[Update on antimicrobial chemotherapy]

Linezolid susceptibility in Helicobacter pylori, including strains with multidrug resistance

Only a few studies have evaluated Helicobacter pylori susceptibility to linezolid. The aim of the present study was to assess linezolid susceptibility in H. pylori, including strains with double/multidrug resistance. The susceptibility of 53 H. pylori strains was evaluated by Etest and a breakpoint susceptibility testing method. Helicobacter pylori resistance rates were as follows: amoxicillin, 1.9%; metronidazole, 37.7%; clarithromycin, 17.0%; tetracycline, 1.9%; levofloxacin, 24.5%; and linezolid (>4 mg/L), 39.6%. The linezolid MIC50 value was 31.2-fold higher than that of clarithromycin and 10.5-fold higher than that of levofloxacin; however, 4 of 11 strains with double/multidrug resistance were linezolid-susceptible. The MIC range of the oxazolidinone agent was larger (0.125-64 mg/L) compared with those in the previous two reports. The linezolid resistance rate was 2.2-fold higher in metronidazole-resistant strains and in strains resistant to at least one antibiotic compared with the remaining strains. Briefly, linezolid was less active against H. pylori compared with clarithromycin and levofloxacin, and linezolid resistance was linked to resistance to metronidazole as well as to resistance to at least one antibiotic. However, linezolid activity against some strains with double/multidrug resistance may render the agent appropriate to treat some associated H. pylori infections following in vitro susceptibility testing of the strains. Clinical trials are required to confirm this suggestion.

Antimicrobial stewardship and linezolid

BACKGROUND

Since 2002, linezolid, the first representative of the oxazolidinone class, has been widely prescribed, sometimes outside of approved indications. However, several cases of clinical outbreaks due to linezolid-resistant organisms have been reported, and its relatively high cost represents an economic challenge for hospital settings.

OBJECTIVES

The aim of this study was to assess the impact of different actions conducted by an antimicrobial stewardship team (AST) to control over-prescription of linezolid with regard to the defined daily dose (DDD) per 1,000 inhabitants per day.

SETTING

This work was conducted in a 1,495-bed hospital from 2009 to 2013. An AST, gathering the departments of pharmacy, microbiology, and infectious diseases, assessed the pertinence of linezolid use and associated effect on the prescriber.

METHOD

A retrospective study was conducted throughout 2009. Three different evaluations were prospectively carried out, each for 3 months, between 2011 and 2013.

MAIN OUTCOME MEASURE

The indicators chosen to monitor the consumption of linezolid were the DDD per 1,000 inhabitants per day, which enabled a comparison to be made between hospitals from 2004 to 2012, and of the pertinence of its prescription by different departments.

RESULTS

From 2009 to 2013, 239 patients were evaluated through three 3-month stages. Prescriptions were for off-label use in 45 % of cases. Prescriptions were considered appropriate in 60 % of cases. Unsuitable treatment was either modified or discontinued (62 and 38 % of cases, respectively). Mean duration of linezolid treatment was 8 days, i.e. below the national mean duration reported in the literature. To highlight the impact of action taken by the team, a consensual strategy to treat ventilator-acquired pneumonia was elaborated with principal prescribers. Throughout the study, the mean DDD per 1,000 inhabitants per day increased very slowly and was lower than the eleven other French hospitals, which were secondarily included in this study.

CONCLUSION

The multidisciplinary approach that was adopted for therapeutic education and delivery control led to an improvement in the proper use of linezolid. Similar strategy should be extended to other antimicrobial agents, such as carbapenems, for which both cost and risk of resistance emergence are of major concern.

De-escalation of antimicrobial treatment for adults with sepsis, severe sepsis or septic shock

BACKGROUND

Mortality rates among patients with sepsis, severe sepsis or septic shock are highly variable throughout different regions or services and can be upwards of 50%. Empirical broad-spectrum antimicrobial treatment is aimed at achieving adequate antimicrobial therapy, thus reducing mortality; however, there is a risk that empirical broad-spectrum antimicrobial treatment can expose patients to overuse of antimicrobials. De-escalation has been proposed as a strategy to replace empirical broad-spectrum antimicrobial treatment by using a narrower antimicrobial therapy. This is done by reviewing the patient's microbial culture results and then making changes to the pharmacological agent or discontinuing a pharmacological combination.

OBJECTIVES

To evaluate the effectiveness and safety of de-escalation antimicrobial treatment for adult patients diagnosed with sepsis, severe sepsis or septic shock caused by any micro-organism.

SEARCH METHODS

In this updated version, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 10); MEDLINE via PubMed (from inception to October 2012); EMBASE (from inception to October 2012); LILACS (from inception to October 2012); Current Controlled Trials; bibliographic references of relevant studies; and specialists in the area. We applied no language restriction. We had previously searched the databases to August 2010.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) comparing de-escalation (based on culture results) versus standard therapy for adults with sepsis, severe sepsis or septic shock. The primary outcome was mortality (at 28 days, hospital discharge or at the end of the follow-up period). Studies including patients initially treated with an empirical but not adequate antimicrobial therapy were not considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors planned to independently select and extract data and to evaluate methodological quality of all studies. We planned to use relative risk (risk ratio) for dichotomous data and mean difference (MD) for continuous data, with 95% confidence intervals. We planned to use the random-effects statistical model when the estimate effects of two or more studies could be combined in a meta-analysis.

MAIN RESULTS

Our search strategy retrieved 493 studies. No published RCTs testing de-escalation of antimicrobial treatment for adult patients diagnosed with sepsis, severe sepsis or septic were included in this review. We found one ongoing RCT.

AUTHORS' CONCLUSIONS

There is no adequate, direct evidence as to whether de-escalation of antimicrobial agents is effective and safe for adults with sepsis, severe sepsis or septic shock. This uncertainty warrants further research via RCTs and the authors are awaiting the results of an ongoing RCT testing the de-escalation of empirical antimicrobial therapy for severe sepsis.

Phytochemical Analysis and Antimicrobial, Antinociceptive, and Anti-Inflammatory Activities of Two Chemotypes of Pimenta pseudocaryophyllus (Myrtaceae)

Preparations from Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae) have been widely used in Brazilian folk medicine. This study aims to evaluate the antimicrobial activity of the crude ethanol extracts, fractions, semipurified substances, and essential oils obtained from leaves of two chemotypes of P. pseudocaryophyllus and to perform the antinociceptive and anti-inflammatory screening. The ethanol extracts were purified by column chromatography and main compounds were spectrally characterised (1D and 2D ¹H and ¹³C NMR). The essential oils constituents were identified by GC/MS. The broth microdilution method was used for testing the antimicrobial activity. The abdominal contortions induced by acetic acid and the ear oedema induced by croton oil were used for screening of antinociceptive and anti-inflammatory activities, respectively. The phytochemical analysis resulted in the isolation of pentacyclic triterpenes, flavonoids, and phenol acids. The oleanolic acid showed the best profile of antibacterial activity for Gram-positive bacteria (31.2–125 μg mL⁻¹), followed by the essential oil of the citral chemotype (62.5–250 μg mL⁻¹). Among the semipurified substances, Ppm5, which contained gallic acid, was the most active for Candida spp. (31.2 μg mL⁻¹) and Cryptococcus spp. (3.9–15.6 μg mL⁻¹). The crude ethanol extract and fractions from citral chemotype showed antinociceptive and anti-inflammatory effects.

In Vitro Activities of Ertapenem and Imipenem against Clinical Extended Spectrum Beta-Lactamase-Producing Enterobacteriaceae Collected in Military Teaching Hospital Mohammed V of Rabat

Objective. To study the sensitivity level of extended spectrum beta-lactamase-producing Enterobacteriaceae to Carbapenems (Imipenem, Ertapenem) marketed in Morocco and discusses the place of Ertapenem in the treatment of extended spectrum-beta-lactamase-producing. Materials and Methods. A retrospective study of 110 extended spectrum beta-lactamase-producing Enterobacteriaceae. Isolates obtained from blood cultures, superficial and deep pus, and catheters were conducted. The minimum inhibitory concentrations of Imipenem and Ertapenem were done by the E-test. The modified Hodge test was conducted for resistant or intermediate strains. Results. 99.1% of isolates were susceptible to Imipenem. For Ertapenem, 4 were resistant and 4 intermediate. The modified Hodge test was positive for all 08 isolates. A minimum inhibitory concentration comparison of K. pneumoniae, E. cloacae, and E. coli for Imipenem has noted a significant difference between E. cloacae on one hand and E. coli, K. pneumoniae on the other hand (P < 0.01). No significant difference was noted for minimum inhibitory concentration of Ertapenem. Conclusion. Our results confirm in vitro effectiveness of Ertapenem against extended spectrum beta-lactamase-producing Enterobacteriaceae as reported elsewhere. However, the emergence of resistance to Carbapenems revealed by production of carbapenemases in this study confirmed a necessary bacteriological documented infection before using Ertapenem.

δ-Carbolines and their ring-opened analogs: synthesis and evaluation against fungal and bacterial opportunistic pathogens

Previous studies have indicated that the δ-carboline (2) ring system derived from the natural product cryptolepine (1) may represent a pharmacophore for anti-infective activity. This paper describes the design and synthesis of a small library of substituted δ-carbolines and the evaluation of the anti-fungal and anti-bacterial activities. An evaluation of the anti-bacterial activity of a previously reported library of ring-opened analogs was also conducted to provide an opportunity to test the hypothesis that both group of compounds may have the same biological target. Results indicate that against a selected group of fungal pathogens, substituted δ-carbolinium analogs displayed higher potency and several fold lower cytotoxicity than cryptolepine the parent natural product. Both the δ-carbolinium compounds and their ring-opened analogs, exhibited equally high anti-bacterial activity against the selected pathogens and especially against the gram positive bacteria evaluated.

Control of health care-associated infections (HAI): winning both the battles and the war

At present, the United States (US) experiences its greatest life expectancy due mainly to improvements in mortality from cardiovascular diseases, which include coronary heart disease and stroke. These, in turn, are due largely to decreases in cigarette smoking as well as earlier and more aggressive diagnoses and treatments. These advances in health care delivery are, not surprisingly, accompanied by increasing numbers of complicating health care-associated infections (HAI). HAIs are a major and increasing cause of morbidity and mortality in the US as well as around the world. To win both the battles and the war against HAI requires a multidisciplinary approach to the vigorous implementation and maintenance of proper infection control procedures. This should include continuous surveillance and reinforcement of guidelines to enhance evidence-based practices to prevent and control HAI. It will also be necessary to implement a new paradigm of early and formal education of future health care providers into the biology of infection as well as the principles of infection control in the classroom and subsequently, with translation into their clinical training. Finally, there must also be the incorporation and expansion of continuing medical education for established health care providers about prevention and control of HAI.