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PubMed1967

Microbial destruction by low concentrations of hypochlorite and iodophor germicides in alkaline and acidified water.

Hypochlorite and iodophor germicides were evaluated for their ability to destroy a variety of organisms at levels approximating those used for final sanitizing rinse for dairy and food equipment and beverage bottles (3 to 50 ppm). Test organisms included Escherichia coli, Streptococcus lactis, Lactobacillus plantarum, Pediococcus cerevisiae, and Saccharomyces cerevisiae. The hypochlorites and iodophors demonstrated approximate rates of destruction at equivalent concentrations for the bacterial species tested, except where the hypochlorite contained excess alkalinity. The hypochlorite responded more readily to a downward shift to a pH of 5.0 than did the iodophor. Excess alkalinity of the hypochlorite significantly affected its bactericidal activity. The iodophor exhibited a consistently greater rate of destruction of yeast cells than the hypochlorite. Successive treatment with low levels of iodophor (6 ppm) followed by a hypochlorite (12 to 25 ppm) resulted in a high level of destruction of all test organisms. Possibilities for employing these measures in a sanitizing rinse of bottles for maximal destruction of organisms were discussed. Among the test organisms, S. lactis showed a comparatively high resistance and was a useful organism for comparing the halogen preparations.

Chlorine↗

PubMed1967

Effect of algicidal quaternaries on the germicidal activity of chlorine on swimming pool water.

The Swimming Pool Water Disinfectant Test Method of the Association of Official Analytical Chemists was used to determine the effect of the accepted level of 2 ppm of some commercial quaternary ammonium algicides on the germicidal activity of chlorine. Accurate determinations on the amounts of residual available chlorine in chlorine-quaternary mixtures could not be made by the usual chemical methods. This made it necessary to base all comparisons on the starting concentrations of available chlorine rather than the final concentration as specified in the method employed. No evidence was obtained to support the use of lower concentrations of residual available chlorine for disinfection in the presence of algicidal quaternaries than those commonly recognized as effective by the American Public Health Association. The rate of kill against the gram-positive test organism Streptococcus faecalis was faster in quaternary-chlorine mixtures than in the sodium hypochlorite control solutions. The practical significance of this result in the bench method identified cannot be ascertained in the absence of more sensitive and precise chemical procedures for determining concentrations of residual available chlorine in the presence of quaternaries or in actual swimming pool tests.

Chlorine↗

PubMed1999

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study.

OBJECTIVES: The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination. METHODS: GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi. RESULTS: Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on. CONCLUSION: Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

Adult↗

PubMed2004

Disinfection of selected Aspergillus spp. using ultraviolet germicidal irradiation.

AIMS: The efficacy of ultraviolet germicidal irradiation (UVGI) and the UVGI dose necessary to inactivate fungal spores on an agar surface for cultures of Aspergillus flavus and Aspergillus fumigatus were determined. METHODS AND RESULTS: A four-chambered UVGI testing unit with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber was used in this study. An aperture was adjusted to provide 50, 100, 150, and 200 micro W/cm2 of uniform flux to the surfaces of the Petri dish, resulting in a total UVGI dose to the surface of the Petri dishes ranging from 12 to 96 mJ/cm2. The UVGI dose necessary to inactivate 90% of the A. flavus and A. fumigatus was 35 and 54 mJ/cm2, respectively. CONCLUSIONS: UVGI can be used to inactivate culturable fungal spores. Aspergillus flavus was more susceptible than A. fumigatus to UVGI. SIGNIFICANCE AND IMPACT OF THE STUDY: These results may not be directly correlated to the effect of UVGI on airborne fungal spores, but they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores traveling through the irradiated zone.

Aspergillus flavus↗

PubMed2005

Ultraviolet germicidal irradiation disinfection of Stachybotrys chartarum.

The ultraviolet germicidal irradiation (UVGI) dose necessary to inactivate fungal spores on an agar surface and the efficacy of UVGI were determined for cultures of Stachybotrys chartarum (ATCC 208877). This study employed a UVGI testing unit consisting of four chambers with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber. The testing unit's apertures were adjusted to provide 50, 100, 150, and 200 microW/cm2 of uniform flux to the Petri dish surfaces, resulting in a total UVGI surface dose ranging from 12 to 144 mJ/cm2. The UVGI dose necessary to inactivate 90% of the S. chartarum was greater than the maximum dose of 144 mJ/cm2 evaluated in this study. While UVGI has been used to inactivate several strains of culturable fungal spores, S. chartarum was not susceptible to an appropriate dose of UVGI. The results of this study may not correlate directly to the effect of UVGI on airborne fungal spores. However, they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores, such as S. chartarum, traveling through the irradiated zone.

Colony Count, Microbial↗

PubMedDate not supplied

Surface germicidal effects of ozone for microorganisms.

In this study the influences of microorganism species, relative humidity, and ozone dosage on ozone surface disinfection were evaluated. Bacterial and fungal cultures were spread on agar plates and exposed to ozone. The selected microorganisms included Escherichia coli, Bacillus subtilis, Candida famata, and Penicillium citrinum. Results showed that microorganism survival fraction and ozone dosage (ozone concentration times exposure time) have an exponential relationship. Results also indicated that E. coli was the most sensitive organism to ozone exposure. E. coli required only very low ozone doses of 2-2.5 and 3.5-4 mg to obtain 50 and 80% inactivation, respectively. In addition, P. citrinum was more resistant than E. coli and required ozone doses of 40-60 and 60-120 mg to obtain 50 and 80% inactivation. In addition, spores of B. subtilis were observed to be the most resistant organism, requiring ozone doses of 40-75 and 145-150 mg to obtain 50 and 80% inactivation. Yeast was less resistant than P. citrinum and B. subtilis, requiring ozone doses of 10 and 15-19 mg to obtain 50 and 80% inactivation. It was clearly indicated that the ozone dose differences for 80% microorganism inactivation could be as high as 40 times between B. subtilis and E. coli. Ozone surface germicidal efficiency increased as relative humidity increased, which could be related to more radicals generated from ozone reaction with more water vapor at higher relative humidity. It was concluded that ozone should be highly effective and provide a reliable safety factor in treating contaminated surface. In addition, workers might need to wear suitable respiratory protection at high ozone level operation.

Bacteria↗

PubMed1985

Inactivation of bacteria and viruses in water: passage of germicidal ultraviolet light through Teflon.

Teflon pipe as used in a water purification system transmitted germicidal ultraviolet (UV) light to inactivate Pseudomonas aeruginosa and poliovirus. The information is useful for animal care workers and others concerned with the prevention of microbial growth in water systems such as deionizers and distilled water. Of special significance is that there is a plastic that transmits UV light.

Poliovirus↗

PubMed2002

The characterization of upper-room ultraviolet germicidal irradiation in inactivating airborne microorganisms.

In this study, we explored the efficacy of upper-room ultraviolet germicidal irradiation (UVGI) in reducing the concentration of Serratia marcescens and Mycobacterium bovis bacille Calmette-Guérin (BCG) aerosols in enclosed places. We constructed a facility (4.5 m x 3 m x 2.9 m) in which both ceiling- and wall-mounted UV fixtures (UV output: 10W and 5W respectively) were installed. The use of ceiling- and wall-mounted UV fixtures (total UV output: 15W) without mixing fan reduced the concentration of S. marcescens aerosols by 46% (range: 22-80%) at 2 air changes per hour (ACH) and 53% (range: 40-68%) at 6 ACH. The use of ceiling- and wall-mounted UV fixtures with mixing fan increased the UV effectiveness in inactivating S. marcescens aerosols to 62% (range: 50-78%) at 2 ACH and to 86% (81-89%) at 6 ACH. For BCG aerosols, UV effectiveness in inactivating BCG aerosols at 6 ACH were 52% (range: 11-69%) by ceiling-mounted UV fixture only (total UV output: 10W) and 64% (51-83%) by both ceiling- and wall-mounted UV fixtures (total UV output: 15W). Our results indicated that the equivalent ventilation rate attributable to upper-room UVGI for BCG aerosols ranged from 1 ACH to 22 ACH for ceiling-mounted UV fixtures and from 6.4 ACH to 28.5 ACH for ceiling- and wall-mounted UV fixtures. Both generalized linear and generalized additive models were fitted to all our data. The regression results indicated that the number of UV fixtures, use of mixing fan, and air exchange rate significantly affected UV effectiveness (p < 0.01, 0.01, 0.01 respectively). However, the strain difference (S. marcescens vs. BCG) appeared less important in UV effectiveness (p = 0.26). Our results also indicated that UV effectiveness increased at higher temperature ((italic)p(/italic) < 0.01), lower dry-bulb temperature ((italic)p(/italic) = 0.21), and colder air from a supply grill located near the ceiling (p = 0.22).

Aerosols↗

PubMed1983

Germicidal teat dip in a herd with low prevalence of Streptococcus agalactiae and Staphylococcus aureus mastitis.

Effectiveness of an iodophor teat dip in reducing new intramammary infection and clinical mastitis was tested in a herd free of Streptococcus agalactiae and with a low prevalence of Staphylococcus aureus infections. In this 6-mo study with an average of 152 lactating cows on trial on sampling dates, right rear and left front teats were dipped after each milking while right front and left rear teats were undipped controls. Teat dipping significantly reduced new infections by Staphylococcus aureus, streptococci (other than Streptococcus agalactiae), coagulase-negative staphylococci, and Corynebacterium bovis and reduced clinical cases caused by infections established during the trial. However, the dip did not reduce new infections or clinical mastitis caused by coliform bacteria. Therefore, use of a germicidal dip is recommended for herds with a low prevalence of Streptococcus agalactiae and Staphylococcus aureus, but the practice should not be expected to control coliform mastitis.

Administration, Topical↗

PubMed1988

Determination of teat dip germicidal activity using the excised teat model.

Fifteen postmilking teat antiseptics were evaluated in seven trials using the excised teat model. All products were tested against Staphylococcus aureus Newbould 305 and Streptococcus agalactiae Cornell 48. Eight of nine iodophor products provided log reductions greater than 3 against Staph. aureus and Strep. agalactiae. A .045% iodophor product was ineffective. A .5% chlorhexidine product yielded a log reduction of 3.22 against Staph. aureus but only 2.92 against Strep. agalactiae. Two products containing fermented milk emulsified in detergent were tested upon receipt and after 1 yr storage. Fresh product provided log reductions greater than 3 against both pathogens. Storage for 1 yr resulted in minimal loss of germicidal activity. Three products containing 1, .5, and .2% dodecylaminoalkyl glycine provided log reductions greater than 3.5 against Staph. aureus and greater than 4 log reduction against Strep. agalactiae.

Animals↗

PubMed1992

In vitro germicidal activity of teat dips against Nocardia asteroides and other udder pathogens.

Nine commercial teat dip formulations containing 1.94% linear dodecylbenzene sulfonic acid, or 1% available iodine from nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex, or .5% chlorhexidine acetate were tested for contamination with aerobic and anaerobic bacteria and their in vitro germicidal activity against Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Nocardia asteroides. All products were free of bacteria when neutralized samples were tested on blood agar or liquid thioglycollate media. To test for in vitro efficacy, each teat dip preparation was mixed with a suspension of one of the pathogenic test organisms containing 10(8) bacteria/ml (final concentration) for .5 to 15 min. Viable bacteria were evaluated by direct plating of neutralized aliquots and by filtration techniques. All products were effective against E. coli, Staph. aureus, and Strep. agalactiae. With N. asteroides, the direct plating method gave equivocal results. The filtration experiments indicated that all teat dips containing dodecylbenzene sulfonic acid and nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex were effective against all four pathogens. Three of the teat dips containing chlorhexidine acetate were ineffective against N. asteroides. The fourth teat dip, containing chlorhexidine acetate and an emollient, was partially effective.

Animals↗

PubMed1994

Efficacy of two barrier teat dips containing chlorous acid germicides against experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Two postmilking teat dips were tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae using experimental challenge procedures recommended by the National Mastitis Council. Both dips contained chlorous acid as the primary germicidal agent and lactic acid or mandelic acid as the chlorous acid activator. The dip activated with mandelic acid significantly reduced new IMI by Staph. aureus and Strep. agalactiae. The IMI rate was reduced 68.7% for Staph. aureus and 56.4% for Strep. agalactiae. The dip activated with lactic acid significantly reduced new Staph. aureus IMI by 69.3% but did not significantly reduce new Strep. agalactiae IMI (35.2% reduction) through the full 11-wk study period. Teat skin condition did not change from pretrial status after using either teat dip during the study.

Animals↗

PubMed1997

Evaluation of two iodophor teat germicides: activity against Staphylococcus aureus and Streptococcus agalactiae.

Two germicides containing 0.5 and 1% titratable iodine were tested for efficacy against the development of new intramammary infections (IMI) caused by Staphylococcus aureus and Streptococcus agalactiae. The two trials for postmilking teat dip used a model for experimental challenge that was recommended by the National Mastitis Council. The 0.5% iodine formulation reduced new Staph. aureus IMI by 78.2% and reduced new Strep. agalactiae IMI by 73.2%. The 1% iodine product reduced new Staph. aureus IMI by 43.5% and reduced new Strep. agalactiae IMI by 46.4%. No adverse effects on the condition of teat skin or on teat ends were observed over the course of the trials. At the completion of each trial, the teat skin of dipped quarters was characterized as normal, smooth skin that was free from scales, cracks, or chapping; the teat orifice was characterized as smooth without evidence of irritation.

Animals↗

PubMed1997

Efficacies of teat germicides containing 0.5% chlorhexidine and 1% iodine during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Two germicides, one containing 0.5% chlorhexidine and one containing 1% iodine, were tested for efficacy against new intramammary infections (IMI) caused by Staphylococcus aureus and Streptococcus agalactiae. The model for the experimental challenge in the trials that were designed to test the efficacy of the two postmilking teat dips was recommended by the National Mastitis Council. The 0.5% chlorhexidine product reduced the number of new IMI caused by Staph. aureus by 73.2% and reduced the number of new IMI caused by Strep. agalactiae by 53.9%. The 1% iodine product reduced the number of new IMI caused by Staph. aureus by 75.6% and reduced the number of new IMI caused by Strep. agalactiae by 53.5%. In both trials, the incidence of clinical mastitis was also reduced in dipped quarters compared with control quarters. Use of the two teat dips over the trial periods had no effect on the condition of teat skin or teat ends.

Administration, Topical↗

PubMed1998

Germicidal activity of a chlorous acid-chlorine dioxide teat dip and a sodium chlorite teat dip during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Three postmilking teat dips were tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae in two separate studies using experimental challenge procedures that were recommended by the National Mastitis Council. The first study evaluated a barrier teat dip product containing chlorous acid-chlorine dioxide as the germicidal agent, and the second study evaluated a sodium chlorite product with a barrier component as well as a sodium chlorite product without a barrier component. The chlorous acid-chlorine dioxide teat dip reduced new intramammary infections (IMI) caused by Staph. aureus by 91.5% and reduced new IMI caused by Strep. agalactiae by 71.7%. The barrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus and Strep. agalactiae by 41.0 and 0%, respectively. The nonbarrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus by 65.6% and reduced new IMI caused by Strep. agalactiae by 39.1%. Teat skin and teat end conditions were evaluated before and after the second study; no deleterious effects among dipped quarters compared with control quarters were noted for the two sodium chlorite products.

Animals↗

PubMedDate not supplied

Principles to guide international standard tests for liquid chemical germicides: a proposal.

This review discusses issues involved in developing standard tests for liquid chemical germicides and suggests some guiding principles to be considered for future development of harmonized international standard methods for testing disinfectants and sterilants. A published test method to measure sporicidal activity is used as an example of the implementation of these principles.

Anti-Bacterial Agents↗

PubMed1999

Dosimetry of room-air germicidal (254 nm) radiation using spherical actinometry.

A method is demonstrated for measuring germicidal (254 nm) ultraviolet radiation (GUVR) in an omnidirectional manner. This method has application for those situations in which GUVR from more than one direction or source impinges on a three-dimensional object, and when it is of interest to determine the radiant fluence experienced by the object. For this purpose spherical quartz vessels were constructed varying from 0.8 to 1.25 cm in outside diameter. The vessels were filled with an actinometric solution consisting of KI and KIO3. This solution is optically opaque at 254 nm and is insensitive to room light. Upon exposure to GUVR this solution, which counts all of the 254 nm photons, forms triiodide. Following radiation, the contents of the vessel are removed, the absorbance of triiodide measured and the fluence rate determined based on a relationship that takes the volume to cross-sectional area of the actinometer into account. It is demonstrated that, in accordance with theory, the area of the sphere that intercepts the radiant energy is equal to the cross-sectional area of the sphere. A demonstration of the utility of this method was carried out in a test facility 90 m3 equipped with five GUVR lamps, one in each corner and one in the center of the room, arranged so as to irradiate the air in the upper portion of the room. Twenty spherical actinometers were evenly distributed around the room and exposed for either 30 or 90 min. The fluence rate varied from one part of the room to another, peaking near the GUVR lamps at 65-85 microW per cm2. By averaging over all 20 points, a pseudoaverage fluence rate for the room was found to be 42 and 44 microW per cm2 for the 30 and 90 min exposures, respectively. The similarities in the values for this metric demonstrates that the actinometric response is linear over this exposure range.

Disinfection↗

PubMed2002

Occupational risk from ultraviolet germicidal irradiation (UVGI) lamps.

The recommended role of ultraviolet germicidal irradiation (UVGI) is to reduce the risk of tuberculosis (TB) transmission in health care facilities. However, excess exposure may result in dermatosis and photokeratitis. In one hospital setting in Botswana, two nurses and one housekeeper complained of eye discomfort, 'like sand in the eyes', after working in an administrative office. The following day, one employee noted facial skin peeling. All symptoms resolved over 2-4 days without sequelae. Six weeks later, the syndrome recurred for all three employees. A workplace investigation revealed that the office had been converted from a hospital sputum induction room, and that an unshielded 36-W UVGI lamp was still installed and operational. The on/off switch for the UVGI lamp was immediately adjacent to the fluorescent bulb on/off switch, and did not have a locking mechanism. The US National Institute for Occupational Safety and Health recommends that exposure to UVGI (254 nm) be less than 6000 microJ/cm2 (6000 microW approximately = sec/cm2) over a daily 8-hour period on unprotected skin or eyes. In the office, UVGI measurements at eye level and looking directly at the UVGI lamp ranged from a low of 20.0 microW approximately = sec/cm2 when seated to a high of 49.9 microW approximately = sec/cm2 when standing. These irradiance levels result in allowable exposure times of 300 and 120 seconds, respectively, and are the most likely cause of the clinical syndrome described.

Disinfection↗