Refrigerated multi-dose insulin vials remain sterile through 6 months of use

OBJECTIVES

To evaluate sterility in refrigerated multi-dose insulin vials through 6 months of routine aspiration.

MATERIALS AND METHODS

Twelve vials of insulin, six of insulin glargine U100 (Lantus®, 10 mL multi-dose vial, Sanofi, Bridgewater, NJ) containing the preservative metacresol, and six of protamine zinc insulin U40 (ProZinc®, 10 mL multi-dose vial, Boehringer Ingelheim, Duluth, GA) containing the preservative phenol, were refrigerated and aspirated twice daily for 6 months, using a new insulin syringe each time. Three vials of each insulin type were wiped with a single-use alcohol swab before sampling. Three times weekly, aspirated samples were inoculated in Tryptic Soy Broth enrichment media and incubated for evidence of microbial growth. Positive broth was cultured and speciated. Endpoints were microbial vial contamination (defined as three consecutive positive cultures of the same organism) and completion of the six-month study period.

RESULTS

Microbial contamination was not identified in any vial throughout the study period. A total of 454 aspirated samples were cultured, one of which exhibited non-repeatable growth of Staphylococcus epidermidis. This vial was prematurely lost to breakage after 59 culture samples (29 after the positive growth).

CLINICAL SIGNIFICANCE

Refrigerated phenol- and metacresol-containing multi-dose insulin products carry minimal risk for iatrogenic infection through 6 months of use, regardless of alcohol swab preparation.

Sorption dynamics of organic and inorganic phosphorus compounds in soil

Phosphorus retention in soils is influenced by the form of P added. The potential impact of one P compound on the sorption of other P compounds in soils has not been widely reported. Sorption isotherms were utilized to quantify P retention by benchmark soils from Indiana, Missouri, and North Carolina when P was added as inorganic P (Pi) or organic P (beta-D-glucose-6-phosphate, G6P; adenosine 5'-triphosphate, ATP; and myoinositol hexaphosphate, IP6) and to determine whether soil P sorption by these organic P compounds and Pi was competitive. Isotherm supernatants were analyzed for pH and total P using standard protocols, while Pi and organic P compounds were assayed using ion chromatography. Under the controlled conditions of this study, the affinity of all soils for P sources followed the order IP6 > G6P > ATP > Pi. Each organic P source had a different potential to desorb Pi from soils, and the order of greatest to least Pi desorption was G6P > ATP > IP6. Glucose-6-phosphate and ATP competed more directly with Pi for sorption sites than IP6 at greater rates of P addition, but at the lesser rates of P addition, IP6 actually desorbed more Pi. Inositol hexaphosphate was strongly sorbed by all three soils and was relatively unaffected by the presence of other P sources. Decreased total P sorption due to desorption of Pi can be caused by relatively small additions of organic P, which may help explain vertical P movement in manured soils. Sorption isotherms performed using Pi alone did not accurately predict total P sorption in soils.

Occupational asthma prevention and management in industry--an example of a global programme

Isocyanates are widely used in the manufacture of polyurethane foams, plastics, coatings and adhesives, and are known to cause occupational asthma in a proportion of exposed workers. Substitution as a prevention strategy is not currently a feasible option. For this reason, health and safety professionals working together in an automotive coatings business created a proactive global programme to address the known potential effects of isocyanates on its workers. The goals of the programme are prevention, early detection and mitigation of effect of key endpoints, especially asthma and to a lesser degree dermatitis, in people who are occupationally exposed, or potentially exposed, to isocyanates and products containing isocyanates. The surveillance programme for isocyanates has several important components, which include assessment of exposure, pre-placement questionnaire and spirometry, training and education of employees, regularly administered periodic questionnaires, medical assessment for abnormal questionnaire responses, process for early reporting and investigation of symptomatic employees and incidents, group data review and management reporting. Although regional differences exist regarding availability of specialized services, we have successfully implemented this programme in parts of North America, Europe and Latin America, and are currently implementing elsewhere. These simple control measures are relatively inexpensive and can be applied in even small business settings. It is recommended that all employers who manufacture, handle or use isocyanate-containing products consider such a strategy.