Epidemiology of Nosocomial Infections Due to Gram-Negative Bacilli: Aspects Relevant to Development and Use of Vaccines

Stamm, Walter E.; Martin, S. M.; Bennett, John V.

doi:10.1093/infdis/136.supplement.s151

Cited by 173 publications

(68 citation statements)

References 6 publications

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“…A number of studies have shown that hospital-acquired infections are responsible for approximately 10% of the patients (Stamn et al, 1977, Mayon-White et al, 1988, Meers et al, 1990. This risk of nosocomial infection is further escalated by the increasing prevalence of antibiotic-resistant pathogens such as methicillin (oxacillin)-resistant S. aureus (MRSA) and vancomycin-resistant Enterococci (VRE) among Gram-positive organisms, and multi-drug resistant (MDR) Pseudomonas aeruginosa and Acinetobacter among Gramnegative organisms.…”

Section: Introductionmentioning

confidence: 99%

Airborne and Surface-Bound Microbial Contamination in Two Intensive Care Units of a Medical Center in Central Taiwan

Huang

Shi

Chen

et al. 2013

Aerosol Air Qual. Res.

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Samples of airborne and surface-bound microbial contamination were taken in two intensive care units of a large-scale medical center. Microbial analyses included total bacterial and fungal loads, as well as the four bacterial species of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii. Among the 114 surface samples taken from seven designated surface locations of room and equipment for each patient, P. aeruginosa was the most frequently detected (19.3%) and most abundant (mean count: 4.18 cfu/plate) bacterium, whereas the respirator represented the most heavily contaminated surface location in both total pathogenic bacteria colony counts (272 cfu) and frequency of positive detection (38.2%). P. aeruginosa also represented the most frequently detected (39.1%, n = 46) and abundant (11.52 ± 17.16 cfu/m 3 ) bacterium in the air samples (n = 46), and was the only bacterium exhibiting a positive correlation of the mean counts between air and surface samples. The data analysis results further suggested a higher value of relative risk among the infected patients in the presence of the pathogens as compared to those in the absence of them, although the evidence of a of correlation for the individual bacterial species between the environmental samples and infected patients was inconclusive. This study also found that the mean airborne counts and the detection frequencies of these bacteria after patient visitation periods were higher than those before visitation, and that the installation of local air ionizers did not lead to any discernible differences in total bacterial and fungal concentrations.

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Section: Introductionmentioning

confidence: 99%

Airborne and Surface-Bound Microbial Contamination in Two Intensive Care Units of a Medical Center in Central Taiwan

Huang

Shi

Chen

et al. 2013

Aerosol Air Qual. Res.

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“…In many cases, the bacteria that cause these infections are resistant to multiple antibiotics, and thus, they pose a serious threat to the safety and proper functioning of health care facilities. E. coli is one of the most common causes of nosocomial UTIs (including ABU) (17,36). Many ABU E. coli strains are phylogenetically related to virulent uropathogenic E. coli (UPEC) strains, with the differences in virulence properties being multifactorial and associated with various combinations of genotypic and phenotypic factors (26,49).…”

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confidence: 99%

Escherichia coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Properties

et al. 2010

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Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli being responsible for >80% of all cases. Asymptomatic bacteriuria (ABU) occurs when bacteria colonize the urinary tract without causing clinical symptoms and can affect both catheterized patients (catheterassociated ABU [CA-ABU]) and noncatheterized patients. Here, we compared the virulence properties of a collection of ABU and CA-ABU nosocomial E. coli isolates in terms of antibiotic resistance, phylogenetic grouping, specific UTI-associated virulence genes, hemagglutination characteristics, and biofilm formation. CA-ABU isolates were similar to ABU isolates with regard to the majority of these characteristics; exceptions were that CA-ABU isolates had a higher prevalence of the polysaccharide capsule marker genes kpsMT II and kpsMT K1, while more ABU strains were capable of mannose-resistant hemagglutination. To examine biofilm growth in detail, we performed a global gene expression analysis with two CA-ABU strains that formed a strong biofilm and that possessed a limited adhesin repertoire. The gene expression profile of the CA-ABU strains during biofilm growth showed considerable overlap with that previously described for the prototype ABU E. coli strain, 83972. This is the first global gene expression analysis of E. coli CA-ABU strains. Overall, our data suggest that nosocomial ABU and CA-ABU E. coli isolates possess similar virulence profiles.Urinary tract infections (UTIs) are among the most common infectious diseases acquired in nosocomial settings. UTIs may be symptomatic (e.g., cystitis and pyelonephritis) or asymptomatic. Asymptomatic bacteriuria (ABU) is an asymptomatic carrier state that resembles commensalism. ABU patients often carry Ͼ105 CFU/ml of urine of a single bacterial strain without symptoms; in nosocomial settings, ABU frequently occurs in both catheterized and noncatheterized patients. In catheterized patients, the risk of bacteriuria is estimated to be 5 to 10% per day (46), and most patients with an indwelling urinary catheter for 30 days or longer develop bacteriuria (35). ABU in catheterized and noncatheterized patients may also lead to symptomatic UTIs, with patients experiencing fever, suprapubic tenderness, and, in some cases, bacteremia, acute pyelonephritis, and death (16,45).ABU is caused by a range of Gram-negative and Grampositive organisms, including Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Providencia stuartii, Staphylococcus epidermidis, and Enterococcus faecalis (16,46). In many cases, the bacteria that cause these infections are resistant to multiple antibiotics, and thus, they pose a serious threat to the safety and proper functioning of health care facilities. E. coli is one of the most common causes of nosocomial UTIs (including ABU) (17, 36). Many ABU E. coli strains are phylogenetically related to virulent uropathogenic E. coli (UPEC) strains, with the differences in virulence properties being multifactorial and associated with various co...

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“…If these speculations are substantiated, an understanding of how the capsule and the O-specific antigen modulate host response could have significant therapeutic implications. The potential use of biologic modulators directed against the host response, as well as approaches based on inactivating bacterial components (e.g., surface polysaccharides) in attempts to modify sepsis syndromes, could be developed.Enteric gram-negative bacilli are a group of pathogens that are capable of causing severe, life-threatening pneumonia (8,24,26). Despite the availability of active antimicrobial agents, there has been little improvement in outcome from this infection over the last 10 to 15 years.…”

mentioning

confidence: 99%

“…Enteric gram-negative bacilli are a group of pathogens that are capable of causing severe, life-threatening pneumonia (8,24,26). Despite the availability of active antimicrobial agents, there has been little improvement in outcome from this infection over the last 10 to 15 years.…”

mentioning

confidence: 99%

Capsular Polysaccharide and O-Specific Antigen Divergently Modulate Pulmonary Neutrophil Influx in an Escherichia coli Model of Gram-Negative Pneumonitis in Rats

et al. 2000

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Enteric gram-negative bacilli cause a severe, often life-threatening pneumonia. An improved understanding of the pathogenesis of this infection may lead to improved treatment. Nearly all of the responsible gramnegative bacilli possess capsular polysaccharides and/or an O-specific antigen as part of their lipopolysaccharide (LPS). We hypothesized that these surface polysaccharides may modulate the pulmonary host response. To investigate this, a rat pneumonitis model was used, and pulmonary neutrophil influx, a critical aspect of host defense, was measured. To assess for the effect of the capsule and O-specific antigen on this host response, three proven, isogenic derivatives that are deficient in capsular polysaccharide alone (CP9.137), the O-specific antigen moiety of the LPS alone (CP921), and both the capsular polysaccharide and O-specific antigen (CP923), as well as their wild-type parent (CP9), were used as challenge strains at various intratracheal challenge inocula (CI). Total lung myeloperoxidase (MPO), a surrogate marker for neutrophils, was measured for 15 h post-bacterial challenge. To determine the effect of capsule and the O-specific antigen on the measured MPO levels, a mathematical model was developed and used to describe the MPO levels as a function of time for each CI of each of the four strains. The results from this analysis demonstrated that in the absence of the K54 capsule, 80.7 times the CI is necessary to achieve the same maximum MPO level relative to K54 positive strains (P < 0.0001). In contrast, a diametric effect was observed in the absence of the O-specific antigen, where 0.13 times the CI was necessary to achieve the same maximum MPO level relative to O4-positive strains (P ‫؍‬ 0.0032). No interactive effect was observed between the capsule and the O-specific antigen. These findings demonstrate that these surface polysaccharides modulate pulmonary neutrophil influx and suggest that the K54 capsular polysaccharide is a proinflammatory mediator and that the O4-specific antigen attenuates the proinflammatory response. If these speculations are substantiated, an understanding of how the capsule and the O-specific antigen modulate host response could have significant therapeutic implications. The potential use of biologic modulators directed against the host response, as well as approaches based on inactivating bacterial components (e.g., surface polysaccharides) in attempts to modify sepsis syndromes, could be developed.Enteric gram-negative bacilli are a group of pathogens that are capable of causing severe, life-threatening pneumonia (8,24,26). Despite the availability of active antimicrobial agents, there has been little improvement in outcome from this infection over the last 10 to 15 years. As a result, this syndrome continues to cause significant morbidity and mortality and strongly contributes to the economic burden of our national health care system. An improved understanding of the pathogenesis of this infection may result in improved treatment or prevention of infection.The imp...

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Epidemiology of Nosocomial Infections Due to Gram-Negative Bacilli: Aspects Relevant to Development and Use of Vaccines

Cited by 173 publications

References 6 publications

Airborne and Surface-Bound Microbial Contamination in Two Intensive Care Units of a Medical Center in Central Taiwan

Airborne and Surface-Bound Microbial Contamination in Two Intensive Care Units of a Medical Center in Central Taiwan

Escherichia coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Properties

Capsular Polysaccharide and O-Specific Antigen Divergently Modulate Pulmonary Neutrophil Influx in an Escherichia coli Model of Gram-Negative Pneumonitis in Rats

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