Survey of Microbes Part I: Important prokaryotes Gram negative organisms, archaea, and others

Survey of MicrobesPart I: Important prokaryotes

Gram negative organisms, archaea, and others

IMPORTANT GRAM NEGATIVE

PROTEOBACTERIA

G- cocci Neisseria: ________________ N. gonorrhoeae – _____________ =

________________ Has fimbriae/pili to attach to genital

epithelium and invade Causes infiltration of pus/inflammation Fastidious – diagnose on chocolate agar

N. meningitidis Meningococcal meningitis – vaccine

available and highly recommended for college students (spread by close/direct contact)

Penicillin sensitive?

Disease/Treatments

Adults: genital, urinary, anal infections posisble

neonatal eye infection (can prevent with erythromycin eye drops)

Men can be asymptomatic some show “gleet” (copious purulent

discharge) – see link to images on supplement site.

Women: pelvic inflammatory disease

Treatment: many antibiotics (e.g. doxycycline, cipro, z-pack)

Many are now resistant! (e.g. –cillins; tetracycline)

PID most cases are

associated with _____________and genital ______________ infections

Long term infection organisms migrate into uterus, fallopian tubes

Major cause of infertility and chronic pelvic pain

See web link: http://www.niaid.nih.gov/factsheets/stdpid.htm

Sexually active teenagers are more likely to develop PID than are older women.

The more sexual partners a woman has, the greater her risk of developing PID.

Figure 23. Gonorrhea — Positivity among 15- to 24-year-old women tested in family planning clinics by state: United States and outlying areas, 2007

Gram negative rods

Enterobacteriaceae – shared characteristics

____________________; Small rods (4-5 microns long)

Peritrichous flagella (exception: Klebsiella and Shigella are non motile)

All ferment glucose (produce acid) – used for ID on differential agar

Have various surface antigens to: avoid phagocytosis, aid in adherence, SEPTIC SHOCK (associated with LPS)

Gram - rods

_______________ (LPS) – just one antigen on the outer membrane of Gram-negative bacteria.

LPS - lipopolysaccharide

Toxicity is associated with the lipid component (Lipid A) and immunogenicity is associated with the polysaccharide components.

O antigens also are components of LPS. LPS elicits a variety of inflammatory responses in

an animal, including fever. MOST LPS IS RELEASED ________________

________________________________

Gram - rods

Pathogenesis

Because of their cell envelope structure: tolerant to bile salts and toxins in GI tract Resistant to many antimicrobials produced by

the host Possibly resistant to phagocytosis

Also – LPS may be involved (along with pili, fimbrae) in binding host tissue

Gram - rods

G- bacilli – Enterobacteriaceae

_________(strain O157:H7) – enterohaemorrhagic; common food poisoning; beef – outbreaks in hamburger meat

___________________ (typhoid fever) – ______________________ - common food poisoning

(salmonellosis) ; poultry Shigella flexneri, S. dysenteriae – bloody diarrhea;

dysentery; invades mucosa shed lining of intestines up to 50% of all diarrhea deaths can be attributed to bacillary

dysentery!! 1 M cases/yr (4% death rate)

Gram - rods

READ NEWS ARTICLE on Salmonella in peanut butter

Some toxins produced by enteric bacteria

______________(from ET E. coli, Vibrio) – lead to secretion of lots of water by intestinal cells

________________ (Shigella and E. coli O157H7) – destroys host ribosomes causes cell death! What is the result?

______________ (come E. coli strains) – destroy RBCs

Invasins (Salmonella, Shigella) – invade cells (can grow intracellularly)

Gram - rods

A quick note on diarrhea…

Traveller’s diarrhea: due to contaminated water and foods; in developing countries, risk is 30-50% for travelers (1-2 wk stay)

Food poisoning: can be due to food itself (bacteria or virus living in that animal or its waste), poor food preparation (mixing cooked with uncooked) or due to unsanitary practices of food handler (fecal-oral transmission).

Other important Enterobacteriaceae

Yersinia pestis (bubonic plague) – Buboes – large, swolen lymph nodes killed more people than any other ID (killed ¼

Europe! – 25 M – in the 14th C) transmitted by ___________during blood meal MANY virulence factors

Klebsiella pneumoniae – pneumonia; has ___________, evades phagocytosis

G- bacilli

G- bacilli (some others) ___________________________(whooping cough) –

DPT vaccine – toxin kills ciliated cells Pseudomonas aeruginosa (opportunistic

infections – grows everywhere) – slime layers, fimbrae

Haemophilus influenzae – MANY diseases! Meningitis, ear infection, sinusitis, pneumonia, septicemia, arthritis, epiglottitis (life threatening) – some strains have capsule; vaccine available

Bacteroides – major constituent of gut flora; usually commensalistic but can grow elsewhere and cause problems (resistant to Abt)

G- curved ________________, the cause of Asiatic cholera.

Watery, profuse diarrhea dehydration shock renal failure death

Spread by contamination (fecal/oral esp. travel to endemic countries) and by seafood (other Vibrio spp.)

uses glycocalyx to anchor to epithelium Produces cholera-toxin (enterotoxin)

READ NEWS ARTICLE on cholera outbreak in Zimbabwe

G- Spiral shaped

Have a rigid cell wall and polar flagellaCampylobacter jejuni -- bacterial

diarrhea, especially in children. undercooked poultry or shellfish, or untreated

drinking water. _________________________– peptic ulcers;

colonizes gastric mucosal cells of humans Mode of transmission uncertain Dx – gastric biopsy and urease test >80% ulcers are Hp!

Rickettsias

Very tiny! Most are pathogens (vector borne = spread by

arthropods) ________________ ________________ parasites Rickettsia rickettsii – Rocky Mtn. Spotted

Fever – ticks Rickettsia typhi – endemic typhus (lice) Coxiella burnetti – Q fever

(http://www.cdc.gov/ncidod/dvrd/qfever/)

Spots due to small hemorrhages

Other phyla of prokaryotes

Chlammydias, Spirochetes, Photosynthetic bacteria, Archaea

(extremophiles)

Spirochetes

phylogenetically distinct group very thin, flexible, spiral-shaped

move by means of axial filaments (periplasmic flagella).

Most spirochetes are free living or harmless; a few are pathogens of animals

_____________________– Lyme disease – humans + dogs

_____________________– syphillis – hook to embed in host cell

Borrelia burgdorferi

Treponema pallidum

Cross section

Syphillis Sores occur mainly on the external genitals, vagina,

anus, or in the rectum. (also on lips and in mouth) Transmitted by direct contact (Also congenitally) first stage - small sore disappears in 2 to 8 weeks. second and third stages -- progressively worse

eventually lead to brain, heart, and blood vessel damage if not diagnosed and treated.

syphilis is 100% curable with penicillin, yet there is now more syphilis than since the late 1940s, and it is spreading rapidly.

Rising rapidly in white, homosexual male demographic

Spirochetes – Treponema pallidum

Chlammydias

Obligate intracellular parasites (cannot survive without host cell)

VERY, very tiny (thought to be viruses!)Chlammydia trachomatis – trachoma

(severe eye infection) and STD Most frequently reported ID in the US – Georgia

in top 5! (15 – 24 year old women)

C. pneumoniae – pneumonia

Photosynthetic bacteria

Green and Purple photosynthetic bacteria – do not produce O2; have bacteriochlorophyll; anaerobic; use H2S or S in their metbolism

Cyanobacteria. Chlorophyll a and other pigments; thylakoids to increase surface area; blue-green pigment is phycocyanin

great ecological importance in the global carbon, oxygen and nitrogen cycles

Oscillatoria Nostoc Anabaena with heterocyst, a specialized cell for nitrogen fixation.The large bright cell in the filament is a type of spore called an akinete

Synechococcus –marine; 25% of primary production

CyanobacteriaPhotosyntheticbacteria

Photosynthetic bacteria

CYANOBACTERIA PURPLE SULFUR BACTERIA

filamentous

Colonial (with gelatinous sheath)

Archaea – the “other” prokaryotes

constitute third Domain Archaeamore closely related to Eukarya than to

bacteriaunique genetic sequences - rRNAunique membrane lipids & cell wall

• Halophiles thrive in high salt environments

• Use red pigments for ATP (energy) synthesis

• “Red Sea”

________________ : Based on their

physiology, the Archaea can be organized into three types: ________________ --

prokaryotes that produce methane; obligate anaerobes

extreme ____________-- live at very high concentrations of salt (NaCl)

extreme (hyper) ________________ -- live at very high temperatures