Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae: considerations for diagnosis, prevention and drug treatment

Efflux as a mechanism of antimicrobial drug resistance in clinical relevant microorganisms: the role of efflux inhibitors

INTRODUCTION

Microbial resistance against antibiotics is a serious threat to the effective treatment of infectious diseases. Several mechanisms exist through which microorganisms can develop resistance against antimicrobial drugs, of which the overexpression of genes to produce efflux pumps is a major concern. Several efflux transporters have been identified in microorganisms, which infer resistance against specific antibiotics and even multidrug resistance. Areas covered: This paper focuses on microbial resistance against antibiotics by means of the mechanism of efflux and gives a critical overview of studies conducted to overcome this problem by combining efflux pump inhibitors with antibiotics. Information was obtained from a literature search done with MEDLINE, Pubmed, Scopus, ScienceDirect, OneSearch and EBSCO host. Expert opinion: Efflux as a mechanism of multidrug resistance has presented a platform for improved efficacy against resistant microorganisms by co-administration of efflux pump inhibitors with antimicrobial agents. Although proof of concept has been shown for this approach with in vitro experiments, further research is needed to develop more potent inhibitors with low toxicity which is clinically effective.

Antimicrobial Resistance in the Intensive Care Unit

Bacterial infections are a frequent cause of hospitalization, and nosocomial infections are an increasingly common condition, particularly within the acute/critical care setting. Infection control practices and new antimicrobial development have primarily focused on gram-positive bacteria; however, in recent years, the incidence of infections caused by gram-negative bacteria has risen considerably in intensive care units. Infections caused by multidrug-resistant (MDR) gram-negative organisms are associated with high morbidity and mortality, with significant direct and indirect costs resulting from prolonged hospitalizations due to antibiotic treatment failures. Of particular concern is the increasing prevalence of antimicrobial resistance to β-lactam antibiotics (including carbapenems) among Pseudomonas aeruginosa and Acinetobacter baumannii and, recently, among pathogens of the Enterobacteriaceae family. Treatment options for infections caused by these pathogens are limited. Antimicrobial stewardship programs focus on optimizing the appropriate use of currently available antimicrobial agents with the goals of improving outcomes for patients with infections caused by MDR gram-negative organisms, slowing the progression of antimicrobial resistance, and reducing hospital costs. Newly approved treatment options are available, such as β-lactam/β-lactamase inhibitor combinations, which significantly extend the armamentarium against MDR gram-negative bacteria.

Treatment options for extended-spectrum beta-lactamase (ESBL) and AmpC-producing bacteria

INTRODUCTION

Extended spectrum β-lactamases (ESBL) and AmpC β-lactamases are increasing causes of resistance in many Gram-negative pathogens of common infections. This has led to a growing utilization of broad spectrum antibiotics, most predominately the carbapenem agents. As the prevalence of ESBL and AmpC-producing isolates and carbapenem resistance has increased, interest in effective alternatives for the management of these infections has also developed.

AREAS COVERED

This article summarizes clinical literature evaluating the utility of carbapenem-sparing regimens for the treatment of ESBL and AmpC-producing Enterobacteriaceae, mainly β-lactam-β-lactamase inhibitor combinations and cefepime (FEP).

EXPERT OPINION

Based on available data, the use of piperacillin-tazobactam (PTZ) and FEP in the treatment of ESBL-producing Enterobacteriaceae cannot be widely recommended. However, certain infections and patient characteristics may support for effective use of these alternative agents. In the treatment of infections caused by AmpC-producing Enterobacteriaceae, FEP has been shown to be a clinically useful carbapenem-sparing alternative. Carbapenems and FEP share many structurally similar characteristics in regards to susceptibility to AmpC β-lactamases, which further create confidence in the use FEP in these situations. Patient and infection specific characteristics should be used to employ FEP optimally.

Occurrence and characteristics of extended spectrum beta-lactamases-producing Enterobacteriaceae from foods of animal origin

Presence of extended spectrum beta-lactamases (ESBL) in bacteria is a growing health concern of global significance. The local, regional, national, and international epidemiological studies for extended spectrum beta-lactamases-producing Enterobacteriaceae and their encoding genes in foods are still incomplete. The objective of this study was to determine the occurrence of extended spectrum beta-lactamases-producing Enterobacteriaceae and the characteristics of their encoding genes from a total of 250 samples of various foods of animal-origin (100 raw chicken meat, 100 raw cow milk, and 50 raw cow milk cheese) sold in Turkey. Overall, 55 isolates were positive as extended spectrum beta-lactamases-producing Enterobacteriaceae. The most prevalent extended spectrum beta-lactamases-producing strain were identified as Escherichia coli (80%), followed by Enterobacter cloacae (9.1%), Citrobacter braakii (5.5%), Klebsiella pneumoniae (3.6%), and Citrobacter werkmanii (1.8%) by Vitek^® MS. The simultaneous production of extended spectrum beta-lactamases and AmpC was detected in five isolates (9.1%) in E. coli (80%) and E. cloacae (20%). The frequency rates of bla_TEM, bla_CTX-M, and bla_SHV were 96.4%, 53.7%, and 34.5%, respectively. The co-existence of bla-genes was observed in 82% of extended spectrum beta-lactamases producers with a distribution of bla_TEM & bla_CTX-M (52.7%), bla_TEM & bla_SHV (20%), bla_TEM & bla_CTX-M & bla_SHV (12.7%), and bla_SHV & bla_CTX-M (1.8%). The most prevalent variant of bla_CTX-M clusters was defined as bla_CTX-M-1 (97.2%), followed by bla_CTX-M-8 (2.8%). In summary, the analysed foods were found to be posing a health risk for Turkish consumers due to contamination by Enterobacteriaceae with a diversity of extended spectrum beta-lactamases encoding genes.

Evaluation of cephamycins as supplements to selective agar for detecting Campylobacter spp. in chicken carcass rinses

Although cefoperazone is the most commonly used antibiotic in Campylobacter-selective media, the distribution of cefoperazone-resistant bacteria such as extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is increasing. Here we evaluated the potential of cephamycins for use as supplements to improve modified charcoal-cefoperazone-deoxycholate agar (mCCDA) by replacing cefoperazone with the same concentrations (32 mg/L) of cefotetan (modified charcoal-cefotetan-deoxycholate agar, mCCtDA) and cefoxitin (modified charcoal-cefoxitin-deoxycholate agar, mCCxDA). In chicken carcass rinse samples, the number of mCCDA plates detecting for Campylobacter (18/70, 26%) was significantly lower than that of mCCtDA (42/70, 60%) or mCCxDA plates (40/70, 57%). The number of mCCDA plates (70/70, 100%) that were contaminated with non-Campylobacter species was significantly higher than that of mCCtDA (20/70, 29%) or mCCxDA plates (21/70, 30%). The most common competing species identified using mCCDA was ESBL-producing E. coli, while Pseudomonas species frequently appeared on mCCtDA and mCCxDA.

Prevalence of Quinolone Resistance Genes Among Extended-Spectrum B-Lactamase-Producing Escherichia coli in Mashhad, Iran

Background:

Escherichia coli is an important bacterial species based on incidence and associated infection severity. Some E. coli strains produce extended-spectrum beta lactamase (ESBL) and are called ESBL-producing E. coli. These strains are resistant to most classes of cephalosporin and a number of other classes of antibiotics. Plasmids carrying qnr genes have been found to transmit quinolone resistance.

Objectives:

The aim of this study was to determine the frequency of qnr genes in ESBL-producing and non-ESBL-producing E. coli isolated from outpatient and hospitalized patient clinical specimens from Imam Reza hospital in Mashhad, Iran.

Materials and Methods:

Two hundred E. coli strains, isolated from different clinical specimens were used. ESBL-producing E. coli were detected by determining susceptibility to ceftazidime, cefotaxime, and cefpodoxime with the phenotypic confirmatory test (PCT). PCR analysis was employed to detect the qnrA, qnrB, qnrS, bla_TEM, and bla_SHV genes.

Results:

Eighty-six (43%) isolates were ciprofloxacin-resistant. The PCT identified 85 (42.5%) of 200 E. coli isolates as ESBL-producing. The bla_TEM, bla_SHV, qnrA, qnrB, and qnrS gene were found in 65 (76.47%), 23 (27%), 63 (31%), 34 (17%), and 14 (7%) isolates, respectively.

Conclusions:

The high prevalence of quinolone resistance genes, which indicates antibiotic resistance, in the Imam Reza Hospital of Mashhad is a major concern. Hence, the antibiotics prescription policy should be revised, and infection control measures should be improved.

A qPCR and multiplex pyrosequencing assay combined with automated data processing for rapid and unambiguous detection of ESBL-producers Enterobacteriaceae

Rapid and specific detection of extended-spectrum β-lactamase-producing (ESBL) bacteria is crucial both for timely antibiotic therapy when treating infected patients as well as for appropriate infection control measures aimed at curbing the spread of ESBL-producing isolates. Whereas a variety of phenotypic methods are currently available for ESBL detection, they remain time consuming and sometimes difficult to interpret while being also affected by a lack of sensitivity and specificity. Considering the longer turnaround time (TAT) of susceptibility testing and culture results, DNA-based ESBL identification would be a valuable surrogate for phenotypic-based methods. Putative ESBL-positive Enterobacteriaceae isolates (n = 330) from clinical specimen were prospectively collected in Bulgaria, Romania and Democratic Republic of Congo and tested in this study. All isolates were assessed for ESBL-production by the E-test method and those giving undetermined ESBL status were re-tested using the combination disk test. A genotypic assay successively combining qPCR detection of blaCTX-M, blaTEM and blaSHV genes with a multiplex pyrosequencing of blaTEM and blaSHV genes was developed in order to detect the most common ESBL-associated TEM and SHV single nucleotides polymorphisms, irrespective of their plasmid and/or chromosomal location. This assay was applied on all Enterobacteriaceae isolates (n = 330). Phenotypic and genotypic results matched in 324/330 (98.2%). Accordingly, real-time PCR combined with multiplex pyrosequencing appears to be a reliable and easy-to-perform assay with high-throughput identification and fast TAT (~5 h).

Extended-spectrum β-lactamase infections during pregnancy: a growing threat

Extended-spectrum β-lactamases (ESBLs) are rapidly evolving plasmid transferrable enzymes that confer unique patterns of antibiotic resistance on various bacterial species. Such organisms pose special challenges to laboratory identification, as well as antibiotic selection, administration, and follow-up. Although such infections are increasingly common in the obstetric population, issues surrounding ESBLs are not widely recognized by practicing obstetricians, and controversies exist regarding diagnosis and management. This article provides the practitioner with a summary of clinically pertinent information that will assist in the proper care of pregnant patients with ESBL infection.

Aminoglycoside therapy for childhood urinary tract infection due to extended-spectrum β-lactamase-producing Escherichia coli or Klebsiella pneumoniae

BACKGROUND

The rate of urinary tract infections (UTIs) due to extended-spectrum β-lactamase (ESBL)-producing bacterial strains requiring carbapenem therapy has been increasing in children. This study was conducted to evaluate the effect of non-carbapenem antibiotic therapy on childhood UTIs caused by ESBL-producing Escherichia coli or Klebsiella pneumoniae.

METHODS

Medical records of children diagnosed with febrile UTIs due to E. coli or K. pneumoniae between 2010 and 2014 were retrospectively reviewed. The enrolled children were divided into two groups: the ESBL group and the non-ESBL group. Clinical characteristics and therapeutic responses were compared between the two groups.

RESULTS

A total of 211 episodes of UTI (204 caused by E. coli; seven caused by K. pneumoniae) were identified in 205 children. Twenty-two (10.4 %) episodes were categorized into the ESBL group. There was no significant difference in the type of antibiotic administered between the two groups. No carbapenems were administered; however, aminoglycosides were administered for 79.1 % of the total episodes. Although empirical antibiotics were appropriate for more episodes in the non-ESBL group compared with the ESBL group (100.0 % vs. 90.9 %, p = 0.011), there were no significant differences in the frequency of defervescence, bacterial eradication from the urine, acute pyelonephritis and vesicoureteral reflux or fever duration between the two groups.

CONCLUSIONS

Non-carbapenem antibiotics showed favourable therapeutic effects on childhood UTIs caused by ESBL-producing strains. Aminoglycosides can be an alternative to carbapenems in such cases.

Efficacy of humanized high-dose meropenem, cefepime, and levofloxacin against Enterobacteriaceae isolates producing Verona integron-encoded metallo-β-lactamase (VIM) in a murine thigh infection model

We aimed to describe the in vivo activity of humanized pharmacokinetic exposures of meropenem and comparators against Verona integron-encoded metallo-β-lactamase (MBL) (VIM)-producing Enterobacteriaceae in a murine model. Levofloxacin activity was predicted by its MIC, and cefepime activity displayed variability, whereas meropenem produced a >1 log CFU reduction against all isolates despite high MICs indicative of resistance. Our results suggest that despite in vitro resistance, high-dose meropenem may be a possible option against infections caused by Enterobacteriaceae producing MBL-type carbapenemases.

Prevalence of β-Lactamase Producing Escherichia coli from Retail Meat in Turkey

Extended spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (pAmpC) producing Escherichia coli have been shown to be present in humans and animals representing a significant problem worldwide. This study aimed to search the presence of ESBL and/or AmpC-producing E. coli in retail meats (chicken and beef) in Turkey. A total of 88 β-lactamase-producing E. coli were isolated from chicken (n = 81/100) and beef meat (n = 7/100) samples and their susceptibility to several antimicrobials were tested using disc diffusion method. E. coli isolates were further characterized for their phylogenetic groups. β-Lactamase encoding (blaTEM , blaSHV , blaOXA , blaCTX-M , and blaAmpC ) and quinolone resistance genes (qnrA, qnrB, qnrS, qepA, and acc(6')-Ib-cr) were also secreened by polymerase chain reaction (PCR). However, in regard to β-lactamase genes, 84 of 88 isolates were positive for blaCTX-M-1 (n = 39), blaCTX-M-3 (n = 5), blaCTX-M-15 (n = 4), blaTEM-1b (n = 2), blaSHV-12 (n = 1), blaCTX-M-1 /blaTEM-1b (n = 10), blaCTX-M-1 /blaTEM-1b /blaSHV-5 (n = 1), blaCTX-M-1 /blaCMY-2 (n = 1) and blaTEM-1b /blaCMY-2 (n = 6), blaCTX-M-15 /blaSHV-12 (n = 1), blaCTX-M-15 /blaTEM-1b (n = 1), blaTEM-1b /blaSHV-12 (n = 1), and blaCMY-2 (n = 12) genes. Resistance to cefuroxime (75.6% and 85.7%), nalidixic acid (89% and 85.7%), tetracycline (91.4% and 100%), streptomycin (40.2% and 100%), and trimethoprim-sulfamethoxazole (36.6% and 85.7%) was observed among strains isolated from chicken and beef, respectively. However, all isolates were found to be susceptible to amikacin, imipenem, and cefepime. Resistance to ampicillin and cefoxitin was significantly linked to blaCMY-2 gene, while there was a significant correlation between CTX-M type ESBL and antimicrobial resistance to cefuroxime and streptomycin (P < 0.05). The results of this study suggest that raw chicken retail meats are highly contaminated with ESBL-producing E. coli implementing a great risk to human health in Turkey.

Bacterial temporal dynamics enable optimal design of antibiotic treatment

There is a critical need to better use existing antibiotics due to the urgent threat of antibiotic resistant bacteria coupled with the reduced effort in developing new antibiotics. β-lactam antibiotics represent one of the most commonly used classes of antibiotics to treat a broad spectrum of Gram-positive and -negative bacterial pathogens. However, the rise of extended spectrum β-lactamase (ESBL) producing bacteria has limited the use of β-lactams. Due to the concern of complex drug responses, many β-lactams are typically ruled out if ESBL-producing pathogens are detected, even if these pathogens test as susceptible to some β-lactams. Using quantitative modeling, we show that β-lactams could still effectively treat pathogens producing low or moderate levels of ESBLs when administered properly. We further develop a metric to guide the design of a dosing protocol to optimize treatment efficiency for any antibiotic-pathogen combination. Ultimately, optimized dosing protocols could allow reintroduction of a repertoire of first-line antibiotics with improved treatment outcomes and preserve last-resort antibiotics.

Antibiotic resistance is a growing problem that the World Health Organization describes as “one of the top three threats to global health.” To date, bacteria have developed resistance to all antibiotics used in clinical settings. Unfortunately, the evolution of antibiotic resistant bacteria is accelerating, as antibiotics continue to be misused and overused. As the antibiotic pipeline is drying up, it becomes increasingly critical to utilize the antibiotics already on the market more effectively. The key to designing better regimens lies in the ability to predict how bacteria will respond to a particular antibiotic treatment. Because of this, we need a simple metric that characterizes this pathogen-antibiotic interaction that can be easily measured and used to design dosing protocols that will effectively clear an infection. To help guide the design of effective protocols, we use quantitative modeling to develop a metric that is easy to measure and quantifies the pathogen-antibiotic interaction. Through optimized antibiotic regimens, our strategy could extend the use of first-line antibiotics, improve treatment outcome, and preserve last-resort antibiotics.

Factors that affect transfer of the IncI1 β-lactam resistance plasmid pESBL-283 between E. coli strains

The spread of antibiotic resistant bacteria worldwide presents a major health threat to human health care that results in therapy failure and increasing costs. The transfer of resistance conferring plasmids by conjugation is a major route by which resistance genes disseminate at the intra- and interspecies level. High similarities between resistance genes identified in foodborne and hospital-acquired pathogens suggest transmission of resistance conferring and transferrable mobile elements through the food chain, either as part of intact strains, or through transfer of plasmids from foodborne to human strains. To study the factors that affect the rate of plasmid transfer, the transmission of an extended-spectrum β-lactamase (ESBL) plasmid from a foodborne Escherichia coli strain to the β-lactam sensitive E. coli MG1655 strain was documented as a function of simulated environmental factors. The foodborne E. coli isolate used as donor carried a CTX-M-1 harboring IncI1 plasmid that confers resistance to β-lactam antibiotics. Cell density, energy availability and growth rate were identified as factors that affect plasmid transfer efficiency. Transfer rates were highest in the absence of the antibiotic, with almost every acceptor cell picking up the plasmid. Raising the antibiotic concentrations above the minimum inhibitory concentration (MIC) resulted in reduced transfer rates, but also selected for the plasmid carrying donor and recombinant strains. Based on the mutational pattern of transconjugant cells, a common mechanism is proposed which compensates for fitness costs due to plasmid carriage by reducing other cell functions. Reducing potential fitness costs due to maintenance and expression of the plasmid could contribute to persistence of resistance genes in the environment even without antibiotic pressure. Taken together, the results identify factors that drive the spread and persistence of resistance conferring plasmids in natural isolates and shows how these can contribute to transmission of resistance genes through the food chain.

The molecular basis of β-lactamase production in Gram-negative bacteria from Saudi Arabia

Resistance to β-lactams among Gram-negative bacteria is a worldwide issue. Increased prevalence of extended-spectrum β-lactamase (ESBL)-producers and the dissemination of carbapenem-resistance genes are particularly concerning. ESBL-producing strains are common in the Kingdom of Saudi Arabia, particularly among the Enterobacteriaceae, and carbapenem resistance is on the increase, especially among the non-fermenters. β-lactamase production is a major mechanism of resistance to these agents and although β-lactamase-producing strains have been documented in the Kingdom, relatively few reports characterized the molecular basis of this production. Nevertheless, available data suggest that CTX-M (CTX-M-15 in particular) is the predominant ESBL in the Enterobacteriaceae, with SHV also being prevalent in Klebsiella pneumoniae. Carbapenem resistance in the latter is mainly due to OXA-48 and NDM-1. In Pseudomonas aeruginosa, VEB-like enzymes are the most common ESBLs, and VIM is the prevalent metallo-β-lactamase. OXA-10 extended-spectrum enzymes are also frequent. PER and GES ESBLs have been reported in Acinetobacter baumannii, and oxacillinases (OXA-23 in particular) are the dominant carbapanamases in this species.

Extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae bacteremia in febrile neutropenic children

This retrospective study was conducted to evaluate clinical outcomes of bacteremia caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae and their antibiotic susceptibilities in febrile neutropenic children. Clinical characteristics, prognosis, and antibiotic susceptibilities were reviewed and compared between febrile neutropenic children with bacteremia caused by ESBL-producing and non-ESBL-producing E. coli and K. pneumoniae. A total of 61 episodes of E. coli and K. pneumoniae bacteremia, including 21 episodes (34.4%) due to ESBL-producing strains, were diagnosed. There was no significant factor associated with bacteremia by ESBL-producing strains. Empirical antibiotics were appropriate in 85.7% of the ESBL group and 95.0% of the non-ESBL group. In the entire study population, seven deaths (11.5%), including three deaths (4.9%) due to E. coli and K. pneumoniae bacteremia, occurred. The complication and mortality rates were not significantly different between the two groups. Antibiotic susceptibility rates were significantly lower in the ESBL group than in the non-ESBL group in most antibiotics. Although 52.4% and 66.7% of the ESBL-producing isolates were susceptible to piperacillin/tazobactam and cefepime, respectively, 96.7% of all the isolates and 90.5% of the ESBL-producing isolates were susceptible to piperacillin/tazobactam or cefepime in combination with aminoglycoside. In conclusion, the ESBL group did not show a significantly unfavorable outcome, and empirical therapy with piperacillin/tazobactam or cefepime in combination with aminoglycoside might be more useful for febrile neutropenic children, instead of β-lactam monotherapy in institutions with high prevalence of ESBL-producing E. coli and K. pneumoniae.

Resistance to extended-spectrum β-lactamases in Salmonella from a broiler supply Chain

The prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae varies worldwide, however, the incidence of ESBL-producing environmental Salmonella isolates is increasing. Salmonella is still one of the most important pathogens that occur in the poultry supply chain. Therefore, this study analyzed the susceptibility of Salmonella isolates collected from a poultry supply chain to β-lactam antibiotics, and examined the phenotypes of the isolates based on enzyme-inducible AmpC β-lactamase analysis. All analysis of the putative positive isolates in the current study confirmed that 27.02% (77/285 analysis) of all ESBL tests realized with the isolates produced a profile of resistance consistent with β-lactamase production. All isolates of S. Minnesota serotype had ESBL phenotype. Aztreonam resistance was the least common amongst the Salmonella isolates, followed by ceftazidime. The presence of inducible chromosomal ESBL was detected in 14 different isolates of the 19 serotypes investigated. These results are very indicatives of the presence of ESBL genes in Salmonella isolates from a broiler supply chain, reaffirming the growing global problem of ESBL resistance.

Antimicrobial profiles of bacterial clinical isolates from the Gabonese National Laboratory of Public Health: data from routine activity

BACKGROUND

The present study is one of the first to provide a picture of antimicrobial resistance for a range of bacteria and antimicrobial classes in Gabon, Central Africa.

METHODS

During the year 2010, 146 urine cytology, 143 blood cultures, 107 vaginal swabs, 23 urethral swabs, and 18 other culture examinations were positives. All isolates were tested for antibiotic sensitivity.

RESULTS

Four hundred thirty-seven microorganisms were isolated: 210 enterobacteria, 166 staphylococci, 38 streptococci, 14 Acinetobacter, and nine Stenotrophomonas. Of the Klebsiella isolates, 18% and 30% were found to be resistant to selected third-generation cephalosporins (3CG) and fourth-generation cephalosporins (4CG), respectively. Sixty-seven percent of Escherichia coli isolates were resistant to amoxicillin with clavulanic acid. Between 3% and 30% of E. coli isolates were resistant to selected 3CG. All Enterobacter cloacae isolates were sensitive to imipenem. Resistance to quinolones/fluoroquinolones was seen in 21-50% of E. coli isolates. Twenty-six percent of E. cloacae showed resistance to ceftazidime and 37% to cefotaxime. The resistance rate to quinolones ranged between 58% and 78%. Thirty-two percent of Staphylococcus isolates were resistant to gentamicin. Low resistance rates to teicoplanin (2-4%) were observed. Thirty-seven percent of isolated Staphylococcus aureus and 61% of isolated Staphylococcus saprophyticus were resistant to both penicillin G and oxacillin. Streptococcus isolates had low resistance rates to erythromycin, ceftriaxone, and ciprofloxacin (5%, 7%, and 14%, respectively) and were highly resistant to tetracycline, gentamicin, and sulfamethoxazole-trimethoprim (92%, 91%, and 62%, respectively).

CONCLUSIONS

The antimicrobial resistance profiles seen here are of concern. To control the spread of drug-resistant bacteria, clinicians should be cognizant of their local antimicrobial resistance patterns.

High cell selectivity and low-level antibacterial resistance of designed amphiphilic peptide G(IIKK)(3)I-NH(2)

On the basis of cell cultures involving bacterial strains (Escherichia coli 5α and Bacillus subtilis 168) and a mammalian cell line (NIH 3T3), the potent antibacterial activity and distinct selectivity from designed amphiphilic peptides G(IIKK)nI-NH2 (n = 2-4) have been demonstrated. This work extends these studies to multidrug resistant pathogens (ESBL-producing E. coli) and primary human cells (HDFa), followed by the in vivo mouse model investigation of ESBL-producing bacterial infection. G(IIKK)3I-NH2 exhibits high antibacterial activity against the pathogenic strain both in vitro and in vivo while displaying low toxicity toward the primary cells and the mice. Peptide molecules can kill bacteria by selectively interacting with bacterial membranes, causing structural disruptions. Furthermore, multidrug resistant ESBL-producing bacteria do not develop resistance after multiple treatments with G(IIKK)3I-NH2. The high cellular selectivity, low toxicity toward mammalian hosts and noninducing bacterial resistance indicate great potential for developing the peptides as anti-infection agents.

Nosocomial extended-spectrum beta-lactamase-producing Klebsiella pneumoniae bacteremia in hemodialysis patients and the implications for antibiotic therapy

BACKGROUND

In the face of increasing treatment options for extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) hemodialysis (HD) access-related bacteremia, the difference in clinical effectiveness between ertapenem and flomoxef remains unclear. We conducted this retrospective study to determine their efficacies and treatment outcomes.

METHODS

Patients on maintenance HD with fistula-, graft-, or catheter-related ESBL-Kp bacteremia were enrolled. Data related to clinical features and antibiotic treatments were collected. Outcome was determined by mortality resulting from bacteremia during the 14-day period after the collection of the first positive blood culture for flomoxef-susceptible ESBL-Kp.

RESULTS

The 64 patients studied had severe septicemia as determined by the Pitt bacteremia score; 50% (32/64) were in the intensive care unit (ICU) at the time of bacteremia. Old age (>65 years; 57.8%), malnutrition (albumin<3.5g/dl; 92.2%), a history of severe illnesses (defined by shock, intubation, or ICU stay; 82.5%), and prolonged hospitalization prior to the onset of bacteremia (>30 days; 75%) were also highly prevalent. The study population comprised nine fistula-, 10 graft-, and 45 HD catheter-related bacteremia cases, and the mortality rate was high (38/64, 59.4%). The mortality rate was significantly higher in the flomoxef treatment group than in the ertapenem treatment group (22/30, 73% vs. 16/34, 47%, p<0.05). Among patients with catheter-related bacteremia, multivariate analyses revealed that flomoxef use (odds ratio (OR) 2.52, 95% confidence interval (CI) 1.34-35.17) and Pitt bacteremia score (OR 4.37, 95% CI 1.28-5.26) were independently associated with mortality.

CONCLUSIONS

In accordance with our previous study, our results have demonstrated the inferiority of flomoxef to carbapenems in the treatment of HD access-related ESBL-Kp bacteremia and provide an insight into the possibility of using ertapenem rather than flomoxef as an initial or de-escalating therapy for infections caused by ESBL-producing bacteria.

Fluorogenic probes with substitutions at the 2 and 7 positions of cephalosporin are highly BlaC-specific for rapid Mycobacterium tuberculosis detection

Current methods for the detection of Mycobacterium tuberculosis (Mtb) are either time consuming or require expensive instruments and are thus are not suitable for point-of-care diagnosis. The design, synthesis, and evaluation of fluorogenic probes with high specificity for BlaC, a biomarker expressed by Mtb, are described. The fluorogenic probe CDG-3 is based on cephalosporin with substitutions at the 2 and 7 positions and it demonstrates over 120,000-fold selectivity for BlaC over TEM-1 Bla, the most common β-lactamase. CDG-3 can detect 10 colony-forming units of the attenuated Mycobacterium bovis strain BCG in human sputum in the presence of high levels of contaminating β-lactamases expressed by other clinically prevalent bacterial strains. In a trial with 50 clinical samples, CDG-3 detected tuberculosis with 90% sensitivity and 73% specificity relative to Mtb culture within one hour, thus demonstrating its potential as a low-cost point-of-care test for use in resource-limited areas.

Molecular features of community-associated extended-spectrum-β-lactamase-producing Escherichia coli strains in the United States

We characterized 30 community-associated extended-spectrum-β-lactamase-producing Escherichia coli isolates collected from five hospitals in the United States. Nineteen sequence types were identified. All sequence type 131 (ST131) isolates had the fimH30 allele. IncFII-FIA-FIB was the most common replicon type among the blaCTX-M-carrying plasmids, followed by IncFII-FIA and IncA/C. Restriction analysis of the IncFII-FIA-FIB and IncFII-FIA plasmids yielded related profiles for plasmids originating from different hospitals. The plasmids containing blaCTX-M or blaSHV were stably maintained after serial passages.

Carbapenems and piperacillin/tazobactam for the treatment of bacteremia caused by extended-spectrum β-lactamase-producing Proteus mirabilis

This study was intended to delineate the role of carbapenems and piperacillin/tazobactam in treating bacteremia caused by extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis. We performed a multicenter and retrospective study of the patients with ESBL-producing P. mirabilis bacteremia. The outcomes of the patients treated by piperacillin/tazobactam or a carbapenem for at least 48 hours and the MICs of the prescribed drugs for these isolates were analyzed. Forty-seven patients with available clinical data were included. The overall 30-day mortality rate was 29.8%. All available isolates (n = 44) were susceptible to ertapenem, meropenem, and doripenem, and 95.6% were susceptible to piperacillin/tazobactam; however, only 11.4% of the isolates were susceptible to imipenem. Among the 3 patients infected with isolates exhibiting non-susceptibility to imipenem (MIC ≥2 mg/L) who were treated with imipenem, none died within 28 days. The 30-day (14.3% versus 23.1%, P = 0.65) or in-hospital (19.1% versus 30.8%, P = 0.68) mortality rate of 21 patients treated by a carbapenem was lower than that of 13 treated by piperacillin/tazobactam. However, among those treated by piperacillin/tazobactam, the mortality rate of those infected by the isolates with lower piperacillin/tazobactam MICs (≤0.5/4 mg/L) was lower than that of the isolates with MICs of ≥1/4 mg/L (0%, 0/7 versus 60%, 3/5; P = 0.045). ESBL-producing P. mirabilis bacteremia is associated with significant mortality, and carbapenem therapy could be regarded as the drugs of choice. The role of piperacillin/tazobactam, especially for the infections due to the isolates with an MIC ≤0.5/4 mg/L, warrants more clinical studies.

A multicenter prospective study of infections related morbidity and mortality in cirrhosis of liver

BACKGROUND AND AIMS

Infections are a common and serious complication among patients with cirrhosis. We assessed the epidemiology, risk factors, and clinical consequences of bacterial infections in cirrhotic patients.

METHODS

In this multicenter prospective study, all patients with cirrhosis of liver with different infections were analyzed. Infections were classified as community-acquired (CA), healthcare-associated (HCA), or hospital-acquired (HA). Site of infection and characteristics of bacteria were recorded; effect on liver function and 30-day survival were evaluated.

RESULTS

One hundred and six out of 420 (25 %) patients with cirrhosis of liver had infection. Infection rate among indoor patients was 37.5 % (92/245) and among outdoor patients was 8 % (14/175). Out of 106 patients, CA, HCA, and HA were seen in 19.8 %, 50 %, and 30.2 %, respectively. Spontaneous bacterial peritonitis (31.1 %), urinary tract infections (22.6 %), and pneumonia and cellulitis (11.3 % each) were common infections. Gram-negative bacteria (54 %) were more common than Gram-positive cocci (46 %). Multidrug resistant (MDR) organisms were seen in 41.7 % of patients. Most of the MDR organisms were seen in HCA and HA patients. The degree of liver impairment was significantly more severe in patients with infection. Independent predictor of infection was high Child-Turcott-Pugh (CTP) class (p = 0.006, Child B vs. A (odds ratio (OR) 3.04 95 % CI = 1.63 to 5.68) and Child C vs. A (OR 4.17 95 % CI = 2.12 to 8.19). Overall in-hospital mortality was 7.6 %. Patients with infection had increased mortality at 30-day follow up compared to those without infection (23.5 % vs. 2.2 %; p<0.001).

CONCLUSIONS

Infections are one of the important causes of morbidity and mortality in patients with cirrhosis of liver. The most frequent infections are HCA and HA. Infection predisposes to deterioration of liver function and increases mortality. Cirrhotic patients should be monitored closely for infections especially those with Child class B and C.

Successful control of a neonatal outbreak caused mainly by ST20 multidrug-resistant SHV-5-producing Klebsiella pneumoniae, Greece

Background

Extended spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) infection can cause significant morbidity and mortality in neonates. We investigated a nosocomial ESBL-Kp outbreak in a neonatal intensive care unit (NICU) of the University Hospital of Larissa (UHL), Central Greece.

Methods

A total of sixty-four ESBL-Kp were studied; twenty six isolates were recovered from the NICU and were compared with thirty-eight randomly selected isolates from different wards of the hospital during the period March- December 2012. All isolates were characterized by antimicrobial susceptibility testing, ESBL-production by double-disk synergy test, molecular typing using BOX-PCR, whereas selected isolates were further characterized by beta lactamase and virulence gene content, multilocus sequence typing and phylogenetic analysis. All neonates affected by ESBL-Kp were put under strict contact isolation, along with appropriate infection control measures.

Results

The outbreak strain of ST20 multidrug-resistant SHV-5-producing K. pneumoniae was identified in all infected (n = 13) and three colonized neonates. A novel ST (ST1114) was also identified among SHV-5 producers (n = 10) recovered from nine colonized infants, but it was not related with ST20. Both STs were identified only in the NICU and not in other wards of the hospital. No ESBL-Kp were isolated from the hands of the nursing staff and the environment. Although we were not able to identify the source of the outbreak, no ESBL-Kp were isolated in the NICU after this period and we assumed that the outbreak was successfully controlled. All neonates received parenteral nutrition and most of them were delivered by caesarean section and showed low gestational age (<32 weeks) and low birth weights (<1500 g).

Conclusion

According to our knowledge, this is the first description of an outbreak of multidrug-resistant SHV-5 producing K. pneumoniae assigned to ST20.

Extended-spectrum-beta-lactamase producing bacteria related urinary tract infection in renal transplant recipients and effect on allograft function

Background

Urinary tract infection (UTI) is a well-recognized early complication in renal transplant recipients (RTR) and can have significant bearing on their outcome. The recent rise in incidence of extended spectrum beta lactamase (ESBL) producing bacteria causing UTI among RTR poses new and significant challenges in terms of management and outcome. Our aim is to analyze the effect of ESBL producing bacteria causing UTI in these patients and its impact on allograft function.

Methods

We reviewed the medical records of 147 RTR who were followed at a tertiary care hospital affiliated transplant center between January 2007 and May 2013 and noted five RTR who developed episodes of ESBL producing bacteria related UTI during follow up. Multiple patient characteristics including demographics, immunosuppression, recurrences, allograft function and outcome were analyzed.

Results

Five patients (3.4%) out of 147 had ESBL producing bacteria related UTI. We found all patients to be above 60 years of age, with three out of five being females, and all five patients had diabetes mellitus. We identified a total of 37 episodes of UTI among these five patients during this period. Two of these patients had elevated creatinine values during the episodes of UTI and three of them developed bacteremia. Of the five patients, four of them had a favorable outcome except for one patient who developed persistent allograft dysfunction.

Conclusion

RTR are at a higher risk for developing ESBL producing bacteria associated UTI. Early diagnosis along with appropriate and judicious use of antibiotics will ensure long term success in allograft and patient outcome.

Resource competition may lead to effective treatment of antibiotic resistant infections

Drug resistance is a common problem in the fight against infectious diseases. Recent studies have shown conditions (which we call antiR) that select against resistant strains. However, no specific drug administration strategies based on this property exist yet. Here, we mathematically compare growth of resistant versus sensitive strains under different treatments (no drugs, antibiotic, and antiR), and show how a precisely timed combination of treatments may help defeat resistant strains. Our analysis is based on a previously developed model of infection and immunity in which a costly plasmid confers antibiotic resistance. As expected, antibiotic treatment increases the frequency of the resistant strain, while the plasmid cost causes a reduction of resistance in the absence of antibiotic selection. Our analysis suggests that this reduction occurs under competition for limited resources. Based on this model, we estimate treatment schedules that would lead to a complete elimination of both sensitive and resistant strains. In particular, we derive an analytical expression for the rate of resistance loss, and hence for the time necessary to turn a resistant infection into sensitive (tclear). This time depends on the experimentally measurable rates of pathogen division, growth and plasmid loss. Finally, we estimated tclear for a specific case, using available empirical data, and found that resistance may be lost up to 15 times faster under antiR treatment when compared to a no treatment regime. This strategy may be particularly suitable to treat chronic infection. Finally, our analysis suggests that accounting explicitly for a resistance-decaying rate may drastically change predicted outcomes in host-population models.

Prevalence of extended spectrum beta lactamase producing Escherichia coli and Klebsiella pneumoniae urinary isolates in a tertiary care hospital in Kathmandu, Nepal

BACKGROUND

Escherichia coli and Klebsiella pneumoniae are the major bacterial pathogens being isolated and reported from mid stream urine (MSU) specimens, globally. These uropathogens are mostly implicated as the major extended spectrum beta-lactamase (ESBL) producers, severely limiting the therapeutic management in cases of urinary tract infections. Limited studies had been reported from Nepal investigating the ESBL producers among uropathogens. This study was designed to assess the prevalence of ESBL producing E.coli and K. pneumoniae in urinary isolates at a centrally located major tertiary care hospital in Kathmandu valley, Nepal.

METHODS

Between September 2011 and May 2012, during the nine months period, 6308 MSU specimens were collected aseptically from the same number of clinically suspected patients of urinary tract infections. The samples were cultured on MacConkey agar and blood agar. The isolates with significant bacteriuria (105 CFU / ml) were identified based on standard laboratory procedures. Antimicrobial susceptibility tests were carried out using various antimicrobial discs alongwith ceftriaxone on E.coli and K. pneumoniae isolates by Kirby Bauer disc diffusion method as per the recommendations of CLSI. On initial screening with ceftriaxone (30 μg) disc showing resistance was then confirmed for ESBL production by phenotypic confirmatory disc diffusion test (PCDDT) using ceftazidime (30 ug) and ceftazidime + clavulanic acid (30 μg + 10ug) disc as per guidelines of CLSI (2011).

RESULTS

Out of a total of 6308 MSU specimens investigated for significant bacteriuria, E.coli isolates were 444 (7.04%) and K.pneuminiae were 145 (2.3%) making a total of 589 (9.34%). Initial screening with ceftriaxone disc revealed 155 isolates of E.coli and 70 isolates of K.pneumoniae to be resistant. Further testing by PCDDT method showed 60/444 (=13.51%) of E. coli and 24/145 (=16.55%) of K. pneumoniae isolates to be confirmed ESBL producers. These ESBL - producer uropathogens showed high degree of resistance to ceftriaxone (100.0%), amoxycillin, fluoroquinolones and co-trimoxazole.

CONCLUSION

An emerging and moderately high prevalence of ESBL-producing E. coli and K. pneumoniae was observed and confirmed in the urinary isolates investigated. It is essential to have a regular and routine monitoring of ESBL producing clinical isolates in laboratory practice.

Prevalence and antibiogram of Extended Spectrum β-Lactamase (ESBL) producing Gram negative bacilli and further molecular characterization of ESBL producing Escherichia coli and Klebsiella spp

BACKGROUND AND OBJECTIVES

Resistance to a wide variety of common antimicrobials has made the proliferation of Extended spectrum β-lactmase (ESBL) producing strains a serious global health concern that has complicated treatment strategies. The high proportion of ESBL producers among the Enterobacteriaceae and the complex molecular epidemiology with diverse types of ESBL genes are alarming. This study was undertaken to identify ESBL production in various Gram negative bacilli isolated and to further characterize ESBL producers among Escherichia coli and Klebsiella spp by PCR, which were initially screened by phenotypic method.

MATERIALS AND METHODS

A total of 722 isolates of Gram negative bacilli were isolated. Presence of ESBL positivity was detected using the double disk synergy test (DDST). Their antibiogram was studied. PCR analysis for β-lactamase (bla) genes of the family TEM, SHV and CTX-M was also carried out using designed primers in 20 ESBL isolates each of Escherichia coli and Klebsiella spp.

RESULTS

Among 722 Gram negative bacilli isolated 379 (52.49%) were ESBL producers. The major source of ESBL producers were respiratory tract samples, highest ESBL production was observed in Klebsiella sp. (67.04%). Resistance to multiple classes of antibiotics was observed among ESBL producers. Among ESBL producing genes prevalence of bla-CTX-M (82.5%) was highest, followed by bla-TEM (67.5%) and bla-SHV (57.5%) in the present study. The frequency of ESBL producing strains among clinical isolates has been steadily increasing. Advance drug resistance surveillance and molecular characteristics of ESBL isolates is necessary to guide the appropriate and judicious antibiotic use.

Epidemiology and risk factors of community-onset urinary tract infection caused by extended-spectrum β-lactamase-producing Enterobacteriaceae in a medical center in Taiwan: a prospective cohort study

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing pathogens have been increasingly identified in community-onset urinary tract infection (UTI). This study was conducted to determine the epidemiology and risk factors of community-onset UTI caused by ESBL-producing pathogens, and to determine the correlation of antimicrobial resistance with ESBL detected by phenotypic and genotypic methods.

METHODS

The study was conducted from December 2010 to January 2012. Patients with community-onset UTI caused by Enterobacteriaceae were enrolled from the emergency department. The production of ESBL was determined by the phenotypic method (using the combined disk test) or by the genotypic method (using polymerase chain reaction detection). The patients' medical records were reviewed and risk factors were analyzed by multivariate analysis.

RESULTS

A total of 376 patients were enrolled and 393 isolates from urine culture were analyzed. Escherichia coli was the most commonly isolated species (259/393 isolates; 65.9%), followed by Klebsiella pneumoniae (42/393 isolates; 10.7%). Fifty-three (13.5%) isolates were phenotypically positive for ESBL production. Nine (2.3%) isolates were phenotypically positive for both ESBL and AmpC β-lactamase (AmpC) production. Nasogastric tube placement [odds ratio (OR) 2.230; 95% confidence interval (CI) 1.244-3.997; p = 0.007] and hospitalization within the previous 3 months (OR 2.567, 95% CI 1.448-4.551, p = 0.001) were independently associated with the acquisition of ESBL-producing pathogens in community-onset UTI. The ESBL phenotype had a better correlation with resistance to third-generation cephalosporins, compared to the ESBL-positive genotype.

CONCLUSION

In our study, nasogastric tube placement and hospitalization within the previous 3 months were significantly associated with the acquisition of ESBL-producing pathogens in community-onset UTI.

Pollution impacts on bacterioplankton diversity in a tropical urban coastal lagoon system

Despite a great number of published studies addressing estuarine, freshwater and marine bacterial diversity, few have examined urban coastal lagoons in tropical habitats. There is an increasing interest in monitoring opportunistic pathogens as well as indigenous microbial community members in these water bodies by current molecular and microbiological approaches. In this work, bacterial isolates were obtained through selective plate dilution methods to evaluate antibiotic resistances. In addition, 16S rRNA gene libraries were prepared from environmental waters and mixed cultures grown in BHI medium inoculated with Jacarepaguá lagoon waters. Denaturing gradient gel electrophoresis (DGGE) analyses showed distinct community profiles between environmental communities from each studied site and their cultured counterparts. A total of 497 bacterial sequences were analyzed by MOTHUR, yielding 245 operational taxonomic units (OTUs) grouped at 97% similarity. CCA diagrams showcased how several environmental variables affect the distribution of 18 bacterial orders throughout the three distinct habitats. UniFrac metrics and Venn diagrams revealed that bacterial communities retrieved through each experimental approach were significantly different and that only one OTU, closely related to Vibrio cholerae, was shared between them. Potentially pathogenic bacteria were isolated from most sampled environments, fifty percent of which showed antibiotic resistance.

Antibiotic Resistance Mechanisms in the Intensive Care Unit

Antibiotic resistance is increasingly recognised as a major threat to global health, with few new antimicrobial agents in development. The intensive care unit provides a unique environment for the growth and spread of drug-resistant organisms. Knowledge of the pathogenesis and mechanisms of resistance of drug-resistant organisms provides a conceptual framework which underpins the clinical manifestation of infections caused by these organisms, and is crucial for the intensivist to understand. Particular importance lies in the prevention of infection and the control of drug-resistant pathogens. The major resistance mechanisms of these organisms will be highlighted, focusing on specific gram-positive (meticillin-resistant Staphylococcus aureus and glycopeptide-resistant Enterococci), gram-negative ( Pseudomonas aeruginosa, Acinetobacter baumannii and multi-drug resistant Enterobacteriaceae) organisms, and then placed in historical and clinical context.

Antibiotic resistance amongst healthcare-associated pathogens in China

The People's Republic of China, commonly known as China, comprises approximately one-fifth of the world's population. Because of the expanding size and density of its population and the frequent interaction of people with animals, China is a hotspot for the emergence and spread of new microbial threats and is a major contributor to the worldwide infectious disease burden. In recent years, the emergence and rapid spread of severe acute respiratory syndrome (SARS) generated considerable interest in the Chinese healthcare system and its infection control and prevention measures. This review examines antibiotic misuse and the status of antibiotic resistance in the Chinese healthcare system. China has high rates of antibiotic resistance driven by misuse of these agents in a healthcare system that provides strong incentives for overprescribing and in a country where self-medication is common. Tuberculosis remains a serious problem in China, with a high prevalence of multidrug-resistant and extensively drug-resistant strains. Drug resistance amongst nosocomial bacteria has been on a rapid upward trend with a strong inclination towards multidrug resistance. There is a need for effective infection prevention and control measures and strict use of antibiotics in China to control the rise and spread of antibiotic resistance in the country.

Discrepancy between effects of carbapenems and flomoxef in treating nosocomial hemodialysis access-related bacteremia secondary to extended spectrum beta-lactamase producing Klebsiella pneumoniae in patients on maintenance hemodialysis

Background

Hemodialysis (HD) patients are susceptible to extended spectrum beta-lactamase (ESBL)-producing bacterial infections. Because the optimal treatment and clinical significance of ESBL-producing Klebsiella pneumoniae (ESBL-Kp) HD access-related bacteremia remain unclear, we conducted this retrospective study to determine the clinical outcomes of patients treated with either flomoxef or a carbapenem.

Methods

The eligibility criterion was fistula or graft- or catheter- related ESBL-Kp bacteremia in patients on maintenance HD. The clinical characteristics and antibiotic management were analyzed. Outcome was determined by mortality resulting from bacteremia during the 14‐day period after the first positive blood culture for flomoxef-susceptible ESBL-Kp.

Results

The 57 patients studied were predominantly elderly, malnourished, with a history of severe illnesses and broad-spectrum antibiotic use before the onset of bacteremia, and with severe septicemia as determined by the Pitt bacteremia score (PBS). The study population comprised 7 fistula, 8 graft, and 42 HD catheter-related bacteremia (CRB) cases, and the mortality rate was high (36/57, 63.2%) in these 57 patients. Of 42 patients with CRB, those in the deceased group (27/42, 64.3%) had significantly lower levels of serum albumin, longer prior hospital stay and duration of catheter-dependent HD, and higher PBS than patients in the survived group. Failure to receive effective antibiotics (flomoxef or a carbapenem) within 5 days after onset of bacteremia and treatment with flomoxef both significantly contributed to higher mortality. Multivariate analyses revealed that flomoxef use, PBS, and catheter-dependent HD >30 days were independently associated with increased mortality (OR, 3.52; 95% CI, 1.19–58.17, OR, 2.92; 95% CI, 1.36–6.26 and OR, 5.73; 95% CI, 1.21–63.2, respectively).

Conclusions

Considering the high mortality rate, ESBL-Kp should be recognized as a possible pathogen in patients on maintenance HD at high risk of acquiring HD access infections associated with ESBL-producing bacteria. Carbapenems rather than flomoxef should be the therapy of choice in these critically vulnerable patients.

Liver abscesses in adult patients with and without diabetes mellitus: an analysis of the clinical characteristics, features of the causative pathogens, outcomes and predictors of fatality: a report based on a large population, retrospective study in China

In China, there are four types of liver abscesses (LAs) that meet the clinical criteria. Pyogenic liver abscesses (PLAs) and amoebic liver abscesses (ALAs) are two of the most common types of abscesses, followed by fungal liver abscesses (FLAs) and hydatid secondary liver abscesses (HsLAs). Diabetes mellitus (DM) is associated with the development of PLAs. However, there is a lack of population-based studies that have evaluated the underlying relationship between LAs (mainly PLAs and FLAs) and DM. We conducted a retrospective study based on a large population to identify the potential differences and factors that affect the mortality of PLA patients in DM and non-DM groups. Our results revealed that the prevalence of DM is 44.3% (158/357) in PLA patients and 35.3% (18/51) in FLA patients. Compared with the non-DM patients, statistically significant differences were found in DM patients according to symptomatology, clinical manifestations, laboratory findings, microbiological characteristics, antimicrobial resistance, clinical treatments and outcomes in relation to mortality. In addition, the status of antibiotic resistance to E. coli and K. pneumoniae, which were isolated from the patient samples, is severe in the area in which the study was conducted. Regarding the treatment of PLAs, our study indicated that broad-spectrum antimicrobial therapy and drug combinations should be recommended and initiated before the pathogens are cultured and identified. In the clinic, therapies that combine percutaneous drainage with antibiotics and surgery with antibiotics are the two most useful strategies for treating an LA. These two combined treatments resulted in satisfactory cure rates. In the DM and non-DM groups, the cure rates for percutaneous drainage with antibiotics were 90.3% and 92.0%, respectively, and the cure rates for surgery with antibiotics were 93.9% and 95.2%, respectively.

Decreased aztreonam susceptibility among Pseudomonas aeruginosa isolates from hospital effluent treatment system and clinical samples

The aim of this study was to evaluate the antimicrobial resistance patterns of Pseudomonas aeruginosa isolates from hospital wastewater treatment system (HWTS) and clinical specimens in a hospital of Rio de Janeiro city, Brazil. Forty-three isolates obtained from four of the five steps of the HWTS (n = 27) and clinical samples (n = 16) from patients were analyzed regarding their susceptibility profiles to 12 antibiotics. Clinical isolates exhibited higher resistance profiles to antibiotics than wastewater isolates. However, out of 27 isolates from sewage, 62.9% showed decreased susceptibility to aztreonam while 50% of clinical isolates were resistant to this antibiotic. Isolates were not detected at the chlorination stage but they were obtained from the following stage of the treatment revealing the capacity of regrowth after chlorinated sewage effluent. To our knowledge, this is the first study reporting decreased aztreonam susceptibility among P. aeruginosa isolates from a hospital wastewater treatment system. Further investigations are being conducted by our laboratory including a larger sampling program in order to obtain more data.

Detection of Extended Spectrum β-lactamase Production Among Uropathogens

Background:

Detection of extended spectrum β-lactamase (ESBL) production among uropathogens is an important marker of endemicity.

Aim:

Intervention of this endemic transmission is important for the control of initial outbreak of ESBL producing organisms in a hospital or specialized unit of hospital.

Materials and Methods:

During the study period of one and a half months, 1,551 urine samples were processed for significant bacteriuria. Two hundred gram negative bacterial isolates were tested for ESBL production. Antimicrobial sensitivity pattern was ascertained for ESBL producing isolates.

Results:

ESBL production was seen in 36% of isolates. All the isolates were multidrug resistant with uniform sensitivity to imipenem.

Conclusion:

This study reveals the significant prevalence of ESBL producing organisms in this north Indian tertiary care hospital. Constant revision of antibiotic policies with infection control interventions is suggested.