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[Characteristics of determining the microbial contamination of penicillin series antibiotic powders and tablets].

Optimal conditions for determination of microbial contamination of drugs were studied on artificially contaminated powders and tablets of phenoxymethylpenicillin, ampicillin, oxacillin and dicloxacillin. The method of membrane filtration was the best for determination of the microbial contamination of the powders. However, it was not possible to wash out completely the antibiotic from the membrane filter. To prevent this it was necessary to add penicillinase into the nutrient medium onto which the filter was put for providing the microbial growth. For determination of microbial contamination of tablets direct plating of 3 per cent suspension of the tablet mass onto the surface of the nutrient medium with penicillinase was the best.

Ampicillin

Significance of microbial contamination of stored cadaver kidneys.

The importance of microbial contamination of cadaver kidneys was assessed in 83 consecutively stored and transplanted kidneys. Fourteen kidneys had a single positive culture during storage and five had multiple positive cultures. Only one postoperative infection could be traced to kidney contamination during storage (Candida wound infection). In three of 64 patients who received noncontaminated kidneys, posttransplant wound infections developed. No wound infections occurred in 35 patients who received prophylactic antibiotics, whereas four wound infections occurred in 48 patients without antibiotic coverage. It is concluded that, although microbial contamination of stored cadaver kidneys occurs commonly, it is not an important source of infection in renal transplant recipients.

Candidiasis

[Microbial contamination of dust in minimum-morbidity housings for pig rearing].

The range of the microbial contamination of 1 g of dust in minimum-morbidity pig rearing houses is from 2.9 . 10(7) to 7.6 . 10(9) in the microbes growing on meat-peptone agar (MPA), from 4.6 . 10(7) to 4.6 . 10(8) in moulds growing on the Czapek-Dox agar, from 1.4 . 10(2) to 7.0 . 10(4) in the total number of microbes growing on End's agar, and from 3.1 . 10(2) to 5.7 . 10(3) in the typically lactose-positive microbes growing on End's agar. The numbers of microbes in 1 g of dust in the conventional pig houses are close to the numbers found in pig rearing houses with minimum morbidity. However, in the moulds on the Czapek-Dox agar, the range of the microbial contamination of dust in the minimum-morbidity pig houses was much higher. The highest level of the contamination of dust with microbes was found on all types of media from houses with continual operation. It was revealed by the control of the effectiveness of disinfection in the minimum-morbidity piglet rearing section, operated on the all-in all-out basis, that in a half of the cases studied the disinfection had low effectiveness. The total number of microbes per 1 sq. cm was lower than required on the basis of research published in literature, but the occurrence rate of positive smears with lactose-positive microbes after disinfection was higher in percentual expression.

Animals

Use of electron microscopy for detection of viral and other microbial contaminants in bovine sera.

A total of 25 lots of bovine serum samples were pelleted in Beem capsules for thin sectioning and were examined by electron microscopy. These included 17 lots of fetal bovine serum pools and five lots of calf serum pools obtained from commercial sources, and three lots of adult bovine serum from local dairy farms. Virus-like particles, 50 to 300 nm in diameter, were detected in 17 of 25 (68%) of the sera. Five of 25 serum samples showed the presence of mycoplasma-like agents. Incubation of bovine serum at 35 C for 1 or 2 weeks appeared to destroy some of these agents, but in certain instances it enhanced bacteria and bacteriophage contaminants. The advantages of electron microscopy using the thin-sectioning technique for detection of microbial contamination in bovine sera are illustrated.

Animals

High levels of microbial contamination of vegetables irrigated with wastewater by the drip method.

The public health aspects of the use of wastewater in agriculture and the effects of the drip irrigation method on the contamination of vegetables were studied. The method used was to simulate enteric microorganisms' dissemination by contaminated irrigation water in the field. The vegetables were irrigated with an effluent inoculated with a high titer of traceable microorganisms: poliovirus vaccine and a drug-resistant Escherichia coli. The dissemination of the marker organisms in the field was followed, and the effects of certain manipulations of the drip irrigation method on the contamination of the crops by the effluent were examined. It was shown that drip irrigation under plastic sheet cover with the drip lines placed either on the soil surface or buried at a depth of 10 cm significantly reduced crop contamination from inoculated irrigation water even when massive doses of bacteria and viruses were used. The microbial contamination was found to persist in the irrigation pipes and in the soil for at least 8 and 18 days, respectively. The data indicate that the recovery of the marker organisms was affected by soil texture and environmental conditions.

Agriculture

Microbial contamination of pharmaceutical products in the home.

One thousand, nine hundred and seventy-seven pharmaceutical products used in the home were examined for microbial contamination. Viable micro-organisms were recovered from 14.0% of samples. Medicines used in the home are apparently not exposed to the same opportunities for contamination as those used in hospital.

Bacteria

[Determination of the microbial contamination of tablets of tetracycline series antibiotics].

The experiments showed that the method of direct plating of tetracycline tablet suspensions on solid nutrient media containing magnesium sulfate may be used for determination of microbial contamination. The method provided determination of both the antibiotic resistant and the antibiotic sensitive organisms which may be present in the drug. Dilution of the basic suspensions increased the probability of the microbe detection in the tablets.

Dose-Response Relationship, Drug

[Tetracycline inactivation by magnesium sulfate in testing for microbial contamination by the membrane filtration method].

It was shown that the residual amounts of tetracyclines adsorbed on membrane filters may be inactivated by addition of 2M magnesium sulphate solution to the agar for placing the filters after filtration. The antibiotic inactivation increases the possibilities of the test for antibiotic sensitivity of the microflora present in the drugs and may be used in determination of microbial dissmination of non-injection tetracyclines.

Adsorption

Prevalence and survival of microbial contaminants in heated nebulizers.

Over a 2-year period, 600 cultures of fluid in heated nebulizers in use by patients in the Peter Bent Brigham Hospital were performed. The most commonly isolated microorganisms were Pseudomonas and Alcaligenes species. Pseudomonas aeruginosa was never isolated. Three types of heated nebulizers were in use, and their contamination rate was significantly different (45 percent, 21 percent, and 8 percent, respectively; p less than 0.001). In the course of the study, the overall contamination rate decreased from 47 percent to 10 percent. This was mainly due to elmination of the type of heated nebulizer that was most prone to contamination. Five types of currently available large-reservoir nebulizers were inculated with various organisms and growth patterns studied. The various nebulizing equiment differed in its ability to inhibit or eliminate microbial growth; 1 of the heated nebulizers appeared to enhance growth of some of the inoculated bacteria.

Acinetobacter

Comparative performance of sponge versus flocked swabs for culture-based and metagenomic detection of microbial contamination in the healthcare environment.

BACKGROUND: Identifying optimal methods for sampling surfaces in the healthcare environment is critical for future research requiring the identification of multidrug-resistant organisms (MDROs) on surfaces. METHODS: We compared 2 swabbing methods, use of a flocked swab versus a sponge-stick, for recovery of MDROs by both culture and recovery of bacterial DNA via quantitative 16S polymerase chain reaction (PCR). This comparison was conducted by assessing swab performance in a longitudinal survey of MDRO contamination in hospital rooms. Additionally, a laboratory-prepared surface was also used to compare the recovery of each swab type with a matching surface area. RESULTS: Sponge-sticks were superior to flocked swabs for culture-based recovery of MDROs, with a sensitivity of 80% compared to 58%. Similarly, sponge-sticks demonstrated greater recovery of Staphylococcus aureus from laboratory-prepared surfaces, although the performance of flocked swabs improved when premoistened. In contrast, recovery of bacterial DNA via quantitative 16S PCR was greater with flocked swabs by an average of 3 log copies per specimen. CONCLUSIONS: The optimal swabbing method of environmental surfaces differs by method of analysis. Sponge-sticks were superior to flocked swabs for culture-based detection of bacteria but inferior for recovery of bacterial DNA.

Humans

Microbial contamination of topical medicaments used in the treatment and prevention of pressure sores.

Topical medicaments used in the treatment and prevention of pressure sores in patients in three hospitals were examined for Pseudomonas aeruginosa and Staphylococcus aureus contamination. Contamination rates were found to vary between hospitals and were affected by differences in the packaging of the product and in the method of application used by the nursing staff.

Administration, Topical

Rapid detection of microbial contamination in frozen vegetables by automated impedance measurements.

Automated impedance measurements can be used to rapidly assess whether a sample of frozen vegetables contains greater or less than 10(5) organisms per g. Microorganisms growing pureed food samples cause a change in the impedance of the medium when the organisms reach a threshold concentration of between 10(6) and 10(7) organisms per ml. Estimates of the concentration of microorganisms initially present in the food sample can be made by recording the time required for the organisms in the sample to replicate to threshold levels. In this study, the detection times for 357 samples of frozen vegetables were compared with standard plate counts for each sample. The agreement between the two methods in distinguishing samples containing more than 10(5) organisms per g was 92.6% for 257 assorted frozen vegetables and somewhat higher (93 to 96%) when separate cutoff times were used for each type of vegetable. The time required for analysis was about 5 h, compared to the 48 to 72 h required for standard plate counts.

Bacteria