Partnering for better microbial diagnostics.
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Bacterial Infections↗
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Results for “Colony Count, Microbial”
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Microbiology. Microbial life breathes deep.
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Archaea↗
Use of portable microbial samplers for estimating inhalation exposure to viable biological agents.
Portable microbial samplers are being increasingly used to determine the presence of microbial agents in the air; however, their performance characteristics when sampling airborne biological agents are largely unknown. In addition, it is unknown whether these samplers could be used to assess microbial inhalation exposure according to the particle sampling conventions. This research analyzed collection efficiencies of MAS-100, Microflow, SMA MicroPortable, Millipore Air Tester, SAS Super 180, BioCulture, and RCS High Flow portable microbial samplers when sampling six bacterial and fungal species ranging from 0.61 to 3.14 microm in aerodynamic diameter. The efficiencies with which airborne microorganisms were deposited on samplers' collection medium were compared to the particle inhalation and lung deposition convention curves. When sampling fungi, RCS High Flow and SAS Super 180 deposited 80%-90% of airborne spores on agar - highest among investigated samplers. Other samplers showed collection efficiencies of 10%-60%. When collecting bacteria, RCS High Flow and MAS-100 collected 20%-30%, whereas other samplers collected less than 10% of these bioparticles. Comparison of samplers' collection efficiencies with particle inhalation convention curves showed that RCS High Flow and SAS Super 180 could be used to assess inhalation exposure to particles larger than 2.5 microm, such as fungal spores. Performance of RCS High Flow sampler was also reflective of the particle lung deposition pattern when sampling both bacteria and fungi. MAS-100 and SAS Super 180 matched the total deposition curve fairly well when collecting bacterial and fungi species, respectively. For other tested samplers, we observed substantial discrepancies between their performances and particle deposition efficiencies in the lung. The results show that feasibility of applying portable microbial samplers for exposure assessment depends on a particular sampler model and microbial species.
Aerosols↗
Microbial activity in aquatic environments measured by dimethyl sulfoxide reduction and intercomparison with commonly used methods.
A new method to determine microbial (bacterial and fungal) activity in various freshwater habitats is described. Based on microbial reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS), our DMSO reduction method allows measurement of the respiratory activity in interstitial water, as well as in the water column. DMSO is added to water samples at a concentration (0.75% [vol/vol] or 106 mM) high enough to compete with other naturally occurring electron acceptors, as determined with oxygen and nitrate, without stimulating or inhibiting microbial activity. Addition of NaN(3), KCN, and formaldehyde, as well as autoclaving, inhibited the production of DMS, which proves that the reduction of DMSO is a biotic process. DMSO reduction is readily detectable via the formation of DMS even at low microbial activities. All water samples showed significant DMSO reduction over several hours. Microbially reduced DMSO is recovered in the form of DMS from water samples by a purge and trap system and is quantified by gas chromatography and detection with a flame photometric detector. The DMSO reduction method was compared with other methods commonly used for assessment of microbial activity. DMSO reduction activity correlated well with bacterial production in predator-free batch cultures. Cell-production-specific DMSO reduction rates did not differ significantly in batch cultures with different nutrient regimes but were different in different growth phases. Overall, a cell-production-specific DMSO reduction rate of 1.26 x 10(-17) +/- 0. 12 x 10(-17) mol of DMS per produced cell (mean +/- standard error; R(2) = 0.78) was calculated. We suggest that the relationship of DMSO reduction rates to thymidine and leucine incorporation is linear (the R(2) values ranged from 0.783 to 0.944), whereas there is an exponential relationship between DMSO reduction rates and glucose uptake, as well as incorporation (the R(2) values ranged from 0.821 to 0.931). Based on our results, we conclude that the DMSO reduction method is a nonradioactive alternative to other methods commonly used to assess microbial activity.
Bacteria↗
Evaluation of the efficacy of Alpron disinfectant for dental unit water lines.
AIMS: To assess the efficacy of a disinfectant, Alpron, for controlling microbial contamination within dental unit water lines. METHODS: The microbiological quality of water emerging from the triple syringe, high speed handpiece, cup filler and surgery hand wash basin from six dental units was assessed for microbiological total viable counts at 22 degrees C and 37 degrees C before and after treatment with Alpron solutions. RESULTS: The study found that the use of Alpron disinfectant solutions could reduce microbial counts in dental unit water lines to similar levels for drinking water. This effect was maintained in all units for up to six weeks following one course of treatment. In four out of six units the low microbial counts were maintained for 13 weeks. CONCLUSIONS: Disinfectants may have a short term role to play in controlling microbial contamination of dental unit water lines to drinking water quality. However, in the longer term attention must be paid to redesigning dental units to discourage the build up of microbial biofilms.
Amines↗
Calcium alginate swab versus Bard Parker blade in the diagnosis of microbial keratitis.
A prospective comparative evaluation of Bard Parker blade no. 15 and calcium alginate swab in the collection of corneal material was conducted. The study group included 30 consecutive cases of bacterial (n = 17), fungal (n = 11), and mixed (n = 2) cases of microbial keratitis. The samples collected by blade and swab were processed in an identical manner for viable colony counts. The yields from blade and swab were compared using the proportion test, taking into consideration the mean counts of each organism. The swab yielded significantly greater growth than blade (p = 0.003) in mycotic ulcers. However, the two patients (2/11) who showed no growth by blade but were positive by swab had smears positive and were diagnosed as mycotic ulcers. The difference between the two methods was not significant for bacterial and mixed ulcers. Replacement of blade with calcium alginate swab did not appear to be advantageous for the investigation of infectious keratitis.
Alginates↗
Microbiology. Exploring microbial diversity--a vast below.
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Bacteria↗
Effects of voriconazole, granulocyte-macrophage colony-stimulating factor, and interferon gamma on intracellular fluconazole-resistant Candida glabrata and Candida krusei in human monocyte-derived macrophages.
Infections caused by fluconazole-resistant Candida glabrata and Candida krusei are increasingly common causes of morbidity and mortality. We investigated the intracellular killing of fluconazole-resistant C. glabrata and C. krusei by cytokine-activated human monocyte-derived macrophages (MDM) in the presence and absence of voriconazole. For C. glabrata, MDM were activated with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interferon gamma (IFN-gamma) before infection, after infection, or both before and after infection, whereas for C. krusei MDM were activated with cytokines both before and after infection. Activated MDM were infected, treated with voriconazole, and then lysed, and viable yeast in the lysates enumerated at 0, 24, or 48 h after infection. In the presence of voriconazole (2.5 x MIC), the best activity against C. glabrata occurred when MDM were activated with GM-CSF for 24 h before infection as well as after infection or when they were activated for 24 h before infection alone. A lesser effect was observed when MDM were activated for at least 1 h before infection or when they were treated with cytokines only after infection. IFN-gamma activation had a significant but lesser effect than GM-CSF. Activity against C. krusei in the presence of voriconazole was greatest when MDM were activated with IFN-gamma rather than GM-CSF. Our results suggest that cytokines increase the intracellular anticandidal effect of voriconazole and may be useful as therapeutic adjuvants to voriconazole for treatment of infections caused by fluconazole-resistant C. glabrata and C. krusei.
Antifungal Agents↗
Granulocyte-macrophage colony-stimulating factor (GM-CSF)-coated implants and their potential for reducing biomaterial-associated infection in neutropenic hosts.
The incidence of infections associated with the use of medical biomaterials is high for skin-penetrating devices, when microbes of the normal skin flora like coagulase-positive and coagulase-negative staphylococci dominate as causative organisms. The most serious ones are infections in immunocompromised individuals. A mouse model of subcutaneous staphylococcal infection yielding abscesses in cyclophosphamide-induced neutropenic mice implanted with heparinized polyethylene (H-PE) was used. The present study addresses the question of the effects of implant modification with recombinant granulocyte-macrophage stimulating factor (rGM-CSF) on the course of infection. Our findings demonstrate that such modification reduces the proliferation of bacteria within the abscess and as a consequence limits the dissemination of bacteria from the local infection induced in the neutropenic host.
Abscess↗
Liposomal amphotericin B and granulocyte colony-stimulating factor therapy in a murine model of invasive infection by Scedosporium prolificans.
We established a reproducible lethal disseminated infection by the opportunistic fungus Scedosporium prolificans in an immunosuppressed murine model. We compared the effectiveness of the combined administration of liposomal amphotericin B (LAMB) and granulocyte colony-stimulating factor (G-CSF) with that of either agent alone and with that of amphotericin B deoxycholate (AMB). LAMB + G-CSF and LAMB treatments improved survival significantly with respect to the untreated control. The mean survival times of these three groups were 13.2, 9.1 and 7.9 days, respectively. Culture results in terms of colony counts for samples of deep organs were lower in mice treated with the combined therapy, although differences were not significant. Combined LAMB + G-CSF therapy could be a promising approach for the treatment of disseminated infections of S. prolificans, although further studies are required to determine the most appropriate doses.
Amphotericin B↗
Different meningitis-causing bacteria induce distinct inflammatory responses on interaction with cells of the human meninges.
The interactions of bacterial pathogens with cells of the human leptomeninges are critical events in the progression of meningitis. An in vitro model based on the culture of human meningioma cells was used to investigate the interactions of the meningeal pathogens Escherichia coli K1, Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae. A rank order of association with meningioma cells was observed, with N. meningitidis showing the highest levels of adherence, followed by E. coli, S. pneumoniae and H. influenzae. Neisseria meningitidis and H. influenzae did not invade meningioma cells or induce cell death, but induced a concentration-dependent secretion of inflammatory mediators. Neisseria meningitidis induced higher levels of IL-6, MCP-1, RANTES and GM-CSF than H. influenzae, but there was no significant difference in the levels of IL-8 induced by both pathogens. Streptococcus pneumoniae was also unable to invade meningioma cells, but low concentrations of bacteria failed to stimulate cytokine secretion. However, higher concentrations of pneumococci led to cell death. By contrast, only E. coli K1 invaded meningioma cells directly and induced rapid cell death before an inflammatory response could be induced. These data demonstrate that the interactions of different bacterial pathogens with human meningeal cells are distinct, and suggest that different intervention strategies may be needed in order to prevent the morbidity and mortality associated with bacterial meningitis.
Bacterial Adhesion↗
A bacteriological assessment of multibacillary cases in leprosy colonies after 4 1/2 years of multidrug therapy.
In this presentation we have devised a novel way of calculating the total bacterial quantum in 100 (78 LL and 22 BL) multibacillary leprosy patients living in leprosy colonies. The calculation is based on Ridley's logarithmic scale. We have also attempted to assess the reduction in the bacterial quantum as a result of intervention through multidrug therapy (MDT). 53% of the patients rendered bacteriologically negative within two years of treatment of MDT and 94% at 54th pulse dose i.e. at 54th month. The bacterial quantum in human source as leprosy patients was calculated thus--Average BI of the group X Number of patients in each group X Multiplication factor devised as per Ridley's Bacterial Index (BI). By applying this purely arithmetic formula, it was found that 99.8% of the bacterial load is harboured in leprosy patients having BI more than 3. The introduction of MDT initiated the reduction in total bacterial quantum "based on above arithmetic scale" was achieved very fast i.e., from 100% to 5% at 12 months and to 0.4% at 24 months. We believe that if one wants to achieve leprosy control through a reduction in total bacterial quantum within a specific period, leprosy cases with BI more than 3 should be treated on priority basis.
Colony Count, Microbial↗
The effect of granulocyte colony-stimulating factor (G-CSF) on bacterial translocation in the splenectomized rat.
BACKGROUND/AIMS: We created a study group in order to investigate the effects of splenectomy and filgrastim. Filgrastim is an immunomodulator granulocyte colony-stimulating factor (G-CSF), that affects bacterial translocation. MATERIALS AND METHODS: We created 3 study groups with 30 male Sprague-Dawley rats; the first group included sham splenectomy, the second group was splenectomy, and the third group was splenectomy+ filgrastim group. RESULTS: The mean bacterial colony count of the cecum were 2.5 x 10(9) in group 1, 1.2 x 10(10) in group 2 and 3.5 x 10(9) in group 3. The differences between these groups were accepted as statistically significant. The mean counts of the terminal ileum were 1.1 x 10(9) in group 1, 5.5 x 10(10) in group 2 and 2.5 x 10(10) in group 3. The p values of group 1-2 were 0.036 (statistically significant) and 0.123 in groups 2-3) were not statistically significant. The mean counts of the liver were 0.2 x 10(4), 1 x 10(10) and 3.4 x 10(5), respectively. In comparison of the groups the p values of the first and last 2 groups were found to be 0.047 (statistically significant). The mean counts of the mesenteric lymph node were 0.7 x 10(3), 1 x 10(10) and 0.9 x 10(6) respectively. The p values were 0.343 for the first and the last 2 groups both. As they were above 0.05, they were not statistically significant. The degrees of liver Kupffer cell hyperplasia were (+) 40%, (+2) 50% and (+3) 10% (group 1), (+) 10%, (+2) 40% and (+3) 50% (group 2), (+2) 60% and (+3) 40% (group 3) (p = 0.0039). The rates of the absence of pathology in mesenteric lymph nodes were 70% (group 1), 90% (group 2) and 100% (group 3) (p = 0.049). These findings were statistically significant. CONCLUSIONS: We found that splenectomy has activated the whole predisposing factors of bacterial translocation and created the latter itself. In addition, we showed that filgrastim, a recently widespread used G-CSF, decreases bacterial translocation significantly.
Adjuvants, Immunologic↗
Spectral imaging detection and counting of microbial cells in marine sediment.
Semiautomated detection and counting techniques for microbial cells in soil and marine sediment using microscopic-spectral-imaging analysis were developed. Microbial cells in microscopic fields were selectively detected from other fluorescent particles by their fluorescent spectrum, based on the spectral shift between the conjunction and nonconjunction of DNA fluorochrome (SYBR Green II) with nucleic acids. Using this technique, microbial cells could be easily detected in soil and 30-cm deep sediment samples from Tokyo Bay, both of which contain particles other than microbial cells. Total cell density was semiautomatically estimated at 1-6 x 10(9) cells cm(-3) of sediment sampled at different depths in Tokyo Bay, which corresponded to 65-106% (mean 88%) of visual direct counting. This technique may be useful for detecting microbial cells in soil and sediment samples from the deeper subsurface environment.
Bacteria↗
Levels of naturally occurring microorganisms on surgical instruments after clinical use and after washing.
Surgical instruments exposed to sterile body sites should be contaminated with relatively low levels of microbial contamination or bioburden; however, few studies in the literature have determined the quantitative level and types of contamination. A study was conducted at 2 clinical sites to determine the level of microbial contamination of surgical instruments after clinical use and after washing. Quantitative assays showed that bioburden levels were in the range of 0 to 4415 colony forming units per instrument after clinical use, and 88% of the instruments had bioburden levels lower than 1000. As expected, a reduction in counts occurred after washing; however, in some cases, higher counts were found on the instruments after the washing process. Although the washing procedure is effective in reducing the microbial levels deposited on the surgical instruments during use, a recontamination process occurs that results in increased counts after washing. The low bioburden level after washing consists of predominantly vegetative microorganisms that present a relatively low challenge to sterilization and disinfection systems.
Colony Count, Microbial↗
Averaging of TNTC counts.
When plate count methods are used for microbial enumeration, if too-numerous-to-count results occur, they are commonly discarded. In this paper, a method for consideration of such results in computation of an average microbial density is developed, and its use is illustrated by example.
Bacteria↗
Intense light pulses decontamination of minimally processed vegetables and their shelf-life.
Intense light pulses (ILP) is a new method intended for decontamination of food surfaces by killing microorganisms using short time high frequency pulses of an intense broad spectrum, rich in UV-C light. This work studied in a first step the effect of food components on the killing efficiency of ILP. In a second step, the decontamination of eight minimally processed (MP) vegetables by ILP was evaluated, and thirdly, the effect of this treatment on the shelf-life of MP cabbage and lettuce stored at 7 degrees C in equilibrium modified atmosphere packages was assessed by monitoring headspace gas concentrations, microbial populations and sensory attributes. Proteins and oil decreased the decontamination effect of ILP, whilst carbohydrates and water showed variable results depending on the microorganism. For this reason, high protein and fat containing food products have little potential to be efficiently treated by ILP. Vegetables, on the other hand, do not contain high concentrations of both compounds and could therefore be suitable for ILP treatment. For the eight tested MP vegetables, log reductions up to 2.04 were achieved on aerobic mesophilic counts. For the shelf-life studies, respiration rates at 3% O2 and 7 degrees C were 14.63, 17.89, 9.17 and 16.83 ml O2/h kg produce for control and treated cabbage, and control and treated lettuce respectively; used packaging configurations prevented anoxic conditions during the storage times. Log reductions of 0.54 and 0.46 for aerobic psychrothrophic count (APC) were achieved after flashing MP cabbage and lettuce respectively. APC of treated cabbage became equal than that from control at day 2, and higher at day 7, when the tolerance limit (8 log) was reached and the panel detected the presence of unacceptable levels of off-odours. Control never reached 8 log in APC and were sensory acceptable until the end of the experiment (9 days). In MP lettuce, APC of controls reached rejectable levels at day 2, whilst that of treated samples did after 3 days. Both samples were sensory unacceptable at day 3, controls because of bad overall visual quality (OVQ), off-odour and leaf edge browning and treated samples due to bad OVQ; browning inhibitors might be proposed to preserve OVQ. Yeasts and lactic acid bacteria counts were low in all the samples. It seems that ILP treatment alone under the conditions used in this work does not increase MP vegetables shelf-life in spite of the reduction in the initial microbial load.
Bacteria↗
Cross-contamination in the dental laboratory through the polishing procedure of complete dentures.
Polishing of dental prostheses can cause a dangerous cycle of cross-contamination involving dentists, laboratory technicians, patients and auxiliary personnel. The aim of this study was to show the microbial contamination in the dental laboratory during the polishing procedure of complete dentures. For this purpose, 4 experiments were conducted. Experiment I -- Determination of the total colony-forming units (CFU) counts contaminating complete maxillary dentures. During the polishing procedure, determination of the CFU counts transferred to the operator (Experiment II) and of the total CFU counts transferred to previously sterilized complete dentures (Experiment III). Experiment IV -- The total counts of remaining CFU in the lathe spindle after Experiments II and III. Complete dentures were highly contaminated (mean = 1.4 x 10(7) CFU/mL). There was a elevated level of contamination by splatter and aerosols. There was high microbial transfer from the contaminated lathe spindle to the sterile prostheses (mean = 1.7 x 10(7) CFU/mL). The spindles were highly contaminated after polishing procedures (mean = 3.5 x 10(8) CFU/mL). The polishing of dental prostheses is a possible source of transmission of communicable diseases in the laboratory and requires improved techniques for infection control.
Adult↗