Bacterial Diseases Flashcards

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1
Q

Signs/symptoms of Infection by Escherichia coli

A
  • Tiredness, Shaking, Chills, Pain in loin, Burning sensation when peeing
  • Pale, suprapubic tenderness
  • Positive nitrite, pus cells and protein
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2
Q

Pyelonephritis

A

inflammation of the kidney

-commonly caused by bacterial infection spread up urinary tract or travelled through the bloodstream

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3
Q

Uropathogenic E. coli major cause

A

UTI in anatomically normal, unobstructed urinary tracts

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4
Q

E. coli

A

motile, nonsporing gram negative bacillus with a typical bacterial cell wall of LPS

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5
Q

What kind of flagella does E. coli have?

A

Peritrichous flagella

-posess fimbrias important in adhesion

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6
Q

Agents that cause UTI

A
  • Enterococci

- Enterobacteriacceae

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7
Q

Structure of E. coli lipopolysaccharide (LPS)

A

-lipid containing beta-hydroxy fatty acids attached to carbohydrate, core carbohydrate component consisting of monomers of different carbohydrates

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8
Q

Infection by Escherichia coli

A

entry into body, spread within body, spread from person to person

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9
Q

Why is female generally more likely to have a UTI compared to male?

A

Length of the urethra

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10
Q

In adulthood, up to ______ of females will have a urinary tract infection at some time in their lives

A

40%

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11
Q

Why is lack of estrogen risk factor for UTI in post-menopausal women?

A

microbial flora changes from one mainly of lactobacilli (Gram +) to one with gram -

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12
Q

What is a significant risk factor in hospitals for both males and females for UTI?

A

Catheterization

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13
Q

UTI clinical presentation in neonates

A

nonspecific with vomiting and fever

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14
Q

UTI clinical presentation in older children and adults

A

Cystitis ( inflammation of urinary bladder)
Dysuria (painful or difficult urination)
Suprapubic pain and fever
Hematuria (blood in urine)

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15
Q

UTI clinical presentation in elderly patients

A

Typical picture of fever, incontinence, dementia or signs suggestive of chest infection

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16
Q

UTI complications

A

renal scarring, septicemia, papillary necrosis, parenchymal abscess and perinephric abscess

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17
Q

UTI diagnosis

A
  • culturing mid-stream specimen of urine

- number of bacteria in urine greater than 10^5 CFU/ml

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18
Q

UTI related cystitis treated with

A

3 days of ATB

  • Ciprofloxacin (Cipro)
  • Trimethoprim-sulfamethoxazole (Bactrim)
  • Amoxycillin
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19
Q

Mac Conkey’s agar contains

A

carbohydrate Lactose

-allows differentiation onf Gram-negative bacteria

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20
Q

Mac Conkey’s agar

A

organisms which ferment Lactose (E. coli) produce acid-end products
-react with pH indicator and produce pink color

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21
Q

Infection by Clostridium difficlile signs

A

Chest infection, profuse watery diarrhea, abdominal pain

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22
Q

toxic megacolon

A

abnormal dilation of the colon that develops within a few days and can be life threatening

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23
Q

Beta-Lactam Antibiotics

A

Penicillins, Aztreoman, Cephalosporins, Carbapenems

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24
Q

Clostridium difficile

A

anaerobic spore-forming motile (gram + rod bacteria)

-pathogen produce toxins that can cause severe bloody diarrhea in patients treated with antibiotics

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25
Q

Clostridium difficile produces

A
  • irregular (crenated edges) white colonies in blood agar

- is saccharolytic and produces three exotoxines ( TcdA, TcdB and binary toxin)

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26
Q

Toxin A and B induce

A

glycosylation of G-proteins and ultimately affect actin polymerization leading to loss of tissue integrity

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27
Q

Third toxin

A

binary toxin that has ADP ribosylating activity

-associated with increased virulence

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28
Q

Clostridium difficile entry into body

A

following ingestion of spores from contaminated feces or environment

  • bacteria colonized mainly large intestine of GI tract
  • commensal, normally doesn’t cause disease
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29
Q

Clostridium difficile diagnosis

A

detection of toxins in feces by ELISA and GDH (glutamate Dehydrogenase)

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30
Q

Psuedomembranous colitis diagnosed by

A

colonoscopy

-raised yellowish plaques may be seen on mucosa

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31
Q

Clostridium difficile treatment

A

First line: Vanomycin or metronidazole

Alternatives: Cholestryamine, Bacitracin-fuscidic acid/rifaximin, probiotic/fecal enema, intravenous immunoglobulin

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32
Q

Fecal Microbiota Transplantation (FMT)

A

fecal transplant for multiple recurrence

-used primarily to treat Clostridium difficile-associated infection

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33
Q

Pulsed-field Gel electrophoresis (PFGE)

A

laboratory technique used to produce DNA fingerprint for bacterial isolate (group of same type of bacteria)

34
Q

Infection by Staphylococcus aureus signs

A

Septic shock, acute renal and respiratory failure

  • fever of 39.3 C
  • Arterial blood gas pO2: 89mmHg
  • WBC count: 27,000 mm3
  • gram +, catalase +, coagulase + coccus resistant to methicillin
35
Q

Methicillin-resistant Staphylococcus aureus (MRSA)

A
  • gram + cocci that grow in grape like clusters

- produce enzyme catalase

36
Q

S aureus

A

typical gram + cell wall

  • thick peptidoglycan layer
  • extensively cross-linked with pentaglycine bridges
  • secretes coagulase (binds soluble fibrinogen)
37
Q

pleural effusion

A

excess fluid that accumulates in the pleural cavity

  • fluid-filled space that surrounds the lungs
  • excess can impair breathing by limiting lung expansion
38
Q

Infection by Staphylococcus aureus entry

A
  • Requires breach in the skin or mucosa (catheter, surgical incision, burn, traumatic wound, ulceration or viral skin lesion)
  • person to person spread (direct contact or contact with fomite)
39
Q

fomites

A

an inanimate object that is capable of transmitting infectious organisms from one individual to another

40
Q

Skin infection by staphylococcus aureus

A

superficial (impetigo), infection of hair follicles (folliculitis), boils (furuncles), deeper infections (carbuncles)

41
Q

What causes carbuncles to occur?

A

When furuncles unite and extend deeper into the subcutaneous tissues forming sinus tracts

42
Q

S. aureus is a frequent cause of:

A

bacteremia

-half of instances are nosocomial

43
Q

Nosocomial

A

associated with surgical wound infection and foreign bodies such as indwelling catheters or sutures

44
Q

_______ endocarditis has a _____ mortality and may throw off _____ _______ that may infer other organs

A

S. aureus, high, septic emboli

45
Q

Pneumonia may result if

A

bacteria reach the lungs via the bloodstream or as a result of aspiration

46
Q

What may result from hematogenous spread or from a skin infection?

A

Acute and chronic osteomyelitis and septic arthritis

47
Q

S aureus secretes:

A

several toxins

-some function as superantigens

48
Q

superantigens

A

recognized by T-cells without being processed into peptides that are captured by MHC

49
Q

superantigens activate

A

T cells and macrophages

-leading to excessive production of pro-inflammatory cytokines and T cell proliferation

50
Q

superantigens cause

A

fever, diffuse macular rash, desquamation (including palms, soles), hypotension and shock

51
Q

Staphylococcal Scalded Skin Syndrome (SSSS)

A

mediated by the exfoilative toxins A and B produced by exfoliative toxins A and B produced by certain strains of S. aureus
-mainly in neonates and young children following infection of mouth, nose, throat or umbilicus

52
Q

Staphylococcal Scalded Skin Syndrome syptoms

A

large areas of skin blister and peel away

  • leaves wet, red and painful areas
  • healing occurs within 1-2 weeks
53
Q

Diagnosis of infection by staphylococcus aureus

A

microscopy: gram stain (small grape shape clusters of gram+ cocci)
culture: grow well on blood agar after 24-48 hrs at 37 C

54
Q

Staphylococci are

A

facultative anaerobes

55
Q

colonies of S. aureus are

A

large, smooth, glossy domes with an entire edge

-look golden yellow

56
Q

almost all strains of S. aureus are

A

Beta-hemolytic (complete breakdown of RBCs)

- due to secretion of cytotoxins

57
Q

mannitol salt agar

A

contains 7.5% sodium chloride and mannitol

-carbon source useful selective and differential medium to recover staphs

58
Q

Phenol red reveals colonies fermenting mannitol because

A

acid produced by colonies changes color of agar from pink to yellow

59
Q

Catalase_______ hydrogen peroxide to _____ and molecular _____

A

reduces, water, oxygen

60
Q

s aureus is coagulase

A

+

61
Q

coagulase will cause the plasma to

A

clot

62
Q

resistance to penicillin is mediated by a

A

plasmid-encoded beta-lactamase (penicillinase) which hydrolyzes the beta-lactam ring of the molecule

63
Q

MRSA

A

methicillin-resistant s aureus

64
Q

What is reserved for staphylococcal strains that are resistant to penicillinase-resistant penicillins and clindamycin?

A

vancomycin

-mainly acts by prevention of cell-wall biosynthesis of bacteria

65
Q

What may be used to treat superficial or localized skin infections caused by S. aureus?

A

mupirocin

-inhibits bacterial protein and RNA synthesis

66
Q

infection by streptococcus pneumoniae

A

fevers, shaking chills, and productive cough

  • coughing up blood-tinged sputum
  • left side chest pain when breathing or coughing
  • shortness of breath
  • BP: 140/80, respiratory rate: 24
67
Q

S. pneumoniae is one of the main causes of

A

respiratory tract infections

-most common cause of community-acquired bacterial pneumonia

68
Q

S. pneumoniae

A

gram+, catalase negative diplococcus

  • grows readily on blood agar
  • colonies gray-green color
69
Q

catalase test

A

used to distinguish streptococci (negative) from staphylococci (positive)

70
Q

polysaccharide capsule impedes phagocytosis primarily by

A

inhibiting deposition of the opsonic C3b

-capsule is most importantly virulence factor

71
Q

s. pneumoniae enters body through

A

oral-nasal route via respiratory droplets and adheres to oropharyngeal epithelium via adhesin molecule

72
Q

pneumococcal pneumonia typically presents with

A

abrupt onset of fever and shaking chills

  • majority of patients have productive cough
  • blood-tinged sputum and pleurisy (pleural infection)
  • sinusitis and otitis media
73
Q

streptococus pneumoniae diagnosis

A

microsocopy: exam sputum, blood cerebrospinal fluid, bullet shaped diplococci

74
Q

infection by neisseria gonorrhoae

A

dysuria, pus like drainage, tenderness at tip of penis, fever, shaking, chills, lower abdominal pain

75
Q

What is a reportable infectious disease by law in the US to public health authorities?

A

gonorrhea

76
Q

Gonorrhea transmission and presentation

A

gonococcus

  • sexually transmitted pathogen
  • acquired and spread horizontally by vagina, anal or oral intercourse
  • can be spread vertically from mother to baby
  • anorectal infection, pharyngeal infection, conjunctivitis, disseminated gonococcal infection
77
Q

an increased _____ load has been found in semen of men with______

A

HIV, gonorrhea

78
Q

gonorrhea in male

A

infection of genitourinary tract, urethral discomfort, pain/difficulty urinating, discharge

79
Q

gonorrhea in female

A

endocervicitis, foul-smelling vaginal discharge, urethritis, cervicitis

80
Q

neisseria gonorrhea

A

fastidious microorganism that grows on blood agar and chocolate agar

  • usually isolated on selective media (modified thayer-martin [MTM] agar)
  • gram - diplococci
  • utilized glucose only (produces acid)
81
Q

What is the only current recommended treatment for gonorrhea?

A

cephalosporins