Gram Negative Bacteria Flashcards
Lactose-fermenting enteric bacteria
grow pink colonies on MacConkey’s agar
“Test with macConKEE’S agar”
Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia
(Lactorse is KEE)
Neisseria
Gram Negative diplococci
Ferment glucose and prduce IgA protease (SHiN)
MeninGococci ferment Maltose and Glucose, polysaccharide capsule, vaccine, resp and oral secretions, causes meningococcemia, meningitis and Waterhouse-Friderichsen syndrome
Px - Rifampin
Tx - Ceftriazone, Pen G
Gonococci ferment Glucose, STI, causes Gonorrhea, septic arthritis, PID, Fitz-Hugh-Curtis syn
Cultured on VPN media
Tx - Ceftriaxone
Haemophilus influenzae
small gram negative Coccoid Rod
haEMOPhilus causes Epiglottitis, Meningitis, Otitis media, Pneumonia.
Aerosal transmission
Type B - Encapsulated, IgA Protease (SHiN)
Cultured on Chocolate agar with factors V (NAD+) and X (hematin)
“When a child has the flu mom goes to the Five and Dime store to buy some Chocolate” (doesn’t cause the flu)
Tx- Ceftriaxone
Px - Rifampin
Legionella pneumophila
Gram negative rod. Silver Stain. Grows on Charcoal Yeast extract with Iron and Cysteine. Aerosol transmission. Detected by presence of antigen in urine.
Legionnaires’ Dz - sever pneumonia and fever
Pontiac Fever - flulike syndrome
Nosocomial with when water source is involved
Pseudomonas aeruginosa
Aerobic Gram Negative Rod. Non-lactose fermenter. Oxidase +. Blue-green Pigment (pyocyanin).
Endotoxin (fever, shock)
Exotoxin A (inact EF2)
PSEUDOmonas is assoc with wound and burn infxns, Pneumonia (CF), Sepsis, External otitis (swimmer’s ear), UTI, Drug use, Diabetic Osteomyletis, and hot tub folliculitis.
Nosocomial with respiratory therapy equipment
E. coli
Fimbriae - cystitis, pyelonephritis
K capsule - pneumonia, neonatal meningitis
LPS endotoxin - septic shock
EIEC, ETEC, EPEC, EHEC
EIEC
Invasive -> Dysentery
Invades intestinal mucosa and causes necrosis and inflamm
clinically similar to Shigella
ETEC
Traveler’s Diarrhea (Watery)
Labile Toxin/Stable Toxin
No inflamm or invasion
EPEC
Pediatric Diarrhea
No toxin. Adheres to apical surface, flattens villi, prevents absorption
EHEC
Does not ferment sorbitol
Dysentery
O157:H7 is most common
Shiga-Like toxin -> Hemoyltic-uremic syndrome (1.anemia 2.thrombocytopenia 3.acute renal failure)
Klebsiella
Fast Lactose fermenting rod Intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated. Red Currant Jelly sputum 4A's Aspiration pneumonia Abscess in lungs and Liver Alcoholics diAbetics
Salmonella & Shigella
Non-Lactose Fermenting, Oxidase negative, rods that invade intestinal mucosa and cause bloody diarrhea
Salmonella have flagella, disseminate hematogenously, animal reservoir, produce H2S (Antibiotics lengthen illness)
Salmonella typhi - typhoid fever with rose spots on abdomen, fever, headache, and diarrhea
Shigella are more virulent (ow ID50), no flagella but use actin polymerization to propel (Antibiotics shorten illness)
Campylobacter jejuni
Oxidase +, comma shaped, grown at 42oC (hot)
Major cause of Bloody Diarrhea, Guillain-Barre syndrome
Fecal-Oral thru poultry, meat, unpast milk.
“Campylobacter likes the hot campfire”
Vibrio cholerae
Oxidase +, comma shaped, grown in alkaline media
Rice-water Diarrhea via Cholera toxin (act Gs)
Endemic to developing countries
Prompt oral rehydration is necessary
Yersinia entercolitica
Mesenteric adenitis (mimics Crohn's or appendicitis) Diarrhea outbreaks in daycare centers Transmitted thru pet feces, contaminated milk, pork
Helicobacter pylori
Non-Lactose fermenting, oxidase +, urease + rod
Creates alkaline environment
Gastritis and duodenal ulcers (90%)
RF for peptic ulcer, gastric adenocarcinoma, and lymphoma
Triple Therapy - PPI (prazoles), Clarithromycin, Amoxicillin/Metronidazole
Spirochetes
spiral-shaped with axial filaments BLT. B is Big. Borrelia - only one visible with aniline dyes (Giemsa stain) Leptospira Treponema - dark-field microscopy
Leptospira interrogans
Found in water contaminated with animal urine.
Flulike symptons, jaundice, photophobia with conjunctivitis (surfers in the tropics).
Weil’s Dz (icterohemorrhagic leptospirosis) - sever jaundice, azotemia from liver and kidney dysfxn, fever, hemorrhage, anemia
Borrelia Burgdorferi
Lyme Dz
transmitted by the tick Ixodes (mice, deer)
Stage 1 - erythema chronicum migrans (expanding bulls-eye rash), flulike
Stage 2 - neurologic (Bell’s palsy) and cardiac (AV nodal block)
Stage 3 - Chronic monoarthritis and migratory polyarthritis
“BAKE a key Lyme pie”
Bell’s palsy (bilateral). Arthritis, Kardiac block, Erythema migrans
Tx - Doxycycline, Ceftriaxone
Treponema Pallidum
Syphilis
Primary - painless chancre
Secondary (Systemic) - disseminated with rash on palms and soles, condylomata lata. Can be visualized with darkfield
Tertiary - Gummas (chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis), Argyll Robertson pupil
Signs - broad-based ataxia, + Romberg, Charcot joint, Stroke without HTN
Screen with VDRL and confirm with FTA-ABS
Congenital - Saber shins, saddle nose, CN VIII deafness, Hutchinson’s teeth, mulberry molars
Gardenella vaginalis
Pleomorphic Gram-Variable Rod
Vaginosis with nonpainful gray vaginal discharge with fishy smell (clue cells)
Mobiluncus (anaerobe) is also involved
Not an STD, but assoc with sex
Tx - Metronidazole
“I don’t have a CLUE why I smell FISH in the VAGINA GARDEN!”
Rickettsia rickettsii
Pleomorphic, Obligate intracellular (need CoA and NAD+)
Rocky Mountain Spotted Fever - rash (starts on wrists and ankles and migrates inward and outward), headache, fever
Endemic to East Coast
Rickettsia typhi & prowazekii
Pleomorphic, Obligate intracellular (need CoA and NAD+)
Typhus Rash starts on Trunk and spread out (no palm or sole involvement)
typhi - endemic with fleas
prowazekii - epidemic with human body louse
Ehrlichiosis & Anaplasmosis
Tick Borne -> No Rash
Ehrlichiosis - granuloctyes with berry cluster organisms
Anaplasmosis - granulocytes with morula in cytoplasm
Coxiella burnetti
Tick feces and cattle placenta release spores that are inhaled as aerosols. No arthropod vector.
Q Fever - presents as pneumonia
Q Fever is Queer bc it has no rash, no vector, no Weil-Felix rxn, no Rickettsia name, and can survive outside
Tx - Doxycyline
you drive CARS using your palms and soles
Palm and sole rash is seen in Coxsackievirus A infxn (hand, foot, and mouth dz)
Rocky mountain spotted fever
Syphilis
Chlamydiae
Obligate intracellular organism (can’t make own ATP) Pleomorphic
Mucosal infxns
1. Elemental Body is Enfectious and Enters cells vie Endocytosis
2. Reticulate Body Replicates in cell by fission
Dx - cytoplasmic inclusions on Giemsa stain
Tx - Azithromycin or doxycycline
Chlamydia trachomatis
Obligate intracellular
Types A,B,C - chronic infxns cause blindness due to follicular conjuctivitis in Africa (ABC = Africa/Blindness/Chronic)
Types D-K - urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis (neonates acquire dz thru passage of infected birth canal)
Types L1,L2,L3 - lymphogranuloma venereum
Chlamydia pneumoniae & psittaci
Obligate intracellular
Atypical pneumonia, transmitted by aerosol
C. psittaci - notable for an avian reservoir
Mycoplasma penumoniae
No Cell Wall. Not seen on Gram Stain. Only bacterial membrane containing cholesterol. Grown on Eaton’s agar
Atypical “walking” pneumonia - insidious onset, headache, nonproductive cough, diffuse interstitial infiltrate
Most common in < 30 yo, military recruits, prisons
X-ray looks worse than patient, high titer cold agglutinins (IgM) which can agglutinate or lyse RBCs.
Tx - tetracycline, erythromycin (pen-res bc no cell wall)
