Bacterial contamination of platelet concentrates (PCs) represents the highest post-transfusion infectious risk. The skin flora bacterium Staphylococcus epidermidis has been reported to be the predominant aerobic contaminant of PCs. The Ramirez' group has shown that S. epidermidis can form surface-attached bacterial aggregates known as biofilms, and can outcompete other coagulase-negative staphylococci, such as Staphylococcus capitis, in PCs. The ability of S. epidermidis to form biofilms has been linked to increased pathogenicity and missed detection during PC screening with an automated culture system (BacT/ALERT). This thesis aimed at investigating the proliferative advantage and resistance mechanisms displayed by S. epidermidis in the PC milieu. Furthermore, in an effort to enhance PC safety for transfusion patients, I studied the anti-biofilm properties of essential oils and antimicrobial peptides (AMPs). My studies aimed at improving PC safety by focussing on both the point of introduction of bacterial contaminants (blood collection), and the stage at which bacterial contaminants can form biofilms and proliferate (PC storage). S. epidermidis can be found in the skin of blood donors as biofilms, which are resistant to the blood donor skin disinfectant currently used by Canadian Blood Services, chlorhexidine-gluconate and isopropyl alcohol (CHG-IPA). Here, several plant-extracted essential oils were evaluated for their ability to enhance the anti-biofilm activity of CHG-IPA. Data revealed that the Lavandula multifida oil and its main component (linalool) greatly enhanced the activity of CHG-IPA against S. epidermidis biofilms. Furthermore, the ability of a combination of three synthetic AMPs to inhibit S. epidermidis biofilm formation during PC storage was assessed These results showed that the combination of AMPs could inhibit biofilm formation but was ineffective against pre-formed S. epidermidis biofilms. The accumulation associated protein (Aap) encoded by the aap gene, found in most S. epidermidis strains and absent in S. capitis, plays a role in biofilm formation. When S. epidermidis aap is transformed into S. capitis, this bacterium displayed increased biofilm formation and proliferated to higher concentrations compared to untransformed S. capitis and to a S. epidermidis aap deletion mutant. Based on these results, aap appears to play a role in providing S. epidermidis a proliferative advantage in PCs by enhancing biofilm formation. Lastly, the GraRS system and SepA were studied for their role in S. epidermidis resistance to platelet-derived AMPs using the synthetic AMP PD4 as a model molecule. Results indicate that the GraS mechanism is involved in resistance towards PD4. The work presented in my thesis provides further insights into why S. epidermidis has a proliferative advantage in the PC storage environment and allows for the proposal of alternative methods to enhance PC safety for transfusion patients.

No presente foi avaliado a atividade antimicrobiana de duas técnicas de antissepsia cutânea utilizadas rotineiramente em doadores de sangue em um serviço de Hemoterapia na cidade de Ribeirão Preto. Esse estudo teve como objetivo principal, estabelecer e comparar o percentual de redução microbiana em 50 doadores de sangue antes e após a aplicação de duas técnicas de antissepsia cutânea. Em cada braço do doador foi aplicado uma técnica de antissepsia, na primeira técnica utilizou-se o Polivinilpirrolidona-iodo (PVPI) degermante a 10% em movimentos de descida e subida por 30 segundos combinado com o PVPI a 10% em movimento circular único do centro para a periferia aplicados 30 segundos antes da punção venosa. Na segunda técnica foi utilizada solução de digluconato de clorexidina alcoólica a 0,5% em movimentos de descida e subida por 30 segundos e esperado secar por mais 30 segundos para a posterior punção venosa. Foram coletados swabs cutâneos no local da punção antes e após a aplicação de ambas as técnicas de antissepsia. Os swabs foram semeados em meio de cultura Ágar Sangue, Ágar Manitol Salgado e Ágar Mac Conkey e colocados em estufa à 37ºC por um período de 48 horas. Após esse período, foi realizada a contagem das colônias que cresceram nos meios de cultura. A técnica com PVPI a 10% obteve um percentual médio de redução microbiana de 98,57% no meio de cultura Ágar Sangue, 98,87% no meio de cultura Ágar Manitol Salgado e 100% no meio Mac Conkey. Já a técnica com clorexidina a 0,5% obteve percentual médio de redução microbiana de 94,38% no meio de cultura Ágar Sangue, 95,06% no meio Ágar Manitol Salgado e 100% no meio de cultura Mac Conkey. As análises estatísticas evidenciam que a técnica com PVPI a 10% obteve maior redução microbiana, sendo considerada, no presente estudo, mais eficaz que a Técnica com clorexidina a 0,5%. / In this study were evaluated the antimicrobial activity of two technique of skin antisepsis routinely used in blood donors in a transfusion service in the city of Ribeirão Preto. This study had as main objective, to determine and compare the percentage of bacterial reduction in 50 blood donors before and after application of two methods of skin antisepsis. In each arm of the donor was applied a technique of antisepsis, the first technique used the Polyvinylpyrrolidone-iodine (PVPI) degermant 10% in ascending and descending movements for 30 seconds combined with PVPI alcohol 10% in one circular motion from center to periphery applied 30 seconds prior to venipuncture. The second technique was used chlorhexidine gluconate solution 0.5% alcohol in ascending and descending movements for 30 seconds and waited for another 30 seconds to dry for later venipuncture. Skin swabs were collected at the puncture site before and after application of both techniques of antisepsis. The swabs were seeded in culture Blood Agar, Mannitol Salt Agar and MacConkey agar and placed in an oven at 37°C for a period of 48 hours. After this period, counts were performed in the colonies that grew in culture. The technique with PVPI 10% had an average rate of microbial reduction of 98.57% in the culture medium Blood Agar, 98.87% in the culture medium Mannitol Salt Agar and 100% in Mac Conkey medium. Since the technique with chlorhexidine 0.5% Total average percentage of bacterial reduction of 94.38% in the culture medium Blood Agar, 95.06% in the middle Salt Mannitol Agar and 100% in Mac Conkey medium. Statistical analysis showed that the technique with PVPI 10% was greater than bacterial reduction being considered in the present study, the most effective technique with chlorhexidine 0.5%.

No presente foi avaliado a atividade antimicrobiana de duas técnicas de antissepsia cutânea utilizadas rotineiramente em doadores de sangue em um serviço de Hemoterapia na cidade de Ribeirão Preto. Esse estudo teve como objetivo principal, estabelecer e comparar o percentual de redução microbiana em 50 doadores de sangue antes e após a aplicação de duas técnicas de antissepsia cutânea. Em cada braço do doador foi aplicado uma técnica de antissepsia, na primeira técnica utilizou-se o Polivinilpirrolidona-iodo (PVPI) degermante a 10% em movimentos de descida e subida por 30 segundos combinado com o PVPI a 10% em movimento circular único do centro para a periferia aplicados 30 segundos antes da punção venosa. Na segunda técnica foi utilizada solução de digluconato de clorexidina alcoólica a 0,5% em movimentos de descida e subida por 30 segundos e esperado secar por mais 30 segundos para a posterior punção venosa. Foram coletados swabs cutâneos no local da punção antes e após a aplicação de ambas as técnicas de antissepsia. Os swabs foram semeados em meio de cultura Ágar Sangue, Ágar Manitol Salgado e Ágar Mac Conkey e colocados em estufa à 37ºC por um período de 48 horas. Após esse período, foi realizada a contagem das colônias que cresceram nos meios de cultura. A técnica com PVPI a 10% obteve um percentual médio de redução microbiana de 98,57% no meio de cultura Ágar Sangue, 98,87% no meio de cultura Ágar Manitol Salgado e 100% no meio Mac Conkey. Já a técnica com clorexidina a 0,5% obteve percentual médio de redução microbiana de 94,38% no meio de cultura Ágar Sangue, 95,06% no meio Ágar Manitol Salgado e 100% no meio de cultura Mac Conkey. As análises estatísticas evidenciam que a técnica com PVPI a 10% obteve maior redução microbiana, sendo considerada, no presente estudo, mais eficaz que a Técnica com clorexidina a 0,5%. / In this study were evaluated the antimicrobial activity of two technique of skin antisepsis routinely used in blood donors in a transfusion service in the city of Ribeirão Preto. This study had as main objective, to determine and compare the percentage of bacterial reduction in 50 blood donors before and after application of two methods of skin antisepsis. In each arm of the donor was applied a technique of antisepsis, the first technique used the Polyvinylpyrrolidone-iodine (PVPI) degermant 10% in ascending and descending movements for 30 seconds combined with PVPI alcohol 10% in one circular motion from center to periphery applied 30 seconds prior to venipuncture. The second technique was used chlorhexidine gluconate solution 0.5% alcohol in ascending and descending movements for 30 seconds and waited for another 30 seconds to dry for later venipuncture. Skin swabs were collected at the puncture site before and after application of both techniques of antisepsis. The swabs were seeded in culture Blood Agar, Mannitol Salt Agar and MacConkey agar and placed in an oven at 37°C for a period of 48 hours. After this period, counts were performed in the colonies that grew in culture. The technique with PVPI 10% had an average rate of microbial reduction of 98.57% in the culture medium Blood Agar, 98.87% in the culture medium Mannitol Salt Agar and 100% in Mac Conkey medium. Since the technique with chlorhexidine 0.5% Total average percentage of bacterial reduction of 94.38% in the culture medium Blood Agar, 95.06% in the middle Salt Mannitol Agar and 100% in Mac Conkey medium. Statistical analysis showed that the technique with PVPI 10% was greater than bacterial reduction being considered in the present study, the most effective technique with chlorhexidine 0.5%.

Surgical site infection is a major postoperative complication that causes patient suffering and is costly for society. The general aim of this thesis was to test and describe interventions performed by operating room (OR) nurses to prevent bacterial growth in surgical patients, with the intent to prevent surgical site infections (SSIs) whilst increase patients comfort. In studies I and II, 220 pacemaker patients were tested to compare pre-heated skin disinfection with room-temperature skin disinfection regard-ing bacterial growth, skin temperature and patient experience. Preheated skin disinfection was not less effective compared to room-temperature skin disinfection in reducing bacterial growth after skin disinfection and there were no differences regarding SSIs three month postoperatively. Preheated skin disinfection reduces skin heat loss and was perceived as more pleas-ant compared to room-temperature skin disinfection. In study III, 12 OR nurses were examined regarding bacterial growth on their hands and at the sterile glove cuff end after surgical hand disinfec-tion and again after wearing sterile surgical gloves during surgery. They were compared with a control group of 13 non-health care workers. OR nurses’ hands had higher amounts of bacterial growth at two of three culture sites after surgical hand disinfection compared with the control group, and the bacterial growth increased in both groups with time during surgery. There seems to be a risk of bacterial growth at the glove cuff end during surgery, involving the same type of bacteria as isolated from the hands. In study IV, 890 OR nurses answered an online questionnaire describ-ing OR nurses interventions guided by national guidelines to reduce SSIs, such as preparation of the patient skin, patient temperature, and OR ma-terials used. The proportion of the OR nurses who complied with the national guidelines preventive interventions was high: skin disinfection solution (93.5%), drapes (97.4%) and gowns (83.8%), and double gloves (73%). However, when guidelines were lacking the interventions differed.

Alla patienter som genomgår någon typ av operation där man penetrerar huden har en ökad risk att drabbas av en postoperativ sårinfektion.Syftet var att utforska de preoperativa åtgärderna huddesinfektion och hårborttagning relaterat till uppkomsten av postoperativa sårinfektioner.Metoden var en systematisk litteratur studie där nio artiklar användes som underlag.Resultatet visade att klorhexidin reducerar bakterierna på huden, men ingen signifikant minskning av antalet postoperativa sårinfektioner kunde påvisas. Av hårborttagningsmetoderna rakhyvel, rakapparat och hårborttagningskräm ger rakhyvel upphov till fler små sår. / All patients going through any type of surgery where the skin will be penetrated have an increased risk to be afflicted to a postoperative wound infection. The aim of this study was to explore the preoperative preventions skin disinfections and hair removal related to development of postoperative wound infection. This literature review was based on nine articles. The results showed that chlorhexidine do reduce the incidence of bacteria on the skin but no significant reduction of postoperative wound infections was proved. Between the hair removal methods shaving with razor, electric clipper and depilatory the razor cause more cuts on the skin.