Screening for ß-lactam resistance by penicillin G in the Streptococcus anginosus group challenged by rare strains with altered PBPs.

BACKGROUND: Streptococcus anginosus group (SAG) strains are common pathogens causing abscesses and bacteraemia. They are generally susceptible to ß-lactams, which constitute first-line treatment. EUCAST recommends testing penicillin G susceptibility to screen for ß-lactam resistance. Isolates categorized as susceptible (negative screening) can be reported as susceptible to aminopenicillins and third-generation cephalosporins. OBJECTIVES: To assess the reliability of penicillin G resistance screening in predicting ß-lactam resistance in SAG blood culture isolates, and to investigate isolates for which this test would be unreliable. METHODS: We determined the susceptibility to penicillin G, amoxicillin and ceftriaxone of 90 SAG blood culture isolates, all with negative penicillin G resistance screening. ß-Lactam-resistant strains were sequenced and compared with susceptible reference SAG strains. RESULTS: We detected two isolates displaying ß-lactam resistance, especially to third-generation cephalosporins, despite negative screening for penicillin G resistance. For these isolates, amino acid substitutions were identified next to the essential PBP motifs SxxK, SxN and/or KS/TGS/T. Changes in these motifs have been previously linked to ß-lactam resistance in Streptococcus pneumoniae. CONCLUSIONS: Our study suggests that aminopenicillin and third-generation cephalosporin susceptibility should be determined for SAG strains in the event of severe infection as screening for penicillin G resistance might not be sufficient to detect resistance mechanisms that predominantly affect cephalosporins. The PBP sequencing of resistant SAG strains allowed us to detect amino acid changes potentially linked to ß-lactam resistance.

Outcome of community- versus hospital-acquired intra-abdominal infections in intensive care unit: a retrospective study.

BACKGROUND: To compare patients hospitalised in the intensive care unit (ICU) after surgery for community-acquired intra-abdominal infection (CA-IAI) and hospital-acquired intra-abdominal infection (HA-IAI) in terms of mortality, severity and complications. METHODS: Retrospective study including all patients admitted to 2 ICUs within 48 h of undergoing surgery for peritonitis. RESULTS: Two hundred twenty-six patients were enrolled during the study period. Patients with CA-IAI had an increased 28-day mortality rate compared to those with HA-IAI (30% vs 15%, respectively (p = 0.009)). At 90 days, the mortality rates were 36.7 and 37.5% in the CA-IAI group and HA-IAI group, respectively, with a similar APACHE II score on admission (median: 21 [15-25] vs. 21 [15-24] respectively, p = 0.63). The patients with HA-IAI had prolonged ICU and hospital stays (median: 17 [7-36] vs. 6[3-12] days, p < 0.001 and 41 [24-66] vs. 17 [7-32] days, p = 0.001), and experienced more complications (reoperation and reintubation) than those with CA-IAI. CONCLUSION: CA-IAI group had higher 28-day mortality rate than HA-IAI group. Mortality was similar at 90 days but those with HA-IAI had a prolonged ICU and hospital stay. In addition, they developed more complications.

Risk factors for acquisition of carbapenem-resistance during treatment with carbapenem in the intensive care unit: a prospective study.

The emergence of carbapenemases in gram-negative aerobes is worrying. The aim of this prospective study was to estimate the incidence of acquisition of carbapenem-resistance during treatment in ICU and to identify the risk factors. This was a prospective, observational, cohort study. This study was conducted at intensive care unit, academic medical center, Toulouse Rangueil University Hospital. Patients were included if they received antibiotic treatment with carbapenem for more than 48 h. Biological samples were taken in accordance with current practice in the unit. The main endpoint was the occurrence of bacterial resistance to carbapenems occurring between the onset of treatment and the patient's exit from the ICU. Uni- and multi-variate analyses were carried out. Of the 364 patients admitted to the unit between May and November 2014, 78 were included in our study and 16 (20.51%) developed resistance. The two main risk factors were a length of stay in ICU of more than 29 days (HR = 3.61, p = 0.01) and the presence of Pseudomonas aeruginosa in the samples taken before the start of treatment (HR = 5.31, p = 0.002). No resistance due to carbapenemase production was observed in this study. The prescription of carbapenems in the ICU setting must adhere to the expert guidelines. In light of our results, special attention must be paid to patients whose stay in intensive care is prolonged, and those in whom Pseudomonas aeruginosa is isolated from bacteriological samples taken before the beginning of antibiotic therapy.

Efficacy of teicoplanin monotherapy following initial standard therapy in Enterococcus faecalis infective endocarditis: a retrospective cohort study.

PURPOSE: Teicoplanin is often used in Enterococcus faecalis infective endocarditis as a relay in case of penicillin side effects, or in outpatients. We assessed the efficacy of teicoplanin used as continuation therapy after initial standard treatment of E. faecalis endocarditis. METHODS: All adult patients consecutively diagnosed between 1997 and 2016 for E. faecalis endocarditis were retrospectively reviewed. Patients who received standard therapy (ST) were compared to those switched to teicoplanin to complete the treatment (teicoplanin therapy, TT). RESULTS: Seventy-one patients were enrolled: 34 in the ST group and 37 in the TT group. Amoxicillin was replaced by teicoplanin after a median duration of 18 days (IQ25 - 75 12-21). Teicoplanin (5.8 ± 2.3 mg/kg) was administered for a median duration of 29 days (IQ25 - 75 25-34). Gentamicin therapy was similar. Overall duration of antimicrobial therapy was 42 days (IQ25 - 75 35-43) in the ST group, and 46 days (IQ25 - 75 43-49) in the TT group (p = 0.001). Global and endocarditis-related mortality rates were 22/34 (65%) and 13/34 (38%) in the ST group, and 14/37 (38%) and 3/37 (8%) in the TT group (p ≤ 0.05). Relapses occurred in 2/26 patients who survived the treatment phase in the ST group (8%) and in 3/37 in the TT group (8%, p = 0.68). All relapses in the TT group occurred in patients presenting prosthetic valve endocarditis. Finally, 20 patients were cured in the ST group (59%), and 33 patients in the TT group (89%, p = 0.003). CONCLUSIONS: In E. faecalis endocarditis, the switch to teicoplanin in selected patients following an initial phase of standard treatment represents an alternative, particularly for outpatient therapy. Caution should be exercised in cases of prosthetic valve endocarditis.

Fight Against Antimicrobial Resistance: We Always Need New Antibacterials but for Right Bacteria.

Antimicrobial resistance in bacteria is frightening, especially resistance in Gram-negative Bacteria (GNB). In 2017, the World Health Organization (WHO) published a list of 12 bacteria that represent a threat to human health, and among these, a majority of GNB. Antibiotic resistance is a complex and relatively old phenomenon that is the consequence of several factors. The first factor is the vertiginous drop in research and development of new antibacterials. In fact, many companies simply stop this R&D activity. The finding is simple: there are enough antibiotics to treat the different types of infection that clinicians face. The second factor is the appearance and spread of resistant or even multidrug-resistant bacteria. For a long time, this situation remained rather confidential, almost anecdotal. It was not until the end of the 1980s that awareness emerged. It was the time of Vancomycin-Resistance Enterococci (VRE), and the threat of Vancomycin-Resistant MRSA (Methicillin-Resistant Staphylococcus aureus). After this, there has been renewed interest but only in anti-Gram positive antibacterials. Today, the threat is GNB, and we have no new molecules with innovative mechanism of action to fight effectively against these bugs. However, the war against antimicrobial resistance is not lost. We must continue the fight, which requires a better knowledge of the mechanisms of action of anti-infectious agents and concomitantly the mechanisms of resistance of infectious agents.

Binary Enterotoxin Producing Clostridium perfringens Isolated in Blood Cultures: Case Report and Review of the Literature.

Clostridium perfringens (C. perfringens) is an anaerobic, spore-forming Gram-positive rod responsible for necrotizing gangrene, bacteremia in patients with cancer or gastrointestinal tract infection. C. perfringens virulence is due in large part to toxin production. In 2014, a new enterotoxin, BEC (binary enterotoxin of Clostridium perfringens) encoded by becA and becB genes, distinct from enterotoxin (CPE) encoded by the cpe gene, has been described. BEC-producing strains can be causative agents of acute gastroenteritis in humans. We present herein the case of a 64-year-old man who presented to the emergency department of Toulouse University Hospital with pneumonia and septic shock, without digestive symptoms. Blood cultures showed C. perfringens bacteremia and despite appropriate antibiotic treatment the patient passed away 7 h after admission. The characterization of the strain by whole genome sequencing revealed the presence of typical genes of C. perfringens: plc gene (alpha-toxin, phospholipase C) and pfoA (theta-toxin, perfringolysine). Surprisingly, this strain also harbored becA and becB genes encoding the recently described BEC toxin. Interestingly, alpha-toxin typing of our isolate and other published BEC isolates showed that they belonged to different PLC subtypes, confirming the high genetic diversity of these strains. To our knowledge, it is the first clinical case reporting bacteremia due to a BEC-producing C. perfringens isolate.

Long-term hepatitis B surface antigen (HBsAg) kinetics during nucleoside/nucleotide analogue therapy: finite treatment duration unlikely.

BACKGROUND & AIMS: Information regarding long-term HBsAg kinetics during treatment with nucleoside/nucleotide analogues is limited. The aim of the present study was to assess whether finite nucleoside/nucleotide analogue treatment duration could be envisaged during the patient's lifetime. METHODS: Patients with chronic hepatitis B receiving different schedules of nucleoside/nucleotide analogues were followed for a median duration of 102 months, i.e., 8.5 years (interquartile range: 88-119 months). Long-term HBV DNA and HBsAg level kinetics were modeled in order to estimate time to clear HBsAg during therapy in patients with undetectable HBV DNA. RESULTS: Antiviral therapy was associated with a slow but consistent reduction in the level of HBsAg in most of the patients. Three patterns of HBsAg level declines were identified: decline during both the detectable and undetectable HBV DNA phases; decline during the HBV DNA detectable period only; decline during the HBV DNA undetectable period only. The mean HBsAg titer at the time when HBV DNA became undetectable was 3.29 ± 0.49 Log10 international units (IU)/ml, and the mean slope was -0.007 ± 0.007 Log10 IU/month, i.e., an average decline of 0.084 Log10 IU/year. The corresponding calculated median number of years needed to clear HBsAg was 52.2 years (interquartile range: 30.8-142.7). CONCLUSIONS: This study, based on the very long-term follow-up of patients with chronic hepatitis B treated with potent nucleoside/nucleotide analogues, shows that HBsAg clearance is unlikely to occur during the patient's lifetime, even if HBV replication is well controlled. Thus, lifetime therapy is required in the vast majority of HBV-infected patients.

Performances of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for rapid identification of bacteria in routine clinical microbiology.

Rapid and cost-effective matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based systems will replace conventional phenotypic methods for routine identification of bacteria. We report here the first evaluation of the new MALDI-TOF MS-based Vitek MS system in a large clinical microbiology laboratory. This system uses an original spectrum classifier algorithm and a specific database designed for the identification of clinically relevant species. We have tested 767 routine clinical isolates representative of 50 genera and 124 species. Vitek MS-based identifications were performed by means of a single deposit on a MALDI disposable target without any prior extraction step and compared with reference identifications obtained mainly with the VITEK2 phenotypic system; if the identifications were discordant, molecular techniques provided reference identifications. The Vitek MS system provided 96.2% correct identifications to the species level (86.7%), to the genus level (8.2%), or within a range of species belonging to different genera (1.3%). Conversely, 1.3% of isolates were misidentified and 2.5% were unidentified, partly because the species was not included in the database; a second deposit provided a successful identification for 0.8% of isolates unidentified with the first deposit. The Vitek MS system is a simple, convenient, and accurate method for routine bacterial identification with a single deposit, considering the high bacterial diversity studied and as evidenced by the low prevalence of species without correct identification. In addition to a second deposit in uncommon cases, expanding the spectral database is expected to further enhance performances.

Nanoscale effects of antibiotics on P. aeruginosa.

Studying living bacteria at the nanoscale in their native liquid environment opens an unexplored landscape. We focus on Pseudomonas aeruginosa and demonstrate how the cell wall is biophysically affected at the nanoscale by two reference antibiotics (ticarcillin and tobramycin). The elasticity of the cells drops dramatically after treatment (from 263 ± 70 kPa to 50 ± 18 and 24 ± 4 kPa, respectively on ticarcillin- and tobramycin-treated bacteria) and major micro- and nano-morphological modifications are observed (the surface roughness of native, ticarcillin- and tobramycin-treated bacteria are respectively 2.5, 0.8, and 4.4 nm for a surface area of 40,000 nm²). Thus the nanoscale approach in liquid is valid and can be extended. FROM THE CLINICAL EDITOR: Pseudomonas aeruginosa cell wall was demonstrated to be biophysically affected at the nanoscale by two reference antibiotics, ticarcillin, and tobramycin, with the elasticity dropping dramatically after treatment.

Co-Infection and Ventilator-Associated Pneumonia in Critically Ill COVID-19 Patients Requiring Mechanical Ventilation: A Retrospective Cohort Study.

Considering virus-related and drug-induced immunocompromised status of critically ill COVID-19 patients, we hypothesize that these patients would more frequently develop ventilator-associated pneumonia (VAP) than patients with ARDS from other viral causes. We conducted a retrospective observational study in two intensive care units (ICUs) from France, between 2017 and 2020. We compared bacterial co-infection at ICU admission and throughout the disease course of two retrospective longitudinally sampled groups of critically ill patients, who were admitted to ICU for either H1N1 or SARS-CoV-2 respiratory infection and depicted moderate-to-severe ARDS criteria upon admission. Sixty patients in the H1N1 group and 65 in the COVID-19 group were included in the study. Bacterial co-infection at the endotracheal intubation time was diagnosed in 33% of H1N1 and 16% COVID-19 patients (p = 0.08). The VAP incidence per 100 days of mechanical ventilation was 3.4 (2.2−5.2) in the H1N1 group and 7.2 (5.3−9.6) in the COVID-19 group (p < 0.004). The HR to develop VAP was of 2.33 (1.34−4.04) higher in the COVID-19 group (p = 0.002). Ten percent of H1N1 patients and 30% of the COVID-19 patients had a second episode of VAP (p = 0.013). COVID-19 patients have fewer bacterial co-infections upon admission, but the incidence of secondary infections increased faster in this group compared to H1N1 patients.

p-Guanidinoethyl calixarene and parent phenol derivatives exhibiting antibacterial activities. Synthesis and biological evaluation.

The tetra-para-guanidinoethyl-calix[4]arene, its distally-disubstituted ether derivatives involving 2,2'-bithiazolyl- or 2,2'-bipyridyl-methyl groups, as well as the para-guanidinoethylphenol and its analogous derivatives have been synthesized, fully characterized and evaluated as antibacterial agents towards both gram positive and gram negative reference bacteria. The simple phenolic species showed lower activity than their calixarene analogues, confirming the hypothesis that a synergistic effect should result from the spatial organization of guanidinium and heterocycles on a macrocyclic scaffold. Introduction of the bithiazole and bipyridine substituents enhanced the activity of simple phenol derivatives, reaching, for the two Staphylococcus aureus strains in particular, the values obtained for their calixarenic parents. MTT viability assays were carried out to determine selectivity indexes.

Risk factors and the resistance mechanisms involved in Pseudomonas aeruginosa mutation in critically ill patients.

BACKGROUND: The objective of this study was to determine the main risk factors of Pseudomonas aeruginosa mutation as well as the mechanisms of acquired resistance. METHODS: We conducted a 2-year prospective study in patients who were carriers of a Pseudomonas aeruginosa strain and who had been admitted to a medical/surgical ICU. RESULTS: Of the 153 patients who were included, 34 had a mutation in their strain. In a multivariate analysis, a duration of ventilation > 24 days was a risk factor for mutation (risk ratio 4.29; CI 95% 1.94-9.49) while initial resistance was a protective factor (RR 0.36; CI 95% 0.18-0.71). In a univariate analysis, exposure of P. aeruginosa to ceftazidime was associated with an over-production of AmpC cephalosporinase and exposure to meropenem was associated with impermeability. A segmentation method based on the duration of ventilation (> 24 days), initial resistance, and exposure of strains to ceftazidime made it possible to predict at 83% the occurrence of mutation. CONCLUSION: The duration of ventilation and the presence of resistance as soon as P. aeruginosa is identified are predictive factors of mutation in ICU patients.

The CRIOAc healthcare network in France: A nationwide Health Ministry program to improve the management of bone and joint infection.

BACKGROUND: Bone and joint infections (BJIs) have a major clinical and economic impact in industrialized countries. Its management requires a multidisciplinary approach, and a great experience for the most complicated cases to limit treatment failure, motor disability and amputation risk. To our best knowledge there is not currently national specific organization dedicated to manage BJI. Is it possible to build at a national level, a network involving orthopaedic surgeons, infectiologists and microbiologists performing locally multidisciplinary meetings to facilitate the recruitment and the management of patients with complex bone and joint infection in regional centers? HYPOTHESIS: A national healthcare network with regional labeled centers creates a dynamic that improves the recruitment, the management, the education, and the clinical research in the field of complex BJI. PATIENTS AND METHODS: We describe the history of this unique national healthcare network and how it works, specify the missions confided to the CRIOAcs, evaluate the activity of the network over the first decade, and finally discuss perspectives. RESULTS: The labelling of 24 centers in the CRIOAc network allowed for a meshing of the territory, with the possibility of management of complex BJI in each region of France. A dedicated secure national online information system was designed and used to facilitate decision-making during multidisciplinary consultation meetings. Since October 2012 to June 2017, 4553 multidisciplinary consultation meetings have been performed in the structures belonging to the network, with 34,607 cases discussed in 19,961 individual. Prosthetic joint infections represented 38% (7585/19,961) of all BJIs. Among all the cases discussed, the rate of complexity was of 61% (21,110/34,607) (related to antibiotic resistance, infection recurrence, patient co morbidities). A national scientific meeting was created and a national postgraduate diploma in the field of BJI was launched in 2014. The promotion of education, clinical research and interactivity between each academic discipline and between each labeled centers across the country has synergized the strengths and have greatly facilitated the management of patients with BJI. DISCUSSION: The setting up of the CRIOAc network in France took time, and has a cost for the French Ministry of Health. However, this network has greatly facilitated the management of BJI in France, and allowed to concentrate the management of complex BJI in centers that have significantly gained skills. There is, to our knowledge, no other exemple of such nationwide network in the field of BJI. LEVEL OF EVIDENCE: IV, case series without control group.

Tetrazolium salts for MIC determination in microplates: why? Which salt to select? How?

We reported evaluation of a colorimetric MIC assessment for routine susceptibility testing of non-fastidious bacteria, with addition of growth indicators (INT and MTT). Our results made us postulate that the use of such indicators was unnecessary for MIC determination in routine microdilution method.

Ursolic, oleanolic and betulinic acids: antibacterial spectra and selectivity indexes.

ETHNOPHARMACOLOGICAL RELEVANCE: Ursolic acid (UA), oleanolic acid (OA) and betulinic acid (BA), three hydroxyl pentacyclic triterpenoic acids (HPTAs) naturally found in a large variety of vegetarian foods, medicinal herbs and plants have been investigated for antibacterial activity. AIM OF THE STUDY: To determine the antibacterial activity of UA, OA and BA, as well as the toxic impact on eukaryotic cells. MATERIALS AND METHODS: Minimum inhibitory concentrations were determined against five reference strains (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 & ATCC 29213, Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853), as well as five antibiotic-resistant clinical isolates. Toxicity was evaluated against MRC-5 and HaCaT cell lines. RESULTS: No antibacterial activity was observed for BA; while OA and more particularly UA, did show a moderate to good antibacterial activity, but limited to Gram-positive bacteria. Nevertheless, OA and UA were devoid of antibacterial activities against clinical isolates. Moreover, viability and cytotoxic assays demonstrated that the three compounds induced a significant cytotoxicity. CONCLUSIONS: Despite of a relative similar chemical structure; UA, OA and BA harboured different antibacterial activities, with more significant ones for UA. However, considering both viability and toxicity values, these compounds seem to have a significant impact on eukaryotic cell viability.

Enhanced culture recovery of Campylobacter with modified Cary-Blair medium: A practical field experience.

Modified Cary-Blair medium derived devices have been implemented in many laboratories to optimize culture recovery of common bacterial enteric pathogens. Our analysis constitutes the first report of routine laboratory experience supporting the idea that the use of such devices enhances Campylobacter recovery from stools.

QuantiFERON-TB Gold In-Tube as help for the diagnosis of tuberculosis in a French pediatric hospital.

The diagnosis of tuberculosis (TB) is difficult in children. The pediatricians are waiting for new and rapid tests that are easy to realize and that are performed better than tuberculin skin test (TST). We presented here the evaluation of QuantiFERON-TB Gold In-Tube (QFT-G IT) in the Children Hospital of Nancy. Fifty-one children were divided into 3 groups: healthy contacts (HC, n = 31), latent TB infection (LTBI, n = 13), and active TB (n = 7). QFT-G IT was positive in 0%, 15%, and 43% of children compared with 3%, 70%, and 57% for TST, respectively, for the HC, LTBI, and active TB groups. Indeterminate QFT-G IT occurred in 14% of the cases, seemed to correlate with young age, and was not explained by preanalytic parameters. In conclusion, despite its objectivity and its higher specificity (especially in Bacille Calmette-Guérin vaccinated children), the real place of QFT-G IT in TB diagnosis in children remains difficult to define.

In vitro activity of para-guanidinoethylcalix[4]arene against susceptible and antibiotic-resistant Gram-negative and Gram-positive bacteria.

OBJECTIVES: Emergence of multidrug-resistant bacteria has encouraged vigorous efforts to develop antimicrobial agents with new mechanisms of action. In this study, the in vitro antibacterial activity of para-guanidinoethylcalix[4]arene was evaluated and compared with that of its constitutive monomer, para-guanidinoethylphenol. Hexamidine, a widely used antiseptic, and synthalin A, an old antidiabetic and anti-trypanosomal compound, were chosen as references. METHODS: MIC and MBC were determined for five reference strains (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and ATCC 29213, Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853), as well as five antibiotic-resistant clinical isolates. Toxicity on MRC-5 and HaCaT eukaryotic cell lines was also evaluated by MTT and Neutral Red assays. RESULTS: No antibacterial activity was observed for para-guanidinoethylphenol (MIC >or= 512 mg/L) and synthalin A (MIC >or= 64 mg/L). Conversely, para-guanidinoethylcalix[4]arene and hexamidine: (i) showed a broad antibacterial spectrum, both on Gram-positive and on Gram-negative bacteria (MIC = 4 mg/L against E. coli and 8 mg/L against S. aureus for para-guanidinoethylcalix[4]arene), to a lesser degree against E. faecalis and P. aeruginosa (MIC = 32 mg/L); (ii) were bacteriostatic (MBC >or= 256 mg/L); and (iii) MICs and MBCs obtained for clinical isolates were similar to those obtained with reference strains. Both compounds, the monomer and the calixarene, showed no apparent cytotoxicity, whereas hexamidine and synthalin A had significant toxic effects that increased with time and concentration and in a range of 100-1000 times that for calixarene. CONCLUSIONS: In conclusion, results confirm para-guanidinoethylcalix[4]arene as a broad-spectrum new agent or an auxiliary in antimicrobial chemotherapy.