Pseudomonas aeruginosa and the oropharyngeal ecosystem of tube-fed patients

A score to predict Pseudomonas aeruginosa infection in older patients with community-acquired pneumonia

BACKGROUND

In Thailand, the incidence of community-acquired pseudomonal pneumonia among 60- to 65-year-olds ranges from 10.90% to 15.51%, with a mortality rate of up to 19.00%. Antipseudomonal agents should be selected as an empirical treatment for elderly patients at high risk for developing this infection. The purpose of this study was to identify risk factors and develop a risk predictor for Pseudomonas aeruginosa infection in older adults with community-acquired pneumonia (CAP).

METHODS

A retrospective data collection from an electronic database involved the elderly hospitalized patients with P. aeruginosa- and non-P. aeruginosa-causing CAP, admitted between January 1, 2016, and June 30, 2021. Risk factors for P. aeruginosa infection were analysed using logistic regression, and the instrument was developed by scoring each risk factor based on the beta coefficient and evaluating discrimination and calibration using the area under the receiver operating characteristic curve (AuROC) and observed versus predicted probability (E/O) ratio.

RESULTS

The inclusion criteria were met by 81 and 104 elderly patients diagnosed with CAP caused by P. aeruginosa and non-P. aeruginosa, respectively. Nasogastric (NG) tube feeding (odd ratios; OR = 40.68), bronchiectasis (B) (OR = 4.13), immunocompromised condition (I) (OR = 3.76), and other chronic respiratory illnesses (r) such as atelectasis, pulmonary fibrosis, and lung bleb (OR = 2.61) were the specific risk factors for infection with P. aeruginosa. The "60-B-r-I-NG" risk score was named after the 4 abbreviated risk variables and found to have good predicative capability (AuROC = 0.77) and accuracy comparable to or near true P. aeruginosa infection (E/O = 1). People who scored at least two should receive empirically antipseudomonal medication.

CONCLUSIONS

NG tube feeding before admission, bronchiectasis, immunocompromisation, atelectasis, pulmonary fibrosis and lung bleb were risk factors for pseudomonal CAP in the elderly. The 60-B-r-I-NG was developed for predicting P. aeruginosa infection with a high degree of accuracy, equal to or comparable to the existing P. aeruginosa infection. Antipseudomonal agents may be started in patients who are at least 60 years old and have a score of at least 2 in order to lower mortality and promote the appropriate use of these medications.

Oral colonisation by antimicrobial-resistant Gram-negative bacteria among long-term care facility residents: prevalence, risk factors, and molecular epidemiology

Background

For residents of long-term care facilities (LTCFs), antimicrobial-resistant bacteria (ARB) are a risk factor, yet their oral colonisation, potentially leading to aspiration pneumonia, remains unclear. This study was undertaken to survey the prevalence, phenotypic characteristics, and molecular epidemiology of antimicrobial-resistant Gram-negative bacteria in the oral cavity of LTCF residents, and to analyse the risk factors for such carriers.

Methods

This study involved 98 residents of a LTCF in Hiroshima City, Japan, aged between 55 and 101 years. Oropharyngeal swabs were collected and plated on screening media for ESBL-producing and carbapenem-resistant bacteria; isolates were identified and tested for antibiotic susceptibility; biofilm formation was tested in vitro; identification of epidemic clones were pre-determined by PCR; resistance genes, sequence types, and whole-genome comparison of strains were conducted using draft genome sequences. Demographic data and clinical characterisations were collected and risk factors analysed.

Results

Fifty-four strains from 38% of the residents grew on screening media and comprised predominantly of Acinetobacter spp. (35%), Enterobacteriaceae spp. (22%), and Pseudomonas spp. (19%). All Escherichia coli isolates carried CTX-M-9 group and belonged to the phylogroup B2, O25:H4 ST131 fimH30 lineage. Six Acinetobacter baumannii isolates presented identical molecular characteristics and revealed more biofilm production than the others, strongly suggesting their clonal lineage. One Acinetobacter ursingii isolate displayed extensive resistance to various ß-lactams due to multiple acquired resistance genes. One Pseudomonas aeruginosa isolate showed exceptional resistance to all ß-lactams including carbapenems, aminoglycosides, and a new quinolone, showing a multidrug-resistant Pseudomonas aeruginosa (MDRP) phenotype and remarkable biofilm formation. Genome sequence analysis revealed this isolate was the bla_IMP-1-positive clone ST235 in Japan. Strokes (cerebral infarction or cerebral haemorrhage) and percutaneous endoscopic gastrostomy tubes were recognised as risk factors for oral colonisation by ARB in the LTCF residents.

Conclusions

ARB, as defined by growth on screening agar plates, which carried mobile resistance genes or elements or conferred high biofilm formation, were already prevalent in the oral cavity of LTCF residents. Health-care workers involved in oral care should be aware of antimicrobial resistance and pay special attention to transmission prevention and infection control measures to diminish ARB or mobile resistance elements dissemination in LTCFs.

Competing Morbidities In Advanced Head And Neck Squamous Cell Carcinoma Concurrent Chemoradiotherapy: A Strong Implication Of A Multidisciplinary Team Approach

Concurrent chemoradiotherapy (CCRT) is the standard approach for the treatment of locally advanced head and neck squamous cell carcinoma. Despite its undisputed advantages, CCRT is associated with acute and late toxicities, leading to unfavorable implications (eg, unplanned interruptions and noncancer-related mortality). The former prolongs the overall treatment time leading to a detrimental effect on tumor control. The latter consists of several noncancer morbidities arising from treatment-related toxicities, identifying a new pathway in cancer fate. This pathway has been termed noncancer mortality or competing mortality and consists of a series of treatment-competing morbidities, which nullify all therapeutic efforts aimed at curing these patients. The management of patients with head and neck squamous cell carcinoma who experience treatment-related toxicities is complex and requires expertise in oncological treatment as well as supportive care. The optimal management of these patients should start with knowledge regarding the most important competing morbidities developing during all phases of the disease (ie, from diagnosis to follow-up) to minimize treatment interruptions, ensure appropriate psychological support, and achieve the best oncological result. The purpose of the present review is to analyze the most important competing morbidities due to patient’s condition at baseline and CCRT, which could result in noncancer mortality. A multidisciplinary team approach is strongly required in the management of this disease.

Risk factors for carbapenem-resistant Klebsiella pneumoniae infection: A meta-analysis

OBJECTIVES

Rates of nosocomial infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) have increased. A meta-analysis was conducted to explore risk factors for CRKP infection in order to provide a theoretical basis for reducing the CRKP infection rate and actively preventing CRKP infection.

METHODS

Online databases, including PubMed, EMBASE, OVID, ClinicalKey, CNKI, CBM, Wanfang Database and CHKD, were searched from inception up to 31 October 2018 for articles regarding risk factors for CRKP infection. Relevant articles were retrieved, supplemented by retrospective and manual search literature. RevMan 5.3 software was used for statistical analysis.

RESULTS

A total of 30 articles comprising 5075 cases were included in the study, of which 24 were in English and 6 were in Chinese. The results showed that age, sex and diabetes mellitus were not associated with CRKP infection. The odds ratio (95% confidence interval) of risk factors for CRKP infection were as follows: immunosuppression, 1.47 (1.14-1.90); ICU admission, 3.25 (2.36-4.47); antibiotic exposure, 2.53 (1.56-4.11); carbapenem exposure, 3.99 (2.86-5.56); quinolone exposure, 1.75 (1.38-2.22); glycopeptide exposure, 3.08 (1.93-4.91); β‑lactam/β‑lactamase inhibitor (BL/BLI) exposure, 2.28 (1.37-3.80); surgery, 1.59 (1.08-2.34); mechanical ventilation, 2.91 (1.96-4.31); central venous catheterisation, 2.93 (2.00-4.28); indwelling catheter, 2.62 (1.65-4.17); and nasogastric intubation, 2.38 (1.22-4.62).

CONCLUSION

Immunosuppression, ICU admission, antibiotic exposure (including carbapenems, quinolones, glycopeptides and BL/BLIs), surgery, mechanical ventilation, central venous catheterisation, indwelling catheter and nasogastric intubation were identified as risk factors for CRKP infection and should to be considered in clinical practice.

Advancements and Potential Applications of Microfluidic Approaches—A Review

A micro-level technique so-called “microfluidic technology or simply microfluidic” has gained a special place as a powerful tool in bioengineering and biomedical engineering research due to its core advantages in modern science and engineering. Microfluidic technology has played a substantial role in numerous applications with special reference to bioscience, biomedical and biotechnological research. It has facilitated noteworthy development in various sectors of bio-research and upsurges the efficacy of research at the molecular level, in recent years. Microfluidic technology can manipulate sample volumes with precise control outside cellular microenvironment, at micro-level. Thus, enable the reduction of discrepancies between in vivo and in vitro environments and reduce the overall reaction time and cost. In this review, we discuss various integrations of microfluidic technologies into biotechnology and its paradigmatic significance in bio-research, supporting mechanical and chemical in vitro cellular microenvironment. Furthermore, specific innovations related to the application of microfluidics to advance microbial life, solitary and co-cultures along with a multiple-type cell culturing, cellular communications, cellular interactions, and population dynamics are also discussed.

Gut biofilm forming bacteria in inflammatory bowel disease

Inflammatory bowel disease (IBD) symbolizes a group of intestinal disorders in which prolonged inflammation occur in the digestive tract (esophagus, large intestine, small intestine mouth, stomach). Both genetic and environmental factors (infections, stress, diet) are involved in the development of IBD. As we know that bacteria are found in the intestinal mucosa of human and clinical observations revealed bacterial biofilms associated with patients of IBD. Various factors and microbes are found to play an essential role in biofilm formation and mucosal colonization during IBD. Biofilm formation in the digestive tract is dependent on an extracellular matrix synthesized by the bacteria and it has an adverse effect on the immune response of the host. There is no satisfactory and safe treatment option for IBD. Therefore, the current research aims to disrupt biofilm in IBD and concentrates predominantly on improving the drug. Here, we review the literature on bacterial biofilm and IBD to gather new knowledge on the current understanding of biofilm formation in IBD, host immune deregulation and dysbiosis in IBD, molecular mechanism, bacteria involved in biofilm formation, current and future regimen. It is urgently required to plan new ways to control and eradicate bacteria in biofilms that will open up novel diagnostic and therapeutic avenues for IBD. This article includes the mechanism of signaling molecules with respect to the biofilm-related genes as well as the diagnostic methods and new technologies involved in the treatment of IBD.

Proteomic Response of Pseudomonas aeruginosa PAO1 Adhering to Solid Surfaces

Pseudomonas aeruginosa is a pathogenic micro-organism responsible for many hospital-acquired infections. It is able to adhere to solid surfaces and develop an immobilized community or so-called biofilm. Many studies have been focusing on the use of specific materials to prevent the formation of these biofilms, but the reactivity of the bacteria in contact to surfaces remains unknown. The aim of this study was to evaluate the impact of the abiotic surface on the physiology of adherent bacteria. Three different materials, stainless steel (SS), glass (G), and polystyrene (PS) that were relevant to industrial or medical environments were characterized at the physicochemical level in terms of their hydrophobicity and roughness. We showed that SS was moderately hydrophilic and rough, potentially containing crevices, G was hydrophilic and smooth while PS was hydrophobic and smooth. We further showed that P. aeruginosa cells were more likely able to adhere to SS and G rather than PS surfaces under our experimental conditions. The physiological response of P. aeruginosa when adhering to each of these materials was then evaluated by global proteomic analysis. The abundance of 70 proteins was shown to differ between the materials suggesting that their abundance was modified as a function of the material to which bacteria adhered. Our data lead to enabling the identification of abundance patterns that appeared to be specific to a given surface. Taken together, our data showed that P. aeruginosa is capable of sensing and responding to a surface probably via specific programmes to adapt its physiological response accordingly.

Peptide nucleic acids (PNAs): currently potential bactericidal agents

In recent years, the emergence of ESBL-producing and multi-drug resistant bacteria have been increased and designing novel components is necessary for confrontation these bacteria. Peptide nucleic acids (PNAs) are one of the synthetic components that bind to single strand DNA and RNA. Applications of these components are wide while, and one of the important applications of these components is inhibition of gene expression and knock downing the target gene follow as inhibition of bacterial growth. For PNA targeting gene, peptide-PNAs (PPNA) activity cannot be occurred without sequence homology, at the same time, it has been affected by sequence-based specific target and dose-dependent-based manner. Choosing the conserved sequence in different bacterial genus can provide broad-spectrum antimicrobial activity. In this review article, we studied several research papers and extract PNA targeting genes that cause gene knock down and inhibition of bacterial growth. Some novel opportunities for advancement and the design ultra-narrow-spectrum antimicrobial drugs against multi-drug can be accessible by utilizing PNA against necessary genes of pathogens. These results open novel vision for therapeutic intervention. Future researches are required to evaluate the safety, toxicity and pharmacokinetics properties of PPNAs in order to be utilized in clinical treatment.

Flagella but not type IV pili are involved in the initial adhesion of Pseudomonas aeruginosa PAO1 to hydrophobic or superhydrophobic surfaces

Over the last decades, surface biocontamination has become a major concern in food industries and medical environments where its outcomes could vary from financial losses to public health issues. Understanding adhesion mechanisms of involved microorganisms is essential to develop new strategies of prevention and control. Adhesion of Pseudomonas aeruginosa, a nosocomial pathogenic bacterium, relies on several bacterial features, among which are bacterial appendages such as flagella and type IV pili. Here, we examine the role of P. aeruginosa PAO1 flagella and type IV pili in the adhesion to abiotic surfaces with various hydrophobicities. Adhesion kinetics showed, that after 60min, flagella increased the adhesion of the strain to surfaces with high hydrophobicity while no effect was observed on hydrophilic surfaces. Flagella of adherent bacteria exhibited specific and conserved pattern on the surfaces that suggested a higher affinity of flagella for hydrophobic surfaces. Based on these results and on previous studies in the literature, we proposed a model of flagella-mediated adhesion onto hydrophobic surfaces where these appendages induce the first contact and promote the adhesion of the bacterial body. These findings suggest that anti-bioadhesive surface design should take into consideration the presence of bacterial appendages.

Percutaneous endoscopic gastrostomy versus nasogastric feeding in older individuals with non-stroke dysphagia: a systematic review

OBJECTIVE

The objective of this systematic review was to evaluate existing studies on the effectiveness of percutaneous endoscopic gastrostomy (PEG) feeding compared to nasogastric (NG) feeding for patients with non-stroke related dysphagia.

METHODS

We searched Ovid MEDLINE, EMBASE, the Cochrane Library, Web of Science and PubMed databases through to December 2013 using the terms "percutaneous endoscopic gastrostomy", "gastrostomy", "PEG", "nasogastric", "nasogastric tube", "nasogastric feeding" and "intubation". We included randomized controlled trials (RCTs) and non-RCTs which compared PEG with NG feeding in individuals with non-stroke dysphagia.

RESULTS

9 studies involving 847 participants were included in the final analysis, including two randomized trials. Pooled analysis indicated no significant difference in the risk of pneumonia [relative risk (RR) = 1.18, 95% confidence interval (CI) = 0.87-1.60] and overall complications [relative risk (RR) = 0.80, 95% confidence interval (CI) = 0.63-1.02] between PEG and NG feeding. A meta-analysis was not possible for mortality and nutritional outcomes, but three studies suggested improved mortality outcomes with PEG feeding while two out of three studies reported PEG feeding to be better from a nutritional perspective.

CONCLUSIONS

Firm conclusions could not be derived on whether PEG feeding is beneficial over NG feeding in older persons with non-stroke dysphagia, as previously published literature were unclear or had a high risk of bias. A well-designed and adequately powered RCT, which includes carer strain and quality of life as outcome measures is therefore urgently needed.

Microbial biofilms and gastrointestinal diseases

The majority of bacteria live not planktonically, but as residents of sessile biofilm communities. Such populations have been defined as 'matrix-enclosed microbial accretions, which adhere to both biological and nonbiological surfaces'. Bacterial formation of biofilm is implicated in many chronic disease states. Growth in this mode promotes survival by increasing community recalcitrance to clearance by host immune effectors and therapeutic antimicrobials. The human gastrointestinal (GI) tract encompasses a plethora of nutritional and physicochemical environments, many of which are ideal for biofilm formation and survival. However, little is known of the nature, function, and clinical relevance of these communities. This review summarizes current knowledge of the composition and association with health and disease of biofilm communities in the GI tract.

Risk factors for developing clinical infection with carbapenem-resistant Klebsiella pneumoniae in hospital patients initially only colonized with carbapenem-resistant K pneumoniae

BACKGROUND

This study examined predictors of carbapenem-resistant Klebsiella pneumoniae (CRKP) colonization and risk factors for the development of CRKP infection in patients initially only colonized with CRKP.

METHODS

A total of 464 patients with CRKP rectal colonization (CRKP-RC) were identified. Two case-control studies were performed, one comparing risk factors for CRKP-RC in patients who did not develop CRKP infection (CRKP-IN) versus patients without CRKP-RC and CRKP-IN, and the other comparing CRKP-RC patients who did not develop CRKP-IN with those who did.

RESULTS

Forty-two of the 464 colonized patients developed CRKP-IN. Multivariate analysis identified the following predictors for CRKP-RC: antibiotic therapy (odds ratio [OR], 5.76; P ≤ .0001), aminopenicillin therapy (OR, 7.753; P = .004), bedridden (OR, 3.09; P = .021), and nursing home residency (OR, 3.09; P = .013). Risk factors for CRKP-IN in initially CRKP-RC-positive patients were previous invasive procedure (OR, 5.737; P = .021), diabetes mellitus (OR, 4.362; P = .017), solid tumor (OR, 3.422; P = .025), tracheostomy (OR, 4.978; P = .042), urinary catheter insertion (OR, 4.696; P = .037), and antipseudomonal penicillin (OR, 23.09; P ≤ .0001).

CONCLUSIONS

We suggest that in patients with CRKP-RC, a strategy for preventing CRKP-IN might include limiting antipseudomonal penicillin and carbapenem use and preventing infections by closely following compliance with infection control bundles.

Staphylococcus aureus colonization in the nasopharynx of nasogastric tube-fed patients in a long-term care facility

The purpose of this paper is to investigate whether the presence of a nasogastric tube (NGT) for feeding has an impact on the nasal colonization by Staphylococcus aureus. Three groups of frail elderly were examined: 76 patients fed by NGTs and 52 orally fed patients in skilled nursing wards, and 33 orally fed patients in regular nursing wards. Samples from the nasal and oral cavities were cultured for S. aureus and susceptibility testing for oxacillin was performed. The prevalence of S. aureus (either oxacillin-susceptible or oxacillin-resistant) in the NGT-fed group was not significantly different to that in the two orally fed groups nor the nostril in which the NGT was placed. A significant correlation in colonization was found between the two nares and between the nares and oral cavity in the same patient (r > 0.45, P < 0.005) for both oxacillin-susceptible and oxacillin-resistant S. aureus. The presence of NGTs for feeding in elderly frail patients is not associated with higher rates of S. aureus colonization in the nares or oral cavity.

Genetic relationships between respiratory pathogens isolated from dental plaque and bronchoalveolar lavage fluid from patients in the intensive care unit undergoing mechanical ventilation

BACKGROUND

Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in patients hospitalized in intensive care units. Recent studies suggest that dental plaque biofilms serve as a reservoir for respiratory pathogens. The goal of this study was to determine the genetic relationship between strains of respiratory pathogens first isolated from the oral cavity and later isolated from bronchoalveolar lavage fluid from the same patient undergoing mechanical ventilation with suspected VAP.

METHODS

Plaque and tracheal secretion samples were obtained on the day of hospital admission and every other day thereafter until discharge from the intensive care unit from 100 patients who underwent mechanical ventilation. Bronchoalveolar lavage was performed for 30 patients with suspected VAP. Pulse-field gel electrophoresis and multilocus sequence typing were used to determine the genetic relatedness of strains obtained from oral, tracheal, and bronchoalveolar lavage samples.

RESULTS

Isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter species, and enteric species recovered from plaque from most patients were indistinguishable from isolates recovered from bronchoalveolar lavage fluid (i.e., had >95% similarity of pulse-field gel electrophoresis patterns). Nearly one-half of the Pseudomonas strains showed identical genetic profiles between patients, which suggested a common environmental source of infection.

CONCLUSIONS

Respiratory pathogens isolated from the lung are often genetically indistinguishable from strains of the same species isolated from the oral cavity in patients who receive mechanical ventilation who are admitted to the hospital from the community. Thus, dental plaque serves as an important reservoir for respiratory pathogens in patients who undergo mechanical ventilation.

Role of the lysozyme inhibitor Ivy in growth or survival of Escherichia coli and Pseudomonas aeruginosa bacteria in hen egg white and in human saliva and breast milk

Ivy is a lysozyme inhibitor that protects Escherichia coli against lysozyme-mediated cell wall hydrolysis when the outer membrane is permeabilized by mutation or by chemical or physical stress. In the current work, we have investigated whether Ivy is necessary for the survival or growth of E. coli MG1655 and Pseudomonas aeruginosa PAO1 in hen egg white and in human saliva and breast milk, which are naturally rich in lysozyme and in membrane-permeabilizing components. Wild-type E. coli was able to grow in saliva and breast milk but showed partial inactivation in egg white. The knockout of Ivy did not affect growth in breast milk but slightly increased sensitivity to egg white and caused hypersensitivity to saliva, resulting in the complete inactivation of 10(4) CFU ml(-1) of bacteria within less than 5 hours. The depletion of lysozyme from saliva completely restored the ability of the ivy mutant to grow like the parental strain. P. aeruginosa, in contrast, showed growth in all three substrates, which was not affected by the knockout of Ivy production. These results indicate that lysozyme inhibitors like Ivy promote bacterial survival or growth in particular lysozyme-rich secretions and suggest that they may promote the bacterial colonization of specific niches in the animal host.

Health benefits and reductions in bacteria from enhanced oral care

This investigation assessed the oral cavity and microbiological status of 36 non-verbal persons with developmental disabilities. The authors examined oral hygiene interventions aimed at reducing risk factors linked to bacterial colonization and aspiration pneumonia. The findings indicated a statistically significant decrease of potentially pathogenic bacteria and a reduction in total bacteria counts for people receiving oral care via intermittent suction.

Roles for flagellar stators in biofilm formation by Pseudomonas aeruginosa

While Pseudomonas aeruginosa has only a single flagellum, its genome encodes two flagellar stators, called MotAB and MotCD. Here we report that despite no apparent alterations in swimming motility, mutations in either the MotAB or the MotCD stator render the strains defective for biofilm formation in both static and flow cell systems. Our data suggest distinct roles for the stators in early biofilm formation, with both the MotAB and MotCD stators playing a role in initial polar attachment of the bacterial cell to the surface (reversible attachment) and the MotAB stator also participating in the downstream adherence event of irreversible attachment. We also show that the initial polar attachment of P. aeruginosa to two different abiotic surfaces occurs largely at the flagellated end of the cell, a finding that should help develop models for early attachment events. Interestingly, in flowing conditions, a mutation in either stator alone revealed a more severe biofilm defect than mutating both stators or mutating the flagellum. Our data suggest that defects in biofilm formation observed for the stator mutants may be in part due to impacting flagellar reversal rates.

Effect of inhaled budesonide on oropharyngeal, Gram-negative bacilli colonization in asthma patients

BACKGROUND AND OBJECTIVE

The effect of inhaled budesonide on oropharyngeal Gram-negative bacilli colonization (OGNBC) in asthmatic patients was investigated.

METHODS

Oropharyngeal cultures were obtained from asthmatic patients attending the hospital respiratory outpatient clinic, at baseline and 1 month after treatment with 800 microg/day of inhaled budesonide. Cultures were evaluated for OGNBC and compared with those of healthy controls.

RESULTS

A total of 148 cultures (74 from asthma patients, 74 from healthy controls) were evaluated. Six cultures (8.1%) from healthy controls, eight cultures (10.8%) from asthma patients obtained before treatment and 20 cultures (27.0%) obtained after treatment were positive for OGNBC (P < 0.05). Gender, age, presence of atopy and the degree of illness were not found to be related to the presence of OGNBC in and healthy control cultures. In the cultures obtained from the patients after treatment, OGNBC was higher in patients >50 years and in those with FEV1 < 70% (P < 0.05). Nine (18.8%) of 48 patients <50 years compare with 11 (42.3%) of the 26 patients >50 revealed OGNBC (P < 0.05). OGNBC were observed in 18.9% of the patients with FEV1 = 70% and in 47.6% of those with FEV1 < 70% (P < 0.05).

CONCLUSIONS

The increased rate of OGNBC in asthma patients treated with inhaled budesonide was found to be related to increased age and lower level of FEV1. Further studies with larger numbers of patients are required for the interpretation of this colonization in the course of lower respiratory infections in these patients.

Pathogenic Colonization of the Stomach in Enterally Fed Elderly Patients: Comparing Percutaneous Endoscopic Gastrostomy with Nasogastric Tube

OBJECTIVES

To compare the gastric juice microbiota of older people fed through a percutaneous endoscopic gastrostomy tube (PEG) with that of those fed through a nasogastric tube (NGT).

DESIGN

Prospective comparative study.

SETTING

Nursing and skilled nursing wards.

PARTICIPANTS

Fifty-four elderly PEG-fed and 52 NGT-fed patients.

MEASUREMENTS

Cultures from the oropharynx and the gastric juice.

RESULTS

Pathogenic bacteria were isolated from the oropharynxes of 44% of the PEG-fed patients and 54% of the NGT-fed patients. The most frequent gram-negative bacilli isolated from the oropharynx were Proteus spp. (13-21%) and Pseudomonas aeruginosa (13-18%), with no significant difference between the groups. Isolation rates from the gastric juice were significantly more frequent in the NGT-fed patients than in the PEG-fed patients for Proteus spp. (4% vs 23%), Escherichia coli (6% vs 21%), and mixed flora (11% vs 27%). Significant correlation was found between high gastric pH and the isolation of bacteria in both groups (correlation coefficient = 0.58, P < .001).

CONCLUSION

Gastric juice of PEG-fed patients harbors pathogenic bacteria in significant numbers. No significant difference was noted with respect to the rate of isolation of pathogenic bacteria from the oropharynx between the groups. Major bacterial pathogens, such as P. aeruginosa and Proteus spp., were isolated significantly more from the gastric juice of NGT-fed patients. These results support the view that a bidirectional spread pattern of pathogens may take place in NGT-fed patients.

Antibiotic regimens and intestinal colonization with antibiotic-resistant gram-negative bacilli

The intestinal tract provides an important reservoir for antibiotic-resistant gram-negative bacilli, including Enterobacteriaceae species, Pseudomonas aeruginosa, and Acinetobacter baumannii. Selective pressure exerted by antibiotics plays a crucial role in the emergence and dissemination of these pathogens. Many classes of antibiotics may promote intestinal colonization by health care-associated gram-negative bacilli, because the organisms are often multidrug resistant. Antibiotics may inhibit colonization by gram-negative pathogens that remain susceptible, but the benefits of this effect are often limited because of the emergence of resistance. Antibiotic formulary alterations and standard infection control measures have been effective in controlling outbreaks of colonization and infection with antibiotic-resistant gram-negative pathogens. Additional research is needed to clarify the role of strategies such as selective decontamination of the digestive tract and decontamination of environmental surfaces and of patients' skin and wounds.

Microbial flora on operating room telephones

Approximately 500,000 surgical site infections (SSIs) occur each year in the United States. The purpose of this study was to determine if the bacteria most frequently involved in SSIs could be found on telephones in the OR. Twenty-six cultures were taken from telephones in 14 ORs and two substerile rooms at a large teaching medical center. Using standard laboratory procedures, the researchers identified coagulase-negative staphylococci in the cultures. The study found that telephones in the OR can serve as reservoirs for SSI-causing bacteria.

Gastric microbiota in elderly patients fed via nasogastric tubes for prolonged periods

Aspiration of oropharyngeal contents is a constant threat for elderly patients fed via a nasogastric tube (NGT). Colonization of the oropharynx of these patients by pathological flora and the development of biofilms on the feeding tube has been documented recently. In addition, the presence of the NGT may interfere with the gastro-oesophageal sphincter, leading to gastro-oesophageal reflux. Thus, the passage of pathogenic bacteria in both directions is facilitated. The purpose of this study was to explore the microbiota of the gastric juice and the oropharynx in NGT-fed elderly patients. Samples of gastric juice were drawn after an overnight fast, and microbial cultures and direct pH measurement were performed. Concomitant cultures were obtained from the oropharynx. Overall, 107 gastric and oropharyngeal cultures were obtained from 52 subjects. Pathogenic flora (Gram-negative bacteria or Staphylococcus aureus) were isolated from 74% of stomach samples and from 69% of oropharynx samples. Proteus spp. (26%) and Escherichia coli (22%) were the most common isolates in the gastric juice, and Proteus spp. (24%) and Pseudomonas spp. (21%) were the most common isolates in the oropharynx. Similarity in the composition of the oropharynx and gastric flora was observed in most cases. The gastric pH was relatively high (4.57 +/- 0.65 at 3 h after feeding and 4.2 +/- 0.9 at 12 h after feeding) and was highly correlated with the isolation of pathogenic bacteria (r = 0.58, P < 0.01). These results support the view that in addition to the oropharynx, the stomach of NGT-fed elderly patients constitutes a reservoir of pathogens that could be associated with the risk of aspiration pneumonia. The cause of the high gastric pH and its relation to pathogenic bacteria warrants further study.

Cross-transmission of nosocomial pathogens in an adult intensive care unit: incidence and risk factors

The incidence and determinants of cross-transmission in an adult intensive care unit (ICU) were examined under normal conditions. Four hundred and thirty patients were followed for 3947 patient-days. Cross-transmitted pathogens were identified by genetic typing. A cross-transmission episode was defined as when two or more patients had indistinguishable isolates and had been treated in the ICU during intervals up to seven days apart. The direction of cross-transmission was confirmed if the incriminated pathogen was isolated from the donor before admission of the recipient; otherwise, both patients could potentially be a donor or a recipient. These patients were excluded from the risk factor analysis. Recipients of pathogens were compared with those who were not involved in cross-transmission. Out of 22 056 examined specimens, 275 isolates were typed and 40 episodes of cross-transmission were detected. The overall incidence of cross-transmission was 10.7 [95% confidence intervals (CI) 7.6-14.5] per 1000 patient-days. In multivariate analysis, those who were nursed in an understaffed environment [odds ratio (OR) = 3.3, 95% CI 1.4-7.8], had a nasogastric tube (OR = 2.9, 95% CI 1.1-7.8) and were ventilated (OR = 2.5, 95% CI 1.1-6.0) for all of their stay, compared with none or part of their stay, showed an increase in the risk of cross-transmission. Repeated bronchoscopy (OR = 5.1, 95% CI 1.04-25) compared with no bronchoscopy and immunosuppresion (OR = 3.9, 95% CI 1.2-12.5) also increased the risk. This study showed that cross-transmission of nosocomial pathogens in the ICU is associated with understaffing, immunosuppression and factors that result in multiple staff/patient contacts, thus emphasizing the importance of hand hygiene.

Growing and analyzing biofilms in fermenters

One of the most daunting challenges of biofilm research is comparing experimental results produced by multiple laboratories, each of which uses different techniques to generate, analyze, and interpret biofilm data. The heterogeneity inherent to biofilm communities contributes to the difficulty in obtaining reproducible results between experiments within a single laboratory, but the problem is compounded further by a lack of standardization in techniques. A number of biofilm culture methods are presented in this unit to provide a set of standards for biofilm study. Each model system differs in growth conditions, applied variables, and experimental output, all of which must be carefully considered when designing an experiment and, most critically, during data interpretation. In this unit, two methods of biofilm culture that are known to reliably provide reproducible, statistically clean results in determining the viability and antimicrobial susceptibility of biofilm communities are described. The spinning disc model provides multiple biofilm samples from the same biofilm reactor, significantly reducing data variability. The tube biofilm method, in addition to providing this benefit, can be used for expression analysis, and thus can yield informative data on both macro- and micro-scales. These methods also utilize continuous culture, or chemostat, conditions to maintain a quasi-steady state.

Effect of various antibacterial preparations on the pathogenic oral flora in elderly patients fed via nasogastric tube

Oropharyngeal colonization by pathogenic gram-negative bacilli (GNB) and Staphylococcus aureus is associated with aspiration pneumonia. Decolonization in high-risk populations may be important. We prospectively evaluated six antiseptic compounds in nasogastric tube-fed frail elderly patients; only polymixine reduced oropharyngeal colonization with GNB. None had an effect on S. aureus colonization.

Effect of gingival and dental plaque antiseptic decontamination on nosocomial infections acquired in the intensive care unit: a double-blind placebo-controlled multicenter study

OBJECTIVE

To document the effect of gingival and dental plaque antiseptic decontamination on the rate of nosocomial bacteremias and respiratory infections acquired in the intensive care unit (ICU).

DESIGN

Prospective, multicenter, double-blind, placebo-controlled efficacy study.

SETTING

Six ICUs: three in university hospitals and three in general hospitals.

PATIENTS

A total of 228 nonedentulous patients requiring endotracheal intubation and mechanical ventilation, with an anticipated length of stay > or =5 days.

INTERVENTIONS

Antiseptic decontamination of gingival and dental plaque with a 0.2% chlorhexidine gel or a placebo gel, three times a day, during the entire ICU stay.

MEASUREMENTS AND MAIN RESULTS

Demographic and clinical characteristics, organ function data (Logistic Organ Dysfunction score), severity of condition (Simplified Acute Physiologic Score), and dental plaque status were assessed at baseline and until 28 days. Bacteriologic sampling of dental plaque and saliva was done every 5 days, and blood, tracheal aspirate, and bronchoalveolar lavage cultures were performed when appropriate. The primary efficacy end point was the incidence of bacteremia, bronchitis, and ventilator-associated pneumonia, expressed as a percentage and per 1000 ICU days. All baseline characteristics were similar between the treated and the placebo groups. The incidence of nosocomial infections was 17.5% (13.2 per 1000 ICU days) in the placebo group and 18.4% (13.3 per 1000 ICU days) in the plaque antiseptic decontamination group (not significant). No difference was observed in the incidence of ventilator-associated pneumonia per ventilator or intubation days, mortality, length of stay, and care loads (secondary end points). On day 10, the number of positive dental plaque cultures was significantly lower in the treated group (29% vs. 66%; p < .05). Highly resistant Pseudomonas, Acinetobacter, and Enterobacter species identified in late-onset ventilator-associated pneumonia and previously cultured from dental plaque were not eradicated by the antiseptic decontamination. No side effect was reported.

CONCLUSIONS

Gingival and dental plaque antiseptic decontamination significantly decreased the oropharyngeal colonization by aerobic pathogens in ventilated patients. However, its efficacy was insufficient to reduce the incidence of respiratory infections due to multiresistant bacteria.

Pneumonia in the elderly (geriatric) population

PURPOSE OF REVIEW

Review of recent studies (2003 and 2004) concerning pneumonia in the very old.

RECENT FINDINGS

Hospitalisation for community-acquired pneumonia (CAP) in the elderly is associated with a high mortality and with a high rate of readmission within the following year. Functional status, altered mental status, number of comorbidities, aspiration pneumonia, renal failure, and nutritional status are all indicators of adverse prognosis. Although Streptococcus pneumoniae, Haemophilus influenzae, Enterobacteriacae, and Staphylococcus aureus are the most frequently identified causative microorganisms, viruses account for up to 26% of hospital admissions for CAP. Chlamydia pneumoniae is also implicated in CAP and in nursing-home-acquired pneumonia (NHAP), with recent reports of outbreaks in nursing homes. Aspiration pneumonia is frequent in the elderly and occurs with increased frequency in patients with nasogastric tubes or percutaneous enterogastric tubes. In severe aspiration pneumonia, 20% of organisms implicated are anaerobic and 80% aerobic, most of which are gram-negative Enterobacteriaceae. Poor oral hygiene increases subsequent risk of pneumonia: dental plaque may act as a reservoir for pathogenic organisms implicated in CAP or NHAP. Prevention of CAP and NHAP relies on the combined use of influenza and pneumococcal vaccination, which decreases hospital admissions and in-hospital mortality for CAP.

SUMMARY

Recent studies stress the importance of aspiration as a frequent mechanism of CAP, provide new insights as to causative organisms in this setting, and underline the contribution of combined vaccination in reducing morbidity and mortality.

Colonization and resistance dynamics of gram-negative bacteria in patients during and after hospitalization

The colonization and resistance dynamics of aerobic gram-negative bacteria in the intestinal and oropharyngeal microfloras of patients admitted to intensive care units (ICU) and general wards were investigated during and after hospitalization. A total of 3,316 specimens were obtained from patients upon admission, once weekly during hospitalization, at discharge from the ICU, at discharge from the hospital, and 1 and 3 months after discharge from the hospital. Five colonies per specimen were selected for identification and susceptibility testing. In both patient populations, the gram-negative colonization rates in oropharyngeal specimens increased during hospitalization and did not decrease in the 3 months after discharge. In rectal specimens, colonization rates decreased during hospitalization and increased after discharge. There was a change in species distribution among the dominant microfloras during hospitalization. Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa were isolated more often, whereas the frequency of Escherichia coli declined. The percentage of ICU patients colonized with ampicillin- and/or cephalothin-resistant fecal E. coli was significantly increased at discharge from the hospital and did not change in the 3 months after discharge. The emergence of multidrug resistance was observed for E. coli during patient stays in the ICU. Resistance frequencies in E. coli significantly increased with the length of stay in the ICU. For the general ward population, no significant changes in resistance frequencies were found during hospitalization. From a population perspective, the risk of dissemination of resistant gram-negative bacteria into the community through hospitalized patients appears to be low for general ward patients but is noticeably higher among ICU patients.

[Enteral feeding by nasogastric tube in mandibular fracture osteosynthesis]

INTRODUCTION

Mandibular fractures are among the most common fractures of the face; their treatment consists in a reduction by intermaxillary blocking then miniplate osteosynthesis. In our unit we systematically insert a nasogastric tube for enteral feeding to improve nutrition and to protect healing. Since the beginning of 2002, a series of patients operated for simple mandibular fractures were fed immediately after the operation by a semiliquid food. The purpose of this work is to verify the real advantage of enteral feeding by nasogastric tube in patients operated for simple fractures of the mandible.

MATERIAL AND METHOD

This retrospective study includes all the patients operated for closed fractures of the toothed portion of the mandible from January 1999 to October 2003. There were two series, a first series of patients operated between 1999 and 2002 fed by nasogastric tube until mouth healing and the second series of patients operated between 2002 and 2003 fed by mixed oral-enteral nutrition from the first postoperative day. We analyzed demographic features, time between trauma and operation, type of fracture, feeding modalities, duration of use of the nasogastric tube, duration of hospital stay and postoperative complications.

RESULTS

A total of 111 patients were included in the study. The first group of 81 patients fed by nasogastric tubes included 19 women and 62 men with an average age of 29.7 years (from 15 to 81 years). The average time from trauma to operation was 2.3 days (0 to 5 days), the feeding by nasogastric tubes was maintained 5.9 days after the operation (4 to 12 days), the average hospital stay was 7.2 days (5 to 13 days). Eleven immediate complications were observed (13.6%). The second group of 30 patients fed orally the day after the intervention included 7 women and 23 men. The average time from trauma to operation was 2.2 days (0 to 7 days), the average hospital stay was 2.5 days (2 to 3 days). One complication was observed (3.3%).

DISCUSSION

Immediate oral feeding the day after the operation for simple closed mandibular fractures provides certain comfort for the patient by avoiding the inconveniences of nasogastric feeding tubes without increasing the rate of postoperative complications such as disunion, delayed healing or infection. The hospital stay is significant shortened, enabling a real cost savings.

Pathogen-host interactions in Pseudomonas aeruginosa pneumonia

Pseudomonas aeruginosa is an important pathogen causing a wide range of acute and chronic infections. P. aeruginosa rarely causes infection in the normal host, but is an efficient opportunistic pathogen causing serious infections in patients who are mechanically ventilated, individuals who are immunocompromised, and patients with malignancies or HIV infection. Among these risk groups, the most vulnerable hosts are neutropenic and patients who are mechanically ventilated. In addition, P. aeruginosa is the most prevalent chronic infection contributing to the pathogenesis of cystic fibrosis. Because of the ubiquitous nature of P. aeruginosa and its ability to develop resistance to antibiotics, it continues to be problematic from a treatment perspective. The pathogenicity of P. aeruginosa is largely caused by multiple bacterial virulence factors and genetic flexibility enabling it to survive in varied environments. Lung injury associated with P. aeruginosa infection results from both the direct destructive effects of the organism on the lung parenchyma and exuberant host immune responses. This article focuses on the major bacterial virulence factors and important aspects of the host immunity that are involved in the pathogenesis of serious P. aeruginosa infection. In addition to antibiotic therapy, strategies directed toward enhancing host defense and/or limiting excessive inflammation could be important to improve outcome in P. aeruginosa lung infections.

Cycling empirical antimicrobial agents to prevent emergence of antimicrobial-resistant Gram-negative bacteria among intensive care unit patients

OBJECTIVE

To determine the impact of the rotation of antimicrobial agents on the rates of infection, intestinal colonization, and acquisition with antimicrobial-resistant Gram-negative bacteria.

DESIGN

Pre- and postintervention design.

SETTING

A 19-bed, medical intensive care unit.

PATIENTS

Individuals admitted to the study unit for >48 hrs.

INTERVENTIONS

After a 5-month baseline observation period, four classes of antimicrobial agents with Gram-negative activity were cycled at 3- to 4-month intervals for 24 months.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the acquisition rate of antimicrobial resistance among Enterobacteriaceae and Pseudomonas aeruginosa obtained from rectal swab cultures performed on admission, weekly during the patients' stay, and at discharge. Rates and microbiology of nosocomial bloodstream infections and ventilator-associated pneumonia were also compared between baseline and cycling periods. The cycling program resulted in a significant change in prescribing practices; the predominant agent used changed with each cycle. Among study patients who were not already colonized with a resistant organism, the rate of acquisition of enteric colonization with bacteria resistant to any of the target drugs remained stable during the cycling period for P. aeruginosa (relative rate, 0.96; 95% confidence Interval, 0.47-2.16) and Enterobacteriaceae (relative rate, 1.57; 95% confidence interval, 0.80-3.43). Hospital-wide, P. aeruginosa from routine clinical cultures resistant to the target drugs increased during the cycling period. The proportion of Gram-negative bacteria isolated from cases of nosocomial bloodstream infection (29% baseline vs. 26% cycling; p = .11) and ventilator-associated pneumonia (80% vs. 41%; p = .06) did not significantly differ.

CONCLUSIONS

In this study, antimicrobial cycling did not result in a significant change in enteric acquisition of resistant Gram-negative bacteria among intensive care unit patients.

Biochemical, immunological and enzymatic components of saliva in prolonged naso-gastric-fed elderly patients

BACKGROUND AND AIMS

We have previously shown that naso-gastric tube (NGT)-fed patients harbor pathogenic flora in their oropharynx. The purpose of this study was to examine comparatively the biochemical, immunological and enzymatic components of the saliva of these patients with that of orally-fed counterparts.

METHODS

The study group consisted of 19 elderly NGT-fed patients and 18 comparable patients on oral feeding. Unstimulated whole saliva was collected and analyzed according to accepted methods for sodium, potassium, chloride, uric acid, total protein, albumin, amylase, lysozyme, and immunoglobulins, IgM, IgG, IgA, as well as secretory IgA.

RESULTS

None of the above tested salivary components significantly differed between the two groups. Only uric acid levels were significantly lower (50%, p < 0.05) in NGT-fed patients.

CONCLUSIONS

Uric acid is the main antioxidant component of saliva and, as such, it may be related to pathogenic bacterial colonization of the oropharynx in NGT-fed patients, with the risk of aspiration pneumonia.

The Role of the Intestinal Tract As a Source for Transmission of Nosocomial Pathogens

The intestinal tract provides an important source for transmission of many nosocomial pathogens, including Enterococcus species, Clostridium difficile, Candida species, Enterobacteriaceae, and other gram-negative bacilli. Recent data suggest that the intestinal tracts of hospitalized patients may also be an important reservoir of Staphylococcus aureus. Although the clinical manifestations of these pathogens are diverse, a common pathogenesis is involved in their colonization of and dissemination from the intestinal tract. Of particular importance is the role that antibiotic selective pressure plays in promotion of colonization by antibiotic-resistant pathogens. Strategies to limit the spread of these pathogens must include efforts to improve adherence to standard infection control practices and promotion of good antimicrobial stewardship. New strategies that include application of novel technologies to the problem of pathogen transmission are needed, and additional research is needed to clarify the potential utility of selective decontamination of the digestive tract.

The Role of the Intestinal Tract as a Reservoir and Source for Transmission of Nosocomial Pathogens

The intestinal tract provides an important reservoir for many nosocomial pathogens, including Enterococcus species, Enterobacteriaciae, Clostridium difficile, and Candida species. These organisms share several common risk factors and often coexist in the intestinal tract. Disruption of normal barriers, such as gastric acidity and the indigenous microflora of the colon, facilitates overgrowth of pathogens. Factors such as fecal incontinence and diarrhea contribute to the subsequent dissemination of pathogens into the health care environment. Selective pressure exerted by antibiotics plays a particularly important role in pathogen colonization, and adverse effects associated with these agents often persist beyond the period of treatment. Infection-control measures that are implemented to control individual pathogens may have a positive or negative impact on efforts to control other pathogens that colonize the intestinal tract.