Biomedical subjects

C M Herring

Publications and source records attributed to C M Herring.

7 recordsLinked to original sources

PubMed1986

In vivo study of an antimicrobial surgical drape system.

We performed a double-blind clinical study to determine the efficacy of nonwoven laparotomy drapes in which 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride, an antimicrobial agent, was chemically bonded to the absorbent reinforcement surrounding the fenestration. The reinforcement portion of the surgical drape that contained the fenestration was segmented into four identical-appearing sections, two on each side of the fenestration. One segment on each side was antimicrobial. The locations of the treated segments were randomly varied. At the end of each operation, test strips were removed. Bacteria were harvested from each segment by mechanical agitation. Bacterial CFU were counted. There were 110 surgical cases in the study, including clean, clean contaminated, and contaminated procedures. Data analysis divided the cases into two distinct groups. Group 1 was composed of 59 cases in which less than 30 total CFU was recovered from the four test samples. The average duration of surgery for this group was 1.8 h. Group 2 was composed of 51 cases in which bacterial recovery was in excess of 30 CFU per procedure (range, 30 to 25,000 bacterial CFU). The average duration of surgery was 3.3 h. Bacterial reduction in the treated strips was 84%. The most common organisms identified on the laparotomy drapes were Staphylococcus epidermidis, S. hominis, and Micrococcus luteus. This study demonstrated that the reinforcement of a laparotomy drape is a reservoir for potential pathogens. It demonstrated that an organosilicon quaternary ammonium antimicrobial agent covalently bonded to the reinforcement reduced the number of potential pathogens surrounding the surgical incision by 84%, independent of the size of the bacterial challenge.

Anti-Infective Agents, Local↗

PubMed1975

Isolation of Penicillium corylophium Dierckx from acid mine water and its optimal growth on hydrocarbons at acid pH.

Penicillium corylophilium Dieckx was isolated from sludge collected at the interface of an aqueous, copper-bearing leachate and an organic, kerosene based, ion exchange solvent. The organism assimilated kerosene and various straight chain and cyclic hydrocarbons including dodecane, hexadecane, octadecane, toluene, benzene, and cyclohexane. Assimilation of kerosene and hexadecane was optimal at pH 2 and was stimulated by yeast extract.

Copper↗

PubMed1975

Method for collecting naturally occurring airborne bacterial spores for determining their thermal resistance.

The ability to determine the thermal resistance of naturally occurring airborne bacterial spores associated with spacecraft and their assembly areas has been hindered by lack of an effective collecting system. Efforts to collect and concentrate spores with air samplers or from air filters have not been successful. A fallout method was developed for this purpose and tested. Sterile Teflon ribbons (7.6 by 183 cm) were exposed in pertinent spacecraft assembly areas and subsequently treated with dry heat. Thermal inactivation experiments were conducted at 125 and 113 C. Heating intervals ranged from 1 to 12 h at 125 C and 6, 12, 18, and 24 h at 113 C. Eight hours was the longest heating time yielding survivors at 125 C, whereas survivors were recovered at all of the heating intervals at 113 C. D125C values were calculated using the fractional-replicate-unit-negative technique of Pflug and Schmidt (1968) and ranged from 25 to 126 min. This variation indicated that the most probable number of survivors at each heating interval did not fall on a straight line passing through the initial spore population. However, the most-probable-number values taken alone formed a straight line suggesting logarithmic thermal destruction of a subpopulation of spores with a D125C value of 6.3 h.

Air Microbiology↗

PubMed1975

Quantitative relationship between airborne viable and total particles.

The numbers of viable and total particles in a microbiological laboratory and in a class 100,000 clean room were examined for a predictable relationship to aid the monitoring of airborne microbial contamination. Six-stage Andersen samplers were used to enumerate viable particles and a modified Royco particle counter was used to enumerate total particles. Over 99% of the total particles present in both areas were less than 1 micron in size; however, only 1 in 10,000 of the particles this size were viable. At the other end of the particle size scale, it was found that less than 0.1% of the total particles were greater than 5.4 micron in size, but only 4.5% of these particles were viable. Viable particles make up only a very small portion of the total particles making any correlation undetectable. An analysis of the combined data from both areas using only total and viable particles over 5.4 micron showed a positive correlation. An analysis of the data from each area individually showed no correlation. Estimation of viable particulates from enumeration of total particulates in the large particle ranges may be possible only in areas where a high degree of environmental control is exercised.

Air Microbiology↗

PubMed1974

Evaluation fo membrane filter field monitors for microbiological air sampling.

Due to area constraints encountered in assembly and testing areas of spacecraft, the membrane filter field monitor (MF) and the National Aeronautics and Space Administration-accepted Reyniers slit air sampler were compared for recovery of airborne microbial contamination. The intramural air in a microbiological laboratory area and a clean room environment used for the assembly and testing of the Apollo spacecraft was studied. A significantly higher number of microorganisms was recovered by the Reyniers sampler. A high degree of consistency between the two sampling methods was shown by a regression analysis, with a correlation coefficient of 0.93. The MF samplers detected 79% of the concentration measured by the Reyniers slit samplers. The types of microorganisms identified from both sampling methods were similar. Variables in the MF samplers, such as pore size, relative humidity, and flow rates, have been studied, but no effect was noted on recovery. The results show that the MF method could be used to estimate the number and types of microorganisms found in the air.

Actinomycetales↗

PubMed1974

Comparison of media for detection of fungi on spacecraft.

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay.

Agar↗

PubMed1973

Microbiological profiles of four Apollo spacecraft.

Selected surfaces from the Command Module, Lunar Module (ascent and descent stages), Instrument Unit, Saturn S-4B engine, and Spacecraft Lunar Module Adapter comprised the various components of four Apollo spacecraft which were assayed quantitatively and qualitatively for microorganisms. In addition, the first Lunar Roving Vehicle was assayed. Average levels of microbial contamination (10(4) per square foot of surface) on the Command Module, Instrument Unit, and Saturn S-4B engine were relatively consistent among spacecraft. The first postflight sampling of interior surfaces of the Command Module was possible due to elimination of the 21-day back-contamination quarantine period. Results of the pre- and postflight samples revealed increases in the postflight samples of 3 logs/inch(2). A total of 5,862 microbial isolates was identified; 183 and 327 were obtained from the Command Module at preflight and postflight sampling periods, respectively. Although the results showed that the majority of microorganisms isolated were those considered to be indigenous to humans, an increase in organisms associated with soil and dust was noted with each successive Apollo spacecraft.

Actinomycetales↗