Antibacterial Resistance Rates Research Articles

Efficacy and safety of intra-articular-only meropenem after one-stage revision for treating Escherichia coli-induced periprosthetic joint infection in a rat model.

The optimum type of antibiotics and their administration route for treating Gram-negative (GN) periprosthetic joint infection (PJI) remain controversial. This study aimed to determine the GN bacterial species and antibacterial resistance rates related to clinical GN-PJI, and to determine the efficacy and safety of intra-articular (IA) antibiotic injection after one-stage revision in a GN pathogen-induced PJI rat model of total knee arthroplasty. A total of 36 consecutive PJI patients who had been infected with GN bacteria between February 2015 and December 2021 were retrospectively recruited in order to analyze the GN bacterial species involvement and antibacterial resistance rates. Antibiotic susceptibility assays of the GN bacterial species were performed to screen for the most sensitive antibiotic, which was then used to treat the most common GN pathogen-induced PJI rat model. The rats were randomized either to a PJI control group or to three meropenem groups (intraperitoneal (IP), IA, and IP + IA groups). After two weeks of treatment, infection control level, the side effects, and the volume of antibiotic use were evaluated. Escherichia coli was the most common pathogen in GN-PJI, and meropenem was the most sensitive antibiotic. Serum inflammatory markers, weightbearing activity, and Rissing score were significantly improved by meropenem, especially in the IA and IP + IA groups ( p < 0.05). Meropenem in the IA group eradicated E. coli from soft-tissue, bone, and prosthetic surfaces, with the same effect as in the IP + IA group. Radiological results revealed that IA and IP + IA meropenem were effective at relieving bone damage. Haematoxylin and eosin staining also showed that IA and IP + IA meropenem improved synovial inflammation and bone destruction. No pathological changes in the main organs or abnormal serum markers were observed in any of the meropenem-treated rats. The IA group required the lowest amount of meropenem, followed by the IP and IP + IA groups. IA-only meropenem with a two-week treatment course was effective and safe for PJI control following one-stage revision in a rat model, with less meropenem use.

Boron Compound-Based Treatments Against Multidrug-Resistant Bacterial Infections in Lung Cancer In Vitro Model.

Multidrug-resistant bacteria is one of the most important public health problems. Increasing rates of antibacterial resistance also affect the outcomes of medical approaches. Cancer treatment because of immune system deficiency (chemotherapy or steroids usage) commonly can cause infection. Lung cancer is the dominant cause of cancer-related deaths, and infection is the most common cause of death among those patients. In this study, it was aimed to determine the antimicrobial, antibiofilm, and anticancer activity of boron compounds. A549 lung cancer cell line was infected with Acinetobacter baumannii (ATCC 19606), Klebsiella pneumoniae (ATCC 700603), and Pseudomonas aeruginosa (ATCC 27853). In order to determine the fractional inhibitory concentration (FIC) index, antibiotics and boron compound concentrations prepared according to the minimum inhibitory concentration (MIC) values were determined by the checkerboard method. In our study results, the antibiofilm activity was an average of 46% in A. baumannii+boron compounds, 45% in P. aeruginosa+boron compounds, and 43% in K. pneumoniae. Cell culture analysis results show a decrease in viability and antioxidant capacity and an increase in total oxidant status after adding boron compounds to the culture. Immunofluorescence results show a correlation with MTT, and boron compounds increased 8-OHdG expression in comparison to antibiotic administration. In conclusion, boron compounds have promising effects on bacteria, especially in resistant bacteria spp.

Systematic Literature Review of Real-world Evidence of Ceftolozane/Tazobactam for the Treatment of Respiratory Infections.

IntroductionGram-negative nosocomial pneumonia (NP), including hospital-acquired bacterial pneumonia (HABP), ventilated HABP (vHABP), and ventilator-associated bacterial pneumonia (VABP), is a significant cause of morbidity and mortality. Common pathogens, including Enterobacterales and Pseudomonas aeruginosa, are prevalent in healthcare settings and have few effective treatment options due to high rates of antibacterial resistance. Resistant pathogens are associated with significantly worse outcomes, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials of patients with NP. This review aims to collate data on C/T use for HABP/vHABP/VABP infections in real-world clinical practice.MethodsThis systematic literature review searched online biomedical databases for real-world studies of C/T used to treat Gram-negative respiratory tract infections (RTIs) between January 2009 and June 2020.ResultsThirty-three studies comprising 658 patients were identified. Pneumonia was the most common infection treated with C/T (85%), with a smaller number of unspecified RTIs (9%) and tracheobronchitis (5%) reported. The majority of patients had respiratory infections caused by P. aeruginosa (92.8%), of which 88.1% were multidrug-resistant. Examination of these studies demonstrated an increase in the percentage of patients receiving the recommended dose of C/T for respiratory infections (3 g q8h or renal impairment-adjusted) over time (36.8% of patients in 2017 to 71.5% in 2020). Clinical success rates ranged from 51.4 to 100%, with 10 studies (55.6% of studies reporting clinical success) reporting clinical success rates of > 70%; microbiological success rates ranged from 57.0 to 100.0%, with three studies (60.0% of studies reporting microbiological success) reporting microbiological success rates of > 70%. Thirty-day mortality ranged from 0.0 to 33.0%, with nine studies (90% of studies reporting mortality) reporting 30-day mortality of < 30%.ConclusionsThe studies identified in this review demonstrate that C/T shows similar outcomes as those seen in clinical trials, despite the higher frequency of multidrug-resistant pathogens, and comorbidities that may have been excluded from the trials.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40121-021-00491-x.

Designing Development Programs for Non-Traditional Antibacterial Agents

In the face of rising rates of antibacterial resistance, many responses are being pursued in parallel, including ‘non-traditional’ antibacterial agents (agents that are not small-molecule drugs and/or do not act by directly targeting bacterial components necessary for bacterial growth). In this Perspective, we argue that the distinction between traditional and nontraditional agents has only limited relevance for regulatory purposes. Rather, most agents in both categories can and should be developed using standard measures of clinical efficacy demonstrated with non-inferiority or superiority trial designs according to existing regulatory frameworks. There may, however, be products with non-traditional goals focused on population-level benefits that would benefit from extension of current paradigms. Discussion of such potential paradigms should be undertaken by the development community.

Characterization of the Ear Canal Bacterial Flora Present in Hearing Aids (HA) Wearing Subjects

The use of hearing aids (HA) is considered a predisposing factor for ear microbial infections. We undertook this study to compare the presence and nature of the microbial flora inhabiting of ears of HA and non-HA (nHA) users. Swab samples of the ears of HA and nHA users were collected from the Institute of Otolaryngology, “Cattolica del Sacro Cuore” University “Agostino Gemelli”, Rome, Italy. Swab samples were taken from the ear canal of 57 HA and 33 nHA users. The components of the microbial flora present on each swab sample were identified and characterized at the level of species. A total of 41 different bacterial species were identified. A statistically significant prevalence of polymicrobial communities was found in ears presenting signs of inflammation (2.5 ± 1.7 vs 2.1 ± 1.3; P = 0.02) and in HA users (2.3 ± 1.2 vs 1.7 ± 1.0; P = 0.002). Few putative pathogens were detected. Candida albicans spp. was not isolated in our study. A small number of swab samples presented no microbial growth. Bacterial species isolated from HA users with and without inflammation were assayed for the ability to form biofilm. Among gram-positive and gram-negative bacteria, S. aureus, CoNS, P. aeruginosa and K. pneumoniae were found to be strong biofilm producers. S. aureus and P. aeruginosa, isolated only from the ears of HA and nHA users presenting signs of inflammation, were further analyzed for their antibiotic-resistance profile and characterized by the Multilocus Sequence Typing (MLST) assay. The highest rates of antibacterial resistance were in S. aureus to penicillin (75.5%) and in P. aeruginosa, to amoxicillin-clavulanic acid, cefotaxime, ertapenem, tigecycline and trime-thoprim-sulfamethoxazole (100%). Moreover, three S. aureus strains (37.5%) were methicillin-resistant (MRSA). Of the eight S. aureus isolates, we identified six sequence types (ST) indicating that 75% are likely independent clones. For what it concerned P. aeruginosa, six different STs were assigned. Interestingly, two out of the six strains presented newly identified ST values. This study sheds new light on the combined effect of the presence of HA devices and signs of external ear inflammation on the composition of the ear bacterial flora. Our results reinforce the need to practice careful hygiene of HA devices to prevent serious ear canal infections.

Evaluating the resistance pattern of gram-negative bacteria during three years at the nephrology ward of a referral hospital in southwest of Iran.

Background: Gram-negative bacteria are associated with an increase in rates of antibacterial resistance. In most low- and middle-income countries such as Iran, there is no continuous surveillance system for antibiotic resistance. Objective: The purpose of this survey was to determine the pattern of antimicrobial sensitivity of gram-negative bacteria within 3 consecutive years at a nephrology ward of Nemazee hospital in Shiraz. Materials and Methods: During a 3-year period from 2013 to 2015 at the adult nephrology ward, bacteriological data of all biological samples of hospitalized patients in favor of gram-negative microorganisms were analyzed retrospectively. Antimicrobial susceptibility was performed by the Kirby-Bauer disc diffusion method. Results: The most common gram negative bacterium isolated from biological samples was Escherichia coli (43.9%). The highest (86.3%-94.1%) antibacterial resistance rate was associated with Acinetobacter spp. The most frequent resistance was seen with cephalosporins. In contrast to ceftriaxone, ciprofloxacin, and trimethoprim/sulfamethoxazole, nitrofurantoin and aminoglycosides remained their acceptable activity against E. coli. At least three-fourths (75%) of Acinetobacter spp. isolates was resistant to either aminoglycosides or imipenem. All (100%) isolated Acinetobacter spp. and Pseudomonas aeruginosa species were susceptible to colistin. The rate of Acinetobacter spp. and P. aeruginosa resistant to three or more drugs was 81.7% and 74.6%, respectively. Conclusions: The resistant rate of gram negative pathogens to different tested antibacterial agents was considerably high and has increased during the recent three years in our center.

Marine Bivalve Mollusks As Possible Indicators of Multidrug-Resistant Escherichia coli and Other Species of the Enterobacteriaceae Family

The mechanisms for the development and spread of antibacterial resistance (ABR) in bacteria residing in environmental compartments, including the marine environment, are far from understood. The objective of this study was to examine the ABR rates in Escherichia coli and other Enterobacteriaceae isolates obtained from marine bivalve mollusks collected along the Norwegian coast during a period from October 2014 to November 2015. A total of 549 bivalve samples were examined by a five times three tube most probable number method for enumeration of E. coli in bivalves resulting in 199 isolates from the positive samples. These isolates were identified by biochemical reactions and matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry, showing that 90% were E. coli, while the remaining were species within the genera Klebsiella, Citrobacter, and Enterobacter. All 199 isolates recovered were susceptibility tested following the European Committee on Antimicrobial Susceptibility Testing disk diffusion method. In total, 75 of 199 (38%) isolates showed resistance to at least one antibacterial agent, while multidrug-resistance were seen in 9 (5%) isolates. One isolate conferred resistance toward 15 antibacterial agents. Among the 75 resistant isolates, resistance toward extended-spectrum penicillins (83%), aminoglycosides (16%), trimethoprim (13%), sulfonamides (11%), tetracyclines (8%), third-generation cephalosporins (7%), amphenicols (5%), nitrofurans (5%), and quinolones (5%), were observed. Whole-genome sequencing on a selection of 10 E. coli isolates identified the genes responsible for resistance, including blaCTX-M genes. To indicate the potential for horizontal gene transfer, conjugation experiments were performed on the same selected isolates. Conjugative transfer of resistance was observed for six of the 10 E. coli isolates. In order to compare E. coli isolates from bivalves with clinical strains, multiple-locus variable number tandem repeats analysis (MLVA) was applied on a selection of 30 resistant E. coli isolates. The MLVA-profiles were associated with community-acquired E. coli strains causing bacteremia. Our study indicates that bivalves represent an important tool for monitoring antibacterial resistant E. coli and other members of the Enterobacteriaceae family in the coastal environment.

Factors affecting antibacterial activity of acrylic resin containing silver nanoparticles

In this research, silver nanoparticles were dispersed into acrylic emulsion by high-speed stirring method using scattered disc at room temperature. Antibacterial activity of the mixture was examined through changes of some parameters such as nanosilver concentration, dispersing time and water addition amount. The antibacterial properties were evaluated via changes of number and size of colonies forming on the surface of the film casting from this mixture in petri dishes. Besides that, the silver nanoparticles distribution ability into the film was evaluated through the analysis of scanning electron microscope images. As results, the surfaces of the acrylic resin shown on the high antibacterial resistance rates reached about 97.89% for 1,500 ppm silver nanoparticles dispersing into acrylic emulsion in 3 hours with the water addition amounts about 5%.

Therapeutic effects of a combined antibiotic-enzyme treatment on subclinical mastitis in lactating dairy cows

The objective of this study was to evaluate a combined antibiotic-enzyme therapy for Staphylococcus aureus mastitis and biofilm formation. A total of 141 cases of S. aureus chronic mastitis from three farms were divided into two groups: the control group (n = 54) were treated with Nafpenzal® ointment; the enzyme + antibiotic group (n = 87) were treated with Nafpenzal® plus an enzymatic ointment (MastiVeyxym®). Quantitative determination of biofilm formation was determined using a colorimetric microplate assay and the detection of ica genes by PCR. Enzyme + antibiotic therapy did not significantly improve cure rates compared to control (48.3 vs 38.9%). The cure rate for infections caused by biofilm-positive strains was 42.6 and 46.6% for control and enzyme + antibiotic groups, respectively (P > 0.05). Comparison of cure rates between farms showed a relationship with somatic cell count (SCC), parity and oxacillin resistance. 79.4% of the isolates produced biofilm and antibacterial resistance rates for oxacillin, penicillin and streptomycin were 25.5, 71.6 and 95.7%, respectively. These results indicate that while the increase in mastitis cure rate using enzymatic therapy was not significant, this treatment could be useful in some situations.

Antifouling coatings utilizing highly effective hyaluronic acid-penicillin conjugates

Event Abstract Back to Event Antifouling coatings utilizing highly effective hyaluronic acid-penicillin conjugates Nisha Hollingsworth1 and Anita Shukla2 1 Brown University, Department of Molecular Pharmacology, Physiology, & Biotechnology, United States 2 Brown University, Center for Biomedical Engineering; School of Engineering, United States Introduction: Bacterial infections remain among the leading causes of death worldwide and are becoming increasingly difficult to treat due to rising rates of antibacterial resistance. There is a critical need for new, effective antibiotics that eradicate bacteria before resistance can develop. Antimicrobial polymers can be used to prevent and treat infection in a variety of applications, including antifouling coatings. Synthesis of most common antimicrobial polymers, such as quaternary ammonium polymers, involves harsh solvents to yield an often cytotoxic and marginally effective product[1]. Here, we describe the aqueous synthesis of a polymer-drug conjugate utilizing FDA-approved and naturally occurring hyaluronic acid (HA) and existing penicillin antibiotics. Our novel conjugates display superior antibacterial efficacy compared to non-conjugated penicillins, while also preventing the attachment of bacteria. Methods: Synthesis: Colloidal carbodiimide chemistry[2] was used to conjugate one of three penicillins (carbenicillin, penicillin G, and ampicillin) to HA (at three average molecular weights: 39, 150, and 1650 kDa) via an ester bond [Fig 1a]. Characterization: The structure, size, and percent conjugation of the products was determined using Fourier transform-infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). Antibacterial efficacy was determined using a broth microdilution assay versus Staphylococcus aureus and Streptococcus pyogenes as previously reported[3]. Bovine erythrocyte hemolysis was examined by measuring hemoglobin absorbance at 540 nm. Bacterial attachment characterization: The 1650 kDa conjugates were coated on 12 mm round cover glass at two surface concentrations (1.0 and 0.1 mg/mm2) and incubated with S. aureus for 1 hour, rinsed in PBS, and immediately plated onto blood agar along with controls. Results and Discussion: FTIR validated successful ester formation (strong ester C-O stretch at ~1050 cm-1) [Fig. 1b] and SEC confirmed efficient conjugation (≥ 90%) [Fig 1c]. The broth microdilution assays demonstrated that all of the conjugates are at least 10x more effective than the penicillin alone against S. aureus and S. pyogenes (based on the number of penicillin molecules present), with higher HA molecular weight leading to increased efficacy [Fig 1d,e]. Bacteria were unable to attach to the conjugate coated glass at a surface concentration of 1.0 mg/mm2 [Fig. 2]. Bacterial attachment is the first step of biofilm formation[4], motivating the coating as an antifoulant. Moreover, all conjugates were determined to be biocompatible, causing hemolysis at concentrations 102-104x their minimum inhibitory concentrations (MICs). Conclusion: A library of HA-penicillin conjugates was developed that exhibits antifouling behavior. Each conjugate was significantly more effective in eradicating bacteria than penicillin alone. By reducing the amount of penicillin necessary to effectively eradicate bacteria, drug exposure is reduced, helping to prevent the development of resistance. United States Office of Naval Research (ONR); School of Engineering, Brown University, Providence, RI USA

Analysis on the antibacterial resistance rates of pseudomonsa aeruginosa in hospital

Objective To investigate the changes of antibiotic resistance spectrum of pseudomonsa aeruginosa in hospital.Methods Pseudomonsa aeruginosa were isolated from clinical samples and their resistances to antibiotic in our hospital from Jan 2009 to DEC 2012,which were analyzed and studied retrospectively.Results A total of 1717 strains of pseudomonsa aeruginosa were isolated,there was an elevated tendency of the resistance rates to common antibacterials in pseudomonsa aeruginosa during the past four years.We found that the lowest average resistance rate was amikacin (32.0％); the rate of meropenem (36.2％),imipenem (39.4％) and piperacillin/tazobactam (39.7％) were less than 40％.So many antibacterials'drug resistance rate had changed remarkably.Conclusion Pseudomonsa aeruginosa had an elevated tendency on resistance rates,and the phenomenon of multi-drug resistance was serious.To prevent the pseudomonsa aeruginosa infection outbreak,rational use of clinical medicine is much more important. Key words: Pseudomonsa aeruginosa; Antibiotic; Drug resistance

Distribution of blaTEM, blaSHV and blaCTX-M Genes Among Escherichia coli Isolates Causing Urinary Tract Infection in Children

Background: Emerging antibacterial resistance rates and extended-spectrum-β-lactamase producing Escherichia coli recovered from urinary tract infections (UTI) is an increasing problem in different regions, limiting therapeutic options. Objectives: The aim of this study was the detection of blaTEM, blaSHV and blaCTX-M genes among Escherichia coli strains causing Urinary Tract Infection in children from Iran. Materials and Methods: A total of 100 Escherichia coli isolates were collected from urine specimens of patients with UTI who had referred to the Children Medical Center, Tehran, Iran between November 2012 and July 2013. Antibiotic susceptibility test was performed by Kirby-Bauer disc diffusion method according to CLSI guidelines. The blaCTX-M, blaTEM and blaSHV genes were detected by PCR and sequencing methods. Results: The resistance rate of isolates to cefotaxime, ceftazidime, imipenem, gentamicin, amikacin, cefepime, piperacillin/tazobactam, co-trimoxazole, nitrofurantoin, cefixime and cephalothin, were 51 (51%), 24 (24%), 0 (0%), 25 (25%), 2 (2%), 6 (6%), 2 (2%), 79 (79%), 7 (7%), 36 (36%) and 43 (43%), respectively. In this study, imipenem was more active than other antibiotics. The existence of blaTEM-1 and blaCTX-M-15 was detected in 69 (69%) and 74 (74%) isolates respectively, while blaSHV gene was not detected. Conclusions: The prevalence of β-lactamase-producing genes in E. coli detected by this study is of great concern and highlights the need of infection control measures including antibacterial management and prompt identification of isolates with beta-lactamase-producing genes.

Health Concerns on Microbiological Quality of Bottled Drinking Water Sold in Dar es Salaam, Tanzania

Background:Dar es Salaam City has over 10 million habitants, who are constantly circumvented by water-borne diseases. The city experiences humid and hot weather throughout a year, which lead to high consumption of bottled drinking water because of being perceived as safer than tap or well water. Waterborne disease outbreaks still create havoc among the city habitants. This study determines heterotrophic plate count (HPC) values in bottled water and performs antimicrobial resistance tests on isolated microorganisms. Methods: A cross-sectional study was conducted. Fifty-four samples of bottled water were randomly purchased from shops, supermarkets and street vendors. HPC values were determined and microbial contaminants identified. The disk diffusion method was employed for testing antimicrobial resistance of microbial contaminants against four widely used antibiotics. Results: HPC values were variable (4.7 x102 to 7.0 x105 cfu/ml). Majority (86.7%) of analyzed samples revealed high HPC values. Four bacterial species were isolated and identified from 47 samples. Predominant bacterial contaminants were Brevundimonas vesicularis (54.5%), while Pseudomonas thomasii was only isolated from one brand A sample. Brand E samples had the highest HPC values (2.2 x 104 to 2.16 x105 cfu/ml) while F samples were free from microbial contaminants. A total of 21 (46.7%) bacterial isolates were resistant to commonly used antibiotics namely ciprofloxacin, ampicillin, cotrimoxazole and chloramphenicol. Conclusion: Of 54 analyzed bottled water samples, 47 had high HPC values. High rates of antibacterial resistance was exerted against ciprofloxacin (68.2%) and ampicillin (56%). This calls for responsible authorities to impose more stringent measures on in-process quality control among bottled water producers and indefatigably conduct post- production surveillance to avert the endemic water-borne outbreaks resulting from consumption of such products.

Helicobacter pylori resistance to antibiotics in Europe and its relationship to antibiotic consumption

ObjectiveResistance to antibiotics is the major cause of treatment failure of Helicobacter pylori infection. A study was conducted to assess prospectively the antibacterial resistance rates of H pylori in Europe...

Probiotics in the Intensive Care Unit

Probiotics are living microorganisms that, when ingested in adequate amounts, provide benefits to the host. The benefits include either a shortened duration of infections or decreased susceptibility to pathogens. Proposed mechanisms of beneficial effects include improving gastrointestinal barrier function, modification of the gut flora by inducing host cell antimicrobial peptides and/or local release of probiotic antimicrobial factors, competition for epithelial adherence, and immunomodulation. With increasing intensive care unit (ICU) antibacterial resistance rates and fewer new antibiotics in the research pipeline, focus has been shifted to non-antibiotic approaches for the prevention and treatment of nosocomial infections. Probiotics offer promise to ICU patients for the prevention of antibiotic-associated diarrhea, Clostridium difficile infections, multiple organ dysfunction syndrome, and ventilator-associated pneumonia. Our current understanding of probiotics is confounded by inconsistency in probiotic strains studied, optimal dosages, study durations, and suboptimal sample sizes. Although probiotics are generally safe in the critically ill, adverse event monitoring must be rigorous in these vulnerable patients. Delineation of clinical differences of various effective probiotic strains, their mechanisms of action, and optimal dosing regimens will better establish the role of probiotics in various disorders. However, probiotic research will likely be hindered in the future given a recent ruling by the U.S. Food and Drug Administration.

Antimicrobial resistance in Australia

Resistance to antimicrobials is a worldwide and increasing problem. Compared to most of its near neighbours Australia has comparatively low rates of antibacterial resistance. However, there are still significant problems, most notably methicillin-resistant <i>Staphylococcus aureus</i> (MRSA). Multi-resistant hospital-associated MRSA emerged in the late 1970s and become a significant problem on the eastern seaboard by the early 1980s. Subsequently, community-associated non-multi-resistant MRSA emerged, initially in Western Australia, and subsequently in other states, and is now widespread at increasing levels. Vancomycin-resistant enterococci (VRE) arrived in Australia in the mid 1990s, and remained at low levels until very recently, when there was a noticeable upsurge. Unlike other places in the world, the predominant type of VRE in Australia is VanB. Non-susceptibility to penicillin in <i>Streptococcus pneumoniae</i> appeared in Australia in the 1980s and appears to have stabilised. Extended-spectrum β-lactamase (ESBL) producing <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i> have been in Australia for more that 15 years, but until very recently have been remaining at low levels or even falling. The arrival of the CTX-M type of ESBL appears to be changing that decline. The other important but less common resistance is multi-resistant <i>Acinetobacter baumannii</i>, strains of which have caused outbreaks in several intensive care units across Australia.

Regional trends in β-lactam, macrolide, fluoroquinolone and telithromycin resistance among Streptococcus pneumoniae isolates 2001–2004

To determine global antibacterial resistance rates among community-acquired isolates of Streptococcus pneumoniae. Between 2001 and 2004, 20,142 S. pneumoniae isolates from 151 centres in 40 countries were collected and tested for susceptibility to common antibacterials in the PROTEKT surveillance study. The prevalence of beta-lactam and macrolide resistance did not change, but there was marked geographic variability. The most common macrolide resistance mechanism was ribosomal methylation mediated by erm(B), except in Canada, Greece and the USA where drug efflux mediated by mef(A) was predominant. The erythromycin minimum inhibitory concentration for mef(A) isolates increased significantly (P<0.001; chi2 test). The global prevalence of macrolide-resistant isolates positive for both erm(B) and mef(A) was 12.0% in 2003-2004; erm(B)+mef(A) strains were particularly common in South Korea (40.8%), South Africa (46.4%) and the USA (29.6%). Telithromycin was the most active antibacterial tested. Over the studied period, > or = 99.7% of all isolates and > 99% of erythromycin-resistant isolates, irrespective of genotype, were susceptible to telithromycin. These results confirm the high worldwide prevalence of resistance to commonly used antibacterial agents and multiple resistance phenotypes among clinical isolates of S. pneumoniae and suggest that high-level macrolide resistance is continuing to increase in most countries.

Oral β-lactams in the treatment of acute bacterial rhinosinusitis

Acute bacterial rhinosinusitis (ABRS) is a well-known complication of viral upper respiratory tract infection and is associated with a significant socioeconomic burden. Difficulties in diagnosis, a substantial spontaneous resolution rate, and growing concerns regarding antimicrobial resistance make the proper management of ABRS quite challenging. Treatment guidelines have been developed, taking into account the major bacterial pathogens, rates of antimicrobial resistance, spontaneous resolution rates, and pharmacokinetic and pharmacodynamic considerations. Optimal choices for initial treatment of ABRS in patients without prior antibacterial exposure include the oral β-lactam agents amoxicillin/clavulanate, cefdinir, cefpodoxime, and cefuroxime. Clinicians are encouraged to consider the local pathogen distribution and rates of antibacterial resistance in selecting therapy for ABRS.

Antibacterial resistance in Helicobacter pylori strains isolated from Bulgarian children and adult patients over 9 years

The aim of this study was to evaluate the primary, combined and post-treatment antibacterial resistance rates in 1205 Helicobacter pylori strains from non-treated (786 adults, 282 children) and treated (109 adults, 28 children) patients in Bulgaria. Susceptibility was tested by the limited agar dilution method. Overall primary resistance rates to metronidazole, clarithromycin, amoxicillin, tetracycline and both metronidazole and clarithromycin were respectively 15.0, 12.5, 1.5, 3.4 and 4.7% in children and 25.6, 12.6, 0.8, 5.2 and 4.9% in adults. Primary metronidazole resistance in adults was more common than in children, but the differences for other agents tested were not significant. Primary resistance rates were in the range of those reported worldwide. There was no significant increase in primary resistance rates from 1996/1999 to 2003/2004; however, clarithromycin resistance rates exhibited a slight tendency to increase. Post-treatment resistance to amoxicillin was detected in 1.6% of 63 strains. Post-treatment resistance to metronidazole was common (81.6%) and that to clarithromycin was considerable (36%). Alarming emergence of strains with triple resistance to amoxicillin, metronidazole and clarithromycin was found in two non-treated and three treated patients. The results motivate a larger and continuing surveillance of H. pylori resistance in Bulgaria and worldwide.

Antibacterial susceptibility among Streptococcus pneumoniae isolated from paediatric and adult patients as part of the PROTEKT US study in 2001-2002.

One of the main factors commonly associated with antibacterial resistance among Streptococcus pneumoniae is the age of the patient. The highest rates of resistance have often been reported among isolates from young children. Data from the PROTEKT US (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin in the United States) surveillance study were examined to determine the level of antibacterial resistance among S. pneumoniae isolates collected in 2001-2002 from different patient age groups in the USA. A total of 10 012 clinical isolates of S. pneumoniae were submitted by 242 centres across the USA and categorized into four patient age groups: infants (0-2 years, n = 1556), children (3-14 years, n=1125), adults (15-64 years, n=4058) and elderly adults (> or =65 years, n = 3067) (age unknown n=206). With the exception of the fluoroquinolones and linezolid, rates of antibacterial resistance were highest among infants and decreased with increasing patient age. Resistance to penicillin ranged from 33.6% among infants to 17.5% among elderly adults, and erythromycin resistance ranged from 41.1% among infants to 24.0% among adults. In contrast, levofloxacin resistance increased with patient age (from 0.1% to 1.6%). The highest rates of susceptibility were noted for telithromycin and linezolid (> or =99.6% and > or =99.8% susceptible isolates, respectively). The PROTEKT US study data confirmed that the highest antibacterial resistance rates were associated with isolates collected from young children (0-2 years). Telithromycin may offer a reliable alternative to first-line drugs in the empirical treatment of community-acquired respiratory tract infections.