Consumption of imipenem correlates with beta-lactam resistance in Pseudomonas aeruginosa

Impact of antibiotic use on carbapenem resistance in Pseudomonas aeruginosa: is there a role for antibiotic diversity?

In this study, we aimed to evaluate the relationship between the rates of resistance of Pseudomonas aeruginosa to carbapenems and the levels and diversity of antibiotic consumption. Data were retrospectively collected from 20 acute care hospitals across 3 regions of Switzerland between 2006 and 2010. The main outcome of the present study was the rate of resistance to carbapenems among P. aeruginosa. Putative predictors included the total antibiotic consumption and carbapenem consumption in defined daily doses per 100 bed days, the proportion of very broad-spectrum antibiotics used, and the Peterson index. The present study confirmed a correlation between carbapenem use and carbapenem resistance rates at the hospital and regional levels. The impact of diversifying the range of antibiotics used against P. aeruginosa resistance was suggested by (i) a positive correlation in multivariate analysis between the above-mentioned resistance and the proportion of consumed antibiotics having a very broad spectrum of activity (coefficient = 1.77; 95% confidence interval, 0.58 to 2.96; P < 0.01) and (ii) a negative correlation between the resistance and diversity of antibiotic use as measured by the Peterson homogeneity index (coefficient = -0.52; P < 0.05). We conclude that promoting heterogeneity plus parsimony in the use of antibiotics appears to be a valuable strategy for minimizing the spread of carbapenem resistance in P. aeruginosa in hospitals.

Seasonality and temporal correlation between community antibiotic use and resistance in the United States

BACKGROUND

Therapeutic antibiotic use in humans is a significant driver of antibiotic resistance. The seasonal effect of antibiotic use on antibiotic resistance has been poorly quantified because of lack of large-scale, spatially disaggregated time-series data on antibiotic use and resistance.

METHODS

We used time-series analysis (Box-Jenkins) on US antibiotic usage from IMS Health and on antibiotic resistance from The Surveillance Network from 1999-2007 to estimate the effect of aminopenicillin, fluoroquinolone, trimethoprim/sulfamethoxazole, and tetracycline usage on resistance of Escherichia coli to drugs within these classes. We also quantified the effect of fluoroquinolone and macrolide/lincosamide usage on resistance of methicillin-resistant Staphylococcus aureus (MRSA) to ciprofloxacin and clindamycin (which has a similar mode of action to macrolides), respectively.

RESULTS

Prevalence of resistant Escherichia coli was significantly correlated with lagged (by 1 month) antibiotic prescriptions for aminopenicillins (0.22, P = .03) and fluoroquinolones (0.24, P = .02), which are highly prescribed, but was uncorrelated to antibiotic classes with lower prescription levels. Fluoroquinolone prescriptions were also significantly correlated with a 1-month lag with the prevalence of ciprofloxacin-resistant MRSA (0.23, P = .03).

CONCLUSIONS

Large-scale usage of antibiotics can generate seasonal patterns of resistance that fluctuate on a short time scale with changes in antibiotic retail sales, suggesting that use of antibiotics in the winter could have a significant effect on resistance. In addition, the strong correlation between community use of antibiotics and resistance isolated in the hospital indicates that restrictions imposed at the hospital level are unlikely to be effective unless coordinated with campaigns to reduce unnecessary antibiotic use at the community level.

Duration and cessation of antimicrobial treatment

Shortening the duration of antimicrobial therapy is an important strategy for optimizing patient care and reducing the spread of antimicrobial resistance. It is best used in the context of an overall approach to infection management that includes a focus on selecting the right initial drug and dosing regimen for empiric therapy, and de-escalation to a more narrowly focused drug regimen (or termination) based on subsequent culture results and clinical data. In addition to reducing resistance, other potential benefits of shorter antimicrobial courses include lowered antimicrobial costs, reduced risk of superinfections (including Clostridium difficile-associated diarrhea), reduced risk of antimicrobial-related organ toxicity, and improved drug compliance. There have been relatively few randomized clinical trials that study the optimal treatment durations for such serious infections as pneumonia (community- and healthcare/hospital-acquired), complicated intra-abdominal infection, and catheter-related bloodstream infection (CRBSI). Nonetheless, a growing number of studies have explored the possibilities of reducing the duration of antimicrobial therapy for at least certain patients with these infections, under certain circumstances. Professional organizations have compiled these data and used them to develop clinical practice guidelines to aid clinicians in choosing optimal treatment durations for individual patients. Many patients with hospital-acquired pneumonia, ventilator-associated pneumonia, or healthcare-associated pneumonia can be treated for 7-8 days, while 4-7 days and 14-day treatment durations may suffice for many patients with complicated intra-abdominal infections and uncomplicated CRBSI, respectively. This article first provides a general background on the rationale and data supporting shortened courses of antimicrobial therapy, before using 3 case studies to explore the practical implications of current knowledge and treatment guidelines when making decisions about treatment duration for individual patients with healthcare-associated pneumonia, complicated intra-abdominal infection, and CRBSI.

Implementation and outcomes of a hospital-wide computerised antimicrobial stewardship programme in a large medical centre in Taiwan

Antibiotic stewardship is important to address the problem of antimicrobial resistance, but a practical and sustainable strategy to provide stewardship in a large hospital setting is lacking. We developed a hospital-wide computerised antimicrobial approval system (HCAAS) to guide the use of antimicrobial agents in late 2004 in a 3500-bed medical centre in Taiwan. The objective of this study was to evaluate the impacts of HCAAS on the hospital from 2003 to 2009. Following HCAAS deployment, the gradients of consumption over time during the study period of third- and fourth-generation cephalosporins, fluoroquinolones and glycopeptides fell significantly, whilst that of carbapenems increased. The amount and expenditure of antimicrobial use did not increase with the overall healthcare-associated infection rate, and inpatient mortality rate remained stable with a slight decreasing trend. The rate of meticillin-resistant Staphylococcus aureus started to decline in 2002 and continued after HCAAS deployment. There was an increasing isolation of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae, presumably leading to the increased use of carbapenems. The isolation rate of Clostridium difficile from patients who developed diarrhoea after antimicrobial therapy did not change over the years, with a mean annual rate of 10.0% after the implementation of HCAAS. HCAAS along with strict infection control measures is necessary to reduce the spread of resistant organisms within the hospital. HCAAS is a sustainable system for providing antibiotic stewardship and exerts a positive impact on the hospital by reducing antimicrobial consumption and expenditure whilst not compromising healthcare quality.

The global need for effective antibiotics: challenges and recent advances

The emerging problem of antibiotic resistance is a serious threat to global public health. The situation is aggravated by a substantial decline in the research and development of antibacterial agents. Hence, very few new antibacterial classes are brought to market when older classes lose their efficacy. There has been renewed and growing attention within policy groups to: (i) address the problem; (ii) discuss incentives for the development of urgently needed new treatments; (iii) preserve the efficacy of existing therapeutic options. We briefly review the basic principles of antibiotic resistance, and contrast the increasing resistance to the dwindling antibacterial 'pipeline'. We also highlight some recent policy initiatives aiming to secure the future need of effective antibiotics.

Correlation between antibiotic use and changes in susceptibility patterns of Pseudomonas aeruginosa in a medical-surgical intensive care unit

Context:

Multiple surveillance programmes have reported a decline in antibiotic susceptibility of P. aeruginosa.

Aim:

Our study aimed to study the relationship between the use of antipseudomonal drugs and the development of resistance of P. aerogenosa to these drugs.

Setting and Design:

Our study is retrospective. It was conducted in a medical surgical intensive care unit during a five-year period (January 1^st, 1999 to December 31, 2003), which was divided into 20 quarters. We had monitored the use of antipseudomonal agents and the resistance rates of P. aeruginosa to these drugs.

Statistical Methods:

The associations between use and resistance were quantified using non-partial and partial correlation coefficients according to Pearson and Spearman.

Results:

Over the study period, the most frequently used antipseudomonal agent was Imipenem (152 ± 46 DDD/1000 patients-day) and the resistance rate of P. aeruginosa to Imipenem was 44.3 ± 9.5% (range, 30 and 60%). In addition, Imipenem use correlated significantly with development of resistance to Imipenem in the same (P < 0.05) and in the following quarter (P < 0.05); and Ciprofloxacin use correlated significantly with resistance to Ciprofloxacin in the following quarter (P < 0.05). However, use of Ceftazidime or Amikacine had no apparent association with development of resistance.

Conclusion:

We conclude that the extensive use of imipenem or ciprofloxacin in intensive care units may lead to the emergence of imipenem- and ciprofloxacin-resistant strains of P. aeruginosa and that antibiotic prescription policy has a significant impact on P. aeruginosa resistance rates in an intensive care unit.

Tazobactam/piperacillin for moderate-to-severe pneumonia in patients with risk for aspiration: comparison with imipenem/cilastatin

BACKGROUND

Treatment of aspiration pneumonia is becoming an important issue due to aging of populations worldwide. Effectiveness of tazobactam/piperacillin (TAZ/PIPC) in aspiration pneumonia is not clear.

PURPOSE

To compare clinical efficacy between TAZ/PIPC (1:4 compound) and imipenem/cilastatin (IPM/CS) in patients with moderate-to-severe aspiration pneumonia.

PATIENTS AND METHODS

In this open-label, randomized study either TAZ/PIPC 5 g or IPM/CS 1 g was intravenously administered every 12 h to patients with moderate-to-severe community-acquired aspiration pneumonia or nursing home-acquired pneumonia with risk for aspiration pneumonia for average 11 days. The primary outcome was clinical response rate at the end of treatment (EOT) in validated per-protocol (VPP) population. Secondary outcomes were clinical response during treatment (days 4 and 7) and at the end of study (EOS) in VPP population, and survival at day 30 in modified intention-to-treat (MITT) population.

RESULTS

There was no difference between the groups in primary or secondary outcome. However, significantly faster improvement as measured by axillary temperature (p < 0.05) and WBC count (p = 0.01) was observed under TAZ/PIPC treatment. In patients with gram-positive bacterial infection, TAZ/PIPC was more effective at EOT in VPP population (p = 0.03).

CONCLUSION

TAZ/PIPC is as effective and safe as IPM/CS in the treatment of moderate- to-severe aspiration pneumonia.

Previous ciprofloxacin exposure is associated with resistance to beta-lactam antibiotics in subsequent Pseudomonas aeruginosa bacteremic isolates

BACKGROUND

Pseudomonas aeruginosa cross-resistance to ceftazidime, imipenem, meropenem, piperacillin, and fluoroquinoles has been shown in experimental studies, but information regarding its impact in the clinical setting is scarce and inconsistent. The aim of this study was to assess whether previous exposure to ciprofloxacin influences on the sensitivity of those antibiotics in subsequent P aeruginosa bacteremic isolates.

METHODS

Patients with P aeruginosa bacteremia were recorded from a blood culture surveillance program (1997-2007). Demographic characteristics, underlying diseases, setting of the infection, source of infection, previous antibiotic exposure, and antibiotic sensitivity were analyzed.

RESULTS

We studied 572 cases of P aeruginosa bacteremia. There were 327 men (57.2%), and the mean age was 61.2 +/- 18 years. The bacteremia was nosocomial in 62.4% of episodes. Resistance rates of P aeruginosa isolates were 15.5% for ceftazidime, 16.7% for imipenem, 11.2% for meropenem, 12.3% for piperacillin-tazobactam, and 23.1% for ciprofloxacin. Exposure to ciprofloxacin during the previous 30 days was an independent predictor of resistance to ceftazidime (odds ratio [OR], 3; 95% confidence interval [CI]: 1.7-5.3; P < .001), imipenem (OR, 2; 95% CI: 1.1-3.7; P = .02), meropenem (OR, 2.7; 95% CI: 1.4-5.3; P = .004), piperacillin-tazobactam (OR, 2.4; 95% CI: 1.3-4.7; P = .007), ciprofloxacin (OR, 2.9; 95% CI: 1.7-4.9; P < .001), and multidrug resistance (OR, 2.5; 95% CI: 1.2-5.2; P = .02).

CONCLUSION

P aeruginosa bacteremic isolates from patients who have been exposed to ciprofloxacin during the 30 days prior to the development of bacteremia have an increased risk of being resistant to ceftazidime, imipenem, meropenem, piperacillin-tazobactam, or ciprofloxacin and to have multidrug resistance.

Intra-abdominal infections: etiology, epidemiology, microbiological diagnosis and antibiotic resistance

Intra-abdominal infections (IAIs) are commonly encountered in clinical practice. The etiology of these infections, often polymicrobial in nature, can be variable and usually includes organisms derived from the gut microbiota. in community-acquired IAIs enterobacteria predominate (mostly Escherichia coli) in combination with anaerobes (mostly Bacteroides fragilis). In nosocomial IAIs, which can complicate abdominal surgery, other pathogens can also play a role, such as Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus spp. and Candida spp. Diagnostic microbiology of IAIs is complex and plays a relevant role, especially in some situations (e.g. presence of foreign bodies, potential presence of resistant or uncommon pathogens, nosocomial infections in subjects with risk factors). Antibiotic resistance issues are currently encountered in most pathogenic species causing IAIs. Resistance affects all major classes of antimicrobial agents, often involving multiple classes and resulting in complex resistance phenotypes for which only a very limited number of drugs remain active.

Carbapenems and subsequent multiresistant bloodstream infection: does treatment duration matter?

It has been proposed that initial empirical broad-spectrum antibiotic therapy will result in better clinical outcomes and that shorter courses will reduce the 'collateral damage' of promoting antibiotic resistance. There are few data from Intensive Care Units (ICUs) that support this latter conclusion. A prospective observational study was undertaken at the National University Hospital, Singapore, to examine the relationship between duration of carbapenem therapy and subsequent nosocomial multidrug-resistant (MDR) bloodstream infection (BSI). Over a 2-year period, 415 ICU patients receiving empirical carbapenem therapy were prospectively followed. MDR BSI occurred on 35 occasions in 31 patients, comprising 21 carbapenem-resistant Acinetobacter baumannii, 3 carbapenem-resistant Pseudomonas aeruginosa and 11 meticillin-resistant Staphylococcus aureus (MRSA). There was no difference in the duration of carbapenems for those who developed MDR BSI compared with those who did not [median duration 8 days (range 3-23 days) vs. 9 days (range 3-59 days); P=0.78]. On multivariate analysis using the Cox proportional hazard model the hazard ratio was 0.935 (P=0.070). In this cohort of critically ill patients, a shorter duration of carbapenem therapy was not shown to protect against subsequent development of MDR BSI. Strategies that depend primarily on reducing broad-spectrum antibiotic duration may be inadequate in preventing the emergence of MDR organisms.

Current treatment of pseudomonal infections in the elderly

Pseudomonas aeruginosa infections have emerged as a major infectious disease threat in recent decades as a result of the significant mortality of pseudomonal pneumonia and bacteraemia, and the evolving resistance exhibited by the pathogen to numerous antibacterials. Pseudomonas possesses a large genome; thus, the pathogen is environmentally adaptable, metabolically flexible, able to overcome antibacterial pressure by selecting for resistant strains and even able to accumulate resistance mechanisms, leading to multidrug resistance (MDR), an increasingly recognized therapeutic challenge. In fact, most research currently does not focus on maximizing the efficacy of available antibacterials; rather, it focuses on maximizing their ecological safety. The elderly population may be particularly prone to pseudomonal infection as a result of increased co-morbidities (such as diabetes mellitus and structural lung disease), the presence of invasive devices such as urinary catheters and feeding tubes, polypharmacy that includes antibacterials, and immune compromise related to age. However, age per se, as well as residence in nursing homes, may not predispose individuals to an increased risk for pseudomonal infection. On the other hand, age has been repeatedly outlined as a risk factor for MDR pseudomonal infections. The severity of pseudomonal infections necessitates prompt administration of appropriate antibacterials upon suspicion. Progress has been made in recognizing risk factors for P. aeruginosa infections both in hospitalized and community-residing patients. Antimicrobial therapy may be instituted as a combination or monotherapy: the debate cannot be definitively resolved since the available data are extracted from studies with varying targeted populations and varying definitions of response, adequacy and MDR. Empirical combination therapy maximizes the chances of bacterial coverage and exerts a lower resistance selection pressure. Although associated with increased percentages of adverse events, mainly as a result of the included aminoglycosides, empirical combination therapy seems a reasonable choice. Upon confirmation of Pseudomonas as the causative agent and awareness of its susceptibility profile, monotherapy is advocated by many, but not all, experts. Infections involving MDR strains can be treated with colistin, which has adequate efficacy and few renal adverse events, or doripenem. In the elderly, in addition to making dose modifications that are needed because of loss of renal function, the prescriber should be more cautious about the use of aminoglycoside-containing regimens, possibly replacing them with a combination of quinolone and a beta-lactam, notwithstanding the possible increased pressure for selection of resistance with the latter combination.

Determinação da resistência antimicrobiana associada em isolados clínicos de Staphylococcus aureus e Pseudomonas aeruginosa em um hospital público de Goiânia, Estado de Goiás

Este estudo avaliou a resistência antimicrobiana associada de Pseudomonas aeruginosa e Staphylococcus aureus a um agente antimicrobiano com outras drogas. A resistência antimicrobiana associada foi calculada através do risco relativo. Houve uma relação óbvia entre resistência à oxacilina e a outros agentes antimicrobianos entre os isolados de Staphylococcus aureus resistentes à oxacilina (68,5%) superior a 32%, com exceção da linezolida (6,7%). Resistência associada pronunciada entre drogas foi observada para isolados de Pseudomonas aeruginosa, particularmente entre ciprofloxacina e os carbapenens (59,6% a 60,7%), entre aminoglicosídeos e carbapenens (66,3% a 67,7%) e os demais β-lactâmicos (52,3% a 85,8%). O presente trabalho enfatiza a importância da cultura diagnóstica e do teste de suscetibilidade na seleção de um correto agente antimicrobiano com relação ao impacto clínico no aumento da multirresistência e na seleção de resistência antimicrobiana associada.

The evolution of drug-resistant microorganisms in patients with prolonged mechanical ventilation

BACKGROUND

Patients requiring prolonged mechanical ventilation (PMV) tend to become reservoirs of antimicrobial resistance. We assessed antimicrobial-resistant microorganisms in the respiratory tracts of patients receiving PMV.

METHODS

Over a 6-month period, the microorganisms from tracheal aspirates of PMV patients with lower airway infection were analyzed.

RESULTS

Antimicrobial use was greatest during the acute critical stage of respiratory failure. Antimicrobial resistance in Pseudomonas aeruginosa and Klebsiella pneumoniae peaked during the fourth to 15th weeks of PMV. Methicillin-resistant Staphylococcus aureus (MRSA) developed rapidly during the first 3 weeks of PMV. The acquisition of multidrug-resistant P aeruginosa and MRSA were significantly correlated with previous exposure to ceftazidime (odds ratio [OR] = 121.3 and 72.5; P = .01 and .01, respectively). The rise of multidrug-resistant Acinetobacter baumannii was significantly correlated with previous exposure to piperacillin/tazobactam (OR = 26.81; P = .02) and imipenem (OR = 16.91; P = .03). Using univariate and multivariate logistic regression models, the lower respiratory tract infections with multidrug-resistant microorganisms were independently associated with increased 6-month mortality (OR = 3.41; P < .01).

CONCLUSION

In patients receiving PMV, lower respiratory tract infection with multidrug-resistant microorganisms is common and is associated with higher mortality.

Spread of Metallo-β-lactamases: screening reveals the presence of aBLA SPM-1 gene in hospital sewage in southern Brazil

Of 396 Pseudomonas aeruginosa strains isolated from hospital sewage, the blaSPM-1 gene was confirmed in nine. This is the first report of environmental P. aeruginosa strains carrying the blaSPM-1 gene in Brazil. The carbapenem resistance, already disseminated among clinical isolates, has been detected among environmental isolates.

Bad bugs, no drugs: no ESKAPE! An update from the Infectious Diseases Society of America

The Infectious Diseases Society of America (IDSA) continues to view with concern the lean pipeline for novel therapeutics to treat drug-resistant infections, especially those caused by gram-negative pathogens. Infections now occur that are resistant to all current antibacterial options. Although the IDSA is encouraged by the prospect of success for some agents currently in preclinical development, there is an urgent, immediate need for new agents with activity against these panresistant organisms. There is no evidence that this need will be met in the foreseeable future. Furthermore, we remain concerned that the infrastructure for discovering and developing new antibacterials continues to stagnate, thereby risking the future pipeline of antibacterial drugs. The IDSA proposed solutions in its 2004 policy report, "Bad Bugs, No Drugs: As Antibiotic R&D Stagnates, a Public Health Crisis Brews," and recently issued a "Call to Action" to provide an update on the scope of the problem and the proposed solutions. A primary objective of these periodic reports is to encourage a community and legislative response to establish greater financial parity between the antimicrobial development and the development of other drugs. Although recent actions of the Food and Drug Administration and the 110th US Congress present a glimmer of hope, significant uncertainly remains. Now, more than ever, it is essential to create a robust and sustainable antibacterial research and development infrastructure--one that can respond to current antibacterial resistance now and anticipate evolving resistance. This challenge requires that industry, academia, the National Institutes of Health, the Food and Drug Administration, the Centers for Disease Control and Prevention, the US Department of Defense, and the new Biomedical Advanced Research and Development Authority at the Department of Health and Human Services work productively together. This report provides an update on potentially effective antibacterial drugs in the late-stage development pipeline, in the hope of encouraging such collaborative action.

Correlation between antibiotic consumption and bacterial resistance as quality indicator of proper use of these drugs in inpatients

Background/Aim. Antibiotics are the most frequently used medications in Serbian hospitalized patients. Information about antibiotic utilization and sensitivity among inpatients in Serbia is scanty, and there are no available publications on the topic. The aim of this study was to investigate the correlation between antibiotic use and bacterial resistance in the Clinical Center Nis, one of the biggest hospitals in Serbia. Methods. The data on antibiotics use in inpatients were obtained from the database of the Department of Pharmacotherapy and expressed as defined daily doses per 100 bed-days (DBD), during 2003-2007. Bacterial resistances were given as percentages of resistant isolates. Results. During the investigation period, the overall consumption of antibiotics had a significant decrease in 2007, by 22.99% (62.23 : 47.92 DBD; p < 0.05). The most frequently used antibiotics were cephalosporins, followed by penicillin's, aminoglycosides and quinolones. Hospital aminoglycosides consumption was reduced in 2007 to 59.9% (13.4 : 5.53 DBD) while the resistance to amikacin was reduced from 40.88% to 32.1%. However, utilization of ciprofloxacin had a significant increase in 2007 (120.7%). There was an alarming increase in the level of resistance to ciprofloxacin in our hospital (from 13.5% to 28.3 % in Escherichia coli and from 11.1 to 30.09% in Proteus mirabilis). Reduction of E coli resistant to amoxicillin+clavulanic acid correlated significantly with their utilization, while the resistance for all isolates decreased from 52.16% to 24.40%. Conclusions. These results confirm an association between the use of antibiotics and the prevalence of resistance. This methodology could provide good quality indicators of rational drug use and serve for local monitoring of antibiotics use and resistance, as well as for external comparison.

Affinity of Tomopenem (CS-023) for penicillin-binding proteins in Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa

Tomopenem (formerly CS-023), a novel 1beta-methylcarbapenem, exhibited high affinity for penicillin-binding protein (PBP) 2 in Staphylococcus aureus, PBP 2 in Escherichia coli, and PBPs 2 and 3 in Pseudomonas aeruginosa, which are considered major lethal targets. Morphologically, tomopenem induced spherical forms in E. coli and short filamentation with bulges in P. aeruginosa, which correlated with the drug's PBP profiles. The potential of resistance of these bacteria to tomopenem was comparable to that to imipenem.

Clinical review: balancing the therapeutic, safety, and economic issues underlying effective antipseudomonal carbapenem use

Antipseudomonal carbapenems have played a useful role in our antimicrobial armamentarium for 20 years. However, a review of their use during that period creates concern that their clinical effectiveness is critically dependent on attainment of an appropriate dosing range. Unfortunately, adequate carbapenem dosing is missed for many reasons, including benefit/risk misconceptions, a narrow therapeutic window for imipenem and meropenem (due to an increased rate of seizures at higher doses), increasingly resistant pathogens requiring higher doses than are typically given, and cost containment issues that may limit their use. To improve the use of carbapenems, several initiatives should be considered: increase awareness about appropriate treatment with carbapenems across hospital departments; determine optimal dosing regimens for settings where multidrug resistant organisms are more likely encountered; use of, or combination with, an alternative antimicrobial agent having more favorable pharmacokinetic, pharmacodynamic, or adverse event profile; and administer a newer carbapenem with lower propensity for resistance development (for example, reduced expression of efflux pumps or greater stability against carbapenemases).

Eradication of helicobacter pylori to prevent gastroduodenal diseases: hitting more than one bird with the same stone

Helicobacter pylori (H. pylori) are gram-negative bacteria that selectively colonizes the gastric mucosa. The prevalence of H. pylori infection varies from 20 to 50% in industrialized countries to over 80% in developing countries. The infection may persist lifelong without specific treatment. Prolonged infection and inflammation due to bacterial virulence and host genetic factors will lead to chronic gastritis. A certain portion of infected patients then develop more severe pathologies such as peptic ulcer (10-15%), gastric cancer (1%), and mucosa-associated lymphoid tissue lymphoma (50.01%). Although the majority of infected patients remain asymptomatic, much of the evidence has shown that eradication of H. pylori infection can reduce the recurrence of peptic ulcer and benefit a substantial portion of patients with nonulcer dyspepsia. Though controversial in population-based clinical trials, several cost-effectiveness analyses also reveal that H. pylori eradication is cost effective in the primary prevention of gastric cancer. Therefore, the discovery of H. pylori offers the chance to prevent several gastroduodenal diseases by means of their eradication. In other words, gastroenterologists could hit more than one bird with one stone. However, there are concerns regarding application of a 'test and treat' strategy in the general population. In this review, we will focus on current evidence of H. pylori eradication in the primary and secondary prophylaxis of gastric cancer and peptic ulcer disease.

Differential correlation between rates of antimicrobial drug consumption and prevalence of antimicrobial resistance in a tertiary care hospital in Greece

OBJECTIVE

To investigate whether there is a correlation between the rates of antimicrobial drug consumption in hospital departments and the prevalence of antimicrobial resistance among clinically important bacteria recovered in the hospital.

DESIGN

Retrospective study.

SETTING

Tertiary care hospital in Greece.

METHODS

Data on antimicrobial consumption (from January 2001 through December 2004) were expressed as defined daily doses per 100 bed-days. The prevalence of antimicrobial resistance among isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecium recovered during the same time period were calculated by the microbiology department. We then performed the following analyses: (1) a comparison of the consumption rates for different antimicrobial groups in individual hospital departments, (2) a comparison of the prevalence of resistance to different antimicrobials, and (3) a correlation analysis of antimicrobial consumption rates and the prevalence of antimicrobial resistance.

RESULTS

The rates of antimicrobial consumption and the prevalence of resistance varied substantially among the hospital's departments. The annual rate of consumption for carbapenems correlated with the rate of consumption for glycopeptides and third-generation cephalosporins (P < .05). Among P. aeruginosa isolates, the prevalence of imipenem resistance correlated with the prevalence of resistance to amikacin, ciprofloxacin, and ceftazidime (P < .05). The rate of carbapenem consumption correlated with the prevalence of imipenem resistance among P. aeruginosa and A. baumannii isolates (P < .05). The rate of aminoglycoside consumption correlated with the prevalence of amikacin resistance among P. aeruginosa, K. pneumoniae, and E. coli isolates (P < .05). However, the rate of consumption for fluoroquinolones and glycopeptides had no correlation with the prevalence of ciprofloxacin resistance among gram-negative bacteria or vancomycin resistance among E. faecium isolates.

CONCLUSIONS

These data are suggestive of a differential relationship between antimicrobial consumption and the prevalence of antimicrobial resistance among various species and for various antimicrobial agents. These findings may help to optimize antimicrobial prescription policies in the hospital, especially in departments that have both high rates of antimicrobial consumption and a high prevalence of antimicrobial resistance.

Asia-Pacific consensus guidelines on gastric cancer prevention

BACKGROUND AND AIM

Gastric cancer is a major health burden in the Asia-Pacific region but consensus on prevention strategies has been lacking. We aimed to critically evaluate strategies for preventing gastric cancer.

METHODS

A multidisciplinary group developed consensus statements using a Delphi approach. Relevant data were presented, and the quality of evidence, strength of recommendation, and level of consensus were graded.

RESULTS

Helicobacter pylori infection is a necessary but not sufficient causal factor for non-cardia gastric adenocarcinoma. A high intake of salt is strongly associated with gastric cancer. Fresh fruits and vegetables are protective but the use of vitamins and other dietary supplements does not prevent gastric cancer. Host-bacterial interaction in H. pylori infection results in different patterns of gastritis and differences in gastric acid secretion which determine disease outcome. A positive family history of gastric cancer is an important risk factor. Low serum pepsinogens reflect gastric atrophy and may be useful as a marker to identify populations at high risk for gastric cancer. H. pylori screening and treatment is a recommended gastric cancer risk reduction strategy in high-risk populations. H. pylori screening and treatment is most effective before atrophic gastritis has developed. It does not exclude the existing practice of gastric cancer surveillance in high-risk populations. In populations at low risk for gastric cancer, H. pylori screening is not recommended. First-line treatment of H. pylori infection should be in accordance with national treatment guidelines.

CONCLUSION

A strategy of H. pylori screening and eradication in high-risk populations will probably reduce gastric cancer incidence, and based on current evidence is recommended by consensus.

Carbapenems: a potent class of antibiotics

The purpose of this review is to assess the relative strengths and weaknesses of individual members of the carbapenem class of antibiotics. Clinical trials and review articles were identified from a Medline search (1979 - July 2006), in addition to, reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and the 12th International Congress on Infectious Disease, and package inserts. Articles in English were reviewed, with emphasis on those containing efficacy or safety data. Carbapenems bind to critical penicillin-binding proteins, disrupting the growth and structural integrity of bacterial cell walls. They provide enhanced anaerobic and Gram-negative coverage as compared with other beta-lactams and their stability against extended-spectrum beta-lactamases (ESBLs) makes them an effective treatment option. The most common adverse effects are infusion-site complications and gastrointestinal distress. Ertapenem has limited efficacy against non-fermenting, Gram-negative bacteria, restricting its use to community-acquired infections. Imipenem is slightly more effective against Gram-positive organisms and meropenem slightly more effective against Gram-negative organisms. However, both have broad-spectrum activity, including non-fermenting, Gram-negative bacteria. Among non-fermenting, Gram-negatives, resistance to imipenem in particular is increasing. Doripenem is in late-stage clinical development and combines the broad-spectrum coverage of imipenem and meropenem, and more potent activity against Pseudomonas aeruginosa. Due to the increasing challenges represented by ESBLs and multi-drug resistant organisms, the carbapenems are assuming a greater role in the treatment of serious infections. Imipenem and meropenem are presently available and have been shown to be effective against nosocomial infections. Doripenem is an investigational carbapenem that has completed Phase III clinical trials and that has the potential to improve on this efficacy and minimize the emergence of resistance to the carbapenem class.

Relationship between rates of antimicrobial consumption and the incidence of antimicrobial resistance in Staphylococcus aureus and Pseudomonas aeruginosa isolates from 47 French hospitals

OBJECTIVE

To investigate relationships between rates of antimicrobial consumption and the incidence of antimicrobial resistance in Staphylococcus aureus and Pseudomonas aeruginosa isolates from hospitals.

METHODS

We conducted an observational study that used retrospective data from 2002 and linear regression to model relationships. Hospitals were asked to collect data on consecutive S. aureus and P. aeruginosa isolates, consumption rates for antibiotics (ie, anti-infectives for systemic use as defined by Anatomical Therapeutic Chemical class J01), and hospital characteristics, including infection control policies. Rates of methicillin resistance in S. aureus and rates of ceftazidime and ciprofloxacin resistance in P. aeruginosa were expressed as the percentage of isolates that were nonsusceptible (ie, either resistant or intermediately susceptible) and as the incidence of nonsuceptible isolates (ie, the number of nonsuceptible isolates recovered per 1,000 patient-days). The rate of antimicrobial consumption was expressed as the number of defined daily doses per 1,000 patient-days.

SETTING

Data were obtained from 47 French hospitals, and a total of 12,188 S. aureus isolates and 6,370 P. aeruginosa isolates were tested.

RESULTS

In the multivariate analysis, fewer antimicrobials showed a significant association between the consumption rate and the percentage of isolates that were resistant than an association between the consumption rate and the incidence of resistance. The overall rate of antibiotic consumption, not including the antibiotics used to treat methicillin-resistant S. aureus infection, explained 13% of the variance between hospitals in the incidence of methicillin resistance among S. aureus isolates. The incidence of methicillin resistance in S. aureus isolates increased with the use of ciprofloxacin and levofloxacin and with the percentage of the hospital's beds located in intensive care units (adjusted multivariate coefficient of determination [aR(2)], 0.30). For P. aeruginosa, the incidence of ceftazidime resistance was greater in hospitals with higher consumption rates for ceftazidime, levofloxacin, and gentamicin (aR(2), 0.37). The incidence of ciprofloxacin resistance increased with the use of fluoroquinolones and with the percentage of a hospital's beds located in intensive care ( aR(2), 0.28).

CONCLUSIONS

A statistically significant relationship existed between the rate of fluoroquinolone use and the rate of antimicrobial resistance among S. aureus and P. aeruginosa isolates. The incidence of resistant isolates showed a stronger association with the rate of antimicrobial use than did the percentage of isolates with resistance.

Modified guidelines impact on antibiotic use and costs: duration of treatment for pneumonia in a neurosurgical ICU is reduced

OBJECTIVES

To evaluate the impact of an intervention to reduce the duration of antibiotic treatment for pneumonia in a neurosurgical intensive care unit (ICU). The usage of antibiotics and the resultant costs were examined using interrupted time series analysis while resistance and device-associated infection rates are also described.

METHODS

In January 2004, revised guidelines for the use of antibiotics were implemented. As a consequence of this, the duration of antibiotic therapy for nosocomial pneumonia was reduced from 14 to 7 days, while for community-acquired pneumonia the period fell from 10 to 5 days. The effect on the antibiotic use density [AD; expressed as defined daily doses (DDD) per 1000 patient days (pd)] was calculated by segmented regression analysis of interrupted time series for the 24 months prior to (2002 and 2003) and after the intervention (2004 and 2005).

RESULTS

The intervention was associated with a significant decrease in total AD from 949.8 to 626.7 DDD/1000 pd after the intervention. This was mainly due to reduced consumption of second-generation cephalosporins (-100.6 DDD/1000 pd), imidazoles (- 100.3 DDD/1000 pd), carbapenems (-33.3 DDD/1000 pd), penicillins with beta-lactamase inhibitor (-33.5 DDD/1000 pd) and glycopeptides (-30.2 DDD/1000 pd). Glycopeptide reduction might be associated with a significant decrease in the proportion of methicillin-resistant Staphylococcus aureus (8.4% before and 2.9% after the intervention). Similarly, total antibiotic costs/pd (Euro) showed a significant decrease from 13.16 Euro/pd before to 7.31 euro/pd after the intervention. This is a saving of 5.85 Euro/pd. The incidence of patients dying with pneumonia did not change significantly.

CONCLUSIONS

The most conservative estimate of segmented regression analysis over a 48 month period showed that halving the duration of treatment for pneumonia results in a reduction of over 30% in antibiotic consumption and costs. Because respiratory infections are most common in ICU patients, interventions targeting a reduction in the duration of treatment of pneumonia might be extremely worthwhile.

Increase of imipenem resistance among Pseudomonas aeruginosa isolates from a Polish paediatric hospital (1993-2002)

Analysis of the in vitro activity of imipenem and 13 other antibiotics against 2485 Pseudomonas aeruginosa isolates obtained from clinical specimens from children hospitalized during 1993-2002 was performed. In 2002, the percentage of P. aeruginosa isolates susceptible to all tested antibiotics, with the exception of imipenem, increased or remained on nearly the same level as in 1993. An increase of resistance to imipenem from 4.3% to 18.3% was observed. The MIC(90) value of imipenem increased from 2mg/L to 16 mg/L. Simultaneously, a four-fold increase of the usage of carbapenems imipenem and meropenem in the hospital was noted. In 2000-2001, a high incidence of imipenem-resistant strains was observed. The imipenem-resistant P. aeruginosa strains of serotype O6 from the general surgery ward and serotype O11 from the intensive care unit were shown to be clonally related by the pulsed-field gel electrophoresis method.

[Antibiotic prescribing policy of the Republic Health Insurance Fund of Montenegro in the period 2000 - 2004: effects of drug utilization reform strategy]

INTRODUCTION

Monitoring of antibiotic prescribing promotes rational use of these drugs, reduces costs and slows down the progress of resistance. The objective of present study was to analyze the effects of drug utilization reform strategy realized by the Republic Health Insurance Fund of Montenegro, during the period 2000-2004.

MATERIAL AND METHODS

This before-after comparative pharmacoepidemiological study comprised a sample of 100% prescription only antibiotics available in public pharmacies during the period 2000 - 2004. The drug use was calculated using ATC/DDD methodology and Wilcoxon's test for matched pairs was used in order to calculate the statistical significance of difference.

RESULTS

Antibiotic prescribing was approximately lower by 12% in 2004 in regard to 2000 (12.80 vs. 14.57 DDDs, p > 0.05). The participation of this pharmacotherapeutic group in the total drug dispensing has remained almost equal (approximately 8%). The highest increase in prescribing was established for macrolides (1.05 vs. 1.64 DDDs, 59%); penicillins were also prescribed more frequently (6.41 vs. 6.56 DDDs, 2%), but other subgroups were prescribed less frequently: cephalosporins--(23%) (3.11 vs. 2.43 DDDs) and quinolones--(63%) (1.10 vs. 0.47 DDDs).

CONCLUSION

The drug utilization reform strategy showed mostly positive effects on antibiotic prescribing during the period 2000 - 2004. Further educational activities are necessary in order to establish more rational approach to prescribing and utilization of antibiotics.

Comparative in vivo efficacy of meropenem, imipenem, and cefepime against Pseudomonas aeruginosa expressing MexA-MexB-OprM efflux pumps

To identify the optimal pharmacodynamic exposures of meropenem, imipenem, and cefepime, and the emergence of resistance in vivo for Pseudomonas aeruginosa overexpressing MexA-MexB-OprM efflux pumps, we used the murine thigh model. Mice were challenged with P. aeruginosa isolates: PAO1 (K767 wild type), K767+ (MexA-MexB-OprM efflux mutant), and DeltaK767 (knockout strain). Efficacy (Delta log colony-forming unit [CFU]) was determined at various exposures of %T > MIC at both standard (10(5) CFU/thigh) and high (10(7) CFU/thigh) inoculums. At 10(5) CFU/thigh, meropenem and imipenem produced a maximal activity against PAO1 (-2.82, -1.88) and K767+ (-2.24, -2.68) at 40%T > MIC; cefepime at 70%T > MIC produced a comparable kill (-2.74 and -2.19, respectively). Similar magnitudes of kill were observed at the 10(7) inocula. Except for DeltaK767 with cefepime, no development of resistance emerged at various %T > MIC. All agents exhibited reduced activity against DeltaK767. DeltaK767 cefepime-resistant strains were isolated up to 100%T > MIC. The overexpression of MexA-MexB-OprM efflux pumps did not result in the loss of efficacy of the antibiotics tested regardless of the amount of bacterial inocula; however, their presence also did not lead to increased selection for resistance. The effects of efflux mechanisms on beta-lactam agents in vivo warrant further research.

Antibiotic resistance in long-term acute care hospitals: the perfect storm

OBJECTIVE

To examine bacterial antibiotic resistance and antibiotic use patterns in long-term acute care hospitals (LTACHs) and to evaluate effects of antibiotic use and other hospital-level variables on the prevalence of antibiotic resistance.

DESIGN

Multihospital ecologic study.

METHODS

Antibiograms, antibiotic purchasing data, and demographic variables from 2002 and 2003 were obtained from 45 LTACHs. Multivariable regression models were constructed, controlling for other hospital-level variables, to evaluate the effects of antibiotic use on resistance for selected pathogens. Results of active surveillance in 2003 at one LTACH were available.

RESULTS

Among LTACHs, median prevalences of resistance for several antimicrobial-organism pairs were greater than the 90th percentile value for National Nosocomial Infections Surveillance system (NNIS) medical intensive care units (ICUs). The median prevalence of methicillin resistance among Staphylococcus aureus isolates was 84%. More than 60% of patients in one LTACH were infected or colonized with methicillin-resistant S. aureus and/or vancomycin-resistant Enterococcus at the time of admission. Antibiotic consumption in LTACHs was comparable to consumption in NNIS medical ICUs. In multivariable logistic regression modeling, the only significant association between antibiotic use and the prevalence of antibiotic resistance was for carbapenems and imipenem resistance among Pseudomonas aeruginosa isolates (odds ratio, 11.88 [95% confidence interval, 1.42-99.13]; P=.02).

CONCLUSIONS

The prevalence of antibiotic resistance among bacteria recovered from patients in LTACHs is extremely high. Although antibiotic use in LTACHs likely contributes to resistance prevalence for some antimicrobial-organism pairs, for the majority of such pairs, other variables, such as prior colonization with and horizontal transmission of antimicrobial-resistant pathogens, may be more important determinants. Further research on antibiotic resistance in LTACHs is needed, particularly with respect to determining optimal infection control practices in this environment.

Risk of emergence of Pseudomonas aeruginosa resistance to β-lactam antibiotics in intensive care units

OBJECTIVE

The emergence of Pseudomonas aeruginosa resistance to antimicrobial drugs is frequent in intensive care units and may be correlated with the use of some specific drugs. The purpose of our study was to identify a relationship between the use of various beta-lactam antibiotics and the emergence of resistance and to characterize the mechanism of resistance involved.

DESIGN

We conducted an open prospective study over a 3-yr period by including all patients in whom P. aeruginosa had been isolated from one or more specimens: bronchial aspiration, blood cultures, catheters, and urinary cultures.

SETTING

General intensive care unit.

PATIENTS

One hundred and thirty-two intensive care unit patients.

INTERVENTIONS

The antibiotics studied were amoxiclav, piperacillin-tazobactam, cefotaxime, ceftazidime, cefepim, and imipenem. The mechanisms of resistance studied were production of penicillinase or cephalosporinase, nonenzymatic mechanisms, and loss of porin OprD2. Analysis was performed using Cox proportional-hazard regression with time-dependant variables.

MEASUREMENTS AND MAIN RESULTS

Forty-two strains became resistant, 30 to one antibiotic, nine to two, and three to three, leading to the study of 57 resistant strains. Imipenem (hazard ratio 7.8; 95% confidence interval, 3.4-18.1), piperacillin-tazobactam (hazard ratio 3.9; 95% confidence interval, 1.3-11.9), and cefotaxim (hazard ratio 9.3; 95% confidence interval, 2.9-30.2) were strongly linked to the emergence of resistance. The use of imipenem (p<.0001) was associated with the loss of porin OprD2. Thirty-six strains from nine patients, assayed by pulsed-field gel electrophoresis, showed that for any one patient, all the strains were genetically related.

CONCLUSIONS

Our results show that there is a high risk of the emergence of drug resistance during treatment with cefotaxime, imipenem, and piperacillin-tazobactam. This has to be taken into account in the therapeutic choice and in the patient's surveillance.

Empiric broad-spectrum antibiotic therapy of nosocomial pneumonia in the intensive care unit: a prospective observational study

Introduction

Antibiotic de-escalation, which consists of the initial institution of empiric broad-spectrum antibiotics followed by antibiotic streamlining driven by microbiological documentation, is thought to provide maximum benefit for the individual patient, while reducing the selection pressure for resistance.

Methods

To assess a carbapenem-based de-escalating strategy in nosocomial pneumonia (NP), a prospective observational study was conducted in critically ill patients with NP treated empirically with imipenem ± aminoglycoside/glycopeptide in 24 intensive care units of Spanish general hospitals. Overall, 244 patients were assessable (91% with late-onset NP). The primary outcome was therapeutic success 7–9 days post therapy.

Results

Microbial identification – based on cultures of tracheal aspirates in 82% of patients, cultures of protected specimen brush in 33%, and cultures of bronchoalveolar lavage in 4% – was only available for 131 (54%) patients. Initial antibiotics were inadequate for 23 (9%) patients. Of the remaining patients, antibiotics were streamlined in 56 (23%) patients and remained unchanged in 14 (6%) patients based on microbiology data, in 38 (16%) patients despite microbiology data favouring de-escalation, and in 113 (46%) patients due to unknown aetiology. Overall, de-escalation was implemented in only 23% of patients with potentially multiresistant pathogens, compared with 68% of patients with the remaining pathogens (P < 0.001). Response rates were 53% for patients continuously treated with imipenem-based regimens and 50% for the de-escalated patients. Higher Acute Physiology, Age, and Chronic Health Evaluation II scores were associated with greater mortality, whereas adequate empiric antibiotic therapy protected against fatal outcomes. No increase of superinfection rates caused by emerging pathogens was observed. The costs associated with de-escalation were mainly dependent on the duration of hospitalization.

Conclusion

This study mainly highlights the current practice of a specific algorithm of de-escalation solely based on the available microbiological data, and highlights the barriers to using it more widely. In this setting, de-escalation was less likely to occur in the presence of potentially multiresistant pathogens. Prior antibiotic administration and the low use of bronchoscopic techniques may have influenced negatively the implementation of de-escalation. Optimization of de-escalation strategies for NP should rely on a correct choice of empiric antibiotics, on appropriate microbiological investigations, and on a balanced interpretation of microbiological and clinical data.

Comparison of piperacillin/tazobactam and imipenem/cilastatin, both in combination with tobramycin, administered every 6 h for treatment of nosocomial pneumonia

This randomized, double-blind, multicenter study compared the efficacy and safety of piperacillin/tazobactam (P/T) and imipenem/cilastatin (IMP), both in combination with an aminoglycoside, in hospitalized patients with acute nosocomial pneumonia (NP). Patients with acute NP, defined as pneumonia with symptoms > or = 48 h after admission or < or =7 days after hospital discharge, received infusions of 4 g/500 mg P/T or 500 mg/500 mg IMP every 6 h. Endpoints were clinical cure and microbiological response rates; pathogen eradication rates; length of hospital stay; hospital readmissions; and adverse events (AEs). Of 437 patients in the intent-to-treat population, 197 were efficacy evaluable. At test-of-cure, response rates were similar between groups. Within the efficacy evaluable population, 68% of P/T patients and 61% of IMP patients were clinically cured (P = 0.256). Microbiological responses for P/T and IMP patients were: eradication, 64% versus 59%; persistence, 29% versus 21%; relapse, 0% versus 5%; and superinfection, 7% versus 15%, respectively. Gram-positive isolates were eradicated in 83% of P/T patients and 75% of IMP patients; Gram-negative pathogens were eradicated in 72% of P/T patients and 77% of IMP patients. Treatment groups had similar number of mean hospital days, readmission rates, and frequency of AEs. This study showed that P/T administered four times per day was as safe and efficacious as IMP in treating hospitalized patients with NP.

Effect of systematic empiric treatment with imipenem on the bacterial ecology in a burns unit

This study took place over 18 months and was divided into three 6 month periods. During the first and third periods, the bacterial ecology of the unit was reviewed, including the observation of bacteria which were isolated and led us to prescribe general antimicrobial therapy, and record the subsequent antibiograms that became available. During the second 6 month period, any patient developing an infection due (or possibly due) to a "Gram negative" strain received imipenem (as beta lactam antimicrobial agent), usually combined with tobramycin. The comparison between bacteria and antibiograms isolated during the first and the third periods did not show any increase in multiple resistant bacteria or imipenem resistant strains, including methicillin resistant Staphylococcus aureus (MRSA). During the third period, in comparison with the first, the number of Pseudomonas aeruginosa and Acinetobacter strains was lower; however, the number of Enterobacter and Klebsiella had increased. There was an increase of overall resistance to ticarcillin, but there was no increase in resistance to the other antimicrobials concerned in the study. Therefore, we concluded that wide use of imipenem did not impair the bacterial ecology of the unit, if used with precautions such as high dose regimen, de-escalation, and both pharmacokinetics and ecology monitoring.

Treatment and control of severe infections caused by multiresistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the leading causes of nosocomial infections. Severe infections, such as pneumonia or bacteraemia, are associated with high mortality rates and are often difficult to treat, as the repertoire of useful anti-pseudomonal agents is limited (some beta-lactams, fluoroquinolones and aminoglycosides, and the polymyxins as last-resort drugs); moreover, P. aeruginosa exhibits remarkable ability to acquire resistance to these agents. Acquired resistance arises by mutation or acquisition of exogenous resistance determinants and can be mediated by several mechanisms (degrading enzymes, reduced permeability, active efflux and target modification). Overall, resistance rates are on the increase, and may be different in different settings, so that surveillance of P. aeruginosa susceptibility is essential for the definition of empirical regimens. Multidrug resistance is frequent, and clinical isolates resistant to virtually all anti-pseudomonal agents are increasingly being reported. Monotherapy is usually recommended for uncomplicated urinary tract infections, while combination therapy is normally recommended for severe infections, such as bacteraemia and pneumonia, although, at least in some cases, the advantage of combination therapy remains a matter of debate. Antimicrobial use is a risk factor for P. aeruginosa resistance, especially with some agents (fluoroquinolones and carbapenems), and interventions based on antimicrobial rotation and restriction of certain agents can be useful to control the spread of resistance. Similar measures, together with the prudent use of antibiotics and compliance with infection control measures, are essential to preserve the efficacy of the currently available anti-pseudomonal agents, in view of the dearth, in the near future, of new options against multidrug-resistant P. aeruginosa strains.

Helicobacter pylori eradication has the potential to prevent gastric cancer: a state-of-the-art critique

Helicobacter pylori infection continues to play a key role in gastric diseases. Colonization of the gastric mucosa with the bacterium invariably results in the development of chronic gastritis and subsets of patients have a progression of the chronic gastritis to either ulcer or cancer. Epidemiological evidence indicates that the proportion of all gastric cancers attributable to H. pylori infection, and hence potentially preventable upon elimination of this risk factor, is somewhere in the range of 60% to 90%. This portends significant benefit in terms of morbidity and mortality, not least in populations with high prevalence of H. pylori infection coupled with high incidence of gastric cancer. The effect of prophylactic H. pylori eradication on gastric cancer incidence in humans remains unknown, however. Results from randomized trials are eagerly awaited, but availability of strong conclusive results may take many years. A growing number of studies show considerable variation in risk for gastric cancer development, depending on H. pylori strain type and the genetic predisposition of the host. There is also a remote possibility that elimination of the infection may have adverse health implications (e.g., antibiotic resistance), and therefore "simple" risk stratification and targeted chemoprevention is required. Based on "in depth" evidence presented at this workshop, the majority of the scientific task force favored a search-and-treat strategy in first-degree relatives of gastric cancer patients and an overwhelming majority felt that a more general screen-and-treat strategy should be focused in the first instance on a population with a high incidence of H. pylori-associated diseases.

Results of an antimicrobial control program at a university hospital

PURPOSE

The results of the first five years of an ongoing antimicrobial control program are reported.

METHODS

In 1998, a multidisciplinary antimicrobial subcommittee of the pharmacy and therapeutics committee of a university hospital was formed and charged with making formulary interventions in an effort to reduce rising antimicrobial resistance rates and drug expenditures. In 1999, a number of measures were implemented for controlling antimicrobial use. Selected antimicrobials with the potential for inappropriate use or whose inappropriate use had been documented were placed in the control of physicians in the infectious diseases (ID) division. Prior approval by an ID physician was required before the pharmacy could dispense these agents. Other key interventions included removal of ceftazidime and cefotaxime from the formulary, restriction of vancomycin and carbapenem use, and replacement of ciprofloxacin with levofloxacin as the sole fluoroquinolone on the formulary. Data regarding antimicrobial use and expenditures between 1998 and 2002 were compared and analyzed.

RESULTS

Antimicrobial use was reduced by 80% for third-generation cephalosporins and 15% for vancomycin following the implementation of the new antimicrobial policies. Antimicrobial-resistance patterns for many important gram-negative pathogens, including Pseudomonas aeruginosa, demonstrated a reversal of previous increases. In addition, the rate of methicillin-resistant Staphylococcus aureus decreased by an average of 3% each year from 1999 to 2002. Pharmacy expenditures for all antimicrobials, including antiviral, antifungal, and antibacterial agents, decreased 24.7%, with a cumulative cost saving of 1,401,126 US dollars, without inflation assumptions.

CONCLUSION

The implementation of an antimicrobial control program decreased the use of selected antimicrobial agents and resulted in substantial reduction of expenditures for antimicrobials.

Antibiotic susceptibility and REP-PCR fingerprints of Acinetobacter spp. isolated from a hospital ten years apart

The antibiotic susceptibility profiles and the repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR)-determined genotypes of 109 Acinetobacter strains collected from the University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia, in 1987 (N=21) and 1996-1998 (N=88) were established. Twelve antibiotic susceptibility profiles of antibiotics used at the UMMC were obtained. In descending order of effectiveness, imipenem, amikacin and ciprofloxacin were the most effective against the Acinetobacter strains. Compared with 1987 isolates, the isolates obtained in 1996-1998 had decreased susceptibility to these antibiotics and were tolerant to the antibiotics up to an MIC90 of > or =256 mg/L. REP-PCR DNA fingerprints of all the isolates revealed the presence of four Acinetobacter spp. lineages; 92% of all the isolates belonged to two dominant lineages (genotypes 1 and 4). Genotype 4 isolates predominant in 1987 showed increased resistance and antibiotic tolerance to imipenem, amikacin and ciprofloxacin compared with the 1996-1998 isolates. In contrast, genotype 1 isolates from 1996-1998 were mainly sensitive to these antibiotics. These findings demonstrate the presence of at least two independent Acinetobacter spp. lineages in the same hospital, and suggest the possibility that genotype 4 Acinetobacter spp. acquired the resistance phenotype in situ, whereas most of the genotype 1 isolates were probably introduced to the hospital in recent years.