Imipenem and ciprofloxacin consumption as factors associated with high incidence rates of resistant Pseudomonas aeruginosa in hospitals in northern France

An overview of the hospitals’ antimicrobial stewardship programs implemented to improve antibiotics’ utilization, cost and resistance patterns

Introduction: The high reliance of the physicians and surgeons on the antibiotics since their discovery has led to an irrational antibiotic utilization which not only has raised the incidence of antimicrobial resistance (AMR) but also increased the cost of treatment with antibiotics as high use of antibiotics has been found related to the occurrence of certain nosocomial infections which need extra antibiotic courses to be cured. In order to overcome these antibiotic utilization related problems an antimicrobial stewardship (AMS) program being the set of various persuasive, restrictive and structural interventions is considered an effective tool to rationalize the in-patient antimicrobial utilization worldwide. Method: The focus of this review is on the interventions that are being implemented during the in-patient AMS programs and have been described effective in controlling the antibiotic utilization, their cost of treatment and an overall infection control. The literature containing the information about various AMS interventions effecting the utilization and cost patterns along with the impact on AMR was searched in various databases such as PubMed, Google Scholar, Science Direct, Ovid (Medline) and Scopus. The categorical sorting of the published data is based on various AMS interventions such as the guideline development, formulary restriction (pre-authorization), educative interventions, clinical pathway development and prospective (post prescription) audit. Considering the objectives of the study such as the goal to curb overutilization of antibiotics, control of their cost of treatment for in-patients and infection control the sorted literature is presented in three different tables describing the AMS impact on the said outcomes. Results: The post AMS changes in utilization patterns are described as fall of antibiotics defined daily doses (DDD) and days of therapy (DOT) which resulted in the reduction of the cost of treatment with antibiotics. The reduction of the cost of treatment with antibiotics also resulted due to the AMS impact on the control of various nosocomial and multi-drug resistant (MDR) infections. Conclusion:  It has been concluded that the AMS program if implemented under the supervision of an expert AMS team mainly comprising of an infectious disease (ID) physician, clinical pharmacists and microbiologists with considerable support by the hospital authorities could be a highly efficient tool of the pharmacovigilance for rationalizing the in-patient antimicrobial practice.

Carbapenem-resistant Pseudomonas aeruginosa and carbapenem use in Japan: an ecological study

Objective

This study focused on carbapenem resistance in Pseudomonas aeruginosa and examined potential ecological correlations with carbapenem use in Japan.

Methods

The proportion of carbapenem-resistant P. aeruginosa isolates from 2015 and 2016 by prefecture was obtained from the Japan Nosocomial Infections Surveillance system. Data on carbapenem use was obtained from the National Database of Health Insurance Claims. The correlation between the proportion of carbapenem-resistant isolates and carbapenem consumption was assessed in a cross-sectional manner. The study also collected information on other variables including the numbers of physicians, nurses and medical facilities per 100 000 individuals by prefecture.

Results

Both the proportion of carbapenem-resistant P. aeruginosa isolates and levels of carbapenem use were higher in western Japan. Using a multivariate model, only carbapenem use remained significantly associated with the proportion of carbapenem-resistant isolates.

Conclusions

Carbapenem use and the proportion of carbapenem-resistant P. aeruginosa isolates were positively correlated. By longitudinal data collection, this approach offers an avenue to establish causal links as the frequency of carbapenem-resistant P. aeruginosa isolates starts to change in the future.

Prior antibiotic use and acquisition of multidrug-resistant organisms in hospitalized children: A systematic review

Objective:

Multidrug-resistant organisms (MDROs) cause ~5%–10% of infections in hospitalized children, leading to an increased risk of death, prolonged hospitalization, and additional costs. Antibiotic exposure is considered a driving factor of MDRO acquisition; however, consensus regarding the impact of antibiotic factors, especially in children, is lacking. We conducted a systematic review to examine the relationship between antibiotic use and subsequent healthcare-associated infection or colonization with an MDRO in children.

Design:

Systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline.

Methods:

We searched PubMed and Embase for all English, peer-reviewed original research studies published before September 2018. Included studies evaluated hospitalized children, antibiotic use as an exposure, and bacterial MDRO as an outcome.

Results:

Of the 535 studies initially identified, 29 met the inclusion criteria. Overall, a positive association was identified in most studies evaluating a specific antibiotic exposure (17 of 21, 81%), duration of antibiotics (9 of 12, 75%), and number of antibiotics received (2 of 3, 67%). Those studies that evaluated any antibiotic exposure had mixed results (5 of 10, 50%). Study sites, populations, and definitions of antibiotic use and MDROs varied widely.

Conclusions:

Published studies evaluating this relationship are limited and are of mixed quality. Limitations include observation bias in recall of antibiotic exposure, variations in case definitions, and lack of evaluation of antibiotic dosing and appropriateness. Additional studies exploring the impact of antibiotic use and MDRO acquisition may be needed to develop effective antibiotic stewardship programs for hospitalized children.

Antibiofilm potential of purified environmental bacteriophage preparations against early stage Pseudomonas aeruginosa biofilms

AIMS

This paper presents the potential of environmentally sourced bacteriophages to affect the growth of clinical isolates of Pseudomonas aeruginosa biofilms, and assesses the respective plaque morphotypes presented by each bacteriophage, in vitro.

METHODS AND RESULTS

Bacterial host strains were typed for their ability to produce the quorum sensing-controlled virulence factor pyocyanin, and then tested for bacteriophage susceptibility using the spot test method. The bacteriophages were co-administered with ciprofloxacin in order to determine whether the bacteriophages would demonstrate synergistic or antagonistic behaviour to the antibiotic in vitro. Results suggest a potential relationship between the bacteriophage plaque size and biofilm inhibition, where those producing smaller plaques appear to be more effective at reducing bacterial biofilm formation.

CONCLUSIONS

This phenomenon may be explained by a high adsorption rate leading to the rapid formation of smaller plaques, and greater biofilm reduction associated with the loss of viable bacterial cells before the cells can adhere to the surface and form a biofilm. Results from the co-administration of bacteriophage and ciprofloxacin suggest that the two work synergistically to affect P. aeruginosa biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data indicate enhanced efficacy of ciprofloxacin by ≥50%. This could offer an alternative strategy for targeting antibiotic-resistant infections.

Variation in antibiotic use among and within different settings: a systematic review

Objectives

Variation in antibiotic use may reflect inappropriate use. We aimed to systematically describe the variation in measures for antibiotic use among settings or providers. This study was conducted as part of the innovative medicines initiative (IMI)-funded international project DRIVE-AB.

Methods

We searched for studies published in MEDLINE from January 2004 to January 2015 reporting variation in measures for systemic antibiotic use (e.g. DDDs) in inpatient and outpatient settings. The ratio between a study's reported maximum and minimum values of a given measure [maximum:minimum ratio (MMR)] was calculated as a measure of variation. Similar measures were grouped into categories and when possible the overall median ratio and IQR were calculated.

Results

One hundred and forty-three studies were included, of which 85 (59.4%) were conducted in Europe and 12 (8.4%) in low- to middle-income countries. Most studies described the variation in the quantity of antibiotic use in the inpatient setting (81/143, 56.6%), especially among hospitals (41/81, 50.6%). The most frequent measure was DDDs with different denominators, reported in 23/81 (28.4%) inpatient studies and in 28/62 (45.2%) outpatient studies. For this measure, we found a median MMR of 3.7 (IQR 2.6-5.0) in 4 studies reporting antibiotic use in ICUs in DDDs/1000 patient-days and a median MMR of 2.3 (IQR 1.5-3.2) in 18 studies reporting outpatient antibiotic use in DDDs/1000 inhabitant-days. Substantial variation was also identified in other measures.

Conclusions

Our review confirms the large variation in antibiotic use even across similar settings and providers. Data from low- and middle-income countries are under-represented. Further studies should try to better elucidate reasons for the observed variation to facilitate interventions that reduce unwarranted practice variation. In addition, the heterogeneity of reported measures clearly shows that there is need for standardization.

Infection-related ventilator-associated complications in ICU patients colonised with extended-spectrum β-lactamase-producing Enterobacteriaceae

PURPOSE

To investigate the clinical significance of infection-related ventilator-associated complications (IVAC) and their impact on carbapenem consumption in mechanically ventilated (MV) patients colonised with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBLE).

METHODS

Inception cohort study from the French prospective multicenter OUTCOMEREA database (17 ICUs, 1997-2015) including all ESBLE carriers (systematic rectal swabbing at admission then weekly and/or urinary or superficial surgical site colonisation) with MV duration > 48 h and ≥ 1 episode of IVAC after carriage documentation. All ICU-acquired infections were microbiologically documented.

RESULTS

The 318 enrolled ESBLE carriers (median age 68 years; males 67%; medical admission 68%; imported carriage 53%) experienced a total of 576 IVAC comprising 361 episodes (63%) without documented infection, 124 (21%) related to infections other than ventilator-associated pneumonia (VAP), 73 (13%) related to non-ESBLE VAP and 18 (3%) related to ESBLE VAP. Overall, ESBLE infections accounted for only 43 episodes (7%). Carbapenem exposure within the preceding 3 days was the sole independent predictor of ESBLE infection as the causative event of IVAC, with a protective effect (adjusted odds ratio 0.2, 95% confidence interval 0.05-0.6; P < 0.01). Carbapenems were initiated in 9% of IVAC without infection, 15% of IVAC related to non-VAP infections, 42% of IVAC related to non-ESBLE VAP, and 56% of IVAC related to ESBLE VAP (ESBLE VAP versus non-ESBLE VAP: P = 0.43).

CONCLUSIONS

IVAC in ESBLE carriers mostly reflect noninfectious events but act as a strong driver of empirical carbapenem consumption. ESBLE infections are scarce yet hard to predict, strengthening the need for novel diagnostic approaches and carbapenem-sparing alternatives.

Long-term efficacy of comprehensive multidisciplinary antibiotic stewardship programs centered on weekly prospective audit and feedback

OBJECTIVE

To evaluate the long-term effects of comprehensive antibiotic stewardship programs (ASPs) on antibiotic use, antimicrobial-resistant bacteria, and clinical outcomes.

DESIGN

Before-after study.

SETTING

National university hospital with 934 beds.

INTERVENTION

Implementation in March 2010 of a comprehensive ASPs including, among other strategies, weekly prospective audit and feedback with multidisciplinary collaboration.

METHODS

The primary outcome was the use of antipseudomonal antibiotics as measured by the monthly mean days of therapy per 1000 patient days each year. Secondary outcomes included overall antibiotic use and that of each antibiotic class, susceptibility of Pseudomonas aeruginosa, the proportion of patients isolated methicillin-resistant Staphylococcus aureus (MRSA) among all patients isolated S. aureus, the incidence of MRSA, and the 30-day mortality attributable to bacteremia.

RESULTS

The mean monthly use of antipseudomonal antibiotics significantly decreased in 2011 and after as compared with 2009. Susceptibility to levofloxacin was significantly increased from 2009 to 2016 (P = 0.01 for trend). Its susceptibility to other antibiotics remained over 84% and did not change significantly during the study period. The proportion of patients isolated MRSA and the incidence of MRSA decreased significantly from 2009 to 2016 (P < 0.001 and = 0.02 for trend, respectively). There were no significant changes in the 30-day mortality attributable to bacteremia during the study period (P = 0.57 for trend).

CONCLUSION

The comprehensive ASPs had long-term efficacy for reducing the use of the targeted broad-spectrum antibiotics, maintaining the antibiotic susceptibility of P. aeruginosa, and decreasing the prevalence of MRSA, without adversely affecting clinical outcome.

Evaluating the Relationship Between Hospital Antibiotic Use and Antibiotic Resistance in Common Nosocomial Pathogens

OBJECTIVE The relationship between hospital antibiotic use and antibiotic resistance is poorly understood. We evaluated the association between antibiotic utilization and resistance in academic and community hospitals in Ontario, Canada. METHODS We conducted a multicenter observational ecological study of 37 hospitals in 2014. Hospital antibiotic purchasing data were used as an indicator of antibiotic use, whereas antibiotic resistance data were extracted from hospital indexes of resistance. Multivariate regression was performed, with antibiotic susceptibility as the primary outcome, antibiotic consumption as the main predictor, and additional covariates of interest (ie, hospital type, laboratory standards, and patient days). RESULTS With resistance data representing more than 90,000 isolates, we found the increased antibiotic consumption in defined daily doses per 1,000 patient days (DDDs/1,000 PD) was associated with decreased antibiotic susceptibility for Pseudomonas aeruginosa (-0.162% per DDD/1,000 PD; P=.119). However, increased antibiotic consumption predicted increased antibiotic susceptibility significantly for Escherichia coli (0.173% per DDD/1,000 PD; P=.005), Klebsiella spp (0.124% per DDD/1,000 PD; P=.004), Enterobacter spp (0.194% per DDD/1,000 PD; P=.003), and Enterococcus spp (0.309% per DDD/1,000 PD; P=.001), and nonsignificantly for Staphylococcus aureus (0.012% per DDD/1,000 PD; P=.878). Hospital type (P=.797) and laboratory standard (P=.394) did not significantly predict antibiotic susceptibility, while increased hospital patient days generally predicted increased organism susceptibility (0.728% per 10,000 PD; P<.001). CONCLUSIONS We found that hospital-specific antibiotic usage was generally associated with increased, rather than decreased hospital antibiotic susceptibility. These findings may be explained by community origins for many hospital-diagnosed infections and practitioners choosing agents based on local antibiotic resistance patterns. Infect Control Hosp Epidemiol 2017;38:1457-1463.

Formulation of carbapenems loaded gold nanoparticles to combat multi-antibiotic bacterial resistance: In vitro antibacterial study

Despite the fact that carbapenems (powerful β-lactams antibiotics) were able to fight serious infectious diseases, nowadays the spread of carbapenems-resistant bacteria is considered the main challenge in antibacterial therapy. In this study, we focused on evaluating the surface conjugation of carbapenems (imipenem and meropenem) with gold nanoparticles as a delivering strategy to specifically and safely maximize their therapeutic efficacy while destroying the developing resistance of the pathogens. Different particle size formulae (35, 70 and 200nm) were prepared by citrate reduction method. The prepared nanoparticles were functionalized with imipenem (Ipm) or meropenem (Mem) and physico-chemically characterized for loading efficiency, particle size, morphology, and in-vitro release. The antibacterial efficacy was also evaluated against carbapenems resistant Gram-negative bacteria isolated from infected human, through measuring the minimum inhibitory concentration and antibiotic kill test. All the obtained gold nanoparticles showed a distinct nano-size with loading efficiency up to 72% and 74% for Ipm and Mem, respectively. The conjugation and physico-chemical stability of the formulated carbapenems were confirmed by FTIR and X-RPD. Diffusion driven release behavior was observed for both Ipm and Mem from all of the loaded gold nanoparticles. For both Ipm and Mem, formula with 35nm diameter showed the most significant enhancement in antibacterial activity against all the selected isolates including Klebsiella pneumoniae, Proteus mirabilis and Acinteobacter baumanii. Ipm loaded Gold nanoparticles demonstrated decrease in the MIC of Ipm down to four folds, whereas, Mem loaded gold nanoparticles showed decrease in the MIC of Mem down to three folds on the tested bacterial isolates. Based on these results, the formulation of carbapenems-loaded gold nanoparticles demonstrated to be a promising nano-size delivery vehicle for improving the therapeutic activity and destroying the bacterial resistance for carbapenems.

Integron occurrence is linked to reduced biocide susceptibility in multidrug resistant Pseudomonas aeruginosa

OBJECTIVE

Integrons are gene acquisition systems commonly found in bacterial genomes that play a major role in the dissemination of resistance to antibiotics. This work aimed to study the relationship between the presence of integrons and the reduced susceptibility of multidrug-resistant (MDR) Pseudomonas aeruginosa isolates towards different groups of biocides.

METHODS

The antimicrobial susceptibility patterns of 104 clinical isolates were determined against different antibiotics by the disk diffusion method. The isolates were also tested for their susceptibility to six biocides (glutaraldehyde, benzalkonium chloride, cetrimide, chlorhexidine gluconate, chlorocresol and gluconate, and phenyl mercuric nitrate) by agar dilution. The presence of integrons and resistance genes in MDR isolates were detected by polymerase chain reaction.

RESULTS

Thirty-six Pseudomonas isolates were MDR, and the majority of these isolates showed reduced susceptibility to biocides. In the MDR isolates, Class I integron was detected in 22 isolates (61.1%), while Class II and III integrons were identified in only four isolates (11.1%), In addition, aacA4 and qacE genes were detected in 22 (61.1%) and 11 (30.5%) isolates, respectively. Integron I-positive isolates showed reduced susceptibility to tested biocides.

CONCLUSIONS

The current study reveals the presence of different classes of integrons, with class I being predominant. Class I integron may be responsible for generating MDR P. aeruginosa isolates with reduced susceptibility to biocides. This linkage between integrons and biocide resistance in MDR-Pseudomonas isolates is notable and could be clinically important. Strict antibiotic prescription policies and the adequate use of biocides could help in controlling this problem.

Strategies to enhance rational use of antibiotics in hospital: a guideline by the German Society for Infectious Diseases

Introduction

In the time of increasing resistance and paucity of new drug development there is a growing need for strategies to enhance rational use of antibiotics in German and Austrian hospitals. An evidence-based guideline on recommendations for implementation of antibiotic stewardship (ABS) programmes was developed by the German Society for Infectious Diseases in association with the following societies, associations and institutions: German Society of Hospital Pharmacists, German Society for Hygiene and Microbiology, Paul Ehrlich Society for Chemotherapy, The Austrian Association of Hospital Pharmacists, Austrian Society for Infectious Diseases and Tropical Medicine, Austrian Society for Antimicrobial Chemotherapy, Robert Koch Institute.

Materials and methods

A structured literature research was performed in the databases EMBASE, BIOSIS, MEDLINE and The Cochrane Library from January 2006 to November 2010 with an update to April 2012 (MEDLINE and The Cochrane Library). The grading of recommendations in relation to their evidence is according to the AWMF Guidance Manual and Rules for Guideline Development.

Conclusion

The guideline provides the grounds for rational use of antibiotics in hospital to counteract antimicrobial resistance and to improve the quality of care of patients with infections by maximising clinical outcomes while minimising toxicity. Requirements for a successful implementation of ABS programmes as well as core and supplemental ABS strategies are outlined. The German version of the guideline was published by the German Association of the Scientific Medical Societies (AWMF) in December 2013.

Ten key points for the appropriate use of antibiotics in hospitalised patients: a consensus from the Antimicrobial Stewardship and Resistance Working Groups of the International Society of Chemotherapy

The Antibiotic Stewardship and Resistance Working Groups of the International Society for Chemotherapy propose ten key points for the appropriate use of antibiotics in hospital settings. (i) Get appropriate microbiological samples before antibiotic administration and carefully interpret the results: in the absence of clinical signs of infection, colonisation rarely requires antimicrobial treatment. (ii) Avoid the use of antibiotics to 'treat' fever: use them to treat infections, and investigate the root cause of fever prior to starting treatment. (iii) Start empirical antibiotic treatment after taking cultures, tailoring it to the site of infection, risk factors for multidrug-resistant bacteria, and the local microbiology and susceptibility patterns. (iv) Prescribe drugs at their optimal dosing and for an appropriate duration, adapted to each clinical situation and patient characteristics. (v) Use antibiotic combinations only where the current evidence suggests some benefit. (vi) When possible, avoid antibiotics with a higher likelihood of promoting drug resistance or hospital-acquired infections, or use them only as a last resort. (vii) Drain the infected foci quickly and remove all potentially or proven infected devices: control the infection source. (viii) Always try to de-escalate/streamline antibiotic treatment according to the clinical situation and the microbiological results. (ix) Stop unnecessarily prescribed antibiotics once the absence of infection is likely. And (x) Do not work alone: set up local teams with an infectious diseases specialist, clinical microbiologist, hospital pharmacist, infection control practitioner or hospital epidemiologist, and comply with hospital antibiotic policies and guidelines.

A realist analysis of hospital patient safety in Wales: applied learning for alternative contexts from a multisite case study

Background

Hospital patient safety is a major social problem. In the UK, policy responses focus on the introduction of improvement programmes that seek to implement evidence-based clinical practices using the Model for Improvement, Plan-Do-Study-Act cycle. Empirical evidence that the outcomes of such programmes vary across hospitals demonstrates that the context of their implementation matters. However, the relationships between features of context and the implementation of safety programmes are both undertheorised and poorly understood in empirical terms.

Objectives

This study is designed to address gaps in conceptual, methodological and empirical knowledge about the influence of context on the local implementation of patient safety programmes.

Design

We used concepts from critical realism and institutional analysis to conduct a qualitative comparative-intensive case study involving 21 hospitals across all seven Welsh health boards. We focused on the local implementation of three focal interventions from the 1000 Lives+patient safety programme: Improving Leadership for Quality Improvement, Reducing Surgical Complications and Reducing Health-care Associated Infection. Our main sources of data were 160 semistructured interviews, observation and 1700 health policy and organisational documents. These data were analysed using the realist approaches of abstraction, abduction and retroduction.

Setting

Welsh Government and NHS Wales.

Participants

Interviews were conducted with 160 participants including government policy leads, health managers and professionals, partner agencies with strategic oversight of patient safety, advocacy groups and academics with expertise in patient safety.

Main outcome measures

Identification of the contextual factors pertinent to the local implementation of the 1000 Lives+patient safety programme in Welsh NHS hospitals.

Results

An innovative conceptual framework harnessing realist social theory and institutional theory was produced to address challenges identified within previous applications of realist inquiry in patient safety research. This involved the development and use of an explanatory intervention–context–mechanism–agency–outcome (I-CMAO) configuration to illustrate the processes behind implementation of a change programme. Our findings, illustrated by multiple nested I-CMAO configurations, show how local implementation of patient safety interventions are impacted and modified by particular aspects of context: specifically, isomorphism, by which an intervention becomes adapted to the environment in which it is implemented; institutional logics, the beliefs and values underpinning the intervention and its source, and their perceived legitimacy among different groups of health-care professionals; and the relational structure and power dynamics of the functional group, that is, those tasked with implementing the initiative. This dynamic interplay shapes and guides actions leading to the normalisation or the rejection of the patient safety programme.

Conclusions

Heightened awareness of the influence of context on the local implementation of patient safety programmes is required to inform the design of such interventions and to ensure their effective implementation and operationalisation in the day-to-day practice of health-care teams. Future work is required to elaborate our conceptual model and findings in similar settings where different interventions are introduced, and in different settings where similar innovations are implemented.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Pseudomonas aeruginosa Infection after Pancreatoduodenectomy: Risk Factors and Clinic Impacts

BACKGROUND

Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of nosocomial infections, which is difficult to treat because of limited susceptibility to antimicrobial agents. In China, isolation rates of P. aeruginosa were observed to increase by year. The incidence of infectious complications after pancreatoduodenectomy (PD) were high. However, there was no data available regarding P. aeruginosa infection in patients undergoing PD. This study evaluated the risk factors and clinical impacts of P. aeruginosa infection on patient after PD.

METHODS

119 patients who underwent PD with post-operative infectious complications were monitored for P. aeruginosa infection. The patients were grouped as P. aeruginosa infection and non-P. aeruginosa infection. Univariable and multivariable analyses were used to identify risk factors for P. aeruginosa infection.

RESULTS

42 (35.3%) of the119 patients were P. aeruginosa positive after PD. The sites of P. aeruginosa infection included (1) abdominal drain fluid (76%); (2) sputum (7%); (3) central line catheter tip cultures (2%); and (4) combination of sites (14%). Pseudomonas aeruginosa isolates were susceptible to Polymyxin B, Amikacin and Gentamicin, resistant to Aztreonam Piperacillin-tazobactam, Imipenem and Ceftazidime. History of diabetes mellitus (OR=2.981, P=0.023), pancreatic fistula (OR=4.699, P=0.001), use of carbapenems (OR=3.236, P=0.013), and fluoroquinolones (OR=2.940, P=0.044), antibiotics, and length of ICU stay (OR=2.133, P=0.022) independently predicted post-operative P. aeruginosa infection. Pseudomonas aeruginosa infection was related to severe post-operative complications, including delayed gastric emptying and post-pancreatectomy hemorrhage, but was not related to not 30-d mortality or a longer post-operative stay.

CONCLUSIONS

This analytic study highlights the prevalence and high drug resistance of P. aeruginosa after PD. Pseudomonas aeruginosa infection was related to severe post-operative complications but not 30-d mortality. Measures to combat P. aeruginosa infection would likely decrease the accidence of P. aeruginosa infection and benefit patients' outcomes.

Cyclic-di-GMP levels affect Pseudomonas aeruginosa fitness in the presence of imipenem

A large number of genes coding for enzymes predicted to synthesize and degrade 3'-5'-cyclic diguanylic acid (c-di-GMP) is found in most bacterial genomes and this dinucleotide emerged as an intracellular signal-controlling bacterial behaviour. An association between high levels of c-di-GMP and antibiotic resistance may be expected because c-di-GMP regulates biofilm formation and this mode of growth leads to enhanced antibiotic resistance. However, a clear understanding of this correlation has not been established. We found that increased levels of c-di-GMP in Pseudomonas aeruginosa improve fitness in the presence of imipenem, even when grown as planktonic cells. P. aeruginosa post-transcriptionally regulates the amounts of five porins in response to c-di-GMP, including OprD, responsible for imipenem uptake. Cells with low c-di-GMP levels are consequently more sensitive to this antibiotic. Main efflux pumps or β-lactamase genes did not show altered mRNA levels in P. aeruginosa strains with modified different c-di-GMP concentrations. Together, our findings show that c-di-GMP levels modulate fitness of planktonic cultures in the presence of imipenem.

Nosocomial urinary tract infections caused by Pseudomonas aeruginosa and Acinetobacter species: sensitivity to antibiotics and risk factors

BACKGROUND

Pseudomonas aeruginosa and Acinetobacter species frequently cause intrahospital urinary tract infections (IUTI), contributing to increased hospital morbidity and mortality. Our objective was further exploration of possible risk factors for development of IUTI caused by P aeruginosa and Acinetobacter spp, including their resistance to various antibiotics.

METHODS

The prospective case control study was conducted in Clinical Center Kragujevac, Serbia, during the period January 2009 to December 2011 and covered all patients with IUTI according to the Centers for Disease Control and Prevention criteria. The patients classified as "cases" had an IUTI caused by P aeruginosa or Acinetobacter spp. The control patients were matched to the cases and selected randomly from the remaining patients.

RESULTS

There were 79 cases (11.9%) and 586 (88.1%) controls in the study. According to the multivariate binary logistic regression, there were 3 significant predictors of P aeruginosa and Acinetobacter spp IUTI: male sex (odds ratio [OR], 0.423; 95% confidence interval [CI]: 0.251-0.711; P = .001), stay in another hospital ward before emergence of IUTI (OR, 1.704; 95% CI: 1.013-2.864; P = .044), and previous use of penicillins and their combinations with inhibitors of β-lactamases (OR, 2.643; 95% CI: 1.044-6.692; P = .040).

CONCLUSION

Knowing that IUTI caused by above-mentioned bacteria are especially frequent among male patients, after previous use of penicillins, and in patients who spent some time previously at other wards, sound strategies for prevention of such infections in clinical practice should be developed.

Aetiology and antibiotic resistance patterns of urinary tract infections in the elderly: a 6-month study

Urinary tract infections (UTIs) are a common cause of bacteraemia in the elderly and are associated with a high probability of hospitalization. Despite the impact of UTIs on health status and quality of life, a limited number of studies have evaluated their aetiology in this population. This study aimed to evaluate the microbial aetiology and pattern of susceptibility of bacteria causing UTIs in the elderly. For this purpose, a retrospective cohort study of elderly residents (n = 472, aged >65 years) in 14 nursing homes in Milan (Italy) and its province was performed. Globally, 393 micro-organisms from 328 samples were isolated: Escherichia coli was the most prevalent (44.8 %), followed by Proteus mirabilis (20.4 %), Providencia spp. (8.9 %), Klebsiella spp. (6.4 %) and Pseudomonas aeruginosa (4.6 %). Enterococci were the most frequently isolated Gram-positive organisms (7.4 %). Almost all Enterobacteriaceae were susceptible to nitrofurantoin, carbapenems and amikacin. Extended-spectrum β-lactamases were detected in 42.1 % of isolates. The most active antibiotics against P. aeruginosa were colistin, amikacin and piperacillin/tazobactam. All Gram-positive organisms were susceptible to glycopeptides and linezolid, and 90 % were susceptible to nitrofurantoin. Fluoroquinolones showed a limited activity against all the tested micro-organisms. Escherichia coli remains the major micro-organism responsible for UTIs in older people, although to a lesser extent than in a younger population. The high rates of resistance observed in this study make careful use of antibiotics advisable to limit further development of resistance.

How to reduce antibiotic consumption for community-acquired pneumonia?

BACKGROUND

The difficulty to diagnose community-acquired pneumonia (CAP) and the lack of scientific data regarding the optimal duration of antibiotic therapy are responsible for overprescribing antibiotics.

OBJECTIVE

The authors had for objective to perform a systematic review of the international medical literature on strategies aimed at reducing antibiotic consumption for CAP.

METHODS

We performed a Pubmed search using the keywords CAP, antibiotic use, duration of antibiotic therapy, procalcitonin, short-course treatment, and biomarkers. We then made a critical review of the selected articles.

RESULTS

Our review identified two strategies used to reduce antibiotic consumption for CAP. The first one was based on procalcitonin (PCT) use. This strategy, even though reducing the duration of antibiotic therapy, does not seem optimal since it is associated with longer antibiotic treatment than recommended by the Infectious Diseases Society of America. Moreover, this strategy is associated with an increased cost in biochemical tests. The other strategy is based on a 2-step clinical reassessment: 1) during the first 24 hours of hospitalization, to confirm the diagnosis of CAP and 2) during hospitalization, to shorten the duration of antibiotic therapy according to the patient's clinical status.

CONCLUSION

Clinical reassessment, currently little studied compared to PCT guidance algorithm, seems to be promising to reduce antibiotic consumption for CAP. Especially since it was never compared to PCT guidance strategy in a randomized clinical trial.

Emergence of imipenem-resistant gram-negative bacilli in intestinal flora of intensive care patients

Intestinal flora contains a reservoir of Gram-negative bacilli (GNB) resistant to cephalosporins, which are potentially pathogenic for intensive care unit (ICU) patients; this has led to increasing use of carbapenems. The emergence of carbapenem resistance is a major concern for ICUs. Therefore, in this study, we aimed to assess the intestinal carriage of imipenem-resistant GNB (IR-GNB) in intensive care patients. For 6 months, 523 consecutive ICU patients were screened for rectal IR-GNB colonization upon admission and weekly thereafter. The phenotypes and genotypes of all isolates were determined, and a case control study was performed to identify risk factors for colonization. The IR-GNB colonization rate increased regularly from 5.6% after 1 week to 58.6% after 6 weeks in the ICU. In all, 56 IR-GNB strains were collected from 50 patients: 36 Pseudomonas aeruginosa strains, 12 Stenotrophomonas maltophilia strains, 6 Enterobacteriaceae strains, and 2 Acinetobacter baumannii strains. In P. aeruginosa, imipenem resistance was due to chromosomally encoded resistance (32 strains) or carbapenemase production (4 strains). In the Enterobacteriaceae strains, resistance was due to AmpC cephalosporinase and/or extended-spectrum β-lactamase production with porin loss. Genomic comparison showed that the strains were highly diverse, with 8 exceptions (4 VIM-2 carbapenemase-producing P. aeruginosa strains, 2 Klebsiella pneumoniae strains, and 2 S. maltophilia strains). The main risk factor for IR-GNB colonization was prior imipenem exposure. The odds ratio for colonization was already as high as 5.9 (95% confidence interval [95% CI], 1.5 to 25.7) after 1 to 3 days of exposure and increased to 7.8 (95% CI, 2.4 to 29.8) thereafter. In conclusion, even brief exposure to imipenem is a major risk factor for IR-GNB carriage.

Prevalence of efflux-mediated ciprofloxacin and levofloxacin resistance in recent clinical isolates of Pseudomonas aeruginosa and its reversal by the efflux pump inhibitors 1-(1-naphthylmethyl)-piperazine and phenylalanine-arginine-β-naphthylamide

To assess the prevalence of efflux-driven fluoroquinolone (FQ) resistance in recent clinical isolates of Pseudomonas aeruginosa, a worrisome and often hospital-acquired pathogen, 115 unique strains were collected over a 5-month period, of which 27 and 33 had decreased susceptibility to ciprofloxacin (CIP) and levofloxacin (LVX), respectively. The MIC(50) (minimum inhibitory concentration for 50% of the organisms) was 16 μg/mL for both FQs. The efflux pump inhibitors (EPIs) phenylalanine-arginine-β-naphthylamide (PAβN) and 1-(1-naphthylmethyl)-piperazine (NMP) were then used to evaluate their efficacy in reducing CIP and LVX MICs. NMP did not significantly modify CIP MICs, whilst PAβN resulted in MIC(50) values of 2 μg/mL and 0.125 μg/mL for CIP and LVX, respectively. With the addition of PAβN, susceptibility to CIP and LVX was recovered in 6 (22.2%) and 31 (93.9%) strains, respectively. The best combination to reverse FQ resistance in this set of strains was LVX with PAβN. The results of this study show that the effect of an EPI is not only dependent on the species on which it is used but also on the molecule associated with it. Therefore, the design of an EPI equally efficient on all resistance-nodulation-cell division (RND) efflux pumps appears to be difficult and, from a practical point of view, if an EPI is developed for clinical use, the efficiency of its combination with a definite molecule should be assessed carefully against a wide range of clinical isolates to evaluate the real benefit of this combination.