Penicillin-susceptible Staphylococcus aureus (SA) infection in an era of multidrug resistance

• Retrospective chart review of patients with SA in blood cultures in lab

database (period July-Dec 2011): adults only, no repeat episodes

• Study background :

– 5% of methicillin-sensitive SA isolates are sensitive to penicillin

– Aimed to characterise frequency of serious infections due to penicillin-sensitive SA

(PSSA) and how these patients are managed

• Of 445 patients with SA: 280 had MSSA

• Of 280 patients with MSSA: 58 (21%) had PSSA

• Mortality in PSSA group during index hospitalisation: 14%

• 2 excluded (no adults), 8 received broad spectrum antibiotics or died

48 patients with PSSA were analysed for treatment choice

Goodman J. IDSA 2012 abs.169

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Penicillin-susceptible Staphylococcus aureus (SA) infection in an era of multidrug resistance

Labs should (continue to) report penicillin sensitivity for SA infection because large part of MSSA is PSSA;

many patients with PSSA receive inappropriate therapy

Goodman J. IDSA 2012 abs.169

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Prevalence and risk factors of carriers of extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae

• Prospective single-centre study in 525 patients admitted to hospital

(over 1 week) and screened for ESBL

• Excluding paediatric and obstetric departments, rectal swabs

collected

• 56/525 (10.6%) were positive for ESBL:

– 41/56 (73.2%) with E. Coli

– 76.8% without positive clinical cultures or not previously known as ESBL carrier

• Multivariate analysis to identify independent risk factors for ESBL

carriage

Shitrit P. IDSA 2012 abs.1438

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Prevalence and risk factors of carriers of extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae

• Of screened patients with ≥1 risk factor (N=273), 49 (18%) was positive compared with 7/252 (3%) of screened patients without risk factors

• Screening of population at risk would discover 88% of positive pts

11% prevalence of ESBL carriers among new hospital admissions and the identification of risk factors warrant targeted screening

Shitrit P. IDSA 2012 abs.1438

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Antibiotic combination therapy vs monotherapy for Pseudomonas aeruginosa bloodstream infections

• 2-centre retrospective review of adult patients with bloodstream infections due to Pseudomonas aeruginosa (period 2006-2011) who started on antibiotic combination therapy

• Comparison between patients who continued to those who changed to monotherapy after report of antimicrobial susceptibility testing (AST)

• Of 239 patients, 148 (62%) started on combination therapy, and after AST:

Viehman JA. IDSA 2012 abs.762

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Antibiotic combination therapy vs monotherapy for Pseudomonas aeruginosa bloodstream infection

• No difference between groups in age, gender, presence of diabetes, neutropenia, septic shock, history of organ transplant mechanical ventilation, Charlson comorbidity index, rate of C. difficile colitis (±10%) and acute renal failure after antibiotics (±17%)

• Multivariable logistic regression analysis: no difference for adjusted in-hospital mortality between combi and monotherapy (39% vs 32%, P=0.19)

Continuing double coverage in pts with Pseudomonas bloodstream infection once AST data are available seems not beneficial

Viehman JA. IDSA 2012 abs.762

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Evaluation of serotonin toxicity associated with linezolid or vancomycin treatment

• Observational matched cohort study in 502 hospitalised patients treated with linezolid or vancomycin (1:1) at the Upstate New York Veterans’ Affairs Healthcare Network (period 2005-2008)

• Matching for:– Hospital– Hospital ward (ICU vs non-ICU)– Hospital length of stay prior to treatment start with linezolid/vancomycin– Age (<50, 51-75, >75 yr)– Baseline platelets (< or >100,000 cells/mm3)

• Toxicity evaluation using intensive natural word search algorithm:– Symptoms consistent with serotonin toxicity– Hunter serotonin toxicity criteria (HSTC)

Lodise T. IDSA 2012 abs.1318

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Evaluation of serotonin toxicity associated with linezolid or vancomycin treatment

• Baseline patient characteristics similar for linezolid and vancomycin groups

Low rates of serotonin toxicity are found in hospitalised patients treated with linezolid (slightly more with vancomycin)

Lodise T. IDSA 2012 abs.1318

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Emergence of oseltamivir resistance in patients with influenza A infections

• Global observational trial IRIS: Influenza Resistance Information Study (NCT00884117)

• Patients with influenza-like illness and/or positive rapid test for influenza:

– Throat/nose swabs on day 1, 3, 6, 10 for real-time RT-PCR analysis of influenza type/subtype, resistance to neuraminidase inhibitor oseltamivir

– Severity scoring (0-3) of 7 symptoms for day 1-12

• Of 1,855 RT-PCR positives with single influenza infection in first 3 yr: 1,310 patients had influenza A

• 700/1,310 (53%) received oseltamivir monotherapy within 2 days after symptom onset: N=9 with seasonal H1, N=222 with H3N2, N=469 with H1N1 2009

Schutten M. IDSA 2012 abs.94

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Emergence of oseltamivir resistance in patients with influenza A infections

• Post day 1 emergent resistance to oseltamivir in influenza A patients: 19 out of 700 patients (2.7%):

Emergent resistance of influenza A to oseltamivir seems to occur mostly in 1-5 yr old children, without effect on symptom resolution

Schutten M. IDSA 2012 abs.94

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Feedback intervention on infectious disease (ID) physicians in antibiotic stewardship programme

• Prospective single-centre study in 8 ID physicians• Restricted antibiotic prescriptions:

– Daptomycin, carbapenem, linezolid, micafungin, tigecycline, voriconazole, posaconazole

– Reviewed by an ID Pharm D– Intervention: feedback on weekly ratio to individual ID physician in relation to

anonymous colleagues

• Decreased in number of restricted prescriptions for each ID physician

Feedback intervention seems to influence ID physicians’ prescribing habits and may reduce variability

Landon E. IDSA 2012 abs.741

Voriconazole therapeutic drug monitoring in haematologic and ICU patients with invasive aspergillosis (IA)

• HPLC study of 81 voriconazole plasma concentrations (VPC) in 18 patients:

– 13 ICU patients; 5 haematologic patients– 8 with probable IA, 8 with possible IA, 2 with voriconazole prophylaxis

• With target range on 1.5-5.5 mg/l:

Hoenigl M. IDSA 2012 abs.233

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Voriconazole therapeutic drug monitoring in haematologic and ICU patients with invasive aspergillosis (IA)

• Continuously low VPC in 3 patients (despite dosage increase to

12 mg/kg) discontinuation of voriconazole change to

alternative therapy: 2 on oral posaconazole, 1 on liposomal

amphotericin B

• Toxicity: 3 patients with cholestatic hepatopathy

– VPC 6.0 mg/l

– VPC 4.2 mg/l

– VPC 1.4 mg/l despite voriconazole 12 mg/kg

Given that VPCs below target range are frequently found in haematologic and ICU patients, therapeutic drug monitoring of

voriconazole may be useful

Hoenigl M. IDSA 2012 abs.233

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