Infections on the CCFP exam

Approach

• Culture only when the result will change care. Every wound carries germs, so do not culture one with no redness, pus or growing pain.
• Infected ulcer: send deep tissue, taken by biopsy or scraping after cleaning or debridement (removing dead tissue). A surface swab gives false results both ways.
• Child in diapers: take urine by catheter or a needle above the pubic bone. A bag sample often grows skin germs. A negative bag rules infection out; a positive needs a proper sample.
• Sore throat in a child with a runny nose, cough, mouth ulcers or a hoarse voice: no strep test. Many children carry strep without being ill.
• Adults: no urine culture without urinary symptoms or fever. The exceptions are pregnancy and a urinary procedure expected to cause bleeding.
• C. difficile (a gut germ that causes diarrhea): test liquid stool only. A repeat test within 7 days rarely helps. No test of cure, and no routine test under age 1.

Approach

• Colds and flu-like illness are viral: no antibiotic. Sinus symptoms under 7 days get none either. Bacterial sinusitis usually shows only after 7 days.
• Adults with bronchitis or asthma, and children with bronchiolitis, get no antibiotic.
• Sore throat: about 10% in adults and 25% in children are bacterial. Treat only with an intermediate or high Centor or FeverPAIN score (sore-throat checklists) and a positive strep test.
• Ear infection: treat the pain first. A healthy child over 6 months with mild illness can be watched for 48 to 72 hours.
• Consider an antibiotic if a watched child is no better, or for an ear infection under 24 months in both ears, or with ear discharge.
• A mild past penicillin reaction is no reason for a second-line drug, which may work less well. Take the full story; a beta-lactam (penicillins, cephalosporins) is often safe.
• If the patient can swallow and absorb, give the oral form of a well-absorbed drug. A drip adds line risks.

Approach

• Dental abscess with fever, swollen glands, a swollen face or weak immunity: a beta-lactam for 5 days. Azithromycin or cefuroxime if allergic to penicillin.
• A simple bladder infection can be treated on the history alone, with no urine test.
• Many preschool children with pneumonia need no antibiotic: the illness is often viral.
• Child with pneumonia well enough for home: amoxicillin. Save third-generation cephalosporins (broad drugs such as ceftriaxone) for severe illness, a child without vaccines, or an area with high penicillin resistance.
• A child in hospital with pneumonia: ampicillin or penicillin G.

Approach

• New confusion in an older adult: look for infection in the chest, skin, wounds and belly. Check drugs, dehydration, constipation and pain too.
• Do not test the urine without urinary symptoms, fever or other clear signs. Without a catheter, confusion is not a symptom of a bladder infection.
• Treating bacteria found by chance does not help. It adds diarrhea, C. difficile and resistance, and the real cause gets missed.
• Pain far worse than the skin looks: think of necrotizing fasciitis, a fast, deep tissue infection that needs surgery.
• A child with fever, fast breathing and belly pain may have pneumonia low in the lung. Listen to the chest.

Approach

• Treat a return visit as new information. Take the history and examine again; do not assume the infection is just slow.
• Think of what a simple infection can hide: an abscess, bone or joint infection, a resistant germ, or the wrong diagnosis.
• A foot ulcer failing antibiotics may reach bone. Send deep tissue, not a surface swab, to choose the next drug.
• In a known bone infection, repeat imaging only if the patient is not improving, is worse, or may have an undrained abscess. Scans lag behind recovery.
• A child's uncomplicated bone infection needs no long drip.
• In a child, consider switching to oral once fever has been gone 48 to 72 hours. Markers should be normal or C-reactive protein halved, with no complications and any positive blood culture now negative.
• A diagnosis that no longer fits is the clue. An infant admitted with gastro whose diarrhea has stopped, but whose fever and drowsiness are rising, needs a new diagnosis.

Approach

• Drain a skin abscess. After draining a simple one, give no antibiotic. The exceptions: wide skin infection around it (cellulitis), red streaks up the limb, weak immunity, or illness through the whole body.
• A localized dental abscess needs dental care. Antibiotics do not ease its pain or swelling.
• Any wound: check tetanus doses and the date of the last one, then follow the table.
• Tetanus immune globulin gives quick, short cover. It is for an unknown history or fewer than 3 doses, with a wound that is not clean and minor.
• With weak antibody defences, give it for a clean, minor wound too.
• A minor illness, with or without fever, is no reason to delay the vaccine. Wait only for a severe acute illness.