The global threat of antimicrobial resistance: science for intervention

In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.

In vitro selection of mutants resistant to ozenoxacin compared with levofloxacin and ciprofloxacin in Gram-positive cocci

OBJECTIVES

To determine the frequency of selecting mutants resistant to ozenoxacin, a des-fluoro-(6)-quinolone active against pathogens involved in skin and skin structure infections, compared with levofloxacin and ciprofloxacin in quinolone-susceptible and -resistant Gram-positive cocci.

METHODS

Forty-nine quinolone-susceptible and -resistant Gram-positive cocci strains with different profiles of mutations in the quinolone resistance-determining region (QRDR) were examined to determine the frequency of selecting mutants resistant to ozenoxacin compared with levofloxacin and ciprofloxacin. MICs and mutations in the QRDR were determined by standard broth microdilution and PCR amplification and sequencing, respectively.

RESULTS

The mean resistance rates were 3.8 × 10(-9) (range <9 × 10(-11)-1 × 10(-8)) for ozenoxacin, 9.7 × 10(-9) (range <1.1 × 10(-11)-4.2 × 10(-8)) for levofloxacin and 1.2 × 10(-8) (range <1.6 × 10(-10)-2.6 × 10(-7)) for ciprofloxacin. Spontaneous mutants resistant to ozenoxacin showed lower MICs (≤ 16 mg/L) than mutants resistant to levofloxacin and ciprofloxacin (≤ 512 mg/L). Additional mutations were observed only in ParC at Ser-80 in Staphylococcus spp., Ser-79 in Streptococcus agalactiae and Asp-83 and Ser-89 in Streptococcus pyogenes.

CONCLUSIONS

The probability of ozenoxacin selecting spontaneous resistant mutants in quinolone-susceptible and -resistant strains with pre-existing mutations in the QRDR is low, supporting the potential utility of ozenoxacin as a therapeutic alternative in the treatment of skin infections caused by strains highly resistant to quinolones.

Monotherapy versus combination therapy for sepsis due to multidrug-resistant Acinetobacter baumannii: analysis of a multicentre prospective cohort

BACKGROUND

Treatment of multidrug-resistant Acinetobacter baumannii (MDRAB) infection presents a challenge because of the scarcity of available options. Even though combination therapy (CT) is frequently used in clinical practice, data are needed to support its use instead of monotherapy (MT).

METHODS

A prospective observational study was conducted in 28 Spanish hospitals. Patients with sepsis caused by MDRAB, defined according to strict criteria, and who received active antibiotic treatment (according to in vitro susceptibility testing) for at least 48 h, were included. The main outcome variable was all-cause 30 day mortality after initiation of targeted therapy. Multivariate analysis, including a propensity score (for receiving CT), was performed by Cox regression.

RESULTS

One hundred and one patients were included in the analysis; 68 (67.3%) received MT and 33 (32.7%) received CT. Pneumonia was the most common infection (50.5%), 68.6% of cases being associated with mechanical ventilation. Colistin (67.6%) and carbapenems (14.7%) were the most common drugs used in MT; colistin plus tigecycline (27.3%) and carbapenem plus tigecycline (12.1%) were the most frequent combinations. Crude 30 day mortality was 23.5% and 24.2% for the MT and CT groups, respectively (RR = 1.03; 95% CI 0.49-2.16; P = 0.94). Multivariate analysis of 30 day survival showed no trend towards reduced 30 day mortality with CT (HR = 1.35; 95% CI 0.53-3.44; P = 0.53). Subgroup analysis showed similar results.

CONCLUSIONS

Our data do not support an association of CT with reduced mortality in MDRAB infections. More data for specific types of infection and combinations are needed.

Aetiology of traveller's diarrhoea: evaluation of a multiplex PCR tool to detect different enteropathogens

Traveller's diarrhoea (TD) is the most common illness reported in international travellers. TD is caused by a wide range of pathogens, including bacteria, viruses and parasites. Multiplex PCR assays can be especially useful for studying the aetiology of TD. The first objective of this study was to evaluate the utility of the commercially available multiplex PCR (xTAG(®) Gastrointestinal Pathogen Panel (GPP)) for the diagnosis of TD. A total of 185 stool specimens obtained from 174 patients were processed using the GPP assay. This test detected 86 pathogens in 67 stool samples (67/185, 36.2%). Sixteen pathogens out of 86 were also detected by routine testing. The remaining pathogens (n = 70) required further confirmation by alternative techniques. Finally, 60 out of 70 pathogens were confirmed. The second objective of this study was to analyse the aetiology of TD based on the results obtained by the GPP test and routine methods. The primary pathogens causing TD were Shigella (24.2%) followed by enterotoxigenic Escherichia coli (ETEC) (23.2%), enteroaggregative E. coli (14.7%) and Giardia (13.7%). Significant regional differences were observed for ETEC with 19.4% of TD cases acquired in Africa, 11.3% in Asia and none in South Central (SC) America (p 0.01), Giardia was found in 1.5% of cases among those who had travelled to Africa, 14.1% of those who had travelled to Asia and 3% of those who had travelled to SC America (p 0.01). In conclusion, the GPP test improved the detection of enteropathogens and allowed better assessment of the aetiology of TD.

Lack of detection of Middle East respiratory syndrome coronavirus in mild and severe respiratory infections in Catalonia, northeastern Spain

Surveillance of Middle East respiratory syndrome coronavirus (MERS-CoV) was conducted to explore the possible introduction and circulation of this novel virus in Catalonia, northeastern Spain. Five hundred and sixty-three samples from mild and severe respiratory infections collected between January 2012 and April 2013 were screened using real-time RT-PCR. All samples were negative, suggesting that MERS-CoV is not circulating silently in Catalonia.

The effects of superovulation of donor sows on ovarian response and embryo development after nonsurgical deep-uterine embryo transfer

This study aimed to evaluate the effectiveness of superovulation protocols in improving the efficiency of embryo donors for porcine nonsurgical deep-uterine (NsDU) embryo transfer (ET) programs. After weaning (24 hours), purebred Duroc sows (2-6 parity) were treated with 1000 IU (n = 27) or 1500 IU (n = 27) of eCG. Only sows with clear signs of estrus 4 to 72 hours after eCG administration were treated with 750 IU hCG at the onset of estrus. Nonhormonally treated postweaning estrus sows (n = 36) were used as a control. Sows were inseminated and subjected to laparotomy on Days 5 to 6 (Day 0 = onset of estrus). Three sows (11.1%) treated with the highest dosage of eCG presented with polycystic ovaries without signs of ovulation. The remaining sows from nonsuperovulated and superovulated groups were all pregnant, with no differences in fertilization rates among groups. The number of CLs and viable embryos was higher (P < 0.05) in the superovulated groups compared with the controls and increased (P < 0.05) with increasing doses of eCG. There were no differences among groups in the number of oocytes and/or degenerated embryos. The number of transferable embryos (morulae and unhatched blastocysts) obtained in pregnant sows was higher (P < 0.05) in the superovulated groups than in the control group. In all groups, there was a significant correlation between the number of CLs and the number of viable and transferable embryos, but the number of CLs and the number of oocytes and/or degenerated embryos were not correlated. A total of 46 NsDU ETs were performed in nonhormonally treated recipient sows, with embryos (30 embryos per transfer) recovered from the 1000-IU eCG, 1500-IU eCG, and control groups. In total, pregnancy and farrowing rates were 75.1% and 73.2%, respectively, with a litter size of 9.4 ± 0.6 piglets born, of which 8.8 ± 0.5 were born alive. There were no differences for any of the reproductive parameters evaluated among groups. In conclusion, our results demonstrated the efficiency of eCG superovulation treatments in decreasing the donor-to-recipient ratio. Compared with nonsuperovulated sows, the number of transferable embryos was increased in superovulated sows without affecting their quality and in vivo capacity to develop to term after transfer. The results from this study also demonstrate the effectiveness of the NsDU ET procedure used, making possible the commercial use of ET technology by the pig industry.

Comparison of acquisition of resistant microorganisms and infections in critically-ill patients with and without malignancies

BACKGROUND

Patients with malignancies are often considered at risk of acquiring infections by resistant or potentially resistant microorganisms (RPRMs). However, data supporting this contention is scarce. We have compared critically ill patients with haematological malignancies (HM), solid tumours (ST) and without cancer (NC) in terms of acquisition of RPRMs, infections and mortality.

METHODS

Observational, prospective cohort study of patients admitted to a medical intensive care unit (ICU). Swabbing of nares, pharynx and rectum, and culture of respiratory secretions were obtained within 48 h of admission and thrice weekly thereafter. Clinical samples were obtained as deemed necessary by the attending physician. Clinical variables, severity scores on admission and exposures during ICU stay were also collected. Multivariable logistic regression analysis was used to evaluate ICU mortality.

RESULTS

Out of 969 included patients 127 (13.1%) had HM and 93 (9.6%) had ST. Patients with malignancies were more frequently exposed to central venous catheterization, methylprednisolone, and any antipseudomonal antibiotic whereas they were less commonly exposed to invasive mechanical ventilation. Patients with HM were more often admitted with an infection. There were no differences among groups in terms of RPRMs acquisition during ICU stay or prevalence of ICU-acquired infections due to any microorganism, including RPRMs. Having a HM was an independent predictor of mortality regardless of APACHE II score.

CONCLUSION

Critically ill cancer patients did not show a higher rate of RPRMs acquisition nor ICU-acquired infections. Mortality was higher in the HM group and it was not accurately predicted on admission by APACHE II score.

Antimicrobial resistance in Shigella spp. causing traveller's diarrhoea (1995-2010): a retrospective analysis

BACKGROUND

Shigellosis is a global human health problem causing an important morbidity among travellers returning from tropical areas. This study was aimed to describe the evolution of antimicrobial resistance profile in Shigella spp. isolated between the years 1995-2010 in patients with traveller's diarrhoea (TD) returning from tropical areas.

METHODS

The levels of antimicrobial resistance were tested in a total of 191 Shigella spp. isolated during the period from 1995 to 2010.

RESULTS

A decrease of cases of diarrhoea caused by Shigella has been observed in recent years. A wide spectrum of antibiotic resistance was observed among Shigella spp. These isolates showed high levels of resistance to tetracycline (84%), co-trimoxazole (75.5%), and ampicillin (45.5%). The resistance was low to ciprofloxacin (2.1%), azithromycin (3.9%) and furazolidone (8.4%). According to the period, in the case of ampicillin, amoxicillin plus clavulanic acid, chloramphenicol, values of resistance were significantly decreasing from 1995-2000 to 2001-2010, (62.5% vs. 28.4%, 19.8% vs. 6.6%, 23.4 vs. 10.4%, respectively). Meanwhile in nalidixic acid and tetracycline the evolution of resistance has increased over time.

CONCLUSIONS

A decrease in the isolation number of Shigella spp. causing TD has been observed. Differential trends in the evolution of the levels of resistance to the tested antibacterial agents have been observed.

Electrical conductivity of seven binary systems containing 1-ethyl-3-methyl imidazolium alkyl sulfate ionic liquids with water or ethanol at four temperatures

We present experimental measurements of specific electrical (or ionic) conductivity of seven binary systems of 1-ethyl-3-methyl imidazolium alkyl sulfate (EMIM-C(n)S) with water or ethanol. Electrical conductivity was measured at 298.15 K in all ranges of concentrations and selected mixtures also at 288.15, 308.15, and 318.15 K. The alkyl chains of the anions used are ethyl (EMIM-ES), butyl (EMIM-BS), hexyl (EMIM-HS), and, only for mixtures with ethanol, octyl (EMIM-OS). Let us note that the four ionic liquids (ILs) measured are miscible in water and ethanol at those temperatures and atmospheric pressure in all ranges of concentrations, but EMIM-OS jellifies for a given range of concentration with water. We compare the measured data in terms of the alkyl chain length and solvent nature. Data are compared with previously scarce results for these same systems and also for other aqueous and ethanol mixtures with ILs. In addition, we verify that our data fit the universal theoretical expression with no fitting parameters given by the pseudolattice-based Bahe-Varela model, except for IL concentrated mixtures. To fit well all ranges of concentrations, we add to the original equation two phenomenological terms with one fitting parameter each. Finally, we calculate the molar conductivity and fit it successfully with an expression derived from Onsager theory.