ID

Diplococci

Gram (-) Diplococci

Gram (-) Coccobacillus

Coccobacillus

Gram (-) Rods

Rods

Gram (+) Cocci

Hemolysis

(-)

Catalase

(+)

Cocci

Rods

Gram (+) Rods

Atypical Gram (+)

Atypicals

Mycoplasma pneumoniae

Chlaymdia

pneumoniae

Legionella

pneumophila

Obligate Aerobe:

• Requires O2: "Nagging Pest Must Breathe"
• Nocarida, Pseudomonas, Mycoplasma tubercolosis, Bordetella and Bacillus

Obligate ANAerobe:

• No O2 (gut and mouth) : "Can't Breathe Pure Fresh Air"
• Clostridium, Bacteriodes fragilis, Peptostreptococcus, Fusobacterium, Actinmyces bovis

Facultative Anaerobe:

• Can use O2, but not required
• Streptococci, Staphlococci, gram (-)

Gram Stains

Positive (purple): Thick peptidoglycan, Holds crystal violet

Negative (red/pink): Thin peptidogylcan, Decolorizes then holds safran

STEPS:

1. Fixation

2. Crystal Violet

3. Iodine: Makes all cells purple

4. Decolorization: Only gram positive bacteria will keep purple color

5. Safranin

a. Gram positive will stay purple

b. Gram negative will become red/pink from safranin

Limitations: Not good for mycobacteria or Nocardia (Acid fast), Mycoplasma (PCR), Chlamydia (NAAT), Rickettsia (Titer), Treponema (Microscopy)

Should NOT get epithelium cells

High WBC's indicate infection

Other types of Bacterial Stains

Silver

• Only useful for 3 infections:

1. Pneumocystis PNA (HIV/AIDS)

2. Legionella

3. H. Pylori

India Ink

• Fungi and yeast
• Negative stain (colors background)

Giemsa

• Stains nucleic acids (intracellular)
• Used for blood smears and marrow
• Protozoa: Plasmodium, Trypanosomes
• Intracellular: Chlamydia, Rickettsia, Borrelia

Ziehl-Neelsen: “acid-fast”

• Mycobacterium, mycolic acids and lipids
• Nocardia

Streptococcus

pneumoniae

Neisseria

meningitidis

Haemophilus

influenzae

Streptococcus

agalactiae

Listeria

monocytogenes

Streptococcus

pneumoniae

H. influenzae

M. pneumoniae

S. aureus

C. pneumoniae

L. pneumonphila

S. pneumoniae

P. acnes

S. aureus

S. pyrogens

S. epidermitis

Enterococcus

S. viridans

Actinomyces

Streptococcus

pneumonia

Haemophilus

Influenzae

Moraxella catarrhalis

Streptococcus

pyrogens

Kingella

kingae

S. aureus

N. gonorrhoeae

C. trachomatis

Intial infection w/u:

1. S&S

2. Gram stain w/ culture

3. CBC w/ diff

4. CRP, ESR

5. Antibody testing

6. Spcial stains

7. DNA probes, PCR, EIA

ADME Review:

• First pass: a phenomenon of drug metabolism whereby the concentration of the drug is greatly reduced before it reaches systemic circulation. Systems that affect first pass: GI lumen, gut wall, bacterial, hepatic enzymes
• Bioavailability: the fraction of an administered dose of unchanged drug that reaches the systemic circulation
• Parental: anything besides GI, so IM, IV, SubQ
• Enteral: intestinal administration (oral, sublingual, rectal)
• Bactericidal: kill bacteria by breaking cell wall
• Bacteriostatic: inhibit growth, will not kill alone. Still relies on the immune system
• Broad spectrum: kill everything (i.e., gram -, gram +, and anaerobes), will also eliminate normal flora; increase resistance
• Narrow spectrum: Specific target (i.e., only gram +)
• Therapeutic index: how much drug you can give to be effective at combating disease and not cause harmful effects
• Concentration dependent: rate and extent of effectiveness increases as the drug concentration increases
• Time-dependent: drug is still effective as long as minimum bactericidal concentration is maintained.
• Associated with cell wall synthesis inhibitors
• BBB:
• Decreased permeability to water-soluble or ionized molecules
• Lipid soluble diffuse easily and rapidly
• 1st gen cephalosporins do not penetrate BBB

Resistance

Mechanisms of Resistance:

• Bacteria employ one or more of the following mechanisms
• Enzymatic degradation of the antibiotic agent
• Alterations of the targets of the antibiotic agents
• Changes in the call wall permeability
• Production of efflux pumps

Antiograms help guide therapy and reduce resistance potential

UNMH Antibiogram

Beta-

Lactams

Peptide

Inhibitors

Aminoglycosides

(narrow)

Tetracyclines

Macrolides

Lincosamides

Fluoroquinolones

Metronidazole

Metabolite inhibitors

Pathogens

• Bacterial: Staph, Strep, Pseudo, E. Coli, Atyplical
• Fungal:Candida, Aspergillus

Systemic infections can spread to eye and lead to Choroidits if left untreated

Stye/Hordeolum

• Impacted eyelash follicle
• Warm compress
• Abx not needed

Chalazion

• Impacted gland on back of eyelid
• MC is staph
• Abx may be needed
• Referral to ophthalmology, +/- drain

Conjunctivitis "pink eye"

• Usually viral (Adenovirus)
• S&S= rhinnitus, bilateral injection, coughing
• No URI sx and unilateral, think bacterial
• P/w: water eyes, redness, burning
• Sx peak 5-7 days, can spread to other eye
• If doesn't resolve in 3-4 weeks in adults, think chamydia
• Complications: epidermitic keratoconjunctivitis
• corneal inflitrates, refer: needs steroids

Neonatal Conjunctivitis:

-All neonates are treated with erythromycin ointment

Bacterial Keratitis

• Corneal abrasion 2/2 contact lens use overnight
• P/w: redness with blurred vision, photophobia
• Can lead to corneal ulceration, emergent!
• Pseudo is most concerning, Staph/Strep also common
• Abx: Tobromycin + vancomycin hourly

Ocular Trachoma

• Not common in US
• Leading cause of preventable blindness worldwide
• 2/2 chronic conjunctivitis and repeated scarring
• Preventative Trt: need to prevent repeated infections
• Once blindness occurs, no treatment available

Herpes Keratitis

• Dendritic lesions on exam
• MC is HSV
• P/w: redness, +/- unilateral, +/- skin findings
• Trt: Emergent referral to ophthalmology, need steroid drops
• Complications: can produce scar and affect vision, often recurs

Preseptal Cellulitis

• Scratch and infection on peri-ocular skin
• Swollen, erythematous eyelid, EOM is painful
• Staph/strep MC
• Dx: with CAT scan
• Trt: oral cephalexin

Dacryocystitis !!!

• Inflammation of lacrimal sac
• 2/2 obstruction
• Trt: refer, oral ABX, I&D, surgery

Orbital Cellulitis !!!

• Infection of connective tissue posterior to obtial spetum
• 2/2 complication from ethmoid sinusitis, dental infection
• Strep/Staph/ H. influenza are MC
• P/w: erythema, pain, proptosis, reduced EOM, double vision
• Trt: oral ABX, ENT will drain
• Complications: blindness, bacteremia

Endophthalmitis

• Infection inside eyeball
• 2/2 surgery, trauma, renal failure
• Endogenous or exogenous
• P/w: red, painful, Hypopion (white blood cell pooling)
• Trt: Refer, vitrectomy with oral ABX
• Poor prognosis

Otitis Media

• MC in kids 2/2 eustachian tube anatomy
• Viral or allergy mediated
• P/w: fever, ear pain, ear pulling
• Dx: TM's red and bulging, weber test with tuning fork
• Trt: usually none, or AMOX

SEROUS OM:

• Viral
• TM's dull, injected, and retracted

Mastoiditis

• Complication of otitis media to mastoid cells of temporal bone
• Can cause osteomyelitis or brain abscess
• Trt with abx

Otitis externa

• Infection of the external ear canal
• Swimmer's ear:
• Pseudo, green discharge
• Trt: ciprofloxacin drops

• Aspergillus:
• Black specked debris (fungal)

Sinusitis

• Infection of the sinuses
• Viral: MC and 2/2 rhinovirus, RSV, adenovirus, influenza
• Bacterial: usually after viral infection, normal flora overgrow and cause disease
• P/w: double sickening
• Dx: Red boggy turbinates, obstructed sinuses, CRP
• Trt: Do not treat
• Persists: consider AMOX

See learn article for more info

Pharyngitis

• Viral in adults (MC)
• GAS in kids
• Arcanobacterium also possible
• Trt: PEN or AMOX

Tonsillitis/Peritonsillar Abcess !!!

• GAS or Arcanobacterium
• P/w: unilateral enlargement, displaces uvula, drooling , muffled voice
• Trt: I&D at ED and PEN or AMOX, prednisone

EPiglottis !!!

• Infection of the epiglottis
• P/w: stridor, drooling, dysphagia, relief when sitting forward
• DX: thumb sign on XR
• Trt: Emergent ED transport 2/2 airway obstruction

Retropharnygeal Abscess !!!

• GAS is MC
• P/w: stridor, drooling, dysphagia, trismus
• Trt: Emergent transport to ED, can obstruct airway

IV abx and I&D

Ludwig's Angina !!!

• Infection of submandibular space
• 2/2 dental infection or mouth injury
• HIV association
• P/w: cellulitis w/o lympadenopathy, fever, pain, stiff neck, drooling
• Dx: woody indurated area, redness on floor of mouth that is TTP, CT for edema
• Trt: Emergent transport to ED, can obstruct airway

IV AMP/SUL and I&D

Folliculitis

Organisms:

Staph. aureus, Pseudomonas aeruginosa (hot tub folliculitis)

P/w:

Singular or clusters of small papules/pustules with erythema

Trt:

Topical Mupirocin, Clindamycin or Erythromycin

Impetigo

Organisms:

S. aureus, S. pyogenes

P/w:

Superficial, intra-epidermal vesicles, "honey crust"

Trt:

Topical Mupirocin TID x 10 days

Erysipelas

Organisms:

-Strep. pyrogens

P/w:

- Well-demarcated, edema, warmth, tenderness, MC on the face

-Spread through lymphatics

Trt:

Penicillin or Clindamycin (w/ Hx of PCN allergy)

Cellulitis

Organisms:

- Staph. aureas, Strep pyrogens

P/w:

- poorly demarcated, erythema, edema, warmth, tenderness, indurated

Trt:

Cephalexin or Clindamycin (w/ Hx of PCN allergy)

Necrotizing fasciitis

Organisms:

- Strep pyrogenes, Staph aureus, Clostridium, enteric bacteria, polymicrobial

P/w:

Pain out of proportion (early on, no pain = late finding), edema, skin necrosis, bullae, cutaneous numbness, fever, crepitus

Trt:

Surgical debridement + broad spectrum antibiotics

Broad Spectrum = Ampicillin/sulbactam, Piperacillin/tazobactam, Imipenem

Abscesses

Organisms:

Staph. aureus, Anaerobes (pilonidal)

P/w:

Erythema, edema, warmth, tenderness and fluctuance

Trt:

I&D w/ culture, abscess >5cm in diameter need to be packed

TMP-SMX (Trimethorpim-Sulfamethoxazole)

Hematogenous Osteomyelitis

Organisms: S. aureus, Strep. pyogenes, Salmonella (sickle cell), Myobacterium, S. epidermidis (ORIF), Haemophilus influenzae (unvaccinated peds)

RF: ORIF, unvaccinated, immunocompromised, IVDA

P/w: fever, chills, fatigue, pain with affected bone, erythema, swelling

Trt: IV Vancomycin (cover MSSA/MRSA/GAS

Non-Hematogenous Osteomyelitis

Local Infection(usually polymicrobial): S. aureus, G - Bacilli, Anaerobes

Puncture wound: S. aureus, GAS, Pseudomonas aeruginosa

RF: DM, decubitus ulcer, mastoiditis/sinusitis

P/w: swelling, erythema, warmth, fever, chills, chronic ulcer

Trt: IV Vancomycin, PO Ciprofloxacin for Pseudomonas coverage

Septic Arthritis

Organisms: S. aureus, GAS, Neisseria gonorrheae, Salmonella (sickle cell), Rubella, Parvo, Hep B

RF: Peds <3 y/o (MC post GAS infection), untreated STI, IVDA, sickle cell

P/w: Monoarthritic joint (MC in lower extremities), fever, chills, erythema, decreased ROM, STI GU symptoms

Trt: Non-gonococcal IV Vancomycin, Gonococcal IV or PO Ceftriaxone

Spinal Epidural Abscess

Organisms: S. aureus, E. coli, S. epidermidis, P. aeruginosa, fungi

RF: IVDA, immunocompromised, ETOH abuse, recent spinal surgery, prothetic device

P/w: fever, chills, back pain, malaise, fatigue

Trt: IV Vancomycin + Metronidazole

Post-Infectious Reactive Arthritis

Organisms: GAS, Neisseria meningitis, Neisseria gonorrhea, Chlamydia trachomatis, Salmonella, Shigella, Campylobacter

RF: post bacterial or viral infection

P/w: Polyarticular involvement that commonly presents with larger joints 4-6 weeks post bacterial or viral infection

Trt: Predninsone to decrease inflammation

Sepsis

P/w:

Labs:

Morbidity/Mortality:

SIRS

P/w:

Labs:

Morbidity/Mortality:

Bacteremia

RF:

Continous v. intermittent:

Endocarditis

SUB-ACUTE

RHEUMATIC

ACUTE

RF:

Organisms:

P/w:

Dx:

Trt:

Myocarditis

RF:

Organisms:

P/w:

Dx:

Trt:

Pericarditis

RF:

Organisms:

P/w:

Dx:

Trt:

Bacterial meningitis

RF:

Organisms:

-Neonates:

-Kids:

-Adolescents:

-Adults:

-Elderly:

P/w:

Dx:

Trt:

-Neonates:

-Kids:

-Adolescents:

-Adults:

-Elderly:

-Complications:

Aseptic meningitis

RF:

Organisms:

P/w:

Dx:

Trt:

Complications:

Encephalitis

RF:

Organisms:

P/w:

Dx:

Trt:

Complications:

Brain abscess

RF:

Organisms:

P/w:

Dx:

Trt:

Complications: