Temporal changes in prevalence of antimicrobial resistance in 23 US hospitals

Methicillin-Resistant Staphylococcus aureus Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). MRSA pneumonia is associated with significant morbidity and mortality. Several virulence factors allow S. aureus to become an effective pathogen. The polysaccharide intracellular adhesin allows for the production of biofilms, some strains can produce capsular polysaccharides that protect against phagocytosis, microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) allow for colonization of epithelial surfaces, and S. aureus secretes several exotoxins that aid in tissue destruction. The α-hemolysin exotoxin secreted by S. aureus is one of the most important virulence factors for the bacteria. The diagnosis of MRSA pneumonia can be challenging; the infection may present as a mild respiratory infection or severe respiratory failure and septic shock. Many individuals are colonized with MRSA and thus a positive nasopharyngeal swab does not confirm infection in the lower respiratory tract. The management of MRSA pneumonia has evolved. Historically, vancomycin has been the primary antibiotic used to treat MRSA pneumonia. Over the past decade, prospective studies have shown that linezolid leads to higher rates of clinical cure. Monoclonal antibodies are being studied as potential therapeutic options. MRSA is an important cause of HAP/VAP; novel diagnostics may facilitate rapid diagnosis of this infection and the available literature should be used to make informed decisions on management.

Efficacy of Telavancin in Comparison to Linezolid in a Porcine Model of Severe Methicillin-Resistant Staphylococcus aureus Pneumonia

Current guidelines recommend vancomycin and linezolid as first-line agents against methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia. Telavancin is a potential new therapeutic alternative, specifically in monomicrobial MRSA pneumonia. This study compared the efficacies of telavancin versus linezolid in a porcine model of severe MRSA pneumonia. In 18 mechanically ventilated pigs (32.11 ± 1.18 kg), 75 ml of 10⁶ CFU/ml of MRSA was administered into each pulmonary lobe. After the onset of pneumonia, pigs were randomized into three groups: a control group, a group receiving 22.5 mg/kg of body weight every 24 h (q24h) of telavancin, and a group receiving 10 mg/kg q12h of linezolid intravenously. Tracheal aspirate and bronchoalveolar lavage (BAL) fluids were cultured every 24 h. After 48 h of treatment, tissue samples were collected from the ventral and dorsal sections of each lobe. Microbiological and histopathological analyses were performed. Lung tissue concentrations differed among the groups (P = 0.019), with the lowest MRSA lung burden in the telavancin group (P < 0.05 versus the control). MRSA was detected in 46.7%, 40.0%, and 21.7% of the lung tissue samples from the control, linezolid, and telavancin groups, respectively (P < 0.001). MRSA concentrations differed among the groups in tracheal aspirate fluid (P = 0.011) but not in BAL fluid. Furthermore, there was no increased risk of kidney injury during telavancin use. Thus, telavancin has higher bactericidal efficacy than linezolid during the first 48 h of treatment in a porcine model of severe MRSA pneumonia. However, studies are needed to confirm the benefits of telavancin in treating MRSA nosocomial pneumonia.

In vivo efficacy and pharmacokinetics of bi-aryl oxazolidinone RBx 11760 loaded polylactic acid-polyethylene glycol nanoparticles in mouse hematogenous bronchopneumonia and rat groin abscess caused by Staphylococcus aureus

RBx 11760 is a bi-aryl oxazolidinone antibacterial agent active against Staphylococcus aureus but has poor solubility. Here we have encapsulated RBx 11760 in PLA-PEG NPs with an aim to improve physicochemical, pharmacokinetics and in vivo efficacy. The average size and zeta potential of RBx 11760 loaded NPs were found to be 106.4 nm and -22.2 mV, respectively. The absolute size of nanoparticles by HRTEM was found to be approximately 80 nm. In vitro antibacterial agar well diffusion assay showed clear zone of inhibition of bacterial growth. In pharmacokinetic study, nanoparticle showed 4.6-fold and 7-fold increase in AUC_inf and half-life, respectively, as compared to free drug. RBx 11760 nanoparticle significantly reduced bacterial counts in lungs and improved the survival rate of immunocompromised mice as compared to free drugs. Thus, RBx 11760 loaded nanoparticles have strong potential to be used as nanomedicine against sensitive and drug resistant Staphylococcus aureus infections.

Bacterial clonal diagnostics as a tool for evidence-based empiric antibiotic selection

Despite the known clonal distribution of antibiotic resistance in many bacteria, empiric (pre-culture) antibiotic selection still relies heavily on species-level cumulative antibiograms, resulting in overuse of broad-spectrum agents and excessive antibiotic/pathogen mismatch. Urinary tract infections (UTIs), which account for a large share of antibiotic use, are caused predominantly by Escherichia coli, a highly clonal pathogen. In an observational clinical cohort study of urgent care patients with suspected UTI, we assessed the potential for E. coli clonal-level antibiograms to improve empiric antibiotic selection. A novel PCR-based clonotyping assay was applied to fresh urine samples to rapidly detect E. coli and the urine strain's clonotype. Based on a database of clonotype-specific antibiograms, the acceptability of various antibiotics for empiric therapy was inferred using a 20%, 10%, and 30% allowed resistance threshold. The test's performance characteristics and possible effects on prescribing were assessed. The rapid test identified E. coli clonotypes directly in patients' urine within 25-35 minutes, with high specificity and sensitivity compared to culture. Antibiotic selection based on a clonotype-specific antibiogram could reduce the relative likelihood of antibiotic/pathogen mismatch by ≥ 60%. Compared to observed prescribing patterns, clonal diagnostics-guided antibiotic selection could safely double the use of trimethoprim/sulfamethoxazole and minimize fluoroquinolone use. In summary, a rapid clonotyping test showed promise for improving empiric antibiotic prescribing for E. coli UTI, including reversing preferential use of fluoroquinolones over trimethoprim/sulfamethoxazole. The clonal diagnostics approach merges epidemiologic surveillance, antimicrobial stewardship, and molecular diagnostics to bring evidence-based medicine directly to the point of care.

Adverse Outcomes From Hospital-Acquired Infection in Pennsylvania Cannot Be Attributed to Increased Risk on Admission

In July 2005, Pennsylvania became the first state in the nation to publicly report statewide data on hospital-acquired infections (HAI). The published research brief revealed that 11 668 hospitalizations with HAI had markedly different mortality rates, lengths of stay (LOS), and charges than cases without HAI did. To avoid a possibly biased comparison, a 5 to 1 propensity-matched cohort study was performed. Nine cohorts (ie, heart failure, chronic obstructive pulmonary disease, respiratory failure, pneumonia, hip fracture, major surgical complications, colonic resection, diabetes, and gastrointestinal bleeding) were examined for differences in mortality, LOS, and hospital charges. Statistically significant increases in mortality, LOS, and charges were found among HAI cases. HAI cases had more than a 4 times higher median charge than nonHAI controls did. Observed differences in mortality, LOS, and charges between HAI and non-HAI cases in Pennsylvania cannot be explained on the basis of increased disease-specific severity at the time of admission.

Methicillin-ResistantStaphylococcus aureusin German Intensive Care Units During 2000-2003: Data from Project SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units)

Objectives.

The objective of this study was to analyze methicillin-resistantStaphylococcus aureus(MRSA) percentages (defined as the percentage ofS. aureusisolates that are resistant to methicillin) and antimicrobial consumption in intensive care units (ICUs) participating in Project SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units), to look for temporal changes in MRSA percentages and antimicrobial consumption in individual ICUs as an indicator of the impact of an active surveillance system, and to investigate the differences between ICUs with increased MRSA percentages versus those with decreased percentages during a period of 3 years (2001-2003).

Methods.

This was a prospective, ICU-based and laboratory-based surveillance study involving 38 German ICUs during 2000-2003. Antimicrobial use was reported in terms of defined daily doses (DDDs) per 1,000 patient-days. Temporal changes in the MRSA percentage and antimicrobial use in individual ICUs were calculated by means of the Wilcoxon signed rank test. The incidence density of nosocomial MRSA infection was defined as the number of nosocomial MRSA infections per 1,000 patient-days.

Results.

From February 2000 through December 2003, a total of 38 ICUs reported data on 499,694 patient-days and 9,552S. aureusisolates, including 2,249 MRSA isolates and 660,029 DDDs of antimicrobials. Cumulative MRSA percentages ranged from 0% to 64.4%, with a mean of 23.6%. The MRSA incidence density ranged from 0 to 38.2 isolates per 1,000 patient-days, with a mean of 2.77 isolates per 1,000 patient-days. There was a positive correlation between MRSA percentage and imipenem and ciprofloxacin use (P<.05). Overall, comparison of data from 2001 with data from 2003 showed that MRSA percentages increased in 18 ICUs (median increase, 13.2% [range, 1.6%-38.4%]) and decreased in 14 ICUs (median decrease, 12% [range, 1.0%-48.4%]). Increased use of third-generation cephalosporins, glycopeptides, or aminoglycosides correlated significantly with an increase in the MRSA percentage (P<.05). The cumulative nosocomial MRSA infection incidence density for 141 ICUs that did not participate in SARI and, therefore, did not receive feedback increased from 0.26 to 0.35 infections per 1,000 patient-days during a 3-year period, whereas the rate in SARI ICUs decreased from 0.63 to 0.40 infections per 1,000 patient-days.

Conclusion.

The MRSA situation in German ICUs is still heterogeneous. Because MRSA percentages range from 0% to 64.4%, further studies are required to confirm findings that no change in the MRSA percentage and a decrease in the nosocomial MRSA infection incidence density in SARI ICUs reflect the impact of an active surveillance system.

Gloves, gowns and masks for reducing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in the hospital setting

BACKGROUND

Meticillin-resistant Staphylococcus aureus (MRSA; also known as methicillin-resistant S aureus) is a common hospital-acquired pathogen that increases morbidity, mortality, and healthcare costs. Its control continues to be an unresolved issue in many hospitals worldwide. The evidence base for the effects of the use of gloves, gowns or masks as control measures for MRSA is unclear.

OBJECTIVES

To assess the effectiveness of wearing gloves, a gown or a mask when contact is anticipated with a hospitalised patient colonised or infected with MRSA, or with the patient's immediate environment.

SEARCH METHODS

We searched the Specialised Registers of three Cochrane Groups (Wounds Group on 5 June 2015; Effective Practice and Organisation of Care (EPOC) Group on 9 July 2013; and Infectious Diseases Group on 5 January 2009); CENTRAL (The Cochrane Library 2015, Issue 6); DARE, HTA, NHS EED, and the Methodology Register (The Cochrane Library 2015, Issue 6); MEDLINE and MEDLINE In-Process & Other Non-Indexed Citations (1946 to June week 1 2015); EMBASE (1974 to 4 June 2015); Web of Science (WOS) Core Collection (from inception to 7 June 2015); CINAHL (1982 to 5 June 2015); British Nursing Index (1985 to 6 July 2010); and ProQuest Dissertations & Theses Database (1639 to 11 June 2015). We also searched three trials registers (on 6 June 2015), references list of articles, and conference proceedings. We finally contacted relevant individuals for additional studies.

SELECTION CRITERIA

Studies assessing the effects on MRSA transmission of the use of gloves, gowns or masks by any person in the hospital setting when contact is anticipated with a hospitalised patient colonised or infected with MRSA, or with the patient's immediate environment. We did not assess adverse effects or economic issues associated with these interventions.We considered any comparator to be eligible. With regard to study design, only randomised controlled trials (clustered or not) and the following non-randomised experimental studies were eligible: quasi-randomised controlled trials (clustered or not), non-randomised controlled trials (clustered or not), controlled before-and-after studies, controlled cohort before-after studies, interrupted time series studies (controlled or not), and repeated measures studies. We did not exclude any study on the basis of language or date of publication.

DATA COLLECTION AND ANALYSIS

Two review authors independently decided on eligibility of the studies. Had any study having been included, two review authors would have extracted data (at least for outcome data) and assessed the risk of bias independently. We would have followed the standard methodological procedures suggested by Cochrane and the Cochrane EPOC Group for assessing risk of bias and analysing the data.

MAIN RESULTS

We identified no eligible studies for this review, either completed or ongoing.

AUTHORS' CONCLUSIONS

We found no studies assessing the effects of wearing gloves, gowns or masks for contact with MRSA hospitalised patients, or with their immediate environment, on the transmission of MRSA to patients, hospital staff, patients' caregivers or visitors. This absence of evidence should not be interpreted as evidence of no effect for these interventions. The effects of gloves, gowns and masks in these circumstances have yet to be determined by rigorous experimental studies, such as cluster-randomised trials involving multiple wards or hospitals, or interrupted time series studies.

Occurrence of Co-colonization or Co-Infection with Vancomycin-Resistant Enterococci and Methicillin-ResistantStaphylococcus aureusin a Medical Intensive Care Unit

Objective:

To determine the occurrence of co-colonization or co-infection with VRE and MRSA among medical patients requiring intensive care.

Design:

Prospective, single-center, observational study.

Setting:

A 19-bed medical ICU in an urban teaching hospital.

Patients:

Adult patients requiring at least 48 hours of intensive care and having at least one culture performed for microbiologie evaluation.

Results:

Eight hundred seventy-eight consecutive patients were evaluated. Of these patients, 402 (45.8%) did not have microbiologie evidence of colonization or infection with either VRE or MRSA 355 (40.4%) were colonized or infected with VRE, 38 (4.3%) were colonized or infected with MRSA, and 83 (9.5%) had co-colonization or co-infection with VRE and MRSA. Multiple logistic regression analysis demonstrated that increasing age, hospitalization during the preceding 6 months, and admission to a long-term-care facility were independently associated with colonization or infection due to VRE and co-colonization or co-infection with VRE and MRSA. The distributions of positive culture sites for VRE (stool, 86.7%; blood, 6.5%; urine, 4.8%; soft tissue or wound, 2.0%) and for MRSA (respiratory secretions, 34.1%; blood, 32.6%; urine, 17.1%; soft tissue or wound, 16.2%) were statistically different (P< .001).

Conclusions:

Co-colonization or co-infection with VRE and MRSA is common among medical patients requiring intensive care. The recent emergence of vancomycin-resistantStaphylococcus aureusand the presence of a patient population co-colonized or co-infected with VRE and MRSA support the need for aggressive infection control measures in the ICU.

Increase in the Prevalence of Carbapenem-Resistant Acinetobacter Isolates and Ampicillin-Resistant Non-Typhoidal Salmonella Species in Korea: A KONSAR Study Conducted in 2011

Background

Antimicrobial surveillance is important for providing an up-to-date understanding of the epidemiology of antimicrobial resistance and for creating a forum for rational drug development. In this study, we analyzed antimicrobial test data generated in 2011 by hospitals and commercial laboratories participating in the Korean Nationwide Surveillance of Antimicrobial Resistance program (KONSAR).

Materials and Methods

Data on the results of susceptibility tests conducted in 32 hospitals and two commercial laboratories were analyzed. Data on isolates from patients admitted to an intensive care unit (ICU) and those admitted to other wards were compared. Intermediate susceptibility was not analyzed and duplicate isolates were excluded.

Results

Escherichia coli was the most prevalent organism identified in both the hospital and commercial laboratories. Among the hospital isolates, methicillin-resistant Staphylococcus aureus (MRSA), penicillin G-non-susceptible Streptococcus pneumoniae, and ampicillin-resistant Enterococcus faecium remained as prevalent as they were in 2009. The proportion of vancomycin-resistant E. faecium (VR-EFM) slightly decreased from 29% in 2009 to 23% in 2011. Resistance rates of Klebsiella pneumoniae to ceftazidime, cefoxitin, fluoroquinolone, and amikacin were 24%, 14%, 27%, and 8%, respectively. Resistance rates of Pseudomonas aeruginosa to fluoroquinolone, ceftazidime, imipenem, and amikacin were 33%, 20%, 22%, and 16%, respectively, whereas those of Acinetobacter spp. resistance were 71%, 66%, 64, and 51%, respectively. The prevalence of oxyimino-cephalosporin-resistant E. coli and K. pneumoniae, carbapenem-resistant Acinetobacter spp. and P. aeruginosa, MRSA, and VR-EFM among ICU isolates was higher than those among non-ICU isolates. Extended-spectrum β-lactamase-producing E. coli and K. pneumoniae, imipenem-resistant P. aeruginosa, and VR-EFM were more prevalent among isolates from commercial laboratories than those from hospitals. Resistance rates of K. pneumoniae to ceftazidime and amikacin decreased from 32% and 24% in 2005 to 24% and 8% in 2011, respectively. The resistance rate of P. aeruginosa to amikacin decreased from 22% in 2005 to 16% in 2011. The proportion of imipenem-resistant Acinetobacter spp. increased from 16% in 2005 to 64% in 2011.

Conclusions

The prevalence of MRSA, penicillin G-non-susceptible S. pneumoniae, and ampicillin-resistant E. faecium among clinical isolates tested in laboratories remained high. Multidrug resistance was more prevalent among isolates from ICUs. The prevalence of ceftazidime-resistant and amikacin-resistant K. pneumoniae and amikacin-resistant P. aeruginosa decreased after 2005, while the prevalence of imipenem-resistant Acinetobacter spp. increased.

Antimicrobial resistance and molecular epidemiology of Staphylococcus aureus from Ulaanbaatar, Mongolia

This study aimed to characterize Staphylococcus aureus (S. aureus) strains isolated from human infections in Mongolia. Infection samples were collected at two time periods (2007–08 and 2011) by the National Center for Communicable Diseases (NCCD) in Ulaanbaatar, Mongolia. S. aureus isolates were characterized using polymerase chain reaction (PCR) for mecA, PVL, and sasX genes and tested for agr functionality. All isolates were also spa typed. A subset of isolates selected by frequency of spa types was subjected to antimicrobial susceptibility testing and multilocus sequence typing. Among 251 S. aureus isolates, genotyping demonstrated methicillin resistance in 8.8% of isolates (22/251). Approximately 28% of the tested S. aureus isolates were observed to be multidrug resistant (MDR). Sequence type (ST) 154 (spa t667) was observed to be a strain with high virulence potential, as all isolates for this spa type were positive for PVL, had a functional agr system and 78% were MDR. S. aureus isolates of ST239 (spa t037) were observed to cause infections and roughly 60% had functional agr system with a greater proportion being MDR. Additionally, new multilocus sequence types and new spa types were identified, warranting continued surveillance for S. aureus in this region.

Linezolid versus vancomycin or teicoplanin for nosocomial pneumonia: meta-analysis of randomised controlled trials

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial pneumonia. Compared with glycopeptide antibiotics, linezolid achieves higher lung epithelial lining fluid concentrations, which may have an advantage in treating nosocomial pneumonia patients. The objective of this study was to evaluate the efficacy and safety of linezolid versus vancomycin or teicoplanin for the treatment of nosocomial pneumonia. Data were obtained from the Cochrane Central Register of Controlled Trials and the EMBASE and MEDLINE databases. Randomised controlled studies involving the use of linezolid versus vancomycin or teicoplanin in nosocomial pneumonia patients were included in the study. Twelve linezolid trials were included. There was no statistically significant difference between the two groups in the treatment of nosocomial pneumonia regarding the clinical cure rate [relative risk (RR) = 1.08, 95 % confidence interval (CI) = 1.00-1.17, p = 0.06]. Linezolid was associated with better microbiological eradication rate in nosocomial pneumonia patients compared with glycopeptide antibiotics (RR = 1.16, 95 % CI = 1.03-1.31, p = 0.01). There were no differences in the all-cause mortality (RR = 0.95, 95 % CI = 0.83-1.09, p = 0.46) between the two groups. However, the risks of rash (RR = 0.41, 95 % CI = 0.24-0.71, p = 0.001) and renal dysfunction (RR = 0.41, 95 % CI = 0.27-0.64, p < 0.0001) were higher with glycopeptide antibiotics. Although linezolid was more effective in eradicating microbiology than glycopeptide antibiotics for nosocomial pneumonia patients, it did not demonstrate superiority in clinical cure. The incidences of renal dysfunction and rash are higher in the glycopeptide antibiotics group.

Improved outcome of ventilator-associated pneumonia caused by methicillin-resistant Staphylococcus aureus in a trauma population

BACKGROUND

The treatment of ventilator-associated pneumonia (VAP) secondary to methicillin-resistant Staphylococcus aureus (MRSA) remains controversial.

METHODS

We performed a review of all blunt trauma patients diagnosed with MRSA VAP from June 2005 to June 2011. VAP for the first 3 years was diagnosed by sputum aspiration and treated with vancomycin. For the last 3 years of the study period, VAP was diagnosed with bronchoalveolar lavage and treated with linezolid.

RESULTS

MRSA VAP patients treated with vancomycin had an average hospital length of stay (LOS) of 49 days (range 9-99 days), an average intensive care unit (ICU) LOS of 43 days (range 6-98 days), and average ventilator days of 34.4 (range 3-76 days). Seventeen MRSA VAP patients treated with linezolid had an average hospital LOS of 27 days (range 11-61), an average ICU LOS of 22 days (range 10-42) days, and average ventilator days of 16.6 (range 2-42).

CONCLUSIONS

Trauma patients who develop MRSA VAP appear to have fewer ventilator days and shorter ICU and hospital LOS when treated with linezolid.

Trends in aminoglycoside use and gentamicin-resistant gram-negative clinical isolates in US academic medical centers: implications for antimicrobial stewardship

OBJECTIVE

To measure trends in aminoglycoside antibiotic use and gentamicin-resistant clinical isolates across a network of hospitals and compare network-level relationships with those of individual hospitals.

DESIGN

Longitudinal observational investigation.

SETTING

US academic medical centers.

PARTICIPANTS

Adult inpatients.

METHODS

Adult aminoglycoside use was measured from 2002 or 2003 through 2009 in 29 hospitals. Hospital-wide antibiograms assessed gentamicin resistance by proportions and incidence rates for Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. Mixed-effects analysis of variance was used to assess the significance of changes in aminoglycoside use and changes in resistance rates and proportions. Generalized estimating equations were used to assess the relationship between aminoglycoside use and resistance.

RESULTS

Mean aminoglycoside use declined by 41%, reflecting reduced gentamicin (P < .0001) and tobramycin (P < .005) use; amikacin use did not change. The rate and proportion of gentamicin-resistant P. aeruginosa decreased by 48% (P < .0001) and 31% (P < .0001), respectively. The rate and proportion of gentamicin-resistant E. coli increased by 166% and 124%, respectively (P < .0001), and they were related to increasing quinolone resistance in E. coli. Resistance among K. pneumoniae and A. baumannii did not change. Relationships between aminoglycoside use and resistance at the network level were highly variable at the individual hospital level.

CONCLUSIONS

Mean aminoglycoside use declined in this network of US hospitals and was associated with significant and opposite changes in rates of resistance for some organisms and no change for others. At the individual hospital level, antibiograms appear to be an unreliable reflection of antibiotic use, at least for aminoglycosides.

Infections caused by multidrug resistant organisms are not associated with overall, all-cause mortality in the surgical intensive care unit: the 20,000 foot view

BACKGROUND

Resistant pathogens are increasingly common in the ICU, with controversy regarding their relationship to outcomes. We hypothesized that an increasing number of infections with resistant pathogens in our surgical ICU would not be associated with increased overall mortality.

STUDY DESIGN

All ICU-acquired infections were prospectively identified between January 1, 2000 and December 31, 2009 in a single surgical ICU. Crude in-hospital, all-cause mortality data were obtained using a prospectively collected ICU database. Trends in rates were compared using linear regression.

RESULTS

A total of 799 resistant pathogens were identified (257 gram-positive, 542 gram-negative) from a total of 3,024 isolated pathogens associated with 2,439 ICU-acquired infections. The most frequently identified resistant gram-positive and -negative pathogens (defined as resistant to at least 1 major class of antimicrobials) were methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Pathogens were most commonly isolated from the lung, blood, and urine. The crude mortality rate declined steadily from 2000 to 2009 (9.4% to 5.4%; equation for trend y = -0.11x + 8.26). Linear regression analysis of quarterly rates revealed a significant divergence in trends between increasing total resistant infections (equation for trend y = 0.34x + 13.02) and percentage resistant infections (equation for trend y = 0.36x + 18.66) when compared with a decreasing mortality (p = 0.0003, p < 0.0001, respectively).

CONCLUSIONS

Despite a steady rise in the proportion of resistant bacterial infections in the ICU, crude mortality rates have decreased over time. The rates of resistant infections do not appear to be a significant factor in overall mortality in our surgical ICU patients.

Ventilator-associated pneumonia due to meticillin-resistant Staphylococcus aureus: risk factors and outcome in a large general hospital

BACKGROUND

Data about risk factors and impact on outcome of methicillin-resistant S. aureus (MRSA) in unselected patients with ventilator-associated pneumonia (VAP) are limited.

AIM

To assess predisposing factors and outcome of VAP due to MRSA in a large teaching institution.

METHODS

Prospective study carried out over four years in the three adult ICUs of our hospital. Patients with MRSA-VAP were compared with those with bacterial VAP due to other microorganisms.

FINDINGS

Overall, 474 episodes of bacterial VAP were collected. Significant differences between MRSA-VAP (111) and VAP due to other microorganisms (363) were found for median age (68 vs. 62 years), median APACHE II score (12 vs. 11), neurosurgery (5.4% vs. 13.8%), abdominal surgery (35% vs. 19%), prior treatment with any antibiotic (82.9% vs. 64.5%) and with imipenem (24% vs. 11%) at present admission before VAP, and pleural effusion (12% vs. 5%). Multivariate analysis adjusted for confounding factors showed that higher APACHE II score, prior treatment with any antibiotic and pleural effusion were independent risk factors for MRSA. As for treatment and outcome, the differences between MRSA-VAP and other VAP were inadequate empiric treatment (70% vs. 53%), median cost of antibiotics per episode (€974 vs. €726), and in-hospital mortality (60% vs. 47%). At multivariate analysis, however, MRSA was not found to be an independent risk factor for mortality.

CONCLUSION

MRSA is a common cause of VAP. Underlying conditions predispose to its high mortality.

Further increases in carbapenem-, amikacin-, and fluoroquinolone-resistant isolates of Acinetobacter spp. and P. aeruginosa in Korea: KONSAR study 2009

PURPOSE

The increasing prevalence of antimicrobial resistant bacteria has become a serious worldwide problem. The aim of this study was to analyze antimicrobial resistance data generated in 2009 by hospitals and commercial laboratories participating in the Korean Nationwide Surveillance of Antimicrobial Resistance program.

MATERIALS AND METHODS

Susceptibility data were collected from 24 hospitals and two commercial laboratories. In the analysis, resistance did not include intermediate susceptibility. Duplicate isolates were excluded from the analysis of hospital isolates, but not from the commercial laboratory isolates.

RESULTS

Among the hospital isolates, methicillin-resistant Staphylococcus aureus, penicillin G-nonsusceptible Streptococcus pneumoniae based on meningitis breakpoint, and ampicillin- resistant Enterococcus faecium remained highly prevalent. The proportion of vancomycin-resistant E. faecium gradually increased to 29%. Ceftazidime-resistant Escherichia coli and Klebsiella pneumoniae increased to 17% and 33%, respectively, and fluoroquinolone-resistant K. pneumoniae, Acinetobacter spp. and Pseudomonas aeruginosa increased to 33%, 67% and 39%, respectively. Amikacin-resistant Acinetobacter spp. increased to 48%. Imipenem-resistant Acinetobacter spp. and P. aeruginosa increased to 51% and 26%, respectively. Higher resistance rates were observed in intensive care unit (ICU) isolates than in non-ICU isolates among the isolates from hospitals. Resistance rates were higher in hospital isolates than in clinic isolates among the isolates from commercial laboratories.

CONCLUSION

Among the hospital isolates, ceftazidime-resistant K. pneumoniae and fluoroquinolone- resistant K. pneumoniae, Acinetobacter spp., and P. aeruginosa further increased. The increase in imipenem resistance was slight in P. aeruginosa, but drastic in Acinetobacter spp. The problematic antimicrobial-organism combinations were much more prevalent among ICU isolates.

Increase of ceftazidime- and fluoroquinolone-resistant Klebsiella pneumoniae and imipenem-resistant Acinetobacter spp. in Korea: analysis of KONSAR study data from 2005 and 2007

PURPOSE

Antimicrobial resistance monitoring could be a useful source of information for treating and controlling nosocomial infections. We analyzed antimicrobial resistance data generated by Korean Hospitals and by a commercial laboratory in 2005 and 2007.

MATERIALS AND METHODS

Susceptibility data for 2005 and 2007 were collected from 37 and 41 hospitals, respectively, and from one commercial laboratory. Intermediate susceptibility was not included in the calculation of resistance rates.

RESULTS

Methicillin-resistant Staphylococcus aureus (MRSA) (64%), third-generation cephalosporin-resistant Klebsiella pneumoniae (29%), fluoroquinolone-resistant Escherichia coli (27%), Pseudomonas aeruginosa (33%), and Acinetobacter spp. (48%), and amikacin-resistant P. aeruginosa (19%) and Acinetobacter spp. (37%) were prevalent in hospitals in 2007. A gradual increase of vancomycin-resistant Enterococcus faecium and imipenem-resistant Acinetobacter spp. was observed. Higher incidences of thirdgeneration cephalosporin-resistant E. coli and K. pneumoniae and imipenemresistant P. aeruginosa were found in the commercial laboratory than in the hospitals.

CONCLUSION

Methicillin-resistant S. aureus, third-generation cephalosporin- resistant K. pneumoniae, and fluoroquinolone-resistant E. coli, P. aeruginosa and Acinetobacter spp. remain prevalent in Korea, while the incidence of vancomycin-resistant E. faecium and imipenem-resistant Acinetobacter spp. has increased gradually. The higher prevalences of third-generation cephalosporinresistant E. coli and K. pneumoniae, and imipenem-resistant P. aeruginosa in the commercial laboratory are a new concern.

Methicillin-resistant Staphylococcus aureus: the superbug

Over the last decade, methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged as serious pathogens in the nosocomial and community setting. Hospitalization costs associated with MRSA infections are substantially greater than those associated with methicillin-sensitive S. aureus (MSSA) infections, and MRSA has wider economic effects that involve indirect costs to the patient and to society. In addition, there is some evidence suggesting that MRSA infections increase morbidity and the risk of mortality. Glycopeptides are the backbone antibiotics for the treatment of MRSA infections. However, several recent reports have highlighted the limitations of vancomycin, and its role in the management of serious infections is now being reconsidered. Several new antimicrobials demonstrate in vitro activity against MRSA and other Gram-positive bacteria. Data from large surveys indicate that linezolid, daptomycin, and tigecycline are almost universally active against MRSA. This review will briefly discuss the epidemiology, costs, outcome, and therapeutic options for the management of MRSA infections.

Impact of an antimicrobial utilization program on antimicrobial use at a large teaching hospital: a randomized controlled trial

BACKGROUND

Multidisciplinary antimicrobial utilization teams (AUTs) have been proposed as a mechanism for improving antimicrobial use, but data on their efficacy remain limited.

OBJECTIVE

To determine the impact of an AUT on antimicrobial use at a teaching hospital.

DESIGN

Randomized controlled intervention trial.

SETTING

A 953-bed, public, university-affiliated, urban teaching hospital.

PATIENTS

Patients who were given selected antimicrobial agents (piperacillin-tazobactam, levofloxacin, or vancomycin) by internal medicine ward teams.

INTERVENTION

Twelve internal medicine teams were randomly assigned monthly: 6 teams to an intervention group (academic detailing by the AUT) and 6 teams to a control group that was given indication-based guidelines for prescription of broad-spectrum antimicrobials (standard of care), during a 10-month study period.

MEASUREMENTS

Proportion of appropriate empirical, definitive (therapeutic), and end (overall) antimicrobial usage.

RESULTS

A total of 784 new prescriptions of piperacillin-tazobactam, levofloxacin, and vancomycin were reviewed. The proportion of antimicrobial prescriptions written by the intervention teams that was considered to be appropriate was significantly higher than the proportion of antimicrobial prescriptions written by the control teams that was considered to be appropriate: 82% versus 73% for empirical (risk ratio [RR], 1.14; 95% confidence interval [CI], 1.04-1.24), 82% versus 43% for definitive (RR, 1.89; 95% CI, 1.53-2.33), and 94% versus 70% for end antimicrobial usage (RR, 1.34; 95% CI, 1.25-1.43). In multivariate analysis, teams that received feedback from the AUT alone (adjusted RR, 1.37; 95% CI, 1.27-1.48) or from both the AUT and the infectious diseases consultation service (adjusted RR, 2.28; 95% CI, 1.64-3.19) were significantly more likely to prescribe end antimicrobial usage appropriately, compared with control teams.

CONCLUSIONS

A multidisciplinary AUT that provides feedback to prescribing physicians was an effective method in improving antimicrobial use. Trial registration. ClinicalTrials.gov identifier: NCT00552838.

Are there differences in hospital cost between patients with nosocomial methicillin-resistant Staphylococcus aureus bloodstream infection and those with methicillin-susceptible S. aureus bloodstream infection?

OBJECTIVE

To examine the impact of methicillin resistance on in-hospital mortality, length of stay, and hospital cost after the onset of nosocomial Staphylococcus aureus bloodstream infection (BSI).

DESIGN

A retrospective cohort study.

SETTING

A tertiary care hospital in Rhode Island.

PATIENTS

A cohort of 182 consecutive patients who developed nosocomial BSI due to methicillin-susceptible and methicillin-resistant S. aureus (MSSA and MRSA, respectively)

RESULTS

Patients with MRSA BSI had a significantly longer total length of hospital and intensive care unit (ICU) stay before the onset of BSI and a higher average daily cost. Compared with ICU patients with MSSA BSI, those with MRSA BSI had a higher median total hospital cost ($42,137 vs $113,852), higher hospital cost after infection ($17,603 vs $51,492), and greater length of stay after infection (10.5 vs 20.5 days). After multivariable adjustment, ICU patients with MRSA BSI had significantly increased total hospital cost, hospital cost after infection, and length of stay after infection. However, using a propensity score approach, we found that, among ICU patients, the difference in cost after infection and the difference in length of stay after infection for MRSA, compared with MSSA BSI, were not significant. The differences among non-ICU patients who developed MRSA or MSSA BSI were not significant after multivariable adjustment or by propensity score.

CONCLUSIONS

On the basis of propensity score, we found that methicillin resistance did not independently increase hospital cost or length of stay after onset of S. aureus BSI. We believe that use of a propensity score on a comparable subset of patients may be a better method than multivariable adjustment for assessing the impact of methicillin resistance in cohort studies.

Methicillin resistant Staphylococcus aureus (MRSA) prevention through facility-wide culture change

Hospitals across the United States and around the world are fighting the escalation of drug-resistant infections. In response to this costly and life-threatening problem, facilities are engaging in vigorous programs to prevent its occurrence and spread. This article presents one hospital's fight against methicillin-resistant Staphylococcus aureus by implementing a facility-wide program aimed at changing and standardizing the culture within the hospital.

Urinary Tract Infections in Extended Care Facilities: Preventive Management Strategies

OBJECTIVE

To provide health care professionals with an overview of interventions that may be done to reduce the incidence of urinary tract infections (UTIs) in elderly patients, especially those residing in extended care facilities.

DATA SOURCES

A Medline search of the English literature was performed from 1980 to January 2006 to find literature relevant to urinary tract prophylaxis. Further references were hand-searched from relevant sources.

STUDY SELECTION

When assessing the effectiveness of various clinical interventions for reducing the incidence of UTIs in the elderly, preference was given to more recent, double-blind, placebo-controlled randomized studies, but studies of less robust design also were included in the discussions when the former were lacking.

DATA EXTRACTION

Where possible, recent publications were favored over older studies. References were all reviewed by the authors and chosen to present key citations.

DATA SYNTHESIS

Data selection was prioritized to address specific subtopics.

CONCLUSION

Though still frequent in occurrence and quite costly in terms of morbidity, mortality, and cost to the health care system, numerous measures may be taken to ameliorate the incidence of UTIs in elderly, institutionalized residents. First and foremost, establishing and adhering to good infection-control practices by health care givers and minimizing the use of indwelling catheters are essential. Adequate staffing and training are germane to this effort. Reasonably well-designed clinical studies also give credence to the use of topical estrogens and lactobacillus "probiotics" for female subgroups and cranberry juice for a wider array of patients. Vitamin C is of no proven benefit. With regard to antibiotics, with the relative paucity of data available for this patient population, concerns for resistance proliferation must be balanced against perceived gains in UTI reduction.

Mupirocin resistance among methicillin-resistant Staphylococcus aureus-colonized patients at admission to a tertiary care medical center

All patients admitted to our tertiary care hospital from 1 December 2007 to 10 June 2008 were screened for methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) nasal colonization, and the isolates were tested for mupirocin susceptibility by using Etest. Mupirocin resistance (MR) was noted to occur in 3.4% of MRSA carriers, and high-level MR was noted to occur in 0.62% of carriers.

NHSN annual update: antimicrobial-resistant pathogens associated with healthcare-associated infections: annual summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2006-2007

OBJECTIVE

To describe the frequency of selected antimicrobial resistance patterns among pathogens causing device-associated and procedure-associated healthcare-associated infections (HAIs) reported by hospitals in the National Healthcare Safety Network (NHSN).

METHODS

Data are included on HAIs (ie, central line-associated bloodstream infections, catheter-associated urinary tract infections, ventilator-associated pneumonia, and surgical site infections) reported to the Patient Safety Component of the NHSN between January 2006 and October 2007. The results of antimicrobial susceptibility testing of up to 3 pathogenic isolates per HAI by a hospital were evaluated to define antimicrobial-resistance in the pathogenic isolates. The pooled mean proportions of pathogenic isolates interpreted as resistant to selected antimicrobial agents were calculated by type of HAI and overall. The incidence rates of specific device-associated infections were calculated for selected antimicrobial-resistant pathogens according to type of patient care area; the variability in the reported rates is described.

RESULTS

Overall, 463 hospitals reported 1 or more HAIs: 412 (89%) were general acute care hospitals, and 309 (67%) had 200-1,000 beds. There were 28,502 HAIs reported among 25,384 patients. The 10 most common pathogens (accounting for 84% of any HAIs) were coagulase-negative staphylococci (15%), Staphylococcus aureus (15%), Enterococcus species (12%), Candida species (11%), Escherichia coli (10%), Pseudomonas aeruginosa (8%), Klebsiella pneumoniae (6%), Enterobacter species (5%), Acinetobacter baumannii (3%), and Klebsiella oxytoca (2%). The pooled mean proportion of pathogenic isolates resistant to antimicrobial agents varied significantly across types of HAI for some pathogen-antimicrobial combinations. As many as 16% of all HAIs were associated with the following multidrug-resistant pathogens: methicillin-resistant S. aureus (8% of HAIs), vancomycin-resistant Enterococcus faecium (4%), carbapenem-resistant P. aeruginosa (2%), extended-spectrum cephalosporin-resistant K. pneumoniae (1%), extended-spectrum cephalosporin-resistant E. coli (0.5%), and carbapenem-resistant A. baumannii, K. pneumoniae, K. oxytoca, and E. coli (0.5%). Nationwide, the majority of units reported no HAIs due to these antimicrobial-resistant pathogens.

The Utility of Fluoroquinolones in the Critically Ill

Fluoroquinolone antibiotics have been used for more than 40 years to treat a variety of infections from simple uncomplicated urinary tract infections to infections as severe as nosocomial-acquired pneumonia. Their availability both orally and intravenously, ease of dosing, favorable safety profile, and broad spectrum of activity have led to the pervasive use of these agents in both the community and institutions. Unfortunately, this widespread use has led to the development of resistance and subsequently, increased mortality. Resistance, specifically with Pseudomonas aeruginosa and Escherichia coli, as well as their association with the development of Clostridium difficile–associated diarrhea, has led many clinicians to question the use of fluoroquinolones in the critically ill. This article will review these issues related to the use of fluoroquinolones, in an effort to better define their role among institutionalized patients.

5 Million Lives Campaign. Case study: an MRSA intervention at Evanston Northwestern Healthcare

PCR-based testing offers superiority to culture in reduction of unisolated days. The ICU-based surveillance intervention had little impact after one year with surveillance compliance at 67%. However, once compliance improved, surveillance was expanded to the entire hospital and decolonization was implemented, MRSA BSIs were significantly reduced. Our experience parallels that of the European countries and other United States facilities that have implemented aggressive MRSA control measures. All successful programs have included active surveillance testing and barrier precautions. Finally, according to the Centers for Disease Control and Prevention's just-released report on invasive MRSA, since most MRSA infections are associated with health care contact, strategies to prevent and control MRSA among inpatients still may have a positive impact on infection, as demonstrated by our intervention.

Structure and thermotropic behavior of the Staphylococcus aureus lipid lysyl-dipalmitoylphosphatidylglycerol

We have characterized the structural and thermotropic properties of one of the most important lipids in the cell membrane of Staphylococcus aureus, lysyl-dipalmitoylphosphatidylglycerol (lysyl-DPPG). applying differential scanning calorimetry and small- and wide-angle x-ray scattering. Microcalorimetry revealed that under physiological conditions (phosphate buffer, 20 mM NaPi, 130 mM NaCl, pH 7.4), the synthetic lysyl-DPPG resembles the features of the parent dipalmitoylphosphatidylglycerol (DPPG) with respect to its melting behavior. However, in contrast to DPPG, lowering the pH did not significantly affect the main transition temperature ( approximately 40 degrees C) of lysyl-DPPG, which can be explained by its difference in protonization because of the lysine group. X-ray experiments yielded the first information on chain packing and morphology of lysyl-DPPG. We found that lysyl-DPPG forms an interdigitated lamellar phase below the chain-melting transition. This can be explained by the large headgroup area of lysyl-DPPG as a result of its charged lysine group, especially if the headgroup is arranged parallel to the bilayer plane. Additionally, lysyl-DPPG degradation products, such as lysine and free fatty acids, had significant influences on the melting behavior and led to a multicomponent melting transition. Our results indicate that the degradation of lysyl-DPPG takes place mainly during the hydration process but also depends on lipid storage time, pH, and thermal treatment. Detailed temperature-resolved experiments at pH 5.0 demonstrated the formation of a lamellar gel phase with tilted hydrocarbon chains and a ripple phase, coexisting with the interdigitated lysyl-DPPG bilayers.

Antimicrobial resistance among Gram-negative bacilli causing infections in intensive care unit patients in the United States between 1993 and 2004

During the 12-year period from 1993 to 2004, antimicrobial susceptibility profiles of 74,394 gram-negative bacillus isolates recovered from intensive care unit (ICU) patients in United States hospitals were determined by participating hospitals and collected in a central location. MICs for 12 different agents were determined using a standardized broth microdilution method. The 11 organisms most frequently isolated were Pseudomonas aeruginosa (22.2%), Escherichia coli (18.8%), Klebsiella pneumoniae (14.2%), Enterobacter cloacae (9.1%), Acinetobacter spp. (6.2%), Serratia marcescens (5.5%), Enterobacter aerogenes (4.4%), Stenotrophomonas maltophilia (4.3%), Proteus mirabilis (4.0%), Klebsiella oxytoca (2.7%), and Citrobacter freundii (2.0%). Specimen sources included the lower respiratory tract (52.1%), urine (17.3%), and blood (14.2%). Rates of resistance to many of the antibiotics tested remained stable during the 12-year study period. Carbapenems were the most active drugs tested against most of the bacterial species. E. coli and P. mirabilis remained susceptible to most of the drugs tested. Mean rates of resistance to 9 of the 12 drugs tested increased with Acinetobacter spp. Rates of resistance to ciprofloxacin increased over the study period for most species. Ceftazidime was the only agent to which a number of species (Acinetobacter spp., C. freundii, E. aerogenes, K. pneumoniae, P. aeruginosa, and S. marcescens) became more susceptible. The prevalence of multidrug resistance, defined as resistance to at least one extended-spectrum cephalosporin, one aminoglycoside, and ciprofloxacin, increased substantially among ICU isolates of Acinetobacter spp., P. aeruginosa, K. pneumoniae, and E. cloacae.

Surveillance of antimicrobial use and antimicrobial resistance in German intensive care units (SARI): a summary of the data from 2001 through 2004

Objective:

To report the experience gained over 4 years in working with the German SARI project (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units), and to compare SARI with data from the Swedish STRAMA and the US AUR surveillance system.

Methods:

Prospective unit and laboratory based surveillance was carried out in 40 German ICUs from 2001 through 2004. WHO 2004 definitions of defined daily doses (DDD) per 1,000 patient days (pd) were used to express antimicrobial consumption (AD). Apart from the proportion of resistant isolates (RP), the incidence density of resistant isolates (RD) was calculated on the basis of the number of resistant isolates per 1,000 pd. To determine the changes over time, the Wilcoxon signed rank test for paired samples was used.

Results:

From 1/2001 through 12/2004, 40 ICUs provided data on 53,399 isolates, a total of 789,569 DDD and 597,592 pd. Total AD ranged from 427 to 2,798, with the median being 1,351. There was no statistically significant change in total antimicrobial use, but a statistically significant decrease was observed in the use of aminoglycosides. RD was highest for MRSA with 4.4 resistant isolates/1,000 pd followed by imipenem resistant Pseudomonas aeruginosa with 1.7 resistant isolates/1,000 pd. The corresponding RPs were 21.5% and 23.2%. Over the 4-year period (2001–2004), significant increases were seen in the RDs of third generation cephalosporin and ciprofloxacin resistant Escherichia coli. In 2004, the mean RD reached 0.28 and 1.41, respectively. In comparison, the RP of selected pathogens was highest in the US ICUs and lowest in Swedish ICUs, with the exception of imipenem resistant P. aeruginosa.

Conclusion:

Antibiotic consumption remained stable over a period of 4 years, (the mean being 1,321 DDD/1,000 pd). The same applied to the situation regarding resistance in Staphylococcus aureus, enterococci and P. aeruginosa. For most pathogens the RP was higher in SARI ICUs than in Swedish ICUs, but lower than in US ICUs.

Lack of effect of fluoroquinolone resistance on mortality in subjects with Pseudomonas aeruginosa bacteraemia

OBJECTIVES

Despite the well-documented increase in fluoroquinolone resistance to Pseudomonas aeruginosa, the effect on pathogenicity is unknown. This paper will explore the clinical effect.

METHODS

A retrospective, observational, cohort study of 215 hospital inpatients was performed. Subjects with fluoroquinolone-resistant P. aeruginosa (FQRPA) bacteraemia were compared to subjects with fluoroquinolone-sensitive P. aeruginosa (FQSPA) bacteraemia from January 2000 to December 2003. Mortality prior to discharge, time to discharge, and time to negative culture were assessed. Additionally, baseline morbidity/mortality risk factors including Charlson morbidity score (CMS) were assessed.

RESULTS

Mortality prior to discharge (32 vs. 29%, P=0.73), mean days to discharge (17.5 vs. 14.6, P=0.24), and mean days to negative culture (3.6 vs. 3.2, P=0.1) did not differ between FQRPA and FQSPA, respectively. Active antibiotic treatment within 24h of drawn blood culture (FQRPA 63% vs. FQSPA 93%, P<0.0001) and median CMS (FQRPA 3 vs. FQSPA 5, P=0.004) differed significantly between the groups.

CONCLUSIONS

Subjects with FQRPA received active antibiotics less often within 24h of obtained culture. A large difference in mortality does not likely exist based on fluoroquinolone susceptibility. A study with greater enrollment must be conducted to determine if fluoroquinolone resistance imparts a smaller yet clinically significant impact on clinical outcomes.

In vitro fluoroquinolone susceptibility ofPseudomonas aeruginosaisolates from dogs with ulcerative keratitis

OBJECTIVE

To determine the in vitro fluoroquinolone susceptibility profiles of Pseudomonas aeruginosa isolates from dogs with ulcerative keratitis. Animals-27 dogs with P. aeruginosa-associated ulcerative keratitis.

PROCEDURES

P. aeruginosa isolates from dogs with ulcerative keratitis were collected during a 3-year period. Isolates were tested by use of the disk diffusion method for their susceptibility to 7 fluoroquinolones that are available as commercial ophthalmic preparations. The antimicrobials included second- (ciprofloxacin, ofloxacin, norfloxacin, and lomefloxacin), third- (levofloxacin), and fourth-generation (gatifloxacin and moxifloxacin) fluoroquinolones. Isolates were designated as susceptible, intermediate, or resistant to the various antimicrobials. The percentage of susceptible isolates was compared among individual fluoroquinolones and among fluoroquinolone generations.

RESULTS

None of the dogs had received topical or systemic fluoroquinolone treatment prior to referral. Twenty-seven P. aeruginosa isolates were collected during the study period. In vitro, bacterial resistance to the tested fluoroquinolones was infrequently identified (24/ 27 isolates were susceptible to all fluoroquinolones evaluated); susceptibility percentages ranged from 88.9% to 100% for individual antimicrobials. There were no significant differences among isolate susceptibilities to the individual antimicrobials or among generations of fluoroquinolones.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of these in vitro data, none of the 7 evaluated fluoroquinolones (individually or collectively by generation) appeared to offer a clinically important advantage in the treatment of P. aeruginosa-associated ulcerative keratitis in dogs. Among the P. aeruginosa isolates collected from dogs with ulcerative keratitis in this study, the likelihood of susceptibility to the fluoroquinolones evaluated was high.

Reducing neonatal nosocomial bloodstream infections through participation in a national surveillance system

A national nosocomial surveillance system for neonatal intensive care patients with a very low birthweight was set up in Germany in 2000 (NEO-KISS). Forty-eight neonatal intensive care units (NICUs) participated in the programme, which focused upon nosocomial bloodstream infections (BSIs) and pneumonia. Only data from NICUs participating for at least three years were included and the years compared. The relative risks and their 95% confidence intervals (CIs) were calculated and a multiple logistic regression analysis performed to identify significant risk factors. Twenty-four units that met the selection criteria accumulated data for 3856 patients and 152 437 patient-days in their first three years of participation. The incidence density of BSIs decreased significantly by 24% from 8.3 BSIs per 1000 patient-days in the first year to 6.4 in the third year. In the multiple logistic regression analysis, BSI in the third year of participation was significantly lower than in the first year of participation (odds ratio=0.73, 95% CI 0.60-0.89). The year of participation was an independent risk factor for BSI but not for pneumonia. Our data suggest that participation in ongoing surveillance of nosocomial infections in NICUs, requiring individual units to feedback data, may lead to a reduction in BSI rates.

Cost of Gram-negative resistance*

OBJECTIVE

It is unclear that infections with Gram-negative rods resistant to at least one major class of antibiotics (rGNR) have a greater effect on patient morbidity than infections caused by sensitive strains (sGNR). We wished to test the hypothesis that rGNR infections are associated with higher resource utilization.

DESIGN

Retrospective observational cohort study of prospectively collected data.

SETTING

University hospital surgical intensive care unit and ward.

PATIENTS

Surgical patients with at least one GNR infection.

MEASUREMENTS

We compared admissions treated for rGNR infection with those with sGNR infections. Primary outcomes were total hospital costs and hospital length of stay. Other outcomes included antibiotic treatment cost, in-hospital death, and intensive care unit length of stay. After univariate analysis comparing outcomes after rGNR infection with those after sGNR infection, multivariate linear regression models for hospital cost and length of stay were created to account for potential confounders.

MAIN RESULTS

Cost data were available for 604 surgical admissions treated for at least one GNR infection (Centers for Disease Control and Prevention criteria), 137 (23%) of which were rGNR infections. Admissions with rGNR infections were associated with a higher severity of illness at the time of infection (Acute Physiology and Chronic Health Evaluation II score, 17.6 +/- 0.6 vs. 13.9 +/- 0.3), had higher median hospital costs ($80,500 vs. $29,604, p < .0001) and median antibiotic costs ($2,607 vs. $758, p < .0001), and had longer median hospital length of stay (29 vs. 13 days, p < .0001) and median intensive care unit length of stay (13 days vs. 1 day, p < .0001). Infection with rGNR within the first 7 days of admission was independently predictive of increased hospital cost (incremental increase in median hospital cost estimated at $11,075; 95% confidence interval, $3,282-$20,099).

CONCLUSIONS

Early infection with rGNR is associated with a high economic burden, which is in part related to increased antibiotic utilization compared with infection with sensitive organisms. Efforts to control overuse of antibiotics should be pursued.

High prevalence of ceftazidime-resistant Klebsiella pneumoniae and increase of imipenem-resistant Pseudomonas aeruginosa and Acinetobacter spp. in Korea: a KONSAR program in 2004

A nationwide antimicrobial resistance surveillance has been conducted since 1997 in Korea. In this study, susceptibility test data generated in 2004 by KONSAR group hospitals were analyzed and compared to those at a commercial laboratory. In hospitals, the rank orders of organisms in 2004 were identical to those in 2003. The most prevalent species was Staphylococcus aureus (20.2%) in hospitals, but Escherichia coli (29.7%) in the commercial laboratory. The proportions of Enterococcus faecium to all isolates of Enterococcus faecalis plus E. faecium were 47.2% in hospitals and 24.9% in the commercial laboratory. The mean resistance rates of significant antimicrobial-organism combinations in hospitals were: oxacillin-resistant S. aureus (68%), oxacillin-resistant (penicillin- nonsusceptible) Streptococcus pneumoniae (68%), vancomycin-resistant E. faecium (25%), cefotaxime-resistant E. coli (14%), ceftazidime- and cefoxitin-resistant Klebsiella pneumoniae (34% and 32%, respectively), and imipenem-resistant Acinetobacter spp. and Pseudomonas aeruginosa (17% and 24%, respectively). In conclusion, oxacillin-resistant staphylococci, expanded-spectrum cephalosporin-resistant K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa were prevalent in 2004. Increasing trends were observed for vancomycin-resistant E. faecium, cefoxitin- resistant E. coli and K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa. Certain antimicrobial- organism combinations were also prevalent among the commercial laboratory-tested strains.

Patterns of antimicrobial resistance in a surgical intensive care unit of a university hospital in Turkey

Background

Several studies have reported higher rates of antimicrobial resistance among isolates from intensive care units than among isolates from general patient-care areas. The aims of this study were to review the pathogens associated with nosocomial infections in a surgical intensive care unit of a university hospital in Turkey and to summarize rates of antimicrobial resistance in the most common pathogens. The survey was conducted over a period of twelve months in a tertiary-care teaching hospital located in the south-eastern part of Turkey, Gaziantep. A total of 871 clinical specimens from 615 adult patients were collected. From 871 clinical specimens 771 bacterial and fungal isolates were identified.

Results

Most commonly isolated microorganisms were: Pseudomonas aeruginosa (20.3%), Candida species (15%) and Staphylococcus aureus (12.9%). Among the Gram-negative microorganisms P. aeruginosa were mostly resistant to third-generation cephalosporins (71.3–98.1%), while Acinetobacter baumannii were resistant in all cases to piperacillin, ceftazidime and ceftriaxone. Isolates of S. aureus were mostly resistant to penicillin, ampicillin, and methicillin (82–95%), whereas coagulase-negative staphylococci were 98.6% resistant to methicillin and in all cases resistant to ampicillin and tetracycline.

Conclusion

In order to reduce the emergence and spread of antimicrobial-resistant pathogens in ICUs, monitoring and optimization of antimicrobial use in hospitals are strictly recommended. Therefore local resistance surveillance programs are of most value in developing appropriate therapeutic guidelines for specific infections and patient types.

Emergence and resurgence of meticillin-resistant Staphylococcus aureus as a public-health threat

Staphylococcus aureus is a gram-positive bacterium that colonises the skin and is present in the anterior nares in about 25-30% of healthy people. Dependent on its intrinsic virulence or the ability of the host to contain its opportunistic behaviour, S aureus can cause a range of diseases in man. The bacterium readily acquires resistance against all classes of antibiotics by one of two distinct mechanisms: mutation of an existing bacterial gene or horizontal transfer of a resistance gene from another bacterium. Several mobile genetic elements carrying exogenous antibiotic resistance genes might mediate resistance acquisition. Of all the resistance traits S aureus has acquired since the introduction of antimicrobial chemotherapy in the 1930s, meticillin resistance is clinically the most important, since a single genetic element confers resistance to the most commonly prescribed class of antimicrobials--the beta-lactam antibiotics, which include penicillins, cephalosporins, and carbapenems.