Overwhelming pneumonia

Diagnosis and management of bacterial infections in decompensated cirrhosis

Bacterial infections are one of the most frequent complications in cirrhosis and result in high mortality rates. Patients with cirrhosis have altered and impaired immunity, which favours bacterial translocation. Episodes of infections are more frequent in patients with decompensated cirrhosis than those with compensated liver disease. The most common and life-threatening infection in cirrhosis is spontaneous bacterial peritonitis followed by urinary tract infections, pneumonia, endocarditis and skin and soft-tissue infections. Patients with decompensated cirrhosis have increased risk of developing sepsis, multiple organ failure and death. Risk factors associated with the development of infections are severe liver failure, variceal bleeding, low ascitic protein level and prior episodes of spontaneous bacterial peritonitis (SBP). The prognosis of these patients is closely related to a prompt and accurate diagnosis. An appropriate treatment decreases the mortality rates. Preventive strategies are the mainstay of the management of these patients. Empirical antibiotics should be started immediately following the diagnosis of SBP and the first-line antibiotic treatment is third-generation cephalosporins. However, the efficacy of currently recommended empirical antibiotic therapy is very low in nosocomial infections including SBP, compared to community-acquired episodes. This may be associated with the emergence of infections caused by Enterococcus faecium and extended-spectrum β-lactamase-producing Enterobacteriaceae, which are resistant to the first line antimicrobial agents used for treatment. The emergence of resistant bacteria, underlines the need to restrict the use of prophylactic antibiotics to patients with the greatest risk of infections. Nosocomial infections should be treated with wide spectrum antibiotics. Further studies of early diagnosis, prevention and treatment are needed to improve the outcomes in patients with decompensated cirrhosis.

Prevention and management of bacterial infections in cirrhosis

Patients with cirrhosis of liver are at risk of developing serious bacterial infections due to altered immune defenses. Despite the widespread use of broad spectrum antibiotics, bacterial infection is responsible for up to a quarter of the deaths of patients with liver disease. Cirrhotic patients with gastrointestinal bleed have a considerably higher incidence of bacterial infections particularly spontaneous bacterial peritonitis. High index of suspicion is required to identify infections at an early stage in the absence of classical signs and symptoms. Energetic use of antibacterial treatment and supportive care has decreased the morbidity and mortality over the years; however, use of antibiotics has to be judicious, as their indiscriminate use can lead to antibiotic resistance with potentially disastrous consequences. Preventive strategies are still in evolution and involve use of antibiotic prophylaxis in patients with gastrointestinal bleeding and spontaneous bacterial infections and selective decontamination of the gut and oropharynx.

Bacterial infections in cirrhosis

Spontaneous bacterial peritonitis, urinary tract infections, respiratory infections and bacteremia are the most frequent infective complications in cirrhosis. These infections are due to the concomitant presence of different facilitating mechanisms including changes in the intestinal flora and in the intestinal barrier, depression of activity of the reticuloendothelial system, decreased opsonic activity of the ascitic fluid, neutrophil leukocyte dysfunction and iatrogenic factors among others. The fact, that the probability of having a microorganism responsible for the infection quinolone resistant is higher than 30% should be taken into account when treating any infection in a cirrhotic patient receiving selective intestinal decontamination with quinolones, and therefore, quinolones as empiric treatment are not indicated.

Laboratory abnormalities in patients with bacterial pneumonia

STUDY OBJECTIVES

This study was undertaken to evaluate the laboratory abnormalities observed in patients with bacterial pneumonia as predictors of the severity of illness.

DESIGN

Retrospective analysis.

SETTING

Tertiary care hospital.

PATIENTS AND PARTICIPANTS

We studied 302 consecutive patients who were admitted to the Long Island Jewish Medical Center from January through December 1993 and treated for bacterial pneumonia. The patients were subdivided into two groups based on their serum phosphorus level either on hospital admission or 4 days before the onset of pneumonia, if this was acquired in-hospital. Hypophosphatemia (group 1) was defined as serum phosphorus level of < or = 2.4 mg/dL and normophosphatemia > 2.4 mg/dL (group 2). Three hundred randomly selected hospitalized patients treated for conditions other than pneumonia comprised the control group (group 3).

MEASUREMENTS

Groups 1 and 2 were compared with respect to laboratory data, mortality rate, and duration of hospitalization. The laboratory data of patients in group 3 were compared with those treated for bacterial pneumonia (groups 1 and 2). Stepwise multivariate logistic regression analysis was employed to identify the variables that best predicted the onset of pneumonia.

RESULTS

In groups 1 and 2, a greater (p < 0.0001) number of patients (135 of 302 patients with pneumonia, 44.7%) developed hypophosphatemia compared with patients in group 3 (31 of 300 control subjects, 10.3%). Patients with pneumonia (groups 1 and 2) had higher levels (p < 0.01) of bicarbonate compared with control subjects. Moreover, patients with pneumonia demonstrated lower levels (p < 0.01) of calcium, phosphorus, albumin, cholesterol, and alanine aminotransferase compared with control patients (group 3). Among patients with pneumonia, those with hypophosphatemia (group 1) had significantly lower levels (p < 0.05) of potassium, calcium, and albumin compared to those subjects with normophosphatemia (group 2). Furthermore, hypophosphatemic subjects manifested higher levels of glucose (p < 0.01) and creatine phosphokinase (p < 0.05) compared to their normophosphatemic counterparts. In addition, hypophosphatemic patients experienced a longer duration of hospital stay (hypophosphatemia, 24.6 +/- 2.0 days, vs normophosphatemia, 14.1 +/- 1.0, p < 0.001) and higher (p < 0.001) mortality compared to normophosphatemic subjects. The incidence of nosocomial pneumonia was higher (p < 0.0001) in hypophosphatemic patients compared to those with normophosphatemia.

CONCLUSION

We conclude that hypophosphatemia, hypocalcemia, hypokalemia, and hypoalbuminemia may be predictors of the severity of illness in patients admitted to the hospital with bacterial pneumonia.

A new diagnostic approach to the patient with severe pneumonia

36 patients with severe community-acquired pneumonia, treated in an intensive care unit (ICU), were examined in a prospective study using a comprehensive diagnostic program to establish an early etiological diagnosis. The resulting prompt and adequate antimicrobial therapy may have decreased the number of fatal cases. Special emphasis was placed on the use of a method incorporating fiberoptic bronchoscopy, together with protected brush sampling and bronchial lavage. An etiological diagnosis was established in 81% (29/36) of the cases. This etiological diagnosis was established within 48-72 h in 53% (19/36) of the patients, S. pneumoniae being the most frequent agent found (12 patients). This information, however, was poorly utilized since in only 11/19 of these patients was the antimicrobial therapy changed from a broad-spectrum antibiotic to a more specific narrow spectrum agent. The overall mortality rate was 22% (8/36). 7/8 patients who died had compromising factors. Most deaths in community-acquired pneumonia are still associated with pneumococcal infection. We conclude that fiberoptic bronchoscopy with brush samples via a plugged double lumen catheter provides the least misleading information concerning the etiological agent in pneumonia; sampling should be done as soon as possible after admission to the hospital, ideally before the need for ICU treatment; factors other than prompt antimicrobial therapy may influence the outcome of severe community-acquired pneumonia.

Treatment with aztreonam or tobramycin in critical care patients with nosocomial gram-negative pneumonia

During the course of one year, 47 critical care patients with gram-negative bacillary pneumonia at Millard Fillmore Hospital were randomly assigned to aztreonam or tobramycin therapy (two to one). Of these, 40 were fully evaluable for microbiologic and clinical response. All evaluable patients had gram-negative organisms in tracheal aspirate culture specimens and confirmed susceptibility of the organism to both study drugs. There was no difference between the two groups with respect to the percentage of patients who received concurrent antibiotics for gram-positive organisms. More than 60 percent of the patients received mechanical ventilation. Essentially, all had new lung infiltrates as shown by chest radiography, leukocytosis, recent onset of fever, and increased volume of purulent secretions. Half had multilobar pulmonary infiltrates. Their mean age was 73 years, with none under age 50. Most had chronic obstructive pulmonary disease, congestive heart failure, or both. By the prognostic nutritional index criteria, over 70 percent were nutritionally deficient at entry. The majority of infections were caused by Pseudomonas, Enterobacter, Klebsiella, and Escherichia coli. Aztreonam eradicated 92 percent of the causative gram-negative organisms, compared with 57 percent for tobramycin (p less than 0.05). Aztreonam produced a favorable clinical response (cure or improvement) in 93 percent of patients, compared with 50 percent for tobramycin (p less than 0.05). There were no differences in the minor adverse effects observed in the two treatment groups. Overall, aztreonam was superior to tobramycin for treatment of pneumonia due to susceptible gram-negative bacteria in these critical care patients.