Bacteriology Gram Negative, Acid Fast, Spirochetes + Mycoplasma Flashcards
(57 cards)
1
Q
What are the groups of gram negative bacterias?
A
1) Neisseria (pathogenic, diploid cocci)
2) The Enterics – GI tract organisms –> Escherichia, Salmonella, Shigella, Vibrio, Campylobacter, Helicobacter, Klebsiella, Pseudomonas, Proteus, Bacteroides
3) Haemophilus, Bordetella, Legionella –> Respiratory tract organisms
4) Yersenia, Francisella, Brucella, Pasteruella –> Zoonotic diseases – organisms from animals
5) Chlamydia and Rickettsia
6) Spirochetes
2
Q
Neisseria meningitidis details.
A
- Meningitis –> leading cause of death from infection in children
- Meningococcemia –> sepsis
1) Capsule
2) Pili
3) Endotoxin (LPS): blood vessel destruction and sepsis –> PETECHIAE - Spreads via respiratory secretions
- Infants aged 6 mos to 2 years of age
- Military recruits
- College freshmen
3
Q
Neisseria gonorrhoeae details
A
- Causes 2nd most common reportable bacterial disease
- Pili – adhere to host cells, and have changing antigens
- Neonatal conjunctivitis
- Pelvic inflammatory disease (PID) – infection of:
- Uterus – endometritis
- Fallopian tubes – salpingitis
- Ovaries - oophoritis
4
Q
Moraxella catarrhalis details.
A
-In the same phylogenic family as Neisseria
Causes 3 major conditions
1) Otitis media
2) Upper respiratory infection (URI) in adults with chronic obstructive pulmonary disease (COPD)
3) Pneumonia in the elderly
5
Q
Describe characteristics of the Enterics.
A
- Either part of normal intestinal flora or cause GI disease
- All transmitted by the fecal-oral route
- Produce: Diarrhea, Various other infections (UTI, pneumonia, sepsis, especially in debilitated patients)
- Associated with being acquired in the hospital
- Can develop antibiotic resistance
6
Q
Escherichia coli diarrhea details
A
- Affects infants or adults
- Infants are susceptible due to lack of immunity
- Death can occur due to dehydration
-Severity of illness depends on which virulence factors the strain possesses
7
Q
Enterotoxigenic E. coli (ETEC) details.
A
- Travelers’ diarrhea or Montezuma’s revenge
- Pili – virulence factor
- Exotoxin - after binding, it releases exotoxin
- Exotoxin is similar to that released in cholera
- Electrolyte loss and dehydration
- Extremely watery diarrhea –> looks like “rice water”
8
Q
Enterohemorrhagic E. coli (EHEC) details.
A
-Pili – virulence factor
-Exotoxin - secretes powerful toxin called Shiga-like toxin (verotoxin) –> Inhibits protein synthesis, causing intestinal epithelial cell death
-Bloody diarrhea with severe abdominal cramps (hemorrhagic colitis)
Example: strain 0157:H7 linked to HAMBURGER MEAT
9
Q
Enteroinvasive E. coli (EIEC) details.
A
- Same disease state as that produced by Shigella
- Virulence factor – a plasmid that enables the bacteria to invade through epithelial cells
- INVADES THROUGH THE INTESTINAL WALL causing immune-mediated inflammatory reaction and fever
- Bloody diarrhea with WBCs
10
Q
Escherichia coli UTI details.
A
- Travels up urethra to infect bladder (cystitis) and/or the kidney (pyelonephritis)
- Most common cause of UTI
- Most often occurs in women and in hospitalized patients with urethral catheters
- UTI symptoms: Dysuria, Urinary frequency
11
Q
Escherichia coli meningitis details.
A
- A common cause of neonatal meningitis
- Most common cause is GBS
- Most susceptible during first month of life
12
Q
Escherichia coli sepsis details.
A
- Most common cause of gram-negative sepsis
- Usually occurs in debilitated hospitalized patients
13
Q
Escherichia coli pneumonia details.
A
Common cause of hospital-acquired pneumonia
14
Q
Klebsiella pneumoniae details.
A
- Encapsulated, non-motile
- Second most common cause of sepsis in hospitals (after E. coli)
- UTI in hospitalized patients with Foley catheters
- Pneumonia in debilitated patients
- 50% have bloody sputum = Red “CURRATE JELLY SEPTUM”
- High mortality
15
Q
Proteus mirabilis details.
A
- Very motile gram negative rod
- Present in colon and soil and water
- Common cause of: UTI + Hospital acquired infection (nosocomial)
16
Q
Enterobacter details
A
- Motile
- Part of normal intestinal flora
- Can cause hospital-acquired infections
17
Q
Shigella details.
A
- Non-motile, always a pathogen
- Humans are its only host
- Transmitted by fecal-oral route via fecally-contaminated water and hand-to-hand contact
- Preschool children, nursing homes
- Similar to enteroinvasive E. coli (EIEC)- both INVADE INTESTINAL EPITHELIUM and release shiga toxin
- Damaged colon can’t reabsorb fluids, causes diarrhea
- Diarrhea with bright red blood and WBCs
18
Q
Salmonella details
A
- lives in GI tract of animals
- Always pathogenic
- Infects humans when there is contamination of food or water with animal feces
- Most commonly acquired in the US from CHICKENS and UNCOOKED EGGS
- Most common manifestation is diarrhea (gastroenteritis)
19
Q
Salmonella typhi details
A
- Causes Typhoid Fever (enteric fever)
- Invades intestinal epithelial cells + regional lymph nodes
- Can survive inside other cells – a FACULTATIVE INTRACELLULAR PARASITE
- Fever, headache, abdominal pain 1-3 weeks after exposure
- Chronic carriers of S. typhi carry it in their GALLBLADER
20
Q
Yersinia enterocolitica details
A
- Acute gastroenteritis
- Animals are a major source
- Humans ingest contaminated food or water
- Can survive and grow in the cold
21
Q
Vibrio cholera details
A
- Curved gram-negative rod with single flagellum
- Causes cholera
- Fecally-contaminated water is usual source
- Bacteria attach to cells and release cholera toxin
- Abrupt onset of “rice water” diarrhea – rice water
- Death by dehydration
22
Q
Campylobacter jejuni details
A
- One of the 3 most common causes of diarrhea in the world
- Reservoirs are wild and domestic animals and poultry
- Often via contaminated water via fecal-oral route
- Organism invades lining of small intestine
- Bloody, loose diarrhea
23
Q
Helicobacter pylori details
A
-Most common cause of duodenal ulcers, 2nd leading cause of gastric ulcers
24
Q
What bacteria group is acquired through respiratory tract?
A
- Haemophilus influenzae
- Bordetella pertussis
- Legionella pneumophilia
25
Haemophilus influenzae details
- 6 capsule types
- Type B is associated with more invasive disease: meningitis, epiglottitis, septic arthritis, otitis media, and respiratory disease in adults with preexisting lung conditions
- Haemophilus influenzae type B (Hib) --> meningitis
- Inhalation, lymph node and blood invasion, meninges
- HIB vaccine given to children at 2, 4, 6, and 15 mos
26
Bordetella pertussis details
- Causes whooping cough
- Virulence factors allow it to bind to ciliated epithelial cells of trachea and bronchi and destroys them
- Recent resurgence of whooping cough in adolescents and adults with waning immunity from their vaccine
- Booster now recommended for adults ages 19-64
- Highly contagious, spread via respiratory secretions
27
Bordetella pertussis characteristics
-Catarrhal stage – fever, runny nose, sneezing, cough
-Paroxysmal stage – fever subsides, bursts of nonproductive cough
“whoop” sound heard during inspiratory gasp
-Convalescent stage – attacks less frequent, no longer contagious
-Treatment mainly supportive, erythromycin recommended in first two stages
28
Bordetella pertussis Vaccination.
- Initial series: current vaccine covers B. pertussis along with tetanus and diphtheria --> DTaP (Diphtheria-Tetanus-acellular Pertussis)
- Given at 2, 4, 6, 15-18 mos, and 4-6 yrs
- Booster: recommended for ages 19-64 --> Tdap (Tetanus-diphtheria-acellular pertussis)
29
Legionella pneumophilia details
- Causes Legionnaires’ disease, Legionnaires’ pneumonia
- Lives in water environments
- Contaminated water is aerosolized and inhaled
- AIR-CONDITIONERS, WHIRLPOOOLS, SHOWER HEADS, PRODUCE MISTERS --> In the vegetables
- Survives and replicates intracellularly
- Common cause of community-acquired pneumonia
30
Yersenia pestis details
- Causes the Bubonic plague
- Rats harbor the disease, fleas serve as vectors to humans
- Can be contracted during camping, hunting, hiking
- Human touches a dead, infected rodent or is bitten by an infected flea and bacteria invade skin
- Spreads to blood, lymph nodes, organs
- Hemorrhage occurs under skin (black death)
31
Francisella tularensis (tularemia) details.
- In differential diagnosis of bubonic plague
- Most commonly acquired from handling infected rabbits and from bites of ticks and deerflies
- Most important diseases caused are ulceroglandular or pneumonia
- Diagnosis depends on clinical picture, skin test (like PPD) and titers of antibodies
32
Brucella details
- Causes Brucellosis
- Humans acquire through direct contact with infected animal MEAT or MILK products
- Not very common in US because cows are immunized and milk is pasteurized
- Penetrates skin, conjunctiva, lungs, or GI tract
- Lymphatic spread, intracellular growth, blood and organ invasion
33
Pasteurella multocida
- Colonizes mouths of cats
- Causes the most frequent wound infection following a cat or dog bite
- May not be appropriate to close a cat bite with sutures – closed wounds provide perfect environment
- Treatment with antibiotics is appropriate
34
What bacteria have no Gram Stain Designation? What is used instead?
Mycobacteria - Acid-fast staining
• Mycobacterium tuberculosis – causes tuberculosis
• Mycobacterium leprae – causes leprosy
• Nontuberculous mycobacteria (NTB)
35
Mycobacteria GENUS general details.
- Weakly gram-positive rods with cell walls and high lipid content
- Stain better with acid-fast stain – adheres to waxy cell wall
- This group includes the organisms that cause tuberculosis and leprosy
1) Mycobacterium tuberculosis – causes tuberculosis
2) Mycobacterium leprae – causes leprosy
3) Nontuberculosis mycobacteria (NTB)
- Over 100 species in this group
36
Describe the Acid-fast staining process.
- Sample covered with red stain and heated so dye penetrates
- Pour on acid alcohol and add methylene blue counter-stain
- Lipids of Mycobacterium do not dissolve when acid alcohol is applied, so red stain does not wash off
- Acid-fast organisms resist decolorization with acid alcohol, and hold “fast” to the red stain
- Acid-fast = RED
- Non acid-fast = BLUE
37
Mycobacterium tuberculosis
- Causes tuberculosis (TB)
- People with HIV have increased risks because they lack cell-mediated immunity necessary for fighting TB
- Obligate aerobe – needs oxygen --> LUNGS
- Grows very slowly --> 6 weeks to grow in culture
38
Describe the phases of Mycobacterium tuberculosis
PHASE 1) Inhaled bacteria cause local infiltration of cells --> Bacteria multiply and survive in macrophage --> Travel through lymph and blood and infect distant organs
PHASE 2) cell-mediated immunity: eventually macrophages begin breaking up bacteria --> Macrophages present antigens to T-helper cells --> Sensitized T-cells release signals causing a macrophage attack on the Mycobacterium bacteria --> Macrophage attack causes destruction and necrosis of lung tissue (cream cheese called CASEOUS NECROSIS) --> often calcifies, forming a granuloma --> Bacteria stay alive in the granuloma, but are walled-off --> Can start to grow actively again in future
After cell-mediated immunity is induced, any further exposure to this organism will cause a localized delayed-type hypersensitivity reaction
39
Diagnosis of Mycobacterium tuberculosis.
- Intradermal injection of antigen particles from killed M. tuberculosis will cause skin swelling and redness
- PPD = purified protein derivative reveals whether a person has been infected with M. tuberculosis at some point. It does not distinguish between active, latent, and cured infection
PPD test considered positive if induration is:
> or = to 5 mm in immunosuppressed and/or HIV positive
> or = to 10 mm in those with common risk factors for TB
> or = to 15 mm in everyone else
40
Mycobacterium leprae details.
- Causes leprosy (Hansen’s Disease)
- Acid-fast rod
- Infection occurs via respiratory secretions or skin contact
- Grows better in cooler body temperatures closer to skin surface
- Skin, superficial nerves, eyes, nose, testes
41
Nontuberculous mycobacteria (NTB) details.
- Ubiquitous in soil and water
- Healthy people rarely develop disease despite daily exposure
- Mycobacterium avium-complex (MAC): Group of related bacteria belonging to genus Mycobacterium
- Causes opportunistic infection in patients with AIDS and low CD4 count
- Most common cause of NTM lung disease
- Presents clinically with fever, night sweats, diarrhea, malaise
42
Which are the bacteria without Cell Walls?
Mycoplasma pneumoniae
| Ureaplasma urealyticum
43
Mycoplasma GENUS general details
- Tiniest free-living organisms capable of self-replication
- No cell wall; only have a simple cell membrane
- Therefore, they are neither gram-positive nor gram-negative
- Lack of rigidity allows them to contort into different shapes from round to oblong – cannot be classified as rods or cocci
- 2 pathogenic species
1) Mycoplasma pneumoniae
2) Ureaplasma urealyticum
44
Mycoplasma pneumoniae details
-Mild self limited bronchitis or pneumonia
-Most common cause of bacterial bronchitis and pneumonia in teens and young adults
-2-3 week incubation period
Presents with fever, sore throat, malaise, and persistent dry cough “Walking Pneumonia”
-CXR – streaky infiltrate, looks worse than symptoms are
45
Ureaplasma urealyticum details
- Part of normal flora in 60% of healthy women
- Found in urine
- Can cause lower UTI – urethritis
- Presents with dysuria and YELLOWISH discharge from urethra
46
Spirochetes general info
-Have gram-negative cell wall, but are too small to be seen with regular light microscope
-UNLIKE all other gram-negative bacteria, they have:
An additional outer membrane containing exposed proteins --> Protects spriochetes from immune recognition
-Axial flagella that run sideways under the outer membrane
-Special procedures needed to see them: darkfield microscopy, immunofluorescence
47
What are the 3 main genera of spirochetes?
- Treponema
- Borrelia
- Leptospira
48
Treponema pallidum details.
- Causes Syphilis
- 60% of new cases = men who have sex with men (MSM)
- Often associated with HIV co-infection
- Penetrates mucous membranes by invading through abrasions
49
3 clinical stages of Treponema pallidum
- Primary syphilis
- Secondary syphilis
- Tertiary syphilis
50
Describe the primary Syphilis stage
- Painless chancre 3-6 weeks after initial contact
- Firm, ulcerated painless lesion
- Regional nontender lymph node swelling
- Highly infectious
- Resolves over 4-6 weeks without scar – can fool individual into thinking infection has resolved
51
Describe the Secondary Syphilis stage
- Bacteremic stage
- 6 weeks after primary chancre has healed
- Widespread rash, generalized lymphadenopathy
- Associated with CONDYLOMA LATUM – painless wart-like lesions
- Rash and condyloma resolve over 6 weeks
52
Describe the Tertiary syphilis stage
- Develops over 6-40 years
| - Slow inflammatory damage to organs
53
Borrelia burgdorferi details
- Lyme disease – most commonly reported tick borne illness in the US
- Animal reservoir is white-footed mouse and white-tailed deer
- Early localized stage – 10 days after tick bite --> Erythema chronicum migrans
- Late stage – can lead to chronic neurologic damage
54
Leptospira details
- Long, thin aerobic spriochetes
- Have hook at one or both ends
- Found all over the world in urine of dogs, rats, livestock, and wild animals
- Spriochetes penetrate abraded skin or mucous membranes
55
What are the obligate intracellular bacteria?
- Chlamydia trachomatis
| - Rickettsiae
56
Chlamydia trachomatis details
- Primarily infects eyes and genitals
- Most common STI in the US
- Babies born to mothers who are infected can develop conjunctivitis or pneumonia. Babies given erythromycin eye drops
- Urethritis- usually contracted sexually
- PID shuffle, chandelier sign (cervical motion tenderness)
57
Rickettsiae details
- Requires an arthropod vector
- Rickettsia rickettsii
- Rocky Mountain Spotted Fever
- Wood or dog tick bite (tick is reservoir and vector)
- Fever, conjunctival redness, headache, PALMAR RASH
