Transmission and effect of multiple clusters of seasonal influenza in a Swiss geriatric hospital

Objectives

To investigate a nosocomial outbreak of influenza.

Design

Prospective outbreak investigation with active case finding and molecular typing.

Setting

A large academic geriatric hospital in Switzerland.

Participants

Elderly hospitalized adults.

Measurements

Based on syndromic surveillance, a nosocomial influenza outbreak was suspected in February 2012. All suspected cases were screened for respiratory viruses using real‐time reverse transcription polymerase chain reaction of nasopharyngeal swabs. Infection control procedures (droplet precautions with single room isolation whenever possible) were implemented for all suspected or confirmed cases. Specimens positive for influenza viruses were processed and sequenced whenever possible to track transmission dynamics.

Results

Respiratory samples from 155 suspected cases were analyzed during the outbreak period, of which 69 (44%) were positive for influenza virus, 26 (17%) were positive for other respiratory viruses, and 60 (39%) were negative. Three other cases fulfilled clinical criteria for influenza infection but were not sampled, and one individual was admitted with an already positive test, resulting in a total of 73 influenza cases, of which 62 (85%) were classified as nosocomial. Five distinct clusters of nosocomial transmission were identified using viral sequencing, with epidemiologically unexpected in‐hospital transmission dynamics. Seven of 23 patients who experienced influenza complications died. Sixteen healthcare workers experienced an influenza‐like illness (overall vaccination rate, 36%).

Conclusion

Nosocomial influenza transmission caused more secondary cases than repeated community importation during this polyclonal outbreak. Molecular tools revealed complex transmission dynamics. Low healthcare worker vaccination rates and gaps in recommended infection control procedures are likely to have contributed to nosocomial spread of influenza, which remains a potentially life‐threatening disease in elderly adults.

Participation of elderly adults in randomized controlled trials addressing antibiotic treatment of pneumonia

OBJECTIVES

To examine how relevant current evidence on antibiotic treatment of pneumonia is for elderly adults.

DESIGN

Systematic review.

SETTING

Randomized controlled trials (RCTs; N = 43) comparing different antibiotics and prospective observational studies (N = 182) published since 2005.

PARTICIPANTS

Adults with community-acquired (CAP), healthcare-associated (HCAP), hospital-acquired (HAP), or ventilator-associated (VAP) pneumonia.

MEASUREMENTS

Exclusion criteria that could preferentially limit participation of elderly adults were examined, subgroup or other adjusted analyses were searched for according to age, and treatment effects in participants younger than 65 in RCTs were compared with those in participants aged 65 and older. Mean participant ages in RCTs and observational studies were compared. Risk ratios (RRs) with 95% confidence intervals (CIs) for differences between older and younger adults were pooled using a fixed effect metaanalysis.

RESULTS

No RCT reported exclusion based on an upper age limit; 100% of community CAP trials, 90% of hospitalized CAP trials, and 76% of HAP and VAP trials excluded individuals based on comorbidities. None of the RCTs reported a subgroup analysis for mortality according to age. The RR for the pooled difference in treatment failure rates between participants younger than 65 and those aged 65 and older was 1.25 (95% CI = 0.94-1.65, 12 RCTs) and between participants younger than 75 and aged 75 and older was 1.43 (95% CI = 0.98-2.09, 7 RCTs). RCT participants were significantly younger (54.0 ± 9.6) than those in observational studies of CAP (66.2 ± 8.1, P < .001). Age differences were not significant for HCAP, HAP, and VAP.

CONCLUSION

Elderly adults are often excluded from RCTs of bacterial pneumonia. No data were found on the comparative efficacy of antibiotic treatment in elderly adults and the general population.

Augmented renal clearance, low β-lactam concentrations and clinical outcomes in the critically ill: an observational prospective cohort study

Whilst augmented renal clearance (ARC) is associated with reduced β-lactam plasma concentrations, its impact on clinical outcomes is unclear. This single-centre prospective, observational, cohort study included non-pregnant, critically ill patients aged 18-60 years with presumed severe infection treated with imipenem, meropenem, piperacillin/tazobactam or cefepime and with creatinine clearance (CL(Cr)) ≥60 mL/min. Peak, intermediate and trough levels of β-lactams were drawn on Days 1-3 and 5. Concentrations were deemed 'subthreshold' if they did not meet EUCAST-defined non-species-related breakpoints. Primary and secondary endpoints were clinical response 28 days after inclusion, and ARC prevalence (CL(Cr)≥130 mL/min) and subthreshold and undetectable concentrations, respectively. Logistic regression was used to evaluate associations between ARC, antibiotic concentrations and clinical failure. From 2010 to 2013, 100 patients were enrolled (mean age, 45 years; median CL(Cr) at inclusion, 144.1 mL/min). ARC was present in 64 (64%) of the patients. Most patients received imipenem/cilastatin (54%). Moreover, 86% and 27% of patients had at least one subthreshold or undetectable trough level, respectively. Among imipenem and piperacillin trough levels, 77% and 61% were subthreshold, respectively, but intermediate levels of both antibiotics were largely above threshold. ARC strongly predicted undetectable trough concentrations (OR=3.3, 95% CI 1.11-9.94). A link between ARC and clinical failure (18/98; 18%) was not observed. ARC and subthreshold β-lactam antibiotic concentrations were widespread but were not associated with clinical failure. Larger studies are necessary to determine whether standard dosing regimens in the presence of ARC impact negatively on clinical outcome and antibiotic resistance.

General issues on microbial translocation in HIV-infected patients

The lumen of the gastrointestinal tract is home to an enormous quantity of different bacterial species that thrive in an often symbiotic relationship with the host. It is the principal source of microbial products because of its massive bacterial load. Injury to the immune component of the gastrointestinal mucosal surface, along with damage to the intestinal epithelial microenvironment with its antimicrobial functions, may affect systemic immune activation during the chronic phase of HIV infection through the increased translocation of luminal microbial products. Moreover, microbial translocation, which is defined as "the passage of both viable and nonviable microbes and microbial products such as endotoxin across anatomically intact intestinal barrier", may be a fundamental mechanism through which HIV accelerates progression of chronic viral hepatitis. Improvements in the tools available to microbiota research, and especially advancement of our knowledge in this area may help us in controlling the evolution of HIV disease, although population complexity and diversity between individuals make this challenging.

Strategies and challenges of antimicrobial stewardship in long-term care facilities

As people are living longer the demand for long-term care facilities (LTCFs) continues to rise. For many reasons, antimicrobials are used intensively in LTCFs, with up to a half of this use considered inappropriate or unnecessary. Over-use of antimicrobials can have direct adverse consequences for LTCF residents and promotes the development and spread of resistant bacteria. It is therefore critical that LTCFs are able to engage in antimicrobial stewardship programmes, which have the potential to minimize the antibiotic selective pressure, while improving the quality of care received by LTCF residents. To date, no antimicrobial stewardship guidelines specific to LTCF settings have been published. Here we outline the scale of antimicrobial use in LTCFs and the underlying drivers for antibiotic over-use. We further describe the particular challenges of antimicrobial stewardship in LTCFs, and review the interventional studies that have aimed to improve antibiotic use in these settings. Practical recommendations are then drawn from this research to help guide the development and implementation of antimicrobial stewardship programmes.

Optimizing antimicrobial therapy in critically ill patients

Critically ill patients with infection in the intensive care unit (ICU) would certainly benefit from timely bacterial identification and effective antimicrobial treatment. Diagnostic techniques have clearly improved in the last years and allow earlier identification of bacterial strains in some cases, but these techniques are still quite expensive and not readily available in all institutions. Moreover, the ever increasing rates of resistance to antimicrobials, especially in Gram-negative pathogens, are threatening the outcome for such patients because of the lack of effective medical treatment; ICU physicians are therefore resorting to combination therapies to overcome resistance, with the direct consequence of promoting further resistance. A more appropriate use of available antimicrobials in the ICU should be pursued, and adjustments in doses and dosing through pharmacokinetics and pharmacodynamics have recently shown promising results in improving outcomes and reducing antimicrobial resistance. The aim of multidisciplinary antimicrobial stewardship programs is to improve antimicrobial prescription, and in this review we analyze the available experiences of such programs carried out in ICUs, with emphasis on results, challenges, and pitfalls. Any effective intervention aimed at improving antibiotic usage in ICUs must be brought about at the present time; otherwise, we will face the challenge of intractable infections in critically ill patients in the near future.

Aminoglycosides use in patients over 75 years old

OBJECTIVE

to describe aminoglycoside use and nephrotoxicity in patients older than 75 years.

DESIGN

retrospective multicenter study.

SETTING

hospital department, rehabilitation, long-term care center.

POPULATION

patients ≥75 years old treated by aminoglycosides.

RESULTS

184 patients, mean age: 84.4 years (range: 75-101). One hundred and twenty-seven patients received other nephrotoxic drug(s). Gentamicin (70%) and amikacin (30%) were used and the once-daily dosing was preferred (92%). Average treatment period was 2.75 (1-10) days for amikacin and 4.4 (1-30) for gentamicin with average dosage 13.5 and 3.5 mg/kg/day, respectively. The monitoring of maximal plasmatic concentration (Cmax) was done in 37 patients, 9 of them had probabilistic treatment. Only one had a Cmax fulfilling the objective of French recommendations (gentamicin >30 mg/l, amikacin >60 mg/l). When infection was documented, the objective of Cmax >10 × minimal inhibitory concentration of the strain was reached for 27%. Minimal plasmatic concentration was checked in 38% of cases, with adequate value (gentamicin <0.5 mg/l, amikacin <2.5 mg/l) for 37%. At the end of aminoglycoside course, 40 patients increased their serum creatinine >25% of the baseline value. In multivariate analysis, this was associated with treatment length ≥3 days and concomitant use of nephrotoxic drugs.

CONCLUSION

aminoglycosides dosing used in elderly patients probably need therapeutic drug monitoring and dose adjustment. Aminoglycosides are used to treat severe infections. One of the most important side effects is nephrotoxicity in oldest patients. To minimise nephrotoxicity, short treatments are necessary and avoiding others nephrotoxic drugs could be relevant.

Is there any benefit in pre-operative urinary analysis before elective total joint replacement?

Whether patients with asymptomatic bacteriuria should be investigated and treated before elective hip and knee replacement is controversial, although it is a widespread practice. We conducted a prospective observational cohort study with urine analyses before surgery and three days post-operatively. Patients with symptomatic urinary infections or an indwelling catheter were excluded. Post-discharge surveillance included questionnaires to patients and general practitioners at three months. Among 510 patients (309 women and 201 men), with a median age of 69 years (16 to 97) undergoing lower limb joint replacements (290 hips and 220 knees), 182 (36%) had pre-operative asymptomatic bacteriuria, mostly due to Escherichia coli, and 181 (35%) had white cells in the urine. Most patients (95%) received a single intravenous peri-operative dose (1.5 g) of cefuroxime as prophylaxis. On the third post-operative day urinary analysis identified white cells in 99 samples (19%) and bacteriuria in 208 (41%). Pathogens in the cultures on the third post-operative day were different from those in the pre-operative samples in 260 patients (51%). Only 25 patients (5%) developed a symptomatic urinary infection during their stay or in a subsequent three-month follow-up period, and two thirds of organisms identified were unrelated to those found during the admission. All symptomatic infections were successfully treated with oral antibiotics with no perceived effect on the joint replacement.

We conclude that testing and treating asymptomatic urinary tract colonisation before joint replacement is unnecessary.

Cite this article: Bone Joint J 2014;96-B:390–4.

Ceftaroline for the treatment of prosthetic valve endocarditis due to methicillin-resistant Staphylococcus aureus

The case is described of a frail patient who developed prosthetic valve endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA). Conventional antimicrobial treatments either failed or were contraindicated, and the patient was judged unsuitable for a further valve replacement. A salvage therapy with high doses of a new cephalosporin, ceftaroline, given three times daily was undertaken; subsequently, the patient had not relapsed at two months after completing a six-week course of ceftaroline. Ceftaroline deserves major attention as an alternative choice in difficult-to-treat MRSA endocarditis.