Table 1.

TIDOS Criteria for Infectious Disease Syndromes¹

ID Classification	Diagnostic Criteria
Colonization	The presence of microorganisms on skin, mucous membranes, open wounds, or in excretions or secretions but without clinical signs or symptoms compatible with an infectious disease diagnosis.
Systemic inflammatory response syndrome (SIRS)35	Patient has ≥ 2 of the following [Temp > 38°C or Temp < 36°C, HR > 90 beats/min, RR > 20 breaths/min, PaCO2 < 32 mmHg, WBC > 12000 cells/mm3, WBC < 4000 cells/mm3, WBC < 10% immature (band forms)]
Clinical sepsis	Sepsis35 - SIRS plus ≥ 1 of the following: positive culture, Gram stain of sterile body fluid, or visual evidence of infection Septic Shock36 - sepsis criteria plus ≥ 1 of the following: systemic mean BP <60 mmHg (<80 if previous hypertension) after 20–30 mL/kg starch or 40–60 mL/kg serum saline solution, PCWP 12–20 mmHg, need for dopamine at >5 mcg/kg/min to maintain BP >60 mmHg, or need for norepinephrine or epinephrine at <0.25 mcg/kg/min to maintain BP >60 mmHg
Bloodstream infection (BSI)	Recognized pathogen cultured from ≥ 1 blood cultures or patient has ≥ 2 of the SIRS criteria and ≥ 1 of the following: 1) common skin contaminant cultured from ≥ 2 blood cultures drawn on separate occasions or 2) common skin contaminant cultured from ≥ 1 blood culture from a patient with an intravascular line and physician instituted antimicrobial therapy
Osteomyelitis	Definite: Positive bone culture or evidence on direct examination of bone during surgical procedure or histopathology exam Probable: Patient has ≥ 2 signs/symptoms from group A [temp > 38°C, localized swelling, localized tenderness, localized heat, drainage] and at least one from group B [organisms cultured from blood or radiographic evidence of infection] Possible: Patient meets all criteria in Group A [open fracture or exposed bone with environmental contamination at time of injury, deep wound tissue growing any organism, evidence of local inflammation (purulence or necrotic tissue) or systemic inflammation (fever, leukocytes ≥ 12000/µL, elevated C-reactive protein or elevated erythrocyte sedimentation rate) or all criteria in Group B [non-union fracture on follow-up, Evidence of systemic inflammation (fever, leukocytes ≥ 12000/µL, elevated C-reactive protein or elevated erythrocyte sedimentation rate)]
Joint/bursa infection	Definite: organisms cultured from joint fluid/synovial biopsy or evidence of joint/bursa infection seen during a surgical operation or histopathology Possible: Patient has ≥ 2 signs/symptoms from group A [joint pain, swelling, tenderness, erythema, heat, evidence of effusion or limitation of motion] and at least one from group B [organisms and WBC seen on Gram stain of joint fluid, WBC ≥ 12000/µL in joint fluid with no other underlying rheumatologic disorder, or radiographic evidence of infection]
Disc space infection	Definite: positive culture from vertebral disc space tissue obtained during surgery or needle aspiration or evidence seen during surgical procedure or histopathology Possible: radiographic evidence and ≥ 1 of the following: fever without other recognized cause or pain at involved vertebral disc space
Wound/surgical site infections/skin & soft tissue infections (SSTI)	Superficial: Involves only skin/subcutaneous tissue and ≥ 1 of the following from each area: 1) Pain/tenderness, localized swelling, redness, or heat AND 2) purulent site drainage, organisms isolated from aspirate/aseptically obtained culture of fluid/tissue, organisms isolated from purulent drainage, or visual evidence of superficial incisional SSI or SSTI Deep: ≥ 1 of the following: purulent site drainage, organisms isolated from aspirate/aseptically obtained culture of fluid/tissue, organisms isolated from purulent drainage, deep wound/incision spontaneously dehisces or is deliberately opened by a surgeon in the presence of fever or localized tenderness, unless the wound culture is negative, abscess or other evidence of infection
Central nervous system infection	Intracranial infection: [brain abscess, subdural or epidural infection, encephalitis] or [positive culture from brain tissue or dura] or [abscess/evidence of intracranial infection seen during surgical procedure or histopathology] or [patient has at least one of the following from each group: (headache, dizziness, fever, localizing neurological signs, or change in level of consciousness or confusion) or (organisms seen on microscopy of brain/abscess tissue obtained by needle aspiration/biopsy or radiographic evidence of infection)] Meningitis or ventriculitis: Positive CSF culture or ≥ 1 of the following from each area: (fever, headache, stiff neck, meningeal signs, cranial nerve signs, or irritability) and (increased white cells, elevated protein, and/or decreased glucose in CSF, positive CSF Gram stain, positive blood culture, positive CSF, blood, or urine antigen test) Spinal abscess without meningitis: positive culture from abscess in the spinal epidural/subdural space or abscess in the spinal epidural/subdural space seen during surgery or ≥ 1 of the following from each area: (fever, back pain, focal tenderness, radiculitis, paraparesis, or paraplegia) and (positive blood culture or radiographic evidence)
Intrathoracic/pulmonary infection	Pneumonia: both must be present – (New or progressive infiltrate seen on radiology film and evidence of infection (temp >38°C or <36°C or WBC ≥12000 or <4000)) and (new onset purulent sputum, change in character of sputum, increase respiratory secretions, new onset worsening cough, dyspnea, or tachypnea, rales/bronchial breath sounds, worsening gas exchange, same organism growing from respiratory secretions as found in blood cultures, positive culture from minimally contaminated lower respiratory tract specimen, ≥5% BAL-obtained cells contain intracellular bacteria on direct microscopy, or laboratory evidence of uncommon pathogen) Empyema: ≥ 1 of the following: positive culture from pleural fluid biochemical analysis consistent with empyema, empyema seen during surgery or histopathology, or radiographic evidence consistent with empyema Lung abscess: ≥ 1 of the following: organism seen on smear or cultured from lung tissue or fluid, including pleural fluid, lung abscess seen during a surgical operation or histopathology, or abscess cavity seen on radiographic examination of lung
Intraabdominal infection	Includes gall bladder, bile ducts, liver, spleen, pancreas, peritoneum, subphrenic or subdiaphragmatic space, or other intra-abdominal tissue or area not otherwise specified; positive culture of purulent material from intra-abdominal space obtained during surgery/needle aspiration or abscess or other evidence of intra-abdominal infection seen during surgery/histopathology exam or ≥ 2 of the following: temp >38°C, nausea, vomiting, abdominal pain, jaundice, or paraparesis plus or ≥ 1 of the following: organisms cultured from drainage from surgically placed drain, organisms seen on Gram stain of drainage/tissue obtained during surgery or needle aspiration, or radiographic evidence of infection

¹Diagnostic criteria derived from standardized definitions for nosocomial infections used by the National Healthcare Safety Network (NHSN).¹⁷