Comparison of four methods for assessing airway bacteriology in intubated, mechanically ventilated patients

A prospective evaluation of lower airway bacteriology from intubated, mechanically ventilated patients was performed by comparing the qualitative and quantitative recovery of bacteria using four different techniques. Twelve intubated, mechanically ventilated patients who satisfied accepted clinical criteria for the suspicion of ventilator-associated pneumonia were studied. Airway secretions were obtained from each patient by: (1) blind endotracheal aspiration (ET); (2) Accu-cath pulmonary culture catheter (Accu); (3) bronchoscopic protected specimen brush (BPSB); and (4) bronchoalveolar lavage (BAL). ET specimens were cultured semi-quantitatively (1+ to 4+) aerobically, and all other specimens were cultured quantitatively both aerobically and anaerobically. The BPSB recovered 9 organisms in > or = 10(3) colony forming units/ml, a standard number often used to indicate significant growth. Of these 9 organisms, 7 were recovered at > or = 10(3) cfu/ml by Accu, and 6 were recovered at > or = 10(4) cfu/ml by BAL. All 8 aerobic isolates recovered in > or = 10(3) cfu/ml by BPSB also were recovered by ET aspirate. Five of these were recovered in > or = 3+ semi-quantitative growth by ET aspirate. Of 30 organisms recovered in < 3+ semi-quantitative growth by ET aspirate, 28 were recovered in < 10(3) cfu/ml by BPSB, indicating a negative predictive value of 93%. Thus, it appears that these four methods provide reasonably similar qualitative and quantitative recovery of bacteria from the lower airways of intubated, mechanically ventilated patients. In addition, routine Gram's stain and semi-quantitative aerobic culture of endotracheal aspirate may provide useful information in patients with suspected ventilator-associated pneumonia.

Respiratory tract colonization with Ureaplasma urealyticum and bronchopulmonary dysplasia in neonates in southern Israel

Ureaplasma urealyticum has been recognized as an important potential pathogen in premature neonates. Reported rates of colonization of the respiratory tract vary. Data on neonatal ureaplasma colonization outside the United States and Western Europe are rare. Therefore we prospectively studied nasopharyngeal and endotracheal colonization in a cohort of 114 preterm and 100 full term infants within 48 hours of birth. The colonization rate was 24% in the premature infants and zero in the full term infants. Bronchopulmonary dysplasia developed in 19% of infants with nasopharyngeal Ureaplasma colonization and in 4.6% of noncolonized infants (P < 0.03). Bronchopulmonary dysplasia developed in 40% of intubated infants with positive endotracheal Ureaplasma cultures and only in 9.8% of infants with negative endotracheal cultures (P < 0.04). Thus Ureaplasma colonization of either the nasopharynx or the trachea was associated with an increased risk for the development of bronchopulmonary dysplasia (relative risk, 4.0 and 4.1, respectively).

Microbial flora of the trachea during intubation of patients undergoing upper abdominal surgery

BACKGROUND

The presence of Haemophilus influenzae in the oropharynx is correlated with the subsequent development of chest infection. The importance of colonisation of the trachea by bacteria at the time of surgery is uncertain. This study investigated the tracheal flora at the time of intubation in 24 patients undergoing elective upper abdominal surgery.

METHODS

The bacterial flora of the trachea was sampled in all 24 patients immediately after intubation and immediately before extubation. Patients were assessed postoperatively for the development of chest infection.

RESULTS

Bacteria, including H influenzae in five cases, were isolated from the post-intubation brushings of the trachea of 15 patients. The pre-extubation brushings from only four patients yielded growth. Three of five patients developing a chest infection were colonised by H influenzae according to the postintubation brush, compared with two of 19 without chest infections. Before extubation two of five developing chest infections had H influenzae in the trachea but none of 19 without infection. All but one of the patients from whom H influenzae was isolated were smokers.

CONCLUSIONS

These results suggest that the increased risk of postoperative chest infection in cigarette smokers may be due in part to colonisation of the trachea by H influenzae at the time of operation.

Demonstration of sites of latency of infectious laryngotracheitis virus using the polymerase chain reaction

Mature laying chickens were inoculated intratracheally with a field strain of infectious laryngotracheitis (ILT) virus. Tracheal swabs were collected regularly from all birds for virus culture. At various times post-inoculation, pairs of birds were killed and tissues removed for detection of virus products using conventional tissue homogenization and culture, organ culture, indirect immunofluorescence (IF) and also the polymerase chain reaction (PCR). The latter was used to detect a DNA sequence from the ILT virus thymidine kinase gene. Following inoculation the birds developed mild respiratory disease with clinical signs characteristic of ILT from 3 to 10 days post-inoculation. Trachea and turbinate tissues were virus-positive as determined by virus isolation, organ culture, IF and PCR on day 4 post-inoculation. After recovery from the acute phase, virus shedding initially ceased, then intermittent, low level shedding was recorded for five of the six remaining birds. In an attempt to locate sites of latency, pairs of birds were sampled at 31, 46 and 61 days post-inoculation. Virus was not detected in upper respiratory tract or ocular tissues by conventional techniques, or in the trigeminal, proximal and distal ganglia. All tissues were also negative by PCR, except for the trigeminal ganglia of five of the six birds. All PCR-positive birds had previously shed ILT virus intermittently between days 19 and 59 post-inoculation. As we did not detect viral DNA in any of the other tissues sampled from clinically recovered birds, we conclude that the trigeminal ganglion is the main site of latency of ILT virus.

Effect of cyclophosphamide immunosuppression on the immunity of turkeys to viral rhinotracheitis

Turkey poults, free of antibodies to turkey rhinotracheitis (TRT) virus were treated with cyclophosphamide on days 1, 2 and 3 after hatching and vaccinated by eyedrop when 10 days old with a Vero cell-attenuated preparation of TRT virus. No ELISA antibodies to TRT virus developed in the sera of these poults but they were as resistant to virulent virus challenge 21 days later as vaccinated groups which were not cyclophosphamide-treated but produced humoral antibodies. Following challenge with virulent virus at 31 days old cyclophosphamide-treated unvaccinated poults developed a more severe clinical response than untreated birds and had higher virus titres in tracheal swabs. The findings show that the respiratory tract of turkeys may be resistant to TRT despite the absence of ELISA antibodies in the serum.

Enhanced adherence of Pasteurella multocida to porcine tracheal rings preinfected with Bordetella bronchiseptica

Adherence of 25 isolates of Pasteurella multocida to porcine tracheal rings was evaluated. Results indicated that adherence was not related to the isolate's origin, capsular or somatic types, dermonecrotoxin production or hemagglutination activity. The effect of a preinfection with Bordetella bronchiseptica on the colonization by P. multocida was then studied. On rings infected with P. multocida alone, bacteria initially adhered to the epithelium, but within a few hours, the level of colonization decreased progressively. On rings preinfected with B. bronchiseptica, or pretreated with a cell-free B. bronchiseptica culture supernate (or filtrate), a high level of P. multocida colonization was maintained for at least 24 hours. Results indicate that B. bronchiseptica appears to facilitate upper respiratory tract colonization by P. multocida by a process which involves a low molecular weight (less than or equal to 1000) heat-stable substance, possibly the tracheal cytotoxin.

Experimental pathogenicity of Mollicutes of bovine udder origin in hamster tracheal ring organ culture

Hamster tracheal-ring organ culture was employed to examine pathogenic effects of 8 isolates of Mollicutes of bovine udder origin. The tested Mollicutes could be categorized into two groups: (i) Mycoplasma F-38, M. mycoides var. capri, M. bovigenitalium mixed with M. bovirhinis, and M. bovigenitalium mixed with M. bovirhinis and Mycoplasma F-38 produced significant ciliostatic effect and infiltration of neutrophils and lymphocytes in lamina propria/subepithelium, hyperplasia and desquamation of epithelial lining cells and loss of cilia; and (ii) A. laidlawii, A. axanthum, an unidentified Acholeplasma and a mixed isolate of M. bovis, M. bovigenitalium, Mycoplasma F-38 and A. laidlawii showed insignificant ciliostatic effects and produced mild histopathological lesions. This correlates with the disease causing potentials of the strains.

Definition and application of a histopathological scoring scheme for an animal model of acute Mycoplasma pneumoniae pulmonary infection

A histopathological scoring system was developed to assess the pathology of acute Mycoplasma pneumoniae pulmonary infection in a hamster model. A final score per animal (ranging 0-26) is obtained by averaging scores from each lung which have been accumulated by the addition of subscores from the assessments of quantity and quality of peribronchiolar and peribronchial infiltrates, luminal exudates, perivascular infiltrates, and parenchymal pneumonia. The scoring scheme was then applied to test the ability of a heat-killed inoculum to induce pulmonary pathology and to the trial of a 43 kDa protein-associated antigen as a vaccine immunogen. A heat-killed inoculum delivered by both intratracheal and intranasal routes did not induce pulmonary pathology compared to a live inoculum (respective mean scores 0.1, 6.7; P less than 0.01). Animals prevaccinated with the 43 kDa antigen developed an accentuated pathological response after live challenge compared to those unvaccinated (respective mean scores 16.8, 5.8; P = 0.00007). Hypersensitization to growth medium components may, however, have contributed to the accentuated disease since the lungs of vaccinated animals challenged with culture-negative media also were affected (mean score 5.4). Reproducibility of the scoring system was measured by duplicate reading of histology slides which were randomized to the observer upon the second reading (r = 0.93; P = 0.000009). The scoring system has the ability to differentiate disease severity in small groups of animals.

Pulmonary aspiration of gastric contents in patients receiving mechanical ventilation: the effect of body position

OBJECTIVE

To determine if the semirecumbent position (45-degree angle) decreases aspiration of gastric contents to the airways in intubated and mechanically ventilated patients.

DESIGN

A randomized, two-period crossover trial.

SETTING

Respiratory intensive care unit.

PATIENTS

Nineteen patients requiring intubation and mechanical ventilation.

INTERVENTIONS

Patients were studied in the supine and semirecumbent positions on two separate days.

MEASUREMENTS

After technetium (Tc)-99m sulphur colloid labeling of gastric contents, sequential radioactive counts in endobronchial secretions were measured at 30-minute intervals over a 5-hour period. Samples of endobronchial secretions, gastric juice, and pharyngeal contents were obtained for qualitative bacterial cultures.

RESULTS

Mean radioactive counts in endobronchial secretions were higher in samples obtained while patients were in the supine position than in those obtained while patients were in the semirecumbent position (4154 cpm compared with 954 cpm; P = 0.036). Moreover, the aspiration pattern was time-dependent for each position: For the supine position, radioactivity was 298 cpm at 30 min and 2592 cpm at 300 min (P = 0.013); for the semirecumbent position, radioactivity was 103 cpm at 30 min and 216 cpm at 300 min (P = 0.04). The same microorganisms were isolated from stomach, pharynx, and endobronchial samples in 32% of studies done while patients were semirecumbent and in 68% of studies done while patients were in the supine position.

CONCLUSIONS

We conclude that the supine position and length of time the patient is kept in this position are potential risk factors for aspiration of gastric contents. Elevating the head of the bed for patients who can tolerate the semirecumbent position may be a simple, no-cost prophylactic measure.

Adherence to respiratory epithelia by recombinant Escherichia coli expressing Klebsiella pneumoniae type 3 fimbrial gene products

We examined the role of Klebsiella fimbrial types 1 and 3 in mediating adherence to human buccal and tracheal cells and to lung tissue sections. We found that clinical isolates of Klebsiella pneumoniae producing type 3 fimbriae and Escherichia coli HB101 containing a recombinant plasmid encoding expression of Klebsiella type 3 fimbriae (pFK10) demonstrated increased adherence to tracheal cells, trypsinized buccal cells, and lung tissue sections, in contrast to nonfimbriate and to type 1 fimbriate bacteria. Adherence by type 3 fimbriate bacteria was inhibited by purified type 3 fimbriae and Fab fragments derived from type 3 fimbrial-specific polyclonal immunoglobulin G. Type 3 fimbriae mediated attachment to the basolateral surface of tracheal cells and to the basal epithelial cells and the basement membrane regions of bronchial epithelia. Using an E. coli transformant (pDC17/pFK52), which expresses nonadherent P fimbrial filaments, along with the type 3 fimbrial adhesin (MrkD), we demonstrated that type 3 fimbrial attachment to respiratory cells was attributable to the MrkD adhesin subunit. Subsequent experiments demonstrated that the epithelial target of the type 3 fimbrial adhesin was most likely a peptide molecule rather than a carbohydrate. The results of this study demonstrate that, in vitro, the Klebsiella type 3 fimbrial adhesin mediates adherence to human respiratory tissue.

Bacterial flora of the respiratory tracts in chickens with a particular reference to Lactobacillus species

The effects of three different types of breeding such as isolator, floor, and cage breedings on the bacterial flora of the respiratory tracts (nasal cavity, tongue, pharygolarynx, trachea and air sac) in chickens were determined. Total viable bacterial numbers on the nasal mucus of chickens in the isolator breeding as control group (Group A) aged of 14 days were 10(4.6)/g of autopsy specimen (wet weight), 10(5.7)/g of sample in the cage breeding (Group B) aged of 28 days, and 10(7.0)/g of sample in the floor breeding (Group C) aged of 28 days. Staphylococci and micrococci were predominant bacteria in the nasal cavities of all groups. Total viable numbers of tongue and pharygolarynx were from 10(5.4) to 10(6.5)/g of autopsy specimen. Lactobacilli were the predominant bacteria in pharyngolarynx of chickens. The incidence of staphylococci and micrococci in trachea was lower than those in the another regions. Staphylococci and micrococci dominated in the air sacs of two groups (B and C), but the number and incidence of lactobacilli in the air sacs of chickens were lower than those in the another respiratory tracts. The only clostridia isolation in the air sacs of Group A was observed. A total of 75 strains of Lactobacillus species was isoalted from all respiratory organs and intestine of chickens. These strains were divided into 19 groups. Lactobacillus salivearius subsp. salivarius was the predominant lactobacilli isolated from tongue and pharyngolarynx. Most of isolates from the chicken intestines were mainly identified as the L. acidophilus group and L. reuteri.(ABSTRACT TRUNCATED AT 250 WORDS)

Mycoplasma gallopavonis in eastern wild turkeys

Serum samples and tracheal cultures were collected from eastern wild turkeys (Meleagris gallopavo sylvestris) trapped for relocation in South Carolina (USA) during 1985 to 1990. Sera were tested for Mycoplasma gallisepticum and M. synoviae by the rapid plate agglutination and hemagglutination inhibition tests and were found to be negative. Tracheal cultures were negative for all pathogenic Mycoplasma spp., including M. gallisepticum, M. synoviae, M. meleagridis, and M. iowae. However, M. gallopavonis was isolated from every group of wild turkeys tested in 1986 to 1990. These data suggest that M. gallopavonis, which is generally considered nonpathogenic, may be a common microorganism in eastern wild turkeys.

Electron microscopic observation of the respiratory tract of SPF piglets inoculated with Mycoplasma hyopneumoniae

Seven hysterectomy derived piglets were repeatedly challenged with Mycoplasma hyopneumoniae during the first week of life. Samples of trachea, bronchi and lung tissue collected 2-11 weeks post-inoculation (p.i.) were examined using light and electron microscopy. Autoradiography was used to study in more detail the site of M. hyopneumoniae multiplication. Gross lesions were observed in lung tissue and were characterized by hyperplasia of the epithelium and an increased mononuclear cell accumulation in perivascular and peribronchiolar areas. Mild lesions of the trachea and the bronchi, including epithelial hyperplasia and infiltration of the lamina propria by inflammatory cells, were noted. Electron microscopy showed that, 2-6 weeks p.i., changes in the mid-trachea and bronchi surface consisted of the loss of cilia. Mycoplasmas covered tufts of cilia remaining on the epithelial cell surface. Scanning and transmission electron micrographs showed that they were predominantly found closely associated with the top of cilia. No specialized terminal structure could be seen and no mycoplasma cells were identified lying free in the lumen nor in close contact with the plasma membrane of cells or microvilli. Some fine fibrils radiating from one mycoplasma to another or to cilia were seen at higher magnification by scanning electron microscopy. Six to eleven weeks p.i., a disrupted epithelial surface lacking cilia was observed. Cells were desquamated and shed into the lumen with cellular remains containing droplets of mucus. Autoradiography revealed that label corresponded to the observed mycoplasma distribution. At the top of cilia, a high density of labeling was visible in the zone of high mycoplasma concentration. Therefore, incorporation of the label in the mycoplasma is proof or their multiplication in the trachea. The intimate association between the mycoplasma and cilia may be an important factor in the pathogenesis of the disease caused by M. hyopneumoniae (swine enzootic pneumonia).

Viral tracheitis in goslings in Saskatchewan

Up to 12% mortality occurred in goslings between 4 and 11 days of age in two sequential hatches from a single breeder flock. Respiratory signs were noted before the birds died. The most consistent necropsy finding was a white opaque plug of fibrin and cellular debris in the trachea. The tracheal epithelium was hyperplastic and metaplastic with intranuclear inclusion bodies present in superficial cells. An adenovirus was isolated in both chicken and goose embryo liver cells.

Recombinant P.69/pertactin: immunogenicity and protection of mice against Bordetella pertussis infection

The immunogenicity of recombinant (r-) pertactin was examined. Parenteral immunization of mice with natural or r-pertactin produced a similar increase in serum anti-pertactin antibodies and a decrease in Bordetella pertussis lung counts following aerosol challenge. Study of the kinetics of B. pertussis growth in the respiratory tract of immunized and control mice revealed that immunization with r-pertactin halted the multiplication of B. pertussis in the lungs and facilitated the early onset of bacterial clearance. In the trachea, bacterial numbers declined sharply in immunized animals during the first 3 days after challenge but thereafter B. pertussis numbers remained fairly constant throughout the rest of the experiment. Very low doses (0.1 micrograms) of r-pertactin were immunogenic and protective but only if the antigen was absorbed to alhydrogel. In vitro proliferation assays with lymphocytes from mice primed with either natural or r-pertactin indicated that the major T-cell epitopes of pertactin are conserved in the recombinant protein.

Release of mucus glycoconjugates by Pseudomonas aeruginosa rhamnolipid into feline trachea in vivo and human bronchus in vitro

Pseudomonas aeruginosa colonizes the lower respiratory tracts of patients with severe bronchiectasis, including cystic fibrosis, a condition associated with increased airway mucus output. We have shown that an extract containing chloroform-soluble extracellular products of P. aeruginosa releases glycoconjugates into the cat trachea in vivo. This activity was not related to pyocyanin, a major component of the extract, but was associated with the rhamnolipids. Purified monorhamnolipid (100 micrograms/ml) released radiolabeled and periodic acid-Schiff (PAS)-reactive glycoconjugates (delta 3H = +490 +/- 70%, delta 35S = +170 +/- 40%, delta PAS = +8.6 +/- 1.7 micrograms/min; n = 6, P less than 0.02 for each). Dirhamnolipid (200 micrograms/ml) was also effective (delta 3H = +640 +/- 70%, delta 35S = +130 +/- 20%, delta PAS = +9.3 +/- 1.5 micrograms/min; n = 6, P less than 0.02 for each). Monorhamnolipid (100 micrograms/ml) also released 35S-labeled and PAS-reactive glycoconjugates from human bronchial tissue in vitro (delta 35S = +189 +/- 47%, delta PAS = +26.3 +/- 8.5 micrograms/min; n = 7, P less than 0.001 versus control tissues in which no stimulus was given). The cat tracheal glycoconjugates released by the rhamnolipids differed from those released by pilocarpine 50 microM, in having a higher 3H:35S ratio (P less than 0.001). After gel chromatography on a Sepharose CL-4B column, the void volume fractions of the glycoconjugates also had different profiles in a cesium chloride density gradient. Those released by rhamnolipid banded at 1.62 g/ml, while those released by pilocarpine banded mainly at 1.50 g/ml, with some of the higher density material also present.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Pseudomonas aeruginosa adherence to cultured hamster tracheal epithelial cells

This study reports an in vitro system that allows the convenient study of both microenvironmental and bacterial factors affecting adherence of Pseudomonas aeruginosa to tracheal epithelium. Primary cultures of mixed ciliated and nonciliated epithelial cells isolated from hamster tracheas were grown on collagen-coated multiwell plates containing 10(5) epithelial cells/well at confluence. When 10(7) 14C-labeled P. aeruginosa (nonmucoid, strain Y-4) suspensions were added to each well, 8.13 +/- 2.6% (mean +/- SD) of the initial inoculum bound to the cultured cells, an amount comparable to that measured using suspensions of human tracheal epithelial cells and the same bacteria. The bacteria adhered preferentially to the cultured cells rather than to an acellular collagen matrix. Five additional nonmucoid strains of P. aeruginosa also bound well to the cultured cells, while two mucoid strains were less adherent. Strains of two other gram-negative bacteria, Pseudomonas maltophilia and Klebsiella pneumoniae, did not bind significantly, emphasizing the bacterial species specificity of the adherence interaction being measured. The binding interaction with P. aeruginosa was both pH-sensitive and altered by the presence of the divalent cation calcium. Thus, the in vitro assay system described provides a consistent surface of tracheal epithelial cells that binds P. aeruginosa in a specific manner and can be used to examine the effects of bacterial variables and microenvironmental conditions that may be present in the human airway.

Effect of respiratory tract viral infection on murine airway beta-adrenoceptor function, distribution and density

1. The effects of a respiratory tract viral infection on beta-adrenoceptor density, distribution and function were investigated in murine airways. 2. Following intranasal inoculation of CBA/CaH mice with influenza A/PR-8/34 virus, the virus proliferated rapidly in trachea (peak titres 2 days post-inoculation) and lung (peak titres 4-6 days post-inoculation). Respiratory tract viral infection was associated with a significant increase in lung weight (88% higher than control mice at day 6 post-inoculation) that was related temporally to the development of peripheral lung inflammation and consolidation. 3. Analysis of specific binding of [125I]-cyanopindolol to beta-adrenoceptors revealed that on days 2, 4 and 8 post-inoculation with virus, mouse isolated tracheal sections contained, on average, 40% more beta-adrenoceptors than tracheal sections from time matched control mice. Subsequent quantitative autoradiographic studies demonstrated that this increase in total tracheal beta-adrenoceptors was due primarily to a 90% increase in the density of beta-adrenoceptors in the tracheal epithelium in virus-infected mice. 4. In contrast, virus-infection had no significant effect on the density of beta-adrenoceptors in tracheal airway smooth muscle, although within 2 days of inoculation with virus, mouse tracheal smooth muscle segments were approximately 2 fold less sensitive to the beta-adrenoceptor agonist, noradrenaline (mean pD2 = 6.57 +/- 0.04, n = 24) and to the adenylyl cyclase-activator forskolin (mean pD2 = 6.78 +/- 0.04, n = 12) compared to segments from control mice (mean pD2 = 6.84 +/- 0.06 for noradrenaline; mean pD2 = 7.03 +/- 0.07 for forskolin). Similar values were obtained 8 days post-inoculation. At day 2, but not day 8 post-inoculation with virus, relaxation responses to theophylline were also marginally attenuated compared with controls.5. Mouse isolated tracheal segments obtained 2 days after virus inoculation and segments from timematched control mice were equisensitive to the spasmogenic actions of the muscarinic cholinoceptor agonist, carbachol. However, tracheal segments from mice inoculated with virus were less responsive to carbachol on day 4 (mean pD2 = 6.45 + 0.04, n = 8) and day 8 (mean pD2 = 6.45 +/- 0.02, n = 12) compared to control preparations (day 4, mean pD2 = 6.73 +/- 0.06, n = 8; day 8, mean pD2= 6.65 +/- 0.04, n = 12, P < 0.05). In contrast, endothelin-l-induced contractions of tracheal smooth muscle were notaffected by virus-infection.6. These data demonstrate that respiratory tract viral infection can produce significant tissue-selective changes in airway /beta-adrenoceptor density as well as small reductions in airway smooth muscle muscarinic cholinoceptor and /beta-adrenoceptor function.

[Bacteriological studies on pharyngeal and tracheal colonization in patients of operations and patients in ICU]

Bacterial colonization of the pharynx before and one week after operation, and contamination of the trachea during intubation in 7 patients who underwent operations were investigated. And bacterial colonization of pharynx, tracheas, and mechanical-ventilators in 7 ICU patients was investigated. Flora of palms of 10 ICU personnel was also examined: 1) Oral bacteria began to be found in the trachea several hours after intubation. 2) In oropharyngeal flora, one week after operation, Neisseria and anaerobes which belong to normal flora decreased because of antibiotics, but no new resistant bacteria appeared. 3) Although isolates from pharynx of preoperative patients were normal flora, those of ICU patients were Staphylococcus epidermidis, Enterococcus spp., gram-negative rods such as Pseudomonas aeruginosa, and yeast liked organisms etc, which were resistant to antibiotics. 4) From the trachea of intubated patients in ICU, oral bacteria were isolated. 5) Pseudomonas pickettii was isolated from the expiratory side of ventilator circuits in one patient, but it was not isolated from the patient. 6) From hands of ICU personnel, gram-positive bacteria such as coagulase negative staphylococci, Coryne bacterium spp. and Bacillus spp. were isolated. 7) One patient in ICU, who developed pneumonia due to resistant Bacteroides fragilis following oropharyngeal colonization, was reported. These studies suggested the importance of environmental control, careful selection of antibiotics, and attention to change of flora.

In vitro binding of Pasteurella multocida cell wall preparations to tracheal mucus of cattle and swine and to a tracheal epithel cell wall preparation of cattle

Outer membrane preparations of various Pasteurella isolates (Pasteurella multocida and some other Pasteurella species) from cattle and swine were extracted by N-lauryl-sarcosine sodium salt. Capsular extracts were prepared by heat treatment. Both preparations bound to epithel cell wall preparations (ECW) of trachea from cattle and to tracheal mucus of cattle and swine. Binding was demonstrated by an enzyme-linked immunosorbent assay (ELISA). Distinct high adherence values were shown by the greater part of membrane preparations of mucoid Pasteurella strains, especially when originating from cattle.

Pathogenesis of Aujeszky's disease virus infection in swine tracheal organ culture

Two different strains of Aujeszky's disease virus (ADV) were inoculated into swine tracheal organ culture. Both viruses replicated in and destroyed the tracheal epithelium and epithelial cells. ADV antigen was first localized in ciliated epithelial cells by fluorescent antibody and immunoperoxidase examinations. Corresponding to the distribution of ADV antigen, many ADV particles were observed in ciliated epithelial cells. Results demonstrated that the tracheal epithelium infected with ADV is reduced in its ciliary activity.

Environmental contamination during tracheal suction. A comparison of disposable conventional catheters with a multiple-use closed system device

The extent of airborne environmental bacterial contamination which occurs following tracheal suction has been investigated in patients undergoing intermittent positive pressure ventilation in the intensive therapy unit. Two methods of performing suction, one using a conventional open technique and one using a closed system (Stericath), have been compared. Significantly lower levels of environmental contamination were observed when the closed system was used.