Gram negative bacteria disease Flashcards
Lactose fermenting enterics
Grow pink colonies on MacConkey’s agar (Lactose is KEE)
Citrobacter, klebsiella, E Coli, enterobacter and serratia
“Test MacConKEE’S agar”
EMB agar: lactose fermenters grow as purple/black
Ecoli grows purple colonies with a green sheen.
Penicillin and gram negative bugs
Gram negatives are resistant to penicillin G but may be susceptible to penicillin derivatives, such as ampicllin and amoxicillin
Neisseria
Gonococcis: no capsule, gonorrhea, septis arthritis, neonatal conjunctivitis, PID and Fitz Hugh Curtis syndrome, treat with ceftriaxone and azithro/or doxy
Meningococcus: capsule, maltose fermenter, vaccine but not for type B, Waterhouse-Friderichsen syndrome, prophylaxis with rifampin, cipro, ceftriaxone in close contact, treat with penicillin G or cetriaxone
H influenza
HaEMOPhilus: epiglottitis, menigitis, otitis media, and pneumo.
Produce IgA protease
Culture chocolate with V and X, can be grown with S aureus, which provides factor V.
Treat meningitis with ceftrixaone,
Rifampin prophylaxis in close contact.
Vaccine contains B capsular polysaccharide t diphtheria toxoid.
Legionella pneumophilia
Legionanire’s disease:severe pneumon, fever, GI, and CNS
Pontiac fever: mild flu like syndrome
Gram negative rod: gram stains poorly: use SILER
Grow on charcoal yeast with iron and cysteine.
Detect urine atnigen.
Treat with macrolides or quinolone
???Lab shows hyponatremia
Pseudomonas
PSEUDOmonas: pneumo(in CF), sepsos (black lesions on skin), external otitis (swimmer’s year), UTI, Drg use and diabetic osteomyelitis and hot tube folliculitis
Aerobic gram negative rod, non lactose fermentaing, oxidase positive.
Produces endotoxin (fever, shock), and exotoxin A (inactivates EF2)
Treat with aminoglycoside plus extended penicillin (piperacillin, ticarcillin)
Think pseudomonas in BURNT victims.
AERuginosa: AEROBIC and ARUGLULA (green)
E coli virulence factors
E coli virulence factors:
Fimbriae: cystitis and pyelonephritis
K capsule: pneumonia, neonatal meningitis
LPS endotoxin: septic shock
E coli strains
EIEC: invade intestinal mucosa and causes necrosis and inflam. NO toxin produced. Clinically similar to Shigella. “Invading dysentery”
ETEC: labile toxin/stable toxin. No infmallation or invasion “traveler’s diarrhea”
EPEC: no toxin, adhere to apical surface, flattens villi, prevents absoprtion. “diarrhea usually in Pediatrics”
EHEC: O157:H7 the most common serotype, produces SLT and HUS syndrome (anemia, throbocytopenia, acute renal failure), endothelium swells and narrows lumen, leading to mechanical hemolysis and reduced renal blood flow, damage endothelium consumes platelets. Dysentery (toxin alone causes necrosis and inflammation). DOES NOT FERMENT SORBITAL (distinguishes from other E coli)
Klebsiella
Lobar pneumo in alcoholic and diabets when aspirated
Very mucoid coloniescaused by abundant polysaccharide capsules: RED currant jelly. Also nosocomial UTI
4As: aspiration pneymo, abscesses in lungs/liver, alcoholics, diAbetics
Salmonella vs shigella
Salmonella: flagella (salmon swim), disseminate hematogenously, animal reservoirs, produce hydrogen sulfide, antibiotics may prolong symptoms, invade musoca and causes MONOCYTIC response (intracellular), can cause bloody diarreha
Shigella: no flagella, cell to cell transmission, no hematogenous spread. Only reserve in humans and primates, does NOT produce hydrogen sulfide, antibiotics prolong excretion of organisms in feces, invades musoca and causes PMN response (extracellular), OFTEN cause bloody diarrhea.
Both do NOT ferment lactose and oxidase negative.
Salmonella typhi: causes typhoid fever, only in humans, red spots on the abd, fever, headache, diarrhea. Can remain in gallbladder and cause a carrier state.
Campylobacter jejuni
Major cause of bloody diarrhea, esp in children.
Fecal-oral transmission through foods such as poultry, meant, unpasteurizing milk
Comma shaped, oxidase positive, grows at 42C
“campy likes the hot camp fire”
Antecedent to Guillian Barre syndrome and reactive arthritis.
Vibro cholerae
Rice water stool due to Gs activation
Comma shaped oxidase positve, grows in alkine media
Endemic to developing countries, prompt rehydration is necessary.
Yersinia enterocoliti
Transmitted from pet feces (puppies), contaminated milk, or pork.
Causes mesenteric adenitis that can mimic CROHN’s or appendicitis.
H pylori
Gastritis and 90% of duodenal ulcers Curved gram negative rod Ureas positive Creates alkaline environment Most common initial tx: PPI, clarithromycin, amoxicillin or metronidazole.
Spirochetes
BLT: borrelia, leptospira, treponema
Borrelia is BIG; can be visualized by aniline dyes (Wrights or Giemsa) in light.
Treponema visualized by dark-field.
Leptospira interoggans
Found in water contamined with ANIMAL URINE.
Causes leptospirosis: flu like, jaundice, photophobia, with conjunctivitis.
Prevalent in surfers in tropics “Hawaiian surfers who touch animal urine”
***Weil’s disease: icterohemorrhagic heptospirosis: severe form with jaundice and azetemia from liver and kidney dysfunction; fever, hemorrhage and anemia.
Lyme disease
Burrelia burgdorferi, transmitted by tick Ixodes (also vector for Babesia).
Natural reservor in mouse.
Common in northeastern US
Treat with doxi or ceftriaxone
3 stages:
1) erythma chronicum migran: bulls eye, flu like
2) neurologi: facial nerve palsy, and cardiac (AV nodal block)
3) MSK (chronic monarthritis and migratory polyarthritis), neurologic (encephalopathy and polyneuropathy) and cutaneous manifestations.
FAKE a key LYME pie: Facial nerve palsy; typically bilateral Arthritis Kardiac block Erythema migrans
Syphilis
1’ painless chancre, screen with VDRL and confirm with FTA-ABS
2’ secondary=systemic, disseminated with constitutional sympts, maculopapular rash (palms and soles), condylomata lata. scree with VDRL and confirm with FTA-ABS
3’ Gummas (chronic granulomas), aoritis (vsava vasorum destruction), neurosyphilis (tabes dorsalis), argyll Roberson
Signs: broad based ataxia, positive rombergs, charcot joint, stroke withy HTN. Test spinal fluid with VDRL.
Congenital syphilis: saber shins, saddle nose, CN VIII deafness, Hutchinson’s teeth, mulberry molars.
Argyll Robertson pupil
Argyll Robertson pupil constriction with accomondation but not reactive to light; 3’ syphilis.
Prostitute’s pupil: accomondates but does not react
VDRL false positives
Non specific antibodies that react with beef cardiolipin
Viral infections(mono, hepatitis), some drugs, rhumatic fevers, SLE and leprosy
VDRL: virus, drugs, rhuematic, lupus/leprosy
Jarisch-Herxheimer reaction
Flu like symptom immediately after Abx started
due to killed bacteria release pyrogens.
Rickettsia and vector born illness
Rash producing
All treat with doxy
Rash producing:
Rocky Mountain spotted fever (tick): Rickettsia rickettsii, broadly distributed in US. Rash typically start at wrists and ankles and then spread to trunk, palms, and soles.
Richettsiae are obligate intracellular with need CoA and NAD+
Typus:
endemic (fleas) - R thyphi
epidemic (human body rouse) = R prowazekii, rash starts CENTRALLY and spreads out, sparing palms and soles.
Classic triad: headache, fever, rash
“Rickettsiii starts on wRist, Typhus on the Trunk”
Palms and sole rashes in Coxaskies A (HFM disease), Rocky mountain spotted fever, and Secondary syphilis
“You drive CARS using your palms and soles”
Rickettsia and vector born illness
No rash producing
All treat with doxy
Ehrlichiosis (tick): monocytes with morula (berry like inclusions) in cytoplasm
Anaplasmosis (tick): granunocytes with morula in cytoplasm
Q fever (tick feces and cattle placenta release that are inhaited as aerosols)- Coxiella brunetii: no arthropod vector, presents as pneumonia. "Q fever is Queer because no rash or fever, and its causative organism can survive outside its endospore form. In in the Rickettsia genus but closely related"
Chlamydia
Elementary body (small, dense), is Enfectious and Enters cells via Endocytosis
Reticular body Replicates in cell by fission; form seen on tissue culture.
C trachomatis: reactive arthritis, conjunctivitis, nongonococcal urethritis, PID
C pneumoniae and C psittaci: cause atypical pneumonia, transmitted by aerosol. C psittaci notable for an avian reservoir.
Lab dx: cytoplasmic inclusion seen on Giemsa or fluorescent AB stained smear.
Chylamidial cell wall unusual in that it lacks muramic acid
Treatment: azithro or doxy
C trachomatis serotypes
Types ABC: chronic infection, blindness due to follicular conjunctivitis in Africa “ABC=Africa/Blindness/Chronic infection).
Type D-K: urethritis, PID, ectopic pregn, neonatal pneumo, or neontal conjunctivitis. D-K everything else, Neonatal disease can br acquired during passage through infected birth canal
Type L1,2,3: lymphogranuloma venereum: painful lymph node.
Mycoplasma pneumonia
Atypical walking pneumonia: insidious onset, headache, nonproductive cough, diffuse interstitial infiltrate.
Xray looks worse than pts. High IgM, cold agglutinins, which agglutinate or lyse RBS
Grow on Eaton's agar No cell wall, not seen in Gram stain Contains sterol for stability More common in younger pts <30 yrs Frequent outbreaks in military recruits and prison
Treat with macrolide or fluoroquinolon.
Gardnerella vaginalis
Pleomorphic gram variable rods that cause vaginosis presenting as gray vaginal discharge with a fishy smell
Associated with sexual activity but no STD
Clue cells, or vaginal epithelial cells covered with bacteria
Treat with metronidazole
“I dont have a clue why I smell fish in the vagina garden”
