Gram Negative Bacteria of Medical Significance Flashcards
(110 cards)
1
Q
Whats the difference in the cell wall of gram pos and neg bacteria?
2
A
Thin peptidoglycan layer of the cell wall (Gram + have a much thicker peptidoglycan layer) is sandwiched between an inner cytoplasmic cell membrane and the bacterial outer wall membrane
Do not form spores
2
Q
All have a lipopolysaccharide outer membrane of cell wall. What does this often act as?
A
endotoxin
3
Q
Medically relevant gram negative cocci include three species responsible for:
A
Gonorrhea
Meningitis
Pneumonia
4
Q
Medically relevant gram negative bacilli include a multitude of species responsible for:
3
A
Respiratory illness
Urinary infections
GI problems
….and many other ailments
5
Q
If gram neg bacteria enter the blood stream, the LPS can cause a toxic reaction which results in what?
3
What could this lead to?
A
fever, increased respiratory rate, low blood pressure
endotoxic sepsis and shock
6
Q
The presence of LPS also triggers what?
A
- an innate immune response and
2. production of cytokines, which in turn, leads to inflammation, which can also produce host toxicity
7
Q
Gram Negative Cocci
2 genera?
A
Neisseria
Moraxella catarrhalis
8
Q
Where does M. cat reside (1)and what can it cause?2
A
resides in respiratory tract
-causes tracheobronchitis and pneumonia
9
Q
Describe Neisseria species?
movement?
grouping?
oxygen?
A
Non-motile, Gram negative
Usually diplococci
Aerobic
10
Q
Neisseria meningitidis causes?2
Neisseria gonorrhea causes?
A
Neisseria meningitidis - Meningitis/septiceimia
Neisseria gonorrheae - Gonorrhea
11
Q
Gonorrhea causes what in women and what in men?
1 in each and 2 shared
A
Infection of cervix
Infection of urethra (men, inflammatory response => purulent discharge)
Pain and fever
12
Q
Gonorrhea infections in men can extend to what?
In women can extend to what?
A
Male infection may extend to prostate and epididymis, causing sterility
Can extend to fallopian tubes and create scar tissue and ectopic pregnancy
13
Q
Gonnorrhea can Progresses to systemic disease:
3
Neonatuem
A
arthritis, endocarditis, meningitis
14
Q
Only natural reservoir for Neisseria meningitidis?
How is it transferred?
A
human nasopharyngeal mucosa
direct contact or droplet
15
Q
Describe the Subclinical/minimal disease of Neisseria meningitidis?
A
transient meningococcemia, short febrile flu-like episode, cleared spontaneously
16
Q
Describe Fulminant meningeal sepsis (FMS)?
Will the blood culture be pos?
Symtpoms?
9
A
massive and rapid proliferation in bloodstream
blood culture positive, usually also involves meninges
rapid clinical deterioration
Fever, severe headache, vomiting, neck/back pain, stiffness, petechial rash, altered mental status, shock, organ failure
17
Q
Describe the symtpms of meningitis?
7
A
Fever, headache, vomiting, neck/back pain, irritability, skin rash, AMS
18
Q
What does bacteria invade in menigitis?
What products cause much of the damage in menigitis?
A
bacterial invasion of meninges, rapid proliferation in CSF
Endotoxins and PMN products/inflammatory mediators
19
Q
FMS/Meningitis shock is when what happens?
4
A
endotoxin
causes capillary leakage, poor vascular tone, intravascular microthrombi, myocardial dysfunction
20
Q
FMS/Meningitis caused DIC can lead to what? 2
What two things are released that causes this?
A
endothelial damage => hemorrhages, microthrombi
Endotoxin AND cytokines
21
Q
Early diagnosis of FMS or meningitis is difficult, but crucial
What are the later stages of FMS?
What are the later stages of menigitis?
A
skin lesions appear after 6 - 12 h, easier to recognize disease
Meningitis: skin lesions 12 - 18 h after onset, no lesions in 20% of patients
22
Q
Bacteriologic diagnosis of
FMS?
Bacteriologic diagnosis of menigitis?
A
FMS: Gram stain of skin lesion biopsy specimen
Meningitis: only CSF positive
23
Q
Most important therapeutic principles of meningitis?
2
A
- therapy should never be delayed by diagnostic procedures
2. antibiotics are the most important part of treatment
24
Q
What is the first line treatment for menigitis?3
How would we treat pts in contanct with menigitis prophylactically?
A
Cefotaxime or ceftriaxone plus vancomycin
Patients in contact……………prophylactic ABX Rocephin (cefatriaxone)
25
Mortality with treatment for meningitis?
| without treatment?
26
Neurological sequelae in 8 - 20% of survivors: What are these?
3
deafness,
| mental retardation, concentration disturbances
27
Moraxella catarrhalis
is a gram negative cocci that causes infections of what?
5
1. Upper and lower respiratory
2. Middle ear
3. Eye
4. CNS
5. Joints
28
Moraxella catarrhalis infections of the upper and lower respiratory tract are particularly important in what populations?2
particularly important cause of bronchopulmonary infection in elderly,
patients with chronic lung disease
29
Moraxella catarrhalis is resistant to what?
| 3
Resistant to PCNs, SMX/TMP, tetracyclines
30
What should we treat M. Cat with?
| 4
Treated with fluoroquinolones,
most 2nd and 3rd ceph, macrolides and
Augmentin
31
Name the Aerobic Gram-Negative Nonenteric Bacilli?
| 7
1. Pseudomonas and
2. Burkholderia – an opportunistic pathogen
3. Brucella and
4. Francisella – zoonotic pathogens
5. Bordetella and
6. Legionella – mainly human pathogens
7. Alcaligenes – opportunistic pathogen
32
What are Small Gram-negative rods with a single polar flagellum?
pseudomonas
33
pseudomonas bacteria are freeliving. Where can they be found?
4
primarily in soil,
sea water, and
fresh water;
also colonize plants and animals
Important decomposers and bioremediators in nature
34
Where is pseudomonas a frequent contaminant in?
| 2
homes and clinical settings
35
What does pseudomonas produce?
| 3
Produce oxidase and catalase
| water soluable pigments
36
Pseudomonas aeruginosa
| is a common inhabitant of what?
soil and water?
37
pseudomonas is an intestinal resident in what percent of poeple?
What is it resistant to?6
10%
Resistant to soaps, dyes, quaternary ammonium disinfectants, drugs, drying
38
Pseudomonas is a Frequent contaminant of what in hospitals?
| 3
ventilators,
IV solutions,
anesthesia equipment
Opportunistic pathogen
39
Common cause of nosocomial infections in hosts with?3
burns,
neoplastic disease,
cystic fibrosis
40
Complications caused by pseudomonas cause?
| 8
```
pneumonia,
UTI,
abscesses,
otitis, and
corneal disease
Endocarditis,
meningitis, bronchopneumonia
```
41
What kind of odor and pigment does pseudomonas have?
Grapelike odor
| Greenish-blue pigment (pyocyanin)
42
What do we treat pseudomonas with?
| 6
Treated with
1. cephalosporins,
2. aminoglycosides,
3. carbenicillin,
4. polymixin,
5. quinolones (for ear infections), and
6. monobactams
43
Brucella and Brucellosis
are shaped how?
What are its two species?
Brucellosis is spread how?
How does it present?
How do we treat it?3
Tiny Gram-negative coccobacilli
```
Brucella abortus (cattle)
Brucella suis (pigs)
```
a zoonosis transmitted to humans from infected animals
Fluctuating pattern of fever……weeks to a year
UNDULANT FEVER
Treated with combination of tetracycline and rifampin or streptomycin
44
The bacteria can spread to humans with contact with what?
| 3
1. infected meat or
2. the placenta of infected animals, or from
3. unpasteurized milk or cheese.
45
Brucellosis in humans is usually associated with the consumption of what?
Clinically manifests how?
unpasteurized mildk and soft cheeses made from the milk of infected animals.
Can be insidious and may present in many atypical forms
UNDULANT FEVER
but may persist and progress to a chronically incapacitating disease with severe complications.
46
Francisella tularensis and Tularemia is shaped how?
How is it transmitted?3
Clinical manifestations?
10% death rate in which forms? 2
Treatment?3
facultative intracellular coccobacillus
a zoonotic disease. Transmitted by contact with infected animals, water and dust or bites by vectors
Headache, backache, fever, chills, malaise and weakness
in systemic and pulmonic forms
Tx: gentamicin or tetracycline
Attenuated vaccine
47
Bordetella pertussis
shape?
What does it cause?
Who is it most dangerous in?
Transmission?2
Minute, encapsulated coccobacillus
Causes pertussis or whooping cough, a communicable childhood affliction
Acute respiratory syndrome
Often severe, life-threatening complications in babies
Reservoir – apparently healthy carriers
Transmission by direct contact or inhalation of aerosols
48
Bordetella pertussis
virulence factors?
2
1. receptors that recognize and bind to ciliated respiratory epithelial cells
2. toxins that destroy and dislodge ciliated cells
49
What is the pathology of Bordetella pertussis?
Treatment?
Loss of ciliary mechanism leads to buildup of mucus and blockage of the airways.
Treatment- macrolides….Azithromycin
50
Legionella pneumophila and Legionellosis is widely distributed where?
Tranmitted?
They live in close association with what?
Other names for Legionella pneumophila and Legionellosis? 2
Who is it most prevavalent in?
Its a nosocomial disease in who?
water
Organisms inhaled in aerosolized mist
Live in close association with amoebas
Legionnaires disease and Pontiac fever
Most prevalent in males over 50
Nosocomial disease in elderly patients
51
Clinical manifestations of Legionella pneumophila and Legionellosis?
5
Fatality Rate?
What should we treat with?
```
Fever,
cough,
diarrhea,
abdominal pain,
pneumonia
```
fatality rate of 3-30%
Treat with azithromycin
52
What is The Most Prevalent Enteric Bacillus?
Most common aerobic and non-fastidious bacterium in gut?
Escherichia coli
Its needs are few
53
Some E. Coli have developed virulence through ?
| 2
plasmid transfer, others are opportunists.
54
Enterotoxigenic E. coli causes what?
Due to what?
What is a characteristic of the structure of this E. Coli?
severe diarrhea
due to heat-labile toxin and heat-stable toxin – stimulate secretion and fluid loss;
also has fimbriae (attachment pili)
55
Enteroinvasive E. coli causes what?
inflammatory disease of the large intestine.
56
Enteropathogenic E. coli linked to what?
wasting form infantile diarrhea
57
Enterohemorrhagic E. coli, O157:H7 strain, causes ?
| 2
hemorrhagic syndrome and kidney damage
58
Greatest cause of mortality among babies?
Pathogenic strains frequent agents of infantile diarrhea
59
Causes ~70% of what?
| Causes 50-80% of what?
traveler’s diarrhea
| UTI
60
What is Coliform count?
indicator of fecal contamination in water
61
Most strains of E. Coli will respond to what?
| 3
SMX/TMP, nitrofurantoin, fluoquinolones
62
Klebsiella pneumoniae is a normal inhabitant of where?
What should we know about its structure?
What does it cause?5
normal inhabitant of respiratory tract,
has large capsule,
```
cause of
nosocomial pneumonia, meningitis,
bacteremia,
wound infections and
UTIs
```
63
Enterobacter sp. infects what?2
UTIs, surgical wounds
64
Serratia marcescens produces what?
Causes what5
produces a red pigment;
```
causes
pneumonia,
burn and wound infections, septicemia and
meningitis
UTIs
```
65
Citrobacter sp. cause what?
| 2
opportunistic
| UTIs and bacteremia
66
Yersenia Pestis (Plague) is spread by what?
What areas are hardest hit right now?
fleas through rodents
Eastern African nations are hardest hit.
67
Yersinia pestis and Plague
enteric or nonenteric?
Shape?
Virulence factors?3
nonenteric
Tiny, Gram-negative rod, unusual bipolar staining and capsules
1. capsular and envelope proteins protect
against phagocytosis and foster intracellular growth
2. coagulase,
3. endotoxin, murine toxin
68
Describe the pathology of Yersinia pestis?
Where does it replicate?
What does this cause and what does it block?
bacteria replicates in gut, coagulase causes blood clotting that blocks the esophagus;
flea becomes ravenous
69
Where does the plague enter after the flea bite?
What does this cause and what is it called?
lymph, causes necrosis and swelling called a bubo in groin or axilla
70
How does the plague become systemic?
| 2
1. Septicemic – progression to massive bacterial growth; virulence factors cause intravascular coagulation subcutaneous hemorrhage and purpura – black plague
2. Pneumonic – infection localized to lungs, highly contagious;
fatal without treatment
71
Diagnosis of plague depends on what?
3
Treatment?
4
How do we prevent it?2
history, symptoms, and lab findings from aspiration of buboes.
streptomycin, tetracycline or chloramphenicol
vaccine avilable
Prevention by quarantine and control of rodent population in human habitats
72
Yersinia enterocolitica is found where?
How does this infect the host?
How do they avoid the host defenses?
Clinical manifestation can resemble?
domestic and wild animals, fish, fruits, vegetables, and water
bacteria enter small intestinal mucosa, some enter lymphatics and
survive in phagocytes;
inflammation of ileum can mimic appendicitis
73
Y. pseudotuberculosis clinically manifests how?
| 2
localized tissue necrosis and granulomas in the spleen, liver and lymph nodes
TB symtpoms
74
Y. enterocolitica causes what?
more lymph node inflammation
75
Pasteruella multocida
(Avian Cholera) found in what?
What kind of infection is it in humans?
How is it transmitted and where does it spread (3)?
Who is at greatest risk
How do we treat?
normal flora in animals
-Follows bird migration
Opportunistic infections in humans
Animal bites or scratches cause local abscess that can spread to joints, bones, and lymph nodes.
Immunocompromised are at risk for septicemia and complications.
Treatment: penicillin and tetracycline
76
Haemophilus
shape?
What kind of agar does it grow on?
tiny Gram-negative pleomorphic rods
Chocolate agar
77
H. influenzae causes what?
6
What has really helped with this infection?
```
acute bacterial meningitis, epiglottitis,
otitis media,
sinusitis,
pneumonia, and
bronchitis
```
subunit vaccine Hib
78
H. aegyptius causes?
–conjunctivitis, pink eye
79
H. ducreyi causes?
STD
80
H. parainfluenzae and H. aphrophilus are find where normally (2) and what does it cause when it becomes pathogenic?
normal oral and nasopharyngeal flora;
infective endocarditis
81
What do you treat H. Flu with?
| 5
Treated with
amoxicillin,
azithromycin,
cephalosporins, fluoroquinolones and clarithromycin
82
Most pathogenic anaerobes are usually commensals and originate where?
Predisposing Conditions?4
Originate from our own flora
```
1. Breeches in the mucocutaneous barrier
→ displace normal flora
2. Compromised vascular supply
3. Trauma with tissue destruction
4. Antecedent infection
```
83
Clues to Anaerobic Infection
| 6
1. Infections in continuity to mucosal surfaces
2. Infections with tissue necrosis and abscess formation
3. Putrid odor
4. Gas in tissues
5. Polymicrobial flora
6. Failure to grow in the lab
84
Classification of bacteria based on previous experiments allowing fast identification is called what?
What other tool is used in diagnosis of anaerobes?
API SYSTEM
GAS CHROMATOGRAPHY
85
Bacteroides fragilis
is most noted when?
Does it form spores?
Major disease causing strict anaerobic after abdominal surgery
no
86
Describe how Bacteroides fragilis evades body defenses?
| 3
Prominent capsule
- anti-phagocytic
- abscess formation
87
Bacteroides fragilis has an endotoxin affect but low toxicity. Why?
structure different than other lipolysaccharide
88
A leading cause of bacterial diarrheal illness?
How is it transmitted?
What is this bacteria associated with? 3
What should we treat with (what is it becoming resistant with)?
Campylobacter jejuni
oral/fecal route, ingestion of contaminated food and water, uncooked meat
Associated with feed lots, chicken houses, raw milk
Treated with azithromycin, increasing resistance to fluoroquinolones
89
What is Borrellia burgdorferi?
Early symtpoms include?4
(whats the buzz word?)
Lyme disease
fever, headache, and fatigue, bull's eye rash
90
If lyme disease is left untreated later symptoms may involve what?
3
Usually treated by what well?
the joints, heart and central nervous system.
DOXY or Amox (2-4 weeks)
91
How do we diagnose Lyme?
| 3
Unique bull’s eye rash
Elisa
Western Blot
92
What should we treat Chlamydia trachomatis with?
3 options
What is a complication that could arise?
Treat both partners with azithromycin,
doxycycline or
ofloxocin
blindness
93
What is Lymphogranuloma venereum(LGV)?
What system does it affect?
Uncommon sexually transmitted infection caused by three invasive serovars of Chlamydia trachomatis
Chronic long term infection of the lymphatic system
94
Symptoms of Lymphogranuloma venereum(LGV)?
| 6
1. Swollen inguinal nodes
2. Drainage through the skin from buboes or abscesses in inguinal nodes
3. Painful bowel movements (tenesmus)
4. Small painless sore on the genitals
5. Swelling of the labia
6. Blood or pus from the rectum
95
HOw do we Lymphogranuloma venereum(LGV)?
How do we treat?
3 options
Diagnosis usually made serologically and by exclusion of other causes of inguinal adenopathy or genital ulcers
doxycycline, erythromycin, azithromycin
Buboes may require incision and drainage
96
Lymphogranuloma venereum(LGV) prognosis is more favorable with?
Untreated chronic condition may cause?
Prognosis more favorable with early treatment
Untreated chronic condition may cause fistulas of the penis, urethra, vagina, uterus, rectum
97
Psittacosis is transmitted how?
Symptoms in humans range from what?2
zoonotic disease caused by Chlamydia pssitaci, contracted from parrots, pigeons, ducks, chickens, gulls
range from unapparent to systemic illness with severe pneumonia
98
Psittacosis may mimic what?
What are the symptoms?
7
As it progresses what does it mimic?
```
May mimic typhoid in early stages:
high fever,
arthralgias,
diarrhea,
conjunctivitis,
epistaxis and
neutropenia,
splenomegaly
```
pneumonia as it progresses: dyspnea, high fever, cough, patchy infiltrates or whiteout on CXR
99
Psittacosis diagnosis. What is key??
3
Treatment?
1. Diagnosis: exposure history is paramount!
2. Microbiological cultures from respiratory secretions or
3. serology from blood cultures
Doxycycline and chloramphenicol
100
What are the two types of Relapsing Fever?
What bacteria is it caused by?
Where is each one found most and which one is more severe?
What are the symtpoms?
Two types: tick borne (TBRF) and louse borne (LBRF)
Caused by Borellia spirochetes
TBRF occurs in western US, linked to sleeping in rustic, rodent infested cabins in mountainous areas
LBRF is transmitted by the human body louse and is generally restricted to refugee settings in third world. Occurs in epidemics, more severe than TBRF
Flu-like symptoms: sudden fever, chills, headaches, arthralgias, nausea. May develop a rash
101
HOw do we diagnose and treat relapsing fever?
2
1
One big thing to remember
Diagnosis on blood smear…spirochetes
Treatment: doxycycline.
May cause Jarisch-Herxheimer reaction in over half of those treated
102
Describe the strcuture of Salmonella sp.?
Motile, flagellated gram-neg
103
What can Salmonella sp. cause? 2
Whats the most common form?
Whats the main reservoir and how can it spread?
Common Salmonella gastroenteritis (diarrhea, abdominal cramps, fever) to enteric fevers (including typhoid fever) which can be life threatening
Most common form AKA “food poisoning” presents with uncomplicated gastroenteritis, usually self-limited disease
animals are main reservoir, usually food borne illness, can spread from person to person
104
Enteric Typhoid Fever-severe systemic disease, any species of salmonella may cause, S. typhi most studied.
What are the symtpoms? 6
How do we diagnose?3
How should we treat?3
N/V/D
septicemia
Fever, anorexia, headache, myalgias
Dx: stool and/or blood cultures, serology for antibodies
Often fatal if not treated
Replace fluids by oral or IV
Pain control and treating nausea and vomiting
Antibiotics…..ciprofloxacin
105
What is Shigella (clinical manifestations)?
What demographic is it commonly seen?
How is it transmitted?
Diagnosis?
Treatment?3
Intestinal disease
Bloody diarrhea, may have abdominal pain or cramps, fever
children 2-4
Passed through direct contact with stool
Dx: stool studies
Replace lost fluids, water or Pedialyte, may need IV fluids
Increasing resistance to abx…. ciprofloxocin or cefixime should be used if abx indicated
106
Vibrio sp. has two distinct groups?
Most non-cholera vibrio infections are associated with what?
Cholera infections
Non-cholera
improperly cooked contaminated food or eating raw shellfish
107
Non-cholera (vibro) wound infection or septicemia will need what for treatment?
doxycycline or a quinolone, aggressive fluid replacement, vasopressors for hypotension, fasciotomy, debridement of infected wound
108
Vibrio cholerae
buzzword?
Treatment?
profuse watery diarrhea
doxycycline or a quinolone, aggressive fluid replacement
109
Acinetobacter baumanni buzzword?
| 3 things
Commonly isolated from the hospital environment and hospitalized patients
Often cultured from sputum, respiratory secretions, wounds, urine….colonization vs infection
HOSPITAL ACQUIRED OFTEN
CULTURED FROM SECRETIONS
ICU
110
Acinetobacter baumanni treatment?
Multi-drug resistance……including carbapenems
