Open Access Oke et al., 1:7 http://dx.doi.org/10.4172/scientificreports.344 Research Article Open Access Open Access Scientific Reports Scientific Reports Open Access Volume 1 • Issue 7 • 2012 Keywords: Formalin; Ethanol; Inactivation; Mycobacterium tuberculosis Introduction Formalin is widely used to fx histological preparations, and as preservatives, in embalming solutions. It is an age-long practice in medical laboratories [1-3]. It is generally accepted that the risk of contracting tuberculosis is relatively high among Medical Laboratory workers and Pathologists. It is an assumption that once tissue is fxed in formalin, the risk for transmission and subsequent infection of Mycobacteria is greatly reduced, if not altogether eliminated [4-6]. Cadavers remain a practical teaching tool for Anatomists and Medical educators teaching gross anatomy. Infectious pathogens in cadavers that present particular risks include Mycobacterium tuberculosis, Hepatitis B and C, the AIDS virus HIV, and Prions that cause transmissible spongiform encephalopathies [7]. Recent studies have however, suggested that formalin does not efectively inactivate Mycobacterium tuberculosis in formalin-fxed tissue [4-13]. In this study we tried to test the inactivation ability of (a) 10% formalin fxation and (b) treatment of tissue with 75% ethanol, 2 hours prior to 10% formalin fxation. Multiple Drug Resistant (MDR) and Multiple Drugs Susceptible (MDS) strains of Mycobacterium tuberculosis were employed. Methods Ofcial consent was obtained from the Head of Department, Chest Clinic, Baptist Medical Centre Ogbomoso. All subjects included in this study were volunteers. Sputa were collected from subjects at the Chest clinic of Baptist Medical Centre Ogbomoso. Samples were stained by Ziehl-Neelsen’s (ZN) technique for Acid Fast Bacilli (AFB). Positive AFB samples were cultured on Lowenstein-Jensen (L-J) medium before the commencement of multiple drug therapy [14,15]. Te diferent drugs used at the clinic include; rifampicillin, isoniazid (INH), pyrazinamide and ethambutol. Primary growth on L-J was kept. Another round of sputa was collected from the same sets of subjects afer the second and ffh months of directly observed multidrug therapy (DOT). Te samples were stained. Te positive AFB smears at the second and ffh month *Corresponding author: Dr. Oke AJ, Faculty of Basic Clinical Sciences, Bowen University Teaching Hospital, Ogbomoso, Nigeria, Tel:+2348034231902; E-mail: adefolaames@yahoo.com Received September 20, 2012; Published September 27, 2012 Citation: Oke AJ, Adeyemo AD, Oke AA (2012) Multidrug-Resistant Human My- cobacterium tuberculosis Strain Resisted Inactivation by 10% Formalin. 1:344. doi:10.4172/scientifcreports.344 Copyright: © 2012 Oke AJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Multidrug-resistant strain of Mycobacterium tuberculosis (MDR-Tb) and Multidrug-sensitive (MDS-Tb) isolated from humans were injected subcutaneously into the guinea pig. One set of infected lungs of animals was fxed in 10% formalin pH 7.2, while the other set was treated with 75% ethanol, 2 hours prior to fxation in 10% formalin. After six months of fxation, MDS-Tb strains were completely inactivated by both methods of fxation. MDR-Tb strains resisted inactivation by 10% formalin, but were inactivated by the treatment with 75% ethanol 2 hours prior to 10% formalin fxation. Multidrug-Resistant Human Mycobacterium tuberculosis Strain Resisted Inactivation by 10% Formalin Oke AJ 1 *, Adeyemo AD 2 and Oke AA 3 1 Department of Medical Microbiology, Bowen University Teaching Hospital, Ogbomoso, Nigeria 2 Department of Medical Microbiology, College of Medicine, University College Hospital, Ibadan, Nigeria 3 Department of Medical Microbiology, College of Health Sciences, Igbinedon University, Okada, Nigeria of DOT were considered to be MDR-Tb [16,17]. Te negative AFB smears at the second and ffh months of DOT were considered MDS- Tb, and the primary growth from such samples were used as MDS-Tb. MDR-Tb sputa samples were cultured on L-J, and incubated. One set of animals was injected subcutaneously with the primary MDS- Tb growth, while another set was injected with the MDR-Tb growth [14]. Control animals were injected with sterile normal physiological saline. Animals were kept, fed on pellets and sterile water. Tey were watched for symptoms of disease, afer which they were scarifed and lungs excised. Parts of the lungs were processed for culture on L-J media to confrm infection in the animals. Parts of infected lung tissue were fxed in 75% ethanol for 2 hours and then in 10% formalin. Other parts of the lungs were fxed in 10% formalin pH 7.2. Te fxed tissues were kept for 6 months. Lung tissues were processed for culture on L-J media, and incubated aerobically at 36ºC. Results Fify AFB-positive subjects were encountered in this study. Four (8%) were carrying MDR-Tb. Te animals injected with mycobacteria cultures developed local swellings and weight-loss afer one month, and mycobacteria were isolated from their lungs when cultured on L-J medium. Tere was no growth from the lung tissue of the control animals. Tere was no growth from the lungs of MDS-Tb infected animals in both fxation methods (Figures 1 and 2). In the MDR-Tb infected lungs, there was no growth in the 75% ethanol, 10% formalin fxation, but there was growth in the 10% formalin fxation (Figures 3 and 4).