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Query: UMLS:C0023241 (Legionella)
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The susceptibility of coliform bacteria and bacterial pathogens to free chlorine residuals was determined before and after incubation with amoebae and ciliate protozoa. Viability of bacteria was quantified to determine their resistance to free chlorine residuals when ingested by laboratory strains of Acanthamoeba castellanii and Tetrahymena pyriformis. Cocultures of bacteria and protozoa were incubated to facilitate ingestion of the bacteria and then were chlorinated, neutralized, and sonicated to release intracellular bacteria. Qualitative susceptibility of protozoan strains to free chlorine was also assessed. Protozoa were shown to survive and grow after exposure to levels of free chlorine residuals that killed free-living bacteria. Ingested coliforms Escherichia coli, Citrobacter freundii, Enterobacter agglomerans, Enterobacter cloacae, Klebsiella pneumoniae, and Klebsiella oxytoca and bacterial pathogens Salmonella typhimurium, Yersinia enterocolitica, Shigella sonnei, Legionella gormanii, and Campylobacter jejuni had increased resistance to free chlorine residuals. Bacteria could be cultured from within treated protozoans well after the time required for 99% inactivation of free-living cells. All bacterial pathogens were greater than 50-fold more resistant to free chlorine when ingested by T. pyriformis. Escherichia coli ingested by a Cyclidium sp., a ciliate isolated from a drinking water reservoir, were also shown to be more resistant to free chlorine. The mechanism that increased resistance appeared to be survival within protozoan cells. This study indicates that bacteria can survive ingestion by protozoa. This bacterium-protozoan association provides bacteria with increased resistance to free chlorine residuals which can lead to persistence of bacteria in chlorine-treated water. We propose that resistance to digestion by predatory protozoa was an evolutionary precursor of pathogenicity in bacteria and that today it is a mechanism for survival of fastidious bacteria in dilute and inhospitable aquatic environments.
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PMID:Survival of coliforms and bacterial pathogens within protozoa during chlorination. 322 66

Hospital acquired infections (HAI) represent one of the major problems, due to their elevated frequency and high number of fatal cases, in the control of infectious diseases. With the perspective to evaluate the incidence of bronchopulmonary infections and to determine their role as cause of death of hospitalized patients, as well as to identify the etiology and the associated risk factors, we have studied 105 autopsy cases of patients decreased in hospital. 37 patients had pneumonias, of which 48.6% were of hospital origin. Hospital pneumonia was responsible for death in 12.3% of the cases. The risk factors significantly associated with HAI were recognized to be the following: hospital recovery for a period longer than 10 days, and surgery. Among the etiologic agents isolated in HAI, there was a distinct prevalence in Gram-negative bacteria (55.5% of the samples), such as Pseudomonas aeruginosa, Klebsiella pneumoniae, Legionella pneumophila.
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PMID:[Epidemiology of bronchopulmonary hospital infections]. 324 60

Pneumonia from bacterial and viral agents is the fourth leading cause of death in persons over age 65, accounting for 169.7 deaths per 100,000 persons per year. This high incidence of infection is the result of aging itself as well as age-related coexisting illnesses and their therapies. These factors combine to affect upper and lower respiratory tract host defenses adversely against invading pathogens. Gram-negative colonization of the oropharynx, followed by the spread of bacteria to the tracheobronchial tree, commonly precedes the development of pneumonia. Bacterial adherence is one important and modifiable pathogenetic factor that leads to colonization at both of these sites. Diagnosis of pneumonia in the elderly is often thwarted by difficulties in recognizing infection, as signs and symptoms differ from those observed in younger patients. Therapy is confounded by the frequent inability to obtain adequate culture material to establish a likely pathogen and by altered drug metabolism. In this instance epidemiologic data may be helpful in guiding therapy. Streptococcus pneumoniae is the most common pathogen in community patients, followed by Legionella pneumophila and enteric gram-negative bacilli. Hospitalized and institutionalized individuals are commonly infected with Klebsiella pneumoniae and other enteric gram-negative bacilli, and Legionella pneumophila and Streptococcus pneumoniae are also found. Because recognition of pneumonia may be difficult and therapy is fraught with problems, mortality is high in the elderly. Accordingly, serious attention must be paid to prevention. Prophylaxis includes the use of pneumococcal and influenza vaccines as well as careful attention to the patient's host defense status. Disease states leading to impairment of the immune system should be sought, and efforts should be made to improve host factors that assist the individual in removing invading pathogens.
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PMID:Pneumonia in the elderly. 351 64

Bacterial plasmids have become valuable markers for the comparison of strains of nosocomial gram-negative bacilli. The importance of plasmids in nosocomial infections is primarily due to their transferable antibiotic resistance genes (R plasmids), but other plasmid-mediated traits may eventually serve as potential markers. Stable cryptic plasmids have also served to relate outbreak strains, particularly nonfermenting strains of gram-negative bacteria. Klebsiella pneumoniae and Serratia marcescens have been the major plasmid-containing species in outbreaks involving single or multiple species. Outbreaks of single species with common plasmid patterns have included the Enterobacteriaceae, Pseudomonas aeruginosa, Pseudomonas cepacia, Ewingella americana, and Legionella pneumophila. Intrageneric spread of the same or similar R plasmids has nearly always occurred within the Enterobacteriaceae in large medical centers or Veterans Administration hospitals. High-risk nurseries and burn units have been conspicuous foci for R plasmid evolution. Hospital epidemiologists and clinical microbiologists will likely have an ever-increasing need to determine the plasmid content of gram-negative bacilli producing endemic and epidemic nosocomial infections.
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PMID:Plasmids as epidemiologic markers in nosocomial gram-negative bacilli: experience at a university and review of the literature. 353 13

Intracellular multiplication of virulent Legionella pneumophila serogroup 1 was inhibited by human monocyte-derived macrophages activated by a glycoprotein extract of Klebsiella pneumoniae, RU 41.740. Macrophage cultures were infected with L. pneumophila in the presence of immune antibodies on day 7 of culture. Extracellular bacteria were removed an hour after infection, and various concentrations of RU 41.740 or an antibiotic, erythromycin, were added. Intracellular multiplication in the presence of RU 41.740 was significantly slowed down compared with that of cultures without RU 41.740. The reduction was, however, significantly less than that effected by erythromycin, which was used as a positive control for inhibition of intracellular multiplication. Cultures incubated with RU 41.740 before infection also demonstrated a significant reduction in the intracellular multiplication of L. pneumophila. In addition, RU 41.740 increased superoxide anion production from human monocytes in suspension in the presence of L. pneumophila. These results show that direct nonspecific activation of macrophages by a bacterial glycoprotein inhibits the intracellular multiplication of L. pneumophila and may suggest a role for activated macrophages in host defense against intracellular pathogens.
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PMID:Direct activation of human monocyte-derived macrophages by a bacterial glycoprotein extract inhibits the intracellular multiplication of virulent Legionella pneumophila serogroup 1. 362

This pilot study assessed the efficacy, safety and tolerance of intravenously administered imipenem/cilastatin in the treatment of adults hospitalised with community acquired pneumonia. Thirteen patients were treated with 500 mg imipenem and 500 mg cilastatin eight hourly for a minimum of five days. Eleven patients (85%) had a clinical cure; (Legionella pneumophila was the pathogen in four, Streptococcus pneumoniae in one, Branhamella catarrhalis in one, no pathogen identified in five). One patient had a partial response (Staphylococcus aureus); and one patient was a treatment failure (Haemophilus influenzae and Klebsiella ozaenae). Clinical and laboratory side effects were mild, reversible and did not require treatment to be stopped. We conclude that the combination of imipenem and cilastatin was effective as a single agent in the treatment of the majority of these patients with hospital referred community acquired pneumonia.
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PMID:Treatment of pneumonia with imipenem/cilastatin. 385 75

The most important lower respiratory infection is pneumonia, the fourth leading cause of death. Most cases of bronchitis are of viral etiology and are not major problems. Empyema can present an important problem in management. Although the diagnosis of pneumonia is usually relatively straightforward, the specific etiologic diagnosis remains a major problem. Availability of empyema fluid or a positive blood culture result can be helpful in making the etiologic diagnosis, but these are unavailable in most patients. Screening of sputum Gram stains under 100 X magnification is very important; there should be fewer than 10 squamous epithelial cells, more than 25 polymorphonuclear leukocytes, or both per field of this size. The major causes of pneumonia are Streptococcus pneumoniae, Mycoplasma pneumoniae, anaerobic bacteria, Staphylococcus aureus, various gram-negative aerobic or facultative bacilli and Legionella. However, many other organisms are capable of causing pneumonia, even in the immunocompetent host. Further adding to the problem is the fact that a number of different organisms are manifesting increasing resistance to antimicrobial agents. Our study with ticarcillin plus clavulanic acid included seven patients with pneumonia, one with empyema, and one with purulent tracheobronchitis. Organisms recovered from pleural fluid, transtracheal aspiration and sputum or tracheostomy aspirate included multiple anaerobes, pneumococci, S. aureus, Hemophilus influenzae, Klebsiella pneumoniae, K. ozaenae, Pseudomonas aeruginosa, Acinetobacter, Enterobacter cloacae, Proteus mirabilis, beta-hemolytic streptococci, Neisseria meningitidis and Branhamella catarrhalis. Several of the organisms were ticarcillin resistant. Eight of the patients had cures and the other patient showed improvement. Only minor side-effects were encountered--Coombs' positivity (without hemolysis), eosinophilia, drug fever and one case of questionable neutropenia.
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PMID:Lower respiratory tract infection. 407 97

Patients who develop bacterial pneumonia in the community often require admission to acute-care hospitals. Knowledge of the incidence of pneumonia due to different pathogens that are brought into an institution from the community may play a role in determining the patterns of infecting organisms responsible for hospital-acquired pneumonia. For 1 year, we prospectively reviewed the records of patients admitted to our 1000-bed community hospital with community-acquired bacterial pneumonia (CABP). Patients had clinical signs and symptoms, positive radiologic findings, and pure cultures of potential pathogens from sputum, blood, pleural fluid, lung aspirate, lung biopsy, or transtracheal aspirate. Pneumonia due to Legionella pneumophila was diagnosed by serum indirect fluorescent antibody (IFA) titer greater than or equal to 1:256 and clinical signs and symptoms along with response to erythromycin. Of 204 patients with bacterial pneumonia, the following pathogens were implicated: Streptococcus pneumoniae, Haemophilus species, L. pneumophila, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, oral anaerobic bacteria, Psuedomonas aeruginosa, Serratia marcescens, and others. Most patients were more than 50 years of age and many had evidence of underlying pulmonary disease. The etiology of CABP may not be as predictable as in the past. Empiric antimicrobial therapy for CABP should include agents with activity against the pathogens prevalent in the community.
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PMID:Community-acquired bacterial pneumonia requiring admission to hospital. 634 27

Ninety patients with serious infections, including 61 with septicaemia, pneumonia, peritonitis or meningitis, were treated with ceftazidime. Of these patients, 85.6% were clinically cured (73.3%) or improved (12.2%) by the antibiotic. In this study, 57.7% had infections due to Escherichia coli (24.7%), Klebsiella sp. (14.5%) and Pseudomonas sp. (18.5%). Two children with cystic fibrosis and Pseudomonas pneumonia and an adult with Legionella pneumonia responded well to ceftazidime treatment. Seventy patients had fever before treatment and most of them became apyrexial in less than 2 to 3 days. Ceftazidime was given either intramuscularly (42 patients) or intravenously (48 patients), in a dose of 1 g tds in 71 patients or 2 g tds in severe infections in 11 patients, or reduced to suit the renal function (7 patients) or in paediatric doses (2 children). Blood ceftazidime levels were measured in eight patients with normal renal function. The average level one hour post dosing was 45.2 mg/l and the average trough level was 8.1 mg/l. Six patients were suffering from variable degrees of renal insufficiency (serum creatinine 149 to 668 mmol/l). Their average blood level 1 h post-dosing was 68.8 mg/l. In a patient with meningitis, the CSF level was 2.4 mg/l 2 h after a 1 g dose. These levels are several times the ceftazidime MIC values for most clinical bacterial isolates. Ceftazidime is a valuable and safe alternative to aminoglycoside therapy.
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PMID:Ceftazidime: a new approach in the treatment of moderate and severe infections. 635 15

Although erythromycin was introduced into clinical medicine more than 28 years ago, the indications for its use continue to expand. This antibiotic has emerged as appropriate therapy for Legionnaires' disease, chronic bacterial prostatitis caused by Escherichia coli, Klebsiella pneumoniae, and Proteus species, enteritis and colitis produced by Campylobacter fetus, and soft tissue and pleuropulmonary anaerobic infections in which Bacteroides fragilis plays no role. In combination with an aminoglycoside, erythromycin has proven to be effective for perioperative antibiotic prophylaxis in patients undergoing elective colon surgery. Additional therapeutic indications continue to be explored. The renewed interest in erythromycin has resulted in a closer examination of its potential for toxicity. New untoward events attributed to erythromycin administration have been described. This antibiotic has produced both reversible hearing loss and pseudomembranous colitis. Erythromycin also possesses the ability to inhibit the degradation of theophylline.
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PMID:Erythromycin. New indications and toxicities. 719 77


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