LISTERIA MONOCYTOGENES Basmah almaarik Lab 7 LISTERIA SPP

LISTERIA MONOCYTOGENES Basmah almaarik #Lab 7

LISTERIA SPP. � Listeria monocytogenes is the only species that infect humans. � Infection �Pregnant most common in: women still birth �Fetuses �Newborns �Immunocompromised � Specimen �CSF. �Blood. received: individuals.

LISTERIA MONOCYTOGENES MORPHOLOGY � Gram Positive Bacilli Pleomorphic rods (coccobacilli = short bacilli) can form chains. � Non-capsulated

CULTURE OF LISTERIA � Aerobic and facultative anaerobe. � Grow on Nutrient Agar: very light growth & give bluish coloration reflect blue light. Nutrient Agar

CULTURE OF LISTERIA � On BA: small translucent drop-like colonies (moist) with small zone of slight beta-hemaolysis

CULTURE OF LISTERIA � Can grow at refrigeration temperature (4 ˚C) � Temperature range for growth is 3 – 45 ˚C; with an optimum of 30 ˚C. � 24 h.

HOW TO DIFFERENTIATE BETWEEN GROUP B STREPTOCOCCUS AND LISTERIA? Listeria. � Catalase +ve. � CAMP Group B Streptococcus. � Catalase –ve. +ve. � CAMP +ve (GBS)

HOW TO DIFFERENTIATE BETWEEN GROUP D STREPTOCOCCUS AND LISTERIA Listeria. � Catalase � Esculin +ve. Hydrolysis Group D Streptococcus � Catalase � Esculin (GDS) -ve. hydrolysis +ve

HOW TO DIFFERENTIATE BETWEEN CORYNEBACTERIUM AND LISTERIA? Listeria � Short gram positive rods, can occur as diplobacilli or in short chain. � Catalase � Motile +ve. at room temperature 25 ºC Corynebacterium spp. � Polymorphic gram positive rods. � Catalase � Non +ve. motile at any temperature

MOTILITY OF LISTERIA MONOCYTOGENES � Semisolid medium showing the typical "umbrella" growth. Negative control non-motile Positive umbrella like motility at Room Temperature

MOTILITY TESTING USING WET PREPARATION � Wet preparation examined under microscope X 40. Slide + drop of saline examine under X 40 Listeria monocytogenes Distinctive tumbling motility in a liquid medium @ 25 ºC

SUMMARY OF LISTERIA IDENTIFICATION USED IN THE LABORATORY 1. Gram stain (short gram positive rods) 2. Catalase +ve. 3. Slight beta-hemolysis on blood agar. 4. Umbrella like motility on semi-sold media (soft agar) at room temperature.

For Pregnant women and others at higher risk for Listeriosis: • Keep your refrigerator clean and cold—below 40° F. • Refrigerate or freeze food within two hours. • Thoroughly cook meat and poultry. ØIf you just can’t resist the idea of a pastrami and Swiss, be sure to heat the meat until steaming to kill bacteria. • Separate uncooked meats from other foods. • Eat only pasteurized dairy products. • Avoid soft cheeses like feta. • Don't eat refrigerated meat or seafood spreads, and smoked seafood

YOUR WORK FOR TODAY 1. 2. 3. Perform Gram Stain. Perform Catalase. Inoculate organism in soft agar to see Umbrella like motility. FOR DEMONSTRATION: 1. 2. 3. 4. See See Listeria on blood agar. listeria on Nutrient agar. umbrella like motility in a soft agar. gram stain of Listeria.