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PubMed2003

Enumeration and characterization of acidophilic microorganisms isolated from a pilot plant stirred-tank bioleaching operation.

Microorganisms were enumerated and isolated on selective solid media from a pilot-scale stirred-tank bioleaching operation in which a polymetallic sulfide concentrate was subjected to biologically accelerated oxidation at 45 degrees C. Four distinct prokaryotes were isolated: three bacteria (an Acidithiobacillus caldus-like organism, a thermophilic Leptospirillum sp., and a Sulfobacillus sp.) and one archaeon (a Ferroplasma-like isolate). The relative numbers of these prokaryotes changed in the three reactors sampled, and the Ferroplasma isolate became increasingly dominant as mineral oxidation progressed, eventually accounting for >99% of plate isolates in the third of three in-line reactors. The identities of the isolates were confirmed by analyses of their 16S rRNA genes, and some key physiological traits (e.g., oxidation of iron and/or sulfur and autotrophy or heterotrophy) were examined. More detailed studies were carried out with the Leptospirillum and Ferroplasma isolates. The data presented here represent the first quantitative study of the microorganisms in a metal leaching situation and confirm that mixed cultures of iron- and sulfur-oxidizing prokaryotic acidophiles catalyze the accelerated dissolution of sulfidic minerals in industrial tank bioleaching operations. The results show that indigenous acidophilic microbial populations change as mineral dissolution becomes more extensive.

Bacteria↗
PubMed1998

Bacterial cross-contamination of meat during liquid nitrogen immersion freezing.

Prerigor beef carcass surface tissue (BCT) was used to simulate lamb carcasses on a processing line with a 15-min liquid nitrogen (LN) immersion freezing step, and the potential for the dissemination of bacteria during freezing was examined. Streptomycin-resistant strains of Listeria innocua and Escherichia coli O157:H7 spiked into a fecal slurry were inoculated onto BCT pieces that were introduced into the freezing process to represent contaminated carcasses. Following this introduction, subsequently frozen uninoculated BCT, LN, and LN containers were examined for the inoculated organisms. In the first study, BCT samples were inoculated with ca. 7 log CFU/cm2 of both L. innocua and E. coli O157:H7, spray washed with water and frozen, distributed among uninoculated BCT, in LN for 15 min. In two separate trials, L. innocua was recovered by enrichment from all uninoculated BCT and LN samples. E. coli O157:H7 was also recovered from uninoculated BCT and LN, but this cross-contamination was more sporadic. Both species were recovered from the LN container following freezing. Attempts to enumerate cross-contaminating bacteria in the second trial indicated that contaminating levels were low (< 1.0 CFU/cm2 BCT). In a second study, a 2.0% lactic acid spray wash was used to reduce further the numbers of L. innocua introduced into the freezing system and resulted in fewer positive samples, although this organism was still recovered from many uninoculated BCT samples. When either bacterium was inoculated at lower initial levels (1.35 to 1.77 log CFU/cm2) and BCT was water or 2.0% lactic acid spray washed prior to freezing, neither L. innocua nor E. coli O157:H7 was recoverable by enrichment from uninoculated BCT, LN, or from the freezing container. Results demonstrate that bacterial cross-contamination of meat during LN immersion freezing can occur but indicate that the use of good sanitation practices and product with low microbial numbers can limit this occurrence.

Abattoirs↗
PubMed2001

Continuous online processing of fecal- and ingesta-contaminated poultry carcasses using an acidified sodium chlorite antimicrobial intervention.

The objective of this study was to determine the effectiveness of the combined use of an inside-outside-bird-washer for the removal of visible contamination and an online acidified sodium chlorite (ASC) spray system in reducing microbial levels on contaminated poultry carcasses. Specifically, we attempted to determine if this technique (referred to as continuous online processing [COP]) would (i) eliminate the need for offline reprocessing of contaminated carcasses, (ii) meet Zero Fecal Tolerance standards, and (iii) attain significant reductions in titers of some of the commonly found bacterial species. Carcasses were sampled for Ercherichia coli, Salmonella, and Campylobacter at five stations along the processing lines in a series of five commercial plant studies to compare the efficacy of the COP system to that of offline processing. The microbiological quality of fecally contaminated carcasses was found to be significantly better following COP treatment (E. coli, 0.59 log10 CFU/ml; Salmonella, 10.0% incidence) than after standard offline reprocessing (E. coli, 2.37 log10 CFU/ml; Salmonella, 31.6% incidence). Zero Fecal Tolerance requirements were met by all but 2 (0.2%) of the 1.127 carcasses following COP. COP also significantly reduced the titers of Campylobacter; residual titers were 1.14 log10 CFU/ml (49.1% incidence) following COP, compared to 2.89 log10 CFU/ml (73.2% incidence) in carcasses that underwent offline reprocessing. These results support the combined use of an inside-outside-bird-washer for the removal of visible contamination and an online ASC spray system to reduce microbial levels in commercially processed poultry.

Animals↗
PubMed2002

Potential for the spread of Escherichia coli O157, Salmonella, and Campylobacter in the lairage environment at abattoirs.

Prevalences of Escherichia coli O157, Salmonella spp., and Campylobacter spp. were examined in 270 swabs taken from selected sites along the unloading-to-slaughter routes of animal movement in lairages of six commercial abattoirs, three for cattle and three for sheep. The overall prevalences of the pathogens in the respective lairage environments were compared with those for 270 swabs from the pelts of 90 lambs examined in the present study and 270 swabs from the hides of 90 cattle examined in a previous study that were slaughtered at the same abattoirs on the same days. Also, the results obtained were analyzed with the aim of identifying critical points at which animal-environment-animal transfer of the pathogens in lairages occurs. The results showed that (i) the overall prevalences of E. coli O157, Salmonella spp., and Campylobacter spp. were 27.2, 6.1, and 1.1%, respectively, in cattle lairages and 2.2, 1.1, and 5.6%, respectively, in sheep lairages; (ii) the overall prevalences of the three pathogens on cow hides (28.8, 17.7, and 0%, respectively) and sheep pelts (5.5, 7.8, and 0%, respectively) were higher than the overall prevalences in the respective lairage environments; (iii) the most frequently contaminated sites in cattle lairages were holding pen floors (50% of swabs positive for one or more pathogens), entrance gates of stun boxes (27.8% of swabs positive for one or more pathogens), and stun box floors (22.2% of swabs positive for one or more pathogens); (iv) the most frequently contaminated sites in sheep lairages were unloading ramp floors, holding pen floors, and water troughs (33.3, 22.2, and 22.2%, respectively); and (v) overall, cattle lairages and cow hides were more frequently contaminated with the pathogens than were lamb lairages and lamb pelts. Further research is needed to develop strategies for the incorporation of pathogen control in lairages into integrated microbial meat safety systems.

Abattoirs↗
PubMed2006

Transfer coefficient models for escherichia coli O157:H7 on contacts between beef tissue and high-density polyethylene surfaces.

Risk studies have identified cross-contamination during beef fabrication as a knowledge gap, particularly as to how and at what levels Escherichia coli O157:H7 transfers among meat and cutting board (or equipment) surfaces. The objectives of this study were to determine and model transfer coefficients (TCs) between E. coli O157:H7 on beef tissue and high-density polyethylene (HDPE) cutting board surfaces. Four different transfer scenarios were evaluated: (i) HDPE board to agar, (ii) beef tissue to agar, (iii) HDPE board to beef tissue to agar, and (iv) beef tissue to HDPE board to agar. Also, the following factors were studied for each transfer scenario: two HDPE surface roughness levels (rough and smooth), two beef tissues (fat and fascia), and two conditions of the initial beef tissue inoculation with E. coli O157:H7 (wet and dry surfaces), for a total of 24 treatments. The TCs were calculated as a function of the plated inoculum and of the cells recovered from the first contact. When the treatments were compared, all of the variables evaluated interacted significantly in determining the TC. An overall TC-per-treatment model did not adequately represent the reduction of the cells on the original surface after each contact and the interaction of the factors studied. However, an exponential model was developed that explained the experimental data for all treatments and represented the recontamination of the surfaces with E. coli O157:H7. The parameters for the exponential model for cross-contamination with E. coli O157:H7 between beef tissue and HDPE surfaces were determined, allowing for the use of the resulting model in quantitative microbial risk assessment.

Animals↗
PubMedDate not supplied

[Changes in vaginal microbiocenosis in patients with chronic pelvic inflammatory diseases following antibiotic therapy].

The species composition of the vaginal microorganisms in healthy women and in patients with chronic pelvic inflammatory diseases before and after treatment in a gynecological hospital was studied. The study revealed that antibiotic therapy did not lead to complete clinical convalescence. During bacteriological investigation of patients changes in vaginal microbiocenosis, manifested by a decreased number of microbial species, an increased proportion of Escherichia coli, the occurrence of Staphylococcus aureus, a decreased number of Lactobacillus ssp., were observed. Antibiotic therapy aggravated the dysbiotic microbial picture of the vagina.

Adolescent↗
PubMed1998

Microbiological profile of raw Nile water.

With the increase of population on the Nile banks, a remarkable increase in industrial, agricultural, human activities, and recreational activities have also occurred. The effluents of such activities are discharged directly into the Nile or through some agricultural drains which finally discharge their wastes into the Nile. Thus, the microbiological monitoring is one of the main objectives to protect the river Nile. This study was conducted to determine the microbiological profile of river Nile at Cairo segment. Eight sites were chosen along the distance (60 Km) from El-Shobak to El-Kanater and tested for two successive years (summer 1994-spring 1996). To achieve this goal, microbiological parameters (total bacterial counts at both 22 degrees C and 37 degrees C, total coliforms, faecal coliforms, faecal streptococci, total yeasts, Candida albicans, Aeromonas hydrophila, salmonellae, total staphylococci, total vibrios and Listeria group) were evaluated. The results showed that the count of the previous parameters ranged between 1.0x10(3)-7.8x10(5) CFU/ml, 5.0x10(2)-6.4x10(5) CFU/ml, 4.9x10-1.6x10(4) MPN/100 ml, 2.0-5.2x0(3) MPN/100 ml, 2.0x10-1.4x10(3) MPN/100 ml, 1.7x10(3)-2.6x10(5) CFU/100 ml, 1.5x10(2)-1.7x10(5) CFU/100 ml, 1.0x10(3)-2.4x10(5) CFU/100 ml, 1.3x10(2)-5.1x10(3) CFU/100 ml, 1.0x10(2)-3.3x10(3) CFU/100 ml, 1.0x10(2)-3.8x10(4) CFU/100 ml and 1.0x10(2)-1.4x10(5) CFU/100 ml, respectively. The total bacterial counts and bacterial indicators (total coliforms, faecal coliforms and faecal streptococci) were detected in all samples during the period of study, and the count increased in samples collected during summer than other seasons. Also total yeasts, A. hydrophila and total staphylococci were detected in all samples with differences in count between the sites. In contrast, other microbial parameters, Candida albicans, salmonellae, total vibrios and Listeria group were not detected in some samples at some sites. According to our results it can be concluded that the river Nile is categorized as an intermediately polluted river.

Aeromonas hydrophila↗
PubMed1988

Post-processing microflora and the shelf stability of gari marketed in Port Harcourt.

Gari was examined for its post-processing microbial content. Aerobic mesophilic bacteria and fungi were isolated from all samples. The total viable bacterial counts ranged from 2.0 X 10(2) to 8.0 X 10(4) cfu/g. Fungal counts ranged from 1.0 X 10(2) to 1.5 X 10(4) cfu/g. The total viable counts of fresh samples were much lower than those of market and packaged samples. Bacillus, Micrococcus and Proteus spp. were the bacteria isolated, Aspergillus niger, Aspergillus flavus and Penicillium spp. the fungi. Food borne parasites and pathogens such as Staph. aureus and Clostridium perfringens were not found. The gari samples were quite stable, having a shelf life of 3-6 months. The water activities of the samples ranged from 0.52 to 0.68. Based on the microbial counts of the samples, the critical upper limit for the safety of gari was set at 10(4) cfu/g dry sample.

Bacteria, Aerobic↗
PubMed1997

[Programmed debridement, combined with jet lavage in extensive hand infections].

108 patients with a distinct infection of the hand were treated according to a protocol with serial debridements in combination with jet-lavage. In 106 patients the infection could be controlled with good functional result (79%) and normal neurological findings (85%). Microbial count in different tissues showed a significant decrease during the serial debridements.

Adolescent↗
PubMed2004

Assessing cytotoxicity of photosensitized transformation products of 2,4,6-trinitrotoluene (TNT) and atrazine with freshwater microbial assemblages.

In this study of riboflavin-sensitized photolysis of 2,4,6-trinitrotoluene (TNT), the final photoproducts were found to include 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, and 3,5-dinitroaniline. After exposure to TNT (10 mg/L) for 90 min, in a river water sample there was inhibition of the viability count of heterotrophic bacterial assemblages by 28.3% and 24.3% and of bacterial heterotrophic mineralization of glucose by 99.5% and 93.6% relative to the light control and dark control groups, respectively. After exposure separately to 10 mg/L 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, or 3,5-dinitroaniline, the viability count of heterotrophic bacterial assemblages was enhanced by 30.0%, 98.2%, and 148.7%, respectively, relative to the TNT group in light and by 12.2%, 40.2%, and 36.5%, respectively, relative to TNT group in dark. After exposure to the same aforementioned test chemicals, heterotrophic activity of bacterial assemblages was inhibited by 75.7%, 72.4%, and 56.0%, respectively, relative to light control group, and there were no significant changes in the dark. A similar study was conducted with atrazine (10 mg/L). The main products of atrazine riboflavin-sensitized phototransformation include desethylatrazine (DEA) and desisopropylatrazine (DIA). It was found that DEA and DIA did not inhibit microbial heterotrophic activity. However, after 72 h the viable count was enhanced by 52.8% and 63.3% in the DEA and DIA exposure groups, respectively, in comparison to the control. These results suggested that photosensitized transformation decreased TNT and atrazine cytotoxicity to microbial assemblages in the natural water. Photoproducts of atrazine--DEA and -DIA, and of TNT could become growth substrates for bacterial assemblages in natural water.

Atrazine↗
PubMed2002

[A new method of testing the effectiveness of sterile packaging in general practice].

The aim of our study was to develop a practical test for assessing the effectiveness of the microbial barrier of packaging materials for sterile products. The suitability of the test was verified in the exemplary case of double-wrapped sterilized trays. During testing, the bacterial count of the ambient air was 35 and 440 colony-forming units/cubic metre. The test is based on the co-sterilization in the sterile packing of petri dishes containing CASO agar, which at the end of the test were investigated for re-contamination. The petri dishes covered the sterilizing sieves as completely as possible. After sterilization, the packaging was loaded 300 to 900 times at a pressure of 1 kg (5x/min). This was followed by incubation for 48 hours at 37 degrees C, and evaluation (No. of colonies). The ability of the agar to culture colonies of bacteria was preserved unchanged for a period of at least 3 weeks after sterilization. For double-wrapped trays it was shown that re-contamination increases with intensity of mechanical loading and the atmospheric bacterial count. Since the package was breached only for the analysis, confounding factors due to removal of contents for examination, were effectively excluded. This test procedure is characterised by simplicity in handling and high specificity. As a final pack test it effectively closes a gap in the quality assurance chain for sterile materials.

Agar↗
PubMed1999

Effectiveness of hand-cleansing agents for removing Acinetobacter baumannii strain from contaminated hands.

BACKGROUND: The effectiveness of hand-cleansing agents (plain liquid soap, 70% ethyl alcohol, 10% povidone-iodine, and 4% chlorhexidine gluconate) for removing a hospital strain of Acinetobacter baumannii from artificially contaminated hands of 5 volunteers was studied. METHODS: The experiments were performed by using a Latin square statistical design, with two 5 x 4 randomized blocks, and the results were estimated by ANOVA. In the first and second blocks, the fingertips of the volunteers were contaminated with approximately 10(3) colony-forming units (light contamination hand) and 10(6) colony-forming units (heavy contamination hand), respectively. RESULTS: In the first block, all products tested were effective, almost completely removing the microbial population of A baumannii artificially applied to the hands. In the second block, the use of hand-cleansing agents resulted in 91.36% (4% chlorhexidine), 92.33% (liquid soap), 98.49% (10% povidone-iodine), and 98.93% (70% ethyl alcohol) reduction in counts of A baumannii cells applied to the fingertips. The ethyl alcohol and povidone-iodine had significantly higher removal rates than plain soap and chlorhexidine (P <.05). CONCLUSIONS: These results suggest that 70% ethyl alcohol and 10% povidone-iodine may be the most effective hand-cleansing agents for removing A baumannii strain from heavily contaminated hands (10(6) colony-forming units/fingertip).

Acinetobacter↗
PubMed2002

In situ antimicrobial effectiveness of chlorhexidine and calcium hydroxide: gel and paste versus gutta-percha points.

The aim of this study was to determine the antibacterial effectiveness of either chlorhexidine or calcium hydroxide integrated in gutta-percha points compared with chlorhexidine or calcium hydroxide delivered as gel or paste, respectively. A total of 70 initially sterile roots with open accesses were carried for 1 week in the oral cavities of two volunteers. The roots were then removed, and samples were taken from the root canals for microbial analysis. The roots were medicated with calcium hydroxide paste, 5% chlorhexidine gel, or a chlorhexidine- or calcium hydroxide-containing gutta-percha point. The accesses were closed with bonding material, and the roots incubated for 1 week. After removal of the antimicrobial agents, roots were again checked for bacterial growth. One thioglycolate-soaked paper point was then introduced into each canal, and roots were incubated for 1 week more to observe bacterial regrowth. After 1 week of medication, the absolute bacterial count revealed significant differences compared with the controls. However, only the chlorhexidine-gel and the calcium hydroxide paste group showed no microbial colonization in a considerable number of samples after 1 and 2 weeks.

Anti-Infective Agents, Local↗
PubMed1989

A review of bioluminescent ATP techniques in rapid microbiology.

Use of firefly luciferase to assay adenosine triphosphate (ATP) extracted from microorganisms provides an easy means to enumerate microbes within minutes. The small amount of light produced is proportional to ATP and thus microbial number. The average bacterium contains around 10(-15) g ATP per cell. Present reagents permit detection of 10(3) cells per tube. Luminometers currently on the market detect about 10(-12) g ATP. Proper extraction of ATP from the microbes is an essential part of any protocol, as is the removal of non-microbial ATP from, for example, somatic cells also present in samples. The technique may be applied to a wide range of samples, for example food and beverages and clinical samples such as urine. The ATP assay gives a global measure of microbial numbers, i.e. it is not species specific unless a species separation step is included in the protocol.

Adenosine Triphosphate↗
PubMed1994

Motility and chemotaxis in Bacillus sphaericus. Dependence upon stage of growth.

Chemotaxis and motility of Bacillus sphaericus 2362 were monitored as a function of the batch culture age. It was found that both functions changed independently during growth of the culture. Motility was low until the late logarithmic stage ensued, whereafter it increased sharply. The ability of cells to respond to chemo-effectors peaked at the mid-logarithmic phase. A major methyl-accepting chemotaxis protein (P53, M(r) = 53 kDa) was identified. The extent of label incorporation in this protein from L-[methyl-3H]methionine was maximal in mid- and late-logarithmic phases of the growth. Cells in stationary cultures incorporated very low amounts of the label. At any stage, the labeling was maximal in starved cells; it was almost abolished in cells pre-incubated with amino acids. Although extents of P53 labeling in mid- and late logarithmic cells were similar, late logarithmic cells demonstrated a considerably impaired chemotaxis. Supermotile sporulating cells were practically insensitive to environmental stimuli. The difference in development of sensory and locomotive functions may be interpreted as an adaptive response. A well developed sensory apparatus would allow vegetative cells to adapt efficiently to fluctuating attractant gradients. Insensitive sporulating cells would tend to disperse randomly from the nutrient-exhausted area. Thus, spore formation would occur in larger volume of the habitat, increasing the chance of microbial population to survive.

Alanine↗
PubMed1994

Motility and chemotaxis in Bacillus sphaericus. Dependence upon stage of growth.

Chemotaxis and motility of B. sphaericus 2362 were monitored as the function of a batch culture age. It was found that both functions changed independently during growth of the culture. Motility was low until the late logarithmic stage ensued, whereafter it increased sharply. The ability of cells to respond to chemoeffectors peaked at the mid-logarithmic phase. A major methyl-accepting chemotaxis protein (P53, M(r) = 53 kDa) was identified. The extent of label incorporation in this protein from L-[methyl-3H]methionine was maximal in mid- and late logarithmic phases of the growth. Cells in stationary cultures incorporated very low amounts of the label. At any stage, the labeling was maximal in starved cells; it was almost abolished in cells pre-incubated with amino acids. Although extents of P53 labeling in mid- and late logarithmic cells were similar, late logarithmic cells demonstrated a considerably impaired chemotaxis. Supermotile sporulating cells were practically insensitive to environmental stimuli. The difference in development of sensory and locomotive functions may be interpreted as an adaptive response. A well developed sensory apparatus would allow vegetative cells to adapt efficiently to fluctuating attractant gradients. Insensitive sporulating cells would tend to disperse randomly from the nutrient-exhausted area. Thus, spore formation would occur in larger volume of the habitat, increasing the chance of the microbial population to survive.

Alanine↗