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