Bacteriology of lower-respiratory-tract secretions, sputum, and upper-respiratory-tract secretions in "normals" and chronic bronchitics

Improved Detection of Respiratory Pathogens by Use of High-Quality Sputum with TaqMan Array Card Technology

New diagnostic platforms often use nasopharyngeal or oropharyngeal (NP/OP) swabs for pathogen detection for patients hospitalized with community-acquired pneumonia (CAP). We applied multipathogen testing to high-quality sputum specimens to determine if more pathogens can be identified relative to NP/OP swabs. Children (<18 years old) and adults hospitalized with CAP were enrolled over 2.5 years through the Etiology of Pneumonia in the Community (EPIC) study. NP/OP specimens with matching high-quality sputum (defined as ≤10 epithelial cells/low-power field [lpf] and ≥25 white blood cells/lpf or a quality score [q-score] definition of 2+) were tested by TaqMan array card (TAC), a multipathogen real-time PCR detection platform. Among 236 patients with matched specimens, a higher proportion of sputum specimens had ≥1 pathogen detected compared with NP/OP specimens in children (93% versus 68%; P < 0.0001) and adults (88% versus 61%; P < 0.0001); for each pathogen targeted, crossing threshold (CT) values were earlier in sputum. Both bacterial (361 versus 294) and viral detections (245 versus 140) were more common in sputum versus NP/OP specimens, respectively, in both children and adults. When available, high-quality sputum may be useful for testing in hospitalized CAP patients.

Ventilator-Associated Pneumonia: A Review

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose on the health care system. The causes of ventilator-associated pneumonia are varied and differ across different patient populations and different types of ICUs. This varied presentation underscores the need for the intensivist treating the patient with ventilator-associated pneumonia to have a clear knowledge of the ambient microbiologic flora in their ICU. Prevention of this disease process is of paramount importance and requires a multifaceted approach. Once a diagnosis of ventilator-associated pneumonia is suspected, early broad-spectrum antibiotic administration decreases morbidity and mortality and should be based on knowledge of the sensitivities of common infecting organisms in the ICU. De-escalation of therapy, once final culture results are available, is necessary to minimize development of resistant pathogens. Duration of therapy should be based on the patient’s clinical response, and every effort should be made to minimize duration of therapy, thus further minimizing the risk of resistance.

Community dynamics and the lower airway microbiota in stable chronic obstructive pulmonary disease, smokers and healthy non-smokers

RATIONALE

The role bacteria play in the progression of COPD has increasingly been highlighted in recent years. However, the microbial community complexity in the lower airways of patients with COPD is poorly characterised.

OBJECTIVES

To compare the lower airway microbiota in patients with COPD, smokers and non-smokers.

METHODS

Bronchial wash samples from adults with COPD (n=18), smokers with no airways disease (n=8) and healthy individuals (n=11) were analysed by extended-culture and culture-independent Illumina MiSeq sequencing. We determined aerobic and anaerobic microbiota load and evaluated differences in bacteria associated with the three cohorts. Culture-independent analysis was used to determine differences in microbiota between comparison groups including taxonomic richness, diversity, relative abundance, 'core' microbiota and co-occurrence.

MEASUREMENT AND MAIN RESULTS

Extended-culture showed no difference in total load of aerobic and anaerobic bacteria between the three cohorts. Culture-independent analysis revealed that the prevalence of members of Pseudomonas spp. was greater in the lower airways of patients with COPD; however, the majority of the sequence reads for this taxa were attributed to three patients. Furthermore, members of Bacteroidetes, such as Prevotella spp., were observed to be greater in the 'healthy' comparison groups. Community diversity (α and β) was significantly less in COPD compared with healthy groups. Co-occurrence of bacterial taxa and the observation of a putative 'core' community within the lower airways were also observed.

CONCLUSIONS

Microbial community composition in the lower airways of patients with COPD is significantly different to that found in smokers and non-smokers, indicating that a component of the disease is associated with changes in microbiological status.

The influence of stents on microbial colonization of the airway in children after slide tracheoplasty: a 14-year single-center experience

OBJECTIVES

This study describes the microbial colonization profile of the airway in children after slide tracheoplasty (STP) with and without stents, and compares colonization to children undergoing cardiothoracic surgical procedures without airway related disease.

METHODS

A 14-year retrospective single case note review was performed on patients undergoing STP and stent insertion. Nose and throat (NT) and bronchoalveolar lavage (BAL) specimens were analyzed for microbial profile and expressed as cumulative mean microorganisms per patient (MMP).

RESULTS

Forty-three patients (median age ± SD 15.02 ± 31.76 months) underwent STP and 141 patients underwent cardiothoracic but no airway surgery (median age ± SD 31.7 ± 47.2 months). Sixteen patients required a stent after STP. One-hundred seventy-two positive microbial specimens were identified. The predominant 6 microorganisms were (1) Staphylococcus aureus; (2) Pseudomonas aeruginosa; (3) Haemophilus influenzae not type B; (4) Coliforms; (5) Streptococcus pneumoniae; and (6) Candida Albicans, and accounted for 128 (74%) of all positive specimens found. Children with stents had more MMP compared to children without stents after STP [4.06 ± 2.38 and 2.04 ± 2.24 MMP (P < 0.001), respectively]. Both groups of children after STP had more MMP compared to the control group (P < 0.001). Children with stents had more microbial colonization of their lower respiratory tract compared to their upper respiratory tract (3.36 ± 2.02 and 1.36 ± 0.93 MMP (P < 0.01) respectively). Staphylococcus aureus colonization of the lower respiratory tract was significantly higher in children with stents compared to children without stents after STP [0.5 and 0.15 MMP (P < 0.05) respectively].

CONCLUSIONS

This study indicates airway surgery and the subsequent use of stents to be a significant risk factor for microbial colonization of the airway in children. More specifically airway stents appear to increase colonization in the distal airway, which appears unrelated to that of the upper respiratory tract.

Macrolide immunomodulatory effects and symptom resolution in acute exacerbation of chronic bronchitis and acute maxillary sinusitis: a focus on clarithromycin

Bacterial respiratory tract infections are common in the primary care setting and patients often seek the assistance of a healthcare professional in order to achieve resolution of their symptoms. Antibiotic agents that offer rapid symptom relief, in addition to excellent bacteriological and clinical cure, are highly desired. Macrolides have proven to be highly effective in treating acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis. In addition, immunomodulatory effects that may contribute to symptom resolution have been reported. This article reviews current literature on symptom resolution in acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis, with a focus on clarithromycin, and explores the potential mechanisms that may contribute to this action.

Pathology of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease is one of the leading causes of death and morbidity worldwide. Despite intensive investigation, its pathology and pathophysiology are not well understood. The hallmarks of the disease are irreversible airflow limitation and chronic inflammation. Small airway obstruction due to progressive inflammation and fibrosis, and the loss of elastic recoil mediated by elastolysis and apoptosis equally contribute to pathologic changes. However, it is debated to what extent the obstruction of large airways leads to altered lung function. Three morphologic entities are described in the literature under one disease; chronic bronchitis, obstructive bronchiolitis and emphysema may appear in the same patient at the same time. The authors review pathologic changes observed in chronic obstructive pulmonary disease, including acute exacerbations and secondary pulmonary hypertension as severe but common complications of the disease. Furthermore, we detail recent scientific evidences for major cellular and molecular inflammatory pathway activation. These mechanisms result in accelerated apoptosis, remodeling and increased proinflammatory cytokine release. Targeting intracellular pathological changes may lead to the discovery of a new generation of drugs that could reduce chronic obstruction before airway irreversibility is established.

Antibiotics in the treatment of acute exacerbations of chronic bronchitis

The benefit of antimicrobial therapy for patients with an acute exacerbation of chronic bronchitis (AECB) remains controversial for two main reasons. First, the distal airways of patients with chronic bronchitis are persistently colonised, even during clinically stable periods, with the same bacteria that have been associated with AECB. Second, bacterial infection is only one of several causes of AECB. These factors have led to conflicting analyses on the role of bacterial agents and the response to antimicrobial therapy of patients with AECB. An episode of AECB is said to be present when a patient with chronic obstructive pulmonary disease (COPD) experiences some combination of increased dyspnoea, increased sputum volume, increased sputum purulence and worsening lung function. While the average COPD patient experiences 2 - 4 episodes of AECB per year, some patients, particularly those with more severe airway obstruction, are more susceptible to these attacks than others. Bacterial agents appear to be particularly associated with AECB in patients with low lung function and those with frequent episodes accompanied by purulent sputum. Non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis account for up to 50% of episodes of AECB. Gram-negative bacilli are more likely to occur in patients with more severe lung disease. Antibiotics have been used to ameliorate AECB, to prevent AECB and to prevent the long-term loss of lung function that characterises COPD. Numerous prevention trials have been conducted with fairly consistent results; antibiotics do not lessen the number of episodes of AECB but do reduce the number of days lost from work. Most antibiotic trials have studied the impact of treatment on episodes of AECB and results have been inconsistent, largely due to patient selection and end point definition. In patients with severe airway obstruction, especially in the presence of purulent sputum, antibiotic therapy significantly shortens the duration of symptoms and can be cost-effective. Over the past 50 years, virtually all classes of antimicrobial agents have been studied in AECB. Important considerations include penetration into respiratory secretions, spectrum of activity and antimicrobial resistance. These factors limit the usefulness of drugs such as amoxicillin, erythromycin and trimethoprim-sulfamethoxazole. Extended-spectrum oral cephalosporins, newer macrolides and doxycycline have demonstrated efficacy in clinical trials. Amoxicillin-clavulanate and flouoroquinolones should generally be reserved for patients with more severe disease. A number of investigational agents, including ketolides and newer quinolones, hold promise for treatment of AECB.

Haemophilus influenzae in acute exacerbations of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common progressive respiratory disease that is associated with infective exacerbations that lead to worsening of symptoms. Many organisms are thought to trigger infective exacerbations, but Haemophilus influenzae is the most commonly isolated bacterium. The role of H. influenzae in infective exacerbations remains uncertain, mainly because the organism chronically colonises patients whose clinical condition is stable. H. influenzae may also comprise part of the normal nasopharyngeal flora in man, making the interpretation of positive cultures difficult in some cases.

Bacterial colonisation in patients with bronchiectasis: microbiological pattern and risk factors

BACKGROUND

A study was undertaken to investigate the incidence, diagnostic yield of non-invasive and bronchoscopic techniques, and risk factors of airway colonisation in patients with bronchiectasis in a stable clinical situation.

METHODS

A 2 year prospective study of 77 patients with bronchiectasis in a stable clinical condition was performed in an 800 bed tertiary university hospital. The interventions used were pharyngeal swabs, sputum cultures and quantitative protected specimen brush (PSB) bacterial cultures (cut off point > or =10(2) cfu/ml) and bronchoalveolar lavage (BAL) (cut off point > or =10(3) cfu/ml).

RESULTS

The incidence of bronchial colonisation with potential pathogenic microorganisms (PPMs) was 64%. The most frequent PPMs isolated were Haemophilus influenzae (55%) and Pseudomonas spp (26%). Resistance to antibiotics was found in 30% of the isolated pathogens. When the sample was appropriate, the operative characteristics of the sputum cultures were similar to those obtained with the PSB taken as a gold standard. Risk factors associated with bronchial colonisation by PPMs in the multivariate analysis were: (1) diagnosis of bronchiectasis before the age of 14 years (odds ratio (OR)=3.92, 95% CI 1.29 to 11.95), (2) forced expiratory volume in 1 second (FEV1) <80% predicted (OR=3.91, 95% CI 1.30 to 11.78), and (3) presence of varicose or cystic bronchiectasis (OR=4.80, 95% CI 1.11 to 21.46).

CONCLUSIONS

Clinically stable patients with bronchiectasis have a high prevalence of bronchial colonisation by PPMs. Sputum culture is a good alternative to bronchoscopic procedures for evaluation of this colonisation. Early diagnosis of bronchiectasis, presence of varicose-cystic bronchiectasis, and FEV1 <80% predicted appear to be risk factors for bronchial colonisation with PPMs.

Nontypeable Haemophilus influenzae in the lower respiratory tract of patients with chronic bronchitis

The frequency of colonization and intracellular localization of nontypeable Haemophilus influenzae (NTHi) in the lower respiratory tract was determined in healthy adults and in clinically stable and acutely ill chronic bronchitis (CB) patients. NTHi was recovered from bronchial wash or bronchial brush specimens in 6 of 23 (26%) stable CB patients and in 1 of 15 (7%) CB patients with a respiratory exacerbation. No NTHi (0 of 26) was recovered from lower tract specimens of healthy adults undergoing anesthesia for elective surgery. Molecular typing of NTHi strains revealed that five of nine patients with stable CB had different strains in upper respiratory tract and bronchial wash/brush specimens collected simultaneously. Four stable patients with CB had different strains recovered on repeat bronchoscopy. These results demonstrate the frequent colonization of the lower airways of stable CB patients with multiple strains of NTHi. Bronchial biopsies also were examined for intracellular NTHi by in situ hybridization and immunofluorescence microscopy. Intracellular NTHi were found in 0 of 7 healthy adults, 8 of 24 patients with clinically stable CB, and 13 of 15 acutely ill CB patients. This observation suggests a role for intracellular infection by NTHi in the pathogenesis of exacerbations of CB.

Bacterial colonization of central airways after stenting

Airway stenting (AS) is increasingly used in the management of obstructive lesions of the central airways. Although retention of secretions and infection have been reported as complications of AS, the microbiological consequences of AS have not yet been evaluated. In this study, we prospectively performed protected specimen brush (PSB) sampling of the airways, before and 3 to 4 wk after AS, in 14 consecutive patients (65 +/- 17 yr), suffering from bronchial (5), extensive esophageal (2), thyroid (1), and adenocystic (1) carcinoma, stenotic tracheal burn lesions (2), postintubation stenosis (2), and Wegener's granulomatosis (1). A cutoff value of >/= 10(2) colony-forming units (cfu). ml(-)(1) was considered diagnostic for airway colonization (AC). PSB results were related to the presence and degree of secretion retention (SR) at the level of the stent. In five of the 14 patients, AC was present prior to AS; in three of these, potentially pathogenic microorganisms (PPM) were identified. After AS, AC was found in 11 (including seven patients without prior AC) of the 14 patients. In six of these patients, one or more PPM were present (Pseudomonas aeruginosa [4], Staphylococcus aureus [3], Streptococcus pneumoniae [1], Klebsiella spp. [1]). Although AC tended to be associated with the presence of SR (PSB >/= 10(2) cfu. ml(-)(1) in 10 of 12 SR-positive and in zero SR-negative cases; PSB < 10(2) cfu. ml(-)(1) in two SR-positive and in two SR-negative cases), statistical significance was not reached (Fisher exact test, p = 0.06). We conclude that AS is frequently followed by AC, the majority of which occurs in patients without AC prior to AS, and is caused by PPM. In no case, however, AC was associated with clinical signs of infection. AC tended to be associated with SR in the stent.

Oropharyngeal gram-negative bacillary carriage in chronic obstructive pulmonary disease: relation to severity of disease

The prolonged presence of aerobic Gram-negative bacilli (AGNB) in the oropharynx is termed 'carriage'. AGNB carriage rates are low in populations of healthy individuals. Previously, severity of underlying disease has been positively correlated with oropharyngeal AGNB carriage rate. Overgrowth of AGNB at the oropharynx poses a significant risk of endogenous infection in end-stage chronic obstructive pulmonary disease (COPD) patients. The aims of this study were to undertake an epidemiological survey of the oropharyngeal flora of COPD patients and to correlate oropharyngeal carriage of AGNB with severity of disease. Two oral rinses were obtained, within a 2-day interval, from 40 COPD patients comprising three disease severity groups: 1. mild, 2. moderate and 3. severe. Eighty oral rinses were quantitatively (1:10 dilution series) cultured for AGNB and yeasts using broth enrichment. The mean AGNB carriage rate was 15%. AGNB carriage rates of 0, 7.7 and 29.4% were observed within the mild, moderate and severe disease groups, respectively. The mean yeast carriage rate was 33.3%. Yeast carriage rates of 33.3, 15.4 and 64.7% were observed within the mild, moderate and severe disease groups, respectively. Carriage of Staphylococcus aureus was 5%. Rates of oropharyngeal carriage of AGNB (1/23 vs. 5/17) and yeasts (5/23 vs. 11/17) were significantly higher within the severe disease group than in non-severe disease groups. Oropharyngeal carriage of AGNB in end-stage COPD patients (forced expiratory volume in 1 sec, FEV1 < 50% predicted) presents a potential source of Gram-negative endogenous pneumonia. This outcome may be promoted by intubation and some flora-suppressing antibiotic therapies.

Oropharyngeal Gram-negative bacillary carriage: a survey of 120 healthy individuals

BACKGROUND

The presence of aerobic Gram-negative bacilli (AGNB) in the oropharynx can be either temporary or persistent. Prolonged colonization (ie, carriage) is distinguished from transient presence (ie, acquisition), which often occurs in healthy individuals but less frequently in those with underlying disease. Prevalence rates of up to 61.1% quoted previously for healthy individuals were obtained by using single sample surveys, which fail to differentiate acquisition from carriage.

STUDY OBJECTIVES

To illustrate the need to distinguish carriage from acquisition in a healthy population at risk of acquisition of AGNB, and to show that although differing groups of healthy individuals may acquire oropharyngeal AGNB at differing frequencies, carriage is rare in healthy individuals.

PARTICIPANTS

Two oral rinses were obtained within a 2-day interval from 120 healthy individuals comprising 40 nurses, 40 students, and 40 laboratory-associated persons.

DESIGN

Two hundred forty oral rinses were quantitatively (1:10 dilution series) cultured for AGNB by using broth enrichment.

MEASUREMENTS AND RESULTS

The rate of AGNB carriage based on two consecutive samples positive for the same AGNB was 6.6%; the rate of AGNB acquisition based on one positive sample was 35.8%. The concentrations of all carried and acquired AGNB were < or = 103 cfu/mL. AGNB acquisition was significantly higher in students (52.5%) compared to nurses (32.5%) and laboratory-associated persons (22.5%; p < 0.05).

CONCLUSION

Healthy individuals rarely carry oropharyngeal AGNB, suggesting effective oropharyngeal clearance in a healthy population predisposed to acquisition. Apparently, the oropharyngeal mucosa in healthy individuals is not receptive to adhesins of AGNB, resulting in rapid elimination of these bacteria.

The role of infection in COPD

Clinical studies of acute exacerbations of COPD are difficult because of the heterogeneous nature of COPD, diffuse symptoms that can vary spontaneously, and difficulties in defining clinical response both in the short and long term. The role of bacterial infection, and thus use of antibiotics, in COPD is controversial. The available evidence shows that bacterial infection has a significant role in acute exacerbations, but its role in disease progression is less certain. Upper respiratory tract commensals, such as nontypable Haemophilus influenzae, cause most bronchial infections by exploiting deficiencies in the host defenses. Some COPD patients are chronically colonized by bacteria between exacerbations, which represents an equilibrium in which the numbers of bacteria are contained by the host defenses but not eliminated. When an exacerbation occurs, this equilibrium is upset and bacterial numbers increase, which incites an inflammatory response. Neutrophil products can further impair the mucosal defenses, favoring the bacteria, but if the infection is overcome, symptoms resolve. However, if the infection persists, chronic inflammation may cause lung damage. About half of exacerbations involve bacterial infection, but these patients are not easy to differentiate from those who are uninfected, which means that antibiotics have to be given more often than is strictly necessary. Further research is needed to characterize those patients in whom bacterial infection has a more important role.

Acute exacerbations of chronic bronchitis: an international comparison

The prevalence of chronic bronchitis is between 3% and 17% in most developed countries. However, higher rates in the range of 13 to 27% are encountered in less developed areas of the world. Acute exacerbations of chronic bronchitis (AECB) have usually been defined as the presence of increases in cough/sputum, sputum purulence, and dyspnea. However, recent investigations suggest that the severity of AECB may be divided into three stages based on the history of the patient: (1) previously healthy individuals; (2) patients with chronic cough and sputum and infrequent exacerbations; and (3) persons with frequent exacerbations or more severe chronic airflow limitation. Therapy for patients with less severe AECB include older and less expensive broad-spectrum antibiotics, while newer agents are indicated for patients with the most severe stage of AECB.

Influence of age, gender and smoking on Streptococcus pneumoniae, Haemophilus influenzae and Moraxella (Branhamella) catarrhalis antibody titres in an elderly population

The purpose of this study was to investigate the association of serum antibody levels to Streptococcus pneumoniae, Haemophilus influenzae and Moraxella (Branhamella) catarrhalis with age, gender and smoking in an elderly population. The study population comprised all the inhabitants aged 65 years or over in a rural municipality in south-western Finland. Serum samples were obtained from 1,174 out of a total of 1,360 subjects. Bacterial antibodies were measured by enzyme immunoassay (EIA) using pneumolysin and whole bacterial cells of H. influenzae and M. catarrhalis (mixture of 10 different strains for both) as antigens. The main findings were as follows: (i) antibody levels generally decreased with increasing age both in men and in women; (ii) antibody titres against H. influenzae and M. catarrhalis were higher in men than in women; and (iii) antibody titres to H. influenzae and M. catarrhalis, but not to S. pneumoniae, were significantly higher in smokers than in non-smokers. These data suggest that antibody-mediated protection against respiratory pathogens may be impaired in the elderly, leading to a higher susceptibility to respiratory tract infections, that the exposure to H. influenzae and M. catarrhalis may be higher in men than in women, and that smokers have more respiratory infections or colonization due to these 2 bacteria than do non-smokers.

Detection of antibody-coated bacteria in expectorated sputum for diagnosis of lower respiratory infections

We evaluated antibody-coated bacteria (ACB) in expectorated sputum to discriminate contaminating or colonizing organisms from true pathogens. We examined 60 expectorated sputum samples from 51 patients with lower respiratory infections (chronic obstructive pulmonary disease 25, pneumonia 20, purulent tracheobronchitis 6). All samples were examined with quantitative culture and immunofluorescent demonstration of ACB. From the results of quantitative culture, we divided specimens into pathogen-isolated and pathogen-free samples. Among pathogen-isolated samples, in which we isolated accepted pathogenic organisms at > or = 10(7) colony-forming units per ml, 16 of 23 samples were ACB-positive (69.5%). In contrast, among pathogen-free samples, in which we isolated accepted pathogens at < 10(7) colony forming units per ml or only upper respiratory flora, only 3 of 37 samples were ACB-positive (8.1%). The ACB-positive rate was significantly higher in pathogen-isolated than in pathogen-free samples (P < 0.001). Consequently, detecting ACB in expectorated sputum shows good potential as another criterion for distinguishing contaminating or colonizing organisms from true pathogens.

Oropharyngeal flora in asthma and in chronic obstructive pulmonary disease. Indigenous oropharyngeal microorganisms in outpatients with asthma or chronic obstructive pulmonary disease

In vitro and in vivo studies have shown that various strains of "viridans streptococci" (nongroupable alpha-hemolytic streptococci) inhabiting the oropharynx suppress the growth of gram-positive and gram-negative microorganisms. We conducted an inventory of the oropharyngeal flora from ambulatory asthma and chronic obstructive pulmonary disease (COPD) patients and a control group to examine the interaction between viridans streptococci and potential pathogens in vivo. In addition, the difference in colonization patterns of these bacteria was studied. Oral washings from 195 patients, 48 asthma (24.6%), 147 COPD (75.4%), and 157 control subjects were examined microbiologically on two occasions with a 2-wk interval, resulting in a total of 384 and 295 oral washings, respectively. All patients were in a stable phase of disease throughout the study. The distribution of low (< or = 10(4)/ml) or high (> or = 10(5)/ml) concentrations of viridans streptococci did not differ substantially between asthma or COPD patients and control subjects. Potentially pathogenic microorganisms found in a low (< or = 10(4)/ml) or high (> or = 10(5)/ml) concentration were equally distributed between the two groups. Staphylococcus aureus and beta-hemolytic streptococci were found significantly less often in the asthma and COPD group (p < 0.005 and p < 0.0005, respectively), but the prevalence of Enterobacteriaceae species was significantly higher (p < 0.0005). No correlation was found between the concentration of viridans streptococci and the prevalence of gram-negative microorganisms. These findings suggest that viridans streptococci are probably not responsible for growth control of gram-negative microorganisms in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary host defenses and oropharyngeal pathogens

The lower respiratory tract is repetitively inoculated with oropharyngeal bacteria and yet pneumonia is an infrequent event. Efficient mechanisms of antibacterial defense are present in the respiratory tract that eliminate microbes before their presence or multiplication leads to disease in the majority of instances. Resident pulmonary defenses consist of aerodynamic defenses, the mucociliary apparatus, alveolar macrophages, complement, and surfactant. These resident defenses can be augmented by the development of an inflammatory response or the development of specific immunity. Significant species variability exists in the efficiency and mechanisms of clearance for oropharyngeal organisms. Streptococci are cleared promptly, Branhamella catarrhalis is cleared slowly, whereas non-typable Haemophilus influenzae multiply before being cleared. A dual phagocytic system of alveolar macrophages and recruited polymorphonuclear leukocytes is required for clearance of most oropharyngeal microbes. Systemic immunization can significantly enhance clearance of non-typable H. influenzae, suggesting immunoprophylaxis might be possible for this organism.

Effect of primary immunization on pulmonary clearance of nontypable Haemophilus influenzae

Nontypable Haemophilus influenzae (NTHI) is being increasingly recognized as a cause of both adult pneumonia and acute infectious exacerbations in chronic bronchitis. We used a mouse model to study the immune enhancement of pulmonary clearance of NTHI after a primary immunization. BALB/c mice were immunized with whole NTHI either by intraperitoneal (i.p.) or intratracheal (i.t.) routes. There was 10-fold more NTHI-directed antibody detected in the serum of the i.p.-immunized mice than in the serum from the i.t.-immunized animals. Western blot analysis revealed that these antibodies were directed against both NTHI lipooligosaccharide and the various outer membrane proteins of NTHI. The development of NTHI-directed antibodies in serum was associated with significant enhancement of early pulmonary clearance of NTHI. Six hours after delivery of an endobronchial challenge with NTHI, the i.p.-immunized mice had cleared most of the organisms from their lungs, while the i.t.-immunized mice did not clear NTHI any more rapidly than did unimmunized mice. Serum from the i.p.-immunized mice caused more than 99% uptake of NTHI in an in vitro opsonophagocytic assay, while serum from i.t.-immunized mice stimulated little or no phagocytosis of this organism. Opsonophagocytosis of NTHI was obtained with bronchoalveolar lavage (BAL) fluid collected from i.p.-immunized mice 6 h after, but not before, an endobronchial challenge with NTHI. Intravenous injection of an opsonic IgG monoclonal antibody directed against NTHI lipooligosaccharide resulted in both the appearance of this antibody in the alveolar spaces of the unperturbed lung and enhanced pulmonary clearance of NTHI. These data indicate that the i.p. (systemic) route of immunization is more effective than the i.t. route in establishing pulmonary immunity to NTHI in this model system. Furthermore, immune enhancement of clearance of NTHI from the lungs after a primary immunization apparently results from the exudation of opsonic and bactericidal antibodies from the serum into the alveolae in response to the inflammatory challenge.

Activities and sources of beta-lactamase in sputum from patients with bronchiectasis

beta-Lactamase activity was measured in secretions from patients with bronchiectasis. Of 28 sputum samples, 23 contained measurable amounts of activity; values were significantly higher (P less than 0.01) in purulent samples than in mucoid or mucopurulent samples. beta-Lactamase activity was usually present in saliva collected before and between sputum expectorations, although values for sputum were higher than for either group of saliva samples (P less than 0.025 and P less than 0.005, respectively). This difference suggests that at least part of sputum beta-lactamase activity originates in the bronchial tree. Detailed microbiological study of a further eight specimens (seven were beta-lactamase positive) led to the isolation of Haemophilus influenzae from six, although only two of these isolates were beta-lactamase positive. Several other beta-lactamase-producing organisms were also isolated, including Staphylococcus aureus (n = 3), Escherichia coli (n = 1), Proteus spp. (n = 1), and Bacteroides spp. (n = 3). Size-exclusion high-performance liquid chromatography of the sputum showed several peaks of beta-lactamase activity which usually coeluted in fractions similar to those of their beta-lactamase-positive isolates. Therefore, sources of sputum beta-lactamases are often bacteria not considered truly pathogenic or not isolated during routine bacteriological assessment. These observations should be considered when embarking on antimicrobial therapy in bronchiectatic patients and suggest that increased dosages of penicillins are indicated.

Respiratory infections may reflect deficiencies in host defense mechanisms

Serious respiratory tract infections are rare in the healthy individual and most of the nuisance morbidity that occurs results from nasopharyngeal viral infections that many people get once or twice a year. The economic impact from these upper respiratory tract infections is appreciable, however, in terms of absenteeism from school or work, but unfortunately there is little that can be done to ward them off in a practical way. Pneumonia is an infrequent lifetime experience for most non-smoking adults and when it occurs, unusual circumstances may pertain--a particularly virulent microorganism is in circulation, or perhaps one has been exposed to a newly recognized germ, such as has occurred with Legionella species in the past 8 years or so. What protects us the great majority of the time is a very effective network of respiratory tract host defenses. These include many mechanical and anatomical barrier mechanisms concentrated in nose and throat; mucociliary clearance, coughing and mucosal immunoglobulins in the conducting airways and in the air-exchange region of the alveolar structures, phagocytes, opsonins, complement, surfactant and many other factors combine to clear infectious agents. The ability to mount an inflammatory response in the alveoli may represent the maximal and ultimate expression of local host defense. In some way these host defenses are combating constantly the influx of micro-organisms, usually inhaled or aspirated into the airways, that try to gain a foothold on the mucosal surface and colonize it. But many general changes in overall health such as debility, poor nutrition, metabolic derangements, bone marrow suppression and perhaps aging promote abnormal microbial colonization and undermine the body's defenses that try to cope with the situation. It is a dynamic struggle. The departure from normal respiratory health may not be obvious immediately to the patient or to the physician and repeated episodes of infection or persisting symptoms of cough, expectoration and sinus or ear infections may develop before serious assessment of the situation is taken and appropriate diagnosis gotten underway. Obvious explanations for respiratory infections may be apparent and, nowadays, side effects from antineoplastic chemotherapy or immunosuppressive therapy for a variety of diseases that create an immunocompromised host are common. In a few subjects, especially young adults who present with a cumulative history of frequent but mild infections in childhood and youth, a subtle deficiency in host defenses may exist and have been partially masked because of attentive pediatric medical care and prompt use of broad spectrum antibiotics.(ABSTRACT TRUNCATED AT 400 WORDS)

Postmortem radiographic, histological and bacteriological studies of terminal respiratory infections and other pulmonary lesions in hospital and non-hospital necropsies

One lung from 109 unselected hospital and 43 unselected non-hospital necropsies was studied using postmortem radiography with histological verification. Signs of acute bacterial infection, including bronchiolitis or bronchopneumonia, were present in 42.2% of the hospital necropsies and infection was the immediate cause of death in 8.3%. There was only one case of incipient bronchopneumonia among the non-hospital necropsies. Emphysema was the most common other pulmonary lesion in both groups. Gram negative bacteria were found significantly more often in the bronchial mucus of lungs with any pulmonary lesion, particularly those with signs of bacterial infection, than in the bronchial mucus of morphologically normal lungs in both groups of patients. In addition, the frequency of infections was associated with length of stay in hospital. This may reflect the prevalence of Gram negative infections in hospitals.

Immunoelectronmicroscopic study on the transport of secretory IgA in the lower respiratory tract and alveoli

To define the immunocytochemical localization of secretory component (SC), IgA and J chain in human bronchioles and alveoli, a direct peroxidase-labeled antibody method was used. SC was found in non-ciliated cells of the bronchioles including respiratory bronchioles and type II alveolar epithelial cells, whereas SC was rarely present in ciliated cells and type I alveolar epithelial cells and was absent from goblet cells. In the positively reacting cells, SC was found in secretory protein synthetic organelles such as perinuclear spaces and endoplasmic reticulum, Golgi complexes, and on the external surfaces of the apical and basolateral plasma membranes. IgA and J chain were localized in the epithelial cells where SC was found. Ultrastructually IgA was present on the apical and basolateral plasma membranes, in pinocytic invaginations of the membranes, and in vesicles distributed through the cytoplasm, especially in the apical cytoplasm of the epithelial cells where SC was found. In addition, IgA and J chain were found to be associated with the endothelial cells of the capillaries, plasma cells and the surrounding interstitium. These observations suggest that SC is synthesized and secreted by epithelial cells, especially non-ciliated cells of the bronchioles including respiratory bronchioles and type II alveolar epithelial cells. They also suggest that secretory IgA (sIgA) is transported into alveolar spaces and the bronchiolar lumen through these cells by SC-mediated transport mechanism. This sIgA may play an important role in defense mechanisms of the lower respiratory tract and alveoli.

Respiratory infection complicating long-term tracheostomy. The implication of persistent gram-negative tracheobronchial colonization

Colonization of the lower respiratory tract by enteric Gram-negative bacilli (EGNB) has been a frequent finding in patients with long-term tracheostomies; however, the association of hospitalization and certain features of serious illness with this phenomenon has not been clearly established. Because such factors can render the oropharynx more susceptible to EGNB colonization, we sought to discover whether they can also have this effect on the tracheobronchial tree and its microflora. Thus, we collected serial paired culture samples from these two mucosal sites in 15 subjects with long-term tracheostomies and examined patterns and rates of colonization and related these findings to clinical parameters. In 49 sets of cultures, we found that EGNB (especially Pseudomonas species) were present in significantly fewer upper-airway cultures (36.7 percent) than lower-airway cultures (75.5 percent) (p = 0.009). At the tracheobronchial site, seven subjects had persistent EGNB colonization, all with Pseudomonas species, while only one subject had this finding at the oropharyngeal site (p = 0.015). Patients with persistent tracheobronchial colonization were more ill than those without this finding. They were treated with higher doses of prednisone (p = 0.06), received antibiotics more often, and developed purulent tracheobronchitis more often (100 percent vs 25 percent) than patients without persistent colonization. In addition, in the month following the culture survey, four subjects developed pneumonia, and three of these had previous persistent tracheobronchial colonization.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a bronchoscopic protected catheter technique in the clinical evaluation of a new antibiotic

We prospectively compared the usefulness of a bronchoscopic protected catheter technique with the results from sputum cultures in the evaluation of moxalactam, a new beta-lactam antibiotic. The significance of a given isolate on protected catheter culture was determined by quantitative bacteriology. 32 patients with community-acquired pneumonia were enrolled in the study and 31 grew common lower respiratory tract pathogens from their protected catheter specimen. The most common single pathogens recovered were Streptococcus pneumoniae (11 patients) and Haemophilus influenzae (2). Mixed flora, predominantly anaerobes, were isolated from 15 patients, and 3 patients had mixed aerobic infections. All seven bacteremic cases had the identical organism isolated from the protected catheter specimen, confirming the accuracy of the technique. Comparisons with sputum cultures showed that the predominant organism on sputum culture was the same as that obtained from the protected catheter culture in only 13% of the cases. Sputum cultures revealed either no pathogen or a different pathogen in 23 cases, and no sputum could be obtained in 4. Compared to cultures of expectorated sputum, we found the protected catheter bronchoscopic culture technique to have the following advantages in the bacteriologic evaluation of moxalactam: 1) greater accuracy and sensitivity in bacteremic patients; 2) accurate delineation of the bacteriology of infections; and 3) a higher percentage of patients with evaluable bacteriology leading to greater efficiency during the investigation.

Bacteriology of the maxillary sinus of rhesus monkeys

Quantitative cultures of transantral aspirates of the maxillary sinuses of rhesus monkeys were performed to determine whether the sinuses have a normal bacterial flora. Of 13 sinus aspirate cultures 11 (85%) were sterile. The two positive sinus aspirate cultures had extremely low colony counts of the same bacteria present on the nasal mucosa prior to the sinus puncture. The maxillary sinuses of rhesus monkeys are sterile.

Pneumonia with bacteraemia due to Escherichia coli

Pneumonia due to Escherichia coli (E. coli) has a reported mortality of up to 70 per cent. Most infections are associated with underlying disease, and follow bacteraemia from a genitourinary or gastrointestinal source. This report describes two patients with bacteraemic E. coli pneumonia, presumed secondary to aspiration of E. coli from the oropharynx. Both patients presented a rapidly progressive illness with hypotension. Response of the pneumonia to early, appropriate antimicrobial therapy, was complete. Our cases are discussed with particular reference to clinical features of the infection and choice of antimicrobial therapy.

Sampling lower respiratory tract secretions in primary lung abscess: a comparison of the accuracy of four methods

To determine the relative cultural accuracy of transtracheal aspiration (TTA), wire-brushing under direct vision through a flexible fiberoptic bronchoscope (WBB), and expectorated sputum (ES) in localized pulmonary infections, we compared each method with percutaneous needle lung aspiration (PLA) cultures in patients with peripheral lung abscesses. Of the 27 organisms that PLA cultures isolated from ten lung abscesses (eight aerobic, two anaerobic), TTA identified 81 percent plus an additional five, and WBB 68 percent plus 16. Of the 14 organisms that PLA cultures isolated from eight aerobic abscesses, TTA identified 93 percent plus an additional two, WBB 83 percent plus 12, and ES 71 percent plus 19. From a laboratory standpoint, we concluded the following: (1) when PLA cultures cannot be obtained, the most accurate method for determining the cause of a localized pulmonary infection is TTA generates false-negative and false-positive information, it may not be an appropriate standard to evaluate other methods, such as ES.