Antibiotic resistance

Sensitive immunoenzyme assay for the detection of antibiotic flumequine in honey

Fluoroquinolone antibiotics are used to cure and protect bees and apiaries from infections. Consequently, they may contaminate honey and other products of beekeeping. In this study, a highly sensitive immunoenzyme assay (EIA) was for the first time developed for the determination of a fluoroquinolone flumequine (FLU) in honey. The EIA was carried out in an indirect competitive format with colorimetric detection. The analysis was characterized by a low limit of detection of 30 pg mL-1. The polyclonal antibodies used showed no cross-reactivity with 24 other (fluoro)quinolones; the assay was highly specific only toward FLU. Different coating FLU-protein conjugates were tested to achieve the most sensitive competitive immunodetection. A highly simplified and rapid (3-5 min) sample preparation was proposed based on the 100-300 times dilution of honey by a buffer. The developed EIA has been tested to detect FLU in honey of different origins, namely acacia, flower, buckwheat, chestnut, and linden honey. It has been demonstrated that 76.2-115.9% of FLU could be determined by the assay. The versatility, simplicity, and rapidity of the EIA enable us to propose this method as an effective tool to control the contamination of honey.

Presence of the blaTEM Gene in Commensal Neisseria spp.: A Possible Cause for the Acquired Drug Resistance Among Pathogenic Respiratory Bacteria

Background The oral microbiome consists of various bacterial genera, with Neisseria spp. being a prominent part of this niche. While Neisseria gonorrhoeae and Neisseria meningitidis are human-restricted pathogens, non-pathogenic Neisseria species like Neisseria sicca, Neisseria perflava, etc., are primarily commensals that can also behave as opportunistic pathogens. With increasing penicillin resistance in commensal Neisseria, there is a concern that these bacteria might harbor resistance genes that can be transferred to other pathogens. This study aimed to characterize the blaTEM gene (encodes for the plasmid-mediated β-lactamase enzyme that hydrolyzes the β-lactam ring) of commensal Neisseria spp. isolated from respiratory samples. Methodology The research was conducted in the Department of Clinical Microbiology at Sri Ramachandra University, Chennai. The specimens used were sputum and throat swabs, which were subjected to a series of phenotypic methods and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) for speciation. The antibiogram was determined using the Kirby-Bauer disk diffusion method, and a PCR assay was utilized to identify the blaTEM gene responsible for β-lactamase production. Results Out of 274 processed samples, 65 unique commensal Neisseria spp. were identified. The study highlighted the presence of the blaTEM gene in 93.9% (61) of the isolates, which is responsible for β-lactamase production. All isolates exhibited resistance to penicillin. Most blaTEM-positive commensal Neisseria spp. were susceptible to cefuroxime (83.6%), ceftriaxone (85.2%), and cefotaxime (85.2%). The high prevalence of the blaTEM gene in commensal Neisseria is alarming. The gene, found on plasmids, could potentially transfer to other related species like Neisseria gonorrhoeae and Neisseria meningitidis, as well as other Gram-negative bacilli. Conclusion The presence of resistance genes in commensal bacteria is of concern, as they might be reservoirs for resistance transfer to pathogenic strains. The study emphasizes the importance of continuous monitoring and deeper investigations into commensal bacteria, emphasizing the need for a broader community screening approach to understand resistance mechanisms in the normal microbiome.

Antimicrobial resistance and virulence profiles of Enterobacterales isolated from two-finger and three-finger sloths (Choloepus hoffmanni and Bradypus variegatus) of Costa Rica

Background

Wildlife has been recently recognized as an environmental reservoir for antimicrobial resistance (AMR). However, less information on this topic is available in animals released back into the wild after rehabilitation in wildlife facilities, compared with studies performed exclusively in captive or free-ranging wildlife. This study aimed to evaluate the potential influence of captivity and/or treatment while in captivity of wild sloths on the AMR and virulence profiles of sloths' Enterobacterales.

Methods

Oral and rectal swab samples were collected from 39 two-finger (Choloepus hoffmanni) and three-finger sloths (Bradypus variegatus) of Costa Rica (n = 78) and analyzed using conventional bacteriological techniques. A generalized linear mixed model was applied to estimate the isolates' multiple antimicrobial resistance and virulence indices as a function of animal status.

Results

A considerable level of resistance was detected, especially for Citrobacter youngae and Escherichia coli, with 17.5% of isolates classified as multidrug-resistant. Virulence indices of isolates from rehabilitated sloths were significantly higher than the ones from sloths being hand-reared for shorter periods.

Conclusions

To our knowledge, this is the first description of sloths' antimicrobial resistant Enterobacterales, suggesting that sloths' rehabilitation and consequent exposure to humans, may promote the selection of bacteria with higher virulence. Ultimately, these bacteria may represent a threat to human and animal health due to their zoonotic potential and AMR and virulence profiles.

Non-contiguous multifocal vertebral osteomyelitis caused by Serratia marcescens

Serratia marcescens is a common nosocomial infection but a rare cause of osteomyelitis and more so of vertebral osteomyelitis. Vertebral osteomyelitis caused by this organism has been reported in few studies. We report a case of S. marcescens vertebral discitis and osteomyelitis affecting multiple non-contiguous vertebras. Although Staphylococcus aureus is the most common cause of vertebral osteomyelitis, rare causes, such as S. marcescens, need to be considered, especially when risk factors such as intravenous heroin use, post-spinal surgery and immunosuppression are present. Therefore, blood culture and where necessary biopsy of the infected region should be undertaken to establish the causative organism and determine appropriate antibiotic susceptibility. Prompt diagnosis of S. marcescens vertebral osteomyelitis followed by the appropriate treatment can achieve successful outcomes.

Mathematical modeling on bacterial resistance to multiple antibiotics caused by spontaneous mutations

We formulate a mathematical model that describes the population dynamics of bacteria exposed to multiple antibiotics simultaneously, assuming that acquisition of resistance is through mutations due to antibiotic exposure. Qualitative analysis reveals the existence of a free-bacteria equilibrium, resistant-bacteria equilibrium and an endemic equilibrium where both bacteria coexist.

The use of platensimycin and platencin to fight antibiotic resistance

Infectious diseases are known as one of the most life-threatening disabilities worldwide. Approximately 13 million deaths related to infectious diseases are reported each year. The only way to combat infectious diseases is by chemotherapy using antimicrobial agents and antibiotics. However, due to uncontrolled and unnecessary use of antibiotics in particular, surviving bacteria have evolved resistance against several antibiotics. Emergence of multidrug resistance in bacteria over the past several decades has resulted in one of the most important clinical health problems in modern medicine. For instance, approximately 440,000 new cases of multidrug-resistant tuberculosis are reported every year leading to the deaths of 150,000 people worldwide. Management of multidrug resistance requires understanding its molecular basis and the evolution and dissemination of resistance; development of new antibiotic compounds in place of traditional antibiotics; and innovative strategies for extending the life of antibiotic molecules. Researchers have begun to develop new antimicrobials for overcoming this important problem. Recently, platensimycin - isolated from extracts of Streptomyces platensis - and its analog platencin have been defined as promising agents for fighting multidrug resistance. In vitro and in vivo studies have shown that these new antimicrobials have great potential to inhibit methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae by targeting type II fatty acid synthesis in bacteria. Showing strong efficacy without any observed in vivo toxicity increases the significance of these antimicrobial agents for their use in humans. However, at the present time, clinical trials are insufficient and require more research. The strong antibacterial efficacies of platensimycin and platencin may be established in clinical trials and their use in humans for coping with multidrug resistance may be allowed in the foreseeable future.

An acidic phospholipase A₂ with antibacterial activity from Porthidium nasutum snake venom

Snake venoms are complex mixtures of proteins among which both basic and acidic phospholipases A(2) (PLA(2)s) can be found. Basic PLA(2)s are usually responsible for major toxic effects induced by snake venoms, while acidic PLA(2)s tend to have a lower toxicity. A novel PLA(2), here named PnPLA(2), was purified from the venom of Porthidium nasutum by means of RP-HPLC on a C18 column. PnPLA(2) is an acidic protein with a pI of 4.6, which migrates as a single band under both non-reducing and reducing conditions in SDS-PAGE. PnPLA(2) had a molecular mass of 15,802.6 Da, determined by ESI-MS. Three tryptic peptides of this protein were characterized by HPLC-nESI-MS/MS, and N-terminal sequencing by direct Edman degradation showing homology to other acidic PLA(2)s from viperid venoms. PnPLA(2) displayed indirect hemolytic activity in agarose erythrocyte-egg yolk gels and bactericidal activity against Staphylococcus aureus in a dose-dependent manner, with a MIC and MBC of 32 μg/mL. In addition, PnPLA(2) showed a potent inhibitory effect on platelet aggregation with doses up to 40 μg/mL. This acidic PLA(2), in contrast to basic enzymes isolated from other viperid snake venoms, was not cytotoxic to murine skeletal muscle myoblasts C(2)C(12). This is the first report on a bactericidal protein of Porthidium nasutum venom.

Implementation and outcomes of a hospital-wide computerised antimicrobial stewardship programme in a large medical centre in Taiwan

Antibiotic stewardship is important to address the problem of antimicrobial resistance, but a practical and sustainable strategy to provide stewardship in a large hospital setting is lacking. We developed a hospital-wide computerised antimicrobial approval system (HCAAS) to guide the use of antimicrobial agents in late 2004 in a 3500-bed medical centre in Taiwan. The objective of this study was to evaluate the impacts of HCAAS on the hospital from 2003 to 2009. Following HCAAS deployment, the gradients of consumption over time during the study period of third- and fourth-generation cephalosporins, fluoroquinolones and glycopeptides fell significantly, whilst that of carbapenems increased. The amount and expenditure of antimicrobial use did not increase with the overall healthcare-associated infection rate, and inpatient mortality rate remained stable with a slight decreasing trend. The rate of meticillin-resistant Staphylococcus aureus started to decline in 2002 and continued after HCAAS deployment. There was an increasing isolation of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae, presumably leading to the increased use of carbapenems. The isolation rate of Clostridium difficile from patients who developed diarrhoea after antimicrobial therapy did not change over the years, with a mean annual rate of 10.0% after the implementation of HCAAS. HCAAS along with strict infection control measures is necessary to reduce the spread of resistant organisms within the hospital. HCAAS is a sustainable system for providing antibiotic stewardship and exerts a positive impact on the hospital by reducing antimicrobial consumption and expenditure whilst not compromising healthcare quality.

Measuring appropriate use of antibiotics in pyelonephritis in Belgian hospitals

Inappropriate use of antibiotics can induce antibiotic resistance, treatment failure, increased costs and even mortality. We developed a methodology for measuring guideline compliance of hospital antibiotic prescriptions in community-acquired acute pyelonephritis in Belgium. The claims and clinical data of all Belgian hospitalizations for community-acquired acute pyelonephritis were extracted from a nationwide administrative database. In a clinically homogeneous subset of patients, the percentage of patients who received a guideline-compliant prescription was calculated according to prescription guidelines disseminated in Belgium. In the group of non-pregnant adult female patients, 31% of the prescriptions were not in strict compliance with the guideline. Interhospital variability ranged from 0% to 100% compliance. We conclude that administrative databases can be used to analyze antibiotic prescription behavior in hospitals for homogeneous and clinically relevant patient groups. The interhospital variability observed in Belgian hospitals indicate that there is a clear room for improvement.

The effect of rehabilitation of northern elephant seals (Mirounga angustirostris) on antimicrobial resistance of commensal Escherichia coli

The aim of this study was to determine if antimicrobial drug use increases resistance of commensal gastrointensinal Escherichia coli of wild northern elephant seals (Mirounga angustirostris) treated in rehabilitation, and, if so, identify the risk factors involved. Minimum inhibitory concentration (MIC) levels of twelve antimicrobial drugs were determined for 289 E. coli isolates from 99 seals sampled at admission and 277 isolates obtained at release from rehabilitation using broth microdilution. Prevalence of E. coli antimicrobial resistance, MIC(50), MIC(90), and clustering of MIC values were determined for seals and the data were analyzed using Fisher's exact test, ordinal logistic regression and negative binomial regression. At release from rehabilitation 77.8% of the seals had antimicrobial resistant E. coli compared to 38.4% of the seals at admission. The MIC(90) for amoxicillin-clavulanic acid, chloramphenicol, enrofloxacin, ticarcillin-clavulanic acid, and trimethoprim-saulfamethoxazole were at levels considered to be sensitive at admission but they increased to levels of resistance at release. E. coli were grouped into four clusters by their MIC values, with increasing levels of resistance going from Cluster 1 to 4. A primary risk factor associated with the probability of a seal having E. coli in Clusters 3 and 4 was time in rehabilitation, regardless of whether the animal received treatment with antimicrobial drugs, suggesting nosocomial infection. The results of this study provide evidence that increased levels of hygiene and appropriate use of antimicrobial therapy might be important in the rehabilitation of wild animals to prevent rise in the prevalence of antimicrobial resistant bacteria.

A comparison of antibiotic resistance integrons in cattle from separate beef meat production systems at slaughter

AIMS

To compare antibiotic resistance integrons in cattle from three separate grass-fed, grain-fed and certified organic cattle production systems at slaughter.

METHODS AND RESULTS

In this study 198 samples from three separate cattle production systems were tested by PCR for the presence of class 1 and class 2 integrons. Integron-containing bacteria were readily isolated from pen faeces and hide samples regardless of production system. Lower numbers of integron-containing bacteria were isolated from the remaining sample types. Ninety-one class 1 and 34 class 2 integron-containing bacteria were isolated. Characterization of the integrons demonstrated a high degree of similarity across the three production systems with aadA1 and aadA2 routinely present. Integrons harbouring the cassette array cmlA5-bla(OXA-10)-aadA1 and the putative insertion sequence IS1066 were isolated from organic and grass-fed cattle and have not been described previously.

CONCLUSIONS

Integrons carrying antibiotic resistance genes were common in cattle from differing production systems at slaughter and the likelihood of presence appears unrelated to the production system.

SIGNIFICANCE AND IMPACT OF THE STUDY

Similar integron arrays are present in different cattle production systems suggesting that their presence may be independent of production practices. This is the first report of two novel integron structures present in Aeromonas.

Cefepime versus ceftazidime: considerations for empirical use in critically ill patients

Sepsis and nosocomial infections continue to be a significant problem in intensive care, contributing heavily to mortality and prolonged hospital stay. Early and appropriate antibiotic therapy is critical for optimising outcomes. However, the emergence of highly resistant bacteria, coupled with reduced development of novel antibiotics, means that there is a real threat of development of untreatable nosocomial infections. Cefepime and ceftazidime are broad-spectrum cephalosporins that are widely used to treat Gram-negative nosocomial infections in critically ill patients. Available data suggest that cefepime may have advantages over ceftazidime owing to a broader spectrum of activity and reduced potential for development of bacterial resistance. However, whether either of these agents is superior can only be determined by a head-to-head study evaluating clinical and bacteriological outcomes. Such a study to determine whether apparent differences translate into clinically relevant differences in outcome is indicated.

Therapeutic implications of macrolide resistance in pneumococcal community-acquired lower respiratory tract infections

Macrolide anti-bacterials are widely used for the empirical treatment of lower respiratory tract infections (RTIs) due to their activity against Streptococcus pneumoniae and other common respiratory pathogens and good safety/tolerability profile. However, the prevalence of macrolide resistance, particularly pneumococcal macrolide resistance, is increasing all around the world. The mechanisms underlying macrolide resistance include efflux pump, methylase activity and, less commonly, ribosomal mutation, which produce differing levels of resistance. Growth in macrolide resistance has been linked to the increased use of these agents, and several risk factors for the development of resistance have been identified. There are emerging data to suggest that in vitro macrolide resistance may increase the likelihood of treatment failure in patients with lower RTIs. However, at present, treatment failure is rare and randomised; intervention-based trials investigating the impact of anti-bacterial resistance on clinical outcomes are lacking. Strategies to promote appropriate use of macrolides and other anti-bacterials are needed, both to maximise therapeutic impact and to minimise the development of resistance. Furthermore, there is a need for alternative anti-bacterial agents which have high efficacy against respiratory pathogens (including resistant strains) and a low potential to induce resistance.

Antimicrobial resistance among non-fermentative Gram-negative bacilli isolated from the respiratory tracts of Italian inpatients: a 3-year surveillance study by the Italian Epidemiological Survey

The Italian Epidemiological Survey evaluated antibiotic susceptibility of non-fermentative Gram-negative bacilli isolated from inpatient respiratory-tract specimens collected throughout Italy during 1997-1999. The minimal inhibitory concentrations of 14 antibiotics for 1474 Pseudomonas aeruginosa strains, 307 Stenotrophomonas maltophilia strains and 114 Acinetobacter baumannii strains were determined in 57 clinical microbiology laboratories by means of a standardised micro-dilution method. The most active drugs against P. aeruginosa isolates were meropenem (81% susceptible) and amikacin (80% susceptible). Imipenem and meropenem proved to be the only agents active against A. baumannii isolates, although 13 and 16%, respectively, of strains were resistant to these drugs. Trimethoprim-sulphamethoxazole (TMP-SMZ) showed activity only against S. maltophilia isolates (83% susceptible). A total of 185 multidrug-resistant P. aeruginosa isolates (resistant to piperacillin, ceftazidime, gentamicin, and imipenem) were found. Resistance rates and trends showed consistent regional variations, including sharp increases from 1997 to 1999 in imipenem resistance among P. aeruginosa isolates from central and southern Italy.

Empiric Therapy of Community-Acquired Pneumonia

This article discusses the key clinical aspects of empiric therapy of community-acquired pneumonia (CAP). Antibiotic selection, severity of CAP, single vs multiple pathogens, pharmacokinetic considerations, antibiotic resistance, i.v. vs oral antibiotic therapy for CAP, oral therapy for non-ICU hospitalized patients with CAP, beta-lactams, macrolides, ketolides, doxycycline, respiratory quinolones, and pharmacoeconomic implications are discussed.

Isolation and characterization of integron-containing bacteria without antibiotic selection

The emergence of antibiotic resistance among pathogenic and commensal bacteria has become a serious problem worldwide. The use and overuse of antibiotics in a number of settings are contributing to the development of antibiotic-resistant microorganisms. The class 1 and 2 integrase genes (intI1 and intI2, respectively) were identified in mixed bacterial cultures enriched from bovine feces by growth in buffered peptone water (BPW) followed by integrase-specific PCR. Integrase-positive bacterial colonies from the enrichment cultures were then isolated by using hydrophobic grid membrane filters and integrase-specific gene probes. Bacterial clones isolated by this technique were then confirmed to carry integrons by further testing by PCR and DNA sequencing. Integron-associated antibiotic resistance genes were detected in bacteria such as Escherichia coli, Aeromonas spp., Proteus spp., Morganella morganii, Shewanella spp., and urea-positive Providencia stuartii isolates from bovine fecal samples without the use of selective enrichment media containing antibiotics. Streptomycin and trimethoprim resistance were commonly associated with integrons. The advantages conferred by this methodology are that a wide variety of integron-containing bacteria may be simultaneously cultured in BPW enrichments and culture biases due to antibiotic selection can be avoided. Rapid and efficient identification, isolation, and characterization of antibiotic resistance-associated integrons are possible by this protocol. These methods will facilitate greater understanding of the factors that contribute to the presence and transfer of integron-associated antibiotic resistance genes in bacterial isolates from red meat production animals.

Prevention and management of antibacterial resistance for primary care patients with respiratory tract infections

This review examines the problem of increasing antibacterial resistance among the pathogens commonly associated with community-acquired respiratory tract infections, particularly Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The increases in morbidity, mortality, and treatment cost associated with increased resistance to available antibiotics are challenging prescribers to find more effective therapeutic strategies. A MEDLINE search of the literature from 1966 to the present was performed to seek data relevant to the issue of resistance, especially the negative effects on patient outcomes and costs of therapy. Several observations and conclusions emerged. Data are lacking on local resistance patterns, broad-spectrum agents are overprescribed when narrower-spectrum choices would be more appropriate, a need exists for educational programs to encourage restricting drug use and changing prescribing habits, and there is a need for new antibiotic choices. The best antibiotic options are agents with a tailored spectrum of activity that are targeted at particular respiratory tract pathogens and have low potential to select for resistant organisms.

All great truths are iconoclastic: selective decontamination of the digestive tract moves from heresy to level 1 truth

OBJECTIVE

The objective was to compare evidence of the effectiveness, costs and safety of the traditional parenteral antibiotic-only approach against that gathered from 53 randomised trials involving more than 8,500 patients and six meta-analyses on selective decontamination of the digestive tract (SDD) to control infection on the intensive care unit (ICU). PHILOSOPHY: Traditionalists believe that all infections are due to breaches of hygiene except those established in the first 2 days, and that all micro-organisms can cause death. In contrast, newer insights show that transmission via the hands of carers are responsible only for infections occurring after one week, and that only a limited range of 15 potential pathogens contribute to mortality. INTERVENTIONS TO PREVENT ICU INFECTION: The traditional approach is based on hand disinfection aiming at the prevention of transmission of all micro-organisms, to control all infections that occur after 2 days on the ICU. The second feature is the restrictive use of systemic antibiotics, only in cases of microbiologically proven infection. In contrast, SDD aims to control the three types of infection: primary, secondary endogenous and exogenous due to 15 potential pathogens. The classical SDD tetralogy comprises four components: (i) a parenteral antibiotic, cefotaxime, administered for three days to prevent primary endogenous infections typically occurring "early"; (ii) the oropharyngeal and enteral antimicrobials, polymyxin E, tobramycin and amphotericin B administered in throat and gut throughout the treatment on the ICU to prevent secondary endogenous infections tending to develop "late"; (iii) a high standard of hygiene to control transmission of potential pathogens; and (iv) surveillance samples of throat and rectum to monitor the efficacy of the treatment.

ENDPOINTS

(i) Infectious morbidity; (ii) mortality; (iii) antimicrobial resistance; and (iv) costs.

RESULTS

Properly designed trials on hand disinfection have never demonstrated a reduction in either pneumonia and septicaemia, or mortality. Two randomised trials using restrictive antibiotic policies failed to show a survival benefit at 28 days. In both trials the proportion of resistant isolates obtained from the lower ways was >60% despite significantly less use of antibiotics in the test group. A formal cost effectiveness analysis of the traditional antibiotic policies has not been performed. On the other hand, two meta-analyses have shown that SDD reduces the odds ratio for lower airway infections to 0.35 (0.29-0.41) and mortality to 0.80 (0.69-0.93), with a 6% overall mortality reduction from 30% to 24%. No increase in the rate of super infections due to resistant bacteria could be demonstrated over a period of 20 years of clinical research. Four randomised trials found the cost per survivor to be substantially lower in patients receiving SDD than for those traditionally managed.

CONCLUSIONS

The traditionalists still rely on level 5 evidence, i.e. expert opinion, with a grade E recommendation, whilst the proponents of SDD are able to cite level 1 evidence allowing a grade A recommendation in their attempts to control infection on the ICU. The main reason for SDD not being widely used is the primacy of opinion over evidence.

The use and resistance to antibiotics in the community

The frequency of resistance to antibiotics among common community-acquired pathogens, and the number of drugs to which they are resistant have been increasing worldwide. The relationship between antibiotic usage and resistance is strongly supported by data from several studies. Countries with the highest per capita antibiotic consumption have the highest resistance. The emergence of penicillin-resistant Streptococcus pneumoniae is related to high consumption of antibiotics in general, as well as to increased use of aminopenicillins and/or probably to wider use of oral cephalosporins. Increased consumption of macrolides, especially the long-acting ones, correlates significantly with the level of macrolide resistance of group A streptococci and S. pneumoniae while increased use of oral cephalosporins might be associated with the increase of beta-lactamase-producing strains of Moraxella catarrhalis. Trimethoprim/sulphamethoxazole resistance is strongly associated with resistance to penicillin. A rise in consumption of fluoroquinolones is consonant with a higher rate of resistance to quinolones of S. pneumoniae, Escherichia coli and other Gram-negative bacteria. Paediatric bacterial isolates are more often resistant to various antimicrobial agents than isolates from adult patients; this higher resistance rate may be due to more frequent antimicrobial treatments in children, and extensive child to child transmission. Reliable data on antimicrobial consumption and resistance should form a basis for national policies devised to reduce the resistance of microorganisms to antibiotics.

Antibiotics and the development of resistant microorganisms. Can homeopathy be an alternative?

Antibiotic resistance is a global public health problem. Once confined primarily to hospitals it is now increasingly common in primary care. The prevalence of resistant bacteria is rising, and organisms resistant to almost all antibiotics have been identified. The main causes are indiscriminate prescribing and the use of antibiotics in animal feeds and other agricultural applications. Policies to restrict use of antibiotics have had limited success. Homeopathy may have a role to play in combating the development of antibiotic resistance. Clinical research suggests that homeopathy is effective in the treatment of upper respiratory tract infections in children, a frequent cause of inappropriate antibiotic prescribing. The EU recommends the use of homeopathy in organic animal husbandry, and it is used by significant numbers of farmers. At present there is little data on the effectiveness of homeopathy in this setting. Further research should be done.

In vitro and in vivo pharmacodynamic properties of the fluoroquinolone ibafloxacin

The pharmacodynamic properties of a new veterinary fluoroquinolone antimicrobial agent, ibafloxacin, were evaluated. Minimal inhibitory concentrations (MIC), time-kill kinetics, postantibiotic effect (PAE) and postantibiotic subminimal inhibitory concentration effects (PA-SME) were determined against pathogenic canine Gram-negative and Gram-positive bacterial isolates from dermal, respiratory and urinary tract infections. The synergistic interactions between ibafloxacin and its main metabolite, 8-hydroxy-ibafloxacin were investigated. Finally, the efficacy of ibafloxacin was tested in in vivo canine infection models. Ibafloxacin had good activity against Pasteurella spp., Escherichia coli, Klebsiella spp., Proteus spp. and Staphylococcus spp. (MIC90=0.5 microg/mL), moderate activity against Bordetella bronchiseptica, Enterobacter spp. and Enterococcus spp. (MIC50=4 microg/mL) and low activity against Pseudomonas spp. and Streptococcus spp. The time-killing analysis confirmed that ibafloxacin was bactericidal with a broad spectrum of activity. The PAE and PA-SME were between 0.7-2.13 and 1-11.5 h, respectively. Finally, studies in dog models of wound infection and cystitis confirmed the efficacy of once daily oral ibafloxacin at a dosage of 15 mg/kg. Additional studies are needed to better define the importance of AUC/MIC (AUIC) and Cmax/MIC ratios on the outcome of fluoroquinolone therapy in dogs.

Antimicrobial activity of broad-spectrum agents tested against Gram-negative bacilli resistant to ceftazidime: report from the SENTRY Antimicrobial Surveillance Program (North America, 2001)

To assess the effect of ceftazidime resistance on the activity of other antimicrobial agents, 4,175 Gram-negative bacilli isolates, designated as ceftazidime-susceptible (3,759, 90%) or -resistant (416, 10%) were tested against a panel of nine agents. Cefepime was the most active of the agents tested, against both ceftazidime-susceptible and -resistant isolates, with a particularly low incidence (0.3%, 10/3152 isolates) of resistance among the Enterobacteriaceae. Tobramycin had the best activity against Pseudomonas aeruginosa and ticarcillin/clavulanate was the least active of the tested agents. This study confirms the need for constant monitoring of in vitro antimicrobial efficacy to direct empiric treatment regimens.

Serratia bacteremia in a large university hospital: trends in antibiotic resistance during 10 years and implications for antibiotic use

OBJECTIVE

To identify antibiotic resistance trends and risk factors for resistance of Serratia species to third-generation cephalosporins.

DESIGN

Retrospective survey of medical records.

SETTING

A 2,200-bed, tertiary-care hospital.

PATIENTS

One hundred twenty-two patients with Serratia bacteremia between January 1991 and June 2001.

METHODS

Infectious disease physicians collected data from medical records regarding patient demographics, underlying disease or condition, portal of entry, microorganism, antibiogram, complications, antibiotics received, and outcome.

RESULTS

Among 122 Serratia isolates, 117 (95.9%) were Serratia marcescens and 110 (90.2%) were of nosocomial origin. During the study period, the 122 isolates showed a high rate of resistance to third-generation cephalosporins (45.9%) and extended-spectrum penicillins (56.6%). The resistance rate to ciprofloxacin was 32.0%. The resistance rate to third-generation cephalosporins increased from 31.7% for 1991 to 1995 to 54.9% for 1996 to 1998 and 50.0% for 1999 to 2001. In the multivariate analysis, prior use of a second-generation cephalosporin (adjusted odds ratio [OR], 5.90; 95% confidence interval [CI90], 1.41 to 24.6; P = .015) or a third-generation cephalosporin (OR, 3.26; CI95, 1.20 to 8.87; P = .020) was a strong independent risk factor for resistance to third-generation cephalosporins. The overall case-fatality rate was 25.4% (Serratia bacteremia-related case-fatality rate, 13.1%).

CONCLUSION

Prior use of a second- or third-generation cephalosporin was the most important risk factor for bacteremia with Serratia resistant to third-generation cephalosporins, suggesting the need for antibiotic control. The potential role of patient-to-patient spread could not be fully evaluated in this retrospective study.