Meropenem for all?Midge Asogan
ICU Fellow(also ID AT)
Infections
• Common reason for presentation to ICU
• Community acquired - vs nosocomial - new infection acquired within hospital environment
• Treatment based on supportive therapy + antimicrobial therapy
• Multiple re-definitions of “Sepsis” to guide clinicians on severity of infection and predict mortality risk
Sepsis-3 Definitions
• Sepsis = life threatening organ dysfunction related to dysregulated response to infection
• Septic shock = subset of sepsis with circulatory or cellular dysfunction with higher predicted mortality
What to give?
• Choice of antimicrobials - determined by clinical scenario and most likely infecting pathogen
• Modification based on local anti-biogram
• eg multiple hospital admission + colonisation with resistant organisms warrants broader cover to account for this
Some Gram Stains!
Gram positive Cocci -clusters
• Staph aureus - MSSA or MRSA
• Still caries 20% mortality despite therapy
• Guidelines on duration of therapy; minimum 2 weeks of intravenous therapy +/- longer if deep seated infection
• Bone/joint = 4 weeks; Prosthetic material or endocarditis = 6 weeks IV; PO follow on may be required
• Staph aureus is never a contaminant unless determined by ID physician
• Better outcomes if infectious diseases specialist input for management
• Coagulase negative staph
• Staph lugdenensis - can behave like Staph aureus
• Staph epidermidis/Staph capitis/ Staph hominis
• Skin commensals - common contaminants of blood cultures
• Pathogenic in setting of prosthetic material or intravascular devices - especially if multiple positive cultures
• Usually methicillin resistant organism - Vancomycin
Gram positive cocci -chains
• Streptococci and enterococci
• Multitude of clinical entities
• Strep pyogenes (Group A Strep) - skin and soft tissue
• Associated with toxic shock
• Strep pneumoniae
• Beware invasive disease in hyposplenism, immunocompromised (HIV, multiple myeloma), extremes of age
• Viridans strep
• Agent of infective endocarditis - usually subacute
• Enterococci
Gram negative rods
• Enteric organisms - usually originate from below the diaphragm
• Biliary tree infections - cholangitis
• Intra-abdominal pathology
• Urosepsis
• Higher mortality associated with resistant gram negatives
• Driven by lack of available antibiotic therapy + increased likelihood of not receiving appropriate antibiotic therapy
• CRE infection carries 26-44% mortality (2014 meta-analysis)
Falagas ME, Giannoula ST et al, Deaths Attributable to Carbapenem-ResistantEnterobacteriaceae Infections. Emerg Infect Dis 2014 Jul : 20(7) 1170-1175
Gram positive rods
• Not always a contaminant
• Can be skin flora contaminant eg corynebacterium species, bacillus species
• Bacillus cereus - sepsis in IVDU, agent of gastroenteritis
• Branching GPR + modified Acid-fast positive = nocardia
Gram negative cocci
• Neisseria species
• Meningococcus
• Gonococcus
• Haemophilus influenzae, H parainfluenza
Nosocomial Risks• ICU population at relative risk of nosocomial infection due to
use of invasive support devices and relative immunosuppression - more likely to have chronic illness
• Increased rates of resistant organisms
• Higher micro-organism selection pressure due to use of broad spectrum antibiotics
• More difficult to treat
• Associated with increased length of stay and higher morbidity and mortality
Catheter associated UTI
• Colonisation common
• Not always associated with severe infection
• Can be managed with IDC change if no associated signs or symptoms of infection
• Asymptomatic bacteruria common - does not warrant antimicrobial therapy
Ventilator Associated Pneumonia
• Increased risk of development beyond 48h of invasive ventilation
• Increased risk of multi-drug resistant organisms if admitted to ICU for more than seven days
• Broader spectrum therapy may be warranted
Central line associated blood stream infections
• Increased risk with prolonged duration of hospital admission
• Chronic illness
• Use of parenteral nutrition
• Neutropenia/ bone marrow transplant
• Severe burns
• Coagulase negative staph
• Staph aureus
• Candida species
• Gram negative bacilli
C difficile• Broad spectrum antibiotics
• Increased risk with PPI use
• Up to 20% mortality associated with severe infection
• Mild: PO metronidazole
• Severe: PO vancomycin + IV metronidazole +/- PR vancomycin
• Surgery
• Faecal microbiota transplant