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Diagnostic Micro Exam 1 > Alpha & Non-hemolytic Streptococcus > Flashcards

Alpha & Non-hemolytic Streptococcus Flashcards

0
Q

What indicates inflammation from Strep pneumoniae?

A

C substance in the cell wall can elicit a C-reactive protein in the patient
Non-specific & only indicates inflammation

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1
Q

What is Streptococcus pneumoniae referred to & what is it?

A

Pneumococcus

Pathogen that causes pneumocccoccal pneumonia & meningitis

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2
Q

What is S. pneumoniae famous for?

A

A capsule - virulence factor

50 types

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3
Q

What is used to serotype the bacteria S. pneumoniae?

A

The Neufield test

Antisera & capsule will cause a swelling in the Quellung reaction

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4
Q

What does S. pneumoniae cause?

A

Pneumonia, sinusitis, otitis media, bacteremia, & meningitis
Ear infections in children over 3
Pneumonia in the elderly

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5
Q

How does one get pneumonia & what are their risk factors?

A

Patient must already by colonized & not have an antibody to the strain
Immunosuppressed - alcoholism, anesthesia, viral infections
Can lead to lobar pneumonia

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6
Q

What is effusion & pleural effusion?

A

Collection of serous fluid between an organ & the lining of the body cavity
Pleural effusion is effusion around the lungs

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7
Q

What can pneumonia be accompanied by?

A

A pleural effusion

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8
Q

Pneumonia can have several effusions which are?

A

Exudate
Transudate
Empyema

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9
Q

What is exudate?

A

Effusion that is caused by infection or malignancy & has pus (WBC)
Increased LD - lactate dehydrogenase
Increased protein

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10
Q

What is transudate?

A 
Effusion that is caused by hydrostatic pressure
Watery
Low WBC
Low LD
Low protein
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11
Q

What is empyema?

A

Collection of purulent fluid in the pleural space between the lung & chest wall
Sterile empyema has no bacteria in it
Fluid may be infected or sterile

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12
Q

What are the characteristics of pneumococcal pneumonia, meningitis, & septicemia?

A

Mortality rates are high if untreated & still can be fatal if treated
Meningitis can follow otitis media & pneumonia
CSF gram stain reveals WBC & characteristic gram positive pairs - “lancet shaped pairs”
Blood cultures are positive & performed when sputum & CSF are collected
Penicillin is the drug of choice - some strains are resistant

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13
Q

What are the types of vaccinations for pneumococcal pneumonia, meningitis, & septicemia?

A

PCV7

PS23

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14
Q

What is PCV7?

A

Pneumococcal conjugate vaccine 7
Approved for children & part of normal pediatric care
13 valent product for children

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15
Q

What is PS23?

A

23-valent vaccine used for adults

Recommended for elderly with cardiac or pulmonary disease & for asplenic individuals

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16
Q

What are the laboratory diagnosis of Strep pneumoniae?

A

Specimens - sputum, blood, CSF
Sputum is cultured to BAP in CO2, MAC & CNA, & gram stained
Beta hemolytic
Colonies - umbilicate or mucoid
MAC - no growth
CNA - growth
Distinguishes from other alpha strep using optochin & bile solubility

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17
Q

Where are the oldest colonies of S. pneumoniae?

A

In the center

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18
Q

How do we differentiate green streps (what tests)?

A

Optochin - P disk; ethylhydrocupreine HCl
Bile solubility - sodium desoxycholate
Colony morphology
Gram stain - gram positive lancet shaped pairs & chains (capsule)

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19
Q

What is endocarditis?

A

Infection of the valves of the heart
Associated with transient bacteria
Those at risk have hematologic malignancies, damaged heart valves (rheumatic fever)

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20
Q

What are the characteristics of Viridans Streptococci?

A

Normal flora in the URT, female genital tract, & GI tract
Many require CO2 for growth
Are oropharyngeal normal flora which can be opportunistic pathogens
Viridans strep is the most common cause of bacterial endocarditis

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21
Q

What does capnophilic mean?

A

Grows better in carbon dioxide

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22
Q

Strep viridans is not S. pneumoniae because of?

A

It’s green strep without Lancefield group antigens

23
Q

What are oropharyngeal commensals of Strep viridans?

A 
Sub acute bacterial Endocarditis
Meningitis
Abscesses
Osteomyelitis
Epyema
24
Q

What are the species of S. viridans?

A 
Angiosus group
Mitis group
Mutans group
Salivarius group
Bovis group
25
Q

What are the types of oral infections that are caused by S. viridans?

A

Gingivitis
Dental caries - cavaties
Oropharyngeal abscess

26
Q

What are the laboratory tests for S. viridans?

A

All viridans are PYR positive & LAP positive

Multitest panels can be used to speciate them

27
Q

What is the most commonly isolated viridans group?

A

S. mutans
Usually from oral cavity
Primary contributor to dental caries & bacteremia

28
Q

What will viridans strep be seen as in cultures?

A

Throat culture as small green colonies in the background

Normal flora

29
Q

What two types of strep bacteria are not green?

A

Enterococcus & group D strep

30
Q

What are enterococci?

A

Normal flora in the intestines

Frequent causes of nosocomial infection, especially UTI, then bacteremia, & endocarditis

31
Q

What are common species of enterococcus & group D strep?

A

E. faecalis & E. faecium

32
Q

What type of lancefield antigen do enterococcus & group D strep have?

A

Antigen D

33
Q

What type of hemolysis do enterococcus & group D strep have?

A

Usually hemolytic

Can be alpha or beta

34
Q

What type of pseudo-catalase reaction do enterococcus & group D strep?

A

Weak

35
Q

What type of conditions do enterococcus & group D strep grow under?

A

Bile
High salt
High temperature
Alkaline conditions

36
Q

What group are group D strep a part of?

A

Streptococcus bovis

37
Q

What are the strep members of the strep bovis group?

A

S. equinus
S. gallolyticus
S. infantarius
S. alactolyticus

38
Q

What are the laboratory diagnosis for Enterococcus?

A

Urine cultures on BAP & MAC with calibrated loop to count colonies
Colonies grow in CO2 but don’t require it
Blood cultures are their own collection media
Bile esculin - positive
Grow in high salt broth
PYR - positive

39
Q

What is esculin hydrolysis?

A

Ability to hydrolyze esculin
Characteristic of enterococci & group D strep
Some S. viridans do this

40
Q

What are the two results of bile esculin?

A

Black - positive
Growth - positive
No growth - negative

41
Q

What does 6.5% NaCl broth do?

A

Distinguishes between enterococcus & group D strep
Tubes will get cloudy or stay clear
No color is used for evaluation

42
Q

How are enterococcus species differentiated?

A

Based on carbohydrate & amino acid usage
Motility
Ability to grow in the presence of tellurie

43
Q

What are the motile forms of enterococcus?

A

E. faecalis - UTI
E. faecium
E avium
E. durans

44
Q

What type of enterococcus is the only one to grow in the presence of tellurite?

A

E. faecalis

45
Q

What are the components of antimicrobial resistance to aminoglycosides?

A

Enterococcus is resistant to several antibiotics
6 vancomycin resistant phenotypes VanA - VanE & VanG
˜2% of E. faecalis & 60% E. faecium found in blood are vancomycin resistant - VRE

46
Q

What is Van A?

A

Inducible

Carried on a transposon & confers a high level of resistance to vancomycin & teicoplanin

47
Q

What is VanB?

A

Chromosomal
Has variable levels of resistance to vancomycin
Susceptible to teicoplanin

48
Q

What are two types of nutritionally variant strep?

A

Abiotrophia & granulicatella spp.
Not typeable by lancefield typing
Growth as satellites & require SH for growth

49
Q

What do nutritionally variant strep cause?

A

Bacteremia, endocarditis, otitis media

Very antibiotic resistant, may require surgery

50
Q

What is the typical presentation of nutritionally variant strep?

A 
Fever
Collect blood cultures
Tubes monitored under CO2 for growth
Gram positive
S. aureus is streaked to see if they grow in satellites around it
51
Q

What types of nutritionally variant strep organisms are grown from supplemented media?

A

Pyridoxal-dependent
Vitamin B6 dependent
Thiol dependent
Staph aureus streak plates

52
Q

What are some strep like organisms?

A

Aerococcus
Gemella
Lactococcus

53
Q

What is LAP leucine aminopeptidase?

A

Enzyme that cleaves peptide bonds, especially leucine
Substrate is leucine-B-napthylamide which is hydrolyzed to B-napthylamine
Red - positive
PYR similar

54
Q

What are characteristics of aerococcus?

A 
Gram-positive cocci that form tetrads
Alpha hemolytic - resemble viridans group
Usually a contamininant
PYR - positive
Salt tolerant - 6.5% NaCl
Bile esculin variable
LAP - negative
55
Q

What are lactococcus?

A

Similar to enterococci

Pattern of carbohydrate fermentation is used to identify & distinguish them from enterococci

56
Q

What are characteristics of gemella?

A

Similar to viridans
Decolorize easily
May look gram negative cocci in pairs, tetrads, clusters or chains

Diagnostic Micro Exam 1 (6 decks)

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