Vancomycin-resistant Staphylococcus aureus: perspectives on measures needed for control

Treatment in Pd Patients of Peritonitis Caused by Gram-Positive Organisms with Single Daily Dose of Antibiotics

This study was a retrospective case analysis of treatment results of peritonitis in PD patients caused by gram-positive organisms in two different but comparable periods.

Cases were entered, regardless of status of exit site, or whether it was the patient's first or subsequent peritonitis episode.

Failure was defined as either recurrence of peritonitis (with same organism within four weeks of cessation of treatment) or the therapeutic decision to remove the catheter.

Cefazolin used in doses of 1.5 g once a day intraperitoneally (1.0 g if body weight was < 50 kg) with initial tobramycin until culture results became available resulted in a 77% overall cure rate compared to 74% cure in a similar group treated with vancomycin 2.0 g IP weekly (1.0 g if body weight < 50 kg).

Peritonitis caused by methicillin-resistant coagulase-negative staphylococci showed a high failure rate; the change to vancomycin after the initial treatment of these cases would be justified.

The cure rate of peritonitis caused by S. aureus is disappointingly low (58% with vancomycin, 67% with cefazolin). This is due to the high rate of exit-site infections with this organism.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

The 2013 Infection Prevention and Control (IP&C) Guideline for Cystic Fibrosis (CF) was commissioned by the CF Foundation as an update of the 2003 Infection Control Guideline for CF. During the past decade, new knowledge and new challenges provided the following rationale to develop updated IP&C strategies for this unique population:

1.The need to integrate relevant recommendations from evidence-based guidelines published since 2003 into IP&C practices for CF. These included guidelines from the Centers for Disease Control and Prevention (CDC)/Healthcare Infection Control Practices Advisory Committee (HICPAC), the World Health Organization (WHO), and key professional societies, including the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). During the past decade, new evidence has led to a renewed emphasis on source containment of potential pathogens and the role played by the contaminated healthcare environment in the transmission of infectious agents. Furthermore, an increased understanding of the importance of the application of implementation science, monitoring adherence, and feedback principles has been shown to increase the effectiveness of IP&C guideline recommendations.

2.Experience with emerging pathogens in the non-CF population has expanded our understanding of droplet transmission of respiratory pathogens and can inform IP&C strategies for CF. These pathogens include severe acute respiratory syndrome coronavirus and the 2009 influenza A H1N1. Lessons learned about preventing transmission of methicillin-resistantStaphylococcus aureus(MRSA) and multidrug-resistant gram-negative pathogens in non-CF patient populations also can inform IP&C strategies for CF.

Risk Factors and Costs Associated With Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Objectives:

To compare the cost of hospitalization of patients with methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) versus patients with methicillin-sensitive S. aureus (MSSA) BSI, controlling for severity of underlying illness; and to identify risk factors associated with MRSA BSI.

Design:

Retrospective case-control study based on medical chart review.

Setting:

A 640-bed, tertiary-care hospital in Seattle, Washington.

Patients:

All patients admitted to the hospital between January 1,1997, and December 31,1999, with S. aureus BSI confirmed by culture.

Results:

Twenty patients with MRSA BSI were compared with 40 patients with MSSA BSI. Univariate analysis identified 5 risk factors associated with MRSA BSI. Recent hospital admission (P = .006) and assisted living (P = .004) remained significant in a multivariate model. Costs were significantly higher per patient-day of hospitalization for MRSA BSI than for MSSA BSI ($5,878 vs $2,073; P = .003). When patients were stratified according to severity of illness as measured by the case mix index, a difference of $5,302 per patient-day was found between the two groups for all patients with a case mix index greater than 2(P<.001).

Conclusion:

These observations suggest that MRSA BSI significantly increases hospitalization costs compared with MSSA BSI, even when controlling for the severity of the patient's underlying illness. As MRSA BSI was also found to be significantly associated with a group of patients who have repeated hospitalizations, such infections contribute substantially to the increasing cost of medical care.

Vancomycin Control Measures at a Tertiary-Care Hospital: Impact of Interventions on Volume and Patterns of use

OBJECTIVE: Evaluate vancomycin prescribing patterns in a tertiary-care hospital before and after interventions to decrease vancomycin utilization.

DESIGN: Before/after analysis of interventions to limit vancomycin use.

SETTING: 420-bed academic tertiary-care center.

INTERVENTIONS: Educational efforts began August 10, 1994, and involved lectures to medical house staff followed by mailings to all physicians and posting of guidelines for vancomycin use on hospital information systems. Active interventions began November 15, 1994, and included automatic stop orders for vancomycin at 72 hours, alerts attached to the medical record, and, for 2 weeks only, computer alerts to physicians following each vancomycin order. Parenteral vancomycin use was estimated from the hospital pharmacy database of all medication orders. Records of a random sample of 344 patients receiving van-comycin between May 1, 1994, and April 30, 1995, were reviewed for an indication meeting published guidelines.

RESULTS: Vancomycin prescribing decreased by 22% following interventions, from 8.5 to 6.8 courses per 100 discharges (P<.05). The estimated proportion of van-comycin ordered for an indication meeting published guidelines was 36.6% overall, with no significant change following interventions. However, during the 2 weeks that computer alerts were in place, 60% of vancomycin use was for an approved indication.

CONCLUSIONS: Parenteral vancomycin prescribing decreased significantly following interventions, but the majority of orders still were not for an indication meeting published guidelines. Further improvement in the appropriateness of vancomycin prescribing potentially could be accomplished by more aggressive interventions, such as computer alerts, or by targeting specific aspects of prescribing patterns.

Effects of Essential Oils and Monolaurin on Staphylococcus aureus: In Vitro and In Vivo Studies

The antimicrobial properties of volatile aromatic oils and medium-chain fatty acids derived from edible plants have been recognized since antiquity. To give examples, Origanum oil, used as a food-flavoring agent, possesses a broad spectrum of antimicrobial activity due, at least in part, to its high content of phenolic derivatives such as carvacrol and thymol. Similarly, lauric acid, present in heavy concentrations in coconuts, forms monolaurin in the body that can inhibit the growth of pathogenic microbes. Using Staphylococcus aureus in broth cultures and a microdilution method, comparative efficacy of Origanum oil, and a constituent carvacrol, other essential oils and monolaurin were examined. Origanum oil was the most potent of the essential oils tested and proved bactericidal in culture to two strains of Staphylococcus aureus (ATCC #14154 and #14775) at 0.25 mg/mL. In vitro, monolaurin's effects mirrored Origanum oil. The combination of both was bactericidal at the 0.125 mg/mL concentration of each. In two separate In vivo experiments, injected Staphylococcus aureus (ATCC #14775) killed all 14 untreated mice within a 1-week period. In treated mice, over one third survived for 30 days when given oral Origanum oil daily for 30 days (6/14). Fifty percent of the mice survived for 30 days when receiving daily vancomycin (7/14) and monolaurin (4/8). Over 60% of mice survived when receiving a daily combination of Origanum oil and monolaurin (5/8). Origanum oil and/or monolaurin may prove to be useful antimicrobial agents for prevention and therapy of Staphylococcus aureus infections.

Catalytic mechanism and cofactor preference of dihydrodipicolinate reductase from methicillin-resistant Staphylococcus aureus

Given the rapid rise in antibiotic resistance, including methicillin resistance in Staphylococcus aureus (MRSA), there is an urgent need to characterize novel drug targets. Enzymes of the lysine biosynthesis pathway in bacteria are examples of such targets, including dihydrodipicolinate reductase (DHDPR, E.C. 1.3.1.26), which is the product of an essential bacterial gene. DHDPR catalyzes the NAD(P)H-dependent reduction of dihydrodipicolinate (DHDP) to tetrahydrodipicolinate (THDP) in the lysine biosynthesis pathway. We show that MRSA-DHDPR exhibits a unique nucleotide specificity utilizing NADPH (K(m)=12μM) as a cofactor more effectively than NADH (K(m)=26μM). However, the enzyme is inhibited by high concentrations of DHDP when using NADPH as a cofactor, but not with NADH. Isothermal titration calorimetry (ITC) studies reveal that MRSA-DHDPR has ∼20-fold greater binding affinity for NADPH (K(d)=1.5μM) relative to NADH (K(d)=29μM). Kinetic investigations in tandem with ITC studies show that the enzyme follows a compulsory-order ternary complex mechanism; with inhibition by DHDP through the formation of a nonproductive ternary complex with NADP(+). This work describes, for the first time, the catalytic mechanism and cofactor preference of MRSA-DHDPR, and provides insight into rational approaches to inhibiting this valid antimicrobial target.

Vancomycin: understanding its past and preserving its future

The increase in vancomycin use in the 1980s to treat antibiotic-associated colitis and methicillin-resistant Staphylococcus aureus (MRSA) is largely responsible for the appearance of vancomycin-resistant enterococcus, which in turn spawned isolated cases of vancomycin-resistant S. aureus. Perhaps most worrisome to clinicians are strains of MRSA that are heteroresistant to vancomycin; these isolates are difficult to detect. Appropriate use of vancomycin coupled with awareness of infection control measures is paramount to abrogating the emergence of new vancomycin-resistant MRSA organisms and preserving its future efficacy. The continued reliance on vancomycin for the treatment of MRSA infections will depend on whether vancomycin resistance can be minimized. Newer antibacterial agents, particularly those with activity toward MRSA and vancomycin-resistant enterococcus, such as linezolid, quinupristin/dalfopristin, daptomycin, and tigecycline, may take a more prominent clinical role when gram-positive bacteria resistance to vancomycin further escalate.

Genetic background and antibiotic resistance of Staphylococcus aureus strains isolated in the Republic of Georgia

The genetic composition and antibiotic sensitivities of 50 clinical isolates of Staphylococcus aureus obtained from various clinics in the Republic of Georgia were characterized. S. aureus strains ATCC 700699 and ATCC 29737 were included as reference standards in all analyses. All 52 strains had identical 16S rRNA profiles. In contrast, pulsed-field gel electrophoresis (PFGE) identified 20 distinct PFGE types among the 52 strains examined, which indicates that PFGE is more discriminating than is 16S rRNA sequence analysis for differentiating S. aureus strains. The results of our PFGE typing also suggest that multiple genetic subpopulations (related at the ca. 85% similarity level, based on their SmaI PFGE patterns) exist among the Georgian S. aureus strains. Twenty-two of the 50 Georgian strains were methicillin resistant and PCR positive for mecA, and 5 strains were methicillin sensitive even though they possessed mecA. None of the strains were vancomycin resistant or contained vanA. The nucleotide sequences of mecA fragments obtained from all mecA-containing strains were identical. Our data indicate that the population of S. aureus strains in Georgia is fairly homogeneous and that the prevalence of methicillin-resistant, mecA-positive strains is relatively high in that country.

The search for new antimicrobials: why we need new options

The increasing identification of antibiotic-resistant pathogens that cause serious infections cannot be ignored. Although the future cannot be predicted with certainty, it is surely possible that an extensive epidemic of resistant bacterial infections could potentially harm millions of people. Given that it takes more than 10 years to establish the efficacy and safety of new compounds, there is an urgent need to restock the antibiotic pipeline. Only a few new antibacterial agents have received approval by the US Food and Drug Administration in the last 5 years, including linezolid in 2001, cefditoren, pivoxil and ertapenem in 2002, gemifloxacin and daptomycin in 2003, and telithromycin in 2004. Many of these agents are improved derivatives from established classes of antibiotics, and several are directed primarily at resistant Gram-positive bacteria (e.g., linezolid and daptomycin). One promising new addition is the recent approval of tigecycline (Tigacyl, Wyeth) in June 2005.

[Staphylococcus aureus infections: new challenges from an old pathogen]

Staphylococcus aureus is a versatile organism with several virulent characteristics and resistance mechanisms at its disposal. It is also a significant cause of a wide range of infectious diseases in humans. S. aureus often causes life-threatening deep seated infections like bacteremia, endocarditis and pneumonia. While traditionally confined mostly to the hospital setting, methicillin-resistant S. aureus (MRSA) is now rapidly becoming rampant in the community. Community-acquired MRSA is particularly significant because of its potential for unchecked spread within households and its propensity for causing serious skin and pulmonary infections. Because of the unfavorable outcome of many MRSA infections with the standard glycopeptide therapy, new antimicrobial agents belonging to various classes have been introduced and have been evaluated in clinical trials for their efficacy in treating resistant staphylococcal infections. A number of preventive strategies have also been suggested to contain the spread of such infections. In this review, we address the recent changes in the epidemiology of S. aureus and their impact on the clinical manifestations and management of serious infections. We also discuss new treatment modalities for MRSA infections and emphasize the importance of preventive approaches.

Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus (MRSA) remains endemic in many UK hospitals. Specific guidelines for control and prevention are justified because MRSA causes serious illness and results in significant additional healthcare costs. Guidelines were drafted by a multi-disciplinary group and these have been finalised following extensive consultation. The recommendations have been graded according to the strength of evidence. Surveillance of MRSA should be undertaken in a systematic way and should be fed back routinely to healthcare staff. The inappropriate or unnecessary use of antibiotics should be avoided, and this will also reduce the likelihood of the emergence and spread of strains with reduced susceptibility to glycopeptides, i.e. vancomycin-intermediate S. aureus/glycopeptide-intermediate S. aureus (VISA/GISA) and vancomycin-resistant S. aureus (VRSA). Screening for MRSA carriage in selected patients and clinical areas should be performed according to locally agreed criteria based upon assessment of the risks and consequences of transmission and infection. Nasal and skin decolonization should be considered in certain categories of patients. The general principles of infection control should be adopted for patients with MRSA, including patient isolation and the appropriate cleaning and decontamination of clinical areas. Inadequate staffing, especially amongst nurses, contributes to the increased prevalence of MRSA. Laboratories should notify the relevant national authorities if VISA/GISA or VRSA isolates are identified.

Minimum inhibitory concentrations of herbal essential oils and monolaurin for gram-positive and gram-negative bacteria

New, safe antimicrobial agents are needed to prevent and overcome severe bacterial, viral, and fungal infections. Based on our previous experience and that of others, we postulated that herbal essential oils, such as those of origanum, and monolaurin offer such possibilities. We examined in vitro the cidal and/or static effects of oil of origanum, several other essential oils, and monolaurin on Staphylococcus aureus, Bacillus anthracis Sterne, Escherichia coli, Klebsiella pneumoniae, Helicobacter pylori, and Mycobacterium terrae. Origanum proved cidal to all tested organisms with the exception of B. anthracis Sterne in which it was static. Monolaurin was cidal to S. aureus and M. terrae but not to E. coli and K. pneumoniae. Unlike the other two gram-negative organisms, H. pylori were extremely sensitive to monolaurin. Similar to origanum, monolaurin was static to B. anthracis Sterne. Because of their longstanding safety record, origanum and/or monolaurin, alone or combined with antibiotics, might prove useful in the prevention and treatment of severe bacterial infections, especially those that are difficult to treat and/or are antibiotic resistant.

Oxazolidinones: new players in the battle against multi-resistant Gram-positive bacteria

For many years the pharmaceutical industry did not pursue the development of antimicrobial agents that specifically targeted Gram-positive bacteria. Semi-synthetic penicillins and vancomycin were the mainstays of therapy for methicillin-susceptible and -resistant strains of staphylococci, respectively, as was penicillin for Streptococcus pneumoniae and beta-lactam-aminoglycoside combinations for serious enterococcal infections. In the 1980s enterococci resistant to glycopeptides emerged, followed shortly thereafter by a dissemination of penicillin-insensitive S. pneumoniae and, more recently, the occurrence of vancomycin-intermediately susceptible Staphylococcus aureus. The emergence of fully glycopeptide-resistant S. aureus is clearly on the horizon. Multi-resistant Gram-positive bacteria now pose an important therapeutic challenge for clinicians. New drugs with activity against some of these dangerous pathogens have recently been pursued, and linezolid, the first member of the oxazolidinone class, has now been licensed for clinical use in many countries. This drug has excellent in vitro and in vivo activity against all clinically relevant multi-resistant Gram-positive cocci and fills an important void in infectious disease chemotherapy.

Community-based outpatient practice of antibiotics use in Tehran

OBJECTIVES

To study patterns of outpatient antibiotic use in the Great Tehran, in order to develop interventional strategies in rationalizing drug and especially antibiotic use.

MATERIALS AND METHODS

Ten-percent random sample of all prescription belonging to practitioners in south of Tehran and kept in a data bank was sampled. Drug use indicators were determined in order to develop intervention program to promote rational drug use among practitioners in Tehran. Based on the values of drug use indicators, an interventional program, a program of continuing medical education (CME) targeting rational use of drugs, was designed. Eighty general practitioners (GPs) who contributed to the data bank were selected and allocated to two groups, intervention group and control group. Each group contained 40 GPs. Drug use indicators were measured in each group three times; before and in two intervals after the intervention. The indicators were compared before and after as well as between groups.

RESULTS

The drug use indicators determined through the data bank showed that 19% of all prescribed drugs in data bank were antibiotics, which ranked second only after 'analgesics and CNS drugs' with 24%. The drug use indicators were improved in the intervention group (the average number of drugs per encounter lowered from 4.3 +/- 0.5 pre-intervention to 3.6 +/- 0.1 six months thereafter, p value = 0.001). The percentage of encounters with an antibiotic prescribed were lowered in intervention group compared with control group but the difference was not statistically significant. The intervention made a change to all other measured indicators but not all of them were statistically significant.

CONCLUSIONS

Irrational use of antibiotics can improve by appropriate educational intervention, using CME programs.

The Delivery of Benzyl Penicillin toStaphylococcus aureusBiofilms by Use of Liposomes

The delivery of benzyl penicillin [penicillin G (pen-G)] encapsulated in cationic liposomes to a pen-G-sensitive strain of Staphylococcus aureus immobilized in biofilms has been investigated. The cationic liposomes prepared by extrusion (VETs, diameter approximately 140 nm) were composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol, and dimethylammonium ethane carbamoyl cholesterol (DC-chol) at a molar ratio of 1.0:0.49:0.43. This composition containing 22 mole% of the cationic lipid DC-chol has been found previously (Kim et al. Colloids Surfaces A 1999, 149, 561-570) to be optimum for adsorption of the liposomes on S. aureus biofilms. The effectiveness of the liposomes to deliver pen-G to the biofilms immobilized on microtitre plates was assessed from the rate of growth of the cells after exposure to the liposomal drug carrier relative to free pen-G at the same concentration. The time to reach maximum growth rate from biofilms was investigated as a function of overall drug concentration in a range 2.9 x 10- 3 mM to 1.09 mM and as a function of time of exposure to liposomal drug in a range 1.5 s to 2 h. Liposomal drug delivery was most effective relative to free drug at low overall drug concentrations and short times of exposure. The time to reach maximum growth rate from S. aureus biofilms could be extended by a factor of approximately 4 relative to free drug by the use of liposomally encapsulated pen-G. The results were supported by direct measurements of the distribution of pen-G between biofilm and supernatant which showed enhanced values relative to free drug and a transient preferential uptake of drug induced by the liposomes. The study demonstrates that for low drug concentrations and short exposure times liposomal drug delivery greatly enhances the effectiveness of pen-G for inhibiting the growth of bacterial biofilms of the potentially pathogenic bacterium Staphylococcus aureus.

Staphylococcus aureus with reduced susceptibility to vancomycin

Infections with Staphylococcus aureus with reduced susceptibility to vancomycin continue to be reported, including 2 cases caused by S. aureus isolates with full resistance to vancomycin. This review first outlines the definitions of vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) and risk factors for infection. Next, we describe the mechanisms of resistance and methods of laboratory detection of the organisms. Finally, we address infection control and management issues associated with isolation of VISA and VRSA.

Antibacterial screening of plants used in Iranian folkloric medicine

Fifty methanolic plant extracts belonging to 44 plant species of 33 families finding use in Iranian folkloric medicine were screened for antibacterial activity. Thirty samples, including 28 species in 20 families, had antibacterial activity against at least on one of the bacteria. Among the active plants, 32.6% were active against G(-), 62% against G(+), and 47.3% against both G(-) and G(+) bacteria. Dianthus coryophyllus was active against all tested G(-) and G(+) bacteria except Micrococcus luteus. Most susceptible G(-) bacteria were Klebsiella pneumoniae and Bordetella bronchiseptica and least susceptible G(-) bacterium was Escherichia coli. In G(+) bacteria, most and least susceptible were Staphylococcus aureus and M. luteus, respectively. The least MIC, as 0.62 mg/ml, belonged to Myrtus communis seeds against S. aureus, Bacillus cereus and B. bronchiseptica, and to Terminalia chebula ripe seeds against S. aureus.

Effectiveness and safety of enteral vancomycin to control endemicity of methicillin-resistant Staphylococcus aureus in a medical/surgical intensive care unit

A prospective trial was undertaken to assess the effectiveness and safety of enteral vancomycin in controlling methicillin-resistant Staphylococcus aureus (MRSA) in an endemic setting. Over the 49 month period patients aged >14 years were enrolled, following admission to a medical/surgical intensive care unit (ICU) and expected to require ventilation for three days or more. A total of 799 patients were included in the trial. Period one, 1 July 1996-30 April 1997, (N=140), was observational. During period two, 1 May 1997-30 September 1998, (N=258), surveillance samples were obtained. MRSA carriers were isolated and received enteral vancomycin. During period three, 1 October 1998-31 July 2000, (N=400), all ventilated patients were given selective digestive decontamination (SDD) with polymyxin E, tobramycin, amphotericin B and vancomycin and four days of intravenous cefotaxime. The primary endpoints were: (1) incidence of patients with diagnostic samples positive for MRSA acquired on the ICU; (2) incidence of patients with vancomycin-resistant enterococci (VRE) in surveillance or diagnostic samples; (3) incidence of patients with samples positive for S. aureus with intermediate sensitivity to glycopeptides (GISA). The incidence of patients with MRSA in diagnostic samples were 31%, 14%, and 2% in periods one, two and three, respectively (P<0.001). There was a VRE outbreak involving 13 patients during period three. VRE disappeared with no change in policy. GISA was not detected. These findings support the effectiveness and safety of enteral vancomycin in the control of MRSA.

Tratamento e prevenção das infecções e da colonização por Staphylococcus aureus

The number of Staphylococcus aureus (S. aureus) community and nosocomial acquired infections have increased in the last twenty years. Between 1990 and 1992, this pathogen has become the most frequent source of nosocomial infections 1,2. On the other hand, as result of antibiotherapy selection pressure, we observe a dramatic increase in the methicillin-resistant S. aureus (MRSA) infections 3,4. With the recent emergence of multiresistant strains, including glycopeptides resistance, the treatment of these infections became still more difficult 2,4-6. It's important to prevent resistant strains emergence. To prevent further emergence of resistant strains, the use of antibiotherapy must be optimised, laboratory methods for the detection of resistant pathogens must be enhanced and strict precautions should be taken following of the infection or colonization of patients 6-10. In this paper, we review anti-staphylococci history evolution and point out the present recommendations for the treatment and prevention of Staphylococcus aureus infections and colonization.

Hospital resource use and cost of treatment with linezolid versus teicoplanin for treatment of serious gram-positive bacterial infections among hospitalized patients from South America and Mexico: results from a multicenter trial

BACKGROUND

Linezolid is a novel oxazolidinone antibiotic that is effective for the treatment of gram-positive bacterial infections. The oral formulation has the potential to reduce length of stay (LOS) when used as a substitute for parenteral glycopeptide antibiotics. In a recent multinational trial comparing linezolid (i.v. followed by oral administration) with teicoplanin (i.v. alone or switched to i.m. administration), linezolid was found to have better efficacy (P = 0.005) and similar safety for treating serious gram-positive infections.

OBJECTIVE

The purpose of this study was to compare hospital resource use (primarily LOS) and cost of treatment between linezolid and teicoplanin for hospitalized patients with serious gram-positive infections in South America and Mexico using data from the multinational trial.

METHODS

In a multinational, Phase IIIb, open-label, comparator-controlled trial, data were collected from hospitalized patients in centers in 6 South America can countries and Mexico with suspected or confirmed serious gram-positive infections. Patients were randomly assigned to receive i.v. linezolid 600 mg BID (for the entire treatment period [7-28 days] or switched to oral linezolid 600 mg BID) or i.v. teicoplanin (for the entire treatment period or switched to i.m. teicoplanin) dosed per approved prescription information. Data on direct medical resource utilization were collected for each patient, including duration and doses of study medication, location of hospitalization and LOS, comedications, tests and procedures, and outpatient service usage. Unit costs for the medical resources were obtained from secondary sources.

RESULTS

A total of 203 patients (97 treated with linezolid and 106 treated with teicoplanin) were enrolled from these 7 countries. The unadjusted results showed that compared with teicoplanin, patients treated with linezolid had a 3.1-day shorter mean i.v. antibiotic treatment duration (P < 0.001), a 2.0- to 2.2-day shorter median and mean LOS (P = 0.03), and a 311 US dollars lower mean total cost of treatment (P = NS). After controlling for age, race, sex, site of infection, inpatient location when the antibiotic treatment started, number of historical and current comorbidities, and whether the patient had a diagnosis of systemic inflammatory response syndrome or sepsis, the multivariate adjusted results were similar to the unadjusted results. The linezolid group had a 1.6-day shorter adjusted LOS or 66% greater odds of early discharge (P = 0.049) and a 335 US dollars lower adjusted mean total cost of treatment (P = NS).

CONCLUSION

Linezolid was associated with shorter LOS and duration of IV antibiotic treatment than teicoplanin for serious gram-positive infections in the population studied. Linezolid therapy has the potential to reduce the total cost of treatment.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Overview of resistant gram-positive pathogens in the surgical patient

Staphylococci and enterococci are the most common pathogens in surgical-site and bloodstream infections. The emergence of drug resistance among these gram-positive bacteria thus poses a substantial threat to patients with surgical infections. Resistance to methicillin/oxacillin is frequently observed in Staphylococcus aureus isolates and is often accompanied by multidrug resistance. Vancomycin is usually the treatment of choice for infections caused by methicillin-resistant S. aureus (MRSA), so the recent appearance of S. aureus isolated with intermediate sensitivity to vancomycin is cause for concern. Vancomycin resistance has already appeared in most species of enterococci. Infections caused by vancomycin-resistant enterococci (VRE) are associated with increased mortality compared to infections caused by vancomycin-sensitive isolates. Measures for preventing vancomycin resistance include reducing the use of vancomycin and other agents that appear to be associated with VRE, including third-generation cephalosporins and anti-anaerobic drugs. Third-generation cephalosporins have also been implicated in the increased prevalence of MRSA infections. Prudent use of existing antibiotics is an essential strategy for combating the rising tide of drug-resistant gram-positive pathogens.

Quinupristin/dalfopristin

Gram-positive pathogens are associated with both community- and hospital-acquired infections. These infections may be life-threatening in hospitalised patients, especially in those with significant underlying acute or chronic diseases. Prompt and appropriate antimicrobial therapy is essential for avoiding morbidity and mortality. The concept of appropriate therapy is being redefined by increasing antimicrobial resistance, especially amongst Gram-positive pathogens. This has been most dramatic with penicillin-resistant Streptococcus pneumoniae in the community, including cross-resistance to other classes of antimicrobial agents. In the US, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) with community isolates is significant. For hospital-acquired Gram-positive pathogens, MRSA, vancomycin-resistant Enterococcus species and vancomycin-intermediate resistant and -resistant S. aureus are a great concern, particularly as the frequency of recovery of these pathogens from infected patients increases. The net result of these various resistance issues is a reduction in the number of appropriate antimicrobial agents for treating infected patients. Quinupristin/dalfopristin is a parental streptogramin with a spectrum of activity that includes Gram-positive pathogens, including those resistant to other classes of antimicrobial compounds. In this review, data summarising the frequency of recovered Gram-positive pathogens from various infectious diseases, the escalating prevalence of resistance amongst Gram-positive pathogens and the factors making quinupristin/dalfopristin a suitable agent for treating patients infected with Gram-positive organisms will be discussed.

Resistance to beta-lactams and glycopeptides in staphylococci and streptococci

Molecular mechanisms of the action of beta-lactam and glycopeptide antibiotics, as well as genetic background and phenotypical features of the resistance of staphylococci, streptococci and enterococci to these antibiotics are reviewed. Furthermore, susceptibility patterns concerning beta-lactam and glycopeptide drugs of staphylococcal, streptococcal, as well as enterococcal strains isolated from clinical specimens at the Semmelweis University of Medicine, Budapest, Hungary between January 1997 and December 2000 are also presented.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S. aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S. aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S. aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

Infection control in the ICU

Nosocomial infections (NIs) now concern 5 to 15% of hospitalized patients and can lead to complications in 25 to 33% of those patients admitted to ICUs. The most common causes are pneumonia related to mechanical ventilation, intra-abdominal infections following trauma or surgery, and bacteremia derived from intravascular devices. This overview is targeted at ICU physicians to convince them that the principles of infection control in the ICU are based on simple concepts and that the application of preventive strategies should not be viewed as an administrative or constraining control of their activity but, rather, as basic measures that are easy to implement at the bedside. A detailed knowledge of the epidemiology, based on adequate surveillance methodologies, is necessary to understand the pathophysiology and the rationale of preventive strategies that have been demonstrated to be effective. The principles of general preventive measures such as the implementation of standard and isolation precautions, and the control of antibiotic use are reviewed. Specific practical measures, targeted at the practical prevention and control of ventilator-associated pneumonia, sinusitis, and bloodstream, urinary tract, and surgical site infections are detailed. Recent data strongly confirm that these strategies may only be effective over prolonged periods if they can be integrated into the behavior of all staff members who are involved in patient care. Accordingly, infection control measures are to be viewed as a priority and have to be integrated fully into the continuous process of improvement of the quality of care.

Hand hygiene--comparison of international recommendations

The value of hand hygiene for the prevention of cross-infection was first observed in the middle of the 19th century. Since then, which procedure is the most suitable for hand hygiene has been repeatedly discussed and several different guidelines and recommendations have been published. The aim of this review is to compare different recommendations for hand hygiene regarding technique and indication. Medline, the internet and a personal library were searched to obtain as many written recommendations as possible. In addition, a small questionnaire was sent by e-mail to 20 international colleagues. As a result, written recommendations from 10 countries could be compared. Recommended methods of hand hygiene include handwashing (washing hands with plain soap), hygienic handwash (washing hands with medicated soap) and hygienic hand-rub (use of antiseptic rubs). In most countries handwashing and hygienic handwash are the methods of choice and only in central European countries is hygienic hand-rub the preferred technique. Situations in which performance of hand hygiene is recommended are comparable. However, no single indication is recommended in all guidelines. Hand hygiene is most often recommended before performing invasive procedures and after microbial contamination. Guidelines should be clear and easy to follow for them to become standard of care. Thus, guidelines are needed that do not leave to the health care worker a decision as to whether hand hygiene is indicated.

New anti-Gram-positive agents

As the prevalence of resistant Gram-positive organisms in the critical care unit has increased, so have the associated morbidity and mortality and the cost of their treatment. As a result, more toxic and less active second-line agents and combinations of agents are used, often with limited evidence of clinical benefit. Although widely used, the role of glycopeptides is limited by increasing resistance and poor pharmacokinetics. New agents now in use, such as quinupristin/dalfopristin and Linezolid (Zyvox; Pharmacia & Upjohn, Kalamazoo, MI), show promise, as do diverse agents in development. The future is likely to bring greater therapeutic choice but, inevitably, further resistance.

Emergence of methicillin-resistant Staphylococcus aureus with intermediate glycopeptide resistance: clinical significance and treatment options

Methicillin-resistant Staphylococcus aureus is a pathogen that is associated with serious infections that pose a significant risk of morbidity and mortality because of their multidrug resistant nature. Until recently, therapeutic options were limited to vancomycin, making the use of this drug widespread. Unfortunately, the continued application of this drug has led to the emergence of glycopeptide intermediate susceptible S. aureus (GISA). By definition, these organisms demonstrated a vancomycin minimum inhibitory concentration (MIC) of >4 mg/L and <32 mg/L. However, although the mechanism of resistance is not fully elucidated at this time, GISA strains have demonstrated thickened or aggregated cell walls, an increase in penicillin binding proteins and greater autolytic activity. At present, the overall number of reported cases of GISA is relatively low. In most cases, thus far, prolonged courses of vancomycin were reported. A few cases reported monitoring serum vancomycin concentrations but because of limited information, no association with outcome can be made. Whether these GISA strains will become more widespread or evolve into fully glycopeptide resistant strains is unknown at this time. Although there are a number of new agents that possess activity against these pathogens, there is no consensus regarding specific recommendations for treatment. Strict infection control practices, routine screening for resistance and controlled use of antibacterial agents, especially vancomycin, are critical steps in preventing the further development of resistance among staphylococci.

Antimicrobial management strategies for Gram-positive bacterial resistance in the intensive care unit

This article summarizes the current situation with Gram-positive infections, including the two primary consequences-failure to cure and resistance-relevant to the intensive care unit. The past few years have seen Enterococcus faecium resistance to vancomycin increase from 10% of strains to approaching 60% of strains in some centers. Failure is now so frequent that vancomycin can no longer be safely used. This has lead to use of two new antibiotics, quinupristin/dalfopristin (Synercid), first marketed in the United States in September 1999, and linezolid (Zyvox), which reached the U.S. market in May 2000. Both of these agents are being used to treat culture-proven vancomycin-resistant E. faecium. The calculated areas under the inhibitory curve (AUIC) values of vancomycin, even when its minimal inhibitory concentration (MIC) is 4.0 microg/mL, show almost all vancomycin-resistant E. faecium have AUICs <125. This explains failure, as well as the further selection of this bacteria into subpopulations with progressively higher MICs. Less well defined, but potentially an even greater problem, is the poor efficacy of vancomycin against multiresistant Staphylococcus aureus. Here, there is evidence of clinical failure in lower respiratory tract infection patients, but in most cases the MIC values of the organism have not risen to the point where AUICs are <125. However, the minimum bactericidal concentration of this organism may be considerably higher than its MIC, and in other cases there may be a high inoculum effect or a protein-binding effect to explain the failure of vancomycin to kill multiresistant S. aureus. Besides the increasing use of the new agents, strategies to manage these two increasingly resistant Gram-positive infections include cephalosporin restriction, switch and streamlining when cultures come back from the lab, combination regimens, and cycling in selected intensive care units.

Increasing resistance to vancomycin and other glycopeptides in Staphylococcus aureus

Strains of Staphylococcus aureus with reduced susceptibility to glycopeptides have been reported from Japan, the United States, Europe, and the Far East. Although isolates with homogeneous resistance to vancomycin (MICs = 8 microg/mL) continue to be rare, there are increasing reports of strains showing heteroresistance, often with vancomycin MICs in the 1-4 microg/mL range. Most isolates with reduced susceptibility to vancomycin appear to have developed from preexisting methicillin-resistant S. aureus infections. Many of the isolates with reduced susceptibility to glycopeptides have been associated with therapeutic failures with vancomycin. Although nosocomial spread of the vancomycin-intermediate S. aureus (VISA) strains has not been observed in U.S. hospitals, spread of VISA strains has apparently occurred in Japan. Broth microdilution tests held a full 24 hours are optimal for detecting resistance in the laboratory; however, methods for detecting heteroresistant strains are still in flux. Disk-diffusion tests, including the Stokes method, do not detect VISA strains. The Centers for Disease Control and Prevention and other groups have issued recommendations regarding appropriate infection control procedures for patients infected with these strains.

MRSA carriage: the relationship between community and healthcare setting. A study in an Italian hospital

From May 1997 to June 1998, all patients admitted to the study institution were screened at entry for MRSA carriage (both colonization and infection). Eighty-six MRSA carriers were identified; of these, 85 were nasal carriers. Risk factors were compared to those of 86 controls. Although the vast majority of both carriers and controls had at least one previous hospital stay, carriers were less likely than controls to be referred from a community setting, and had resided within the community for a shorter time before the current admission. The number of underlying conditions was comparable in the two groups, but those infected were more likely to have cancer than the controls. While community-acquired MRSA carriage is rare, exposure to a health care setting (particularly if repeated) within six months from the current admission, is a risk factor for MRSA carriage and introduction of the organism into an institution.

Analysis of 42 cases of septicemia caused by an epidemic strain of methicillin-resistant Staphylococcus aureus: evidence of resistance to vancomycin

Recent case reports of vancomycin treatment failures in the United States, Japan, and France have prompted a retrospective analysis of 42 cases of septicemia caused by epidemic methicillin-resistant Staphylococcus aureus strain 15 (EMRSA-15), which is the most prevalent epidemic strain of methicillin-resistant S. aureus in the United Kingdom; all cases occurred in a teaching hospital in Manchester, United Kingdom, between 1994 and 1998. Mortality was lowest (4%) in patients with rifampin-susceptible isolates treated with vancomycin and rifampin. It rose to 38% in patients who were treated with both antibiotics but in whom the organism became resistant to rifampin during therapy, and it reached 78% in patients who had rifampin-resistant isolates or in whom rifampin was contraindicated (P<.0001; Fisher exact test, 2-tailed). All isolates were susceptible to vancomycin by conventional laboratory testing, but susceptibility was lost by growth in vancomycin in vitro, becoming resistant at a minimum inhibitory concentration of 8 mg/L. This was associated with accumulation of cell-wall material. The deoxyribonucleic acid fingerprint remained unchanged. This study suggests that rifampin played a key role in the prevention of deaths caused by an epidemic strain of methicillin-resistant S. aureus that readily gave rise to a subpopulation with reduced susceptibility to vancomycin.

Clinical impact of rapid oxacillin susceptibility testing using a PCR assay in Staphylococcus aureus bactaeremia

OBJECTIVES

The aim of this work was to establish the clinical impact of rapid oxacillin susceptibility testing in nosocomial Staphylococcus aureus bacteraemia.

METHODS

This study was performed in 145 critically ill patients infected by S. aureus. Patients were randomly assigned to one of two groups: patients for whom susceptibility testing was performed using a rapid same day multiplex PCR assay for detection of the staphylococcal mecA (mean delay of response: 6 h) and those for whom testing was accomplished using traditional overnight techniques (21 h).

RESULTS

The results of this study showed no significant difference between the two groups in terms of age, Simplified Acute Physiologic Score, severity of infection, severity of underlying disease and clinical outcome (control vs. PCR): unfavourable outcome of infection, 12.32 vs. 12.5%; 95% CI for the difference = -11.49 to 11.09 (P = 0.975); unfavourable general outcome, 16.43 vs. 20.83%; 95% CI for the difference = -17.35 to 8.50 (P = 0.497). For the oxacillin-susceptible S. aureus bactaeraemia, results were: unfavourable outcome of infection = 13.04 vs. 11.11%; 95% CI for the difference = -11.38 to 16.18 (P = 0.767); unfavourable general outcome = 13.04 vs. 20.37%; 95% CI for the difference = -22.12 to 8.07 (P = 0.331).

CONCLUSION

This study seemed to demonstrate that rapid oxacillin susceptibility testing using a PCR assay did not have a major impact on the care and outcome of patients with S. aureus bactaeremia.

Evidence of inappropriate use of vancomycin in a university affiliated hospital in Brazil

OBJECTIVE

To evaluate the appropriateness of use of vancomycin in a University affiliated Hospital in Brazil.

METHODS

One hundred sequential therapeutic courses of vancomycin were retrospectively examined through a chart review. The prescriptions were evaluated in terms of indication, use of critical process indicators, and use of outcome measurements according to an adapted version of the criteria recommended by the American Society of Health-System Pharmacists.

RESULTS

The indication for use was appropriate in 39% of the cases. Critical process indicators indicated frequent inappropriate use, mainly in relation to a low frequency of bacterial cultures (54%), infrequent determination of creatinine levels prior to therapy (57%), incorrect dosage (42%), incorrect duration of therapy (63%), and infrequent determination of serum levels of vancomycin (73%). It was impossible to evaluate outcome measurements, since data were not collected in most patients. Larger discrepancies between recommendation and practice were detected in Paediatrics and Paediatric Pneumology Services.

CONCLUSION

The misuse of vancomycin in our hospital is very common according to standard guidelines, demanding new policies of control in order to diminish the possibility of the emergence of multi-resistant strains.

Antimicrobial resistance in Staphylococcus aureus

Recognized since 1883 as a common cause of infection, Staphylococcus aureus' preantimicrobial-era bacteremia mortality rate was 82%. The mortality of that era threatens to return as evidence of growing vancomycin resistance undermines the utility of vancomycin therapy. Successful treatment of S. aureus infections requires knowledge of its antimicrobial resistance capacity.

In-vitro and in-vivo antibacterial activity of BI 397, a new semi-synthetic glycopeptide antibiotic

BI 397 (formerly A-A-1) is a semisynthetic derivative of the teicoplanin-like glycopeptide A40926. It was more active in vitro against staphylococci (including some teicoplanin-resistant strains) than teicoplanin and vancomycin. Against streptococci (including penicillin-resistant strains) BI 397 has activity comparable with that of teicoplanin and better than vancomycin. BI 397, when administered to rats by the i.v. route, gives high and long lasting blood levels. It shows excellent activity in models of acute septicaemia in immunocompetent and neutropenic mice. In a rat staphylococcal endocarditis model it is as effective as teicoplanin and vancomycin at reducing bacterial loads in the heart, but at lower dosages and with a reduced number of daily treatments compared with the two glycopeptide controls. BI 397 is highly efficacious in clearing penicillin-susceptible and -resistant pneumococci from lungs of immunocompetent and neutropenic rats. The data from these studies show that BI 397 combines an excellent in-vitro antibacterial activity with favourable pharmacokinetic behaviour resulting in potent in-vivo activity.