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Micro Lecture Unit 3 > Gram Negative Bacteria > Flashcards

Gram Negative Bacteria Flashcards

1
Q

What characteristics do Enterobacteriaceae have?

A

Gram Positive rods
Most are motile (peritrichous flagella)
Encapsulated
Virulence factors include LPS, O, H, and K antigens
Many have “serum resistance” (Ab’s can’t attack)

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2
Q

What diseases are Enterobacteriaceae associated with?

A

Enteric (GI) infections
Bacteremia
UTI’s

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3
Q

Who is at high risk for acute diarrhea?

A 
Travelers
Consumers of certain foods
Immunocompromised
Daycare participants
Institutionalized persons (nosocomial infections)
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4
Q

What foods put a person at risk for getting acute diarrhea?

A
  • Chicken, mayonnaise, creams, eggs (Salmonella, Campylobacter, Shigella)
  • Hamburger undercooked (EHEC – enterohemorrhagic E. coli
  • Fried rice (B. cereus)
  • Seafood (Salmonella, Vibrio, Hepatitis A)
  • Fermented tofu (C. botulinum)
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5
Q

What Gram negative bacteria most commonly cause acute diarrhea?

A 
ETEC – enterotoxigenic E. coli
Shigella
Salmonella
Campylobacter
Giardia
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6
Q

What are the treatments for GI diseases such as acute diarrhea?

A

-Fluid/electrolyte replacement
Dehydration is the most common cause of death from diarrhea
-Antibiotics are not used after onset of symptoms unless systemic/severe
-Antibiotic prophylaxis when traveling to high-risk countries

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7
Q

Enteric infection symptoms: Non-inflammatory

A
  • Nausea
  • Vomiting
  • Diarrhea
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8
Q

Enteric infection symptoms: Inflammatory

A

Dysentery (severe diarrhea containing mucus and/or blood)

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9
Q

Enteric infection symptoms: Invasive

A

Typhoid Fever (enteric fever)

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10
Q

What is the mode of transmission (MOT) of most enteric bacteria?

A

fecal-oral contamination

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11
Q

What are 3 factors the host might have that increase risk of infection by enteric bacteria?

A

Low gastric acidity
low numbers of normal enteric microflora
immunocompromised

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12
Q

Pathogenicity of enteric bacteria:

A

usually ingested as preformed toxins

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13
Q

Microbial Toxins

A

Staphylococcal toxins (Staph. aureus)

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14
Q

Example of neurotoxin

A

Botulinum toxin (Clostridium. botulinum)

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15
Q

Enteric Toxins

A

having a direct effect on intestinal mucosa (elicit fluid secretions)

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16
Q

What is/are an example of Enterotoxins?

A 
Cholera toxin (Vibrio. cholerae)
E. coli toxins
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17
Q

What are attributes of Cytotoxins?

A 
mucosal destruction (often see dysentery)
Shigella dysenteriae
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18
Q

What is/are examples of Cytotoxins?

A

Clostridium perfringens
S. aureus
Clostridium difficile

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19
Q

What are attributes of Enterobacteriaceae?

A

Ubiquious (they are everywhere) - soil, water, vegetation, normal intestinal flora
Gram negative, facultative anaerobic rods
oxidase negative - no cytochrome oxidase

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20
Q

Enterobacteriaceae are members of family commonly associated with human disease:

A 
Escherichia
Salmonella
Shigella 
Yersinia 
Klebsiella 
Serratia 
Proteus
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21
Q

Enterobacteriaceae pathogens are associated with what opportunistic infections?

A

septicemia
pneumonia
meningitis
urinary tract infections (UTI)

can be primary pathogens (unrelated to immune status)

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22
Q

Are E. coli and the serotypes Lactose positive or Lactose negative?

A

Lactose positive

note: many intestinal pathogens are lactose negative
ex. Salmonella, Shigella, Yersinia

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23
Q

How are E. coli and the serotypes grouped?

A

grouped based on surface antigens (serotypes):
O antigen (lipopolysaccharide)
H antigen (flagellar)
K antigen (capsular)
O157:H7 (EHEC – enterohemorrhagic E. coli)
O148:H28 (ETEC – enterotoxigenic E. coli)

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24
Q

Describe E. coli serotype differentiation.

A

immunologic assay
growth on MacConkey agar with sorbitol (called S-Mac media)
most E. coli can ferment sorbitol (form pink colonies)
E. coli O157:H7 does not ferment sorbitol (colonies are clear/colorless)

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25
Q

Describe E. coli pathology

A
  • most strains of the pathogenic E. coli are capable of pathology only within the intestinal tract (some exceptions)
  • most pathogenic strains associated with disease in developing countries (except EHEC is common in the USA)
  • dependent upon strain, different disease severity/symptoms (e.g. pathotype)
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26
Q

Pathogenic strains produce virulence factors found on:

A

Plasmids (a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA)
Bacteriophages (viruses that infect bacteria)

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27
Q

Virulence factors include:

A 
Fimbriae (allow bacteria to stack up on each other to shelter themselves from immune system
secretion systems (the process of toxin release) and toxins
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28
Q

Pathogenic strains of E. coli include:

A 
EPEC (enteropathic)
ETEC (enterotoxic)
EHEC (enterohemorrhagic)
EIEC (enteroinvasive)
EAEC (enteroaggregative)
UPEC (uropathogenic)
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29
Q

What happens when there is destruction of the surface microvilli (small intestines)?

A 
fever
diarrhea (infantile)
malabsorption of fluids
vomiting/nausea hard to replace fluids 
non-bloody stools
common in developing countries (rare in U.S.)
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30
Q

Since EPEC pathology - diarrhea is primarily a disease of the young (less the 6 months old), what must be replaced?

A

fluid replacement is important

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31
Q

What are symptoms of EPEC pathology- diarrhea?

A

~intense vomiting - i.v. fluids are usually required
~disease self-limiting (antibiotics usually not required)
breast feeding seems to have a strong protective effect
IgA and other factors decrease bacterial attachment

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32
Q

Enterotoxigenic E. coli (ETEC) is also known as?

A

“Traveler’s diarrhea”

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33
Q

What are the types of ETEC toxins?

A

heat labile toxins (LT)
similar to cholera toxin (although not as severe)
lack of absorption of fluids = watery diarrhea
heat stabile toxins (ST)
no inflammation, self-limiting

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34
Q

ETEC strains are:

A
  • disease is self-limiting, watery diarrhea common symptom
  • exposure provides immunity
  • adults living in endemic areas, often immune children, through exposure to the many strains, eventually develop immunity
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35
Q

Therapy for ETEC includes:

A

~fluid replacement
~bismuth subsalicylate tablets (Pepto-Bismol, etc.)
~provide antibiotics to travelers in the event they get sick while abroad

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36
Q

Enterohemorrhagic E. coli (EHEC) is usually classified as:

A

usually O157:H7

strain must have virulence/toxin genes.

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37
Q

What are VTECs?

A

Vero toxin (VTEC) = “shiga-like” toxin (cytotoxin) aka Shiga toxin-producing E. coli (STEC)

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38
Q

What does an AB toxin cause?

A

“A” inactivates 28S rRNA = stop protein synthesis. Death of epithelial cells.

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39
Q

Characteristics of Streptococcus:

A

•Gram-positive cocci, arranged in pairs or chains, that are facultative anaerobes
•Often categorized based on the Lancefield classification
-Divides the streptococci into serotype groups based on the bacteria’s antigens
-Lancefield groups A and B include the significant streptococcal pathogens of humans

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40
Q

Strep classification:

A

Group A (GAS) Strep pyogenes
Group B Strep agalactiae
Group D Enterococcus faecalis
Viridans Strep mutans

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41
Q

Hemolysis - beta

Bacitracin - sensitive

A

S. pyogenes

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42
Q

Hemolysis – beta

Bacitracin - resistant

A

S. agalactiae

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43
Q

Homlysis – Alpha

Bacitracin - resistant

A

S. pnumoniae

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44
Q

Hemolysis – Alpha or gamma

Bacitracin - resistant

A

E. faecalis

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45
Q

Characteristics of Streptococcus Pyogenes:

A
  • S. pyogenes forms white colonies surrounded by zone of beta-hemolysis on blood agar plates
  • Only GAS species
  • Pathogenic strains often form a capsule
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46
Q

Group A streptococci generally only cause disease in the following situations:

A
  • Normal microbiota are depleted
  • Large inoculum enable the streptococci to establish themselves before antibodies are formed against them
  • Specific immunity is impaired
  • Direct contact with mucous
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47
Q

Group A streptococci Pathogenicity:

A

•Structural components
–Protein M, which interferes with opsonization and lysis of the bacteria and a hyaluronic acid capsule, which acts to camouflage the bacteria
•Enzymes
–Streptokinases, deoxynucleases, and C5a peptidase all facilitate the spread of streptococci through tissues
•Pyrogenic toxins that stimulate macrophages and helper T cells to release cytokines
•Streptolysins lyse red blood cells, white blood cells, and platelets

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48
Q

Group A Streptococcal Dieseases:

A
  • Pharyngitis (“strep throat”)-inflammation of the pharynx
  • Scarlet fever-rash that begins on the chest and spreads across the body
  • Pyoderma-confined, pus-producing lesion that usually occurs on the face, arms, or legs (Impetigo)
  • Streptococcal toxic shock syndrome-bacteremia and severe multisystem infections
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49
Q

What is the major species of Salmonella?

A

S. choleraesuis

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50
Q

Which organisms cause enteric fever?

A

S. choleraesuis ssp. Choleraesuis, serovar typhi (often just called S. typhi, or a better designation is Salmonella Typhi)

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51
Q

How is S. enterica ssp. enterica serotype typhimurium shorted?

A

It is shortened to S. typhimurium (Salomonella Typhimurium)

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52
Q

With Salmonella subtyping, how are serotypes determined?

A
  1. O antigen (LPS outer sugars)
  2. Surface Vi antigen (only in sub-types)
    - -Capsule antigens (vi=virulence antigens)
  3. H antigens (flagella)
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53
Q

How do most clinical labs divide Salmonella into serogroups?

A

Serogroups (A, B, C1, C2, D, and E) based on O-antigen antisera

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54
Q

What causes Salmonella diseases?

A

Ingestion of bacteria from contaminated food/water and affects the human intestinal tract.

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55
Q

What happens when bacteria from Salmonella diseases get to the in the intestinal tract?

A

Organisms get to the small intestines, where the macrophages often ingest bacteria, however the bacteria are protected from host responses (e.g. complement, antibodies, etc)

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56
Q

How does Salmonella alter host cells?

A

changes host cell to allow for “bacteria-mediated endocytosis (absorbing a substance from outside the cell)”
prevents lysosomal enzymes of macrophage from degrading bacteria

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57
Q

With Salmonella pathology, the bacteria is disseminated by macrophages to which areas?

A

The liver, spleen, lymph nodes and bone marrow.

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58
Q

What causes systemic symptoms?

A

These are due to host responses against pathogens

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59
Q

What are inflammatory cytokines?

A

Inflammatory cytokines are secreted by activated macrophages. (Cytokines are chemicals that call other WBCs to come to the area)

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60
Q

How rare is typhoid Salmonella infections?

A

It is very rare in the U.S., however 21 millions infections worldwide (~200,000 deaths)

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61
Q

Compared to typhoid Salmonella, how common is non-typhoid Salmonella?

A

Non-typhoid is much more common. Humans acquire infections from poultry/eggs, dairy, and contaminated work surfaces (cutting boards). In the U.S. ~40,000 reported cases (estimated 2 million)

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62
Q

What is Enteric (typhoid) fever?

A

It is a systemic disease caused by S. Typhi or S. Paratyphi. It is endemic (only occurs in developing countries. ~70% of U.S. cases are acquired from international travel)

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63
Q

How are Typhoid Fever and Enteric Fever similar and different?

A

Similar: Fever, nausea, rash and other systemic symptoms. Was originally called typhoid fever because of the similar symptoms to typhus.
Differ: Different bacteria, different mechanism of spreading

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64
Q

How is Enteric fever acquired and who are its host?

A

The disease is from ingesting contaminated food, and the only known host is humans.

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65
Q

Is the infectious dose low or high?

A

Dose is low. (~103 versus 106-108 for infections with other species of Salmonella)

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66
Q

What are the clinical manifestations?

A
  • febrile illness
  • disease more severe by S. typhi as compared to S. paratyphi
  • after 10-14 days of initial infection, patients have gradually increasing fever, headache, myalgia (muscle pain), malaise (fatigue).
  • at around 21 days after infection, GI symptoms present (not seen in all patients) – diarrhea
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67
Q

What is one reason why it is difficult to diagnose Typhoid Fever?

A

The variable numbers of bacteria throughout the infection

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68
Q

What are 3 potential cultures (specimens) that can be used to test a positive diagnosis for Typhoid Fever?

A

1) Stool
2) Urine
3) Bone marrow

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69
Q

What does MDR mean?

A

Multi-drug resistant

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70
Q

Are some strains of S. Typhi MDR?

A

Yes

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71
Q

What causes gastroenteritis?

A

Salmonella

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72
Q

What are 4 symptoms of acute gastritis?

A

Vomiting, abdominal pain, fever, and diarrhea

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73
Q

What causes shigella?

A

Acute infectious inflammatory colitis

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74
Q

Is mortality from shigella more common in children or adults?

A

Children

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75
Q

Is shigella a pathogen of animals or humans?

A

Humans

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76
Q

Is it easy to spread shigella to others?

A

Yes, it is highly communicable

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77
Q

What are the clinical manifestations of Shigella?

A

abdominal cramps, diarrhea, fever, bloody stools and large numbers of WBC in stool

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78
Q

What do Shigella virulence proteins cause?

A

Ruffling of epithelial cells, allows for endocytosis of the bacteria, actin rearrangement allows for cell-to-cell spread.

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79
Q

S. dysenteriae produces what toxin?

A

S. dysenteriae produces shiga toxin (similar to EHEC)

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80
Q

What are the enteric pathogens of Yersinia?

A

Y. enterocolitica, Y. pseudotuberculosis

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81
Q

Y. pestis is also known as what?

A

The bubonic and pneumonic plague

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82
Q

The zoonotic disease Yersinia is primarily found in what animals?

A

Fleas, rodents, swine, cattle, etc

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83
Q

The formation of bubos is found in what disease?

A

Y. pestis

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84
Q

What is the mortality rate of untreated patients suffering from the pneumonic plague?

A

High mortality rate - 90%

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85
Q

Is Y. entrocolitica or Yersinia sp. more common?

A

Y. entrocolitica

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86
Q

Does Y. entrocolitica cause severe or acute enterocolitis?

A

acute enterocolitis and mysenteric lymphadenitis (can mimic appendicitis)

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87
Q

How many different serotypes of Y. enterocolitica are there?

A

Over 60 (serotypes 3,8, &9 account for most human infections

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88
Q

Y. entrocolitica is associated with what risk factors?

A

Ingestion of contaminated food/ milk (can grow at lower temperatures 4C), blood transfusion septicemia

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89
Q

Yersinia can be diagnosed from what type of samples?

A

Blood or stool

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90
Q

What is cold enrichment?

A

Growth culture at 4-7C for 28 days w/ weekly subculture on SS agar

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91
Q

What are the therapies for Yersinia?

A

Plague- antibiotics and rodent control Enteric- often self limiting

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92
Q

What are two major pathogenic species of Neisseria?

A

N. gonorrheae- associated with STDS

N. meningitidis- associated with respiratory and CNS infections

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93
Q

In vitro growth is found in:

A

Obligate aerobes
Sensitive to drying ( delicate) and some products in blood(that is why one uses Chocolate agar for culture
fastidious-picky
Out-competed by normal flora so grow in presence of select antibiotics(Thayer-Martin agar)
Need 5% CO2

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94
Q

What does LPS stand for?

A

Lipopolysaccharide

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95
Q

What does LOS stand for?

A

Lipoligosaccharide

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96
Q

In Endotoxins, what is the LPS like?

A

Lipid A, core sugars, outer sugars

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97
Q

In Endotoxins, what is the LOS like?

A

Lipid A, core sugars, present in Neisseria

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98
Q

In Neisseria gonorrhoeae, what are the incidences of the disease?

A

incidence remains high in some groups defined by geography, age, race/ethnicity, or sexual risk behavior.Increasing proportion of gonococcal infections caused by resistant organisms

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99
Q

How is it transmitted?

A

Efficiently transmitted by:
Male to female via semen
Female to male urethra
Rectal intercourse
Fellatio(jpharyngeal infection)
Perinatal transmission( mother to infant)
Gonorrhea associated with increased transmission of and susceptibility to HIV infection

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100
Q

What are the virulence factors of Gonococcus?

A

Pilus
Phase variation and Antigenic variation(of pilus and opacity protein)
phase variation-differences in colony appearance
antigenic variation-varying pili antigenic type
development of a vaccine will be difficult
Endotoxin (LOS)
IgA protease-cleaves at hinge region
Serum resistance

101
Q

What are the characteristics of the genital infection Urethritis, found in men?

A

inflammation of urethra,
typically purulent or mucopurulent urethral discharge
asymptomatic in 10% of cases

102
Q

What are the characteristics of the genital infection Epididymitis, found in men?

A

inflammation of the epididymis
unilateral testicular pain and swelling
infrequent

103
Q

Most genital infection in women are?

A

Asymptomatic

104
Q

What is Cervicitis?

A

Inflammation of the cervix

105
Q

What is Urethritis?

A

Inflammation of the urethra

106
Q

What are complications in women due to gonorrhea?

A
  • Pelvic Inflammatory Disease (PID)

- Fitz-Hugh-Curtis Syndrome

107
Q

What are the gonorrhea syndromes in men and women?

A
  • Conjunctivitis

- Disseminated gonococcal infection (DGI)

108
Q

Gonorrhea infection in perinatal children causes?

A

-Infections of the conjunctiva, pharynx, respiratory tract

109
Q

What are diagnostic methods for gonorrhea?

A

Culture tests

110
Q

Laws and regulations in all states require that persons diagnosed with ????? are reported to public health authorities by clinicians, labs, or both.

A

Gonorrhea

111
Q

What are the diseases caused by N. meningitides?

A
  • Meningococcal meningitis

- Meningococcemia, sepsis

112
Q

What are the virulence factors of Meningococcus?

A
  • Polysaccharide capsule
  • Endotoxin (LOS)
  • IgA protease
  • Serum resistance
113
Q

To control Meningococcus how does the vaccine work?

A

Does NOT display same types of phase/antigenic variation as seen in NG

114
Q

To control Meningococcus how do microbials work?

A

Somewhat susceptible to penicillins (although some degree of resistance reported)

115
Q

Members of the Vibrio genus share many characteristics with what type of bacteria?

A

Enteric bacteria such as Escherichia and Salmonella

116
Q

Where are Vibrio found?

A

Water environments

117
Q

What is the most common species to infect humans?

A

Vibrio cholerae

118
Q

Vibrio causes what?

A

Cholera

119
Q

How do humans become infected with V. cholerae?

A

By ingesting contaminated food and water

120
Q

What type of communities does this occur in?

A

With poor sewage and water treatment

121
Q

What type of inoculum is required to cause the disease and why?

A

A large inoculum because the bacteria are susceptible to the acidic stomach environment

122
Q

What is the most important virulence factor of V. Cholerae?

A

Cholera toxin

123
Q

What are the symptoms of Cholera?

A
  • Some infections are asymptomatic or cause mild diarrhea
  • Can cause severe disease resulting in abrupt watery diarrhea and vomiting
  • “Rice-water stool” is characteristic
  • Results in severe fluid and electrolyte loss
  • Can progress to coma and death
124
Q

How does one diagnose for Cholera?

A

Usually based on the characteristic diarrhea

125
Q

What is the treatment for Cholera?

A
  • Fluid and electrolyte replacement

- Antimicrobial drugs are not as important because they are lost in the watery stool

126
Q

How do you prevent Cholera?

A

Adequate sewage and water treatment can limit the spread of V. cholerae

127
Q

What is the most common cause of gastroenteritis in the United States 5-7% of cases?

A

Campylobacter jejuni

128
Q

What serves as reservoirs for the bacteria?

A

Many animals

129
Q

How do humans become infected with Campylobacter jejuni?

A

Consuming contaminated food, milk, or water

130
Q

What is the most common source of infection?

A

Poultry

131
Q

What does the infection cause?

A

Produce dysenteri and frequent diarrhea that is self-limiting

132
Q

How does the bacteria spread?

A
  • Fecal-oral
  • Person-to-person sexual contact
  • Unpasteurized raw milk and poultry ingestion
  • Waterborne exposure to sick pets, especially puppies
133
Q

What would be considered an infectious dose of Campylobacter jejuni?

A

1,000-10,000 bacteria

134
Q

What is the incubation period?

A

1-7 days (up to a week)

*Probably related to the dose of organisms ingested

135
Q

A person infected with Campylobacter jejuni have what type of symptoms?

A
  • A brief prodrome of fever as high as 40°C
  • Headache, and myalgias lasting up to 24 hours
  • Crampy abdominal pain (abdominal pain and tenderness may be localized)
  • Pain in the right lower quadrant may mimic acute appendicitis (pseudoappendicitis).
  • Up to 10 watery, frequently bloody, bowel movements per day
136
Q

Patients with C. jejuni infection who report vomiting, blood diarrhea, or both tend to have what type of illness?

A

A longer illness and require hospital admission

137
Q

What organism causes most peptic ulcers?

A

Helicobacter pylori

138
Q

Does Haemophilus influenza have a capsule?

A

Yes

139
Q

What was the most common form of meningitis in infants prior to the use of an effective vaccine?

A

Haemophilus influenzae

140
Q

What disease is caused by Haemophilus aegypticus?

A

conjunctivitis with pus

141
Q

What disease is caused by Haemophilus ducreyi?

A

STD with chancre, only painful in men

142
Q

What is Bordetella?

A

Small, aerobic, nonmotile coccobacillus

B. Pertussis (the most important)

143
Q

What is B. Pertussis?

A
  • Causes pertussis, also called whopping cough
  • Most cases of disease are in children
  • Produce various adhesions and toxins, including pertussis toxin, that mediate the disease
  • Bacteria are first inhaled in aerosols and multiply in epithelial cells
  • Then progress through three stages of disease
144
Q

What are the stages of Bordetella?

A

Catarrhal
Paroxymal
Convalescence

145
Q

What is the clinical significance of B. pertussis-causes whooping cough?

A

Acquired by inhalation of droplets containing the organism
The organism attaches to the ciliated cells of the respiratory tract.
During an incubation period of 1-2 weeks, the organism multiplies and starts to liberate its toxins.

146
Q

Purtussis toxin in catarrahl contains how many A subunits and how many B subunits?

A

One A subunit and Five B subunits

147
Q

The increase of what in Catarrhal from the combined effects of pertussis toxin and bacterial adenylate cyclase inhibits host cell phagocytic cell responses and the inhibition of natural killer cell activity?

A

cAMP

148
Q

When is Dermonecrotic toxin in Catarrhal released?

A

is released upon cell lysis causing strong vasoconstrictive effects

149
Q

What is Trachael cytotoxin related to?

A

to the B. pertussis peptidogycan

-might contribute to the killing and sloughing off of ciliated cells in the respiratory tract.

150
Q

What is Lipooligosaccharide?

A

Has potent endotoxin activity

151
Q

Stage of Proxymal:

A

Lasts 4-6 weeks.
The patient has rapid, consecutive coughs with a rapid intake of air between the coughs (has a whooping sound).
mucous has accumulated, and the patient is trying to cough up the mucous accumulations.
The coughs are strong enough to break ribs!
Other symptoms due to the activity of the released toxins include:
Increased peripheral lymphocytes
Metabolic alteration such as increased insulin release and the resulting hypoglycemia
Increased capillary permeability and increased susceptibility to histamine, serotonin, and endotoxin shock

152
Q

Stage of Convalescence:

A

-Symptoms gradually subside.
This can last for months
-B. pertussis rarely spreads to other sites, but a lot of damage may occur, such as CNS dysfunction which occurs in ~10 % of the cases and is due to an unknown cause.
-Secondary infections such as pneumonia and otitis media are common.

153
Q

What is B. parapertussis?

A

causes a mild form of whooping cough

154
Q

What is B. bronchoseptica?

A

Widespread in animals where it causes kennel cough.

Occasionally causes respiratory or wound infections in humans

155
Q

What are the current treatments for Bordetella?

A

Erythromyin – only effective in early stages of the disease before the toxin(s) have been released
Vaccination P part of DPT (killed, encapsulated organism); a subunit vaccine has also been developed (purified pertussis toxin).

156
Q

What is the diagnosis for Bordetella?

A

Symptoms of pertussis are usually diagnostic

157
Q

What are the treatments for Bordetella?

A
  • Primarily supportive

* Antibacterial drugs have little effect on the course of the disease

158
Q

What is the prevention for Bordetella?

A
  • Immunization with the DPT vaccine

* Cases in the United States have increased due to a refusal by some parents to have their children immunized

159
Q

What is the classification of Francisella?

A

only 1 pathogenic species – F. tularensis

160
Q

What are the morphology and characteristics of Francisella?

A
  • Minute, pleomorphic g- rod that stains poorly
  • Staining may be bipolar
  • Nonmotile
  • Nonencapsulated
  • Won’t grow on ordinary media – requires cysteine or cystine for growth
161
Q

Where is Francisella found?

A

Found living in water as an intracellular parasite of animals.

162
Q

What are the causes of Francisella?

A
  • Spread to humans occurs mainly through the bite of an infected Dermacentor or by contact with an infected animal
  • The bacteria can spread through unbroken skin and mucous membranes, making it highly infectious
  • Tuleremia produces symptoms common to other bacterial and viral diseases and may be misdiagnosed
163
Q

How is Francisella acquired?

A
  1. Entry through skin abrasions (ulceroglandular form of the disease) - after ~ 48 hours a lesion occurs at the inoculated site.
  2. Ingestion (typhoidal form of the disease)
    •the focus of infection is the mouth, throat, and GI tract.
  3. Inhalation (pneumonic form of the disease)
    •This is the most severe form of the disease and it manifests as a pneumonia with a high mortality rate of 30% in untreated cases.
164
Q

If not contained, what can Francisella progress to?

A

Septicemia, pneumonia, and abscesses throughout the body.

165
Q

What is the antimicrobial susceptibility of Francisella?

A
  • Streptomycin or tetracycline
  • An attenuated, live vaccine that protects against the inhalation form of the disease is available for those exposed to the organism.
  • A vaccine is available to at risk individuals
  • Preventing infection is done by avoiding the major reservoirs of the bacteria.
166
Q

What type of organism is Brucella?

A

Intracellular

167
Q

What 4 species of Brucella can infect humans?

A
  • B. abortus
  • B. suis
  • B. melitensis
  • B. canis
168
Q

What is the morphology and characteritics of Brucella?

A

•Small g-cb that stain poorly

169
Q

What are the 2 antigens that are part of the LPS are recognized?

A

A and M

170
Q

Which antigen has the highest concentration of M, which causes an infection?

A

B. melitensis

171
Q

What is the virulence factor of Brucella?

A

Endotoxin

172
Q

Brucella has a tropism for what type of sugar alcohol?

A

erythritol
•Animal fetal tissues and placenta, other than those in humans, are rich in erythritol and, therefore, the organisms often cause abortions in these animals.

173
Q

What does Brucella cause?

A

Causes Brucellosis or undulent fever in man following ingestion of contaminated milk or cheese from goats (B. melitensis), cows (B. abortus), pigs (B. suis), or canines (B. canis).

174
Q

How do you treat Brucella?

A

Tetracycline for 21 days, sometimes combined with streptomycin.

175
Q

Are Pseudomonads problematic in hospitals?

A

Yes, because they can be found in numerous locations

176
Q

What does Pseudomonas aeruginosa often infect?

A

Often infects the lungs of cystic fibrosis patients

177
Q

Where does Treponema pallidum pallidum live?

A

Lives naturally only in humans as an obligate parasite

178
Q

Name the four stages of Syphilis

A

Primary
Secondary
Latent
Tertiary syphilis

179
Q

Symptoms associated with the initial infection

A

Primary

180
Q

Related to spread of the organisms away from the site of the original infection

A

Secondary

181
Q

The symptoms in primary syphilis are:

A

Chancre that should heal by itself in 3-6 weeks
painless
genitals
Mouth
Skin
rectum
Enlarged lymph nodes near the chancre the chancre

182
Q

The symptoms in Secondary Syphilis

A 
Spotted rash all over
Fever
general ill feeling
loss of appetite 
muscle aches
joint pain
enlarged lymph nodes
hair loss may occur
183
Q

The symptoms of Tertiary Syphilis

A

Cardiovascular syphilis causes aneurysms or valve disease
Central nervous system disorders (neurosyphilis)
Infiltrative tumors of skin, bones, or liver (gumma)

184
Q

How is syphilis is diagnosed

A

Primary, secondary, and congenital can be readily diagnosed with antibody tests against bacterial antigens
Tertiary syphilis is difficult to diagnose

185
Q

What is the drug of choice for treatment of syphilis?

A

penicillin

186
Q

Will penicillin work on tertiary syphilis?

Why not?

A

No

It is hyperimmune response and not an active infection

187
Q

How can you prevent syphilis?

A

Abstinence and safe sex are the primary ways to avoid contracting syphilis

188
Q

What is Borrelia?

A

Lightly staining, Gram-negative spirochetes

189
Q

Borrelia causes two diseases in humans

A

Lyme disease

Relapsing fever

190
Q

What are the 3 phases of lyme disease

In untreated patients?

A
  • In most cases an expanding red “bull’s eye” rash occurs at the site of infection
  • Neurological symptoms and cardiac dysfunction
  • Severe arthritis that can last for years
  • Pathology of this stage is largely a result of the body’s immune response
191
Q

What is the pathology of Lyme Disease?

A

The increase of cases is a result of humans coming in closer association with ticks infected with Borrelia

192
Q

What can treat the first stage of Lyme Disease?

A

Antimicrobial drugs can effectively treat the first stage of Lyme disease

193
Q

Why is treatment difficult of the later stages of Lyme Disease?

A

Treatment of later stages is difficult because symptoms result from the immune response rather than the presence of bacteria

194
Q

What are the two types of Relapsing Fever?

A

Epidemic relapsing fever

Endemic relapsing fever

195
Q

What are the Mortality Rate of Epidemic Relapsing Fever?

A

Mortality rate is 1% with treatment; 30-70% without treatment

196
Q

What transmits Epidemic Relapsing Fever?

A

Transmitted by lice!!

197
Q

What can cause Endemic Relapsing Fever?

A

Several Borrelia species can cause this disease

198
Q

How is it transmitted?

A

Transmitted to humans by soft ticks of the genus Ornithodoros

199
Q

How are the two types of Relapsing fever characterized?

A

Both types of relapsing fever are characterized by recurring episodes of fever and septicemia separated by symptom free intervals

200
Q

What is the primary method of diagnosis?

A

Observation of the spirochetes

201
Q

What can treat Relapsing fever?

A

Successful treatment is with antimicrobial drugs

Prevention involves avoidance of ticks and lice, good personal hygiene, and use of repellent chemicals

202
Q

Characteristics of Mycoplasma:

A
  1. Smallest free-living microbes
  2. Lack cytochromes, enzymes of the Krebs cycle, and cell walls
  3. Often have sterols in their cytoplasmic membranes which other prokaryotes lack
  4. Require various growth factors that must be acquired from a host or supplied in laboratory media
  5. Can colonize the mucous membranes of the respiratory and urinary tracts
203
Q

What does Mycoplasma pneumonia attaches to?

A

Attaches specifically to receptors located at the bases of cilia on epithelial cells lining the respiratory tracts of humans

204
Q

What can Mycoplasma pneumonia cause?

A

Causes primary atypical pneumonia, or walking pneumonia

205
Q

Symptoms of primary atypical pneumonia or walking pneumonia

A

Symptoms such as fever, headache, and sore throat are not typical of other types of pneumonia

206
Q

How is primary atypical pneumonia or walking pneumonia spread?

A

Spread by nasal secretions among people in close contact

207
Q
  1. Why is diagnosing Mycoplasma pneumoniae difficult?
A

Mycoplasmas are small and grow slowly

208
Q

Why is prevention of Mycoplasma pneumoniae difficult?

A

Patient can be infective for long periods of time without signs or symptoms

209
Q

Characteristics of Rickettsias

A

Extremely small
Appear almost wall-less due to small amount of peptidoglycan present
Obligate intracellular parasites-unusual as they have function genes for protein synthesis, ATP production and reproduction
Three genera cause disease in humans-Rickettsia, Orienta and Ehrlichia

210
Q
  1. Signs and Symptoms of Rocky Mountain Spotted Fever usually develop 2 to 14 days after a tick bite
A 
Chills & Fever
Severe Headache
Muscle Pain
Mental Confusion & Hallucinations
Rash
Abnormal sensitivity to light
Diarrhea
Excessive thirst
Loss of appetite
Nausea & Vomiting
211
Q

Signs and Symptoms of Endemic Typhus spread by fleas

A 
Chills
Cough
Delirium
High Fever (104 degrees F)
Joint Pain (arthralgia)
Light may hurt eyes
Hypotension
Rash that begins on the chest & spreads to the rest of the body (except palms of hands and soles of feet)
Severe headache
Severe muscle pain stupor
212
Q

Signs and Symptoms of Epidemic Typhus spread by lice

A 
Abdominal Pain
Backache
Dull red rash that spreads from the middle of the body
Extremely high fever (105-106 degrees F), may last up to 2 weeks
Hacking, dry cough
Headache
Joint Pain (arthralgia)
Nausea
Vomiting
213
Q

Characteristics of Chlamydia

A

Do NOT have cell walls- have two membranes but without any peptidoglycan between them
Grow & multiply only within the vesicles of host cells
Have a unique developmental cycle involving two forms-both forms can occur within the phagosome of a host cell

214
Q

Characteristics of Chlamydia trachomatis

A

Has limited host range-one strain infects mice, all others infect humans
Infect the conjunctiva, lungs, urinary tract, or genital tract
Enters the body through abrasions and lacerations
Clinical manifestations result from the destruction of infected cells at the infection site, and from the resulting inflammatory response.

215
Q

What two main types of diseases does Chlamydia trachomatis cause?

A

Sexually transmitted diseases- causes the most common sexually transmitted disease in the US
Trachoma-Ocular Disease-Occurs particularly in children-Endemic in crowded, poor communities with poor hygiene, inadequate sanitation and inferior medical care.

216
Q

Sexually Transmitted Diseases

A

Lymphogranuloma veneruem-Characterized by a transient genital lesion and swollen, painfully inflamed, inguinal lymph nodes
Occurs in three stages-
-Initial Stage- produces a lesion at the infection site that is a small painless, and heals rapidly
-Second Stage-buboes develop at the infection site
-Third Stage-only some cases progress to this stage-characterized by genital sores, constriction of the urethra and genital elephantiasis.

217
Q

Lymphogranuloma veneruem

A

Most infections in women are symptomatic but men may or may not have symptoms
Women can develop pelvic inflammatory disease if reinfected with C. trachomatis

218
Q

What does the trachoma disease affect?

A

The eye

219
Q

What can it cause?

A

Nontraumatic blindness in humans

220
Q

How does bacteria affect the eye?

A

Bacteria multiply in the conjunctival cell resulting in scarring

221
Q

What does the scarring cause?

A

Causes the eyelashes to turn inwards and abrade the eye eventually resulting in blindness

222
Q

Who does trachoma typically affect?

A

Children who have been infected during birth

223
Q

What else may result in the disease?

A

Infection of the eye with bacteria from the genitalia.

224
Q

How is trachoma diagnosed?

A

There must be bacterial inside cells from the site of infection.

225
Q

How is trachoma treated?

A
  • Antibiotics can be administered for genital and ocular infections
  • Surgical correction of eyelid deformities from Trachoma may prevent blindness
226
Q

How can Trachoma be prevented?

A

Abstinence and safe sex can prevent a chlamydial infection

227
Q

How can blindness be prevented?

A

By prompt treatment with antibacterial agents and preventing reinfections

228
Q

What type of bacteria is Legionella pneumophila?

A

Aerobic, slender, pleomorphic bacteria

229
Q

Where does L. pneumophila inhabit?

A

Water

230
Q

How do humans acquire the disease?

A

By inhaling the bacteria in aerosols from various water sources.

231
Q

Are L. pneumophila intracellular parasites?

A

Yes

232
Q

What does Legionnaires’ disease result in?

A

Pneumonia

233
Q

Are immunocompromised individuals more susceptible to the disease?

A

Yes

234
Q

Is elimination of the bacteria feasible?

A

No, but reducing their number is a successful control measure

235
Q

What type of bacteria is Bartonella?

A

Gram negative aerobic bacilli

236
Q

Where is it typically found?

A

It is found in animals but only cause disease in humans

237
Q

Which species are pathogenic?

A

B. bacilliformis
B. quintana
B. henselae

238
Q

What is B. bacilliformis also known as?

A

Bartonellosis-Carrion’s disease

239
Q

How is it transmitted?

A

By blood sucking sand flies

240
Q

What are the signs and symptoms of the acute phase?

A

Fever, pallor, malaise, nonpainful hepatomegaly, jaundice, lymphadenopathy, splenomegaly

241
Q

What else is this phase characterized by?

A

Severe hemolytic anemia and transient immunosuppression

242
Q

What is the case fatality rate?

A

Of untreated patients, greater than 40%, but reach 90% when opportunistic infection with Salmonella occurs

243
Q

What is B. quintana also known as?

A

Trench fever

244
Q

How is B. quintana spread?

A

From person to person by human body lice

245
Q

What may this disease result in?

A

Disease in immunocompromised patients

246
Q

How does the disease classically present?

A

As a five day fever of the relapsing type

247
Q

What is B. henselae also known as?

A

Cat scratch fever

248
Q

How is it introduced to humans?

A

Through cat scratches or bites

Micro Lecture Unit 3 (7 decks)

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