2 agar is an easy, rapid and sensitive method for the screening of colonies suspected of being Escherichia coli, reducing the number of biochemical tests needed. Also, enterococci and Proteae can be easily detected. Other micro-organisms require further identification. The greatest value of this medium is the accurate identification of polymicrobial cultures.