High Levels Of Antimicrobial Resistance Research Articles

Escherichia coli ST131, an intriguing clonal group.

In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131.

Laboratory monitoring of bacterial gastroenteric pathogens Salmonella and Shigella in Shanghai, China 2006-2012.

In 2006 we initiated an enhanced laboratory-based surveillance of Salmonella and Shigella infections in Shanghai, China. A total of 4483 Salmonella and 2226 Shigella isolates were recovered from stool specimens by 2012. In 80 identified Salmonella serovars, Enteritidis (34·5%) and Typhimurium (26·2%) were the most common. Shigella (S.) sonnei accounted for 63·9% of human Shigella infections over the same time period, and replaced S. flexneri to become the primary cause of shigellosis since 2010. Overall, a high level of antimicrobial resistance was observed in Salmonella and Shigella, particularly to nalidixic acid, ampicillin, and tetracycline. Ciprofloxacin resistance was common in Salmonella Typhimurium (21·0%) and S. flexneri (37·6%). The cephalosporin resistance in both pathogens also increased over the years, ranging from 3·4% to 7·0% in Salmonella, and from 10·4% to 28·6% in Shigella. Resistance to multiple antimicrobials was also identified in a large number of the isolates. This study provides insight into the distribution of Salmonella and Shigella in diarrhoeal diseases.

Bacterial quality of drinking water sources and antimicrobial resistance profile of Enterobacteriaceae in Bahir Dar city, Ethiopia

A cross-sectional study was conducted to determine the bacterial quality and antimicrobial susceptibility profiles of Enterobacteriaceae from drinking water in Bahir Dar city. A total of 140 water samples were collected in the wet and dry periods from springs (n = 4), reservoirs (n = 10) and private tap water at households (n = 126). Bacteriological analysis of water was conducted using multiple tube method. Overall, 21.4%, 18.6% and 17.8% of drinking water samples had total coliforms (TC), faecal coliforms (FC) and Escherichia coli, respectively. All spring water samples and 29.2% of private tap water had the highest TC load (18 most probable number/100 mL, 95% CI: 100). For FC, 81.4% of the drinking water supplies tested complied with both World Health Organization and Ethiopian Standards. High levels of resistance (98–100%) were observed for ampicillin by Enterobacteriaceae and Pseudomonas aeruginosa. All P. aeruginosa isolates and 20 (66.7%) of E. coli revealed multiple drug resistance. Enterobacteriaceae and P. aeruginosa isolates exhibited high levels of antimicrobial resistance. The bacterial quality of drinking water in Bahir Dar city was poor. Microbial surveillance and monitoring with periodic assessment on physical integrity of the water pipelines need to be undertaken.

Antimicrobial resistance and antimicrobial resistance genes in marine bacteria from salmon aquaculture and non‐aquaculture sites

Antimicrobial resistance (AR) detected by disc diffusion and antimicrobial resistance genes detected by DNA hybridization and polymerase chain reaction with amplicon sequencing were studied in 124 marine bacterial isolates from a Chilean salmon aquaculture site and 76 from a site without aquaculture 8 km distant. Resistance to one or more antimicrobials was present in 81% of the isolates regardless of site. Resistance to tetracycline was most commonly encoded by tetA and tetG; to trimethoprim, by dfrA1, dfrA5 and dfrA12; to sulfamethizole, by sul1 and sul2; to amoxicillin, by blaTEM ; and to streptomycin, by strA-strB. Integron integrase intl1 was detected in 14 sul1-positive isolates, associated with aad9 gene cassettes in two from the aquaculture site. intl2 Integrase was only detected in three dfrA1-positive isolates from the aquaculture site and was not associated with gene cassettes in any. Of nine isolates tested for conjugation, two from the aquaculture site transferred AR determinants to Escherichia coli. High levels of AR in marine sediments from aquaculture and non-aquaculture sites suggest that dispersion of the large amounts of antimicrobials used in Chilean salmon aquaculture has created selective pressure in areas of the marine environment far removed from the initial site of use of these agents.

High in vitro activity of a novel dual bacterial topoisomerase inhibitor of the ATPase activities of GyrB and ParE (VT12-008911) against Neisseria gonorrhoeae isolates with various high-level antimicrobial resistance and multidrug resistance

Clinical resistance to the currently recommended extended-spectrum cephalosporins (ESCs), the last remaining options for empirical antimicrobial monotherapy of gonorrhoea globally, has been reported. New antimicrobials are essential to avoid the emergence of untreatable gonorrhoea. We have investigated the in vitro activity of a novel dual bacterial topoisomerase inhibitor of the ATPase activities of GyrB and ParE (Vertex aminobenzimidazole VT12-008911), compared with antimicrobials currently or previously recommended for gonorrhoea treatment. MICs were determined using agar dilution (VT12-008911) or Etest (seven antimicrobials) for international reference strains (n = 28) and clinical Neisseria gonorrhoeae isolates (n = 220). The latter included three extensively drug-resistant isolates with high-level ceftriaxone resistance, additional isolates with clinical ESC resistance and a high number of isolates with ciprofloxacin resistance and multidrug resistance. The MIC(50), MIC(90) and MIC range of VT12-008911 were 0.064, 0.125 and ≤0.002-0.25 mg/L, respectively. One-hundred and seventy (69%) isolates were ciprofloxacin resistant; however, only 54 of those isolates had a VT12-008911 MIC >0.064 mg/L (47 and 7 with MIC = 0.125 mg/L and MIC = 0.25 mg/L, respectively). The in vitro activity of VT12-008911 was superior to that of ciprofloxacin and all additional antimicrobials investigated. Time-kill curve analysis showed that VT12-008911 exhibited potent time-dependent bactericidal activity, at or very close to the MIC, against N. gonorrhoeae. In vitro results suggest that VT12-008911 might be an effective treatment option for gonorrhoea. However, it will be important to detail the pharmacokinetics/pharmacodynamics, toxicity, selection and mechanisms of VT12-008911 resistance in N. gonorrhoeae and, finally, to perform well-designed in vivo randomized clinical trials.

Expression of MexAB‐OprM efflux pump system and susceptibility to antibiotics of different Pseudomonas aeruginosa clones isolated from patients hospitalized in two intensive care units at University Hospital in Bialystok (northeastern Poland) between January 2002 and December 2009

We investigated the genetic similarities and expression of the MexAB-OprM efflux pump system in different clones of multiresistant Pseudomonas aeruginosa strains collected from 2002 to 2009 at two intensive care units (ICU). Regulatory and structural genes mexB, mexR, and mexA were found in 99%, 98%, and 94% of tested strains, respectively. The presence of class 1 integron was found in 90% of the strains, while class 2 integron in only one strain (Psa506). Class 3 integron was not found in any of the tested strains. Among the eleven clones identified, only two clones, I and D, exhibited higher levels of mexB gene expression than the other clones. Clone I had the highest expression (FC=10.36, p <0.05). The results of our study indicated a high level of MexAB-OprM pump expression in groups of strains isolated in the years 2008-2009 (FC=12.92, p<0.03) and 2002-2006 (FC=5.14, p<0.03). There were no statistically significant differences in resistance to all tested antibiotics among the various clones. The high level of antimicrobial resistance may have been due to the coexistence of different resistance mechanisms among the studied P.aeruginosa strains. However, this does not exclude the contribution of the MexAB-OprM pump, particularly in resistance to meropenem and ciprofloxacin.

Prevalence and Antimicrobial Resistance of Enterococcus Species: A Hospital-Based Study in China

Objective: to investigate the prevalence and antimicrobial resistance of Enterococcus species isolated from a university hospital, and explore the mechanisms underlying the antimicrobial resistance, so as to provide clinical evidence for the inappropriate clinical use of antimicrobial agents and the control and prevention of enterococcal infections. Methods: a total of 1,157 enterococcal strains isolated from various clinical specimens from January 2010 to December 2012 in the General Hospital of Ningxia Medical University were identified to species level with a VITEK-2 COMPACT fully automated microbiological system, and the antimicrobial susceptibility of Enterococcus species was determined using the Kirby-Bauer disc diffusion method. The multiple-drug resistant enterococcal isolates were screened from the clinical isolates of Enterococcus species from the burns department. The minimal inhibitory concentration (MIC) of Enterococcus species to the three fluoroquinolones, including ciprofloxacin, gatifloxacin and levofloxacin was determined with the agar dilution method, and the changes in the MIC of Enterococcus species to the three fluoroquinolones following reserpine treatment were evaluated. The β-lactam, aminoglycoside, tetracycline, macrolide, glycopeptide resistance genes and the efflux pump emeA genes were detected in the enterococcal isolates using a polymerase chain reaction (PCR) assay. Results: the 1,157 clinical isolates of Enterococcus species included 679 E. faecium isolates (58.7%), 382 E. faecalis isolates (33%), 26 E. casseliflavus isolates (2.2%), 24 E. avium isolates (2.1%), and 46 isolates of other Enterococcus species (4%). The prevalence of antimicrobial resistance varied significantly between E. faecium and E. faecalis, and ≤1.1% of these two Enterococcus species were found to be resistant to vancomycin, teicoplanin or linezolid. In addition, the Enterococcus species isolated from different departments of the hospital exhibited various resistances to the same antimicrobial agent, while reserpine treatment reduced the resistance of Enterococcus species to ciprofloxacin, gatifloxacin and levofloxacin. The β-lactamase gene TEM, aminoglycoside-modifying-enzyme genes aac(6')-aph(2"), aph(3')-III, ant(6)-I and ant(2")-I, tetracycline resistance gene tetM, erythromycin resistance gene ermB, vancomycin resistance gene vanA and the enterococcal multidrug resistance efflux emeA gene were detected in 77%, 62%, 26%, 13%, 36%, 31%, 66%, 5% and 55% of the 100 multiple-drug resistant enterococcal isolates. Conclusions: similar to previous findings, E. faecium and E. faecalis are predominant conditionally pathogenic bacteria that cause hospital-acquired infections that can cause urinary and respiratory system infections. Multiple and high-level antimicrobial resistance is highly prevalent in the hospital isolates of Enterococcus species. Reserpine treatment inhibits the active efflux of Enterococcus species to ciprofloxacin, gatifloxacin and levofloxacin in vitro and reduces the MIC of Enterococcus species to these three fluoroquinolones. The presence of the enterococcal multidrug resistance efflux emeA gene is associated with the resistance to antibiotics in Enterococcus species. The monitoring of the prevalence and antimicrobial resistance of Enterococcus species is of great significance to guide the control and prevention of enterococcal infections.

Identification, Characterization and Antibiotic Susceptibility of Indoor Airborne Bacteria in Selected Wards of Hawassa University Teaching and Referral Hospital, South Ethiopia

IDENTIFICATION, CHARACTERIZATION AND ANTIBIOTIC SUSCEPTIBILITY OF INDOOR AIRBORNE BACTERIA IN SELECTED WARDS OF HAWASSA UNIVERSITY TEACHING AND REFERRAL HOSPITAL, SOUTH ETHIOPIA By: Diriba Leta Weleni Address: e-mail- Dirleta2009@gmail.com ABSTRACT Atmospheric pollution is one of the most pressing problems of our age. This pollution has now reached advanced level that poses a potential threat to the health and wellbeing of the population. Nosocomial infection (NI) is an infection occurring in a patient in a hospital or other health care facility in whom the infection was not present or incubating at the time of admission. One of the risk factors for such infection is bacterial contamination of hospital wards indoor air by bacteria. In view of this, the microbiological quality of air can be considered as a mirror of the hygienic condition for hospital wards. A cross sectional study was conducted from May to August 2011 in central triage, emergency, surgical outpatient, medical outpatient, gynecology and obstetrics, pediatrics, surgical inpatient and medical inpatient wards of Hawassa Teaching Referral Hospital to assess the bacteriological quality of indoor air and to determine the antibiotic susceptibility of the isolates. Air samples of the selected wards were collected using Settle Plate Method in the morning and in the afternoons and cultured aerobically. Of the 128 indoor air samples collected from the hospital rooms 124 (96.9%) were culture positive resulting in 153 isolate of nine spp/genera of bacteria. Gram negative and Gram positive bacteria accounted for 56.9 and 43.1% of the isolates respectively. The bacteria isolated were S. aureus (25.4%), Klebsiella spp. (24.8%), Proteus spp. (11.8%), coagulase negative streptococci (CNS) (10.5%), Serratia spp. (9.2%), Streptococci spp. (7.2%), E. coli (4.6%), Citrobacter (4.0%) and Enterobacter spp. (2.6%). No difference was observed in type and frequency of bacterial isolates among the different wards and between samples collected in the morning and in the afternoon (P >0.05). High level of antimicrobial resistance was observed among the isolates obtained in this study; 86.9% were resistant to 1 or more antimicrobials and 73.8% were multidrug resistant. Resistance was especially high against amoxicillin (64.9%) and penicillin (58.4%). Hospital management was advised to reduce foot trafficking and to periodically assess the quality of indoor air to identify and minimize/eliminate sources of microbial contamination. Key words: Bio-aerosols, Hawassa, Indoor environments, Nosocomial infections, Settle Plate method

Infecções do trato urinário (ITU) de cães e gatos: etiologia e resistência aos antimicrobianos

As infecções bacterianas do trato urinário (ITUs) são causa comum de doença em cães, gatos e humanos. Embora bactérias Gram positivas como Staphylococcus spp., Streptococcus spp. e Enterococcus spp., possam ocasionar ITUs, as bactérias Gram negativas (Escherichia coli, Proteus spp., Klebsiella spp., Pseudomonas spp. e Enterobacter spp.) respondem por 75% dos casos. Este estudo teve como objetivo determinar a frequência de diferentes gêneros de bactérias em ITUs em cães e gatos, bem como a sua sensibilidade aos antimicrobianos utilizados na rotina clínica. Portanto, amostras de urina de 100 cães e gatos com sinais de ITU foram coletadas assepticamente, sofrendo avaliação microbiológica por meio de métodos qualitativos e quantitativos, além de urinálise. Todos os isolados foram submetidos a testes de sensibilidade aos antimicrobianos. ITU foi confirmada em 74% dos animais, não havendo predominância quanto ao sexo. No que diz respeito à idade, 85% dos cães e 87% dos gatos tinham idades superiores a seis anos. Noventa e cinco cepas bacterianas foram isoladas, com maior frequência de Escherichia coli (55% do total) dos sorogrupos O6 e O2. Constatou-se níveis elevados de resistência a antimicrobianos nas cepas isoladas. Para as cepas Gram positivas, tetraciclina (46,1%), enrofloxacina, cotrimazol e estreptomicina (42,3% cada) foram as drogas com os maiores índices de resistência. Para as Gram negativas, amoxacilina e tetraciclina apresentaram percentuais acima de 50%. Multiresistência foi verificada em mais de 50% dos principais gêneros isolados. Considerando-se que as cepas de E. coli apresentam potencial zoonótico e forte participação na disseminação de resistência aos antimicrobianos, ressalta-se a importância do papel do médico veterinário na prevenção e controle das ITUs animais e sua contribuição para a saúde pública.

Five-year prospective surveillance of nosocomial bloodstream infections in an Estonian paediatric intensive care unit

Few studies provide rates of nosocomial bloodstream infections (BSIs) in mixed neonatal and paediatric intensive care units (PICUs). To determine the rate, pathogens and outcome of BSIs in an Estonian PICU. Data were collected prospectively from 1st January 2004 to 31st December 2008 in the PICU of Tartu University Hospital. The definition criteria of the US Centers for Disease Control and Prevention were applied for the diagnosis of laboratory-confirmed BSI. A total of 126 episodes of BSI were identified in 89 patients (74 neonates, eight infants, seven patients aged >1 year). Among neonates 42 (57%) had birth weight <1000 g. The overall incidence of BSI was 9.2 per 100 admissions, incidence density 12.8 per 1000 patient-days. Primary BSI was diagnosed in 92 episodes. Central line (CL)-associated BSI incidence density for neonates was 8.6 per 1000 CL-days with the highest incidence (27.4) among neonates with extremely low birth weight. The most common pathogens were coagulase-negative staphylococci (43%) and Serratia marcescens (14%). Resistance to meticillin was detected in four out of seven S. aureus isolates (all were part of an outbreak) and 23% of Enterobacteriaceae were extended spectrum beta-lactamase (ESBL)-producing strains. Overall case-fatality rate was 10%. We observed higher rates of BSIs in our mixed PICU than reported previously. High levels of antimicrobial resistance were detected. Future research should focus on the effects of infection control measures to prevent outbreaks and to decrease incidence of CL-associated BSI.

Tracking the establishment of local endemic populations of an emergent enteric pathogen

Shigella sonnei is a human-adapted pathogen that is emerging globally as the dominant agent of bacterial dysentery. To investigate local establishment, we sequenced the genomes of 263 Vietnamese S. sonnei isolated over 15 y. Our data show that S. sonnei was introduced into Vietnam in the 1980s and has undergone localized clonal expansion, punctuated by genomic fixation events through periodic selective sweeps. We uncover geographical spread, spatially restricted frontier populations, and convergent evolution through local gene pool sampling. This work provides a unique, high-resolution insight into the microevolution of a pioneering human pathogen during its establishment in a new host population.

An epidemiological investigation ofCampylobacterin pig and poultry farms in the Mekong delta of Vietnam

Campylobacter are zoonotic pathogens commonly associated with gastroenteritis. To assess the relevance of Campylobacter in Vietnam, an economically transitioning country in SE Asia, we conducted a survey of 343 pig and poultry farms in the Mekong delta, a region characterized by mixed species farming with limited biosecurity. The animal-level prevalence of Campylobacter was 31·9%, 23·9% and 53·7% for chickens, ducks and pigs, respectively. C. jejuni was predominant in all three host species, with the highest prevalence in pigs in high-density production areas. Campylobacter isolates demonstrated high levels of antimicrobial resistance (21% and 100% resistance against ciprofloxacin and erythromycin, respectively). Multilocus sequence type genotyping showed a high level of genetic diversity within C. jejuni, and predicted C. coli inter-species transmission. We suggest that on-going intensification of animal production systems, limited biosecurity, and increased urbanization in Vietnam is likely to result in Campylobacter becoming an increasingly significant cause of human diarrhoeal infections in coming years.

Studies of selective decontamination

On the basis of a systematic review and meta-analysis, Nick Daneman and colleagues, concluded that there was no evidence for increased colonisation or infection with antimicrobial-resistant bacteria in patients receiving selective digestive decontamination (SDD) or selective oropharyngeal decontamination (SOD). The investigators recommend future studies focus on long-term effects of these interventions on antibiotic resistance with a non-crossover cluster-randomised study design. Importantly, the only evidence of better survival with SDD or SOD comes from studies in intensive-care units (ICUs) where—among isolates causing ICU-acquired bacteraemia—less than 1% were resistant to meticillin for Staphylococcus aureus or vancomycin for enterococci, and less than 5% of Escherichia coli and Klebsiella spp were producing extended-spectrum β lactamases.2de Jonge E Schultz MJ Spanjaard L et al.Effects of selective decontamination of digestive tract on mortality and acquisition of resistant bacteria in intensive care: a randomised controlled trial.Lancet. 2003; 362: 1011-1016Summary Full Text Full Text PDF PubMed Scopus (491) Google Scholar, 3de Smet AM Kluytmans JA Cooper BS et al.Decontamination of the digestive tract and oropharynx in ICU patients.N Engl J Med. 2009; 360: 20-31Crossref PubMed Scopus (594) Google Scholar, 4Krueger WA Lenhart FP Neeser G et al.Influence of combined intravenous and topical antibiotic prophylaxis on the incidence of infections, organ dysfunctions, and mortality in critically ill surgical patients: a prospective, stratified, randomized, double-blind, placebo-controlled clinical trial.Am J Respir Crit Care Med. 2002; 166: 1029-1037Crossref PubMed Scopus (229) Google Scholar Whether these findings can be extrapolated to settings with higher levels of antimicrobial resistance is unknown. Unless future studies are (again) done in settings with low levels of antibiotic resistance, clinically significant benefits in unambiguous outcomes for patients, preferably survival, should be the primary focus. Therefore, such studies should include standard-of-care treatment (no SDD or SOD), and investigators should consider chlorhexidine oropharyngeal decontamination as a comparator because this intervention has also been association with prevention of ventilator-associated pneumonia,5Koeman M van der Ven AJ Hak E et al.Oral decontamination with chlorhexidine reduces the incidence of ventilator-associated pneumonia.Am J Respir Crit Care Med. 2006; 173: 1348-1355Crossref PubMed Scopus (308) Google Scholar but has never been compared with SDD or SOD. We fully agree that randomly assigning units instead of patients is the most appropriate design in view of the unit-wide ecological effect pursued. However, the inherent absence of individual randomisation in a cluster randomised study increases the risk of bias caused by systematic differences in baseline characteristics of patients between intervention groups, especially when the intervention is known at time of enrolment, as will be the case when trying to modify the unit-wide ecology. Adjustment for covariates is then needed, which reduces the precision of the effect estimate. Moreover, ICUs might differ in characteristics that are difficult to quantify, but could substantially change study outcomes, such as hand hygiene and antibiotic use. A crossover design would minimise effects of such variables. Therefore, we recommend a cluster-randomised crossover study comparing SDD, SOD, and chlorhexidine to standard care in contemporary settings of antimicrobial resistance. This approach will examine the effectiveness of decontamination strategies on patients' outcomes, before we focus on the long-term consequences of SDD and SOD on antibiotic resistance in such settings. BHJW is supported by funding from the European Community's Seventh Framework Programme ( FP7/2007-2013 ) under grant agreement 282512. MJMB is supported by The Netherlands Organization of Scientific Research ( NWO-VICI 918.76.611 ). Effect of selective decontamination on antimicrobial resistance in intensive care units: a systematic review and meta-analysisWe detected no relation between the use of SDD or SOD and the development of antimicrobial-resistance in pathogens in patients in the ICU, suggesting that the perceived risk of long-term harm related to selective decontamination cannot be justified by available data. However, our study indicates that the effect of decontamination on ICU-level antimicrobial resistance rates is understudied. We recommend that future research includes a non-crossover, cluster randomised controlled trial to assess long-term ICU-level changes in resistance rates. Full-Text PDF Studies of selective decontamination – Authors' replyJames Hurley and Bastiaan Wittekamp and colleagues discuss some of the fascinating and controversial aspects of selective digestive decontamination (SDD) and sound the call for further research to clarify its benefits and risks in intensive care units (ICUs). We agree with Hurley that the greatest limitation of previous research is that it has largely involved patient-level randomisation in single ICUs. We share his concern that this could lead to cross-transmission of antimicrobial-resistant pathogens from intervention to control patients, and mask signals of increased antibiotic resistance. Full-Text PDF

Tracking Pathogen Transmission at the Human–Wildlife Interface: Banded Mongoose and Escherichia coli

A primary challenge to managing emerging infectious disease is identifying pathways that allow pathogen transmission at the human-wildlife interface. Using Escherichia coli as a model organism, we evaluated fecal bacterial transmission between banded mongoose (Mungos mungo) and humans in northern Botswana. Fecal samples were collected from banded mongoose living in protected areas (n=87, 3 troops) and surrounding villages (n=92, 3 troops). Human fecal waste was collected from the same environment (n=46). Isolates were evaluated for susceptibility to 10 antibiotics. Resistant E. coli isolates from mongoose were compared to human isolates using rep-PCR fingerprinting and MLST-PCR. Antimicrobial resistant isolates were identified in 57 % of the mongoose fecal samples tested (range 31-78% among troops). At least one individual mongoose fecal sample demonstrated resistance to each tested antibiotic, and multidrug resistance was highest in the protected areas (40.9%). E. coli isolated from mongoose and human sources in this study demonstrated an extremely high degree of genetic similarity on rep-PCR (AMOVA, F ST=0.0027, p=0.18) with a similar pattern identified on MLST-PCR. Human waste may be an important source of microbial exposure to wildlife. Evidence of high levels of antimicrobial resistance even within protected areas identifies an emerging health threat and highlights the need for improved waste management in these systems.

Diversity of Streptococcus mutans strains in bacterial interspecies interactions

Biofilms are matrix-enclosed microbial population adhere to each other and to surfaces. Compared to planktonic bacterial cells, biofilm cells show much higher levels of antimicrobial resistance. We aimed to investigate Streptococcus mutans strain diversity in biofilm formation and chlorhexidine (CHX) resistance of single S. mutans and dual S. mutans-Enterococcus faecalis biofilms. Four clinical S. mutans strains (C180-2, C67-1, HG723 and UA159) formed 24-h biofilms with or without an E. faecalis strain. These biofilms were treated for 10 min with 0.025% CHX. Biofilm formation, CHX resistance and S.mutans-E. faecalis interactions were evaluated by biomass staining, resazurin metabolism, viable count and competition agar assays. The main finding is that the presence of E. faecalis generally reduced all dual-species biofilm formation, but the proportions of S. mutans in the dual-species biofilms as well as CHX resistance displayed a clear S. mutans strain dependence. In particular, decreased resistance against CHX was observed in dual S. mutans C67-1 biofilms, while increased resistance was found in dual S. mutans UA159 biofilms. In conclusion, the interaction of S. mutans with E. faecalis in biofilms varies between strains, which underlines the importance of studying strain diversity in inter-species virulence modulation and biofilm antimicrobial resistance.

Community-associated, methicillin-susceptible, and methicillin-resistant Staphylococcus aureus bone and joint infections in children

Previously, the treatment of Staphylococcus aureus infections was less complex, as most of those isolated were susceptible to β-lactam antibiotics. In recent years, there has been a marked increase in the incidence of invasive community-acquired (CA) methicillin-resistant S. aureus (MRSA) among children worldwide. However, data on the clinical characteristics and outcomes related to pediatric bone and joint infections caused by CA-S. aureus are very limited in India. In this tertiary hospital-based study, 74 patients with invasive S. aureus less than 18 years of age were identified between January 2004 and December 2008. All patients fulfilled the case definition of CA-S. aureus with evidence of infection before admission; they presented to our hospital without previous antibiotic use and were culture positive for S. aureus within 48 h of admission. All data including demographics, clinical features, treatment protocol, laboratory findings, and antimicrobial susceptibilities were recorded and compared using the SPSS 11.5 statistical software. Of the 74 patients with culture-positive S. aureus bone and joint infection, 41 had MRSA (55%). Forty-nine patients (66.2%) had osteomyelitis, of whom 29 (59.18%) had MRSA and 25 (33.7%) had septic arthritis, of whom 12 (48%) had MRSA. The MRSA group had a significantly higher erythrocyte sedimentation rate, C-reactive protein value, neutrophil count, and white blood cell count (P<0.05). The MRSA group also had longer duration of febrile days, hospital stay, and antibiotic course compared with the methicillin-susceptible S. aureus (MSSA) group (P<0.05). A clinical predictive algorithm was developed using seven significant independent multivariate predictors, with the probability of MRSA being 94% if all seven predictors were positive and 9% if five predictors were positive. Resistance to many classes of antibiotics was noted among S. aureus isolates including trimethoprim-sulfamethoxazole (MRSA 80%, MSSA 24%), erythromycin (MRSA 83%, MSSA 67%), clindamycin (MRSA 54%, MSSA 34%), and ciprofloxacin (MRSA 61%, MSSA 48%). No vancomycin resistance was observed. The morbidity associated with MRSA bone and joint infection in children is significantly higher than that caused by MSSA. Early diagnosis at the primary healthcare level and treatment with appropriate antistaphylococcal therapy are crucial to achieve optimal clinical outcomes. High levels of antimicrobial resistance of both MSSA and MRSA isolates to several classes of antibiotics are a major concern warranting the need for antimicrobial stewardship and ongoing surveillance.

Community acquired infections in older patients admitted to hospital from care homes versusthe community: cohort study of microbiology and outcomes

BackgroundResidents of care homes are at risk of colonisation and infection with antibiotic resistant bacteria, but there is little evidence that antibiotic resistance among such patients is associated with worse outcomes than among older people living in their own homes. Our aim was to compare the prevalence of antibiotic resistant bacteria and clinical outcomes in older patients admitted to hospital with acute infections from care homes versus their own homes.MethodsWe enrolled patients admitted to Ninewells Hospital in 2005 who were older than 64 years with onset of acute community acquired respiratory tract, urinary tract or skin and soft tissue infections, and with at least one sample sent for culture. The primary outcome was 30 day mortality, adjusted for age, sex, Charlson Index of co-morbidity, sepsis severity, presence of resistant isolates and resistance to initial therapy.Results161 patients were identified, 60 from care homes and 101 from the community. Care home patients were older, had more co-morbidities, and higher rates of resistant bacteria, including MRSA and Gram negative organisms resistant to co-amoxiclav, cefuroxime and/or ciprofloxacin, overall (70% versus 36%, p = 0.026). 30 day mortality was high in both groups (30% in care home patients and 24% in comparators). In multivariate logistic regression we found that place of residence did not predict 30 day mortality (adjusted odds ratio (OR) for own home versus care home 1.01, 95% CI 0.40-2.52, p = 0.984). Only having severe sepsis predicted 30 day mortality (OR 10.09, 95% CI 3.37-30.19, p < 0.001), after adjustment for age, sex, co-morbidity, presence of resistant bacteria, resistance to initial therapy, and place of residence.ConclusionsOlder patients admitted with acute infection had high 30 day mortality. Patients from care homes were more likely to have resistant organisms but high levels of antimicrobial resistance were found in both groups. Thus, we recommend that antibiotic therapies active against resistant organisms, guided by local resistance patterns, should be considered for all older patients admitted with severe sepsis regardless of their place of residence.

Epidemiological Relationship of EnterotoxigenicEscherichia coliand EnteroaggregativeE. coliIsolated from Patients with Diarrhea in Seoul

Of total 1,438 specimens of patients with diarrhea in Seoul, 2011, 217 samples (15%) were found pathogenic Escherichia coli that included 192 strains (89%) of enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAEC). The highest isolation rate for ETEC and EAEC was found in August and September. Sixty two pathogenic E. coli strains (34 ETEC and 28 EAEC strains) were selected from 175 strains (94 ETEC and 81 EAEC strains) isolated in August and September. Of 94 strains characterized for ETEC phenotype, 76 (81%) expressed heat-stable toxin (ST) only. Antimicrobial susceptibility test was carried out by using sixteen types of antibiotics. A high level of antimicrobial resistance to tetracycline (57%), ampicillin and ticarcillin (54%) was observed among EAEC isolates while the highest resistance rate of ETEC was found for nalidixic acid (47%), followed by tetracycline (32%). As to the antimicrobial susceptibility test, EAEC showed the complicated multi-drug resistant patterns in which the resistance was higher than ETEC. Pulsed-field gel electrophoresis (PFGE) was carried out to examine the genetic relatedness among ETEC and EAEC isolates. Except for 11 strains, 51 strains were divided by eight pulsotypes. In PFGE analysis, isolates from foodborne disease outbreaks in August and September 2011 showed close relation.

Antimicrobial Susceptibility Patterns of the Bacterial Isolates in Post-Operative Wound Infections in a Tertiary Care Hospital, Kathmandu, Nepal

Unrestrained anti-microbial resistance (AMR) among bacterial pathogens has made the management and treatment of post-operative wound infections difficult. This study assessed the current AMR patterns of bacterial isolates in post-operative wound infections in a tertiary care hospital in Kathmandu,Nepal. Pus swabs collected from post-operative wound infections and submitted for culture and sensitivity were included in this study. Isolation and identification of the organism was done by standard microbiological methods. Antibiotic susceptibility test was performed by Kirby Bauer disc diffusion method and result was interpreted as per National Committee for Clinical Laboratory Standards (NCCLS) guide lines. Of the 120 pus swabs processed for culture, 96 showed bacterial growth. Staphylococcus aureus 36 (37.5%) was the predominant gram positive isolate and Escherichia coli 24 (25%) was the major gram negative isolate .The infection was most prevalent in the age group 20-40 years. All S. aureus isolates were sensitive to aminoglycosides and vancomycin. Out of 36 S. aureus, 15 (41.66%) isolates were methicillin resistant S. aureus (MRSA). Staphylococcus epidermidis showed high resistance (50%-100%) to all antibiotics but were sensitive to vancomycin. All gram negative isolates showed high resistance against cephalexin (75%-100%) and ceftriaxone (25%-100%). Overall multi-drug resistant isolates were 66.7%. A high level of AMR was observed in gram negative bacterial isolates. Rational use of antibiotics and a regular monitoring of AMR patterns in post-operative wound infections are essential and mandatory to avert further emergence and spread of anti-microbial resistance among bacterial pathogens.

Candida species: current epidemiology, pathogenicity, biofilm formation, natural antifungal products and new therapeutic options

The incidence of fungal infections has increased significantly, so contributing to morbidity and mortality. This is caused by an increase in antimicrobial resistance and the restricted number of antifungal drugs, which retain many side effects. Candida species are major human fungal pathogens that cause both mucosal and deep tissue infections. Recent evidence suggests that the majority of infections produced by this pathogen are associated with biofilm growth. Biofilms are biological communities with a high degree of organization, in which micro-organisms form structured, coordinated and functional communities. These biological communities are embedded in a self-created extracellular matrix. Biofilm production is also associated with a high level of antimicrobial resistance of the associated organisms. The ability of Candida species to form drug-resistant biofilms is an important factor in their contribution to human disease. The study of plants as an alternative to other forms of drug discovery has attracted great attention because, according to the World Health Organization, these would be the best sources for obtaining a wide variety of drugs and could benefit a large population. Furthermore, silver nanoparticles, antibodies and photodynamic inactivation have also been used with good results. This article presents a brief review of the literature regarding the epidemiology of Candida species, as well as their pathogenicity and ability to form biofilms, the antifungal activity of natural products and other therapeutic options.