Associated antimicrobial resistance in Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes

Pivmecillinam, the paradigm of an antibiotic with low resistance rates in Escherichia coli urine isolates despite high consumption

OBJECTIVES

Pivmecillinam, the oral version of mecillinam, represents one of the major recommended and used antibiotics for empiric and targeted treatment of urinary tract infections in primary care in Denmark, Norway and Sweden. Mecillinam resistant mutants in Escherichia coli develop easily in vitro, but their fitness cost has been shown to be high.

METHODS

We revisited the resistance and consumption data from the monitoring programmes in the three countries and compared pivmecillinam with ciprofloxacin from 2010 to 2020.

RESULTS

Mecillinam resistance rates in Escherichia coli remained around 6% in Denmark and Norway relative to a constant consumption in Norway of 1.6-1.8 DID (defined daily doses per 1000 inhabitants per day), and even increasing in Denmark from 1.6 to 2.3 DID. In Sweden resistance was significantly lower at 4% related to the lower consumption of 0.5 DID. For ciprofloxacin, resistance rates fluctuated around 6%-12%, highest in Sweden with the highest consumption (0.8-0.6 DID) and lowest in Denmark (0.55-0.35 DID) and Norway (0.7-0.3 DID), although consumption declined significantly in all three countries.

CONCLUSIONS

Pivmecillinam is an example of an antibiotic, which easily develops resistance in vitro, but apparently can be used broadly in primary care without increase in resistance rates.

Prismatic Silver Nanoparticles Decorated on Graphene Oxide Sheets for Superior Antibacterial Activity

Spherical silver nanoparticles (Ag NPs) and silver nanoprisms (Ag NPrsms) were synthesized and decorated on graphene oxide (GO) nanosheets. The Ag contents were 29% and 23% in the GO−Ag NPs and GO−Ag NPrsms, respectively. The Ag NPrsms exhibited stronger (111) crystal signal than Ag NPs. The GO−Ag NPrsms exhibited higher Ag (I) content (75.6%) than GO-Ag NPs (69.9%). Increasing the nanomaterial concentration from 25 to 100 µg mL−1 improved the bactericidal efficiency, and the antibacterial potency was in the order: GO−Ag NPrsms > GO−Ag NPs > Ag NPrsms > Ag NPs > GO. Gram-positive Staphylococcus aureus (S. aureus) was more vulnerable than Gram-negative Escherichia coli (E. coli) upon exposure to these nanomaterials. The GO−Ag NPrsms demonstrated a complete (100%) bactericidal effect against S. aureus at a concentration of 100 µg mL−1. The GO−Ag composites outperformed those of Ag or GO due to the synergistic effect of bacteriostatic Ag particles and GO affinity toward bacteria. The levels of reactive oxygen species produced in the bacteria−nanomaterial mixtures were highly correlated to the antibacterial efficacy values. The GO−Ag NPrsms are promising as bactericidal agents to suppress biofilm formation and inhibit bacterial infection.

Synergistic Effect of Co-Delivering Ciprofloxacin and Tetracycline Hydrochloride for Promoted Wound Healing by Utilizing Coaxial PCL/Gelatin Nanofiber Membrane

Combining multiple drugs or biologically active substances for wound healing could not only resist the formation of multidrug resistant pathogens, but also achieve better therapeutic effects. Herein, the hydrophobic fluoroquinolone antibiotic ciprofloxacin (CIP) and the hydrophilic broad-spectrum antibiotic tetracycline hydrochloride (TH) were introduced into the coaxial polycaprolactone/gelatin (PCL/GEL) nanofiber mat with CIP loaded into the PCL (core layer) and TH loaded into the GEL (shell layer), developing antibacterial wound dressing with the co-delivering of the two antibiotics (PCL-CIP/GEL-TH). The nanostructure, physical properties, drug release, antibacterial property, and in vitro cytotoxicity were investigated accordingly. The results revealed that the CIP shows a long-lasting release of five days, reaching the releasing rate of 80.71%, while the cumulative drug release of TH reached 83.51% with a rapid release behavior of 12 h. The in vitro antibacterial activity demonstrated that the coaxial nanofiber mesh possesses strong antibacterial activity against E. coli and S. aureus. In addition, the coaxial mats showed superior biocompatibility toward human skin fibroblast cells (hSFCs). This study indicates that the developed PCL-CIP/GEL-TH nanofiber membranes hold enormous potential as wound dressing materials.

The need to improve antimicrobial susceptibility testing capacity in Ugandan health facilities: insights from a surveillance primer

BACKGROUND

Lab-based surveillance (LBS) of antimicrobial resistance (AMR) is not systematically implemented in Uganda. We aimed to identify the gaps in establishing regular LBS of AMR in Uganda.

METHODS

This was a retrospective records review. It was done at Mulago Hospital (MH) Microbiology Lab (MHL). It analyzed lab records on bacteria and their antimicrobial susceptibility profiles (ASPs) over 6 months. Since MH is the national referral hospital, we hypothesized that (1) MHL is the best resourced and that any limitations seen here are amplified in labs at regional referral hospitals (RRHs) and health centers (HCs); (2) data from MHL on LBS mirrors that from labs at RRHs and HCs; (3) the state of records from MHL show lab performance and the presence or absence of standard operating procedures (SOPs), as would be the case at RRHs and HCs.

RESULTS

The lab got 1760 samples over the six months. The most common sample was urine (659, 37.4%). From the 1760 samples, data on 478 bacterial isolates were available. Urine gave the most isolates (159, 33.3%). Most of the isolates were gram-negative (267, 55.9%). Escherichia coli (100, 37%) was the most common gram-negative (of the Enterobacteriaceae). Pseudomonas aeruginosa (17, 6%) was the most common gram-negative (of the non-Enterobacteriaceae). The gram-negative bacteria were highly resistant to β-lactams. These were highly sensitive to carbapenems. The Staphylococcus aureus were highly resistant to β-lactams. The gram-positive bacteria were highly sensitive to vancomycin. ASPs for all bacterial categories were incomplete.

CONCLUSIONS

The findings from MHL suggest that there is a need to improve antimicrobial susceptibility testing capacity. They also suggest that the situation at RRHs and HCs around the country could be worse. So, there is a need to extend the political will, which already exists, into operational and implementation action.

A Biological Study of Anisotropic Silver Nanoparticles and Their Antimicrobial Application for Topical Use

The excessive use of antibiotics in both human and veterinary medicine has contributed to the development and rapid spread of drug resistance in bacteria. Silver nanoparticles (AgNPs) have become a tool of choice that can be used to treat these resistant bacteria. Several studies have shown that AgNPs have antibacterial and wound healing properties. In this study, we evaluated the biological activity of anisotropic AgNPs to develop an antimicrobial gel formulation for treating wound infections. We showed that some anisotropic AgNPs (S2) have an effective antibacterial activity against bacterial pathogens and low cytotoxicity to keratinocytes and fibroblasts in vitro. The MIC and MBC values were in the range of 2-32 µg/mL, and cytotoxicity had IC₅₀ values of 68.20 ± 9.71 µg/mL and 68.65 ± 10.97 µg/mL against human keratinocyte and normal human dermal fibroblast cells, respectively. The anisotropic AgNPs (S2) were used as a gel component and tested for antibacterial activity, including long-term protection, compared with povidone iodine, a common antiseptic agent. The results show that the anisotropic AgNPs can inhibit the growth of most tested bacterial pathogens and provide protection longer than 48 h, whereas povidone iodine only inhibits the growth of some bacteria. This study suggests that anisotropic AgNPs could be used as an alternative antimicrobial agent for treating bacterial skin infection and as a wound healing formulation.

Analysis of Multidrug Resistance in Staphylococcus aureus with a Machine Learning-Generated Antibiogram

Multidrug resistance (MDR) surveillance consists of reporting MDR prevalence and MDR phenotypes. Detailed knowledge of the specific associations underlying MDR patterns can allow antimicrobial stewardship programs to accurately identify clinically relevant resistance patterns. We applied machine learning and graphical networks to quantify and visualize associations between resistance traits in a set of 1,091 Staphylococcus aureus isolates collected from one New York hospital between 2008 and 2018. Antimicrobial susceptibility testing was performed using reference broth microdilution. The isolates were analyzed by year, methicillin susceptibility, and infection site. Association mining was used to identify resistance patterns that consisted of two or more individual antimicrobial resistance (AMR) traits and quantify the association among the individual resistance traits in each pattern. The resistance patterns captured the majority of the most common MDR phenotypes and reflected previously identified pairwise relationships between AMR traits in S. aureus Associations between β-lactams and other antimicrobial classes (macrolides, lincosamides, and fluoroquinolones) were common, although the strength of the association among these antimicrobial classes varied by infection site and by methicillin susceptibility. Association mining identified associations between clinically important AMR traits, which could be further investigated for evidence of resistance coselection. For example, in skin and skin structure infections, clindamycin and tetracycline resistance occurred together 1.5 times more often than would be expected if they were independent from one another. Association mining efficiently discovered and quantified associations among resistance traits, allowing these associations to be compared between relevant subsets of isolates to identify and track clinically relevant MDR.

Synergistic Antibacterial Activity of Silver-Loaded Graphene Oxide towards Staphylococcus Aureus and Escherichia Coli

In this study, the physicochemical and surface properties of the GO-Ag composite promote a synergistic antibacterial effect towards both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. Aureus) bacteria. GO-Ag NPs have a better bactericidal effect on E. coli (73%) and S. Aureus (98.5%) than pristine samples (pure Ag or GO). Transmission electron microscopy (TEM) confirms that the GO layers folded entire bacteria by attaching to the membrane through functional groups, while the Ag NPs penetrated the inner cell, thus damaging the cell membrane and leading to cell death. Cyclic voltammetry (CV) tests showed significant redox activity in GO-Ag NPs, enabling good catalytic performance towards H2O2 reduction. Strong reactive oxygen species (ROS) in GO-Ag NPs suggests that ROS might be associated with bactericidal activity. Therefore, the synergy between the physicochemical effect and ROS production of this material is proposed as the mechanism of its antibacterial activity.

Selective Inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis with Pulsed Electric Fields and Antibiotics

Objective: Increasing numbers of multidrug-resistant bacteria make many antibiotics ineffective; therefore, new approaches to combat microbial infections are needed. In addition, antibiotics are not selective-they kill pathogenic organisms as well as organisms that could positively contribute to wound healing (bio flora). Approach: Here we report on selective inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis, potential pathogens involved in wound infections with pulsed electric fields (PEFs) and antibiotics (mix of penicillin, streptomycin, and nystatin). Results: Using a Taguchi experimental design in vitro, we found that, under similar electric field strengths, the pulse duration is the most important parameter for P. aeruginosa inactivation, followed by the number of pulses and pulse frequency. P. aeruginosa, a potential severe pathogen, is more sensitive than the less pathogenic S. epidermidis to PEF (alone or in combination with antibiotics). Applying 200 pulses with a duration of 60 μs at 2.8 Hz, the minimum electric fields of 308.8 ± 28.3 and 378.4 ± 12.9 V/mm were required to inactive P. aeruginosa and S. epidermidis, respectively. Addition of antibiotics reduced the threshold for minimum electric fields required to inactivate the bacteria. Innovation: This study provides essential information, such as critical electric field parameters for bacteria inactivation, required for developing in vivo treatment and clinical protocols for using PEF for wound healing. Conclusion: A combination of PEFs with antibiotics reduces the electric field threshold required for bacteria disinfection. Such an approach simplifies devices required to disinfect large areas of infected wounds.

Trattamento antibiotico empirico, mirato o ragionato? Dalla pratica clinica alle Linee Guida EAU 2017

Empirical antibiotic treatment of urinary tract infections: from everyday clinical practice to EAU guidelines 2017

Recent epidemiological data confirm the increasing problem of antimicrobial resistance not only for hospitalized, healthcare-associated patients but also for outpatients. In particular, the progressive increase in resistance to broad-spectrum antibiotics, such as third-generation cephalosporins, fluoroquinolones, or carbapenems in Enterobacteriaceae, is an alarming situation for all urologists and general practitioners. The management of uncomplicated urinary tract infections are an important step in antibiotic stewardship achievement: a new approach is urgently required. All international Guidelines on urological infections suggest to take into account the following parameters for choosing antimicrobial therapy: spectrum and susceptibility patterns of the aetiological pathogens; efficacy for the particular indication in clinical studies; tolerability and adverse reactions; adverse ecological effects; costs and availability. In other words, an accurate evaluation of all patients and bacteria-related factors should be performed, along with the consideration of local data of bacterial resistance rate. According to these principles and the available susceptibility patterns in Italy, fosfomycin trometamol 3 g single dose and nitrofurantoin, are considered as drugs of first choice.

Broad-Spectrum Antibacterial Activity of Proteolytically Stable Self-Assembled αγ-Hybrid Peptide Gels

Bacterial infections pose a serious threat to mankind, and there is immense interest in the design and development of self-assembled peptide gels using ultrashort peptides for antibacterial applications. The peptide gels containing natural amino acids suffer from poor stability against proteolytic enzymes. Therefore, there is a need to design and develop peptide gels with improved stability against proteolytic enzymes. In the present work, we report the synthesis and characterization of α/γ hybrid peptides Boc-D-Phe-γ⁴-L-Phe-PEA (NH007) and Boc-L-Phe-γ⁴-L-Phe-PEA (NH009) to improve the proteolytic stability. Both of the dipeptides were found to self-assemble into gels in aqueous DMSO (3-5% w/v), and the self-assembly process was studied using FTIR and CD, which indicated antiparallel β-sheet formation with random coils in NH007 gels and random or unordered conformation in NH009. The rheological studies indicated viscoelastic characteristics for both gels; the storage modulus ( G') for NH007 and NH009 gels (3% w/v) was estimated as 0.2 and 0.5 MPa, higher than the loss modulus ( G''). Also, both gels demonstrated self-healing characteristics for six consecutive cycles when subjected to varying strains of 0.1 and 30% (200 s each). The peptide gels were incubated with a mocktail of proteolytic enzymes, proteinase K, pepsin, and chymotrypsin, and stability was monitored using RP HPLC. Up to 23 and 40% degradation was observed for NH007 (3%, w/v) in 24 and 36 h, and 77 and 94% degradation was observed for NH009 (3%, w/v), within the same period. Thus α/γ hybrid peptide gels containing D-Phe exhibited higher stability than gels fabricated using L-Phe. The use of D-residue in α/γ hybrid peptide significantly enhanced the stability of peptides against proteolytic enzymes, as the stability data reported in this work are possibly the best in class. Both peptide gels exhibited broad-spectrum antibacterial activity against Gram-negative and Gram-positive bacteria, such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The Pseudomonas aeruginosa and Staphylococcus aureus, in particular, are known to develop resistance. The NH007 (3%, w/v) demonstrated 65% inhibition, whereas NH009 (3%, w/v) showed 78% inhibition, with potent activity against Pseudomonas aeruginosa. Mechanistic studies, using SEM, HR-TEM, and bacterial live-dead assay, indicated entrapment of bacteria in gel networks, followed by interaction with cell membrane components and lysis. Cell viability (MTT assay) and toxicity (LDH assay) studies showed that both gels are not toxic to NIH 3T3 mouse embryonic fibroblast cells (mammalian). MTT assay showed >85% cell viability, and LDH assay exhibited not more than 15% cytotoxicity, even at higher concentrations (5%, w/v) and prolonged exposures (48 h). Overall, studies indicate the potential application of gels developed from the α/γ hybrid peptides in preventing biomaterial-related infections.

Antibiotic Resistance and Virulence Phenotypes of Recent Bacterial Strains Isolated from Urinary Tract Infections in Elderly Patients with Prostatic Disease

Acute bacterial prostatitis is one of the frequent complications of urinary tract infection (UTI). From the approximately 10% of men having prostatitis, 7% experience a bacterial prostatitis. The purpose of this study was to investigate the prevalence of uropathogens associated with UTIs in older patients with benign prostatic hyperplasia and to assess their susceptibility to commonly prescribed antibiotics as well as the relationships between microbial virulence and resistance features. Uropathogenic Escherichia coli was found to be the most frequent bacterial strain isolated from patients with benign prostatic hyperplasia, followed by Enterococcus spp., Enterobacter spp., Klebsiella spp., Proteus spp., Pseudomonas aeruginosa, and Serratia marcescens. Increased resistance rates to tetracyclines, quinolones, and sulfonamides were registered. Besides their resistance profiles, the uropathogenic isolates produced various virulence factors with possible implications in the pathogenesis process. The great majority of the uropathogenic isolates revealed a high capacity to adhere to HEp-2 cell monolayer in vitro, mostly exhibiting a localized adherence pattern. Differences in the repertoire of soluble virulence factors that can affect bacterial growth and persistence within the urinary tract were detected. The Gram-negative strains produced pore-forming toxins-such as hemolysins, lecithinases, and lipases-proteases, siderophore-like molecules resulted from the esculin hydrolysis and amylases, while Enterococcus sp. strains were positive only for caseinase and esculin hydrolase. Our study demonstrates that necessity of investigating the etiology and local resistance patterns of uropathogenic organisms, which is crucial for determining appropriate empirical antibiotic treatment in elderly patients with UTI, while establishing correlations between resistance and virulence profiles could provide valuable input about the clinical evolution and recurrence rates of UTI.

Surveillance of Gram-negative bacteria: impact of variation in current European laboratory reporting practice on apparent multidrug resistance prevalence in paediatric bloodstream isolates

This study evaluates whether estimated multidrug resistance (MDR) levels are dependent on the design of the surveillance system when using routine microbiological data. We used antimicrobial resistance data from the Antibiotic Resistance and Prescribing in European Children (ARPEC) project. The MDR status of bloodstream isolates of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa was defined using European Centre for Disease Prevention and Control (ECDC)-endorsed standardised algorithms (non-susceptible to at least one agent in three or more antibiotic classes). Assessment of MDR status was based on specified combinations of antibiotic classes reportable as part of routine surveillance activities. The agreement between MDR status and resistance to specific pathogen-antibiotic class combinations (PACCs) was assessed. Based on all available antibiotic susceptibility testing, the proportion of MDR isolates was 31% for E. coli, 30% for K. pneumoniae and 28% for P. aeruginosa isolates. These proportions fell to 9, 14 and 25%, respectively, when based only on classes collected by current ECDC surveillance methods. Resistance percentages for specific PACCs were lower compared with MDR percentages, except for P. aeruginosa. Accordingly, MDR detection based on these had low sensitivity for E. coli (2-41%) and K. pneumoniae (21-85%). Estimates of MDR percentages for Gram-negative bacteria are strongly influenced by the antibiotic classes reported. When a complete set of results requested by the algorithm is not available, inclusion of classes frequently tested as part of routine clinical care greatly improves the detection of MDR. Resistance to individual PACCs should not be considered reflective of MDR percentages in Enterobacteriaceae.

Immune Modulation as an Effective Adjunct Post-exposure Therapeutic for B. pseudomallei

Melioidosis is caused by the facultative intracellular bacterium Burkholderia pseudomallei and is potentially fatal. Despite a growing global burden and high fatality rate, little is known about the disease. Recent studies demonstrate that cyclooxygenase-2 (COX-2) inhibition is an effective post-exposure therapeutic for pulmonary melioidosis, which works by inhibiting the production of prostaglandin E2 (PGE2). This treatment, while effective, was conducted using an experimental COX-2 inhibitor that is not approved for human or animal use. Therefore, an alternative COX-2 inhibitor needs to be identified for further studies. Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug (NSAID) COX-2 inhibitor marketed outside of the United States for the treatment of migraines. While this drug was developed for COX-2 inhibition, it has been found to modulate other aspects of inflammation as well. In this study, we used RAW 264.7 cells infected with B pseudomallei to analyze the effect of TA on cell survival, PGE2 production and regulation of COX-2 and nuclear factor- kappaB (NF-ĸB) protein expression. To evaluate the effectiveness of post-exposure treatment with TA, results were compared to Ceftazidime (CZ) treatments alone and the co-treatment of TA with a sub-therapeutic treatment of CZ determined in a study of BALB/c mice. Results revealed an increase in cell viability in vitro with TA and were able to reduce both COX-2 expression and PGE2 production while also decreasing NF-ĸB activation during infection. Co-treatment of orally administered TA and a sub-therapeutic treatment of CZ significantly increased survival outcome and cleared the bacterial load within organ tissue. Additionally, we demonstrated that post-exposure TA treatment with sub-therapeutic CZ is effective to treat melioidosis in BALB/c mice.

Urological infections due to multidrug-resistant bacteria: what we need to know?

PURPOSE

Recent epidemiological data have confirmed the increasing problem of antimicrobial resistance not only for hospitalized, healthcare-associated patients, but also for outpatients. In particular, the progressive increase in resistance to broad-spectrum antibiotics, such as third-generation cephalosporins, fluoroquinolones or carbapenems in Enterobacteriaceae, is an alarming situation for all urologists and general practitioners. Here, we aimed to review the epidemiological data of multidrug-resistant bacteria in the urological setting, in order to summarize all diagnostic and therapeutic recommendations to use in everyday clinical practice.

METHODS

We collected all recent publications from Medline and Cochrane Library from January 2000 to December 2013. Moreover, data from the abstracts presented at the EAU and AUA Congresses during the last 5 years have also been analyzed. All papers were evaluated by an expert panel on urological infections on behalf of the Italian Urological Association (SIU).

RESULTS

Fluoroquinolone and other antibiotic-resistant bacteria prevalence is normally very high in the lower urinary tract infection patients. In particular, multidrug-resistant bacteria prevalence in urological practice contributes to infectious morbidity increasing the financial costs to healthcare system. The expert panel on urological infections on behalf of the Italian Urological Association formulated new diagnostic pathway and therapeutic protocol in patients affected by urological tract infections due to multidrug-resistant bacteria.

CONCLUSIONS

The recent emergence of multidrug-resistant pathogens is an alarming public health issue also in urological practice with socioeconomic importance. Our practice should be revised on the basis of these new acquisitions.

Resistance Genes and Genetic Elements Associated with Antibiotic Resistance in Clinical and Commensal Isolates of Streptococcus salivarius

The diversity of clinical (n = 92) and oral and digestive commensal (n = 120) isolates of Streptococcus salivarius was analyzed by multilocus sequence typing (MLST). No clustering of clinical or commensal strains can be observed in the phylogenetic tree. Selected strains (92 clinical and 46 commensal strains) were then examined for their susceptibilities to tetracyclines, macrolides, lincosamides, aminoglycosides, and phenicol antibiotics. The presence of resistance genes tet(M), tet(O), erm(A), erm(B), mef(A/E), and catQ and associated genetic elements was investigated by PCR, as was the genetic linkage of resistance genes. High rates of erythromycin and tetracycline resistance were observed among the strains. Clinical strains displayed either the erm(B) (macrolide-lincosamide-streptogramin B [MLSB] phenotype) or mef(A/E) (M phenotype) resistance determinant, whereas almost all the commensal strains harbored the mef(A/E) resistance gene, carried by a macrolide efflux genetic assembly (MEGA) element. A genetic linkage between a macrolide resistance gene and genes of Tn916 was detected in 23 clinical strains and 5 commensal strains, with a predominance of Tn3872 elements (n = 13), followed by Tn6002 (n = 11) and Tn2009 (n = 4) elements. Four strains harboring a mef(A/E) gene were also resistant to chloramphenicol and carried a catQ gene. Sequencing of the genome of one of these strains revealed that these genes colocalized on an IQ-like element, as already described for other viridans group streptococci. ICESt3-related elements were also detected in half of the isolates. This work highlights the potential role of S. salivarius in the spread of antibiotic resistance genes both in the oral sphere and in the gut.

Characterization of ambrette seed oil and its mode of action in bacteria

In the present study, chemical composition and the antibacterial mechanism of ambrette seed oil are investigated. Chemical composition of the oil was analysed by gas chromatography-mass spectrometry (GC-MS). Thirty-five compounds were identified and the major compounds were found to be farnesol acetate (51.45%) and ambrettolide (12.96%). The antibacterial activity was performed by well diffusion assay and the mechanisms were studied by measuring the alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and protein leakage assays. The antibacterial effect of the ambrette seed oil showed inhibitory effect against Bacillus subtilis, Staphylococcus aureus and Enterococcus faecalis. The LDH activity was high in all tested bacteria compared with control, whereas the ALP and protein concentrations were also increased in E. faecalis. Molecular docking revealed the ligands farnesol acetate and ambrettolide had satisfactory binding energy towards the beta lactamase TEM-72 and dihydrofolate reductase (DHFR) protein. Due to its better antibacterial properties, the ambrette seed oil could be used as a source of antibacterial agents.

The production of ginsenosides in hairy root cultures of American Ginseng, Panax quinquefolium L. and their antimicrobial activity

Panax quinquefolium, American ginseng, is valued for its triterpene saponins, known as ginsenosides. These constituents possess a number of pharmacological properties and hairy root cultures can synthesize similar saponins to those of field-cultivated roots. The antibacterial activity of extracts from three hairy root clones of P. quinquefolium L. was tested against a range of standard bacterial and yeast strains. The agar diffusion method was used to evaluate inhibition of microbial growth at various extract concentrations. Commercial antibiotics were used as positive reference standards to determine the sensitivity of the strains. Susceptibility testing to antibiotics was also tested using the disk diffusion method. The minimal inhibitory concentration values of the extracts, obtained by agar diffusion, ranged from 0.8 to 1.4 mg/ml. The results showed that extracts from hairy root cultures inhibited the growth of bacteria and yeast strains and suggest that they may be useful in the treatment of infections caused by pathogenic microorganisms.

IDSA Clinical Practice Guideline for Acute Bacterial Rhinosinusitis in Children and Adults

Evidence-based guidelines for the diagnosis and initial management of suspected acute bacterial rhinosinusitis in adults and children were prepared by a multidisciplinary expert panel of the Infectious Diseases Society of America comprising clinicians and investigators representing internal medicine, pediatrics, emergency medicine, otolaryngology, public health, epidemiology, and adult and pediatric infectious disease specialties. Recommendations for diagnosis, laboratory investigation, and empiric antimicrobial and adjunctive therapy were developed.

The antimicrobial activity of thyme essential oil against multidrug resistant clinical bacterial strains

AIM

The aim of this work was to investigate the antimicrobial activity of thyme essential oil against clinical multidrug resistant strains of Staphylococcus, Enterococcus, Escherichia, and Pseudomonas genus.

MATERIALS

The antibacterial activity of oil was tested against standard strains of bacteria and 120 clinical strains isolated from patients with infections of the oral cavity, abdominal cavity, respiratory and genitourinary tracts, skin, and from the hospital environment.

METHODS

Agar diffusion was used to determine the microbial growth inhibition of bacterial growth at various concentrations of oil from Thymus vulgaris. Susceptibility testing to antibiotics was carried out using disk diffusion.

RESULTS

Thyme essential oil strongly inhibited the growth of the clinical strains of bacteria tested.

CONCLUSIONS

The use of phytopharmaceuticals based on an investigated essential oil from thyme in the prevention and treatment of various human infections may be reasonable.

Antimicrobial activity against Streptococcus pneumoniae and Haemophilus influenzae collected globally between 2004 and 2008 as part of the Tigecycline Evaluation and Surveillance Trial

We report here on the in vitro activity of tigecycline and comparators against a global collection of Streptococcus pneumoniae and Haemophilus influenzae collected between 2004 and 2008 as part of the Tigecycline Evaluation and Surveillance Trial. A total of 6785 S. pneumoniae and 6642 H. influenzae isolates were collected, most from North America. The percentages of penicillin-intermediate resistance and penicillin resistance among S. pneumoniae in North America were 27.8% and 14.3%, respectively. Penicillin resistance ranged from 9.3% in Europe to 25.1% in the Asia-Pacific Rim. The rate of beta-lactamase-producing H. influenzae was 25.8% in North America, and among the other regions, it ranged from 8.7% in South Africa to 26.8% in the Asia-Pacific Rim. Tigecycline MIC(90)'s were 0.03 to 0.12 mg/L and 0.5 to 2 mg/L, depending on the region considered, against S. pneumoniae and H. influenzae, respectively. Tigecycline had low MIC(90)'s against S. pneumoniae and H. influenzae, irrespective of resistance to beta-lactams.

Little evidence for reversibility of trimethoprim resistance after a drastic reduction in trimethoprim use

OBJECTIVES

The worldwide rapid increase in antibiotic-resistant bacteria has made efforts to prolong the lifespan of existing antibiotics very important. Antibiotic resistance often confers a fitness cost in the bacterium. Resistance may thus be reversible if antibiotic use is discontinued or reduced. To examine this concept, we performed a 24 month voluntary restriction on the use of trimethoprim-containing drugs in Kronoberg County, Sweden.

METHODS

The intervention was performed on a 14 year baseline of monthly data on trimethoprim resistance and consumption. A three-parameter mathematical model was used to analyse the intervention effect. The prerequisites for reversion of resistance (i.e. fitness cost, associated resistance and clonal composition) were studied on subsets of consecutively collected Escherichia coli from urinary tract infections.

RESULTS

The use of trimethoprim-containing drugs decreased by 85% during the intervention. A marginal but statistically significant effect on the increase in trimethoprim resistance was registered. There was no change in the clonal composition of E. coli and there was no measurable fitness cost associated with trimethoprim resistance in clinical isolates. The frequency of associated antibiotic resistances in trimethoprim-resistant isolates was high.

CONCLUSIONS

A lack of detectable fitness cost of trimethoprim resistance in vitro together with a strong co-selection of other antibiotics could explain the rather disappointing effect of the intervention. The result emphasizes the low possibility of reverting antibiotic resistance once established and the urgent need for the development of new antibacterial agents.

Antibiotic susceptibility of thermo-tolerant Escherichia coli 2 isolated from drinking water of Khairpur City, Sindh, Pakistan

A total 72 drinking water sample were collected and analyzed by membrane filtration method during 1 year study from various points in Khairpur City. Out of these 58 (80.55%) samples were found to be contaminated with thermo-tolerant Escherichia coli 2. The susceptibility of these isolates to 35 antibiotics was studied by disc diffusion method and the organism was highly sensitive to levoflaxin, cefipime, enoxobid, noroxin, tarivid, ciproxin, avelox, amikacin, kanamycin, rocifin, pipenedic acid and slightly sensitive to cravit, naladixic acid, neomycin, cefizox, fortum cefotaxime, cefizox, fortum, tobramycin and cefoperoxone. The resistance against 16 antibiotics such as meropenem, linkomycin, fusidic acid, orbenin, penicillin, streptomycin, bacitracin, minocin, zinacef, amoxil, ceclor, claracid, cephalexin, augmentin, cephradin and dalacin was shown by these isolates. We report the presence of multi-drug resistance in thermo-tolerant Escherichia coli isolated in municipal water with different levels of prevalence in Khairpur City. In this study a higher number of positive results were obtained in all sampling points indicating the more fecally polluted municipal water.

Determinação da resistência antimicrobiana associada em isolados clínicos de Staphylococcus aureus e Pseudomonas aeruginosa em um hospital público de Goiânia, Estado de Goiás

Este estudo avaliou a resistência antimicrobiana associada de Pseudomonas aeruginosa e Staphylococcus aureus a um agente antimicrobiano com outras drogas. A resistência antimicrobiana associada foi calculada através do risco relativo. Houve uma relação óbvia entre resistência à oxacilina e a outros agentes antimicrobianos entre os isolados de Staphylococcus aureus resistentes à oxacilina (68,5%) superior a 32%, com exceção da linezolida (6,7%). Resistência associada pronunciada entre drogas foi observada para isolados de Pseudomonas aeruginosa, particularmente entre ciprofloxacina e os carbapenens (59,6% a 60,7%), entre aminoglicosídeos e carbapenens (66,3% a 67,7%) e os demais β-lactâmicos (52,3% a 85,8%). O presente trabalho enfatiza a importância da cultura diagnóstica e do teste de suscetibilidade na seleção de um correto agente antimicrobiano com relação ao impacto clínico no aumento da multirresistência e na seleção de resistência antimicrobiana associada.

'Pre-emptive culturing' will improve the chance of 'getting it right' when empirical therapy of urinary tract infections fails

Antibiotic resistance is increasing and beginning to affect the outcome of empirical antimicrobial therapy of urinary tract infections. Associated resistance, i.e. the fact that a bacterium resistant to one antibiotic is often much more likely to be resistant to other antibiotics, drastically decreases our chances of getting a second empirical attempt right. To increase the use of narrow-spectrum antibiotics, which are considered to be less selective for resistance, we need to develop new strategies from the laboratory to support our clinical colleagues. We suggest that 'pre-emptive culturing' of urine (i.e. a culture obtained before empirical treatment is instituted) will prevent clinicians from making a second improper empirical choice or having to resort to expensive broad-spectrum antimicrobials, which may drive resistance further. This strategy will be especially important in settings with high levels of resistance.

The epidemiology of antibiotic resistance

Antibiotic resistance has reached crisis point in many hospitals around the world. The majority are swamped with meticillin-resistant Staphylococcus aureus (MRSA), and many with multidrug-resistant (MDR) Gram-negatives. Whilst there are good treatment alternatives available for serious infections due to MRSA, mortality rates remain high. For MDR Gram-negatives the situation is more complex and worrying. There are few, if any, new agents in development that can be expected to benefit the situation in the next decade. Moreover, extreme (or extensive) drug-resistant and even pandrug-resistant Gram-negative infections are increasingly being described. Although definitions are confused in this area, reports suggest that patients in some intensive care units are dying from lack of availability of any antibiotic active against certain strains of Pseudomonas aeruginosa and Acinetobacter baumannii. A better understanding of the molecular basis of resistance is urgently needed if it is to be successfully overcome. Moreover, we urgently need better global early warning systems to detect new resistances and put mechanisms in place for their control.