[Epidemiology of nosocomial infections due to Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia]

Analysis of the Microbiota of the Physiotherapist's Environment

OBJECTIVES

To analyze the microbiota of the physiotherapist's work environment to understand the existing potential risks and to adopt appropriate preventive measures.

DESIGN

Cross-sectional descriptive observational study.

SETTING

Physiotherapist's working environment.

PARTICIPANTS

Physiotherapy and rehabilitation centers (N=19).

INTERVENTIONS

A microbiological sampling was carried out in the physiotherapy centers. The samples were studied using the usual culture and analysis methodology for characterization and isolation of a range of bacteria.

MAIN OUTCOME MEASURES

Absolute and relative frequency of microorganism isolation.

RESULTS

In the analysis, pathogens normally responsible for nosocomial infections were detected, especially on instruments and equipment used by the physiotherapist such as sponge electrodes, and were significantly more contaminated than the rest of the places studied (P<.01).

CONCLUSION

This situation confirms the absence of measures and protocols for the prevention and control of such infections in the physiotherapist's environment, which is why they must be considered to protect both physiotherapy professionals and patients.

Investigation of Stenotrophomonas maltophilia epidemiology in a French cystic fibrosis center

BACKGROUND

Stenotrophomonas maltophilia is an emerging opportunistic pathogen. The increasing incidence is of particular concern in patients with cystic fibrosis (CF). Since 2012, the Western France has witnessed high annual prevalence of S. maltophilia colonization/infection. This retrospective cohort study investigated the epidemiology of S. maltophilia emergence in the CF center of Roscoff, Western France, a region of high prevalence of CF in Europe.

METHODS

All CF patients with S. maltophilia isolated in respiratory samples between December 2013 and February 2017 were included. For each patient the colonization status with S. maltophilia was determined. The epidemiological and microbiological characteristics collected were compared between colonization statuses.

RESULTS

S. maltophilia was isolated in 90 patients (42 males, 48 females). Mean age at first colonization was 24.4±13.5 years. Annual prevalence since 2013 was high (16-17.9%), but stable. This high prevalence is mainly due to a high rate of intermittent colonization. Only 2.8% of CF patients showed chronic colonization, with significantly more frequent co-colonization by methicillin-susceptible Staphylococcus aureus (P<0.0001) and Pseudomonas aeruginosa (P<0.05). During chronic colonization, S. maltophilia acquired resistance to cotrimoxazole and β-lactams. Interestingly, there were cases of decolonization.

CONCLUSION

This is the first epidemiological report of S. maltophilia in a French CF center. Prevalence was stable but above the national average. Most cases were intermittent; chronic colonization was rare.

Polyester-based particles to overcome the obstacles of mucus and biofilms in the lung for tobramycin application under static and dynamic fluidic conditions

Pulmonary infections with Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc) are difficult to treat and related with high mortality in some diseases like cystic fibrosis due to the recurrent formation of biofilms. The biofilm formation hinders efficient treatment with inhaled antibiotics due to a low penetration of the antibiotics through the polyanionic biofilm matrix and increased antimicrobial resistance of the biofilm-embedded bacteria. In this study, tobramycin (Tb) was encapsulated in particles based on poly(d,l,-lactide-co-glycolide) (PLGA) and poly(ethylene glycol)-co-poly(d,l,-lactide-co-glycolide) diblock (PEG-PLGA) to overcome the biofilm barrier with particle sizes of 225-231 nm (nanoparticles) and 896-902 nm (microparticles), spherical shape and negative zeta potentials. The effectiveness against biofilms of P. aeruginosa and B. cepacia was strongly enhanced by the encapsulation under fluidic experimental condition as well as under static conditions in artificial mucus. The biofilm-embedded bacteria were killed by less than 0.77 mg/l encapsulated Tb, whereas 1,000 mg/l of free Tb or the bulk mixtures of Tb and the particles were ineffective against the biofilms. Moreover, encapsulated Tb was even effective against biofilms of the intrinsically aminoglycoside-resistant B. cepacia, indicating a supportive effect of PEG and PLGA on Tb. No cytotoxicity was detected in vitro in human lung epithelial cells with any formulation.

Prevalence and antibiotic resistance of Pseudomonas aeruginosa in water samples in central Italy and molecular characterization of oprD in imipenem resistant isolates

Scope

This study aimed to analyse the prevalence, antibiotic resistance and genetic relatedness of P. aeruginosa isolates obtained from potable and recreational water samples (n. 8,351) collected from different settings (swimming pools, n. 207; healthcare facilities, n 1,684; accommodation facilities, n. 1,518; municipal waterworks, n. 4,500; residential buildings, n. 235). Possible mechanisms underlying resistance to imipenem, with particular focus on those involving oprD-based uptake, were also explored.

Methods and results

Isolation and identification of Pseudomonas aeruginosa was performed according to the standardized procedure UNI EN ISO 16266:2008 followed by PCR confirmation. Antibiotic Susceptibility testing was conducted according to EUCAST standardized disk diffusion method. Genetic relatedness of strains was carried out by RAPD. The sequence of the oprD gene was analyzed by standard method. Fifty-three samples (0.63%) were positive for P. aeruginosa, of which 10/207 (4.83%) were from swimming pools. Five isolates (9.43%) were resistant to imipenem, one to Ticarcillin + Clavulanate, one to both Piperacillin and Ticarcillin + Clavulanate. The highest isolation rate of imipenem resistant P. aeruginosa was observed in swimming pool water. Identical RAPD profiles were found in isolates from the same location in the same year or even in different years.

Conclusions

Imipenem resistant strains were identified as carbapenemase-negative and resistance has been associated with inactivating mutations within the oprD gene, with a concomitant loss of porin. RAPD results proved that a water system can remain colonized by one strain for long periods and the contamination may be difficult to eradicate.

This study has revealed the presence of P. aeruginosa in different water samples, including resistant strains, especially in swimming pools, and confirmed the role of porins as a contributing factor in carbapenem resistance in Gram-negative bacteria.

Bacteriophage-based therapy in cystic fibrosis-associated Pseudomonas aeruginosa infections: rationale and current status

Pulmonary infections involving Pseudomonas aeruginosa are among the leading causes of the deterioration of the respiratory status of cystic fibrosis (CF) patients. The emergence of multidrug-resistant strains in such populations, favored by iterative antibiotic cures, has led to the urgent need for new therapies. Among them, bacteriophage-based therapies deserve a focus. One century of empiric use in the ex-USSR countries suggests that bacteriophages may have beneficial effects against a large range of bacterial infections. Interest in bacteriophages has recently renewed in Western countries, and the in vitro data available suggest that bacteriophage-based therapy may be of significant interest for the treatment of pulmonary infections in CF patients. Although the clinical data concerning this specific population are relatively scarce, the beginning of the first large randomized study evaluating bacteriophage-based therapy in burn infections suggests that the time has come to assess the effectiveness of this new therapy in CF P. aeruginosa pneumonia. Consequently, the aim of this review is, after a brief history, to summarize the evidence concerning bacteriophage efficacy against P. aeruginosa and, more specifically, the in vitro studies, animal models, and clinical trials targeting CF.

The impact of aerators on water contamination by emerging gram-negative opportunists in at-risk hospital departments

OBJECTIVE

Our aim was to evaluate the impact of aerators on water microbiological contamination in at-risk hospital departments, with a view to quantifying the possible risk of patient exposure to waterborne microorganisms.

DESIGN

We analyzed the microbiological and chemical-physical characteristics of hot and cold water in some critical hospital departments.

SETTING

Two hospitals in northern Italy.

METHODS

We took 304 water samples over a 1-year period, at 3-month intervals, from taps used by healthcare personnel for handwashing, surgical washing, and the washing of medical equipment. We analyzed heterotrophic plate counts (HPCs) at 36°C and 22°C, nonfastidious gram-negative bacteria (GNB-NE), and Legionella pneumophila.

RESULTS

The percentages of positivity and mean values of HPCs at 22°C, HPCs at 36°C, and GNB-NE loads were significantly higher at outlet points than in the plumbing system. In particular, GNB-NE positivity was higher at outlet points than in the plumbing system in both the cold water (31.58% vs 6.58% of samples were positive) and hot water (21.05% vs 3.95%) supplies. Our results also revealed contamination by L. pneumophila both in the plumbing system and at outlet points, with percentages of positive samples varying according to the serogroup examined (serogroups 1 and 2-14). The mean concentrations displayed statistically significant (P < .001) differences between the outlet points (27,382.89 ± 42,245.33 colony-forming units [cfu]/L) and the plumbing system (19,461.84 ± 29,982.11 cfu/L).

CONCLUSIONS

These results reveal a high level of contamination of aerators by various species of gram-negative opportunists that are potentially very dangerous for immunocompromised patients and, therefore, the need to improve the management of these devices.

Systematic mutational analysis of the putative hydrolase PqsE: toward a deeper molecular understanding of virulence acquisition in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an important opportunistic human pathogen that can establish bacterial communication by synchronizing the behavior of individual cells in a molecular phenomenon known as “quorum sensing”. Through an elusive mechanism involving gene products of the pqs operon, the PqsE enzyme is absolutely required for the synthesis of extracellular phenazines, including the toxic blue pigment pyocyanin, effectively allowing cells to achieve full-fledged virulence. Despite several functional and structural attempts at deciphering the role of this relevant enzymatic drug target, no molecular function has yet been ascribed to PqsE. In the present study, we report a series of alanine scanning experiments aimed at altering the biological function of PqsE, allowing us to uncover key amino acid positions involved in the molecular function of this enzyme. We use sequence analysis and structural overlays with members of homologous folds to pinpoint critical positions located in the vicinity of the ligand binding cleft and surrounding environment, revealing the importance of a unique C-terminal α-helical motif in the molecular function of PqsE. Our results suggest that the active site of the enzyme involves residues that extend further into the hydrophobic core of the protein, advocating for a lid-like movement of the two terminal helices. This information should help design virtual libraries of PqsE inhibitors, providing means to counter P. aeruginosa virulence acquisition and helping to reduce nosocomial infections.

Antibiotic resistance and extended-spectrum β-lactamases in isolated bacteria from seawater of Algiers beaches (Algeria)

The aim of the study was to evaluate bacterial antibiotic resistance in seawater from four beaches in Algiers. The most significant resistance rates were observed for amoxicillin and ticarcillin, whereas they were relatively low for ceftazidime, cefotaxime and imipenem. According to sampling sites, the highest resistance rates were recorded for 2 sites subjected to chemical and microbiological inputs (amoxicillin, 43% and 52%; ticarcillin, 19.6% and 47.7%), and for 2 sites relatively preserved from anthropogenic influence, resistance rates were lowest (amoxicillin, 1.5% and 16%; ticarcillin, 0.8% and 2.6%). Thirty-four bacteria resistant to imipenem (n=14) or cefotaxime (n=20) were identified as Pseudomonas aeruginosa (n=15), Pseudomonas fluorescens (7), Stenotrophomonas maltophilia (4), Burkholderia cepacia (2), Bordetella sp. (1), Pantoea sp. (1), Acinetobacter baumannii (1), Chryseomonas luteola (1), Ochrobactrum anthropi (1) and Escherichia coli (1). Screening for extended spectrum β-lactamase showed the presence of CTX-M-15 β-lactamase in the E. coli isolate, and the encoding gene was transferable in association with the IncI1 plasmid of about 50 kbp. Insertion sequence ISEcp1B was located upstream of the CTX-M-15 gene. This work showed a significant level of resistance to antibiotics, mainly among environmental saprophytic bacteria. Transmissible CTX-M-15 was detected in E. coli; this may mean that contamination of the environment by resistant bacteria may cause the spread of resistance genes.

[Stenotrophomonas maltophilia and Pseudomonas aeruginosa water-associated microbiologic risk assessment in Amiens' University Hospital Centre]

BACKGROUND

Pseudomonas aeruginosa (Psa) and Stenotrophomonas maltophilia (Smalto) are major opportunistic waterborne pathogens causing hospital-acquired infections. This study aimed to assess the biocontamination level of cold water used in Amiens' university hospital wards, from March to June 2008.

METHODS

We cultivated 122 pairs of cold water first jet and taps cotton-swabs on Cetrimide agar for Psa, on Stenotrophomonas maltophilia selective medium with coloured indicator (SM2i) for Smalto, on Mueller Hinton agar used as isolation medium reference for both, 48h at 30 degrees C. Data analysed with Epi-Info 6.04dFr were compared with chi(2) test, significant at p<.05.

RESULTS

Psa and Smalto were isolated in 26.2 and 14.8% of water samples and in 21.3 and 10.7% of swab samples respectively. They were associated in 11.5% of water samples and 5% of swab samples. Psa was alone in 13.1% of water samples and 7.4% of swab samples whereas Smalto was found in 6.6% of water and 2.5% of swabs. Psa and Smalto were isolated from 14.8% of water samples and 8.2% of swab samples of the same tap. Finally, respectively 35.2 and 17.2% of the cold water taps were biocontaminated by Psa and Smalto. In fact, microbiologic water taps contamination risk was two-fold higher for Psa than for Smalto, p<.001, without variation between wards.

CONCLUSION

Sm2i and Cetrimide are suited and efficient medium respectively for Smalto and Psa isolation. Cold-water samples are sufficient for waterborne pathogens biocontamination risk appraisal. Our results urged healthcare workers on efficient water fittings microbiologic risk control to prevent healthcare associated waterborne infections, notably due to Psa and Smalto.

Antibiotic susceptibility and mechanisms of beta-lactam resistance among clinical strains of Pseudomonas aeruginosa: first report in Algeria

OBJECTIVE

Pseudomonas aeruginosa is a major causative agent of hospital infections. Studies on this subject being rare in Algeria, we determined the antibiotic susceptibility of P. aeruginosa and investigated the mechanisms of beta-lactam resistance and the spread of multidrug resistant strains in the university affiliated Hospital of Tlemcen (Algeria).

DESIGN

One hundred and ninety-nine consecutive strains of P. aeruginosa were collected between November 2005 and February 2007. MICs of antibiotics were measured by the agar dilution method. The resistance mechanisms to beta-lactams were identified phenotypically or by molecular methods (isoelectrofocusing, PCR and sequencing). Strains expressing a secondary beta-lactamase were serotyped and genotyped (Random Amplified Polymorphic DNA).

RESULTS

The proportion of susceptible isolates were: ticarcillin (56%), piperacillin-tazobactam (81%), ceftazidime (88%), cefepime (80%), aztreonam (64%), imipenem (65%), amikacin (83%), tobramycin (81%) and ciprofloxacin (97%) according to the French CASFM breakpoints. Resistance to beta-lactams was linked to the production of transferable beta-lactamases (16%), overproduction of cephalosporinase AmpC (12%) and/or non-enzymatic mechanisms such as the loss of porin OprD (35%) and overproduction of the active efflux system MexAB-OprM (24%). High level resistance to ticarcillin was due to the expression of beta- lactamase OXA-10 alone or associated with TEM-110. A genotypic analysis revealed the spread of a multidrug resistant epidemic clone expressing these two acquired beta-lactamases in the surgical ICU.

CONCLUSIONS

This study shows that resistance to antibiotics, in particular to imipenem of P. aeruginosa, is becoming a cause of concern in the Hospital of Tlemcen.

Intensive care unit-acquired Stenotrophomonas maltophilia: incidence, risk factors, and outcome

Introduction

The aim of this study was to determine incidence, risk factors, and impact on outcome of intensive care unit (ICU)-acquired Stenotrophomonas maltophilia.

Methods

This prospective observational case-control study, which was a part of a cohort study, was conducted in a 30-bed ICU during a three year period. All immunocompetent patients hospitalised >48 hours were eligible. Patients with non-fermenting Gram-negative bacilli (NF-GNB) at ICU admission were excluded. Patients without ICU-acquired S. maltophilia who developed an ICU-acquired NF-GNB other than S. maltophilia were also excluded. Screening (tracheal aspirate and skin, anal, and nasal swabs) for NF-GNB was performed in all patients at ICU admission and weekly. Univariate and multivariate analyses were performed to determine risk factors for ICU-acquired S. maltophilia and for ICU mortality.

Results

Thirty-eight (2%) patients developed an S. maltophilia ICU-acquired colonisation and/or infection and were all successfully matched with 76 controls. Chronic obstructive pulmonary disease (COPD) and duration of antibiotic treatment (odds ratio [OR] [95% confidence interval (CI)] = 9.4 [3 to 29], p < 0.001, and 1.4 [1 to 2.3], p = 0.001, respectively) were independently associated with ICU-acquired S. maltophilia. Mortality rate (60% versus 40%, OR [95% CI] = 1.3 [1 to 1.7, p = 0.037]), duration of mechanical ventilation (23 ± 16 versus 7 ± 11 days, p < 0.001), and duration of ICU stay (29 ± 21 versus 15 ± 17 days, p < 0.001) were significantly higher in cases than in controls. In addition, ICU-acquired infection related to S. maltophilia was independently associated with ICU mortality (OR [95% CI] = 2.8 [1 to 7.7], p = 0.044).

Conclusion

COPD and duration of antibiotic treatment are independent risk factors for ICU-acquired S. maltophilia. ICU-acquired S. maltophilia is associated with increased morbidity and mortality rates. ICU-acquired infection related to S. maltophilia is an independent risk factor for ICU mortality.