Gram Negative Flashcards
Gram (-) Diplococci that is aeorbic and can utilize maltose positive
N. Meningitidis
Comma shaped rods that grows in alkaline media
Vibrio cholerae
Gram negative bacilli that ferment lactose faster
Klebsiella
E coli
Ebterobacter
Transmission of Neisseria meningitidis
Respiratory droplets
• in close quarters (camps, dormitories)
• carriage in the nasopharynx
Encapsulated, kidney-bean shaped diplococcus
Neisseria
Natural host of Neisseria
Only human
Can form bactericidal and hemagglutinating antibodies
Neisseria
Most common cause among aged 2-18 years old
Meningitis
Clinical manifestation includes fever, headache, stiif neck and increased level of PMNs in CSF
Miningitis
Most sever form of meningococcemia with high fever, shock, widespread purpura, disseminated intravascular coagulation, thrombocytopenia and adrenal insufficiency and bilateral hemorrhagic destruction of the adrenal glands
Waterhouse-Friderichen Syndrome
Dissemination of meningococci into the bloodstream which causes from consumption coagulopathy into petechial or purpuric rash (purpura fulminans)
Mingococcemia
Positive in Meningococci but negative in gonococci
Polysaccharide capsule
Deficiencies in late acting complement components (C5-C9) predispose to illness that leads to cannot foem membrane attack complexes
Complement
Dark culture specimen on blood agar that has been heated to 80°C for 15 mins
Culture (Chocolate agar)
Prevents growth of bacteria using Thayer Martin Agar
Diagnosis of N meningitidis
Ferment both maltose and glucose
N. Meningitidis
Treatment of meningococcal meningitis and septicemia
Penicillin
Ceftriaxone/ cefotaxime
Drugs for Prophylaxis of close contacts of infected persons
Rifampin/ Ciproflaxin
Prevention for meningococcal which contains cqpsular polysaccharide of atrains A,C, Y, and W-135 coupled to a carrier protein (diptheria toxoid). The 1st meningococcal vaccine for serogroup B
Meningococcal polyvalent vaccine
A chronic dibilitated home care Px presents with fever, cough, sputum culture, revealed gram (-) motile rods with blue pigmented colonies. What is the causative organism?
Pseudomonas
A Px had diarrhea and eventially resolved, now he presents at the ER due to ascending paralysis which started 3 days ago. The physician diagnosed him eith Guillian-Barre syndrome. What is the most likely organism of the diarrhea?
Campylobacter
Most common anatomical site among carriers of N. miningitides.
Nasopharynx
Which of the following opportunistic bacteria is non-motile and gram (-) bacilli?
- Burkholderia
- Pseudomonas
- Acinetobacter
- Aeromonas
Acinetobacter
Which of the following opportunistic bacteria is non-motile and gram (-) bacilli?
- Burkholderia
- Pseudomonas
- Acinetobacter
- Aeromonas
Acinetobacter
The virulence factor of Gonococci that enhances its ability to penetrate the mucosal lining and able to preven immunity from the previous infection.
IgA proteases
Thr hypovolemic shock in Pxs that is attributed to severe dehydration due to the massive watery diarrhea in cholera is due to?
Enterotoxin
The hypovolemic shock in Pxs that is attributed to severe dehydration due to the massive watery diarrhea in cholera is due to?
Enterotoxin
True for gonococcal infection.
- Causes foul smelling and painful among females
- Discharge is greenish and mucoid
- Discharge is perfused and yellowish non-foul smelling
- it causes non-purulent, non painful discharge to males
Discharge is perfused and yellowish non-foul smelling
The presence of purpura fulminans is an indication of what sequelae caused by the organism’s endotoxin.
Consumptive coagulopathy
Primary affects the human genital tract and transmitted thru sexual and birth canal (vertical transmission)
Neisseria gonorrhoeae
Prevention of Miningitidis infection which contains capsular polysaccharide of strains A, C, Y, and W-135 coupled to a carrier protein (diphtheria toxoid) to enhance immunogenicity
MENINGOCOCCAL POLYVALENT VACCINE
To appreciate the morphology of Legionella pneumophila, which method should be used?
- cultured with Buffered Carchoal Extract Agar
- silver staining technique
- serologic test
- gram staining technique
silver staining technique
Drug/s of choice in treating N. miningitidis
Penicillin
Ceftriaxone (cefotaxime)
Culture used for N miningitidis and the selcecrive media.
Chocolate agar
Thayer Martin Agar
Inhibits gram (+) Colistin
Vancomycin
Inhibits gram (-) excrpt Neisseria
Trimethoprim
Inhibits fungi
Nystatin
Human host only with no immunity to repeated infections
N. gonorrhoeaa
Kidney bean-shaped with concave sides facing each other forming the appearance of doughnut Gram-negative diplococci.
N. gonorrhoeae
Most common sites of inoculation of N gonorrhoeae
- Cervix (cervicitis) or vagina in the female
* Urethra (urethritis) or penis in the male
A most common cause of urethritis
Gonococcal urethritis
Urethritis and epididymitis in men (“ Tulo” in Men)
A most common cause of urethritis
Gonococcal urethritis
Urethritis and epididymitis in men (“ Tulo” in Men)
A most common cause of urethritis
Gonococcal urethritis
Urethritis and epididymitis in men (“ Tulo” in Men)
the most common cause of septic arthritis in sexually active individuals
Gonococcal arthritis
N. gonorrhoeae is the most common, the most severe form of conjunctivitis.
Hyperactive bacterial conjunctivitis
purulent conjunctivitis in newborns
Ophthalmia neonaturum
Discharge is usually mucoid/mucopurulent and the only manifestation may be crusting in the morning
Non- gonococcal urethritis
Promote adherence and invasion into epithelial cells; expression results in opaque colonies
Opa proteins
Have unique proteins that can extract iron from transferrin, lactoferrin and hemoglobin
N gonorrhoeae
Kidney bean-shaped with concave sides facing each other forming the appearance of doughnut Gram-negative diplococci
N gonorrhoeae
Treatment of N gonorrhoeae
Ceftriaxone
>plus Doxycycline (to cover for Chlamydia trachomatis – usual coinfection)
Treatment to prevent ophthalmia neonatorum.
Erythromycin ointment or Silver nitrate
Silver nitrate is no longer used because it can cause chemical conjunctivitis
Gram Negative cocci which can be naturally found in the Upper Respiratory tract
Moraxella (Branhamella catarrhalis)
Clinical manifestation: OTITIS MEDIA in children SINUSITIS BRONCHITIS PNEUMONIA COPD EXACERBATION
Moraxella (Branhamella catarrhalis)
Treatment of Moraxella infection
- Azithromycin or clarithromycin
- Amoxicillin with clavulanate
- Oral second or third generation cephalosporin
- Trimethoprim- sulfamethoxazole
Direct contact with droplets and discharges from nose and throat of an infected person.
Moraxella (Branhamella catarrhalis)
Facultative anaerobes, short, curved Gram negative bacilli which are usually motile with monotrichous (polar) flagella, Oxidase positive
Vibrio
Facultative anaerobes, short, curved Gram negative bacilli which are usually motile with monotrichous (polar) flagella, Oxidase positive
Vibrio
Comma shaped gram-negative, motile rods with a single polar flagellum. Pandemics caused by O1 biotype El tor (cholera El Tor)
V. cholerae
Producing Vibrio cholerae O1 is a well-known cause of epidemic cholera, which manifests itself by massive intestinal fluid loss and dehydration.
Cholera toxin
Producing Vibrio cholerae O1 is a well-known cause of epidemic cholera, which manifests itself by massive intestinal fluid loss and dehydration.
Cholera toxin
Match the following
V. parahemolyticus and V. vulnificus:
V. cholerae:
V. parahemolyticus:
V. vulnificus:
- saltwater
- Fecal-oral route
- Contaminated raw seafood
- Trauma to skin, especially in shellfish handlers, or by ingestion of raw shellfish
V. parahemolyticus and V. vulnificus: saltwater
V. cholerae: Fecal-oral route
V. parahemolyticus: Contaminated raw seafood
V. vulnificus: Trauma to skin, especially in shellfish handlers, or by ingestion of raw shellfish
severe diarrhea with rice water stools (no pus in stools). Washer woman’s hands sign wrinkled skin due to loss of skin turgor due to dehydration.
Complications: cardiac and renal failure, non-gap acidosis, hypokalemia
CHOLERA
Generally self-limited with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, low-grade fever
GASTROENTERITIS caused by. V. parahemolyticus and V. vulnificus
Associated with exposure to contaminated water
WOUND INFECTIONS caused by. V. vulnificus
Associated with exposure to contaminated water
WOUND INFECTIONS caused by. V. vulnificus
digest mucous layer so V. cholerae can attach to cells
Mucinase
like LT of E. coli, acts by ADP ribosylation Increase cAMP, secretion of electrolytes and water from the intestinal epithelium Secretory diarrhea
Choleragen (enterotoxin)
The flagella has (H-antigen) that has the motility
Shooting star / fast darting motility
Grows as flat yellow colonies on selective media: Thiosulfatecitrate- bile-salts-sucrose (TCBS) agar
Vibrio
Grows as flat yellow colonies on selective media: Thiosulfatecitrate- bile-salts-sucrose (TCBS) agar
Vibrio
Treatment for Cholera
Fluid and electrolyte replacement
Doxycycline, Tetracycline or Azithromycin shortens duration
Prevention of Cholera
Short term immunity using cholera vaccine may cause herd immunity
Only improvements in sanitation can lead to effective control of the disease
V. Parahemolyticus and V. vulnificus infection treatment
Minocycline plus Fluoroquinolone or Cefotaxime
Curved, comma- or S shaped, Seagull wing shape gram-negative, motile rod with a single polar, flagellum
Microaerophilic, Oxidase-positive, Catalase-positive
Campylobacter jejuni
Zoonotic of Campylobacter jejuni
wild and domestic animal and poultry; undercooked chicken
Mode of transmission of Campylobacter jejuni
(fecal-oral route) Uncooked meat (especially poultry) Unpasteurized milk
Most common cause of bacterial gastroenteritis.
Watery, foul-smelling diarrhea followed by bloody stools accompanied by fever and severe abdominal pain
May mimic ulcerative colitis
GASTROENTERITIS
Antigenic cross-reactivity between oligosaccharides in bacterial capsule and glycosphingolipidson surface of neural tissues
GUILLAIN-BARRE SYNDROME
Triad of: Urethritis, Uveitis, Arthritis
REACTIVE ARTHRITIS (REITER’S SYNDROME)
Endocarditis, Pericarditis, Pneumonia, Thrombophlebitis, Peritonitis, Meningoencephalitis
Campylobacter fetus
Gram staining of stool specimen reveals curved/comma- or Sshaped gram-negative rods with a single polar flagellum
Campylobacter jejuni
Selective media used with antibiotic at 42 C
Skirrow’s agar and Campy’s agar
Drug of choice for Campylobacter jejuni
Erythromycin - for severe disease
Fluoroquinolone
Transmission: via water aerosols, aspiration, and fecal contamination on Medical devices, Hands of healthcare workers and Healthcare giver
Major pathogen for nosocomial infections because of its ubiquitous presence in the hospital environment
Pseudomonas aeruginosa
It is the most common pathogen isolated from patients who have been hospitalized longer than 1 week, and it is a frequent cause of nosocomial infections
Pseudomonas aeruginosa
Inhabits the skin, upper respiratory tract, and colon of about 10% of people Soil, Water, Plants, Animals, Intestinal Flora, Skin
Pseudomonas aeruginosa
SKIN AND SOFT TISSUE INFECTIONS
Burn wound infections
Hot tub folliculitis: spa pools, whirl pools, or inadequately chlorinated swimming pools and hot tubs
Skin graft loss due to infection
Green nail syndrome
BONE AND CARTILAGE INFECTIONS
Puncture wound osteomyelitis
Osteomyelitis in IV drug users
EAR INFECTIONS
Most common cause of:
Otitis externa -> swimmer’s ear
Malignant otitis externa in diabetics
Chronic suppurative otitis media
(SECONDARY) PNEUMONIA
Ventilator-associated pneumonia
Necrotizing pneumonia (fleur-de-lis pattern)
High-risk CAP:
Immunocompromised
Broad-spectrum antibiotics
Steroid therapy
Structural lung lesions
• Bronchiectasis
• Cystic fibrosis
Pseudomonas aeruginosa
SKIN AND SOFT TISSUE INFECTIONS
Burn wound infections
Hot tub folliculitis: spa pools, whirl pools, or inadequately chlorinated swimming pools and hot tubs
Skin graft loss due to infection
Green nail syndrome
BONE AND CARTILAGE INFECTIONS
Puncture wound osteomyelitis
Osteomyelitis in IV drug users
EAR INFECTIONS
Most common cause of:
Otitis externa -> swimmer’s ear
Malignant otitis externa in diabetics
Chronic suppurative otitis media
(SECONDARY) PNEUMONIA
Ventilator-associated pneumonia
Necrotizing pneumonia (fleur-de-lis pattern)
High-risk CAP:
Immunocompromised
Broad-spectrum antibiotics
Steroid therapy
Structural lung lesions
• Bronchiectasis
• Cystic fibrosis
Pseudomonas aeruginosa
GASTROINTESTINAL INFECTIONS
Typhilitis (necrotizing enterocolitis)
Shanghai fever (mild form of typhoid)
Peritonitis in peritoneal dialysis patients
URINARY TRACT INFECTONS
3rd MCC of nosocomial UTIs
SEPSIS
Ecthyma gangrenosum (hemorrhagic lesions)
Febrile neutropenia
Leukemia or lymphoma post chemoradiation therapy
Severe burns
Pseudomonas aeruginosa
GASTROINTESTINAL INFECTIONS
Typhilitis (necrotizing enterocolitis)
Shanghai fever (mild form of typhoid)
Peritonitis in peritoneal dialysis patients
URINARY TRACT INFECTONS
3rd MCC of nosocomial UTIs
SEPSIS
Ecthyma gangrenosum (hemorrhagic lesions)
Febrile neutropenia
Leukemia or lymphoma post chemoradiation therapy
Severe burns
Pseudomonas aeruginosa
facilitates exotoxin transfer
Type III secretion system
lethal toxin similar to diphtheria toxin
inhibits protein synthesis by blocking EF2 causes tissue necrosis
Exotoxin A
Grown on Cetrimide agar (selective media) smooth,large,translucent,low convex, 2-4mm in diameter
Blood agar= Greenish metallic colonies
with sweet, fruity grape-like odor
produces pigments:
Pyocyanin (blue)
Pyoverdin (green fluorescent)
Pseudomonas aeruginosa
Combination of active antibiotics required because of resistance to multiple antibiotics
Antipseudomonal penicillins= (ticarcillin, piperacillin)
Penicillin + Betalactamase inhibitor= ticarcillin- clavulanate, piperacillintazobactam
3rd gen cephalosporins: ceftazidime
4th gen cephalosporins: cefepime
Monobactam: aztreonam
Carbapenems: imipenem, meropenem, doripenem, ertapenem
Fluoroquinolones: ciprofloxacin
Examples of suitable combinations:
Ceftazidime + Amikacin
Piperacillin + Amikacin
Azlocillin + Ciprofloxacin
Rifampicin is added for refractory cases
Pseudomonas aeruginosa
are aerobic, non–spore-forming, gram-negative rods
All are motile because they have polar flagella.
These organisms are catalase positive, and most are oxidase positive.
On MacConkey’s agar, they produce lactose-negative colonies
Burkholderia
Match
Burkholderia mallei-
Burkholderia pseudomallei-
Burkholderia cepacia complex-
Causes Glander’s disease
Causes Maliodosis
It is an important pathogen in patients with cystic fibrosis (CF) and in those with chronic granulomatous disease
Burkholderia mallei- Causes Glander’s disease
Burkholderia pseudomallei- causes Maliodosis
Burkholderia cepacia complex-It is an important pathogen in patients with cystic fibrosis (CF) and in those with chronic granulomatous disease
Treatment for Stenotrophomonas maltophilia
Trimethoprim-sulfamethoxazole is the antibiotic of choice, although some strains are resistant.
CLSI recommends reporting only levofloxacin, trimethoprim-sulfamethoxazole, and minocycline.
Distinguishing biochemical reactions of S. maltophilia are its negative oxidase reaction and positive DNase activity.
Colonies grow on blood agar (lavender green colonies) and MacConkey’s agar; the bacteria are nonmotile and non-fermentative.
Stenotrophomonas maltophilia
A significant nosocomial pathogen.
Risk factors for colonization or infection with this organism are mechanical ventilation, use of broad-spectrum antibiotics, catheterization, and neutropenia.
Stenotrophomonas maltophilia
Trwatment that may be susceptible to doxycycline, trimethoprim-sulfamethoxazole, quinolones, ureidopenicillins, imipenem, ampicillin-sulbactam, and ceftazidime
Acinetobacter
Acinetobacter spp. can be distinguished readily from _______ on the basis of their lack of motility, inability to reduce nitrates, and negative oxidase reaction.
pseudomonads
Nonhemolytic clinical strains of Acinetobacter
A. baumanii
Nonsaccharolytic strains (non–glucose oxidizers), Non-hemolytic Acinetobacter
Acinetobacter lwoffi
if hemolytic Acinetobacter
Acinetobacter haemolyticus
The most clinically relevant species is Acinetobacter
A. baumanii.
Gram-negative rods, non-spore forming, and facultative anaerobes
Aeromonas
They are susceptible to piperacillin, azlocillin, second and third generation cephalosporins, and carbapenems
Aeromonas
They have been associated with diarrheal disease ranging from acute diarrhea in immunocompetent adults (healthy adults) to chronic diarrhea in children, elderly, and immunocompromised individuals
Two distinct types of gastroenteritis have been associated with A. hydrophila: a cholera-like illness with a watery (rice and water) diarrhea and a dysenteric illness characterized by loose stools containing blood and mucus
Aeromonas
Clinical Manifestation includes
PONTIAC FEVER (Legionellosis)
mild flu-like illness. headache, fever, muscle aches and fatigue
self-limiting: recovery in a week is common
ATYPICAL PNEUMONIA
Accompanied by confusion, nonbloody diarrhea, hyponatremia, proteinuria, hematuria
Legionella
PREDISPOSING FACTORS: Old age; Smoking; High alcohol intake; Immunosuppression
Legionella
is a thin, aerobic, pleomorphic flagellated (Bipolar) non-spore forming bacteria, catalase (+), constitute 90% of pneumonia cases caused by legionella
Legionella pneumophila
the only virulence factor of Legionella
Endotoxin
Amoebae (AcanthamoebaandHartmannella) appear to be the natural reservoir for the organisms.
Legionella
Non-encapsulated facultative intracellular organism
Ubiquitous in man and natural water, environments
> air conditioning systems; cooling towers; Freshwater
Amoebae (AcanthamoebaandHartmannella) appear to be the natural reservoir for the organisms.
Legionella
Aerobic, motile, and nutritionally fastidious pleomorphic poorly gram-negative rods
visualized with silver stain
Serology (IFA and ELISA) Urinary antigen can be detected by radioimmunoassay with high sensitivity and specify and will remain positive for months after infection.
Urine antigen test only detects L. pneumophilia serogroup 1, but this accounts for 90% of cases
Legionella
protects bacteria from macrophage superoxide
and hydro peroxide oxidative burst
Cu-Zn superoxide dismutase and catalase-peroxidase
Can start patients with Azithromycin, Levofloxacin, Doxycycline
Legionella
Prevention of Legionella
Reducing cigarette and alcohol
Eliminating aerosols from water sources
High temperatures and hyper chlorination in hospital water supply
Legionellae can resist low levels of chlorine used in water distribution systems
