Transmissão de patógenos nosocomiais pelo jaleco branco: um modelo in-vitro
19 de abril de 2010 6 Comentários
Transmissão de patógenos nosocomiais pelo jaleco branco: um modelo in-vitro
Diversos estudos documentam que as roupas dos trabalhadores dos serviços de saúde podem se tornar contaminados com patógenos nosocomiais, os quais podem permanecer viáveis em tecidos por um longo período de tempo. Jalecos brancos geralmente não são lavados diariamente e não podem ser descontaminados entre os atendimentos aos pacientes. (…) O objetivo desse estudo é determinar o quanto organismos multi-resistentes podem ser transferidos do jaleco branco para a pele humana em um modelo de estudo in-vitro. (…)
Nossos dados mostram o potencial de espalhar Staphylococcus aureus resistente a meticilina (MRSA), Enterococcus faecium resistente à vancomicina (VRE) e Acinetobacter baumanni pan resistente (PRA) através de jalecos brancos contaminados é real. Enquanto os inóculos que foram consistentementes transferidos da indumentária branca para a pele de maneira significativa, representam um potencial risco aos pacientes, sustentam a decisão do Reino Unido em banir o uso das mesmas.
“Antes de tentar minimizar a taxa de transmissão de infecção nosocomial, existe, no Brasil, diversas normatizações do Ministério do Trabalho e Emprego que protegem o trabalhador e obrigam o uso de um EPI (jaleco branco) de mangas longas sempre que o risco for identificado. Segundo as mesmas normas, o risco é intrínseco ao serviço de saúde, ao adentrar na edificação você está exposto aos agentes biológicos. Deixar de vestir o avental durante a jornada de trabalho é como retirar o capacete dentro de uma obra, ou como retirar a N95 para tomar uma Coca-Cola enquanto examinamos um doente em isolamento para Aerossóis. Esse trabalho mostra que somos os vetores de transmissão de infecção nosocomial além de vetores da transmissão dos mecanismos de resistência antimicrobiana posto que diversos mecanismos de resistência podem ser transmitidos para diversas outras espécies por conjugação”
Letter to the Editor
Transmission of nosocomial pathogens by white coats: an in-vitro model
Several studies have documented that clothing worn in the healthcare setting can become contaminated with nosocomial pathogens, which can remain viable on fabrics for prolonged periods of time.1–8 White coats are typically not laundered daily and cannot be decontaminated between patient encounters. However, the primary opposing argument to banning white coats is that it has not been shown that organisms contaminating clothing can be transmitted to patients. The objective of this study was to determine whether multidrug-resistant organisms could be transferred from contaminated white coats to skin in an in-vitro model.
Suspensions of clinical isolates of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and pan-resistant Acinetobacter baumannii (PRA) were prepared at a 0.5 McFarland turbidity standard, and serially diluted to a concentration of 1:100 000. Swatches of a clean, 100% cotton, laboratory coat were inoculated with 0.2 mL of the bacterial suspension. Pig skin was obtained, cleansed with soap, 10% povidone-iodine, and alcohol, and allowed to dry. Touch preps of skin samples were performed to verify the effectiveness of antisepsis.
Sanitised pig-skin samples were then rubbed across the inoculated swatches. A touch prep of the pig skin on to selective media was performed to determine whether the inoculated organism could be isolated from the pig skin. The selective media used were CHROMagar_ (Becton Dickinson, Franklin Lakes, NJ, USA) for the MRSA-inoculated swatches, brain–heart infusion (BHI) with vancomycin for the VRE-inoculated swatches, and MacConkey for PRAinoculated swatches. These steps were performed in duplicate for each of the three study isolates at times 1, 5 and 30 min post inoculation.
During the time intervals the inoculated cloths remained at room temperature without any manipulation. Plates were read at 24 h and reported as growth or no growth. Purity plates were prepared of the inoculum, pig skin and cloth to ensure that at each step no other organisms could be isolated. To verify that the test isolates were viable on the swatches at the time of transfer to the pig skin, the swatches of cloth were incubated for 24 h in thioglycolate broth. The thioglycolate broth was then plated to selective media to verify again that the study isolate was retrievable from the cloth.
We demonstrated that MRSA, VRE and PRA could be transferred from cloth to pig skin 1, 5 and 30 min after inoculation at concentrations of 0.5 McFarland and at a 1:100 dilution (Table I). PRA could also be transferred at a dilution of 1:1000.
Table I Growth of organisms at serial dilutions (beginning at 0.5 McFarland)
The organisms could be isolated at even the smallest concentrations from the swatches after incubating in thioglycolate media, confirming the viability of the study isolates on the swatches.
Our data show that the potential for contaminated white coats to spread MRSA, VRE, and PRA in the healthcare setting does exist. While the inocula that consistently transferred from cloth to skin were large, it nonetheless represents a potential risk to patients and adds support to the UK ban on white coats. The primary limitation of the study is our inability to know the clinically relevant inoculum size for transmission and the environmental effects that may differ between the laboratory and the clinical setting. The major strength of this paper is that it establishes biological plausibility for the transmission of important nosocomial pathogens by contaminated clothing. While practices in medicine are rarely implemented on the basis of biological plausibility alone, we believe a strong argument can be made to do so when the intervention poses no harm, has the potential to improve care, and costs little. Further research is needed to determine the impact of ‘bare below the elbows’ in the clinical setting.
Conflict of interest statement:
D.L.B. was supported by the Infectious Diseases Society of America Medical Scholars Program 2009.
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a Division of Infectious Diseases, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
b Virginia Commonwealth University Medical Center, Richmond, VA, USA
Corresponding author. Address: VCU Medical Center,
Box 980019, Richmond, VA 23298-0019, USA.
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