African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Determination of decimal reduction time (D-value) of chemical agents used in hospitals for killing airborne isolated bacteria

Ranya Aly Amer1*, Safinaz Aly Mady2, Hoda H. Yusef 2, and Soraya Sabry2
1Environmental Biotechnology Department, GEBRI, City for Scientific Research and Technology Applications (SRTACity). Egypt. 2Botany and Microbiology Department, Faculty of Science, Alexandria University. Egypt.    
Email: [email protected], [email protected]

  •  Accepted: 03 June 2013
  •  Published: 25 June 2013


Due to the growing numbers of infection outbreaks in hospitals, it is essential to set up an effective sanitation program. The kinetic parameter of killing time (D-value) was experimentally determined to study the effectiveness of some chemical agents used in hospitals. A total of 115 Air-borne bacteria were isolated from 12 wards of a hospital in Alexandria, Egypt. They were tested for their resistance to different antibiotics and commercial disinfecting agents. Three isolates were selected, identified and their D-values were determined against seven chemical agents (hydrogen peroxide, chlorine, betadine, phenik, iodine, dettol, and savlon). The bacterial strains were Staphylococcus aureusPseudomonas aeruginosa and Bacillus subtilis representing the Gram positive,Gram negative and spore former, respectively. The results revealed that P. aeruginosawas the most sensitive organism where B. subtilis and S. aureus showed approximately same resistance pattern. The data of this study reflect the importance of selecting the appropriate chemical agent to be used for killing specific microorganisms in appropriate time. In conclusion, successful disinfection depends upon the selection of the correct chemical agent associated with a proper disinfecting procedure.


Key words: Chemical agents, disinfection, D-value, hospitals, air borne bacteria.