Clinical predictors of hypoxaemia in Gambian children with acute lower respiratory tract infection: prospective cohort study

OBJECTIVES: To determine clinical correlates and outcome of hypoxaemia in children admitted to hospital with an acute lower respiratory tract infection. DESIGN: Prospective cohort study. SETTING: Paediatric wards of the Royal Victoria Hospital and the hospital of the Medical Research Council's hospital in Banjul, the Gambia. SUBJECTS: 1072 of 42 848 children, aged 2 to 33 months, who were enrolled in a randomised trial of a Haemophilus influenzae type b vaccine in the western region of the Gambia, and who were admitted with an acute lower respiratory tract infection to two of three hospitals. MAIN OUTCOME MEASURES: Prevalence of hypoxaemia, defined as an arterial oxygen saturation <90% recorded by pulse oximetry, and the relation between hypoxaemia and aetiological agents. RESULTS: 1072 children aged 2-33 months were enrolled. Sixty three (5.9%) had an arterial oxygen saturation <90%. A logistic regression model showed that cyanosis, a rapid respiratory rate, grunting, head nodding, an absence of a history of fever, and no spontaneous movement during examination were the best independent predictors of hypoxaemia. The presence of an inability to cry, head nodding, or a respiratory rate >/= 90 breaths/min formed the best predictors of hypoxaemia (sensitivity 70%, specificity 79%). Hypoxaemic children were five times more likely to die than non-hypoxaemic children. The presence of malaria parasitaemia had no effect on the prevalence of hypoxaemia or on its association with respiratory rate. CONCLUSION: In children with an acute lower respiratory tract infection, simple physical signs that require minimal expertise to recognise can be used to determine oxygen therapy and to aid in screening for referral. The association between hypoxaemia and death highlights the need for early recognition of the condition and the potential benefit of treatment.     

A clinical study of respiratory infection isolating non-pathogenic Neisseria by transtracheal aspiration]

Neisseria species other than N. meningitidis and N. gonorrhoeae are generally regarded as commensal bacterial flora of the oropharynx, and little is known regarding cases of these non-pathogenic Neisseria species in the lower respiratory tract. We clinically examined respiratory tract infections from which non-pathogenic Neisseria species were isolated by transtracheal aspiration (TTA). The incidence of non-pathogenic Neisseria isolated was 54 (15.7%) out of 344 episodes of respiratory tract infections with isolated microorganisms from TTA, and was 17.6%, 15.8%, 14.3% for pneumonia, acute bronchitis, and chronic lower respiratory tract infection, respectively. All 54 episodes were isolated with other microorganisms such as alpha-Streptococcus spp. (75.9%), Haemophilus influenzae (25.9%) and anaerobics (22.2%). The isolation ratio according to the age group increased at 45 years of age or more, but did not increase with the advance of age. Predisposing factors were identified such as overt aspiration, iatrogenic procedure and heavy smoking. Cases without overt aspiration that had fevers of 38 degrees C or more or hypoxemia of less than PaO2 70 torr when detecting non-pathogenic Neisseria were observed more frequently in the aged than the non-aged. The findings suggest the detection of non-pathogenic Neisseria by TTA is influenced by the host state that the fall of microorganisms from the upper to lower respiratory tract cannot be defended or excluded by mucociliary transportation disorder due to underlying disease and smoking, or deterioration of physical status other than overt or silent aspiration.     

Clinical significance and outcome of anaerobic bacteremia

We retrospectively studied the incidence of anaerobic bacteremia during 6 years (1991-1996) at Turku University Central Hospital (Turku, Finland). The clinical significance of a positive anaerobic blood culture, the effect of a positive culture on the choice of antimicrobial therapy, and the outcome for patients were evaluated. Cultures of blood from 81 patients yielded anaerobic bacteria (4% of all bacteremias). Anaerobic bacteremia was clinically significant in 57 patients (0.18 cases per 1,000 admissions). Only half (28) of these patients received appropriate and effective antimicrobial treatment before the results of blood cultures were reported; for 18 patients (32%), initially ineffective treatment was changed on the basis of the bacteriologic results, and for 11 patients (19%), the treatment was not changed. The mortality in these patient groups was 18%, 17%, and 55%, respectively. Empirical therapy may provide coverage for anaerobes in only half of the patients with anaerobic bacteremia, and failure to pay attention to the results of anaerobic blood cultures may have serious consequences for patients.     

Mycobacteria as pathogens of respiratory infection

As the result of a formidable effort, the recent TB epidemic in the United States has abated; however, major questions remain as the risk of TB diminishes. Will we maintain an adequate public health effort not only to prevent another resurgence of TB but also to renew our pursuit of TB elimination? Do we have the will to extend the fight against TB worldwide as the TB threat in the United States declines? What is the best way to incorporate new diagnostic technology into routine practice? What are the best strategies for preventing and treating TB in AIDS patients? From the standpoint of NTM lung diseases, the major challenges are to educate clinicians about the variety and clinical presentation of NTM lung pathogens in order to recognize NTM lung disease as early as possible and to maximize treatment options. Hopefully, we can also improve upon the recent unprecedented progress in treatment regimens for NTM diseases of all types.     

A clinical study of chronic lower respiratory infection with Haemophilus influenza by transtracheal aspiration

We have performed a clinical study on chronic lower respiratory tract infection (CLRTI) with Haemophilus influenzae (H. influenzae) by transtracheal aspiration (TTA) and analyzed clinical factors of the acute exacerbation. In 40 episodes (38 cases) of H. influenzae isolated from CLRTI, monobacterial infection with H. influenzae were 21 episodes and polymicrobial infection were 19 episodes. We classified the disease into acute exacerbated (27 episodes) and stable (13 episodes) phase and the former episodes were divided into bronchitis type (7 episodes) and pneumonia type (20 episodes). Polymicrobial infections were seen more in the pneumonia type (13 episodes) than in the bronchitis type (2 episodes). The principal organism detected with H. influenzae were alpha-Streptococcus and Neisseria sp. in the bronchitis type and S. pneumoniae in the pneumonia type. The acute exacerbated cases were divided into the following 4 patterns; 1. polymicrobial infection with continuous infection of P. aeruginosa, 2. monomicrobial infection after acute upper respiratory tract infection, 3. polymicrobial infection with S. pneumoniae after continuous infection of H. influenzae, 4. bacterial replacement by P. aeruginosa after acute exacerbation. The results of the study suggests that polymicrobial infection is an important chronic lower respiratory tract infection when caused H. influenzae.     

Aerobic and anaerobic microbiology of surgical-site infection following spinal fusion

The aerobic and anaerobic microbiology of surgical-site infections (SSI) following spinal fusion was retrospectively studied. This was done by reviewing the clinical and microbiological records at the Naval Hospital in Bethesda, Md., from 1980 to 1992. Aspirates of pus from 25 infection sites showed bacterial growth. Aerobic bacteria only were recovered from 9 (36%) specimens, anaerobic bacteria only were recovered from 4 (16%), and mixed aerobic and anaerobic bacteria were recovered from 12 (48%). Sixty isolates were recovered: 38 aerobes (1.5 isolates per specimen) and 22 anaerobes (0.9 isolate per specimen). The predominant aerobes were Escherichia coli (n = 8) and Proteus sp. (n = 7). The predominant anaerobes were Bacteroides fragilis group (n = 9) and Peptostreptococcus sp. (n = 6) isolates. An increase in recovery of E. coli and B. fragilis was noted in patients with bowel or bladder incontinence. This study highlights the polymicrobial nature of SSI and the importance of anaerobic bacteria in SSI following spinal fusion.     

Animal models of respiratory syncytial virus infection

Over the past two decades, animal models of respiratory syncytial virus (RSV) infection have been developed using primates, cotton rats, mice, calves, guinea pigs, ferrets, and hamsters. Use of these models has shed light on the mechanisms of vaccine-enhanced disease seen in clinical trials of a formalin-inactivated RSV vaccine and has provided a means for testing efficacy and safety of candidate prophylactic and therapeutic strategies. The development of multiple animal models has coincided with the realization that RSV disease in humans is a multifaceted disease whose clinical manifestations and sequelae depend upon age, genetic makeup, immunologic status, and concurrent disease within subpopulations. There is no single human subpopulation in whom all forms of RSV disease manifest, nor is there a single animal model that duplicates all forms of RSV disease. The choice of an experimental model will be governed by the specific manifestation of disease to be studied.     

Functional relevance of anaerobic metabolism in the isolated respiratory network of newborn rats

Respiratory (C3-C5) activity and extracellular K+, pH and Ca2+ (aKe, pHe, [Ca]e, respectively) in the ventral respiratory group (VRG) were measured in vitro. In brainstem-spinal cord preparations from 0- to 1-day-old rats, lowering of bath glucose content from 30 to 10 mM for 1 h did not affect aKe or rhythmic activity. In preparations from 2- to 3-day-old animals, however, an aKe rise by about 1 mM and disturbance of rhythm occurred after a delay of 50 min. Glucose-free saline resulted, after about 30 min, in reversible blockade of respiratory rhythm and an aKe rise by more than 8 mM, whereas pHe remained unaffected. Exposure to anoxia for 30 min after 1 h of pre-incubation in 10 mM glucose led to a progressive rise of aKe, and a fall of [Ca]e. The concomitant suppression of rhythm was irreversible in preparations from 2- to 3-day-old animals. Similar effects on aKe and [Ca]e and irreversible blockade of rhythm were revealed during anoxia in glucose-free solution, or by addition of 2-5 mM iodoacetate to oxygenated or hypoxic solutions. Iodoacetate led to a slow increase of pHe by more than 0.2 pH units, which was accelerated by anoxia. Our findings show that normal respiratory network functions in the en bloc medulla, in particular from rats older than 1 day, depend on high bath glucose levels, necessary for effective utilization of anaerobic metabolism.     

Clinical significance of anaerobic bacteremias in a general hospital. A prospective study from 1988 to 1992

A prospective study was designed to investigate anaerobic bacteremias and evaluate their incidence and significance in a general hospital. One or more blood cultures positive for anaerobic microorganisms were analyzed from each of a total of 61 patients hospitalized between January 1988 and April 1992, in accordance with an established protocol. The clinical repercussions of bacteremia were also analyzed. Two percent of blood cultures were positive for anaerobes, with an incidence of 0.6 cases per 1000 hospitalized patients. The most frequently isolated anaerobes were Bacteroides fragilis and Clostridium perfringens. Intraabdominal disease was the route of entry in 50% of the patients. A death rate of 37.3% was mostly attributed to B. fragilis. Hospitalization in the surgical department, nosocomial acquisition, previous surgery, critical initial clinical status and the presence of complications were significantly associated with increased death rates. No significant differences were found in the clinical course between patients whose antibiotic treatment was judged adequate and those for whom it was considered inadequate. The frequency and incidence of anaerobic bacteremia was low in our hospital. The well-known clinical and epidemiological characteristics of these infections facilitates their prompt diagnosis and empirical treatment with antibiotics of proven effectiveness against anaerobes.     

Pulmonary Nocardia otitidiscaviarum infection in a patient with chronic respiratory infection

We report a case of pulmonary Nocardia (N.) otitidiscaviarum infection in a 76-year-old man with chronic respiratory infection. The patient responded poorly to intravenous imipenem and oral minocycline, but later improved after treatment with trimethoprim-sulfamethoxazole. Pulmonary infection with N. otitidiscaviarum should be considered in the differential diagnosis of chronic respiratory infections. Further studies are needed to evaluate the correlation between species and drug susceptibility.     

The noninfectious respiratory complications of infection with HIV

Infection with HIV was first recognized through a clustering of unusual respiratory infections. The lung has been a major target manifesting many of the infectious complications of the immunodeficiency. Noninfectious pulmonary complications in HIV-infected individuals are also common and have been recognized since the advent of the AIDS epidemic. Malignancies involving the respiratory system, specifically Kaposi's sarcoma and non-Hodgkin's lymphoma, are epidemiologically linked to infection with HIV. Although other cancers have been identified in patients with HIV, these malignancies have a relationship to HIV infection that is unknown. Nonetheless, all cancers in the HIV-infected individual appear to follow a very deadly course. Interstitial pneumonitis and an alveolitis are also seen in individuals infected with HIV. Their relationship to the virus is unknown but may involve the lung's immune response to HIV. Pneumothorax and bullous lung disease are the sequela of pulmonary infections in the HIV-infected host. Pulmonary hypertension has been reported in HIV-infected patients, and like the other noninfectious respiratory complications, the link between the disease process and HIV is unknown. Bronchiectasis is now commonly recognized in AIDS patients who have survived prolonged immunosuppression and infection. Bronchoscopists have accumulated a collection of endobronchial lesions uncommonly seen in non-HIV-related pulmonary consultation. In the following review, we discuss the epidemiology, pathology, pathogenesis, clinical features, diagnostic findings, prognosis, and therapeutic options available for each noninfectious pulmonary complication. As the life expectancy for HIV-infected patients increases, the incidence of noninfectious pulmonary complications will rise.     

Study of pathogenetic mechanisms of intoxication in patients with anaerobic non-clostridial infection

Pyoinflammatory diseases continue to be one of the most topical problem of modern medicine. Anaerobic non-clostridial infection is essential in the etiological pattern of pyoinflammatory diseases. Its specific feature is early developed severe intoxication. The authors have developed laboratory criteria for evaluating the degree of intoxication in patients with anaerobic non-clostridial infection, which are based on chromatographic determination of the concentrations of specific metabolic products, such as volatile fatty acids and toxic metabolites of the phenol group, in the patients' peripheral blood, which allows the detected disorders to be promptly corrected. The metabolic products of non spore-forming anaerobes, such as volatile fatty acids, are important pathogenetic factors since they inhibit the dynamic activity of platelets and the phagocytic activity of leukocytes in blood.     

Bovine respiratory syncytial virus protects cotton rats against human respiratory syncytial virus infection

Human respiratory syncytial virus (HRSV) is the most frequent cause of severe respiratory infections in infancy. No vaccine against this virus has yet been protective, and antiviral drugs have been of limited utility. Using the cotton rat model of HRSV infection, we examined bovine respiratory syncytial virus (BRSV), a cause of acute respiratory disease in young cattle, as a possible vaccine candidate to protect children against HRSV infection. Cotton rats were primed intranasally with graded doses of BRSV/375 or HRSV/Long or were left unprimed. Three weeks later, they were challenged intranasally with either BRSV/375, HRSV/Long (subgroup A), or HRSV/18537 (subgroup B). At intervals postchallenge, animals were sacrificed for virus titration and histologic evaluation. Serum neutralizing antibody titers were determined at the time of viral challenge. BRSV/375 replicated to low titers in nasal tissues and lungs. Priming with 10(5) PFU of BRSV/375 effected a 500- to 1,000-fold reduction in peak nasal HRSV titer and a greater than 1,000-fold reduction in peak pulmonary HRSV titer upon challenge with HRSV/Long or HRSV/18537. In contrast to priming with HRSV, priming with BRSV did not induce substantial levels of neutralizing antibody against HRSV and was associated with a delayed onset of clearance of HRSV upon challenge. Priming with BRSV/375 caused mild nasal and pulmonary pathology and did not cause exacerbation of disease upon challenge with HRSV/Long. Our findings suggest that BRSV may be a potential vaccine against HRSV and a useful tool for studying the mechanisms of immunity to HRSV.     

Reversible airflow limitation in adults with respiratory infection

The aim of the study was to determine the occurrence of airflow limitation and the frequency of significant reversibility in respiratory infections in adults without known asthma or chronic obstructive pulmonary disease (COPD). We also wanted to study the association between airflow limitation and aetiological agents diagnosed by serological analyses. Spirometry was performed in 574 adult general practice patients with upper or lower respiratory tract infection, and follow-up measurement was obtained in 429 of them. In the latter group, we also obtained paired sera for analysis of anti-bodies against respiratory viruses, chlamydial and mycoplasmal agents. Median forced expiratory volume in one second (FEV1) in all patients included was 90% of predicted; significantly lower in patients with an established diagnosis of asthma or COPD, compared to those without, 77 and 91% predicted, respectively. Among the patients without known asthma or COPD there was a strong association between low FEV1 and the symptoms cough and dyspnoea. Both acute-phase and follow-up FEV1 was measured in 395 of the patients without known asthma or COPD, and a significant increase in median value from 92 to 96% was registered. A reversibility of FEV1 of > 15% was measured in 23% of the 395 patients, uninfluenced by anti-asthma treatment in the great majority. Patients with an established viral, mycoplasmal or chlamydial infection had a significantly lower FEV1 at entry and a greater reversibility, compared to those without such aetiological diagnosis. We conclude that reversible obstruction was particularly common in the patients diagnosed as having acute bronchitis, but that it was found in the patients patients diagnosed as having upper respiratory tract infection.(ABSTRACT TRUNCATED AT 250 WORDS)