Chronological Change of Resistance to β-Lactams in Salmonella enterica serovar Infantis Isolated from Broilers in Japan

Epidemiologic surveillance study was conducted in southern Japan to determine the antimicrobial resistance phenotypes and characterize the β-lactamase genes and the plasmids harboring these genes in Salmonella enterica serovar Infantis (S. Infantis) isolates from broilers. Between January, 2007 and December, 2008, a total of 1,472 fecal samples were collected and examined at the Laboratory of Veterinary Public Health, Kagoshima University, Japan. In 93 (6.3%) isolates recovered, 33 (35.5%) isolates showed resistance to cefotaxime, an extended-spectrum cephalosporin (ESC), conferred by TEM-20, TEM-52 and CTX-M-25 extended-spectrum β-lactamases (ESBLs). In addition to ESC-resistance, eight (8.6%) isolates exhibited resistance to cefoxitin mediated by CMY-2 AmpC β-lactamase. Plasmid analysis and polymerase chain reaction replicon typing revealed the bla TEM-20 and bla CMY-2 genes were associated with IncP plasmids, bla TEM-52 was linked with a non-typable plasmid and bla CTX-M-25 was carried by an IncA/C plasmid. Non-β-lactam resistance to streptomycin, sulfamethoxazole, and oxytetracycline encoded by the aadA1, sul1, and tet(A) genes, respectively, was found in 86 (92.5%) isolates. Resistance to kanamycin and ofloxacin was exhibited in 12 (12.9%) and 11 (11.8%) isolates, respectively, the former was mediated by aphA1-Iab. These data indicate that S. Infantis isolates producing ESBLs and AmpC β-lactamase have spread among broiler farms in Japan. These data demonstrated that the incidence of ESC-resistant S. Infantis carrying bla TEM-52 remarkably increased and S. Infantis strains harboring bla CMY-2, bla TEM-20, or bla CTX-M-25 genes emerged from broilers in Japan for the first time in 2007 and 2008.

A brief multi-disciplinary review on antimicrobial resistance in medicine and its linkage to the global environmental microbiota

The discovery and introduction of antimicrobial agents to clinical medicine was one of the greatest medical triumphs of the 20th century that revolutionized the treatment of bacterial infections. However, the gradual emergence of populations of antimicrobial-resistant pathogenic bacteria resulting from use, misuse, and abuse of antimicrobials has today become a major global health concern. Antimicrobial resistance (AMR) genes have been suggested to originate from environmental bacteria, as clinically relevant resistance genes have been detected on the chromosome of environmental bacteria. As only a few new antimicrobials have been developed in the last decade, the further evolution of resistance poses a serious threat to public health. Urgent measures are required not only to minimize the use of antimicrobials for prophylactic and therapeutic purposes but also to look for alternative strategies for the control of bacterial infections. This review examines the global picture of antimicrobial resistance, factors that favor its spread, strategies, and limitations for its control and the need for continuous training of all stake-holders i.e., medical, veterinary, public health, and other relevant professionals as well as human consumers, in the appropriate use of antimicrobial drugs.

Increasing prevalence and diversity of ESBL/AmpC-type β-lactamase genes in Escherichia coli isolated from veal calves from 1997 to 2010

OBJECTIVES

Several studies on faecal carriage of extended-spectrum β-lactamase (ESBL)/AmpC-producing Escherichia coli have been performed in cattle, but little is known about faecal carriage in veal calves. This study describes the prevalence and molecular characteristics of ESBL/AmpC genes in E. coli isolated from faecal samples of veal calves from 1997 to 2010.

METHODS

Pooled faecal samples were inoculated using selective enrichment broth and subsequently selective MacConkey agar. All isolates with reduced susceptibility to cefotaxime were screened by PCR and sequencing analysis for the presence of ESBL/AmpC genes.

RESULTS

The prevalence of E. coli with reduced susceptibility to cefotaxime showed a discontinuous increasing trend, ranging from 4% in 1998 and 1999 to 39% in 2010. Promoter mutations of the chromosomal ampC gene were present in all years. In 2000, ESBL genes blaCTX-M-1, blaTEM-52 and blaTEM-20 were first observed. Before 2005 the majority of E. coli with reduced susceptibility to cefotaxime harboured ampC promoter mutations. From 2005 onwards the majority harboured blaCTX-M genes, of which blaCTX-M-1 was the most abundant, followed by blaCTX-M-14 and blaCTX-M-15. The diversity of blaCTX-M genes gradually increased from one variant in 2000 to six variants in 2010. The prevalence of blaTEM-52 was relatively low, but it was detected from 2000 onwards. blaCMY and blaSHV were found sporadically.

CONCLUSIONS

The prevalence and molecular diversity of genes encoding cefotaxime resistance in E. coli isolated from veal calves over a 14 year period showed an increasing trend. From 2005 onwards, blaCTX-M genes were most abundant, especially blaCTX-M-1.

Current microbial isolates from wound swabs, their culture and sensitivity pattern at the niger delta university teaching hospital, okolobiri, Nigeria

Background: Wound infections continue to be problematic in clinical practice where empiric treatment of infections is routine. Objectives: A retrospective cross-sectional study to determine the current causative organisms of wound infections and their antibiotic susceptibility patterns in the Niger Delta University Teaching Hospital (NDUTH), Okolobiri, Bayelsa State of Nigeria. Methods: Records of wound swabs collected from 101 patients with high suspicion of wound infection were analysed. Smears from the wound swabs were inoculated on appropriate media and cultured. Bacterial colonies were Gram stained and microscopically examined. Biochemical tests were done to identify pathogen species. The Kirby-Bauer disk diffusion method was used for antibiotic testing. Results: Prevalence of wound infection was 86.13% (CI: 79.41–92.85). Most bacteria were Gram negative bacilli with Pseudomonas aeruginosa being the most prevalent pathogen isolated. The bacterial isolates exhibited a high degree of resistance to the antibiotics tested (42.8% to 100% resistance). All isolates were resistant to cloxacillin. Age group and sex did not exert any effect on prevalence, aetiological agent or antimicrobial resistance pattern. Conclusion: We suggest a multidisciplinary approach to wound management, routine microbiological surveillance of wounds, rational drug use and the institution of strong infection control policies.

The human microbiome as a reservoir of antimicrobial resistance

The gut microbiota is amongst the most densely populated microbial ecosystem on earth. While the microbiome exerts numerous health beneficial functions, the high density of micro-organisms within this ecosystem also facilitates horizontal transfer of antimicrobial resistance (AMR) genes to potential pathogenic bacteria. Over the past decades antibiotic susceptibility testing of specific indicator bacteria from the microbiome, such as Escherichia coli, has been the method of choice in most studies. These studies have greatly enlarged our understanding on the prevalence and distribution of AMR and associated risk factors. Recent studies using (functional) metagenomics, however, highlighted the unappreciated diversity of AMR genes in the human microbiome and identified genes that had not been described previously. Next to metagenomics, more targeted approaches such as polymerase chain reaction for detection and quantification of AMR genes within a population are promising, in particular for large-scale epidemiological screening. Here we present an overview of the indigenous microbiota as a reservoir of AMR genes, the current knowledge on this “resistome” and the recent and upcoming advances in the molecular diagnostic approaches to unravel this reservoir.

Molecular clonality and antimicrobial resistance in Salmonella enterica serovars Enteritidis and Infantis from broilers in three Northern regions of Iran

BACKGROUND

Multidrug-resistant Salmonella strains are frequently encountered problems worldwide with considerable increased occurrences in recent years. The aim of this study was to investigate the occurrence and frequency of antimicrobial resistance and associated resistance genes in Salmonella isolates from broiler farms in different regions of Iran covering a time period of four years.

RESULTS

From 2007 to 2011, 36 Salmonella strains were isolated from broiler farms located in three northern provinces of Iran. The isolates were serotyped, antimicrobial susceptibility tested, and characterized for antimicrobial resistance genes associated to the phenotype. Pulsed-field gel electrophoresis (PFGE) was applied for comparison of genetic relatedness.Two serovars were detected among the isolates; Salmonella enterica serovar Infantis (75%) and S. Enteritidis (25%). Thirty-four (94%) of the isolates exhibited resistance to nalidixic acid and ciprofloxacin caused by a single mutation in the quinolone resistance-determining region (QRDR) of gyrA. For all strains this mutation occurred in the codon of Asp87 leading to a Asp87-Tyr, Asp87-Gly or Asp87-Asn substitutions. All S. Infantis (n = 27) were resistant to tetracycline, spectinomycin, streptomycin, and sulfamethoxazole and harbored the associated resistance genes; tetA, dfrA14, aadA1, and sulI together with class 1 integrons. The isolates revealed highly similar PFGE patterns indicating clonal relatedness across different geographical locations.

CONCLUSION

The data provided fundamental information applicable when launching future control programs for broilers in Iran with the aim to conserve the effectiveness of important antimicrobials for treatment in humans.

Role of efflux pumps in the antibiotic resistance of bacteria embedded in a biofilm

Biofilms are complex microbial associations anchored to abiotic or biotic surfaces, embedded in extracellular matrix produced by the biofilms themselves where they interact with each other and the environment. One of the main properties of biofilms is their capacity to be more resistant to antimicrobial agents than planktonic cells. Efflux pumps have been reported as one of the mechanisms responsible for the antimicrobial resistance in biofilm structures. Evidence of the role of efflux pump in biofilm resistance has been found in several microorganisms such as Pseudomonas aeruginosa, Escherichia coli and Candida albicans. However, in spite of the studies on the importance of efflux pumps in biofilm growth and about their relevance in antimicrobial resistance forming biofilm, the exact role of these efflux systems has not been determined as yet.

Tracking Change: A Look at the Ecological Footprint of Antibiotics and Antimicrobial Resistance

Among the class of pollutants considered as 'emerging contaminants', antibiotic compounds including drugs used in medical therapy, biocides and disinfectants merit special consideration because their bioactivity in the environment is the result of their functional design. Antibiotics can alter the structure and function of microbial communities in the receiving environment and facilitate the development and spread of resistance in critical species of bacteria including pathogens. Methanogenesis, nitrogen transformation and sulphate reduction are among the key ecosystem processes performed by bacteria in nature that can also be affected by the impacts of environmental contamination by antibiotics. Together, the effects of the development of resistance in bacteria involved in maintaining overall ecosystem health and the development of resistance in human, animal and fish pathogens, make serious contributions to the risks associated with environmental pollution by antibiotics. In this brief review, we discuss the multiple impacts on human and ecosystem health of environmental contamination by antibiotic compounds.

Serotypes, genotypes and antimicrobial resistance patterns of human diarrhoeagenic Escherichia coli isolates circulating in southeastern China

Diarrhoeagenic Escherichia coli (DEC) infection is a major health problem in developing countries. The prevalence and characteristics of DEC have not been thoroughly investigated in China. Consecutive faecal specimens from outpatients with acute diarrhoea in nine sentinel hospitals in southeastern China were collected from July 2009 to June 2011. Bacterial and viral pathogens were detected by culture and RT-PCR, respectively. DEC isolates were further classified into five pathotypes using multiplex PCR. The O/H serotypes, sequence types (STs) and antimicrobial susceptibility profiles of the DEC isolates were determined. A total of 2466 faecal specimens were collected, from which 347 (14.1%) DEC isolates were isolated. DEC was the dominant bacterial pathogen detected. The DEC isolates included 217 EAEC, 62 ETEC, 52 EPEC, 14 STEC, one EIEC and one EAEC/ETEC. O45 (6.6%) was the predominant serotype. Genotypic analysis revealed that the major genotype was ST complex 10 (87, 25.6%). Isolates belonging to the serogroups or genotypes of O6, O25, O159, ST48, ST218, ST94 and ST1491 were highly susceptible to the majority of antimicrobials. In contrast, isolates belonging to O45, O15, O1, O169, ST38, ST226, ST69, ST31, ST93, ST394 and ST648 were highly resistant to the majority of antimicrobials. DEC accounted for the majority of bacterial pathogens causing acute diarrhoea in southeastern China, and it is therefore necessary to test for all DEC, not only the EHEC O157:H7. Some serogroups or genotypes of DEC were highly resistant to the majority of antimicrobials. DEC surveillance should be emphasized.

Tracing subsequent dissemination of a cluster of gonococcal infections caused by an ST1407-related clone harbouring mosaic penA alleles in Taiwan

OBJECTIVES

Successful clones of Neisseria gonorrhoeae multiantigen sequence typing sequence type (ST) 1407 and ST1407-related genotypes have been reported to cause cefixime and ceftriaxone treatment failure in many countries. We characterized the 47 isolates of a strain cluster of ST4378, a genotype that differs in the porB sequence by only one nucleotide from ST1407, in Taiwan during April 2006 to June 2012.

METHODS

We identified 47 ST4378 isolates among our 2357 total isolates from the Gonococci-National Isolate Collection for Epidemiology. The corresponding patients' medical records were collected. The 47 isolates were further typed by multilocus sequence typing. Genes involved in β-lactam (ponA), quinolone (gyrA and parC) and multidrug (mtrR, porB1b and pilQ) resistance were sequenced. Antimicrobial susceptibility was determined by the disc diffusion test and Etest.

RESULTS

Cefixime MICs for the 47 isolates ranged from 0.016 to 0.19 mg/L and ceftriaxone MICs ranged from 0.012 to 0.094 mg/L. Forty-six of the 47 isolates had a mosaic penA allele type XXXIV and one had a new allele type XL, which appeared to be a recombinant of mosaic penA type XXXIV and non-mosaic penA type II. All of the isolates harboured nearly identical polymorphism in the ponA, gyrA, parC, mtrR, porB1b and pilQ genes. Among the 33 patients with known medical records, 25 (76%) were men who have sex with men (MSM), 3 (9%) were bisexual and 5 (15%) were heterosexual. Fourteen (42%) of the 33 patients had HIV, 8 (24%) had syphilis and 7 (21%) had both infections.

CONCLUSIONS

This is the first report of a cluster of ST1407-related strains in Taiwan. ST4378 is a genotype that may develop to cause third-generation cephalosporin treatment failures. Our results showed that ST4378 strains primarily transmitted in a high-risk MSM/bisexual network. The potential of these strains to become untreatable and spread to other low-risk sexual networks should be closely monitored.

Effect of Antimicrobial Exposure on AcrAB Expression in Salmonella enterica Subspecies enterica Serovar Choleraesuis

Understanding the impact of antimicrobial use on the emergence of resistant bacteria is imperative to prevent its emergence. For instance, activation of the AcrAB efflux pumps is responsible for the emergence of antimicrobial-resistant Salmonella strains. Here, we examined the expression levels of acrB and its multiple regulator genes (RamA, SoxS, MarA, and Rob) in 17 field isolates of S. Choleraesuis by using quantitative PCR methods. The expression of acrB increased in eight of the field isolates (P < 0.05). The expression of acrB was associated with that of ramA in one isolate, soxS in one isolate, and both these genes in six isolates. Thereafter, to examine the effect of selected antimicrobials (enrofloxacin, ampicillin, oxytetracycline, kanamycin, and spectinomycin) on the expression of acrB and its regulator genes, mutants derived from five isolates of S. Choleraesuis were selected by culture on antimicrobial-containing plates. The expression of acrB and ramA was higher in the mutants selected using enrofloxacin (3.3–6.3- and 24.5–37.7-fold, respectively), ampicillin (1.8–7.7- and 16.1–55.9-fold, respectively), oxytetracycline (1.7–3.3- and 3.2–31.1-fold, respectively), and kanamycin (1.6–2.2- and 5.6–26.4-fold, respectively), which are AcrAB substrates, than in each of the parental strains (P < 0.05). In contrast, in AcrAB substrate-selected mutants, the expression of soxS, marA, and rob remained similar to that in parental strains. Of the four antimicrobials, the level of ramA expression was significantly higher in the enrofloxacin- and ampicillin-selected mutants than in the oxytetracycline- and kanamycin-selected mutants (P < 0.05), whereas the expression levels of acrB and multiple regulator genes in spectinomycin-selected mutants were similar to those in each parental strain. These data suggest that exposure to antimicrobials that are AcrAB substrates enhance the activation of the AcrAB efflux pump via RamA, but not via SoxS, MarA, or Rob in S. Choleraesuis.

Mass distribution of azithromycin for trachoma control is associated with increased risk of azithromycin-resistant Streptococcus pneumoniae carriage in young children 6 months after treatment

BACKGROUND

Emerging evidence suggests that the mass distribution of azithromycin for trachoma control (MDA) may increase circulation of macrolide resistance in bacteria associated with severe pediatric infections in treated communities.

METHODS

We examined the effect of MDA on nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae among 1015 young children living in rural Tanzania. MDA with a single dose of oral azithromycin was provided in 4 of 8 communities where trachoma prevalence was ≥10%. Isolates were tested for susceptibility to azithromycin (AZM) and commonly used antibiotics by disk diffusion and Etest. We calculated the proportion of antibiotic-resistant S. pneumoniae carriage at baseline and again 1, 3, and 6 months after treatment, and at comparable intervals in the untreated villages.

RESULTS

The proportion of AZM-resistant isolates was similar between groups at baseline (MDA: 35.8% vs non-MDA: 35.4%), however, this proportion was greater in the MDA group in all subsequent surveys. At 6 months, the percentage of AZM-resistant isolates was significantly higher in the MDA group (81.9% vs 46.9%, P < .001). The odds of AZM-resistant carriage was 5-fold greater in the MDA group (odds ratio, 4.95 [95% confidence interval, 3.23-7.61]). The proportion of isolates clinically resistant to AZM (minimum inhibitory concentration ≥16 µg/mL) was also significantly greater in the MDA group at 6 months (35.3% vs 12.4%, P < .006).

CONCLUSIONS

Mass distribution of a single dose of oral azithromycin for trachoma was associated with increased circulation of macrolide-resistant S. pneumoniae carriage among young children in the 6 months following treatment. It is crucial that changes in antibiotic resistance patterns and their clinical significance in the treatment of severe pediatric infections be assessed in future MDA trials.

Foodborne urinary tract infections: a new paradigm for antimicrobial-resistant foodborne illness

Urinary tract infections (UTIs) are among the most common bacterial infections worldwide. Disproportionately affecting women, UTIs exact a substantial public burden each year in terms of direct medical expenses, decreased quality of life, and lost productivity. Increasing antimicrobial resistance among strains of extraintestinal pathogenic Escherichia coli challenges successful treatment of UTIs. Community-acquired UTIs were long considered sporadic infections, typically caused by the patients' native gastrointestinal microbiota; however, the recent recognition of UTI outbreaks with probable foodborne origins has shifted our understanding of UTI epidemiology. Along with this paradigm shift come new opportunities to disrupt the infection process and possibly quell increasing resistance, including the elimination of non-therapeutic antimicrobial use in food-animal production.

The bacteriological safety and antimicrobial susceptibility of bacteria isolated from street-vended white lupin (Lupinus albus) in Bahir Dar, Ethiopia

BACKGROUND

Whereas street vended foods are readily available sources of meals for many people across the world, the microbial safety of such food is always uncertain. In developing countries the major sources of food-borne illnesses are street vended foods. The aim of this study was thus to assess the prevalence and antibiogram of bacteria from white lupin in Bahir Dar Town.

METHODS

A total of 40 samples were processed for detection of indicator bacteria and pathogens from December, 2011 to February, 2012 using standard bacteriological techniques. Antimicrobial susceptibility test was performed using the Kirby-Bauer disk diffusion method.

RESULTS

The total coliform counts were 954.2±385 and 756.2±447.3 at the surface and the core of white lupin, respectively. On the other hand, the fecal coliform counts were 880.9±396.6 and 662.1±461.9 at surface and the core, respectively. There was a statistically significant difference in total colifoms and fecal coliform counts between the surface and core of white lupin (p <0.05). Escherichia coli 29 (72.5%), Salmonella spp. 23 (57.5%) and Shigella spp. 8 (20%) were the pathogens isolated. Most bacterial isolates were resistant to tetracycline, cotriamoxazole and erythromycin whereas many of them were sensitive to chloramphenicol, nalidixic acid, gentamicin and ciprofloxacin. The overall multiple antimicrobial resistances rate was 75%.

CONCLUSION

This study revealed contamination of white lupin and a potential health to consumers, and the bacteria isolated showed high rates of multiple drug resistance. Surveillance of antimicrobial resistance should be done on food borne pathogens. In addition, further studies should be conducted on the bacteriological quality of waters used for soaking white lupin.

A retrospective comparative study of 2-drug oral and intramuscular cephalosporin treatment regimens for pharyngeal gonorrhea

BACKGROUND

The Centers for Disease Control and Prevention guidelines for pharyngeal gonorrhea treatment recommend dual therapy with intramuscular ceftriaxone and either azithromycin or doxycycline. Few clinical data exist to support this recommendation.

METHODS

We conducted a retrospective analysis of patients diagnosed with pharyngeal gonorrhea during 1993-2011, at a sexually transmitted disease clinic in Seattle, Washington, and compared the proportion of repeat positive tests for pharyngeal gonorrhea 7-180 days following treatment among persons receiving different drug regimens. Associations of treatment regimens were assessed using relative risks through Poisson regression models with log link and robust standard errors.

RESULTS

A total of 1440 cases of pharyngeal gonorrhea were diagnosed during the study period, 25% of which (n = 360) underwent retesting. Among retested patients, the risk of repeat positive test was lowest among persons receiving an oral cephalosporin and azithromycin (7%, reference group), and highest among those receiving an oral cephalosporin alone (30%; relative risk [RR], 3.98; 95% confidence interval [CI], 1.70-9.36) or in combination with doxycycline (33%; RR, 4.18; 95% CI, 1.64-10.7). The risk of repeat test positivity did not significantly differ between persons treated with an oral cephalosporin and azithromycin and those treated with ceftriaxone alone (9.1%; RR, 0.81; 95% CI, .18-3.60) or ceftriaxone combined with azithromycin or doxycycline (11.3%; RR, 1.20; 95% CI, .43-3.33).

CONCLUSIONS

In this retrospective study, dual therapy with an oral third-generation cephalosporin and azithromycin was comparable to ceftriaxone-based regimens in the treatment of pharyngeal gonorrhea. Combination oral therapy with doxycycline was associated with an elevated risk of persistent or recurrent infection.

Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from India, Pakistan and Bhutan in 2007-2011

BACKGROUND

Knowledge on antimicrobial drug resistance and genetic characteristics of Neisseria gonorrhoeae isolates circulating in India, Pakistan, and Bhutan is sorely lacking. In this paper, we describe the prevalence of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates from India, Pakistan, and Bhutan in 2007-2011.

METHODS

Antimicrobial susceptibility and β-lactamase production were tested for 65 N. gonorrhoeae isolates from India (n=40), Pakistan (n=18) and Bhutan (n=7) using Etest methodology (eight antimicrobials) and nitrocefin solution, respectively. Resistance determinants, i.e. penA, mtrR, porB1b, gyrA, and parC, were sequenced. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed for molecular epidemiology.

RESULTS

The highest resistance level was observed for ciprofloxacin (94%), followed by penicillin G (68%), erythromycin (62%), tetracycline (55%), and azithromycin (7.7%). All the isolates were susceptible to ceftriaxone, cefixime, and spectinomycin. Thirty-four (52%) of the isolates were producing β-lactamase. No penA mosaic alleles or A501-altered alleles of penicillin-binding protein 2 were identified. Forty-nine NG-MAST STs were identified, of which 42 STs have not been previously described worldwide.

CONCLUSIONS

Based on this study, ceftriaxone, cefixime, and spectinomycin can be used as an empirical first-line therapy for gonorrhoea in India, Pakistan, and Bhutan, whereas ciprofloxacin, penicillin G, tetracycline, erythromycin, and azithromycin should not be. It is imperative to strengthen the laboratory infrastructure in this region, as well as to expand the phenotypic and genetic surveillance of antimicrobial resistance, emergence of new resistance, particularly, to extended-spectrum cephalosporins, and molecular epidemiology.

Access to antibiotics: a safety and equity challenge for the next decade

Bacterial resistance to antibiotics is increasing worldwide in healthcare settings and in the community. Some microbial pathogens have become resistant to multiple antibiotics, if not all presently available, thus severely compromising treatment success and contributing to enhanced morbidity, mortality, and resource use. The major driver of resistance is misuse of antibiotics in both human and non-human medicine. Both enhanced access and restricted use in many parts of the world is mandatory. There is an urgent need for an international, integrated, multi-level action to preserve antibiotics in the armamentarium of the 21st century and address the global issue of antimicrobial resistance.

Antimicrobial stewardship: a review of prospective audit and feedback systems and an objective evaluation of outcomes

Antimicrobial stewardship is an emerging field currently defined by a series of strategies and interventions aimed toward improving appropriate prescription of antibiotics in humans in all healthcare settings. The ultimate goal is the preservation of current and future antibiotics against the threat of antimicrobial resistance, although improving patient safety and reducing healthcare costs are important concurrent aims. Prospective audit and feedback interventions are probably the most widely practiced of all antimicrobial stewardship strategies. Although labor-intensive, they are more easily accepted by physicians compared with formulary restriction and preauthorization strategies and have a higher potential for educational opportunities. Objective evaluation of antimicrobial stewardship is critical for determining the success of such programs. Nonetheless, there is controversy over which outcomes to measure and there is a pressing need for novel study designs that can objectively assess antimicrobial stewardship interventions despite the limitations inherent in the structure of most such programs.

The emerging problem of linezolid-resistant Staphylococcus

The oxazolidinone antibiotic linezolid has demonstrated potent antimicrobial activity against Gram-positive bacterial pathogens, including methicillin-resistant staphylococci. This article systematically reviews the published literature for reports of linezolid-resistant Staphylococcus (LRS) infections to identify epidemiological, microbiological and clinical features for these infections. Linezolid remains active against >98% of Staphylococcus, with resistance identified in 0.05% of Staphylococcus aureus and 1.4% of coagulase-negative Staphylococcus (CoNS). In all reported cases, patients were treated with linezolid prior to isolation of LRS, with mean times of 20.0 ± 47.0 months for S. aureus and 11.0 ± 8.0 days for CoNS. The most common mechanisms for linezolid resistance were mutation (G2576T) to the 23S rRNA (63.5% of LRSA and 60.2% of LRCoNS) or the presence of a transmissible cfr ribosomal methyltransferase (54.5% of LRSA and 15.9% of LRCoNS). The emergence of linezolid resistance in Staphylococcus poses significant challenges to the clinical treatment of infections caused by these organisms, and in particular CoNS.

Antimicrobial and analgesic prescribing patterns for acute otitis externa, 2004-2010

OBJECTIVE

Acute otitis externa (AOE) is a common but preventable ear condition. Clinical guidelines issued in 2006 recommended topical treatments for uncomplicated AOE, but systemic antimicrobials appear to be commonly prescribed. The objective of this analysis was to describe pre- and postguideline prescribing patterns by clinician specialty and antimicrobial type and assess trends over time.

STUDY DESIGN

Retrospective longitudinal analysis of a large insurance database.

SETTING

Outpatient departments in the United States.

METHODS

Initial outpatient visits in 2004 to 2010 for AOE (excluding visits with complicating conditions) were extracted from an insurance database. Prescription drug claims were linked and categorized by clinician specialty and antimicrobial type.

RESULTS

The analysis included 907,261 initial outpatient visits. Use of systemic antimicrobials declined by 4.9% (95% confidence interval [CI], 4.1%, 5.7%) from 36.5% of initial visits in 2004 to 32.1% in 2010. Use of systemic antimicrobials varied by specialty. Systemic antimicrobials were prescribed in 47.1% of 2010 emergency department (ED) visits (-6.9% from 2004, 95% CI -12.3, -1.5), 25.9% of otolaryngologist visits (-1.6%, 95% CI -5.6, 2.4), and 20.4% of pediatrician visits (-6.6%, 95% CI -8.8, -4.4). Penicillins were prescribed most frequently (42.3% of systemic prescriptions in 2010), followed by cephalosporins (19.8%), erythromycin/macrolides (17.4%), and quinolones (11.1%). Opioids were prescribed in 26.4% of ED visits and 9% of outpatient visits.

CONCLUSIONS

Use of systemic antimicrobials declined over time, but one-third of 2010 visits resulted in systemic antimicrobials, despite exclusion of visits with complicating factors. Use of systemic antimicrobials varied by specialty. Further educational efforts and outreach to other specialties might be warranted.

Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.)

BACKGROUND

Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown.

RESULTS

Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym) that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins.

CONCLUSIONS

Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.

Feeding untreated and pasteurized waste milk and bulk milk to calves: effects on calf performance, health status and antibiotic resistance of faecal bacteria

Non-saleable milk (waste milk, WM) is contaminated with an undefined spectrum of potentially harmful pathogens and antimicrobial residues. The objective of this study was to determine the impact of feeding bulk milk (BM) or WM - both pasteurized or not - on calf performance, health and the antibiotic resistance of specific faecal bacteria. A total of 114 calves from a large-scale dairy were housed outdoors in individual hutches and were randomly assigned to one of four feeding groups. The calves were fed either WM, pasteurized WM (pWM), BM or pasteurized BM (pBM) from day 3 to 56 of life. Milk samples taken from the pasteurizer and calves' nipple buckets were investigated at regular intervals for total plate count and counts of thermoduric bacteria, coliforms and mastitis pathogens. Faecal samples were taken on days 2, 14, 28 and 56 of life from randomly selected calves of the WM, pWM and BM groups (each N = 8-9) and processed to obtain from each sample preferably two isolates of Escherichia (E.) coli and Enterococcus spp. respectively. Isolates were tested for their antimicrobial susceptibility to 25 antimicrobial agents by broth microdilution. Daily weight gain, milk and calf starter intake and health parameters did not differ significantly between the calves of the four feeding groups. The proportion of resistant E. coli isolates was significantly higher in calves fed WM and in calves fed pWM (most pronounced for cephalosporins) than in calves receiving BM. No differences in resistance were found for Enterococus spp. Thus, the concerns for selecting resistant faecal bacteria by feeding WM seem to be justified. Nonetheless, pasteurized WM of cows not treated with antimicrobials represents an acceptable feed for young calves.

Emergence of multidrug-resistant, extensively drug-resistant and untreatable gonorrhea

The new superbug Neisseria gonorrhoeae has retained resistance to antimicrobials previously recommended for first-line treatment and has now demonstrated its capacity to develop resistance to the extended-spectrum cephalosporin, ceftriaxone, the last remaining option for first-line empiric treatment of gonorrhea. An era of untreatable gonorrhea may be approaching, which represents an exceedingly serious public health problem. Herein, we review the evolution, origin and spread of antimicrobial resistance and resistance determinants (with a focus on extended-spectrum cephalosporins) in N. gonorrhoeae, detail the current situation regarding verified treatment failures with extended-spectrum cephalosporins and future treatment options, and highlight essential actions to meet the large public health challenge that arises with the possible emergence of untreatable gonorrhea. Essential actions include: implementing action/response plans globally and nationally; enhancing surveillance of gonococcal antimicrobial resistance, treatment failures and antimicrobial use/misuse; and improving prevention, early diagnosis and treatment of gonorrhea. Novel treatment strategies, antimicrobials (or other compounds) and, ideally, a vaccine must be developed.

Multidrug Efflux Systems in Helicobacter cinaedi

Helicobacter cinaedi causes infections, such as bacteremia, diarrhea and cellulitis in mainly immunocompromised patients. This pathogen is often problematic to analyze, and insufficient information is available, because it grows slowly and poorly in subculture under a microaerobic atmosphere. The first-choice therapy to eradicate H. cinaedi is antimicrobial chemotherapy; however, its use is linked to the development of resistance. Although we need to understand the antimicrobial resistance mechanisms of H. cinaedi, unfortunately, sufficient genetic tools for H. cinaedi have not yet been developed. In July 2012, the complete sequence of H. cinaedi strain PAGU 611, isolated from a case of human bacteremia, was announced. This strain possesses multidrug efflux systems, intrinsic antimicrobial resistance mechanisms and typical mutations in gyrA and the 23S rRNA gene, which are involved in acquired resistance to fluoroquinolones and macrolides, respectively. Here, we compare the organization and properties of the efflux systems of H. cinaedi with the multidrug efflux systems identified in other bacteria.

Identification and characterization of a novel incompatibility group X3 plasmid carrying bla NDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China

The New Delhi metallo-β-lactamase (NDM-1) is one of the most important resistance traits in Enterobacteriaceae. We characterized nine bla_NDM-1 producing Enterobacteriaceae recovered from seven patients who have recently travelled or been treated in India (n=1) or mainland China (n=6) during December 2010–May 2012. All the China-linked patients had no links to the Indian subcontinent. The bla_NDM-1 carrying plasmids belonged to the novel IncX3 (∼50 kb, in seven isolates including two Escherichia coli, two Klebsiella pneumoniae, one Citrobacter freundii, one Enterobacter aerogenes and one E. cloacae), IncA/C2 (∼140 kb, in one E. coli) or FII-F1B groups (∼110 kb, in one E. coli). Restriction fragment length polymorphism analysis of the seven IncX3 plasmids revealed identical pattern in six and two bands difference in the remaining one. The IncX3 plasmids carrying bla_NDM-1 were epidemiologically linked to Guangzhou (n=1), Hunan (n=4), Haifeng (n=1) and Dongguan (n=1) in mainland China. Complete sequencing of the IncX3 plasmid pNDM-HN380 revealed that it was 54 035 bp long and encoded 52 open reading frames. The bla_NDM-1 gene was found in a transposon-like structure flanked by ISAba125 and IS26, inserted into the plasmid genetic load region. The sequences of the bla_NDM-1 containing module within the two IS elements were identical to those previously described for bla_NDM-1-positive Tn125 in the plasmids or chromosome of Acinetobacter isolates. In summary, this is the first description of IncX3 plasmids carrying bla_NDM-1. The findings indicate the worrisome involvement of an epidemic plasmid in the dissemination of NDM-1 in China.

Cefditoren: Comparative efficacy with other antimicrobials and risk factors for resistance in clinical isolates causing UTIs in outpatients

BACKGROUND

To investigate a possible role of Cefditoren, a recently marketed in Greece third-generation oral cephalosporin in urinary infections of outpatients.

METHODS

During a multicenter survey of Enterobacteriaceae causing UTIs in outpatients during 2005-2007, Cefditoren MICs were determined by agar dilution method in a randomly selected sample of uropathogens. Susceptibility against 18 other oral/parenteral antimicrobials was determined according to Clinical and Laboratory Standards Institute methodology.

RESULTS

A total of 563 isolates (330 Escherichia coli, 142 Proteus mirabilis and 91 Klebsiella spp) was studied; MIC50/MIC90 of Cefditoren was 0.25/0.5 mg/L respectively, with 97.1% of the isolates being inhibited at 1 mg/L. All 12 strains producing ESBLs or AmpC enzymes were resistant to cefditoren. Susceptibility rates (%) for amoxicillin/clavulanic acid, cefuroxime axetil, cefotaxime, ciprofloxacin, trimethoprim/sulfamethoxazole and fosfomycin were 93.1- 94.1- 96.8-93.1-71.9 and 92.8% respectively. Cefditoren MIC was significantly higher in nalidixic/ciprofloxacin non-susceptible strains; resistance to cefditoren was not associated with resistance to mecillinam, fosfomycin nitrofurantoin and aminoglycosides. Multivariate analysis demonstrated history of urinary infection in the last two weeks or three months as risk factors for cefditoren resistance.

CONCLUSIONS

Cefditoren exhibited enhanced in vitro activity against the most common uropathogens in the outpatient setting, representing an alternative oral treatment option in patients with risk factors for resistance to first-line antibiotics.

Invasive Bacterial Pathogens and their Antibiotic Susceptibility Patterns in Jimma University Specialized Hospital, Jimma, Southwest Ethiopia

Background

Presence of microorganisms in the circulating blood whether continuously or intermittently is a threat to every organ in the body. Approximately 200,000 cases of bacteraemia occur annually with mortality rates ranging from 20–50%. Early diagnosis and appropriate treatment of these infections can make the difference between life and death. The aim of the present study was to determine the bacterial flora of the blood stream infections and their antibiotic susceptibility pattern.

Methods

A cross sectional study was conducted on 260 adult febrile patients in Jimma University Specialized Hospital from 27 October 2009 to 26 March 2010. The positive blood cultures were examined and the organisms were identified as per standard procedures. Antimicrobial testing was performed for all isolates by disk diffusion techniques, according to Clinical Laboratory Standards Institute guide lines. The data was analyzed using SPSS for windows version 16 and Microsoft Office Excel.

Results

From the total of two hundred sixty blood specimens only 23(8.8%) were positive to seven different types of bacteria. The isolated bacteria were: Coagulase negative staphylococci 6(26.1%), S. aureus 5 (21.7%), S. pyogens 3 (13.0%), E. coli 4(17.4%), K. pneumoniae 3(13.0%), Salmonella spp. 1(4.3%), and Citrobacter spp. 1(4.3%). The isolates showed high rates of resistance to most antibiotics tested. The range of resistance for gram positive bacteria were 0% to 85.7%, and for gram negative from 0% to 100%. None of the isolates were resistance to ciprofloxacin and ceftriaxone.

Conclusion

Our study result showed the presence of invasive bacterial pathogens with high rate of resistance to most commonly used antibiotics used to treat bacterial infections. Therefore, timely investigation of bacterial flora of the blood stream infections and monitoring of their antibiotic resistance pattern plays an important role in reduction of the incidence of blood stream infections.

A 9-Year retrospective review of antibiotic cycling in a surgical intensive care unit

BACKGROUND

Six years after initiating a monthly antibiotic cycling protocol in the surgical intensive care unit (SICU), we retrospectively reviewed antibiogram-derived sensitivities of predominant gram-negative pathogens before and after antibiotic cycling. We also examined susceptibility patterns in the medical intensive care unit (MICU) where antibiotic cycling is not practiced.

MATERIALS AND METHODS

Antibiotic cycling protocol was implemented in the SICU starting in 2003, with monthly rotation of piperacillin/tazobactam, imipenem/cilastin, and ceftazidime. SICU antibiogram data from positive clinical cultures for years 2000 and 2002 were included in the pre-cycling period, and those from 2004 to 2009 in the cycling period.

RESULTS

Profiles of SICU pseudomonal isolates before (n = 116) and after (n = 205) implementing antibiotic cycling showed statistically significant improvements in susceptibility to ceftazidime (66% versus 81%; P = 0.003) and piperacillin/tazobactam (75% versus 85%; P = 0.021), while susceptibility to imipenem remained unaltered (70% in each case; P = 0.989). Susceptibility of E. coli isolates to piperacillin/tazobactam improved significantly (46% versus 83%; P < 0.0005), trend analysis showing this improvement to persist over the study period (P = 0.025). Similar findings were not observed in the MICU. Review of 2004-2009 antibiotic prescription practices showed monthly heterogeneity in the SICU, and a 2-fold higher prescribing of piperacillin/tazobactam in the MICU (P < 0.0001).

CONCLUSIONS

Six years into antibiotic cycling, we found either steady or improved susceptibilities of clinically relevant gram-negative organisms in the SICU. How much of this effect is from cycling is unknown, but the antibiotic heterogeneity provided by this practice justifies its ongoing use.

Characterization of enterotoxigenic E. coli (ETEC), Shiga-toxin producing E. coli (STEC) and necrotoxigenic E. coli (NTEC) isolated from diarrhoeic Mediterranean water buffalo calves (Bubalus bubalis)

Two hundred and twenty Escherichia coli isolates from 314 Mediterranean water buffalo calves less than 4 weeks old affected by severe diarrhoea with a lethal outcome were characterized for the presence of the virulence factors LT, ST, Stx1, Stx2, haemolysins, intimin, CNF1, CNF2, CDT-I, CDT-II, CDT-III, CDT-IV, and F17-related fimbriae (F17a, F17b, F17c, F17d). The prevalence of ETEC, STEC and NTEC were 1.8%, 6.8% and 20.9%, respectively. The ETEC isolates were all LT-positive and ST-negative. The STEC isolates were all Stx and intimin-positive, with Stx1 (80%) more frequent than Stx2 (27%). The NTEC isolates were all CNF and Hly-positive, with CNF2 (83%) more frequent than CNF1 (22%). Susceptibility assays to 11 antimicrobials displayed high rates of resistance (>30%) to antimicrobials tested. These data show that the most prevalent strains in diarrhoeic water buffalo calves were NTEC, mostly CNF2 and HlyA-positive, with strong associations CNF2/CDT-III and CNF2/F17c.

Extended-spectrum beta-lactamase-producing bacteria in a tertiary care hospital in Madrid: epidemiology, risk factors and antimicrobial susceptibility patterns

INTRODUCTION

Extended-spectrum beta-lactamase (ESBL) producing bacteria have been increasingly reported as causal agents of nosocomial infection worldwide. Resistance patterns vary internationally, and even locally, from one institution to the other. We investigated the clinical isolates positive for ESBL-producing bacteria in our institution, a tertiary care hospital in Madrid (Spain), during a 2-year period (2007-2008).

METHODS

Clinical and microbiological data were retrospectively reviewed. Two hundred and nineteen patients were included in the study.

RESULTS

Advanced age, diabetes, use of catheters, previous hospitalization and previous antibiotic treatment were some of the risk factors found among patients. Escherichia coli was the most frequent isolate, and urinary tract the most common site of isolation. Internal Medicine, Intensive Care Unit (ICU) and General Surgery presented the highest number of isolates. There were no outbreaks during the study period. Antibiotic patterns showed high resistance rates to quinolones in all isolates. There was 100% sensitivity to carbapenems.

CONCLUSION

Carbapenems continue to be the treatment of choice for ESBL-producing bacteria. Infection control measures are of great importance to avoid the spread of these nosocomial infections.

Attitudes of primary care physicians to the prescribing of antibiotics and antimicrobial resistance: a qualitative study from Spain

BACKGROUND AND OBJECTIVE

Resistance to antibiotics is a public health threat. A number of studies confirm the relationship between antibiotic use and the resistance rate. As a whole, physicians represent a large proportion of the health professionals involved in the use of this therapeutic group. Our study therefore sought to ascertain the opinions and attitudes of GPs in Spain with respect to antibiotics and resistance.

METHODS

We used the focus group (FG) method, with each group comprising 4-12 primary care physicians and a moderator. Based on a previous systematic review, we drew up an agenda to be followed during the holding of the sessions. Group proceedings were recorded and the transcriptions then analysed separately by two researchers.

RESULTS

Five FGs were formed, including a total of 33 physicians. The factors/attitudes that influenced the prescribing of antibiotics by GPs were fear, complacency, insufficient knowledge and external responsibility of the pharmaceutical industry, patients and over-the-counter antibiotics. The groups felt that antibiotic resistance was not a problem at a community level.

CONCLUSIONS

Identification of attitudes/knowledge related with inappropriate antibiotic prescribing will enable specific interventions to be designed, with the aim of targeting these shortcomings to improve antibiotic use and help reduce resistance.

Heavy metal tolerance (Cr, Ag AND Hg) in bacteria isolated from sewage

Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerant Bacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.

The Acinetobacter baumannii Oxymoron: Commensal Hospital Dweller Turned Pan-Drug-Resistant Menace

During the past few decades Acinetobacter baumannii has evolved from being a commensal dweller of health-care facilities to constitute one of the most annoying pathogens responsible for hospitalary outbreaks and it is currently considered one of the most important nosocomial pathogens. In a prevalence study of infections in intensive care units conducted among 75 countries of the five continents, this microorganism was found to be the fifth most common pathogen. Two main features contribute to the success of A. baumannii: (i) A. baumannii exhibits an outstanding ability to accumulate a great variety of resistance mechanisms acquired by different mechanisms, either mutations or acquisition of genetic elements such as plasmids, integrons, transposons, or resistant islands, making this microorganism multi- or pan-drug-resistant and (ii) The ability to survive in the environment during prolonged periods of time which, combined with its innate resistance to desiccation and disinfectants, makes A. baumannii almost impossible to eradicate from the clinical setting. In addition, its ability to produce biofilm greatly contributes to both persistence and resistance. In this review, the pathogenesis of the infections caused by this microorganism as well as the molecular bases of antibacterial resistance and clinical aspects such as treatment and potential future therapeutic strategies are discussed in depth.

A longitudinal study of antimicrobial resistant faecal bacteria in sediments collected from a hospital wastewater system

Objective

The objective with this study was to determine and follow antimicrobial resistance in faecal bacteria over time in hospital wastewater pipe sediment. A further aim was to determine bacterial growth rates of sensitive, intermediate and resistant intestinal enterococci in different ciprofloxacin concentrations as a measure of bacterial fitness.

Methods

A system enabling the collection of settled particles over time was installed at Kalmar County Hospital. Samples were collected bi-monthly for a 14-month period. Coliform bacteria and enterococci were isolated from the sediment with standard methods and investigated for resistance to ciprofloxacin (CIP), imipenem (IMI), trimetroprim-sulfamethoxazole (TS), ampicillin (AMP) and vancomycin (VAN) by the disc diffusion method. Resistant isolates were further typed with the PhenePlateTM system. Growth assessments were performed with an automated spectrophotometer.

Results

The rate of intestinal enterococci resistance was <0.6, 1.3, 1.9 and 13% to VAN, IMI, AMP and CIP respectively. Coliform resistance frequencies were 1.1, 2.2 and 2.2% to CIP, IMI and TS respectively. At two sampling occasions, significantly higher rates of ciprofloxacin resistant enterococci were found and the establishment of a resistant clone in the sewer was indicated by the PhP-analysis. Ciprofloxacin resistant intestinal enterococci had a significantly longer lag-phase time than sensitive isolates, but from 500 µg ml⁻¹ (half MIC) resistant isolates had a competitive advantage in terms of significantly faster generation time.

Discussion

Despite high concentration of antimicrobials in the sediment, resistance frequencies were generally low. This can depend on limited growth possibilities for faecal bacteria. However, the establishment of a resistant clone shows that hospital sewers can serve as a reservoir for antibiotic resistant bacteria.

Identification and antimicrobial resistance of campylobacter species isolated from animal sources

Background:Campylobacter spp. are together with Salmonella spp. the leading causes of human bacterial gastroenteritis worldwide. The most commonly isolated species in humans are Campylobacter jejuni and C. coli. The isolation, identification, and antimicrobial resistance of Campylobacter spp. from poultry and raw meat from slaughterhouses, has been investigated for the first time in Greece. During the period from August 2005 to November 2008 a total of 1080 samples were collected: (a) 830 fecal samples from five poultry farms, (b) 150 cecal samples from chicken carcasses in a slaughterhouse, and (c) 100 fecal samples from one pig farm near the region of Attica. The identification of the isolates was performed with conventional (sodium hippurate hydrolysis and commercial identification system (Api CAMPY system, bioMerieux, France), as well as with and molecular methods based on 16S rRNA species specific gene amplification by PCR and subsequent sequence analysis of the PCR products. Results: Sixteen Campylobacter strains were isolated, all collected from the poultry farms. None of the strains was identified as C. jejuni. Antimicrobial susceptibility to six antimicrobials was performed and all the strains were susceptible to ciprofloxacin, amoxicillin–clavulanic acid, and gentamicin. Thirteen out of 14 C. coli were resistant to erythromycin and all C. coli strains were resistant to ampicillin. Conclusion: Our results emphasize the need for a surveillance and monitoring system with respect to the prevalence and antimicrobial resistance of Campylobacter in poultry, as well as for the use of antimicrobials in veterinary medicine in Greece.

Resident Cats in Small Animal Veterinary Hospitals Carry Multi-Drug Resistant Enterococci and are Likely Involved in Cross-Contamination of the Hospital Environment

In the USA, small animal veterinary hospitals (SAVHs) commonly keep resident cats living permanently as pets within their facilities. Previously, multi-drug resistant (MDR) enterococci were found as a contaminant of multiple surfaces within such veterinary hospitals, and nosocomial infections are a concern. The objectives of this study were to determine whether resident cats carry MDR enterococci and to compare the feline isolates genotypically to those obtained from SAVH surfaces in a previous study. Enterococcal strains (n = 180) were isolated from the feces of six healthy resident cats from different SAVHs. The concentration of enterococci ranged from 1.1 × 10⁵ to 6.0 × 10⁸ CFU g⁻¹ of feces, and the population comprised Enterococcus hirae (38.3 ± 18.6%), E. faecium (35.0 ± 14.3%), E. faecalis (23.9 ± 11.0%), and E. avium (2.8 ± 2.2%). Testing of phenotypic resistance to 14 antimicrobial agents revealed multi-drug resistance (≥3 antimicrobials) in 48.9% of all enterococcal isolates with most frequent resistance to tetracycline (75.0%), erythromycin (50.0%), and rifampicin (36.1%). Vancomycin resistant E. faecalis (3.9%) with vanB not horizontally transferable in in vitro conjugation assays were detected from one cat. Genotyping with pulsed-field gel electrophoresis demonstrated a host-specific clonal population of MDR E. faecalis and E. faecium. Importantly, several feline isolates were genotypically identical or closely related to isolates from surfaces of cage door, thermometer, and stethoscope of the corresponding SAVHs. These data demonstrate that healthy resident cats at SAVHs carry MDR enterococci and likely contribute to contamination of the SAVH environment. Proper disposal and handling of fecal material and restricted movement of resident cats within the ward are recommended.

Extraintestinal Pathogenic Escherichia coli: A Combination of Virulence with Antibiotic Resistance

Escherichia coli represents an incredible versatile and diverse enterobacterial species and can be subdivided into the following; (i) intestinal non-pathogenic, commensal isolates. (ii) Intestinal pathogenic isolates and (iii) extraintestinal pathogenic E. coli or ExPEC isolates. The presence to several putative virulence genes has been positively linked with the pathogenicity of ExPEC. E. coli remains one of the most frequent causes of nosocomial and community-acquired bacterial infections including urinary tract infections, enteric infections, and systemic infections in humans. ExPEC has emerged in 2000s as an important player in the resistance to antibiotics including the cephalosporins and fluoroquinolones. Most importantly among ExPEC is the increasing recognition of isolates producing “newer β-lactamases” that consists of plasmid-mediated AmpC β-lactamases (e.g., CMY), extended-spectrum β-lactamases (e.g., CTX-M), and carbapenemases (e.g., NDM). This review will highlight aspects of virulence associated with ExPEC, provide a brief overview of plasmid-mediated resistance to β-lactams including the characteristics of the successful international sequence types such as ST38, ST131, ST405, and ST648 among ExPEC.

Change of antimicrobial susceptibility among Escherichia coli strains isolated from female patients with community-onset acute pyelonephritis

PURPOSE

There is a concern on which antimicrobials are appropriate as empirical agents for community-onset acute pyelonephritis (APN) in regions where the fluoroquinolone resistance rate is high, such as in Korea.

MATERIALS AND METHODS

Three hundred and two strains of E. coli in 2001-2002 and 349 strains in 2008-2009 were isolated from the urine cultures of female adult APN patients, and the antimicrobial susceptibility was compared according to each study period. All the patients were classified as uncomplicated or complicated APN, and a subgroup analysis was done thereafter.

RESULTS

The E. coli strains isolated in 2008-2009 showed improved susceptibility to trimethoprim-sulfamethoxazole compared to those isolated in 2001-2002. However, the third generation cephalosporin and gentamicin susceptibility was worsened. Of the 232 isolates from the uncomplicated APN patients, there was no difference between the two different time periods. On the other hand, of the 419 isolates from the complicated APN patients, the susceptibility to third generation cephalosporin, gentamicin and ciprofloxacin was significantly worsened.

CONCLUSION

The antimicrobial susceptibility of E. coli changed over the study period, however, this change occurred mainly in the complicated APN patients. In Korea, ciprofloxacin is still useful as an empirical agent for uncomplicated APN patients, but this is not the case for patients with complicated APN because of high resistance rate to ciprofloxacin in these patients. For the complicated APN patients, the rate of resistance to ciprofloxacin is already more than 30%.

C4-alkylthiols with activity against Moraxella catarrhalis and Mycobacterium tuberculosis

Antimicrobial resistance represents a global threat to healthcare. The ability to adequately treat infectious diseases is increasingly under siege due to the emergence of drug-resistant microorganisms. New approaches to drug development are especially needed to target organisms that exhibit broad antibiotic resistance due to expression of β-lactamases which is the most common mechanism by which bacteria become resistant to β-lactam antibiotics. We designed and synthesized 20 novel monocyclic β-lactams with alkyl- and aryl-thio moieties at C4, and subsequently tested these for antibacterial activity. These compounds demonstrated intrinsic activity against serine β-lactamase producing Mycobacterium tuberculosis wild type strain (Mtb) and multiple (n=6) β-lactamase producing Moraxella catarrhalis clinical isolates.

Limiting the spread of highly resistant hospital-acquired microorganisms via critical care transfers: a simulation study

PURPOSE

Hospital-acquired infections with highly resistant organisms are an important problem among critically ill patients. Control of these organisms has largely focused within individual hospitals. We examine the extent to which transfers of critically ill patients could be a vector for the wide spread of highly resistant organisms, and compare the efficiency of different approaches to targeting infection control resources.

METHODS

We analyzed the network of interhospital transfers of intensive care unit patients in 2005 US Medicare data and 2004-2006 Pennsylvania all-payer data. We simulated the spread of highly resistant hospital-acquired infections by randomly choosing a single hospital to develop a highly resistant organism and following the spread of infection or colonization throughout the network under varying strategies of infection control and varying levels of infectivity.

RESULTS

Critical care transfers could spread a highly resistant organism between any two US hospitals in a median of 3 years. Hospitals varied substantially in their importance to limiting potential spread. Targeting resources to a small subset of hospitals on the basis of their position in the transfer network was 16 times more efficient than distributing infection control resources uniformly. Within any set of targeted hospitals, the best strategy for infection control heavily concentrated resources at a few particularly important hospitals, regardless of level of infectivity.

CONCLUSIONS

Critical care transfers provide a plausible vector for widespread dissemination of highly resistant hospital-acquired microorganisms. Infection control efforts can be made more efficient by selectively targeting hospitals most important for transmission.

Antimicrobial susceptibility of bacterial isolates from community acquired infections in Sub-Saharan Africa and Asian low and middle income countries

OBJECTIVE

Antimicrobial resistance has arisen across the globe in both nosocomial and community settings as a consequence of widespread antibiotic consumption. Poor availability of laboratory diagnosis means that resistance frequently goes unrecognised and may only be detected as clinical treatment failure. In this review, we provide an overview of the reported susceptibility of common community acquired bacterial pathogens in Sub-Saharan Africa and Asia to the antibiotics that are most widely used in these areas.

METHODS

We reviewed the literature for reports of the susceptibility of prevalent pathogens in the community in SSA and Asia to a range of commonly prescribed antibiotics. Inclusion criteria required that isolates were collected since 2004 and that they were obtained from either normally sterile sites or urine. The data were aggregated by region and by age group.

RESULTS

Eighty-three studies were identified since 2004 which reported the antimicrobial susceptibilities of common bacterial pathogens. Different methods were used to assess in-vitro susceptibility in the different studies. The quality of testing (evidenced by resistance profiles) also varied considerably. For Streptococcus pneumoniae and Neisseria meningitidis most drugs maintained relatively high efficacy, apart from co-trimoxazole to which there were high levels of resistance in most of the pathogens surveyed.

CONCLUSIONS

Compared with the enormous infectious disease burden and widespread use of antibiotics there are relatively few reliable data on antimicrobial susceptibility from tropical Asia and Africa upon which to draw firm conclusions, although it is evident that many commonly used antibiotics face considerable resistance in prevalent bacterial pathogens. This is likely to exacerbate morbidity and mortality. Investment in improved antimicrobial susceptibility testing and surveillance systems is likely to be a highly cost-effective strategy and should be complemented by centralized and readily accessible information resources.

Antimicrobial resistance among nosocomial isolates in a teaching hospital in goa

Background:

Emergence of polyantimicrobial resistant strains of hospital pathogens has presented a challenge in the provision of good quality in-patient care. Inappropriate use of antibiotics in the hospital is largely responsible for this catastrophe. Bacteriological surveillance of the cases of nosocomial infections is crucial for framing an evidence-based antimicrobial policy for a hospital.

Materials and Methods:

A prospective study was undertaken among 498 patients from medicine and surgery wards in a tertiary teaching hospital in Goa. The patients were followed up clinico-bacteriologically for the occurrence of nosocomial infections (NI). Antibiotic susceptibility testing was done using Kirby-Bauer disc diffusion method.

Results:

The overall infection rate was 33.93 ± 4.16 infections per 100 patients. Urinary tract infection was the most common NI (26.63%), followed by surgical site infection (23.67%), wound infection (23%) and nosocomial pneumonia (18.34%). Ninety-seven percent of the isolates were bacterial, while the others were fungal. More than 80% of the NIs were caused by Gram-negative bacteria, predominantly Pseudomonas aeruginosa, Escherichia coli and Aceinetobacter baumanii. Almost 70% of the isolates were resistant to all the antibiotics for which susceptibility was tested; the rest were sensitive to amikacin, cefoperazone-sulbactam and other antibiotics including methicillin, co-trimoxazole, teicoplenin, vancomycin and rifampicin, either singly or in combination. The proportion of MRSA was 71.4%. Resistance to a particular antibiotic was found to be directly proportional to the antibiotic usage in the study setting.

Conclusion:

Surveillance of nosocomial infections with emphasis on the microbiologic surveillance and frequent antimicrobial audit are critical towards curbing the evil of polyantimicrobial resistant nosocomial infections in a hospital.

Bacterial uropathogens in urinary tract infection and antibiotic susceptibility pattern in jimma university specialized hospital, southwest ethiopia

BACKGROUND

Urinary tract infection (UTI) is one of the most common bacterial infections encountered by clinicians in developing countries. Area-specific monitoring studies aimed to gain knowledge about the type of pathogens responsible for urinary tract infections and their resistance patterns may help the clinician to choose the correct empirical treatment. Therefore, the aim of this study was to determine the type and antibiotic resistance pattern of the urinary pathogens isolated from patients attending Jimma University Specialized Hospital from April to June 2010.

METHODS

A hospital based cross sectional stud was conducted and urine samples were collected using the mid-stream "clean catch" method from 228 clinically-suspected cases of urinary tract infections and tested bacteriologically using standard procedures. Antimicrobial susceptibility test was performed for the isolated pathogens using Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standards Institute guidelines.

RESULTS

Significant bacteria were detected from 9.2% of the total patients. The most common pathogens isolated were Escherichia coli (33.3%), Klebsiella pneumoniae (19%) and S. saprophyticus (14.3%). E. coli and Klebsiella pneumoniae showed the highest percentage of resistance to ampicillin and amoxacillin (100%) however, all isolates of E. coli and K. pneumoniae were susceptible to ciprofloxacin. S. saprophyticus and S. aureus were resistant to ampicillin (100%) and amoxicillin (66.7%). For all UTI isolates, least resistance was observed against drugs such as ceftriaxone, gentamycin and chloramphenicol.

CONCLUSION

This study finding showed that E. coli isolates were the predominant pathogens and the presence of bacterial isolates with very high resistance to the commonly prescribed drugs that in turn leaves the clinicians with very few alternative options of drugs for the treatment of UTIs. As drug resistance among bacterial pathogens is an evolving process, routine surveillance and monitoring studies should be conducted to provide physicians knowledge on the updated and most effective empirical treatment of UTIs.

Species distribution and antimicrobial susceptibility of enterococci isolated from broilers infected experimentally with Eimeria spp and fed with diets containing different supplements

Resistant bacteria in animal can be spread to environment and to humans. Poultry feed and infections caused by Eimeria spp. are important factors in determining the intestinal microbial communities. The aim of this study was to verify the prevalence of species and antimicrobial susceptibility of Enterococcus isolated from broilers fed with different supplements and infected experimentally with Eimeria spp. Broilers were divided in eight groups, fed with diets supplemented with a combination of antimicrobial, ionophore-coccidiostatics, probiotic, essential oil. At 14 days old all birds, except the control, received a solution containing oocysts of Eimeria spp. Samples of cloacal swabs from broilers were collected. A total of 240 Enterococcus sp. strains were isolated, confirmed genus by PCR, classified as species, tested for antimicrobial susceptibility and screened by PCR for the presence of tet(L), tet(M) and erm(B) genes. The overall distribution of species isolated from fecal samples was E. faecalis (40%), followed by E. casseliflavus/E. gallinarum (10.8%), E. mundtii (10.8%), E. faecium (10.8%), E. columbae (5.8%) and E. gallinarum (4.2%). Changes in the composition or frequency of Enterococcus species were observed in all dietary supplementation. Antimicrobial susceptibility tests showed resistance phenotypes a range of antibiotics, especially used in humans such as, streptomycin, penicillin, rifampicin and vancomycin. There was no correlation between different supplementation for broilers and antimicrobial resistance and the presence of tet(M), tet(L) and erm(B) genes. Dietary supplementation had effect on the Enterococcus sp. colonization, but did not have significant effect on the phenotype and genotype of antimicrobial resistance in enterococci.

Multiple introductions of multidrug-resistant tuberculosis into households, Lima, Peru

Two cases of multidrug-resistant tuberculosis (MDR TB) in a household are assumed to reflect within-household transmission. However, in high-incidence areas of MDR TB, secondary cases may arise through exposure to MDR TB in the community. To estimate the frequency of multiple introductions of MDR TB into households, we used spoligotyping and 24-loci mycobacterial interspersed repetitive unit- variable number tandem repeats to classify isolates from 101 households in Lima, Peru, in which >1 MDR TB patient received treatment during 1996-2004. We found different MDR TB strains in >10% of households. Alternate approaches for classifying matching strains produced estimates of multiple introductions in <38% of households. At least 4% of MDR TB patients were reinfected by a second strain of MDR Mycobacterium tuberculosis. These findings suggest that community exposure to MDR TB in Lima occurs frequently. Rapid drug sensitivity testing of strains from household contacts of known MDR TB patients is needed to identify optimal treatment regimens.

Prevalence of antimicrobial resistance and integrons in Escherichia coli from Punjab, Pakistan

Antimicrobial resistance was studied in Escherichia coli strains isolated from urine samples of 457 patients suffering from urinary tract infection. High prevalence of class 1 integrons (43.56%), sulfamethoxazole resistance genes sul1 (45.54%) and sul2 (51.48%) along with occurrence of quinolone resistance genes was detected in multi drug resistance isolates.

Temporal trends in Enterobacter species bloodstream infection: a population-based study from 1998-2007

Enterobacter species are the fourth most common cause of Gram-negative bloodstream infection (BSI). We examined temporal changes and seasonal variation in the incidence rate of Enterobacter spp. BSI, estimated 28-day and 1-year mortality, and determined in vitro antimicrobial resistance rates of Enterobacter spp. bloodstream isolates in Olmsted County, Minnesota, from 1 January 1998 to 31 December 2007. Multivariable Poisson regression was used to examine temporal changes and seasonal variation in incidence rate and Kaplan-Meier method was used to estimate 28-day and 1-year mortality. The median age of patients with Enterobacter spp. BSI was 58 years and 53% were female. The overall age- and gender-adjusted incidence rate of Enterobacter spp. BSI was 3.3 per 100,000 person-years (95% CI 2.3-4.4). There was a linear trend of increasing incidence rate from 0.8 (95% CI 0-1.9) to 6.2 (95% CI 3.0-9.3) per 100,000 person-years between 1998 and 2007 (p 0.002). There was no significant difference in the incidence rate of Enterobacter spp. BSI during the warmest 4 months compared to the remainder of the year (incidence rate ratio 1.06; 95% CI 0.47-2.01). The overall 28-day and 1-year mortality rates of Enterobacter spp. BSI were 21% (95% CI 8-34%) and 38% (95% CI 22-53%), respectively. Up to 13% of Enterobacter spp. bloodstream isolates were resistant to third-generation cephalosporins. To our knowledge, this is the first population-based study to describe the epidemiology and outcome of Enterobacter spp. BSI. The increase in incidence rate of Enterobacter spp. BSI over the past decade, coupled with its associated antimicrobial resistance, dictate the need for further investigation of this syndrome.

Bacterial biofilm shows persistent resistance to liquid wetting and gas penetration

Most of the world's bacteria exist in robust, sessile communities known as biofilms, ubiquitously adherent to environmental surfaces from ocean floors to human teeth and notoriously resistant to antimicrobial agents. We report the surprising observation that Bacillus subtilis biofilm colonies and pellicles are extremely nonwetting, greatly surpassing the repellency of Teflon toward water and lower surface tension liquids. The biofilm surface remains nonwetting against up to 80% ethanol as well as other organic solvents and commercial biocides across a large and clinically important concentration range. We show that this property limits the penetration of antimicrobial liquids into the biofilm, severely compromising their efficacy. To highlight the mechanisms of this phenomenon, we performed experiments with mutant biofilms lacking ECM components and with functionalized polymeric replicas of biofilm microstructure. We show that the nonwetting properties are a synergistic result of ECM composition, multiscale roughness, reentrant topography, and possibly yet other factors related to the dynamic nature of the biofilm surface. Finally, we report the impenetrability of the biofilm surface by gases, implying defense capability against vapor-phase antimicrobials as well. These remarkable properties of B. subtilis biofilm, which may have evolved as a protection mechanism against native environmental threats, provide a new direction in both antimicrobial research and bioinspired liquid-repellent surface paradigms.