Respiratory Failure, Persistent Fever and CMV from BAL: True, True and Unrelated?

Rita Pechulis MD

Samuel Krachman DO

Temple University

A 40-year-old HIV positive female (CD4+ count of 60 cells/ml) presented to the  Emergency Room with signs and symptoms of community acquired pneumonia.  On hospital day 3, her respiratory status worsened requiring mechanical ventilation.  Bronchoscopy with bronchoalveolar lavage (BAL) was negative for Pneumocystis (PCP) and Cytomegalovirus (CMV).  On hospital day 20, a tracheostomy was preformed due to failure to wean from mechanical ventilation.  During her ICU stay she developed multiple nosocomial infections, including vancomycin-resistant enterococcus (VRE) bacteremia and extended-spectrum beta-lactamase (ESBL) producing Klebsiella ventilator associated pneumonia, which were successfully treated. 

On hospital day 42 the patient developed new fevers as high as 102ºF. Repeat blood, sputum and urine cultures were negative.  On hospital day 51, she remained febrile with negative cultures and the nursing staff noted blood-streaked sputum.  Three days later, she developed copious bloody sputum with increased oxygen requirements while on mechanical ventilation.  Repeat bronchoscopy was preformed emergently revealing a large clot partially adherent to the anterior tracheal wall approximately 2 cm above the carina.  The tracheal mucosa was noted to be erythematous and ulcerated with multiple areas oozing bright red blood.  Ulcerations extended into the right and left main stem bronchi. Bronchial washings were positive for CMV.  There was no culture evidence of bacterial or fungal infection, PCP was not present, and herpes virus cultures were negative.

Question 1

The best test for the detection of CMV from bronchial washings in this patient is

1. CMV Culture
2. Rapid shell vial assay
3. Antigenemia assay
4. Serology (IgG, IgM titers)
5. PCR probe

Answer to Question 1

2) Rapid shell vial assay

This patient had a positive result by CMV rapid shell vial assay. This assay can be used on clinical samples such as urine, blood, and bronchial washings.  The test is performed by centrifuging the sample to increase the absorption of the virus; cell monolayers are then exposed to monoclonal florescent antibodies specific for the antigen MIE p72.  Binding of antibodies is indicative of early CMV replication within the cells and results can often be obtained within 24 hours. 

The main limitation in the use of rapid shell vial assay is its lack of sensitivity.  Using CMV culture as the gold standard, the rapid shell vial assay has a sensitivity of 69%, and specificity of 96%.1 However, it is important to remember that the presence of CMV in a sample does not always imply active infection; the diagnosis of CMV infection must be made using a combination of clinical suspicion, physical exam and detection of virus.

CMV culture is rarely used in the determination of active infection.  CMV grows slowly and may take 1 to 6 weeks for cytopathic changes to be evident.   Also, CMV viremia does not confirm active infection as asymptomatic shedding can occur for months after primary infection. Due to these limitations culture is not often performed. However, CMV culture may be useful in determining resistance patterns.

 The antigenemia assay quantifies the number of leukocytes positive for pp65, a structural protein found in CMV.  Positive results are reported as the number of cells with staining per total number of cells counted. In a study of HIV positive patients with CMV disease the antigenemia assay had a sensitivity of 97% for primary disease and 77% for patients with relapse resulting in an overall sensitivity of 91% and a specificity of 73%.2 While a negative assay is useful in ruling out primary CMV disease, the test is not specific enough to determine active disease. 

The diagnosis of CMV infection by serology involves the detection of CMV-specific IgM antibodies as well as the observation of at least a fourfold increase in CMV-specific IgG titers in paired specimens obtained two to four weeks apart.  Limitations of this test include the time lapse of 2 to 4 weeks required for paired serum samples. In addition, IgM antibody can persist for several months making the diagnosis of acute infection difficult.  However, titers are useful in determining past infection or exposure to CMV and may aid in the management of prophylaxis for patient with positive IgG titers.

There are multiple molecular assays such as quantitative and qualitative PCR, hybrid capture assay and nucleic assay sequence-based amplification.  Quantitative and qualitative PCR allow detection of viral DNA in whole blood, leukocytes and plasma.  Qualitative detection is useful for diagnosis with reported sensitivity and specificity of 89% and 75% in AIDS patients.  Quantitative PCR is useful for monitoring disease as high levels of viral DNA have been found to correlate with clinical symptoms in AIDS patients.  The hybrid capture assay utilizes an RNA probe targeting 17 percent of the CMV genome, the sample is then exposed to antibodies to RNA:DNA hybrids.  This assay can be used on whole blood specimens.  Nucleic assay sequence-based amplification detects both immediate-early gene UL123 (IE1) and late gene expression (pp67) of CMV infection, allowing the amplification of un-spliced viral mRNA’s in a background of DNA.   This assay is also performed on whole blood samples.3

Question 2

All of the following regarding the clinical significance of CMV isolated from BAL in a patient with HIV are correct except

1. CMV isolated from BAL in HIV patients always indicates infection and should be treated
2. CMV isolated from BAL in HIV patients has prognostic significance.
3. CMV is co-isolated with Pneumocystis jiroveci approximately 60% of the time
4. CMV isolated from BAL does not correlate with radiographic abnormalities or severity of gas exchange.
5. Routine treatment of CMV isolated from BAL is not recommended

Answer to Question 2

1) CMV isolated from BAL in HIV patients always indicated infection and should be treated.

Determining whether CMV is a pathogen or a bystander is clinically challenging.  CMV is commonly isolated from BAL of HIV patients. In one study, 9 of 19 asymptomatic HIV patients (47%) had CMV isolated from BAL.4 These patients were followed for 3 months and none developed respiratory symptoms.  CMV is also commonly isolated along with other pathogens such as Pneumocystis jiroveci.  In a study of 120 HIV patients with pulmonary symptoms who underwent BAL, 65 (54%) were positive for Pneumocystis jiroveci and of those 40 (61%) had concomitant CMV isolated.  The presence or absence of CMV had no effect on PaO2, A-a gradient or radiographic abnormalities as assessed by CXR.5  Another study  compared 57 patients with isolated Pneumocystis jiroveci versus 54 patients with Pneumocystis jiroveci and CMV present in BAL.  There were no significant difference in baseline characteristics, mortality or length of hospital stay between the two groups.6   Based on these studies, the routine treatment of CMV isolated from BAL in HIV patients is not recommended.

Even though treatment is often not indicated, isolation of CMV from BAL of HIV patients may have prognostic significance.  Hayner et al 7 analyzed 120 HIV patients with pulmonary symptoms.  Patients were divided into groups by the presence or absence of CMV in BAL.  They found that patients with CMV had significantly higher 3-month and 6-month mortality and the difference was not attributably to differences in CD4+ count or the presence or absence of Pneumocystis jiroveci.

Question 3

In autopsy studies of HIV patients, the three most common organs showing evidence of CMV infection include all of the following except

1. Lung
2. GI tract
3. Retina
4. Adrenal glands
5. Central Nervous System

Answer to Question 3

5) Central Nervous System

Patients dying of AIDS often have multiple coexisting infections.   As mentioned previously, documentation of clinically significant CMV infection is difficult.  Autopsy studies have been performed that provide some guidance in determining the spectrum of disease caused by CMV in AIDS patients.  Wallace et al evaluated autopsies of 54 patients with AIDS, 39 of whom were considered to have clinically significant CMV infection.8.  Evidence of infection was determined by the presence of intranuclear or intracytoplasmic inclusions with CMV cultured from autopsy tissue.  The lung was most frequently involved (80% of patients) and in 28% of patients, the lung was the only organ involved.  Of the patients with extra-pulmonary disease, 82% had more than one site of CMV infection.  The most frequent extra-pulmonary sites were the adrenals (72 %), the retina (41 %) and the GI tract (28%).  In two of the 31 patients with pulmonary disease, CMV was the only infectious agent identified.  One patient had CMV pneumonitis with concomitant ulcerative tracheobronchitis, similar to the patient described in this case.8   To our knowledge, this is the only other case of CMV associated ulcerative tracheobronchitis reported in the literature.

On hospital day 55 the patient was started on intravenous ganciclovir, and by day 60 the fever resolved.  Repeat bronchoscopy performed on day 64 revealed diffusely erythematous mucosa with no evidence of ulcerations or bleeding. 

Question 4

All of the following are true regarding ganciclovir except

1. Ganciclovir competitively inhibits the binding of dGTP to DNA polymerase inhibiting viral DNA synthesis
2. Concomitant use of imipenem/cilastatin may increase seizure potential
3. Stevens-Johnson syndrome occurs commonly with use of this product
4. Absolute neutrophil count <500/mm3 or platelets <25,000/mm3 are contraindications to use of ganciclovir due to the risk of worsening neutropenia/thrombocytopenia
5. Concomitant use of zidovudine may increase risk of leucopenia and thrombocytopenia and is not recommended

Answer to Question 4

3) Stevens-Johnson syndrome occurs commonly with use of this product

Ganciclovir is an antiviral agent that works by competitively inhibiting the binding of dGTP to DNA polymerase resulting in inhibition of viral DNA synthesis.  It is active against CMV and is indicated for treatment of CMV retinitis and prophylaxis in transplant patients.  The most common side effects are fever, rash, diarrhea, anemia leukopenia and thrombocytopenia.  Leukopenia and thrombocytopenia may be exacerbated by administration of zidovudine and should be avoided.  Other significant drug interactions include increased risk of seizure with concomitant use of imipenem/cilastatin.  Stevens-Johnson syndrome is uncommon with administration of ganciclovir, with reported incidence of <1%.9

The decision to treat CMV isolated from BAL in HIV patients is difficult. In our patient no other source of infection was found with cultures for bacteria, fungus, and herpes virus all negative.  There are cases where treatment of CMV may be beneficial.  Waxman et al 10 retrospectively reviewed the course of 9 AIDS patients with isolated CMV pneumonitis.  Five of the nine patients were treated with ganciclovir (5mg/kg q12 hr for 14 days). There were no differences in baseline characteristics between patients treated with ganciclovir and those not treated. At three-month follow up, all five of the treated patients were alive with complete resolution of pulmonary symptoms.  Of the four patients not treated, three died of respiratory failure and the remaining patient had persistent cough, dyspnea and wheezing and died one month later of a secondary infection.10

On hospital day 85 the patient was transferred to a ventilator-weaning unit and she was eventually liberated from mechanical ventilation.  The trachea was successfully decannulated on hospital day 121, and an airway inspection at that time noted a normal trachea with no evidence of stenosis. She was discharged on hospital day 151 after intensive physical therapy and will receive lifelong prophylaxis with ganciclovir.

References

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