Meropenem for all? Midge Asogan ICU Fellow (also ID AT)

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 metaanalysis) Falagas ME, Giannoula ST et al, Deaths Attributable to Carbapenem-Resistant Enterobacteriaceae 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