Reduction Of Viable Bacteria Research Articles

Vancomycin Bactericidal Activity as a Predictor of 30-Day Mortality in Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia

Vancomycin has been the drug of choice for the treatment of serious methicillin-resistant Staphylococcus aureus (MRSA) infections for over 5 decades. It demonstrates slower bactericidal activity in comparison to the results seen with antistaphylococcal beta-lactams against S. aureus (1). Moise et al. showed that 30-day mortality was related to the in vitro bactericidal activity of vancomycin (3). This study sought to determine whether the in vitro bactericidal activity of vancomycin, as well as other MRSA strain-specific characteristics, such as a polymorphism at accessory gene regulator (agr) locus (4, 5) and vancomycin MIC (2, 7), impacts the mortality associated with MRSA bacteremia. A total of 129 consecutive MRSA blood isolates recovered from patients with MRSA bacteremia admitted to the First Department of Internal Medicine (52 beds) and Emergency Medical Care Center (32 beds), Fukuoka University Hospital, from 1991 through 2004 were identified. This study focused on 66 isolates recovered from the 66 patients initially treated with glycopeptides (vancomycin [n = 42 patients] or teicoplanin [n = 24 patients]) after the onset of bacteremia. Bactericidal assays were performed over 72 h as reported by Sakoulas et al., using a concentration of 16 μg/ml against MRSA at an initial inoculum of approximately 108 CFU/ml (6). The clinical data were extracted from patients' medical records, and mortality that occurred within 30 days after the onset of bacteremia was examined. The in vitro bactericidal activity of vancomycin showed high heterogeneity among the isolates, with reduction in viable bacteria at 72 h ranging from 2.5 log10 to 7.2 log10 CFU/ml. The median (interquartile range) bactericidal activity was 4.4 (3.8 to 5.4) log10 CFU/ml. Overall, 26 (39.4%) of the 66 patients died during the first 30 days after the onset of MRSA bacteremia. There was no difference in the 30-day mortality between the patients treated with vancomycin and those treated with teicoplanin (42.9% versus 33.3%, P = 0.45). Univariate analysis indicated a statistically significant relationship between mortality and the in vitro bactericidal activity of vancomycin (P = 0.017), renal failure indicated by the necessity for dialysis (P = 0.025), the Acute Physiological and Chronic Health Evaluation II (APACHE II) score (P = 0.007), and the presence of shock (P = 0.005), while agr group (P = 0.36), agr function (P = 0.07), and vancomycin MIC (P = 0.13) were not significant. Multivariate logistic regression analysis with forward stepping on mortality using independent variables, with a P value of <0.2 in the univariate analysis, showed that decreased in vitro bactericidal activity of vancomycin (odds ratio [OR], 2.04; P = 0.021), APACHE II score (OR, 1.16; P = 0.018), and the presence of shock (OR, 6.56; P = 0.025) were predictors of mortality. In addition, a Hill-type mathematical model (Fig. ​(Fig.1)1) identified a very close relationship between vancomycin bactericidal activity and mortality in patients with MRSA bacteremia (R2 = 0.983), with a 3.8-log reduction in bacteria necessary to achieve a 50% probability of survival. FIG. 1. Vancomycin pharmacodynamics showing the relationship between the probability of survival and bactericidal activity, which was fit to a Hill-type mathematical model (R2 = 0.983). The probability of survival based on the 30-day mortality data for ... Although previous studies have examined the relationship of vancomycin killing activity and treatment failure (3, 6), this current study is the first to demonstrate a relationship with attenuated vancomycin bacterial killing and an increased probability of mortality in the multivariate analysis. In addition, the attenuated vancomycin bactericidal activity was more frequently observed in isolates from endovascular sources than in other sources (P = 0.043). This result demonstrates that reduced vancomycin killing in vitro could therefore be a surrogate marker of high-risk sources of bacteremia. Although performing vancomycin bactericidal assays over 72 h may be too labor-intensive to successfully implement in clinical microbiological analyses, this study highlights the potential problems associated with suboptimal vancomycin killing. These findings suggest that the evaluation of this characteristic may therefore be useful through other phenotypic markers of tolerance, such as those measured by minimal bactericidal concentration (MBC)/MIC and serum bactericidal assays, when considering antimicrobial therapies that can be used as alternatives to either vancomycin or teicoplanin for the treatment of MRSA bacteremia.

The Antimicrobial Activity of an Atmospheric-Pressure Room-Temperature Plasma in a Simulated Root-Canal Model Infected With Enterococcus Faecalis

The antimicrobial activity of an atmospheric-pressure room-temperature plasma jet on simulated root canals infected with Enterococcus faecalis is studied. The samples are divided randomly into 12 experimental groups and one control group. All experimental groups exhibited a significant reduction in viable bacteria compared with the control group ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <; 0.01 ). The largest reductions were obtained in Group 9 (with plasma jet containing 5.25% sodium hypochlorite sterilization for 12 min after irrigating the root canals with 1-ml sterile physiologic saline) and Group 12 (with plasma-jet sterilization for 12 min after irrigating the root canals with 1-ml sterile physiologic saline), with 6.21 and 5.62 log reductions, respectively. It is concluded that plasma jet containing 5.25% sodium hypochlorite as well as plasma jet only can effectively sterilize the simulated root canals.

Addition of gentamicin to endoscopic retrograde cholangiopancreatography (ERCP) contrast medium towards reducing the frequency of septic complications of ERCP

Bacteremia and sepsis are serious complications of endoscopic retrograde cholangiopancreatography (ERCP) and occur in between 0.5 and 3% of cases. Patients with obstructed bile ducts are at highest risk of developing septic complications. The purpose of this investigation was to determine whether the addition of gentamicin to the ERCP contrast medium prevents or reduces the growth of Pseudomonas aeruginosa in vitro. Artificial bile ducts were fashioned out of dialysis tubing and suspended in flasks containing brain heart infusion (BHI) broth. The tubing contained BHI broth alone, with or without contrast medium or with contrast medium plus gentamicin. The artificial ducts were inoculated with gentamicin-sensitive or gentamicin-resistant P. aeruginosa and quantitative cultures were performed. The contrast medium alone was bacteriostatic to both sensitive and resistant P. aeruginosa isolates. The addition of gentamicin to the contrast medium eliminated the sensitive strain after 2 h and resulted in a reduction in the number of gentamicin-resistant P. aeruginosa after 4 h. Incubation of the resistant isolate in the presence of contrast and gentamicin for an additional 4 h led to a further reduction in viable bacteria but did not completely eliminate the organisms. These results support the use of gentamicin in the contrast medium injected into the biliary system as an ancillary method to prevent post-ERCP sepsis.

Antimicrobial activity of the green tea polyphenol (−)-epigallocatechin-3-gallate (EGCG) against clinical isolates of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is increasingly recognised as an important nosocomial pathogen. Treatment options are limited due to intrinsic resistance to many antibiotics as well as concerns over toxicity of the mainstay of treatment, co-trimoxazole. Epigallocatechin-3-gallate (EGCG), the major catechin found in green tea, has been shown to have antimicrobial effects against a number of bacterial pathogens. We evaluated the in vitro activity of this compound against 40 clinical isolates of S. maltophilia. MIC 50/90 values (minimal inhibitory concentrations for 50% and 90% of the organisms, respectively) were 256 mg/L when determined by agar dilution and 512 mg/L by broth microdilution. MBC 50/90 values (minimal bactericidal concentrations for 50% and 90% of the organisms, respectively) were 512 mg/L. In time–kill assays, the bactericidal activity of EGCG was analysed by viable colony counts as well as a colorimetric assay for bacterial reduction of XTT. EGCG was slowly bactericidal at 4× MIC, with a 2.5 log reduction in viable bacteria at 24 h. EGCG has promising in vitro antimicrobial activity against S. maltophilia. Although the mechanism of action is not yet clear, further studies to evaluate its clinical potential and role in combination with other antimicrobial agents are warranted.

A Multilevel Antimicrobial Coating Based on Polymer-Encapsulated ClO2

A multilevel antimicrobial coating with "release-killing", "contact-killing" and "anti-adhesion" properties was prepared from polymer-encapsulated chlorine dioxide (ClO(2)), water-in-oil-in-water (w/o/w) double emulsion. A slow sustained release of gaseous ClO(2) at a rate sufficient to inhibit bacterial growth (approximately 1300 microg of ClO(2).g(-1).day(-1)) was demonstrated for a prolonged period of time (i.e., 28 days). Touch and infectious droplets triggered an increased release of the biocides at the sites of contamination, resulting in rapid disinfection. Zinc chloride (i.e., 30 ppm) was added to provide "contact-killing" properties, while bacterial adhesion was prevented by the Pluronic polymer used to encapsulate ClO(2). The new antimicrobial coating is effective against Gram positive and Gram negative bacteria, including Bacillus subtilis , Staphylococcus aureus , and Escherichia coli. A greater than 5 log (i.e., >or= 99.999%) reduction of viable bacteria was obtained at a short contact time of 10 min.

Antimicrobial activity of methylene blue and toluidine blue O covalently bound to a modified silicone polymer surface

Methylene Blue or Toluidine Blue O were covalently bound to an activated silicone polymer by means of an amide condensation reaction. UV-visible absorption spectra confirmed that the dye was surface bound. The new polymers with covalently attached dye display significant bactericidal activity against Escherichia coli and Staphylococcus epidermidis with a 99.999% reduction in viable bacteria after four minutes exposure to a low power laser.

A novel cationic-peptide coating for the prevention of microbial colonization on contact lenses

To develop an antimicrobial peptide with broad spectrum activity against bacteria implicated in biomaterial infection of low toxicity to mammalian cells and retaining its antimicrobial activity when covalently bound to a biomaterial surface. A synthetic peptide (melimine) was produced by combining portions of the antimicrobial cationic peptides mellitin and protamine. In contrast to the parent peptide melittin which lysed sheep red blood cells at >10 microg ml(-1), melimine lysed sheep red blood cells only at concentrations >2500 microg ml(-1), well above bactericidal concentrations. Additionally, melimine was found to be stable to heat sterilization. Evaluation by electron microscopy showed that exposure of both Pseudomonas aeruginosa and Staphylococcus aureus to melimine at the minimal inhibitory concentration (MIC) produced changes in the structure of the bacterial membranes. Further, repeated passage of these bacteria in sub-MIC concentrations of melimine did not result in an increase in the MIC. Melimine was tested for its ability to reduce bacterial adhesion to contact lenses when adsorbed or covalently attached. Approximately 80% reduction in viable bacteria was seen against both P. aeruginosa and S. aureus for 500 microg per lens adsorbed melimine. Covalently linked melimine (18 +/- 4 microg per lens) showed >70% reduction of these bacteria to the lens. We have designed and tested a synthetic peptide melimine incorporating active regions of protamine and mellitin which may represent a good candidate for development as an antimicrobial coating for biomaterials. Infection associated with the use of biomaterials remains a major barrier to the long-term use of medical devices. The antimicrobial peptide melimine is an excellent candidate for development as an antimicrobial coating for such devices.

Mathematical Models of Cobalt and Iron Ions Catalyzed Microwave Bacterial Deactivation

Time differences for Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli survival during microwave irradiation (power 130 W) in the presence of aqueous cobalt and iron ions were investigated. Measured dependencies had "bell" shape forms with maximum bacterial viability between 1 - 2 min becoming insignificant at 3 minutes. The deactivation time for E. faecalis, S. aureus and E.coli in the presence of metal ions were smaller compared to a water control (4 -5 min). Although various sensitivities to the metal ions were observed, S. aureus and E. coli and were the most sensitive for cobalt and iron, respectively. The rapid reduction of viable bacteria during microwave treatment in the presence of metal ions could be explained by increased metal ion penetration into bacteria. Additionally, microwave irradiation may have increased the kinetic energy of the metal ions resulting in lower survival rates. The proposed mathematical model for microwave heating took into account the "growth" and "death" factors of the bacteria, forming second degree polynomial functions. Good relationships were found between the proposed mathematical models and the experimental data for bacterial deactivation (coefficient of correlation 0.91 - 0.99).

Structure–antimicrobial activity relationship for silanols, a new class of disinfectants, compared with alcohols and phenols

Triorganosilanols (R(CH 3) 2SiOH) were recently reported to exhibit unexpectedly strong disinfectant properties. The antimicrobial activities of silanols were significantly higher than their analogous alcohols. A study of the structural dependence of their antimicrobial activity was conducted against four bacteria, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis. Silanols, alcohols with structures analogous to the silanols (R(CH 3) 2COH) and substituted phenols were evaluated as a single class of materials. The minimum lethal concentrations (MLCs), defined as the concentration required for a 7-log reduction in viable bacteria after 1 h exposure, were used to measure antimicrobial activity. Octanol–water partition coefficients (log P) and hydrogen bond acidities (δν), measured as the shift in frequency of the OH stretching band between free OH and hydrogen-bonded OH to diethyl ether oxygen by infrared spectroscopy, were utilised as dispersive and polar structural parameters, respectively. The correlation established by multiple regression analysis between antimicrobial activities and structural properties of silanols, alcohols and phenols against the four bacteria treated as a single family produced the following equation, log(1/MLC) = 0.679 log P + 0.0036δν − 1.909 ( n = 282, r = 0.96, s = 0.22). This equation and the significantly high correlation coefficient supported the hypothesis that the lipophilic properties and the H-bond acidities are primary factors for the antimicrobial action of silanols, alcohols and phenols. The high antimicrobial activity of silanols is explained by their greater H-bond acidity and their enhanced lipophilicity.

Initiated chemical vapor deposition of antimicrobial polymer coatings

The vapor phase deposition of polymeric antimicrobial coatings is reported. Initiated chemical vapor deposition (iCVD), a solventless low-temperature process, is used to form thin films of polymers on fragile substrates. For this work, finished nylon fabric is coated by iCVD with no affect on the color or feel of the fabric. Infrared characterization confirms the polymer structure. Coatings of poly(dimethylaminomethyl styrene) of up to 540 μg/cm 2 were deposited on the fabric. The antimicrobial properties were tested using standard method ASTM E2149-01. A coating of 40 μg/cm 2 of fabric was found to be very effective against gram-negative Escherichia coli, with over a 99.99%, or 4 log, kill in just 2 min continuing to over a 99.9999%, or 6 log, reduction in viable bacteria in 60 min. A coating of 120 μg/cm 2 was most effective against the gram-positive Bacillus subtilis. Further tests confirmed that the iCVD polymer did not leach off the fabric.

Antibacterial Mechanism of Allyl Isothiocyanate

Allyl isothiocyanate (AITC), a natural compound in plants belonging to the family Cruciferae, has been shown to have strong antimicrobial activity in liquid media as well as in its vapor form. To understand its antimicrobial mechanism, AITC was tested for bactericidal activities to Salmonella Montevideo, Escherichia coli O157:H7, and Listeria monocytogenes Scott A at different stages of growth and was compared with streptomycin, penicillin G, and polymyxin B, each of known antibacterial mechanisms. Bactericidal activities were determined by measuring bacterial viability and leakage of metabolites. To determine its effects on membrane permeability, β-galactosidase activity was examined after exposure of E. coli K-12 strain 3.300 to the three antibiotics and to AITC. The two gram-negative bacteria, Salmonella Montevideo and E. coli O157:H7, were more sensitive to AITC and to polymyxin B than the gram-positive L. monocytogenes. AITC and polymyxin B were effective bactericidal agents to bacteria at all growth stages, whereas penicillin G and streptomycin did not exhibit bactericidal activity to stationary cells. High A260 and A280 values of cellular filtrate and β-galactosidase activity were obtained after treatments of AITC and polymyxin B. These data indicated that AITC was most similar to polymyxin B with respect to its antibacterial effect on cell membranes and on leakage of cellular metabolites. Gaseous AITC caused metabolite leakages, measurable increases in β-galactosidase activity, and reduction of viable bacteria. The effectiveness of AITC in inhibiting bacteria at all growth stages and its strong activity in vapor phase support its application in food preservation.

New cytokine dressings. II. Stimulation of oxidative burst in leucocytes in vitro and reduction of viable bacteria within an infected wound

Recently, we have developed the new dressings containing rhG-CSF or rhGM-CSF. In the present study we investigated either in vitro or in vivo biological activity of the dressings. Human whole blood samples were incubated with extracts from the collagen- or polyurethane-based dressings containing rhG-CSF or/and rhGM-CSF and phagocytic and oxidative metabolic activities were quantitated using Phagotest or Bursttest kits. The results indicate that both the number of phagocyting cells and the intensity of phagocytosis per cell, as well as the level of the oxidative burst in particular, were stimulated by one or both of the cytokines extracted. Next, the experimental skin wounds in mice were infected with 10 7 CFU of Pseudomonas aeruginosa strain ATCC 27853 and treated locally with the rhG-CSF-containing dressing. The analysis of the biopsies taken from the wounds indicated that in mice treated with the cytokine-containing dressing on the third day the log of CFU per biopsy was 5.0 vs. 6.2 in the control ( P<0.001), and on the 8th day was lower than 4 vs. 5.4 in control ( P<0.0001). Our findings clearly suggest that the newly designed dressings containing the incorporated CSFs can be used as effective topical cytokine-delivery system in the treatment of bacterial infections in wounds.

Effect of High Concentration of a Disinfectant Solution on Reduction of Viable Bacteria.

Effect of High Concentration of a Disinfectant Solution on Reduction of Viable Bacteria.

Effects of different surfactant preparations on bacterial growth in vitro.

Several lines of evidence suggest that surfactant and surfactant proteins may have direct effects on inhaled bacteria and are able to interact with lung defence mechanisms in many ways. We examined the effect of three different surfactant preparations (Alveofact, Survanta and Exosurf) approved for treatment of the infant respiratory distress syndrome on different strains of Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae which are important neonatal pathogens and on Legionella pneumophila serogroup I as a frequent cause of pneumonia in adults. Addition of Survanta to saline seemed to delay the reduction of viable bacteria in sterile saline and induced a considerably accelerated growth of all examined E. coli strains. As opposed to this, addition of surfactant did not influence the kinetics of bacterial growth in brain-heart infusion or buffered yeast extract both with the exception of Exosurf which exerted an inhibitory effect on the multiplication of group B streptococci. Though the exact mechanisms underlying these effects remain to be determined, the influence of surfactant therapy on the growth of bacteria within the respiratory tract should be taken into account.

Keratotomy Model of Pseudomonas Keratitis: Gentamicin Chemotherapy

Chemotherapy of bacterial keratitis requires frequent application of antibiotic drops. Collagen shields containing antibiotics could reduce the need for frequent antibiotic application. To determine the effect of gentamicin-containing collagen shields and gentamicin drops on Pseudomonas keratitis, a new keratotomy model of infection was employed. Model--contact lenses (58% water content) presoaked in 1% bovine serum albumin and exposed to 10(8) colony forming units per mL of Pseudomonas aeruginosa strain 27853, were found to reproducibly retain 5.9 (log base 10) colony-forming units. Rabbit corneas were scarified centrally with two perpendicular intersecting diamond knife cuts (5 mm x 5 mm x 0.2 mm), and bacteria-impregnated contact lenses were positioned and held in place for 24 hours with partial tarsorrhaphies. Treatment--Fourteen hours after lens removal (38 hours after infection), corneas were treated for 8 hours with collagen shields hydrated in saline (control), or shields impregnated with 800 micrograms gentamicin during manufacture, or one drop every 30 minutes of fortified gentamicin drops (14 mg/mL). The rabbits were killed and corneas collected for bacterial enumeration after 8 hours of treatment (46 hours after infection). Model--Slit-lamp examination and microbiologic confirmation showed uniformity of keratitis in all eyes. Treatment--Corneas treated with saline (controls) contained 6.4 (log base 10) Pseudomonas. Corneas treated with gentamicin-impregnated collagen shields (total drug = 800 micrograms) and fortified gentamicin drops (total drug = 21 mg) showed a reduction in viable bacteria of 2 logs and 6 logs, respectively, relative to the control. In this new model of Pseudomonas keratitis, the amount of gentamicin introduced into collagen shields during manufacture effectively reduced bacterial growth in infected rabbit corneas. However, larger amounts of drug applied as fortified drops on a frequent dosing schedule were more effective by a factor of three. Treatment of keratitis with antibiotic-impregnated collagen shields may reduce the need for very frequent application of topical drops, but may be more effective with topical drop supplementation to increase the amount of drug available over the course of therapy.

Effects of macrophage colony-stimulating factor on reduction of viable bacteria and survival of mice during Listeria monocytogenes infection: characteristics of monocyte subpopulations

Mice could well tolerate infection with a lethal dose of Listeria monocytogenes after intraperitoneal preinjections with 250 micrograms of macrophage colony-stimulating factor (M-CSF) per kg of body weight for 5 days. The characteristic changes in the surface markers (Mac-1, LFA-1, and F4/80) of peripheral monocytes were also investigated in order to analyze the mechanism of protection by M-CSF. This investigation shows the excellent effect of intraperitoneal preinjections of M-CSF on the reduction of viable Listeria organisms and the improvement of survival after an intravenous Listeria infection.

Evaluation of antibiotic effectiveness against Staphylococcus aureus surviving within the bovine mammary gland macrophage.

Bovine mastitis due to Staphylococcus aureus may become chronic and refractory to antibiotic therapy because of the organism's ability to survive within the mammary gland macrophages and/or polymorphonuclear neutrophils (PMNs). Therefore, phagocytosis and killing of S. aureus by bovine udder macrophages, udder and blood neutrophils and blood monocytes were studied. Gland and blood PMNs were about equally effective at phagocytosing (2.5 log reduction in supernatant) and killing the bacteria (92% reduction of viable bacteria by two hours). Gland macrophages phagocytosed at a lower rate (1.5 log reduction) and were less effective at killing the bacteria (73% reduction by two hours). Blood monocytes phagocytosed and killed S. aureus at the lowest rate. An udder macrophage monolayer system was developed and used to evaluate the ability of antibiotics to kill surviving intracellular S. aureus. This assay was similar to our previously described system with blood PMNs. Several classes of antibiotics were investigated. These included naphthalenic ansamycin, lincosaminide, tetracycline, coumarin, peptide, paulomycin, quinolone, macrolide, cephalosporin, and penicillin-class antibiotics. The activity of these compounds was compared to positive (rifampicin), negative (cloxacillin), and nonantibiotic treated controls. Only naphthalenic ansamycin class antibiotics, paulomycin, paldimycin and ciprofloxacin caused significant reduction in viable intracellular bacteria in the macrophage system. These results were similar to those obtained in the blood PMN monolayer system. Because a low intraphagolysosomal pH could affect an antibiotic's ability to kill intracellular bacteria by affecting the drug itself or inhibiting bacterial growth, the effect of low pH on the minimum inhibitory concentration and the minimum lethal concentration of clindamycin and rifampicin against three strains of S. aureus was also tested. While the activity of clindamycin at pH 5.0 compared to pH 7.0 was not affected greatly, the activity of rifampicin was greatly enhanced at acidic pH. These results suggest that at least some of the excellent activity of rifampicin for intracellular S. aureus is due to potentiation of its activity in the intracellular acidic compartment of the phagolysosome.

Chemotherapeutic efficacy of ofloxacin on renal and subcutaneous infection models with Staphylococcus aureus in mice.

Ofloxacin, a new pyridone-carboxylic acid derivative, was evaluated in descending nephritis and subcutaneous abscess models with Staphylococcus aureus in mice in comparison with norfloxacin. Descending nephritis was produced by intravenous injection of S. aureus 39 (MIC 0.78 microgram/ml for ofloxacin and 3.13 micrograms/ml for norfloxacin). Subcutaneous abscess was established by subcutaneous injection of soft agar containing S. aureus 56230 (MIC 0.39 microgram/ml for ofloxacin and 1.56 micrograms/ml for norfloxacin). Three days after infection, the lesions of both models were characterized by purulent inflammation accompanied with massive infiltration of neutrophils and bacterial multiplication. The animals were treated twice a day orally with each compound for 4 consecutive days, and subjected to bacteriological examination 18 h later. In the renal model, the 50% effective doses calculated on the basis of clearance of bacteria from kidneys were 38.4 mg/kg for ofloxacin and greater than 100 mg/kg for norfloxacin. In the subcutaneous model, the 50% effective doses based upon 90% reduction of viable bacteria as compared with untreated controls were 25.2 mg/kg for ofloxacin and greater than 100 mg/kg for norfloxacin. The excellent efficacies of ofloxacin in both infection models are attributed to its high oral absorbability and tissue distribution.

Effect of Spraying of Several Kinds of Disinfectant Solution on Reduction of Viable Bacteria

Effect of Spraying of Several Kinds of Disinfectant Solution on Reduction of Viable Bacteria

Bacterial contamination in feed ingredients, formulated chicken feed and reduction of viable bacteria by pelleting.

The number of bacteria in steam-pelleted or crumbled chicken food was compared with the number in individual ingredients and in mash. A few bacteria were detected in white-fish meal processed Alaska pollack. Highest yields were from alfalfa meal. Colonies numbering 3.5 x 10(3)-4.2 x 10(5) were obtained by heart-infusion agar culture, and 2.1 x 10(2)-7.0 x 10(4) with deoxycholate hydrogen sulphide lactose agar, from 1 g mash. After pelleting or crumbling the number of colonies in 1 g was reduced to 0-1.9 x 10(3) and 0-3.0 x 10(0) respectively. Bacteria in the lactose medium, mostly coliform, were observed in only 1 of 18 samples.