Risk factors for nosocomial infections caused by gram-negative bacilli. The Hellenic Antibiotic Resistance Study Group

Adequacy of empiric gram-negative coverage for septic patients at an academic medical center

BACKGROUND

Gram-negative organisms (GNOs) have increasing resistance rates to levofloxacin at Virginia Commonwealth University Health System (VCUHS), where levofloxacin is the most common agent added to provide double coverage of gram-negative infections. The goal of this study was to determine the adequacy of empiric gram-negative coverage for septic patients at our institution.

METHODS

A retrospective review of patients admitted to VCUHS, from January 1, 2014, to December 31, 2014, with a diagnosis of sepsis, severe sepsis, or septic shock and documented infection, was performed to determine the adequacy of various empiric antibiotic combinations.

RESULTS

Of 219 patients who met the inclusion criteria, 56% of patients received monotherapy and 21% of patients received combination therapy (2 antibiotics) covering GNOs. GNOs (84%) were susceptible to piperacillin-tazobactam. When used in combination with cefepime and meropenem, levofloxacin did not increase coverage. However, levofloxacin provided an 8% increase in coverage and gentamicin provided an additional 13% increase in coverage, respectively, when used in combination with piperacillin-tazobactam.

CONCLUSIONS

Among septic patients at VCUHS, gentamicin provided increased gram-negative coverage when compared with levofloxacin. Although susceptibility to piperacillin-tazobactam alone was relatively low, the combination of piperacillin-tazobactam and gentamicin provided nearly equivalent coverage to meropenem and gentamicin.

An individual-based model of transmission of resistant bacteria in a veterinary teaching hospital

Veterinary nosocomial infections caused by antibiotic resistant bacteria cause increased morbidity, higher cost and length of treatment and increased zoonotic risk because of the difficulty in treating them. In this study, an individual-based model was developed to investigate the effects of movements of canine patients among ten areas (transmission points) within a veterinary teaching hospital, and the effects of these movements on transmission of antibiotic susceptible and resistant pathogens. The model simulates contamination of transmission points, healthcare workers, and patients as well as the effects of decontamination of transmission points, disinfection of healthcare workers, and antibiotic treatments of canine patients. The model was parameterized using data obtained from hospital records, information obtained by interviews with hospital staff, and the published literature. The model suggested that transmission resulting from contact with healthcare workers was common, and that certain transmission points (housing wards, diagnostics room, and the intensive care unit) presented higher risk for transmission than others (lobby and surgery). Sensitivity analyses using a range of parameter values demonstrated that the risk of acquisition of colonization by resistant pathogens decreased with shorter patient hospital stays (P<0.0001), more frequent decontamination of transmission points and disinfection of healthcare workers (P<0.0001) and better compliance of healthcare workers with hygiene practices (P<0.0001). More frequent decontamination of heavily trafficked transmission points was especially effective at reducing transmission of the model pathogen.

Profile of microorganisms and antimicrobial resistance at a tertiary care referral burn centre in Iran: emergence of Citrobacter freundii as a common microorganism

Infection and antimicrobial resistance are important issues in severe burn. The aims of this prospective study were to investigate the profile of microorganisms and resistance to antimicrobial agents in a tertiary referral burn centre; 113 people aged >10 years, with partial- or full-thickness burns, were included in the study. A total of 733 samples including 275 swabs, 164 tissue biopsies, 258 urine samples, 26 blood samples and 10 sputum samples were collected, from which 124 microorganisms were isolated. Pseudomonas aeruginosa and Citrobacter spp were the most prevalent isolates (57.3% and 35.5%, respectively); 95.5% of Citrobacter. isolates were Citrobacter freundii. Antibiogram results obtained from 15 antimicrobial agents demonstrated that imipenem was the most effective agent against P. aeruginosa, followed by ciprofloxacin and piperacillin/tazobactam (67.9%, 43% and 37.5% sensitive, respectively). At least 60% of all Citrobacter isolates were sensitive to various antimicrobial agents, the highest sensitivity being obtained by ceftazidime and cefepime (81.6% and 78.4%, respectively). Sensitivity of P. aeruginosa isolates to the agents of each antimicrobial class was significantly different (p<0.001). The incidence of C. freundii and the resistance of P. aeruginosa to anti-pseudomonas agents were exceptionally high.

Intensive care unit-acquired urinary tract infections in patients admitted with sepsis: etiology, risk factors, and patterns of antimicrobial resistance

OBJECTIVES

The objective of the present study was to evaluate the etiology, risk factors, and patterns of antimicrobial resistance of intensive care unit (ICU)-acquired urinary tract infections (UTIs) in patients admitted with sepsis.

METHODS

In this observational study, 100 septic patients hospitalized in a general ICU were selected. Demographic, clinical, and outcome data were obtained by chart review. Antibiotic resistance/susceptibility was determined using the minimal inhibitory concentration (MIC) technique.

RESULTS

A UTI was present in 28 (28%) patients; the male to female ratio was 19:9 and the mean age of the patients was 58.71+/-19.45 years. From the total of 28 isolates, 27 were resistant to ciprofloxacin, 23 to amikacin, 27 to meropenem, 28 to cefepime, 26 to ceftazidime, and 27 to ceftriaxone.

CONCLUSIONS

On the basis of our results, the rate of multidrug-resistant UTIs may be very high in some ICUs in patients admitted with sepsis. This antimicrobial susceptibility/resistance should be determined, and a special antimicrobial treatment protocol should be planned based on the results for each ICU. The use of antibiotics for treating UTIs should be guided only through this protocol because of the different spectra of pathogens and susceptibility patterns in each ICU.

Development of antimicrobial drug resistance in rectalEscherichia coliisolates from dogs hospitalized in an intensive care unit

OBJECTIVE

To determine whether duration of hospitalization in the intensive care unit (ICU) of a veterinary teaching hospital was associated with prevalence of antimicrobial resistance among rectal Escherichia coli isolates from dogs, whether antimicrobial treatment was associated with prevalence of antimicrobial resistance, and whether there were associations among antimicrobial drugs to which isolates were resistant.

DESIGN

Prospective observational study.

ANIMALS

116 dogs hospitalized in an ICU for >or= 3 days.

PROCEDURES

Rectal swab specimens were obtained every 3 days and submitted for bacterial culture for E coli. Isolates were tested for susceptibility to 12 antimicrobial agents by means of disk diffusion.

RESULTS

For each additional day that a dog was hospitalized in the ICU, the odds of being colonized with an E coli isolate resistant to 1 or more of the 12 antimicrobials tested increased by a factor of 1.5, independent of antimicrobial treatment. Dogs that were treated with enrofloxacin were 25.6 times as likely to be colonized by a quinolone-resistant E coli strain as were dogs that did not receive any antimicrobials. Significant correlations were found for resistance to agents in the extended-spectrum cephalosporin group and the quinolone group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that the proportion of rectal E coli isolates obtained from dogs housed for >or= 3 days in a veterinary teaching hospital ICU that were resistant to antimicrobial agents increased as the duration of hospitalization in the ICU increased. Thus, ICU hospitalization time should be as short as possible to prevent development of antimicrobial resistance among rectal E coli isolates.

A resistência bacteriana no contexto da infecção hospitalar

Este artigo aborda alguns aspectos do impacto da resistência bacteriana no contexto da infecção hospitalar. Alerta sobre o importante papel dos profissionais de saúde no controle da infecção hospitalar e do grave problema do uso indiscriminado de antibióticos que tem provocado uma pressão seletiva sobre as bactérias do ambiente hospitalar tornando-as multiresistentes

Epidemiological risk factors for isolation of ceftriaxone-resistant versus -susceptible citrobacter freundii in hospitalized patients

Antimicrobial resistance is an emerging problem among nosocomial bacteria. Risk factors for the recovery of ceftriaxone-resistant (CRCF) or -susceptible (CSCF) Citrobacter freundii in clinical cultures from hospitalized patients were determined by using a case-case-control study design. CRCF was isolated from 43 patients (case group 1) and CSCF was isolated from 87 patients (case group 2) over a 3-year period. Risk factors for CRCF were exposure to imipenem (odds ratio [OR], 7.5; 95% confidence interval [CI], 1.2 to 45.4), broad-spectrum cephalosporins (OR, 6.9; 95% CI, 1.8 to 26.7), vancomycin (OR, 3.0; 95% CI, 1.2 to 7.4), or piperacillin-tazobactam (OR, 2.6; 95% CI, 1.1 to 6.2), as well as hospital length of stay >or=1 week (OR, 3.6; 95% CI, 1.3 to 10.2) and intensive care unit (ICU) stay (OR, 2.6; 95% CI, 1.1 to 6.2). Risk factors for CSCF were peripheral vascular disease (OR, 23.2; 95% CI, 4.3 to 124.6), AIDS (OR, 9.5; 95% CI, 1.6 to 55.5), cerebrovascular disease (OR, 4.2; 95% CI, 1.6 to 10.8), and ICU stay (OR, 3.1; 95% CI, 1.8 to 5.4).

PDMS-based polyurethanes with MPEG grafts: mechanical properties, bacterial repellency, and release behavior of rifampicin

PDMS-based polyurethanes (PUs) grafted with monomethoxy poly(ethylene glycol) (MPEG) were synthesized to develop a coating material for urinary catheters with a silicone surface for minimizing urinary tract infections. MPEG was grafted on PDMS-based PUs by two methods depending on the PU synthetic routes: esterification and allophanate reactions. It was confirmed from mechanical characterization that an increase of the hard segment amount enhanced the ultimate strength and Young's modulus, while reducing elongation at the end-points. The incorporation of MPEG in PDMS-based PUs induced a decrease in tensile strength and Young's modulus, and increased elongation at the break point due to its high flexibility. When hydrated in distilled water, mechanical properties of all PUs synthesized in this study deteriorated due to water absorption. It was evident from the bacterial adhesion test that PDMS-based PUs showed moderate resistance to adhesion of E. coli on their surfaces compared to Pellethane, while the incorporation of MPEG significantly enhanced repellency to bacteria, including E. coli and S. epidermidis. We also studied the release behavior of an antibiotic drug, rifampicin, from the polymeric devices fabricated by solvent evaporation. Although rifampicin is hydrophilic and soluble in pH 7.4 phosphate buffer, it showed a sustained release over 45 days from PDMS-based PUs with MPEG that were grafted on ethylene glycol residues by allophanate reaction. This release characteristic was predominantly influenced by a hydrogen bond interaction between the polymers and rifampicin, which was confirmed through an ATR-IR study. This may imply that the specific interaction is responsible for the delayed release. Considering the mechanical properties, morphologies of drug-incorporated polymeric matrices, and drug release behaviors, PDMS-based PU with MPEG that were grafted on ethylene glycol (a chain extender) residues by allophanate reaction showed better material properties for uretharal catheter coating pusposes in order to minimize urinary tract infections.

An enzyme immunoassay to determine the levels of specific antibodies toward bacterial surface antigens in human immunoglobulin preparations and blood serum

Human polyvalent intravenous immunoglobulin (IVIG) preparations are used as a complementary aid to the proper antimicrobial treatment of severely septic patients in intensive care units (ICUs) and/or as a prophylactic agent to immunocompromised hosts, particularly prone to bacterial infections. There is skepticism about the usefulness of IVIGs since it is not known whether their administration ensures the enhancement of humoral immune responses by providing a sufficient amount of specific antibodies towards the specified bacterial pathogen to be treated. In this report, a simple and reproducible enzyme-linked immunosorbent assay for determining the content of specific antibodies against bacterial surface antigens in commercially available IVIG preparations is described. The method is also easily applied to determine the amount of bacterial antibodies in blood serum. The levels of specific antibodies toward gram positive and negative pathogenic isolates often encountered in ICUs were estimated in two IVIG (Sandoglobulin and Gamimmune) preparations. Significant differences regarding the content of antibodies to certain clinically bacterial isolates were identified not only between the two IVIG preparations tested, but also among various lots from each IVIG preparation. No significant variation (P < or = 0.001) among the bottles derived from the same lot was determined in both preparations. The variation in the levels of specific antibodies in IVIG preparations may be attributed to differences between the donor pools as well as the manufacturing procedure. Application of the method to patients with primary immune deficiencies showed that infusion of highly reactive IVIG preparations enhanced significantly their humoral response toward various pathogens. The results of this study suggest that the content determination of pathogen-specific antibodies in IVIG preparations before administration may be of great importance for treating bacterial infections.

Risk factors for hospital-acquired urinary tract infection in a large English teaching hospital: a case-control study

About 10% of patients in hospital develop a hospital-acquired infection (HAI); the most commonly affected site is the urinary tract. Many studies have examined risk factors for HAI but few have adjusted for confounding and interaction. We performed a prospective case-control study on six acute wards of a busy English teaching hospital to assess risk factors for hospital-acquired urinary tract infection (HAUTI). Over a 2-year period, 136 cases were identified (2.8% of all patient episodes) along with 408 controls. Multiple logistic regression revealed that female sex, increased length of stay, elective admission, surgical operation, and transurethral and repeated intermittent catheterization were all significant independent risk factors for HAUTI. However, specialty of admission was also a significant risk factor when added to the model and, under these conditions, only length of stay and catheterization also remained significant. We detected significant interactions suggesting that the risk of HAUTI is maximal among women undergoing elective surgery, especially those who are catheterized; however, the overall risk of HAUTI among patients admitted electively was greater than for patients admitted as emergencies.

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.

Bacterial resistance to ciprofloxacin in Greece: results from the National Electronic Surveillance System. Greek Network for the Surveillance of Antimicrobial Resistance

According to 1997 susceptibility data from the National Electronic System for the Surveillance of Antimicrobial Resistance, Greece has high rates of ciprofloxacin resistance. For most species, the frequency of ciprofloxacin-resistant isolates (from highest to lowest, by patient setting) was as follows: intensive care unit > surgical > medical > outpatient. Most ciprofloxacin-resistant strains were multidrug resistant.