| Suspected site | Symptoms/signs* | Initial microbiologic evaluation¶ |
| Upper respiratory tract | Pharyngeal inflammation plus exudate ± swelling and lymphadenopathy | Throat swab for aerobic culture |
| Lower respiratory tract | Productive cough, pleuritic chest pain, consolidative auscultatory findings | Sputum of good quality, rapid influenza testing, urinary antigen testing (eg, pneumococcus, legionella; not recommended in children), quantitative culture of protected brush or bronchoalveolar lavage |
| Urinary tract | Urgency, dysuria, loin, or back pain | Urine culture and microscopy showing pyuria |
| Vascular catheters: arterial, central venous | Redness or drainage at insertion site | Culture of blood (from the catheter and a peripheral site), culture catheter tip (if removed) |
| Indwelling pleural catheter | Redness or drainage at insertion site | Culture of pleural fluid (through catheter) |
| Wound or burn | Inflammation, edema, erythema, discharge of pus | Gram stain and culture of draining pus, wound culture not reliable |
| Skin/soft tissue | Erythema, edema, lymphangitis | Culture blister fluid or draining pus; role of tissue aspirates not proven |
| Central nervous system | Signs of meningeal irritation | CSF cell count, protein, glucose, Gram stain, and cultureΔ |
| Gastrointestinal | Abdominal pain, distension, diarrhea, and vomiting | Stool culture for Salmonella, Shigella, or Campylobacter; detection of Clostridium difficile toxin |
| Intra-abdominal | Specific abdominal symptoms/signs | Aerobic and anaerobic culture of percutaneously or surgically drained abdominal fluid collections |
| Peritoneal dialysis (PD) catheter | Cloudy PD fluid, abdominal pain | Cell count and culture of PD fluid |
| Genital tract | Women: Low abdominal pain, vaginal discharge Men: Dysuria, frequency, urgency, urge incontinence, cloudy urine, prostatic tenderness | Women: Endocervical and high vaginal swabs onto selective media Men: Urine Gram stain and culture |
| Bone | Pain, warmth, swelling, decreased use | Blood cultures, MRI, bone cultures at surgery or by interventional radiology |
| Joint | Pain, warmth, swelling, decreased range of motion | Arthrocentesis with cell counts, Gram stain, and culture |
