Inoculation Of Culture Medium Research Articles

654 Investigation of Germ Patency of a Polylactic Acid-based Membrane for the Treatment of Burns

Abstract Introduction Infections are a very serious complication during the treatment of burns. To avoid such infections, burn care dressings and skin substitutes should be impermeable to germs. Polylactic membranes (PLM) are based on polylactic acid (PLA) and as an elastic membrane it mimics the natural skin. They are indicated for superficial (2a°) and deep dermal/partial thickness (2b°) skin loss diseases like burns. While being permeable to oxygen and water vapor, they provide a physical barrier for microorganisms. The infection rate of the PLM in burns was about 2,9% on average and was published in 11 studies. The effectiveness of the physical barrier for microorganism was tested in an in-vitro model. Methods The sterile PLM samples were aseptically transferred into sterile petri dishes and inoculated with 100 µl each of a bacterial suspension. The test strains Staphylococcus aureus (ATCC 6538) with approximately 730 colony forming units (cfu) and Pseudomonas aeruginosa (ATCC 10145) with approximately 350 CFU / sample were used. The bacterial suspension was spread over the surface and dried. PLM were transferred to Tryptic Soy Agar (TSA) plates. The incubation was carried out in each case with 3 batches per test strain after 1 day and 3 days at 37°C. After incubation, the PLM samples were visually examined for microbial growth under the samples and photographically documented. A control group with inoculation of culture medium and covered with PLM was also tested. Results There was no growth of bacteria detectable after 1 day and after 3 days under the PLM indicating that the PLM is not permeable to germs. The control group resulted in growth of bacteria and colony forming units and thus confirms that test method works well. Conclusions PLM is an effective physical barrier for microorganisms as germs do not pass the PLM. Applicability of Research to Practice immediately.

Cross-sectional study of the microbiological safety profile of reusing hyaluronic acid fillers.

Facial filling with hyaluronic acid (HA) is a dermatological procedure that has been emerging today. There are not many references regarding safety of reusing the remaining product for later touch-up in the same patient. To determine the microbiological safety of reusing hyaluronic acid that is remnant from syringes used for facial filling, stored at room temperature or cooled in a refrigerator at 4°C. In culture medium, small aliquots of leftovers from 31 hyaluronic acid fillers, previously used for facial filling, were inoculated. The fillers were stored in their original syringes at room temperature or cooled in a standard refrigerator at 4°C for a period ranging from 1 week to 12 months after initial use. The small number of samples limits extrapolation of the results obtained. After 42 days of inoculation in culture medium, none of the samples showed any aerobic or anaerobic bacterial or fungal growth. Hyaluronic acid fillers did not show any fungal or bacterial contamination after being opened and stored at room temperature in nonaseptic conditions. The possibility of reusing the remaining portion of the material in the syringe can be safe and economically viable.

Delayed versus immediate inoculation of culture media for diagnosis of urinary tract infection

Delayed versus immediate inoculation of culture media for diagnosis of urinary tract infection

Adequação de nutrientes do meio MT para o cultivo de embriões imaturos de tangerineira 'Cleópatra'

Este trabalho teve como objetivo ajustar a concentração de macronutrientes, micronutrientes e vitaminas do meio de cultura Murashige & Tucker (MT), de modo a permitir a germinação de embriões imaturos, menores que 3 mm, de tangerineira 'Cleópatra'. As sementes foram obtidas a partir de frutos com 4 a 5 meses após a antese, cujos embriões não germinam nos meios de cultura atualmente indicados para citros. Inicialmente, os embriões foram cultivados em meio de cultura básico contendo sacarose e ágar, seguindo uma seqüência de etapas, procedendo-se a ajustes da concentração normal dos macronutrientes (1/1, ½ e ¼), micronutrientes (1/1, ½, ¼ e 1/1, 3/2, 2/1) e vitaminas (2/1, 1/1 e ½) do meio MT. O delineamento experimental foi inteiramente casualizado, em um esquema fatorial 3 (concentrações do MT) x 4 (comprimentos de embriões), com 10 repetições. As variáveis, porcentagem de germinação de embriões, porcentagem de plântulas normais e comprimentos dessas plântulas foram avaliadas 30 dias após a inoculação dos embriões em meio de cultura. Os melhores resultados foram obtidos utilizando-se de metade da concentração normal de macronutrientes, não havendo necessidade de alterar as concentrações de micronutrientes e vitaminas.

Transmission of Leishmania infantum via blood transfusion in dogs: Potential for infection and importance of clinical factors

Blood transfusion is an important routine practice in veterinary medicine that generally involves the use of whole blood. Permanent blood donors must be vaccinated against viral infections that affect dogs and submitted periodically to clinical and serological examinations to detect blood-transmitted diseases. There is a very high risk of transmission of infectious agents, particularly protozoans due to their long incubation periods, subclinical persistence in infected animals and likelihood of remaining viable in bloodstocks. The aim of the present study was to identify the potential of asymptomatic and oligosymptomatic dogs for Leishmania infantum transmission as a result of transfusional practice. Nineteen Leishmania-seropositive adult dogs of both sexes and indeterminate breeds were selected as donors. The animals were classified as symptomatic, oligosymptomatic or asymptomatic after clinical examination and evaluated by ELISA, IFAT and bone marrow puncture biopsies. Whole blood and monocyte cells were collected and used for dog's serological evaluation and inoculation in culture medium as well as in hamsters. All but three dogs were positive for IFAT, ELISA and parasite demonstration in bone marrow aspirates, irrespective of their clinical conditions. Parasites were detected in 77% of the whole blood and 90% of the monocyte cultures. Six months after inoculation with whole blood or monocytes, hamsters developed infection and clinical symptoms of visceral leishmaniasis, as well as positive titres measured by ELISA. These results suggest that blood donors should be monitored periodically and rigorously for Leishmania infection, to prevent dissemination of the disease through blood transfusion.

Absence of infectious retinitis after injection of human cytomegalovirus into rabbit eyes.

The rabbit model of human cytomegalovirus (HCMV) retinitis was evaluated by preretinal and intravitreal injection of HCMV into rabbit eyes. Ocular disease was evaluated by indirect ophthalmoscopy, histopathology, and immunohistochemistry. Vitritis, optic nerve congestion, multiple small white infiltrates in the cortical vitreous or on the retinal surface, and retinal detachments were seen. Histopathologic examination showed inflammatory cell infiltration in the preretinal vitreous, optic nerve, and transiently in the superficial inner retina. Retinal structure was preserved except for changes in areas of retinal detachment. No necrosis or destruction of the retina was seen. Immunohistochemistry showed no evidence of cytomegalovirus infection. Inoculation of culture medium containing fetal calf serum caused a similar reaction. It is concluded that vitreous and retinal inoculation of HCMV in the rabbit eye caused nonspecific inflammation without evidence of infection, so this is not a suitable model for HCMV retinitis.

Cutaneous Leishmaniasis in Guatemala: Comparison of Diagnostic Methods

A comparison was made of methods used to diagnose suspected cutaneous leishmaniasis in Guatemala. The most sensitive method was a combination of thin smears made from superficial scrapings of the ulcers and inoculation of culture medium with either aspirates or scrapings. The diagnosis was confirmed in 252 (70%) of 362 patients. Ability to cultivate Leishmania was correlated with the concentration of amastigotes seen on thin smears. Leishmania were cultured in 42 (27%) of 153 patients with no amastigotes found in 400 oil-immersion fields and in 174 (83%) of 209 patients with at least 1 amastigote. No difference in diagnostic outcome was found when we compared smears or cultures taken from the center or the border of the ulcer or from an incision made tangential from the ulcer. We found no difference when we compared smears obtained with scalpels, capillary tubes, or dental broaches. The use of scrub brushes soaked in iodine neither decreased the rate of culturing parasites nor decreased contamination rates.

Growth and sporulation in vitro of Cercospora apii, Cercospora arachidicola, Cercospora kikuchii, and other species of Cercospora

Cercospora apii Fres., Cercospora arachidicola Hori, and Cercospora kikuchii (Matsumoto & Tomoyasu) Gardn. were single spored, and the resultant colonies were characterized. All isolates of C. arachidicola were morphologically identical, whereas those of C. apii and C. kikuchii were either smooth or had radial folds. Variability in sporulation was also evident. Multiple-point inoculation of culture media in plates with conidia helped to overcome variability in the amount of conidial production. Maximum sporulation was obtained at 4 days with C. apii and C. kikuchii, and from 7 to 10 days with C. arachidicola. Single-point inoculation of a V-8 culture medium in plates from peripheral dark mycelial growth in potato dextrose agar (PDA) culture resulted in increased sporulation by C. kikuchii. Sporulation of C. kikuchii was maintained throughout a 15-month study by selective subculturing; however, conidial production decreased over time. A total of 15 other species of Cercospora sporulated within a week following a V-8 inoculation of culture medium in plates with mycelial agar blocks.

Trypanosomes of the Lesser Anteater, Tamandua tetradactyla, from Panama

Seventeen anteaters (Tamandua tetradactyla) from Panama were examined by blood examination and culture for trypanosomes. Eight of these exhibited trypanosomes, four of which were dual infections with more than one species. T. legeri, a little-known species not previously reported from Panama, was found in five animals and established in vitro culture for the first time. Observations concerning the biology of this species, as well as its biometric characterization based on a much larger number of parasites than has heretofore been available, are reported. The most prevalent species was T. rangeli, found in six animals. One infection with a T. cruzi-like trypanosome was encountered. In 1910, Mesnil and Brimont described Trypanosoma legeri from an anteater, Tamandua tridactyla, from French Guiana which was quite different from all other mammalian trypanosomes known at that time. Because of the broad form and highly convoluted undulating membrane it was said to resemble a bird trypanosome more than a mammalian parasite. In addition, it possessed a distinctive character in that the free flagellum terminated in a knoblike enlargement. This terminal granule stained a deep violet color with Giemsa's stain, and was said to be always present. The measurements given for this trypanosome were 42 to 45 Kt in total length and 5 to 6.5 t in width. Published references to this parasite subsequent to the original description have been rare. In 1926, Strong et al. reported its occurrence in Tamandua tetradactyla in Brazil, and this observation was repeated by Deane (1961). Lainson (1965) found five infected T. tetradactyla in British Honduras. The only report of this parasite in a host other than an anteater is that of Trejos and Montero-Gei (1953) who identified as T. legeri a trypanosome encountered in the blood of a sloth, Bradypus griseus, from Costa Rica. Other than to extend the known geographic and host range, these investigators were able to contribute little to the knowledge of this parasite. The natural vector has remained unknown, and no success in infection of laboratory animals has been achieved, nor has it been established in culture, although Strong et al. Received for publication 5 May 1967. * Lieutenant Colonel MSC USA. (1926), Deane (1961), and Lainson (1965) reported attempts to do so. Two other species of trypanosomes have been described from similar hosts: T. myrmecophagae from Tamandua tridactyla in French Guiana by Floch et al. (1941, 1949) and T. mesnil-brimonti from the sloth Choloepus didactylus in Brazil by Deane (1961). From 1963 to 1965 we have observed this trypanosome in the blood of five Tamandua tetradactyla from Panama and successfully established it in in vitro culture. A preliminary report of some of these observations was given at the Third Latin American Congress of Microbiology (Walton and Sousa, 1964). This report will present additional information regarding its distribution and prevalence in Panama, observations regarding its biology, and a biometric characterization of this species based upon a much larger number of parasites than has heretofore been available. MATERIALS AND METHODS A total of 17 adult anteaters were examined by use of fresh blood films and inoculation of culture media. Most of these were livetrapped and bled by cardiac puncture under anesthesia; however, two which had been killed by automobiles on the highway were bled shortly after death. An additional two animals killed in this manner had the thorax crushed so that uncontaminated cultures could not be obtained and only blood smears were examined. The culture media used were bloodagar base (Difco) with 20% defibrinated rabbit blood, with 20% outdated human blood-bank blood, with 10% oxalated sheep blood, and a modified Leishmania Agar medium of Senekjie (Kirby 1950) prepared with 15%, 20%, and 30% rabbit blood. Most cultures were incubated through 28 days