#6 bacteria part 2 notes.docx

Bacteria Part 2 Pseudomanads Pseudomonas Aeruginosa most commonly isolated Gram stain – straight gram-negative rod Environmental inhabitant; domestic and hospital environments; water Opportunistic pathogen – burn wounds Major cause of bacteremia – particularly nosocomial Community-acquired Skin (j...

Bacteria Part 2 Pseudomanads Pseudomonas Aeruginosa most commonly isolated Gram stain – straight gram-negative rod Environmental inhabitant; domestic and hospital environments; water Opportunistic pathogen – burn wounds Major cause of bacteremia – particularly nosocomial Community-acquired Skin (jacuzzi), external ear canal (swimmer’s ear) respiratory tract (cystic fibrosis patients) Hospital acquired Respiratory tract, UTI, wounds, bacteremia, CNS Pseudomonas aeruginosa: Media BAP Spreading and flat Serrated edges Confluent growth Metallic sheen Grapelike or corn taco-like odor Mucoid colonies in cystic fibrosis patients Campylobacter/Helicobacter Curved GNR; stain faintly “Seagull wings” Campylobacter jejuni Gastroenteritis: most common cause world-wide Self-limiting with symptoms resolving in 3 – 6 days Grows well at 42 degrees C Characteristic darting motility Helicobacter 1983 – discovery of curved organisms in human stomach Called Campylobacter pylori Name changed in 1989 Causes gastritis, peptic ulcers, gastric cancer Strong urease producer – survives gastric acids by releasing ammonia Spirillum vs Spirochetes Spirillum Genus Spiral shaped bacteria with rigid cell wall External flagella Spirochetes Phylum Spiral shaped bacteria with flexible cell wall Internal flagella Spirochetes Leptospira, Borrelia, Treponema Gram-negative Helical body Flexible cell wall Periplasmic flagella Leptospira Thin tightly coiled with hooked ends Too small to visualize on light microscope Silver, dark field Zoonosis of worldwide distribution in many wild mammals may be transmitted to domestic animals esp farm animals Causes leptospirosis in humans manifests in many ways: CNS to kidney to liver Usually self-limiting Severe infection called Weil’s disease or may lead to kidney failure Transmission by contact with urine of infected animal Prevention by drinking only potable water and vaccination of domestic animals Treatment – penicillin affective if given during early stage (2 – 4 days) Borrelia burgdorferi Etiologic agent of Lyme disease Fever, headache, fatigue “target” lesion at bite More serious symptoms may develop later in some people Arthritis Heart problems – possibly long term CNS – nerves Transmitted via Ixodes tick Not spread human to human = non communicable Most outbreaks are June-September More people are outdoors Drug of choice-Tetracycline Treponema palladium Causative agent of syphilis Exclusively a human pathogen Acquired by Direct genital/non-genital contact with an individual who has an active primary or secondary syphilitic lesion Transplacental transmission to a fetus Virulence factor – able to cross intact mucus membrane and placenta, disseminate throughout body, and infect almost any organ 3 Stages of disease Primary stage Rapidly disseminates to lymph nodes and other organs via bloodstream Lesion, called a chancre, develops at site of inoculation in 10 – 90 days Non tender, firm, raised lesion Lesion is highly contagious Not always in visible area Secondary stage 2 – 12 weeks later Lasts several weeks may relapse Headache, sore throat, fever, lesions of mm and rash Lesions and rash highly contagious Tertiary stage Latent syphilis Not contagious 1/3 biologically cured 1/3 latent for life but still reactive 1/3 develop symptoms decades later Lesions in skin, bones, liver Degenerative changes in CNS cardiovascular lesions Aneurysms Aortic valve problems Mycoplasma No cell wall Does not stain with gram stain Adhere to epithelium of mucosal surfaces in respiratory and urogenital tracts Not eliminated by mucus secretions or passage of urine Mycoplasma pneumoniae Respiratory diseases Primary Atypical Pneumonia “Walking Pneumonia” Always considered a pathogen Spread by respiratory droplets Mycoplasma hominis Urogenital tract disease Opportunistic pathogen Rickettsia Short gram-negative rods Obligate intracellular pathogens – can only grow in cytoplasm of host cells All spread by arthropod vector Rickettsia rickettsii Causes Rocky Mountain Spotted Fever Humans acquire infection through tick bites Most severe of the rickettsial diseases Phagocytized and able to replicate inside cell cytoplasm and nucleus Spread cell to cell without damage to cells Spread by blood Flu like symptoms with rash Vasculitis including lungs brain and heart 20% mortality rate if not treated Endemic typhus rat flea – Rickettsia typhi Milder Fever, headache, 50% get rash Complications rare Epidemic louse-borne typhus – R. prowagekii Reservoir – flying squirrels in eastern US and humans Similar to RMSF 40% mortality in untreated Coxiella burnetti Is a rickettsial disease Only rickettsial disease transmitted from animals to human by inhalation Typically of dried birthing fluids no insect vector necessary but possible Also spread by ingestion of unpasteurized milk Causative agent of Q fever High fever and maybe rash Rapid dissemination affecting several types of tissue Chronic disease esp cardiovascular Often isolated from cattle, goats, & sheep Worldwide distribution Occupational disease Found among people who work with livestock or research animals Chlamydia Cannot produce ATP Cannot survive outside animal host cell Obligate intracellular pathogens Cell wall similar to gram-neg Unusual replication cycle 2 forms of organism Elementary body (EB) infectious Reticulate body (RB) noninfectious Chlamydia psittaci Causes psittacosis (ornithosis, parrot fever) Humans contract through inhalation of respiratory droplets or dust from droppings of infected birds Symptoms - lower respiratory infection, fever, non-productive cough, leads to pneumonia CNS involvement common – encephalitis, convulsions, coma Chlamydia trachomatis Human infection Eye infections – 2 distinct forms Trachoma – underdeveloped countries Chronic keratoconjunctivitis that leads to blindness in 15 – 20 years if not treated – scars the cornea Usually contracted by infants and children by contact with infected person Transmitted by contaminated hands, clothing, and eye-seeking flies Inclusion conjunctivitis Inflammation of conjunctiva in adults and infants in populations where genital infections are common Acute, copious, purulent eye discharge Genital infection – spread by close contact Single most frequent bacterial STD in U.S. (over 4 million cases per yr) Males Nongonococcal urethritis, epididymitis, prostatitis Females Urethritis, endometritis, PID Lymphogranuloma venerum (LGV) Immigrants, travelers inguinal swelling, lymphatic drainage