Corybacteruim,Listeria, Legionella By: Maria Rosario L.Lacandula,MD,MPH Department of Microbiology and Parasitology College of Medicine Our Lady of Fatima University

Corynebacteruim C. diptheriae –Irregularly staining,pleomorphic, bacillus –Arranged in V or Y configuration-chinese characters –Normal colonizer of the skin, upper respiratory tract,GIT & GUT in humans –Metachromatic granules

Virulence Exotoxin- tox gene by a lysogenic bacteriophage –A-B exotoxin B-subunit- receptor-binding region and translocation region A- subunit- catalytic region –Receptor for the toxin- heparin binding epithelial growth factor

Epidemiology Worldwide distribution-asymptomatic carriers and unvaccinated hosts Humans-reservoirs, carriage in oropharnyx or on skin hosts Spread- person to person by respiratory droplets or skin contact Seen among unvaccinated people living in crowded urban areas and in children and adults with waning immunity

Diseases Clinical presentation of diptheria –Site of infection –Immune status of the patient –Virulence of the organism Asymptomatic-fully immune Mild respiratory disease-partially immune Fulminant fatal disease-non immune patients

Diseases Respiratory Diptheria –I.P- 2-6 days –Sudden onset, with malaise, sore throat, exudative pharyngitis and low grade fever –Cervical lymphadenopathy –Pseudomembrane –Complications: breathing obstruction, cardiac arrythmias, coma and death Paralysis of soft palate polyneuritis

Diseases Cutaneous Diptheria –Papule- chronic non healing ulcer, covered by a grayish membrane

Laboratory Diagnosis Microscopy – non specific Culture- should be performed on nonselective and selective media –Cysteine-tellurite agar, serum tellurite agar, loeffler’s meduim) Biochemical tests Toxigenicity testing –ELEK test/ PCR

Treatment, prevention & Control Diptheria- diptheria antitoxin Penicillin or erythromycin Vaccination- booster every 10 years –DPT Schick test

Listeria Listeria monocytogenes- only human pathogen Short, gram positive, facultatively anaerobic bacillus, singly, pairs, or in short chains Motile- tumbling motion-room temperature but not at 37 C Immunocompromised

Virulence Intracellular pathogen-macrophages, epithelial cells and cultured fibroblast Entry- nonphagocytic cell-internalins Exotoxin-listeriolysin O and two different phospholipase C enzymes Movement- Act A to cell membrane Filopod- push bacteria to adjacent cell Favor Growth- inside refrigerator

Epidemiology Isolated in soil, water, and vegetation and fro wide variety of animals, including humans Disease- consumption of contaminated food products ( soft cheese, milk, turkey, raw vegetable esp cabbage); transplacental spread from mother to offspring Sporadic cases and epidemics occur throughout the year but peak in warmer months Young and the elderly as well as patient with defects in cellular immunity are at risk

Diseases Neonatal infections- bacteremia, meningitis, meningoencephalitis –Early onset- acquired in utero- granulomatosis infantica- formation of disseminated abscesses and granuloma in multiple organs –Late onset- acquired at or soon after birth- meningitis or meningoencephalitis Adult- mild influenza-like illness, primary bacteremia, and meningitis

Laboratory Diagnosis Microscopy –CSF gram stain show no organism Culture –Grows on most conventional media- small round colonies on agar after 1 to 2 days Use selective media and cold enrichment

Treatment, Prevention and Control Penicillin or ampicillin with gentamicin High risk- avoid eating raw or partially cooked foods Avoid storage of raw vegetable inside the refrigerator for long periods of time

Legionella Gram negative bacilli outbreak of severe pneumonia Short coccobacilli in tissue and pleomorphic on artificial media Do not stain with common reagents Requires L-cysteine and enhanced growth with iron salts Dieterle’s stain

Virulence Facultative intracellular parasite- alveolar macrophages and monocytes Prevents phagosome lysosomal fusion

Epidemiology Commonly found in natural bodies of water, cooling towers, condensers and water systems Patient at high risk- patient with compromised pulmonary function and decreased cellular immunity

Diseases Pontiac fever –Self limiting illness characterized by fever, chills, myalgia, malaise, headache with no evidence of pneumonia –Symptoms develop over 12 hour period persisted for 2-5 days then resolved spontaneously Legionnaires’ disease –More severe –I.P 2-10 days –Primary manifestation- pneumonia –Involvement of GIT, CNS, liver and kidneys

Laboratory Diagnosis Microscopy –Most sensitive- Direct Flourescent antibody Culture –Medium of choice- BYCE- buffered charcoal- yeast extract agar –Grow in air or 3-5% CO2 at 35 C after 3-5 days –Colonies- ground glass appearance

Laboratory Diagnosis Antigen detection- ELISA, RIA Latex agglutination test Serology- IFA Treatment –DOC- erythromycin or tetracycline