Gram Negative Flashcards by Aserah Blank

Gram (-) Diplococci that is aeorbic and can utilize maltose positive

N. Meningitidis

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Comma shaped rods that grows in alkaline media

Vibrio cholerae

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Gram negative bacilli that ferment lactose faster

Klebsiella
E coli
Ebterobacter

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Transmission of Neisseria meningitidis

Respiratory droplets
• in close quarters (camps, dormitories)
• carriage in the nasopharynx

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Encapsulated, kidney-bean shaped diplococcus

Neisseria

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Natural host of Neisseria

Only human

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Can form bactericidal and hemagglutinating antibodies

Neisseria

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Most common cause among aged 2-18 years old

Meningitis

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Clinical manifestation includes fever, headache, stiif neck and increased level of PMNs in CSF

Miningitis

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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

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Dissemination of meningococci into the bloodstream which causes from consumption coagulopathy into petechial or purpuric rash (purpura fulminans)

Mingococcemia

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Positive in Meningococci but negative in gonococci

Polysaccharide capsule

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Deficiencies in late acting complement components (C5-C9) predispose to illness that leads to cannot foem membrane attack complexes

Complement

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Dark culture specimen on blood agar that has been heated to 80°C for 15 mins

Culture (Chocolate agar)

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Prevents growth of bacteria using Thayer Martin Agar

Diagnosis of N meningitidis

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Ferment both maltose and glucose

N. Meningitidis

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Treatment of meningococcal meningitis and septicemia

Penicillin

Ceftriaxone/ cefotaxime

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Drugs for Prophylaxis of close contacts of infected persons

Rifampin/ Ciproflaxin

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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

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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

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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

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Most common anatomical site among carriers of N. miningitides.

Nasopharynx

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Which of the following opportunistic bacteria is non-motile and gram (-) bacilli?

Burkholderia
Pseudomonas
Acinetobacter
Aeromonas

Acinetobacter

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Which of the following opportunistic bacteria is non-motile and gram (-) bacilli?

Burkholderia
Pseudomonas
Acinetobacter
Aeromonas

Acinetobacter

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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

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 (Acanthamoeba and Hartmannella) 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 (Acanthamoeba and Hartmannella) 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