LAGOS STATE UNIVERSITY, OJO 5th Conference of The Faculty of Science 10th – 14th October, 2017.

TITLE OF PAPER PRESENTATION SODIUM BISELENITE INHIBITED SALMONELLA GROWTH ON DEOXYCHOLATE CITRATE AGAR Presenter: AMISU, Kehinde Olugbenga Date: 12TH October, 2017.

Outline Of Presentation: Introduction Morphologic and biochemical characteristics of Salmonella Epidemiology of Salmonella infection Laboratory diagnosis Selectivity of DCA and Sodium biselenite Research problems Aim of the Study Materials and Methods Results Discussion and Conclusion List Of References

MORPHOLOGICAL AND BIOCHEMICAL CHARACTERIISTCS OF SALMONELLA Gram negative, rod shaped, peritrichous and motile bacterium Non-fastidious, facultative anaerobe, non-lactose fermenter Reduces sulfur to H2S Source: Kemal (2014)

EPIDEMIOLOGY OF SALMONELLA An enteropathogenic bacterium of humans and animals Found and shed in faeces of infected humans and animals Transmitted through contaminated foods and water sources causes gastroenteritis and enteric fever A major health problem, especially in developing countries Source: Freitas et al., 2010; Kemal, 2014

LABORATORY DIAGNOSIS An enteropathogenic bacterium of humans and animals Found and shed in faeces of infected humans and animals Transmitted through contaminated foods and water sources causes gastroenteritis and enteric fever A major health problem, especially in developing countries Source: Freitas et al., 2010; Kemal, 2014

SELECTIVITY AND SENSITIVITY OF DCA AND SODIUM BISELENITE SB highly inhibitory to coliforms SB (4g/l) is used for selective enrichment of Salmonella in foods, faeces and sewage DCA, a differentia and selective medium DCA is inhibitory to intestinal Gram positive bacteria DCA, supports the growth of enteric Gram negative bacteria Salmonella grows and produces colonies with distinct black center DCA is used for both direct and indirect detection of Salmonella SOURCE: Leifson, 1935, Baker et al., 2010

RESEARCH PROBLEMS Abundance of competitive faecal bacteria flora is a serious challenge to direct plating technique Salmonella yields from direct plating is generally low in comparison to indirect methods Indirect plating is both time consuming and costly inhibition of more competitive faecal flora on direct plating with increased inocula size and should improve recovery rates of Salmonella

AIM OF THE STUDY To determine the growth selective performance of DCA supplemented with SB for detection of Salmonella

MATERIALS AND METHODS Concentrated SB solution prepared and added to molten DCA forming DCASB About 1g from each of 10 poultry droppings were suspended in 9.8ml normal saline 0.2 ml of actively growing Salmonella strains (1.5x107 cfu/ml), SAL 1 to 5 added to faecal suspensions 0.1ml of faecal inoculated onto DCASB and control DCA by spread plating technique Plates were incubated at 37oC for 18-24hr Culture plates were compared for bacterial growth and recovery rates of Salmonella

RESULTS Addition of SB to molten DCA changed colour of medium (DCASB) to reddish brown No faecal bacterial growth was observed on DCASB, even with extended incubation Control plates yielded good and confluent bacterial growths Bacterial yield on control plates include coliforms, Salmonella, Proteus and Pseudomonas

DISCUSSION Laboratory diagnostic protocols play an important role in the management of infectious diseases Attempt to modify DCA with addition of SB for improved recovery of Salmonella did not support any bacterial growth, including salmonella Gross inhibition of feacal bacterial growth on DCASB suggests presence of highly toxic product formed from the interaction of SB with DCA components

DISCUSSION (CONTINUES) Suspicions for formation of potent antibacterial product(s) is further supported by the spontaneous colour change of DCASB It may be interesting to identify the unknown broad spectrum antibacterial agent The unknown active agent may be useful for microbial control, if consider safe for use

CONCLUSION The addition of SB to DCA is highly inhibitory to faecal bacteria, including Salmonella and SB-DCA combination should not be used except where gross inhibition of bacterial growths is desired.

LIST OF REFERENCES Baker, S., Favorov, M., and Dougan, G. (2010). Searching for the elusive typhoid diagnostic. BMC Infectious Diseases, 10:45. Freitas, C. G. d., Santana, A. P., Silva, P. H. C. d., Goncalves, V. S. P., Barros, M. F., Torres, F. A. G., Murata, L. S. and Perecmanis, S. (2010). PCR multiplex for detection of Salmonella enteritidis, typhi and typhimurium and occurrence in poultry meat. International Journal of Food Microbiology. 39: 15-22.

LIST OF REFERENCES (Cont) Leifson, E. (1935). Formulation and composition of deoxycholate citrate medium. Journal of Pathological Bacteriology, 40: 581 Leifson, E. (1936). New selenite enrichment media for the isolation of typhoid and paratyphoid (Salmonella) bacilli. A. J. Hyg. 24: 423-432. Kemal J (2014) A Review on the Public Health Importance of Bovine Salmonellosis. J Veterinar Sci Technol, 5:175

LIST OF REFERENCES (Cont.) North, W.R. (1950). A modified selenite enrichment broth for the detection of Salmonella. Bacteriological Proceedings, 50th General Meeting, pg. 67. Willey, J., Sherwood, L. and Wolverton, C. (2013). Prescott s Microbiology. 9th Edition, McGraw- Hill, New York. ISBN-13:9781121913967

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