Clinical effectiveness of cefiderocol for the treatment of bloodstream infections due to carbapenem-resistant Acinetobacter baumannii during the COVID-19 era: a single center, observational study

BACKGROUND

We assessed the clinical effectiveness of cefiderocol (CFDC) in comparison with colistin (COL) for the treatment of carbapenem-resistant Acinetobacter baumannii (CRAB) bloodstream infections (BSI).

MATERIALS/METHODS

Retrospective cohort study including adults with CRAB-BSI. Outcomes were mortality, clinical cure and adverse events during therapy. The average treatment effect of CFDC compared to COL was weighted with the inverse-probability treatment weight (IPTW).

RESULTS

Overall, 104 patients were included (50 CFDC, 54 COL), median age 66.5 years, median Charlson Comorbidity Index 5, septic shock in 33.6% of patients. Primary BSI accounted for 43.3% of cases, followed by ventilator-associated pneumonia (VAP) (26%), catheter-related BSI (20.2%) and hospital-acquired pneumonia (HAP) (9.6%). Although not significantly, mortality at all time points was lower for CFDC than COL, while clinical cure was higher in CFDC than COL (66% vs. 44.4%, p = 0.027). Adverse events were more frequent in COL than CFDC-group (38.8% vs. 10%, p < 0.0001), primarily attributed to acute kidney injury (AKI) in the COL group. Patients with bacteremic HAP/VAP treated with CFDC had a significant lower 30-d mortality and higher clinical cure than COL (p = 0.008 and p = 0.0008, respectively). Increment of CCI (p = 0.005), ICU (p = 0.025), SARS-CoV2 (p = 0.006) and ECMO (p < 0.0001) were independently associated with 30-d mortality, while receiving CFDC was not associated with survival.

CONCLUSIONS

CFDC could represent an effective and safe treatment option for CRAB BSI, especially in patients with bacteremic HAP/VAP and frail patients where the risk of acute renal failure during therapy should be avoided.

Ceftazidime/avibactam-resistant meropenem-susceptible KPC-producing Klebsiella pneumoniae: analysis of cases and evaluation of in-vitro activity of fosfomycin-containing combinations

BACKGROUND

Little is known regarding outcomes and optimal therapeutic regimens of infections caused by KPC-producing Klebsiella pneumoniae (KPC-Kp) resistant to ceftazidime/avibactam (CZA) and susceptible to meropenem (MEM). Although in-vitro susceptible to MEM, the possibility of developing MEM resistance overtime is a concern. We described the clinical characteristics of patients with colonization/infection due to KPC-variant with a focus on the in-vitro activity of fosfomycin (FOS)-containing combinations.

MATERIALS/METHODS

Patients with colonization/infection due to KPC-variant were included. FOS susceptibility was performed by agar dilution method. Synergistic activity of FOS-based combinations was evaluated by gradient strip-agar diffusion method. The emergence of in-vitro MEM resistance was also tested.

RESULTS

Eleven patients were included, 8 with infection [4 ventilator-associated pneumonia, 4 bloodstream infections], 3 with colonization. A previous therapy with CZA was administered to all the patients (mean cumulative duration 23 days). All subjects with infection received meropenem, in monotherapy (n=4) or with amikacin (n=2) or fosfomycin (n=2) and achieved clinical cure. A new CZA-susceptible and MEM-resistant KPC-Kp strain was subsequently isolated in 3 patients (27.3%). Meropenem/vaborbactam (MVB) showed high in-vitro activity, while FOS+MEM combination was synergistic in 40% of cases. In-vitro resistance to MEM was observed, with maintenance of CZA resistance.

DISCUSSION

Detection of KPC-variant may occur within the same patient, especially if CZA has been previously administered. Although clinical success has been obtained with carbapenems, the emergence of MEM resistance is a concern. Fosfomycin plus meropenem is synergistic and may represent a valuable combination option for KPC-variant, while MVB may be considered in monotherapy.

IMPORTANCE

The detection of KPC-variants in an endemic setting for KPC-Kp represents a worryingly emerging condition. The optimal therapeutic approach is still unknown and the development of meropenem resistance is a concern, which may finally lead to a therapeutic failure in the clinical practice. In these cases, the addition of fosfomycin to meropenem or a more potent antibiotic such as meropenem/vaborbactam may represent valuable therapeutic options.

Effect of ceftazidime/avibactam plus fosfomycin combination on 30 day mortality in patients with bloodstream infections caused by KPC-producing Klebsiella pneumoniae: results from a multicentre retrospective study

Introduction

The primary outcome of the study was to evaluate the effect on 30 day mortality of the combination ceftazidime/avibactam + fosfomycin in the treatment of bloodstream infections (BSIs) caused by KPC-producing Klebsiella pneumoniae (KPC-Kp).

Materials and methods

From October 2018 to March 2021, a retrospective, two-centre study was performed on patients with KPC-Kp BSI hospitalized at Sapienza University (Rome) and ISMETT-IRCCS (Palermo) and treated with ceftazidime/avibactam-containing regimens. A matched cohort (1:1) analysis was performed. Cases were patients receiving ceftazidime/avibactam + fosfomycin and controls were patients receiving ceftazidime/avibactam alone or in combination with in vitro non-active drugs different from fosfomycin (ceftazidime/avibactam ± other). Patients were matched for age, Charlson comorbidity index, ward of isolation (ICU or non-ICU), source of infection and severity of BSI, expressed as INCREMENT carbapenemase-producing Enterobacteriaceae (CPE) score.

Results

Overall, 221 patients were included in the study. Following the 1:1 match, 122 subjects were retrieved: 61 cases (ceftazidime/avibactam + fosfomycin) and 61 controls (ceftazidime/avibactam ± other). No difference in overall mortality emerged between cases and controls, whereas controls had more non-BSI KPC-Kp infections and a higher number of deaths attributable to secondary infections. Almost half of ceftazidime/avibactam + fosfomycin patients were prescribed fosfomycin without MIC fosfomycin availability. No difference in the outcome emerged after stratification for fosfomycin susceptibility availability and dosage. SARS-CoV-2 infection and ICS ≥ 8 independently predicted 30 day mortality, whereas an appropriate definitive therapy was protective.

Conclusions

Our data show that fosfomycin was used in the treatment of KPC-Kp BSI independently from having its susceptibility testing available. Although no difference was found in 30 day overall mortality, ceftazidime/avibactam + fosfomycin was associated with a lower rate of subsequent KPC-Kp infections and secondary infections than other ceftazidime/avibactam-based regimens.

Molecular characterization of A. baumanni isolates causing co-infections in SARS-COV-2 patients

Background

Respiratory viral infections, such as COVID-19, predispose patients to co-infections leading to increased morbidity and mortality. A. baumannii poses as a serious threat to hospital facilities because of its ability to persist in the environment and acquire multi-drug resistance. The aim of this study was to quantify the extent of A. baumannii cross-infection and identify any gene clonality between isolates in SARS-CoV-2 patients.

Methods

Bacterial isolates of A. baumannii found in patients with SARS-CoV-2 admitted to the main Intensive Care Unit (ICU) of the Umberto I Teaching Hospital of Rome were collected between March 2020 and February 2021. Isolates were typed by pulsed-field electrophoresis to analyse their homology relationships.

Results

Overall, 196 SARS-CoV-2 patients were admitted to the ICU. They were mainly male (N = 138) and aged 63 years on average. Of these, 122 died, and 74 were discharged. A total of 157 strains of A. baumannii were isolated from 74 patients (38%), who had a higher mean hospital stay than patients in whom the bacterial strain had not been isolated (24.6 vs. 12.2 days). The genotypic analysis of 120 isolates revealed two main patterns (A and F) and a few subtypes, especially A8 (43%), A4 (29%), and A11 (10%). Clone A8 was found mainly between October 2020 and February 2021, clone A4 in April-December 2020 and January-February 2021, and A11 in December 2020 and January 2021. The strains were susceptible to colistin only, were isolated mostly from tracheobronchial aspirates (41%) or rectal swabs (35%) and accounted for 56 healthcare-associated infections (33% of which sustained by A4, 38% by A8, and 9% by A11).

Conclusions

The isolation of A. baumannii from patients with COVID-19 highlighted the importance of monitoring co-infections caused by this pathogen, which frequently shows a multi-drug resistant profile that may lengthen the hospital stay. It is essential to implement preventive measures to contain these infections.

Key messages

A. baumanni is a pathogen that needs to be monitored because it may lengthen the hospital stay of SARS-CoV-2 patients. In critically ill patients, the continued growth of multidrug-resistant organisms shows the importance of preventing these infections.

Determinants of prolonged viral RNA shedding in hospitalized patients with SARS-CoV-2 infection

OBJECTIVE

To evaluate determinants of prolonged viral RNA shedding in hospitalized patients with SARS-CoV-2 infection.

MATERIALS AND METHODS

Hospitalized patients with SARS-CoV-2 positive nasopharyngeal RT-PCR were included in a single-center, retrospective study. Patients were divided in 2 groups according to the timing of viral clearance [≤14 days, "early clearance (EC)" and >14 days, "late clearance (LC)"].

RESULTS

179 patients were included in the study (101 EC, 78 LC), with median age 62 years. Median time of viral shedding was 14 days (EC/LC 10 and 19 days, respectively, P < 0.0001). Univariate analyses showed that age, male gender, receiving corticosteroids, receiving tocilizumab, ICU admission, low albumin and NLR ratio were associated with late viral clearance. In the multivariable analysis, older age (P = 0.016), albumin level (P = 0.048), corticosteroids (P = 0.021), and tocilizumab (P = 0.015) were significantly associated with late viral clearance.

CONCLUSIONS

Age, albumin, tocilizumab and corticosteroid treatment were independently associated with a prolonged SARS-CoV-2 RNA shedding.

Co-infection of SARS-CoV-2 with Chlamydia or Mycoplasma pneumoniae: a case series and review of the literature

INTRODUCTION

The novel coronavirus SARS-CoV-2 has spread all over the world causing a global pandemic and representing a great medical challenge. Nowadays, there is limited knowledge on the rate of co-infections with other respiratory pathogens, with viral co-infection being the most representative agents. Co-infection with Mycoplasma pneumoniae has been described both in adults and pediatrics whereas only two cases of Chlamydia pneumoniae have been reported in a large US study so far.

METHODS

In the present report, we describe a series of seven patients where co-infection with C. pneumoniae (n = 5) or M. pneumoniae (n = 2) and SARS-CoV-2 was detected in a large teaching hospital in Rome.

RESULTS AND CONCLUSION

An extensive review of the updated literature regarding the co-infection between SARS-CoV-2 and these atypical pathogens is also performed.

Prevention of surgical site infections in orthopaedic surgery: a synthesis of current recommendations

Despite adopted precautions, surgical site infection (SSI) rate in orthopaedic surgery and its consequences still remain a major problem. Worldwide, infection prevention and control in perioperative settings are considered of primary importance for every healthcare system. The management of perioperative infections carries a heavy psychological and financial burden, since patients who experience SSI have increased hospital length of stay, morbidity and mortality rates, and higher hospital costs. As the treatment of such infections is particularly difficult in the presence of an implanted biomaterial, the prevention of SSI in orthopaedic surgery represents a challenging key issue, requiring the integration of a range of measures before, during and after surgery. In fact, over the years several aspects of SSI prevention have been studied in order to identify the best SSI prevention strategies and set out appropriate clinical practices. This article will review and summarize the recent international guidelines released on this subject together with other published relevant evidence.

Multimodal surveillance of healthcare associated infections in an intensive care unit of a large teaching hospital

BACKGROUND

Healthcare-associated infections (HAIs), or nosocomial infections, represent a significant burden in terms of mortality, morbidity, length of stay and costs for patients hospitalized in intensive care units (ICUs). Surveillance systems are recommended by national and international institutions to gather data on HAIs in order to develop and evaluate interventions that reduce the risk of HAIs.

STUDY DESIGN

Here we describe the methodology and the results of the surveillance system implemented in the ICU of the Policlinico Umberto I, a large teaching hospital in Rome, from April 2016 to October 2018.

METHODS

The multimodal infection surveillance system integrates four different approaches: i) active surveillance of inpatients; ii) environmental microbiological surveillance; iii) surveillance of isolated microorganisms; and iv) behavioral surveillance of healthcare personnel. Data were collected on catheter-related bloodstream infections, ventilation-associated pneumonia, catheter-associated urinary tract infections and primary bloodstream infections that developed in patients after 48 h in the ICU. For environmental surveillance 14 points were selected for sampling (i.e. bed edges, medication carts, PC keyboards, sink faucets). The system of active surveillance of HAIs also included surveillance of microorganisms, consisting of the molecular genotyping of bacterial isolates by pulsed-field gel electrophoresis (PFGE). From 1 November 2016, monitoring of compliance with guidelines for hand hygiene (HH) and proper glove or gown use by healthcare personnel was included in the surveillance system. After the first six months (baseline phase), a multimodal intervention to improve adherence to guidelines by healthcare personnel was conducted with the ICU staff.

RESULTS

Overall, 773 patients were included in the active surveillance. The overall incidence rate of device-related HAIs was 14.1 (95% CI: 12.2-16.3) per 1000 patient-days. The monthly device-related HAI incident rate showed a decreasing trend over time, with peaks of incidence becoming progressively lower. The most common bacterial isolates were Klebsiella pneumoniae (20.7%), Acinetobacter baumannii (17.2%), Pseudomonas aeruginosa (13.4%) and Staphylococcus aureus (5.4%). Acinetobacter baumannii and Klebsiella pneumoniae showed the highest proportion of isolates with a multidrug-resistant profile. A total of 819 environmental samples were collected, from which 305 bacterial isolates were retrieved. The most frequent bacterial isolates were Acinetobacter baumannii (27.2%), Staphylococcus aureus (12.1%), Enterococcus faecalis (11.1%), Klebsiella pneumoniae (5.2%) and Pseudomonas aeruginosa (4.7%). All Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae environmental isolates were at least multidrug-resistant. Genotyping showed a limited number of major PFGE patterns for both clinical and environmental isolates of Klebsiella pneumoniae and Acinetobacter baumannii. Behavioral compliance rates significantly improved from baseline to post-intervention phase.

CONCLUSIONS

By integrating information gathered from active surveillance, environmental microbiological surveillance, surveillance of bacterial isolates and behavioral surveillance of healthcare personnel, the multimodal infection surveillance system returned a precise and detailed view of the infectious risk and microbial ecology of the ICU.

Predictors of outcome in patients with severe sepsis or septic shock due to extended-spectrum β-lactamase-producing Enterobacteriaceae

PURPOSE

There are few data in the literature regarding sepsis or septic shock due to extended-spectrum β-lactamases (ESBL)-producing Enterobacteriaceae (E). The aim of this study was to assess predictors of outcome in septic patients with bloodstream infection (BSI) caused by ESBL-E.

METHODS

Patients with severe sepsis or septic shock and BSI due to ESBL-E were selected from the INCREMENT database. The primary endpoint of the study was the evaluation of predictors of outcome after 30 days from development of severe sepsis or septic shock due to ESBL-E infection. Three cohorts were created for analysis: global, empirical-therapy and targeted-therapy cohorts.

RESULTS

367 septic patients were analysed. Overall mortality was 43.9% at 30 days. Escherichia coli (62.4%) and Klebsiella pneumoniae (27.2%) were the most frequent isolates. β-lactam/β-lactamase inhibitor (BLBLI) combinations were the most empirically used drug (43.6%), followed by carbapenems (29.4%). Empirical therapy was active in vitro in 249 (67.8%) patients, and escalation of antibiotic therapy was reported in 287 (78.2%) patients. Cox regression analysis showed that age, Charlson Comorbidity Index, McCabe classification, Pitt bacteremia score, abdominal source of infection and escalation of antibiotic therapy were independently associated with 30-day mortality. No differences in survival were reported in patients treated with BLBLI combinations or carbapenems in empirical or definitive therapy.

CONCLUSIONS

BSI due to ESBL-E in patients who developed severe sepsis or septic shock was associated with high 30-day mortality. Comorbidities, severity scores, source of infection and antibiotic therapy escalation were important determinants of unfavorable outcome.

Risk factors for recurrence in patients with Clostridium difficile infection due to 027 and non-027 ribotypes

OBJECTIVES

Our objective was to evaluate factors associated with recurrence in patients with 027+ and 027- Clostridium difficile infection (CDI).

METHODS

Patients with CDI observed between January and December 2014 in six hospitals were consecutively included in the study. The 027 ribotype was deduced by the presence of tcdB, tcdB, cdt genes and the deletion Δ117 in tcdC (Xpert® C. difficile/Epi). Recurrence was defined as a positive laboratory test result for C. difficile more than 14 days but within 8 weeks after the initial diagnosis date with reappearance of symptoms. To identify factors associated with recurrence in 027+ and 027- CDI, a multivariate analysis was performed in each patient group. Subdistributional hazard ratios (sHRs) and 95% confidence intervals (95%CIs) were calculated.

RESULTS

Overall, 238 patients with 027+ CDI and 267 with 027- CDI were analysed. On multivariate analysis metronidazole monotherapy (sHR 2.380, 95%CI 1.549-3.60, p <0.001) and immunosuppressive treatment (sHR 3.116, 95%CI 1.906-5.090, p <0.001) were factors associated with recurrence in patients with 027+ CDI. In this patient group, metronidazole monotherapy was independently associated with recurrence in both mild/moderate (sHR 1.894, 95%CI 1.051-3.410, p 0.033) and severe CDI (sHR 2.476, 95%CI 1.281-4.790, p 0.007). Conversely, non-severe disease (sHR 3.704, 95%CI 1.437-9.524, p 0.007) and absence of chronic renal failure (sHR 16.129, 95%CI 2.155-125.000, p 0.007) were associated with recurrence in 027- CDI.

CONCLUSIONS

Compared to vancomycin, metronidazole monotherapy appears less effective in curing CDI without relapse in the 027+ patient group, independently of disease severity.

Role of biomarkers in adult sepsis and their application for a good laboratory practice: a pilot study

This study measured Procalcitonin (PCT), Presepsin (PRE-S) and pro-Adrenomedullin (pro-ADM) in intensive care unit (ICU) patient’s blood to assess their contribution to accurate diagnosis of sepsis and potential predictive impact on prognosis. The final aim was to improve the use of infection biomarkers for optimizing the impact of laboratory medicine on clinical outcomes, focusing on the good management of resources designed to produce maximum effectiveness and efficiency. Sixty-four adult patients were studied during their hospitalization in ICU; blood samples were collected and categorized according to their clinical diagnosis and illness severity, and sepsis marker levels were measured on automated immunoassay platforms. PCT, PRE-S and pro-ADM infection markers were significantly lower in controls than in sepsis or septic shock groups. The area under the curve, by ROC curve analysis, was 0.945 for PCT, 0.756 for PRE-S and 0.741 for pro-ADM. Sepsis diagnostic accuracy was not improved by combining PCT, PRE-S and pro-ADM measures. Preliminary data demonstrated that, despite PRE-S and pro-ADM being able to differentiate between septic and non-septic patients with accuracy, PCT remains the most reliable marker available. The results obtained still do not allow us to consider a combination of markers, because it would merely increase laboratory costs without improving diagnostic performance. Furthermore, the results confirm a possible prognostic role of pro-ADM in septic states, but no correlation between biomarker levels and survival at 48 h was detected. Hence PCT, PRE-S, nor pro-ADM can be used to predict short-term prognosis.

Predictors of mortality in nursing-home residents with pneumonia: a multicentre study

OBJECTIVES

To evaluate predictors of mortality in patients residing in nursing-homes (NHs) or long-term care facilities (LTCFs) with diagnosis of NH-acquired pneumonia (NHAP).

METHODS

We conducted an observational, prospective study (December 2013-December 2015) of patients residing in nine NHs/LTCFs of Central and Northern Italy with diagnosis of NHAP. Data on demographics, comorbidities, microbiology, and therapies were entered into an electronic database. To identify risk factors associated with 30-day mortality, we performed univariable and multivariable analyses, and predictors were internally validated using a bootstrap resampling procedure. We derived a prediction rule using the coefficients obtained from the multivariable logistic regression. The model obtained was assessed using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Overall, 446 patients with NHAP were included in the final cohort. The median age was 80 (IQR 75-87) years. A definite aetiology was obtained in 120 (26.9%) patients; of these, 66 (55%) had a culture positive for a multidrug-resistant pathogen. The 30-day mortality was 28.7%. On multivariate analysis, malnutrition (OR 7.8; 95% CI 3-20.2, 2 points), bilateral pneumonia (OR 3.7; 95% CI 1.4-9.8, 1 point), acute mental status deterioration (OR 6.2; 95% CI 2.2-17.6, 2 points), hypotension (OR 7.7; 95% CI 2.3-24.9, 2 points), and PaO₂/FiO₂ ratio ≤250 (OR 7.4; 95% CI 2.2-24.2, 2 points) were independently associated with 30-day mortality. The derived prediction rule showed an AUROC of 0.83 (95% CI 0.78-0.87, p <0.001).

CONCLUSIONS

NH residents with pneumonia have specific risk factors associated with 30-day mortality. Malnutrition and acute mental change appear as major determinants of death in this population.

Assessment of risk factors for candidemia in non-neutropenic patients hospitalized in Internal Medicine wards: A multicenter study

BACKGROUND

An increasing prevalence of candidemia has been reported in Internal Medicine wards (IMWs). The aim of our study was to identify risk factors for candidemia among non-neutropenic patients hospitalized in IMWs.

METHODS

A multicenter case-control study was performed in three hospitals in Italy. Patients developing candidemia (cases) were compared to patients without candidemia (controls) matched by age, time of admission and duration of hospitalization. A logistic regression analysis identified risk factors for candidemia, and a new risk score was developed. Validation was performed on an external cohort of patients.

RESULTS

Overall, 951 patients (317 cases of candidemia and 634 controls) were included in the derivation cohort, while 270 patients (90 patients with candidemia and 180 controls) constituted the validation cohort. Severe sepsis or septic shock, recent Clostridium difficile infection, diabetes mellitus, total parenteral nutrition, chronic obstructive pulmonary disease, concomitant intravenous glycopeptide therapy, presence of peripherally inserted central catheter, previous antibiotic therapy and immunosuppressive therapy were factors independently associated with candidemia. The new risk score showed good area under the curve (AUC) values in both derivation (AUC 0.973 95% CI 0.809-0.997, p<0.001) and validation cohort (0.867 95% CI 0.710-0.931, p<0.001). A threshold of 3 leads to a sensitivity of 87% and a specificity of 83%.

CONCLUSION

Non-neutropenic patients admitted in IMWs have peculiar risk factors for candidemia. A new risk score with a good performance could facilitate the identification of candidates to early antifungal therapy.

Current and future trends in antibiotic therapy of acute bacterial skin and skin-structure infections

In 2013 the US Food and Drug Administration (FDA) issued recommendations and guidance on developing drugs for treatment of skin infection using a new definition of acute bacterial skin and skin-structure infection (ABSSSI). The new classification includes cellulitis, erysipelas, major skin abscesses and wound infection with a considerable extension of skin involvement, clearly referring to a severe subset of skin infections. The main goal of the FDA was to better identify specific infections where the advantages of a new antibiotic could be precisely estimated through quantifiable parameters, such as improvement of the lesion size and of systemic signs of infection. Before the spread and diffusion of methicillin-resistant Staphylococcus aureus (MRSA) in skin infections, antibiotic therapy was relatively straightforward. Using an empiric approach, a β-lactam was the preferred therapy and cultures from patients were rarely obtained. With the emergence of MRSA in the community setting, initial ABSSSI management has been changed and readdressed. Dalbavancin, oritavancin and tedizolid are new drugs, approved or in development for ABSSSI treatment, that also proved to be efficient against MRSA. Dalbavancin and oritavancin have a long half-life and can be dosed less frequently. This in turn makes it possible to treat patients with ABSSSI in an outpatient setting, avoiding hospitalization or potentially allowing earlier discharge, without compromising efficacy. In conclusion, characteristics of long-acting antibiotics could represent an opportunity for the management of ABSSSI and could profoundly modify the management of these infections by reducing or in some cases eliminating both costs and risks of hospitalization.

Predictors of outcome in ICU patients with septic shock caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae

The aim of this study was to identify factors associated with mortality in intensive care unit patients with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) septic shock. A retrospective analysis of intensive care unit patients with KPC-Kp infection and septic shock observed in a large teaching hospital from November 2010 to December 2014 was performed. A total of 111 patients were included in the study. The most frequent source of infection was unknown-focus bacteraemia in 53 patients (47.7%). The rate of resistance to colistin was 51.3%; 30-day mortality was reported for 44 patients (39.6%). Surviving patients were more frequently treated with an initial therapy (within 24 hours) including two or more antibiotics displaying in vitro activity against the isolated KPC-Kp strain (41.8 vs. 18.1%, p 0.01) and were also more likely to receive a definitive therapy including two or more in vitro active antibiotics (85.1 vs. 15.9%, p <0.001). Cox regression analysis revealed that a colistin-containing antibiotic regimen (hazard ratio (HR) 0.21, confidence interval (CI) 95% 0.05-0.72, p <0.001), use of two or more in vitro active antibiotics as definite therapy (HR 0.08, CI 95% 0.02-0.21, p <0.001) and control of removable source of infection (HR 0.14, CI 95% 0.04-0.25, p <0.001) were associated with favourable outcome; colistin resistance (HR 8.09, CI 95% 3.14-11.23, p 0.001) and intra-abdominal source of infection (HR 2.92, CI 95% 2.11-4.12, p 0.002) were associated with death. In conclusion, use of a definitive therapy with at least two antibiotics displaying in vitro activity against the KPC-Kp isolates was the most important determinant of favourable outcome, whilst isolation of colistin-resistant strains was associated with death in septic patients with KPC-Kp infection.

Changed epidemiology of ICU acquired bloodstream infections over 12 years in an Italian teaching hospital

BACKGROUND

We compared the etiology of 203 ICU-acquired laboratory confirmed bloodstream infections (LC-BSI) prospectively collected between January 2000-December 2007 (first period) with 83 LC-BSI recorded between January 2010-December 2012 (second period), after the diffusion in 2008 of K. pneumoniae expressing carbapenem-resistance due to K. pneumoniae carbapenemases production (KPC-CR-Kp).

METHODS

In the general ICU of teaching hospital "Umberto I" in Rome, all ICU-acquired LC-BSI episodes occurring in patients admitted to ICU≥48h were included. Baseline characteristics, clinical features, antimicrobial resistance and outcome were recorded. All isolated strains multidrug resistance (MDR) were evaluated according to the European Centre for Disease Control (ECDC) guidelines.

RESULTS

Overall the study included 329 isolates, 214 in 2000-2007 and 115 in 2010-2012. In the second period we registered a Gram-positive reduction (55.1% vs. 26.9%; P<0.01) and Gram-negative increase (40.2% vs. 69.6%; P<0.01). In 2000-2007 staphylococci were responsible for 45.8% LC-BSI's, whereas 18.3% during 2010-2012. Enterobacteriaceae increased dramatically (15.4% vs. 39.2%; P<0.01), especially Klebsiella spp. (5.6% vs. 31.3%; P<0.01). LC-BSI associated mortality decreased among Gram-positive (56.8% vs. 51.6%), but increased in Gram-negative (41.9% vs. 60.0%; P<0.03), especially in Enterobacteriaceae (RR 2.13; 95% CI 1.21 - 3.73; P<0.01). MDR increased remarkably among Enterobacetriaceae (51.5% vs. 73.3%). The study highlighted the associated mortality for Enterobacteriaceae when comparing MDR to non-MDR microorganisms.

CONCLUSION

ICU-acquired LC-BSI etiology shifted from Gram-positive to Gram-negative during the study period in our ICU. Also associated mortality decreased among the former, whereas it increased in the latter. Last MDR increased enormously among Enterobacteriaceae with the diffusion of KPC (75% of strains), adding significantly to associated mortality (RR 2.17; 1.16-4.05; P<0.01).

Risk factors and clinical outcomes of candidaemia in patients treated for Clostridium difficile infection

The alterations occurring in the intestinal flora during Clostridium difficile infection (CDI) may promote the translocation of Candida to the blood and the development of candidaemia. The aim of our study was to analyse clinical findings of these patients to determine the risk factors associated with the development of candidaemia subsequent to CDI. We compared 35 patients with candidaemia subsequent to CDI with 105 patients with CDI. Patients with candidaemia showed more severe infections and higher mortality. The ribotype 027 strain and vancomycin treatment at ≥ 1000 mg/day were prevalent in patients developing candidaemia. CDI may predispose to the translocation of Candida.

Role of empirical and targeted therapy in hospitalized patients with bloodstream infections caused by ESBL-producing Enterobacteriaceae

BACKGROUND

Bloodstream infection (BSI) due to extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae are a major cause of in-hospital mortality. The effect on survival of empirical and targeted antibiotic therapy in these patients remains controversial.

METHODS

A prospective cohort study was conducted analyzing data from 94 patients (age 59 ± 21 years) with BSI due to ESBL producing strains (Sixty-one E. coli, 26 K. pneumoniae, 4 Proteus spp and 3 Enterobacter spp).

RESULTS

Risk factors associated with 21-day mortality at univariate analysis were: recent administration of antibiotic therapy (p=0.049), higher SOFA score (p=0.05), ICU stay (p <0.01), hypotension at presentation (p =0.001) or septic shock (p <0.001) and bacteremia from source other than urinary tract (p=0.03). Regardless of antibiotic class used, no differences in survival were noted between patients receiving or not adequate initial antimicrobial treatment (37.1% vs 23.7% p=0.23); on the other hand, compared with the administration of other in vitro active antibiotics, the use of carbapenem as definitive therapy was associated with a significantly lower 21-day mortality (54.3% vs 28.5% p=0.02).

CONCLUSIONS

These findings suggest that the administration of an adequate initial therapy is not associated with mortality in hospitalized patients with BSI due to Enterobacteriaceae. The severity of clinical conditions at presentation and the administration of carbapenems as definitive therapy seems to be really important in affecting the outcome of patients with BSI due to ESBL producing strains.

A cluster of fulminant Clostridium difficile colitis in an intensive care unit in Italy

We describe, for the first time, a cluster of lethal fulminant health-care associated Clostridium difficile (CD) colitis in Italy, observed in the intensive care unit (ICU) of an Italian tertiary care hospital in Rome. For all cases the cause of ICU admission was CD-related septic shock. Three out of seven patients were residents in a long-term care facility in Rome, and the others had been transferred to the ICU from different medical wards of the same hospital. Five patients died within 96 h of ICU admission. Because of a clinical deterioration after 4 days of adequate antibiotic therapy, two patients underwent subtotal colectomy: both of them died within 30 days of surgical intervention. In four cases, ribotyping assay was performed and ribotype 027 was recognized. This high mortality rate could be attributable to three findings: the extent of disease severity induced by the strain 027, the delay in antimicrobial therapy administration, and the lack of efficacy of the standard antibiotic treatment for fulminant CD colitis compared to an earlier surgical approach. In order to contain a CD infection epidemic, control and surveillance measures should be implemented, and empirical therapy should be administered. Because of potential 027 ribotype CD spread in Italy, CDI should be regarded with a high index of suspicion in all patients presenting with shock and signs or symptoms suggesting abdominal disease, and an early surgical approach should be considered.

Antimicrobial Susceptibility, Biochemical and Genetic Profiles ofStaphylococcus haemolyticusStrains Isolated from the Bloodstream of Patients Hospitalized in Critical Care Units

Staphylococcus haemolyticus strains (n=20), responsible of blood stream infections, were consecutively isolated from patients hospitalized in two different wards at high risk of infection. Strains displayed high rate of resistance to oxacillin (90%). All strains but two with decreased susceptibility (MIC = 4 microg/mL), were sensitive to vancomycin. Ten strains were resistant to teicoplanin. Among the strains susceptible to glycopeptides, three displayed heteroresistance to vancomycin and seven to teicoplanin, when tested by Etest technique with 2 x McFarland inoculum. Biochemical reactions allowed to assign strains to eight biotypes, with 11 strains clustering under two main biotype A and biotype B. Pulsed-field-gel-electrophoresis (PFGE) identified 11 different PFGE-types. Seven strains grouping under the major PFGE-type 1 and three strains clustering in PFGE-type 2, closely correlated to biotype A and biotype B respectively. Seven teicoplanin-resistant isolates clustered in the PFGE-type 1, two in the PFGE-type 2 and one in PFGE-type 5. Therefore, teicoplanin-resistant strains were biochemically and genetically related and clonally distributed, despite different clones of S. haemolyticus circulated in the units during the study period.

SIMIFF study: Italian fungal registry of mold infections in hematological and non-hematological patients

Purpose

We compared the risk factors, the diagnostic tools and the outcome of filamentous fungal infections (FFIs) in hematological patients (HAEs) and non-hematological patients (non-HAEs).

Methods

Prospective surveillance (2009–2011) of proven and probable FFIs was implemented in 23 Italian hospitals.

Results

Out of 232 FFIs, 113 occurred in HAEs and 119 in non-HAEs. The most frequent infection was invasive aspergillosis (76.1 % for HAEs, 56.3 % for non-HAEs), and the localization was principally pulmonary (83.2 % for HAEs, 74.8 % for non-HAEs). Neutropenia was a risk factor for 89.4 % HAEs; the main underlying condition was corticosteroid treatment (52.9 %) for non-HAEs. The distribution of proven and probable FFIs was different in the two groups: proven FFIs occurred more frequently in non-HAEs, whereas probable FFIs were correlated with the HAEs. The sensitivity of the galactomannan assay was higher for HAEs than for non-HAEs (95.3 vs. 48.1 %). The overall mortality rate was 44.2 % among the HAEs and 35.3 % among the non-HAEs. The etiology influenced the patient outcomes: mucormycosis was associated with a high mortality rate (57.1 % for HAEs, 77.8 % for non-HAEs).

Conclusions

The epidemiological and clinical data for FFIs were not identical in the HAEs and non-HAEs. The differences should be considered to improve the management of FFIs according to the patients’ setting.

Candidemia in Neurosurgical Intensive Care Unit: preliminary analysis of the effect of topical Nystatin prophylaxis and adequate source control on patients with early tracheostomy intubation

INTRODUCTION

The present study represents a preliminary evaluation of the impact of topical nystatin prophylaxis administration and adequate CVC management on reducing the chance of developing candidemia in neurosurgical intensive care unit (NICU) patients.

MATERIALS AND METHODS

We conducted a case-control study at the nine bed NICU of the Policlinico "Umberto I" teaching hospital in Rome, Italy, during the period from January 2011 to July 2012. We compared eight patients with culture proven Candida bloodstream infection (CBSI) with a control group of 19 patients who did not have evidence of CBSI.

RESULTS

When the CBSI group was compared with the control group, the former were more likely than controls to not have received nystatin prophylaxis and adequate catheter care (p= 0,008). When CBSI group was matched with patients with no adequate source control and nystatin prophylaxis, average NICU stay (71.13 days vs 19.0 days) was significant (mean difference = -52.12 days, 95% CI -97.11 to -7.14, p= 0.028). The same was true for mean time of glucocorticoid exposure (mean difference = -10.5 days, 95% CI -17.35 to -3.65, p<0.01). Binary logistic regression analysis demonstrated no significant association between topical nystatin prophylaxis (p= 0.99), length of NICU stay (p= 0.99), time of glucocorticoid exposure (p= 0.99) and candidemia.

CONCLUSION

Topical prophylaxis with nystatin and adequate source control proved to be effective in preventing invasive candidiasis in patients admitted to the NICU.

Extended Spectrum Beta-Lactamase-ProducingKlebsiella pneumoniaeOutbreaks During a Third Generation Cephalosporin Restriction Policy

In spite of the adoption of third generation cephalosporin restriction policies, two independent outbreaks by Extended Spectrum Beta-Lactamase (ESBL)-producing Klebsiella pneumoniae occurred in two different wards (Neonatal Intensive Care Unit, NICU and Neurosurgery) of a teaching hospital in Rome, Italy. In the former 19 infected neonates were reported, whereas in the latter there were 10 infected patients. In both wards no differences were observed in the mortality rates in periods of outbreak and those with no outbreak. Molecular typing on a total of 19 isolated strains was carried out and restriction patterns were compared. The PFGE showed that nine isolates responsible for infection in the NICU were all included in three closely related clusters. In Neurosurgery nine strains out of ten were strictly related and part of an outbreak occurring between August-December 2003, while one isolate was temporarily (February 2003) and genetically (seven band differences) unrelated to the outbreak strains. When ESBL producing K. pneumoniae clusters from the two wards (NICU vs Neurosurgery) were compared, they appeared to be completely different both for their genotype pattern and plasmid type or presence, thus demonstrating cross transmission by two different genotypes.

Methicillin-Resistant Staphylococcal Bacteremia in Patients with Hematologic Malignancies: Clinical and Microbiological Retrospective Comparative Analysis ofS. haemolyticus, S. epidermidisandS. aureus

Although Staphylococcus haemolyticus (SH) represents an emerging etiology of methicillin-resistant (MR) coagulase-negative staphylococcal nosocomial bacteremia, little is known of clinical significance of this infection. Thus, we performed case-control retrospective comparative analysis of MRSH bacteremias (MRSHB), methicillin-resistant S. epidermidis bacteremias (MRSEB), and methicillin-resistant S. aureus bacteremias (MRSAB) in patients with hematologic malignancies. Most patients in the three groups were neutropenic and had a central venous catheter (CVC) in place at the onset of bacteremia. However, MRSHB patients had a CVC in place prior to bacteremia for a time significantly more prolonged than MRSEB and MRSAB ones (p<0.05). Severe sepsis or septic shock were more common in patients with MRSAB as compared with MRSHB (p=0.02). Nosocomial attributable mortality rate was very low in the 3 study groups (0 to 5.4%) and only two patients developed metastatic infections. Overall, reduced susceptibility to teicoplanin was observed in 19 (47.5%) MRSH and in 4 (10%) MRSE isolates. Resistance to teicoplanin was observed in 6 isolates, all MRSH. Reduced susceptibility or resistance to vancomycin was observed in 2 isolates, both MRSH. All MRSA isolates were susceptible to the glycopeptides. Comparison between cases of bacteremia in patients with MRSH isolates with reduced susceptibility to teicoplanin and those with susceptible MRSH did not reveal significant differences in the clinical-microbiological response to teicoplanin therapy and outcome. Our results seem to suggest that MRSHB in hematologic patients is associated with low morbidity and mortality rates. MRSH frequently shows a reduced susceptibility to teicoplanin; however these in vitro data do not seem associated with an unfavorable clinical response to teicoplanin therapy for MRSHB in patients with hematologic malignancies.

High rate of colistin resistance among patients with carbapenem-resistant Klebsiella pneumoniae infection accounts for an excess of mortality

Carbapenem-resistant Klebsiella pneumoniae (CR-KP) is becoming a common cause of healthcare-associated infection in Italy, with high morbidity and mortality. Prevalent CR-KP clones and resistance mechanisms vary between regions and over time. Therapeutic approaches and their impact on mortality have to be investigated. We performed a prospective study of patients with CR-KP isolation, hospitalized in nine hospitals of Rome, Italy, from December 2010 to May 2011, to describe the molecular epidemiology, antibiotic treatment and risk factors for mortality. Overall, 97 patients (60% male, median age 69 years) were enrolled. Strains producing blaKPC-3 were identified in 89 patients, blaVIM in three patients and blaCTX-M-15 plus porin defects in the remaining five patients. Inter-hospital spread of two major clones, ST512 and ST258, was found. Overall, 36.1% and 20.4% of strains were also resistant to colistin and tigecycline, respectively. Infection was diagnosed in 91 patients who received appropriate antibiotic treatment, combination therapy and removal of the infectious source in 73.6%, 59.3% and 28.5% of cases, respectively. Overall, 23 different antibiotic regimens were prescribed. In-hospital mortality was 25.8%. Multivariate analysis adjusted for appropriate treatment, combination therapy and infectious-source removal, showed that Charlson comorbidity score, intensive-care unit onset of infection, bacteraemia and infection due to a colistin-resistant CR-KP strain were independent risk factors for mortality. The spread of clones producing K. pneumoniae carbapenemases, mainly ST258, is currently the major cause of CR-KP infection in central Italy. We observed a high rate of resistance to colistin that is independently associated with worse outcome.

Patient risk factors for outer membrane permeability and KPC-producing carbapenem-resistant Klebsiella pneumoniae isolation: results of a double case-control study

BACKGROUND

In the 1,200-bed university hospital "Umberto I" in Rome, Italy, we observed a dramatic substitution of a precedingly well-documented Klebsiella pneumoniae clone (ST37) with ertapenem resistance by outer membrane permeability modification (Porin-ER-Kp) with a new K. pneumoniae strain expressing carbapenem resistance due to K. pneumoniae carbapenemase production (KPC-CR-Kp). A case-case-control study was carried out to evaluate risk factors for Porin-ER-Kp and KPC-CR-Kp isolation.

METHODS

All patients with hospital-acquired K. pneumoniae isolation between July 2008 and June 2011 were included. Two case groups including patients harbouring KPC-CR-Kp and Porin-ER-Kp were analysed, with a third control group from whom carbapenem-susceptible K. pneumoniae (CS-Kp) were isolated.

RESULTS

Forty-four KPC-CR-Kp cases, 39 Porin-ER-Kp cases and 60 CS-Kp controls were analysed. During the 3-year study, a specific Porin-ER-Kp endemic clone (ST37) was substituted by a new KPC-CR-Kp clone (ST512). Breakthrough bacteraemias occurred in 21 out of 26 KPC-CR-Kp group bloodstream infections (BSIs); nine of these developed during carbapenem therapy and seven with colistin and/or tigecycline therapy. In 13 Porin-ER-Kp BSIs, breakthrough bacteraemias developed in eight patients and four during carbapenem therapy. In the multivariable analysis, KPC-CR-Kp isolates were associated with carbapenems [odds ratio (OR) 7.74; 95 % confidence interval (CI) 1.70-35.2; p < 0.01) and endoscopy (OR 6.71; 95 % CI 1.25-36.0; p < 0.03). Porin-ER-Kp independent risk factors included second-generation cephalosporins (OR 25.7; 95 % CI 3.20-206.8; p < 0.01), carbapenems (OR 19.1; 95 % CI 4.34-83.9; p < 0.001), acute renal failure (OR 7.17; 95 % CI 1.33-38.6; p < 0.03), endoscopy (OR 6.12; 95 % CI 1.46-25.6; p < 0.02) and third-generation cephalosporins (OR 5.3; 95 % CI 1.34-20.9; p < 0.02).

CONCLUSIONS

Porin-ER-Kp strains needed major antimicrobial pressure compared to KPC-CR-Kp to express resistance. KPC-CR-Kp substituted Porin-ER-Kp strains, causing more infections. KPC-CR-Kp breakthrough bacteraemia occurred even under therapy with tigecycline or colistin, underlining that an antibiotic stewardship programme is needed urgently.

Laboratory confirmed bloodstream infection aetiology in an intensive care unit: eight years study

To evaluate laboratory confirmed bloodstream infection (LC-BSI) aetiology we carried out a prospective study in the general 13 bed ICU of the teaching hospital Policlinico Umberto I in Rome. According to CDC case definitions for LC-BSI, all patients admitted >48h between 2000-2007 to ICU were included. Risk factors (i.e. age, sex, SAPS II), invasive procedures (i.e. endotracheal intubation, vascular and urinary catheterisation), microbiological isolates and their antibiotic susceptibility were screened. Overall 1741 patients (64.8% males, 35.2% females) were included, mean age was 58.1 +/- 19.8, SAPS II score 45.1 +/- 17 and ICU stay 14.0 +/- 21.1 days. Finally, 167 (9.6%) patients developed 203 (11.7%) ICU-acquired LC-BSI and sources of infection were CVC (39.8%), unknown (39.3%), respiratory tract (12.4%), surgical wound (6.5%) and urinary tract (2.0%). Between 2000 and 2007 the incidence of LC-BSI/1000 patient days (14.8 per thousands vs. 7.8 per thousands: p<0.05) and LC-BSI/1000 CVC days (20.7 per thousands vs. 11.4 per thousands; p<0.05) decreased. The onset of infection followed ICU admission by 19.5 +/- 17.7 (mean) and 13 days (median). Crude mortality was 34.8%, and mortality associated with LC-BSI showed a RR 1.61; 95%CI 1.37 - 1.89; p<0.01. The most common pathogens were coagulase negative staphylococci (CNS) (26.2%), methicillin-resistant Staphylococcus aureus (MRSA) (14.9%), Pseudomonas aeruginosa (13.5%), enterococci (9.3%) and Acinetobacter bawnumannii (7.5%). Onset time (days) between ICU admission and LC-BSI was higher (p<0.01) among Gram-negative (22.9 +/- 18.4) compared to Gram-positive (16.6 +/- 15.9), fungi (23.8 +/- 25.3). High early death (<7 days after BSI diagnosis) was associated to A. baumannii (37.5%), Candida spp. (30.0%) and S. aureus (29.7%). Staphylococci presented a very high methicillin resistance (>85%). P. aeruginosa and A. baumannii showed respectively 25% and 68.7% multidrug-resistance. Over 1/3 of Eneterobacteriaceae isolates were extended spectrum beta-lactamase (ESBL), but non resulted resistant to carbapenems. Surveillance showed a high incidence of LC-BSI associated to invasive procedures and the presence of multiresistant bacteria.

Diagnosis and management of skin and soft-tissue infections (SSTI): a literature review and consensus statement on behalf of the Italian Society of Infectious Diseases and International Society of Chemotherapy

Skin and soft-tissue infections (SSTIs) are among the most common bacterial infections, posing considerable diagnostic and therapeutic challenges and resulting in significant morbidity and mortality among patients as well as increased healthcare costs. eight members of the SSTI working group of the Italian Society of infectious Diseases prepared a draft of the statements, grading the quality of each piece of evidence after a careful review of the current literature using MEDLINE database and their own clinical experience. Statements were graded for their strength and quality using a system based on the one adopted by the Infectious Diseases Society of America (IDSA). The manuscript was successively reviewed by seven members of the SSTI working group of the international Society of Chemotherapy, and ultimately re-formulated by all e xperts. the microbiological and clinical aspects together with diagnostic features were considered for uncomplicated and complicated SSTIs. Antimicrobial therapy was considered as well -both empirical and targeted to methicillin-resistant Staphylococcus aureus (MRSA) and/or other main pathogens.

Invasive pulmonary aspergillosis in non-neutropenic patients: analysis of a 14-month prospective clinical experience

Invasive pulmonary aspergillosis (IPA) is one of the major causes of morbidity and mortality in severely immunocompromised patients, but recently several authors have reported the occurrence of IPA in liver cirrhosis, chronic obstructive pulmonary disease (COPD) patients, most of whom, but not all, were receiving steroid treatment, with a very high mortality rate. The detection of galactomannan performed in respiratory specimens is a new valuable test for the diagnosis of probable IPA, even in non-neutropenic high risk patients. Since the frequency and clinical impact of IPA in non-hematologic patients is not well known, it seemed rational to us to attempt a prospective study evaluating all patients hospitalized in a university hospital for whom an infectious Diseases consultation was required. This 14-month survey in our hospital, using recently recommended diagnostic criteria, seems to suggest an emerging role of IPA in these patients who may have a higher mortality rate than their neutropenic peers, and provides preliminary evidence that early diagnosis and prompt initiation of antifungal therapy may improve the ultimate outcome of their IPA.

Italian guidelines for diagnosis, prevention, and treatment of invasive fungal infections in solid organ transplant recipients

Use of various induction regimens, of novel immunosuppressive agents, and of newer prophylactic strategies continues to change the pattern of infections among solid organ transplant (SOT) recipients. Although invasive fungal infections (IFIs) occur at a lower incidence than bacterial and viral infections in this population, they remain a major cause of morbidity and mortality worldwide. In March 2008, a panel of Italian experts on fungal infections and organ transplantation convened in Castel Gandolfo (Rome) to develop consensus guidelines for the diagnosis, prevention, and treatment of IFIs among SOT recipients. We discussed the definitions, microbiological and radiological diagnoses, prophylaxis, empirical treatment, and therapy of established disease. Throughout the consensus document, recommendations as clinical guidelines were rated according to the standard scoring system of the Infectious Diseases Society of America and the United Stated Public Health Service.

Changing Italian nosocomial-community trends and heteroresistance in Staphylococcus aureus from bacteremia and endocarditis

Bloodstream infections due to Staphylococcus aureus (BSI) are serious infections both in hospitals and in the community, possibly leading to infective endocarditis (IE). The use of glycopeptides has been recently challenged by various forms of low-level resistance. This study evaluated the distribution of MSSA and MRSA isolates from BSI and IE in 4 Italian hospitals, their antibiotic susceptibility—focusing on the emergence of hVISA—and genotypic relationships. Our results demonstrate that the epidemiology of MRSA is changing versus different STs possessing features between community-acquired (CA)- and hospital-acquired (HA)-MRSA groups; furthermore, different MSSA isolated from BSI and IE were found, with the same backgrounds of the Italian CA-MRSA. The hVISA phenotype was very frequent (19.5%) and occurred more frequently in isolates from IE and in both the MSSA and MRSA strains. As expected, hVISA were detected in MRSA with vancomycin minimum inhibitory concentrations (MICs) of 1–2 mg/l, frequently associated with the major SCCmec I and II nosocomial clones; this phenotype was also detected in some MSSA strains. The few cases of MR-hVISA infections evaluated in our study demonstrated that 5 out of 9 patients (55%) receiving a glycopeptide, died. Future studies are required to validate these findings in terms of clinical impact.

What is MRSA?

For decades methicillin-resistant Staphylococcus aureus (MRSA) has been considered the prototype of multi-resistant nosocomial pathogens, causing infections in high-risk patients. Changes in the healthcare system, coupled with the evolution of this versatile microorganism, have transformed MRSA into a cause of community-onset infections, in both patients who have contact with the healthcare system and patients without such a risk factor. New lineages of MRSA, defined as community acquired (CA)-MRSA, have emerged that have a propensity to cause infections in young individuals without risk factors. CA-MRSA primarily causes skin infections and, rarely, necrotising pneumonia. In the USA, these strains belong to a single widespread clone, designated USA300, while in Europe they belong to a variety of clones. Most strains carry genes for the Panton-Valentine leukocidin, whose role in diseases is under debate. In subjects living in the community who have contact with the healthcare system, MRSA strains of the nosocomial type are a frequent cause of infection and of pneumonia in particular. The detection of a large MRSA reservoir in pigs and the finding that professionally exposed individuals are colonised, has further shown that it is necessary to closely follow the epidemiology of MRSA if we want to combat it effectively.