Bacteremic hemophilus influenzae pneumonia in adults. A report of 24 cases and a review of the literature

The Epidemiology of Alcohol Abuse and Pneumonia

The association between alcohol abuse and pneumonia has been recognized for more than two centuries and represents an enormous health burden worldwide. The first published notation of alcohol as a clinical risk factor for the development of pneumonia is now over 200 years old, and since then there have been over a 1,000 references in the medical literature confirming these observations. Even in this modern era of medicine pneumonia remains a common infection that afflicts over 450 million persons worldwide annually and causes 7 % of all deaths. When one considers that alcohol is the most commonly abused substance in the world, the enormous excessive burden that alcohol contributes to the morbidity and mortality of pneumonia represents a major public health consideration. In this chapter we review the foundational literature that has chronicled the evolution of our understanding of the association between pneumonia and alcohol abuse over the past century. In addition, we discuss some of the specific pathogens that are particularly associated with serious lung infections in individuals with alcohol use disorders. Finally, we consider some of the specific guidelines for the treatment and prevention of pneumonia in the setting of alcohol abuse.

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

Value of washed sputum gram stain smear and culture for management of lower respiratory tract infections in children

To date, the technique of washed sputum examinations has not been widely used in the clinical management of lower respiratory tract infections in children. A total of 224 sputum samples from 125 pediatric patients with lower respiratory tract infections were collected for washed sputum Gram stain smears and cultures. The results with these methods were compared to find correlation rates. The value of washed sputum cultures was assessed by examining the clinical responses of the patients who received antibiotic therapies instituted on the basis of the sputum culture results. Isolation rates of Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and Staphylococcus aureus were 22.4%, 9.4%, 4.9%, and 0.4%, respectively. For the prediction of H. influenzae, S. pneumoniae, and M. catarrhalis, the sensitivities of the washed sputum Gram stain smears compared with the culture method were 86.0%, 81.0%, and 90.9%, respectively. The specificities of the washed sputum Gram stain smear technique were 94.8%, 97.5%, and 98.1%, respectively. Overall, the sensitivity and specificity of the washed sputum Gram stain smear method were 85.5% and 87.2%, respectively. S. aureus was isolated from only one specimen; and washed sputum Gram stain smear estimation was correlated with the culture result. On the basis of the washed sputum culture results, appropriate antibiotic therapies were instituted for 93.3% of the patients with acute lower respiratory tract infections. This study suggests that the techniques of washed sputum Gram stain smear and culture are valuable and should be encouraged in clinical practice for the management of lower respiratory tract infections in children.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."

[Community-acquired pneumonia (CAP) with hospital treatment. The value of the clinical picture and complementary exams in predicting its etiology]

We studied 162 patients with community-acquired pneumonia admitted for hospital treatment, in order to determine the utility of clinical and ancillary examinations for predicting etiology and guiding the most appropriate empirical treatment. Acute first appearance of symptoms, purulent expectoration, chest sounds indicating lung condensation, pleuritic chest pain and leukocytosis over 12,500/ml were statistically significant in differentiating typical pneumonias from those with atypical behavior patterns. The last two features were the most relevant according to multivariate analysis. We conclude that careful taking of case histories and basic blood testing continue to be relevant and must not be considered anachronistic for the differential diagnosis of community-acquired pneumonias.

Haemophilus influenzae sepsis resulting from pneumonia

Haemophilus influenzae is a pleomorphic gram-negative bacterium that causes a myriad of infections in both adults and children. The organism frequently causes respiratory infections in patients with obstructive lung disease but may on occasion cause invasive infections including pneumonia with bacteremia. We report the case of a patient with underlying lung disease and metastatic malignancy in whom sepsis related to pneumonia caused by H. influenzae developed.

Bacterial pneumonia associated with HIV-1 infection

Bacterial pneumonia remains an important cause of treatable morbidity among HIV-1-infected persons. These pneumonias occur at all CD4 counts but are especially common as the HIV-1 infection progresses. Bronchopneumonia should be considered particularly in the setting of segmental or lobar consolidation associated with productive cough and fever. S. pneumoniae remains the most common pathogen causing bronchopneumonia. Because of the high rate of bacteremia, diagnosis may be facilitated by blood cultures. Treatment is similar to management of HIV-1-seronegative persons, although drug resistance against some bacteria may be an emerging problem. Several opportunities exist for prevention, and these should be pursued vigorously.

Respiratory infections: community-acquired pneumonia and newer microbes

Respiratory infections, especially community-acquired forms of pneumonia (CAP), are challenging for clinicians because (1) a causative microorganism can only be found in about 50% of cases; (2) initial therapy, therefore, must be based on a probable or most likely etiology in the context of the patient's overall medical condition; and (3) new microbes or those considered previously as normal flora or less virulent forms seem responsible for some cases. It is important to be acquainted with new causes of infection which include Legionella species, Chlamydia pneumoniae, diphtheroids in certain instances (Corynebacterium pseudodiphtheriticum), and viruses such as the Hanta strains. Infections with Bordetella pertussis are increasing. However, the ever present and most common cause of CAP, Streptococcus pneumoniae, continues to present problems because of increasing antibiotic resistance, the high case fatality rate when bacteremia accompanies pneumonia, and the inability to give prophylactic immunization to all people with risk factors for this infection.

Pneumonia in the elderly. Special diagnostic and therapeutic considerations

Clinical and radiologic signs and symptoms of gram-negative infections are often muted or obscured by a concurrent disease, and therefore, are not reliable for predicting the infecting organisms. Thus, initial therapy is nearly always empiric and based on the clinician's judgment that a patient's pneumonia is likely to be caused by particular pathogens. The choice of an appropriate regimen requires careful consideration of the extent and severity of coexisting illness and debilitation, the severity of the pneumonia, and the level of care required.

Prospective epidemiological study of invasive Haemophilus influenzae disease in adults

The incidence and characteristics of invasive Haemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence of Haemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23%) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70%) patients. Nontypeable Haemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34% of nontypeable strains were ampicillin resistant (p = 0.08). Multiple antibiotic resistance was also high among type b (53%) and nontypeable (18%) strains. The mortality rate was significantly higher in patients with pneumonia, bacteremia from an unidentified focus or shock at presentation.

Pneumonia due to Haemophilus influenzae among mechanically ventilated patients. Incidence, outcome, and risk factors

Incidence and potential risk factors for pneumonia due to Haemophilus influenzae in adults treated with mechanical ventilation in a medical-surgical ICU were investigated. Diagnosis was established in 91 episodes and H influenzae was isolated in 20 of them. Mean onset of ventilator-associated pneumonia (VAP) due to H influenzae was 10.8 days after intubation. Six patients with H influenzae VAP died in the ICU. Of 13 risk factors for developing VAP due to H influenzae, an absence of prior antibiotic treatment was the only variable which had statistical significance (p < 0.001). In these mechanically ventilated patients, Haemophilus influenzae was a common causative agent for VAP, frequently associated with Gram-positive cocci. Episodes of H influenzae VAP were associated with a lower mortality compared with other etiologies. The epidemiologic and clinical findings indicate that patients without a prior antimicrobial treatment have increased susceptibility to infections of the airway by H influenzae.

Pneumonia and chronic obstructive pulmonary disease. What special considerations does this combination require?

Patients with chronic obstructive pulmonary disease are at increased risk for both community- and hospital-acquired pneumonia, most often through aspiration. Community-acquired pneumonia often manifests with acute onset of chills, fever, cough, and pleuritic chest pain. Atypical pneumonia syndromes are characterized by subacute onset over several days and constitutional complaints. Hospital-acquired pneumonia may be contracted during altered consciousness or after intubation, ventilation, or exposure to pathogens. Knowledge of the disease process and the means to accurately diagnose these infections allows physicians to prescribe effective antibiotic therapy. Stable patients may receive oral therapy, but with severe or hospital-acquired pneumonia, parenteral therapy is required. Combinations of agents may be needed to cover the variety of pathogens that may be present.

Mode of presentation and diagnosis of bacterial pneumonia in human immunodeficiency virus-infected patients

Bacterial pneumonia (BP) has recently been reported to be more frequent in human immunodeficiency virus (HIV)-infected patients than in normal hosts. This study reviews the clinical and radiologic manifestations of BP in 132 consecutive pulmonary episodes over a 15-month period. BP was defined on a clinical basis as a pulmonary infiltrate accompanied by fever and improving in a few days with conventional antibiotics (trimethoprim-sulfamethoxazole excluded). In patients undergoing bronchoscopy (97 procedures), semiquantitative cultures and cell differentials of bronchoalveolar lavage (BAL) were performed, in addition to conventional staining and cultures for opportunistic infections. BP were frequent (45%), and the usual community-acquired pathogens were found. The radiologic manifestations of BP were often unusual, however, and 47% were indistinguishable from the typical appearance of Pneumocystis carinii pneumonia. BAL cultures had a sensitivity of 83 or 23%, depending on whether antibiotics were administered before bronchoscopy, using a cutoff value of greater than or equal to 10(4) bacteria/ml. The specificity of BAL culture was of 80.5% if patients with P. carinii pneumonia were taken as a control group. We conclude that BP is frequently encountered in HIV-infected patients. The clinical and radiologic presentation of BP may be indistinguishable from that of opportunistic infections. Semiquantitative cultures of BAL appear a valuable diagnostic tool to avoid unnecessary invasive diagnostic procedures or treatments.

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.

Pulmonary persistence of Haemophilus somnus in the presence of specific antibody

Chronic experimental Haemophilus somnus pneumonia was produced in five 8- to 12-week-old calves to investigate host-parasite relationships in the respiratory tract. Calves were depressed and pyrexic and coughed intermittently for 3 days and then recovered except for sporadic coughing. Bacteria persisted in the lung for 6 to 10 weeks or more. Immunoglobulin G1 (IgG1), IgG2, and IgM but no IgA antibodies specific for H. somnus were detected in serum. Bronchoalveolar lavage samples contained detectable IgG1, IgG2, IgM, and IgA antibodies specific for H. somnus throughout most of the experiment. The kinetics of the isotypic antibody response against H. somnus in serum and bronchoalveolar lavage fluids differed, suggesting that both local and systemic antibody responses had occurred. Persistence of pulmonary infection for 10 weeks or more in the presence of antibody may be due to an inappropriate distribution of isotypes, toxicity of H. somnus for bovine macrophages, and perhaps other factors. Three of the calves were challenged with a 10-fold-higher dose of H. somnus at 10 weeks after the original inoculation. Immunity against H. somnus was indicated by the rapid clearance of bacteria from the lungs and the presence of minimal pneumonia at necropsy 3 days after bacterial challenge.

Haemophilus influenzae pneumonia in young adults with AIDS, ARC, or risk of AIDS

PURPOSE

Since the acquired immunodeficiency syndrome (AIDS) was first described in 1981, we have observed an increasing number of cases of Haemophilus influenzae pneumonia, particularly in young adult patients. To confirm this observation, we systematically identified and reviewed all cases of H. influenzae pneumonia that occurred in adult patients recently hospitalized at our institution.

PATIENTS AND METHODS

Using a strict case definition, we identified all cases of adult H. influenzae pneumonia that were observed during a recent 32-month period at our institution, a large teaching hospital in New York City. We further reviewed each case record for evidence of AIDS, AIDS-related complex (ARC), or risk of AIDS.

RESULTS

H. influenzae pneumonia was diagnosed in 51 adults. Thirty-four cases occurred in young adults (mean age = 33.9 years) with AIDS risk factors, including 23 (67 percent) intravenous drug abusers, six (18 percent) homosexual men, and five (15 percent) with both risks. Nine patients (26 percent) had a previous or concurrent diagnosis of AIDS, four (12 percent) developed AIDS later, and 13 (38 percent) others had ARC. The common presenting symptoms in young adult patients with H. influenzae pneumonia were fever (100 percent), productive cough (100 percent), chest pain (53 percent), and dyspnea (47 percent). Lung consolidation was detected on physical examination in 20 (59 percent), and chest radiograph demonstrated unilateral infiltrates in 18 (53 percent) and bilateral infiltrates in 16 (47 percent), with pleural effusions in three (nine percent). Most patients had an elevated white blood cell count (mean = 9.6 X 10(9)/liter) with a left shift in 22 (65 percent), and hypoxia on room air (mean partial pressure of oxygen = 69 mm Hg). Four patients with H. influenzae pneumonia and coexisting Pneumocystis carinii pneumonia had diffuse, bilateral infiltrates on chest radiograph, with significantly more dyspnea and a higher serum lactate dehydrogenase level than the others. All but one patient showed improvement with appropriate therapy.

CONCLUSION

We conclude that potentially serious pneumonia caused by H. influenzae occurs in young adult patients with AIDS, ARC, or AIDS risk.

The role of percutaneous lung aspiration in the bacteriological diagnosis of pneumonia in adults

In a prospective study of 175 adults with acute pneumonia, percutaneous lung aspiration (PLA) was performed in 144 in an attempt to obtain a bacteriological diagnosis. Positive cultures were obtained from PLA in 90/144 cases (62.5%). The most common organisms isolated were Streptococcus pneumoniae (60%) gram-negative bacilli including Hemophilus influenzae (26%) and Staphylococcus aureus (11%). In 39% of those patients with positive PLA cultures, the same organism was isolated on blood cultures. Complications of PLA were uncommon, with hemoptysis in 4% and chest wall hematoma in 0.7% of patients. The incidence of post-aspirate pneumothorax was not determined in this study. PLA was found to be a safe and effective method of obtaining a bacteriological diagnosis in adult patients with pneumonia.

Comparison of amoxycillin/clavulanate with amoxycillin in children and adults with chronic obstructive pulmonary disease and infection with Haemophilus influenzae

71 children and adults (median age 7 years) with chronic obstructive pulmonary disease in which ampicillin-sensitive Haemophilus influenzae were isolated from lower airway secretions were included in a single-blind study comparing amoxycillin/clavulanate and amoxycillin alone. The dosage of amoxycillin was 50 mg/kg/day given together with probenecid and divided in 3 doses. Duration of treatment was 14 days. Clinical and bacteriological examinations were performed at study entry and again immediately after the treatment period. A late bacteriological follow-up 1.5 months after entry was performed. 65 patients were eligible for analysis of clinical outcome, and no difference between the groups was found. Side-effects were mild at a frequency of 3% for either preparation. In terms of eradication of the initially isolated H. influenzae amoxycillin/clavulanate tended to be better than amoxycillin, although the difference was not significant (70% and 57%, respectively). In a subset of 33 patients with polymicrobial flora amoxycillin/clavulanate was significantly more effective than amoxycillin. However, amoxycillin/clavulanate did not significantly reduce the emergency of beta-lactamase producing H. influenzae during treatment, and thus offers no advantage over amoxycillin in patients with amoxycillin-sensitive H. influenzae. The combination should be reserved to patients with either polymicrobial flora or ampicillin-resistant H. influenzae.

Haemophilus influenzae pneumonia in Melanesian adults: report of 15 cases

In a prospective study of 170 adult patients with acute pneumonia, Haemophilus influenzae was found to be the aetiological agent in 15 cases (8.8%). The diagnosis in all cases was based on positive cultures of blood or percutaneous lung aspirate, or both. Chronic lung disease was significantly more common in patients with H influenzae pneumonia than in patients with pneumonia due to other organisms but age, sex, and smoking history did not differ significantly. Lobar consolidation was the most common radiological pattern, being present in 10 of the 15 cases. Type b was the commonest serotype isolated, but three cases were due to non-typable (non-capsulate) strains. All patients survived, responding well to treatment with penicillin, ampicillin, or chloramphenicol. Haemophilus influenzae should be considered as a possible cause of pneumonia in adults, particularly those with underlying chronic lung disease.

Nonvalue of sputum culture in the management of lower respiratory tract infections

Establishment of the microbiological etiology of bacterial pneumonia by sputum culture is confounded by both lack of recovery of fastidious pathogens and contamination of specimens with oropharyngeal flora. We reviewed the clinical records from 249 patients over a 3-month period for evidence of pneumonia. Gram staining and cultures were performed on 381 specimens isolated from this population of patients. Recovery of respiratory tract pathogens was accomplished with 354 specimens from 226 patients; 27 specimens yielded normal flora in culture but were smear positive. An additional 256 specimens submitted to our microbiology laboratory did not meet smear criteria for purulence nor did they yield respiratory tract pathogens in culture. A total of 637 specimens submitted to the microbiology laboratory were evaluated for sputum purulence by the criteria of Bartlett. Of the total 354 specimens which were positive in culture for a pathogen, 182 (52%) were submitted from 150 patients with no objective evidence of pneumonia. The majority of specimens obtained from patients without pneumonia were nonpurulent. However, 71 of 182 culture-positive specimens obtained from 50 patients without pneumonia were purulent. Approximately half of these patients (31 of 50) had other pulmonary or upper respiratory tract pathology which could account for the sputum purulence. Among the 172 culture-positive specimens from 76 patients with pneumonia, only 100 (58%) were acceptable by smear criteria. An additional 23 patients provided expectorated purulent sputum from which no respiratory tract pathogen could be isolated. Of these 23, 7 had pneumonia. We conclude that sputum culture and Gram staining are neither specific nor sensitive as diagnostic tools. Objective criteria for purulence of Gram-stained specimens must be applied before their inoculation into culture media. Specimens should be sought only from patients with objective evidence of pneumonia.

Comparative evaluation of enoxacin, ofloxacin, ampicillin, and chloramphenicol for treatment of experimental Haemophilus influenzae pneumonia

A murine model of bacteremic Haemophilus influenzae type b pneumonia was used to evaluate the therapeutic efficacies of the quinolone antimicrobial agents enoxacin and ofloxacin compared with those of ampicillin and chloramphenicol. Ampicillin-susceptible (AS) and ampicillin-resistant (AR) challenge strains were employed. Treatment with enoxacin or ofloxacin produced intrapulmonary killing of H. influenzae that was superior to that achieved with ampicillin (P less than 0.01 to P less than 0.001 for both AS and AR strains). Ofloxacin and enoxacin also provided killing greater than that with chloramphenicol for the AS strain (P less than 0.01 to P less than 0.001). For the AR strain, ofloxacin provided killing greater than that obtained with chloramphenicol (P less than 0.001). Survival from AS strain pneumonia was 60% in enoxacin-treated and 78% in ofloxacin-treated animals compared with 41% for chloramphenicol-treated and 23% for ampicillin-treated groups. We conclude that enoxacin and ofloxacin may be effective antimicrobial agents in treating either AS or AR strains causing H. influenzae pneumonia.

Phlegmonous gastritis and Hemophilus influenzae peritonitis in a patient with alcoholic liver disease

A patient with alcoholic liver disease and ascites had Haemophilus influenzae peritonitis and died in spite of vigorous antibiotic therapy. At autopsy, a phlegmonous gastritis was found as a likely cause of the peritonitis. Phlegmonous gastritis is an uncommon cause of unexplained gastrointestinal symptoms in alcoholics and in the elderly, and it may be pathogenetic in rare patients with bacterial peritonitis of unclear source.

Pleural effusions caused by infection

Diagnostic thoracentesis is imperative when pneumonia is accompanied by an effusion (parapneumonic effusion). Examination of the pleural fluid is the only way to differentiate empyema and complicated parapneumonic effusions from uncomplicated parapneumonic effusions, and this differentiation is vital in deciding whether chest tube drainage is needed. If the aspirated pleural fluid contains pus or bacteria, closed chest tube drainage and antibiotic therapy should be started promptly. The same management approach is indicated if the pleural fluid pH is less than 7.00 or the glucose level is less than 40 mg/ml, since these effusions almost invariably are complicated parapneumonic effusions that do not resolve without fluid drainage. If the pleural fluid pH is greater than 7.20 and glucose level is more than 40 mg/ml, antibiotic therapy alone will suffice. Management of parapneumonic effusions with a pH of 7.00 to 7.20 should be based on serial observations of clinical status and pleural fluid findings.

Treatment of community-acquired pneumonias

Community-acquired pneumonia resulting in hospitalization may have a mortality rate of 10 to 25 percent. The exact incidence of community-acquired pneumonia is unknown because it is not a reportable disease. The etiologic spectrum appears to be changing. Streptococcus pneumoniae causes most of the cases; the rank ordering of other pathogens is uncertain. With the exception of Legionella, colonization of the upper respiratory tract usually precedes clinical pneumonia. Subtle aspiration of the posterior pharyngeal flora accounts for the majority of pneumonias. The need for prompt antibiotic therapy mandates an efficient approach to diagnosis, although it is often difficult to establish a precise etiology. Empiric therapy is often initiated prior to an etiologic diagnosis, and should be as specific as possible. Initial choice of therapy is dictated by the clinical presentation (e.g., "bacterial-like" or "viral-like"), inquiries into the possibility of aspiration or gram-negative pneumonia, and the results of gram-stain examination. When the clinical presentation and Gram-stain results are consistent with pneumococcal pneumonia, penicillin is the drug of choice. A more obtuse presentation in an otherwise healthy patient may call for erythromycin to cover Legionella and Mycoplasma. "Marginally compromised" hosts, such as alcoholics, patients with chronic obstructive pulmonary disease, and elderly nursing home patients, may require empiric broad-spectrum cephalosporin therapy for the first few days. Prevention of pneumonia using available vaccines must be emphasized.

Effect of systemic immunization on pulmonary clearance of Haemophilus influenzae type b

The effect of systemic immunization on pulmonary clearance of Haemophilus influenzae type b (Hib) was studied in a mouse model system. Immunization of mice by intraperitoneal injection of viable Hib cells resulted in the appearance of Hib-directed antibodies in both serum and bronchoalveolar lavage fluid. The development of this Hib-directed antibody activity was associated with significant enhancement of early pulmonary clearance of Hib. Systemic immunization did not affect the recruitment of polymorphonuclear leukocytes to the alveoli, suggesting that the enhanced clearance of Hib observed in immunized animals was due to specific antibodies which promote either phagocytosis or extracellular killing of Hib. The spectrum of Hib-directed antibody specificities detected in sera from immunized animals was essentially identical to that detected in bronchoalveolar lavage fluids from these same animals. Similarly, intravenous administration of an immunoglobulin G monoclonal antibody specific for Hib lipopolysaccharide resulted in the subsequent appearance of this antibody in the alveolar spaces where it enhanced pulmonary clearance of Hib. This study shows that this mouse model system can be used to measure the effect of both active and passive immunization on the clearance of Hib from the lower respiratory tract.

Antibody responses to capsular polysaccharide, lipopolysaccharide, and outer membrane in adults infected with Haemophilus influenzae type b

The antibody response to Haemophilus influenzae type b antigens as capsular polysaccharide, lipopolysaccharide, and outer membrane components was studied by enzyme-linked immunosorbent assay in 10 adults infected with this bacterium. Almost all patients had detectable amounts of immunoglobulins G and M antibodies specific to capsular polysaccharide, lipopolysaccharide, or outer membrane in their first serum sample. A significant antibody response in one or more antibody subclasses to capsular polysaccharide, lipopolysaccharide, and outer membrane was noted in 9 of 10, 7 of 10, and 7 of 10 patients, respectively. The occurrence of H. influenzae type b infections in adults cannot be completely explained either by the absence of antibodies against H. influenzae type b in their serum or by the failure to develop specific antibodies to the capsule or certain cell wall components even if these factors probably are important in some cases, e.g., in one patient who was splenectomized.

Pulmonary clearance of encapsulated and unencapsulated Haemophilus influenzae strains

A mouse model system was employed to investigate the temporal pattern of pulmonary clearance of Haemophilus influenzae and to evaluate the effect of the type b polysaccharide capsule on this clearance pattern. The lungs of BALB/c mice were inoculated with boluses of several different H. influenzae strains via an endobronchial catheter. A fully encapsulated H. influenzae type b strain multiplied readily in the lungs for at least 6 h and then was eventually cleared from the lungs over the next 18 h. The pulmonary clearance pattern obtained with an unencapsulated variant of this H. influenzae type b strain was identical to that obtained with the fully encapsulated parent strain. Two nontypable H. influenzae strains isolated by transtracheal aspiration of patients with acute H. influenzae pneumonia also multiplied in the lung and resisted significant clearance for at least 6 h after inoculation. Bolus deposition of either H. influenzae type b or nontypable H. influenzae in the lungs resulted in an eventual influx of polymorphonuclear leukocytes into the alveoli. The observed delay in clearance of all these strains suggests that resident host defense mechanisms must be augmented for clearance to occur. Furthermore, these data indicate that one or more factors other than the Haemophilus capsule are important bacterial determinants of pulmonary clearance of H. influenzae.

Immunoglobulin A from bronchopulmonary secretions blocks bactericidal and opsonizing effects of antibody to nontypable Haemophilus influenzae

Patients with chronic bronchitis are colonized by and may develop acute bronchopulmonary infection due to nontypable Haemophilus influenzae (NTHI) despite the presence of bactericidal and opsonizing antibody to the infecting organism. To test the hypothesis that secretory immunoglobulin A (IgA) interferes with host defense mechanisms, we extracted secretory IgA from bronchopulmonary secretions of five patients with NTHI pneumonia. NTHI was incubated with IgA before or during incubation with each patient's own serum or normal human serum. IgA from four of these individuals blocked the bactericidal and opsonizing effects of normal human serum and/or their own serum against their own and/or other NTHI. IgA from bronchopulmonary secretions of patients not infected with NTHI or from the serum of a patient with an IgA myeloma had no such effect. Blocking appeared to result from a direct interaction between IgA and the bacteria. The presumed mechanism is an interaction with bacterial surface antigens, although it is not known whether this occurs at antigenic sites responsible for bactericidal and opsonizing activity or whether interaction with adjacent antigenic sites and subsequent steric interference is responsible. This blocking effect of IgA may be one mechanism that allows for the development of NTHI colonization or pneumonia in an individual who already has seemingly adequate antibody against the infecting organism.

Incidence, predisposing factors and manifestations of invasive Haemophilus influenzae infections in adults

A retrospective study was conducted on invasive Haemophilus influenzae infections in adults (greater than or equal to 16 years) for the period 1971-1983 in two regions in Sweden. The annual incidence was determined to be 1.1 per 100,000. Predisposing factors included advanced age, bronchopulmonary diseases, alcoholism, traumatic head injury, malignant diseases and pregnancy. Pleuropulmonary infections were the most common manifestations followed by epiglottitis, meningitis and septicaemia of unknown origin. A death rate of 8% was established. Both encapsulated and non-typable strains were found to be potentially pathogenic, but the non-typable strains had a lower virulence.

Infections in the alcoholic

Serious infections appear to occur more frequently in alcoholic patients. However, whether this is due to the effects of alcohol per se or to the other frequent complications of alcoholism--nutritional deficiencies, cirrhosis, and poor hygiene--has not been determined. The host factors that may underlie an increased frequency of infection in alcoholics and the clinical infectious syndromes associated with alcoholism are described.

Empyema due to beta-lactamase-producing H. influenzae type b complicating severe laryngo-pharyngitis and cervical cellulitis

A 70-year-old woman presented to hospital with an acute life-threatening cervical cellulitis and laryngopharyngitis followed by pneumonia. Despite a month's treatment with intravenous antibiotics including cephamandole she developed a bacteremic empyema due to a beta-lactamase producing H. influenzae. Subsequent treatment with chloramphenicol and surgical drainage was curative. The same pathogen was later isolated from her grandson's throat. Chloramphenicol is recommended as the drug of choice in such cases.