Respiratory infections

How does azithromycin (AZ) benefit patients with severe COPD or cystic fibrosis (CF)?

FA Manian MD, MPH, , , , , Leave a comment

AZ is a macrolide antibiotic which interferes with bacterial protein synthesis by binding to the 50S ribosomal subunit. It is often used to treat acute respiratory tract infections due to Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, as well as Mycoplasma, Chlamydia, and Legionella sp1. Although it has no in vitro activity against many aerobic gram-negative bacilli such as Pseudomonas aeruginosa, its chronic use has often been associated with a significant reduction in the frequency of disease exacerbations in patients with chronic bronchiectasis and colonization due to this organism, including patients with COPD or CF1-3.

Because P. aeruginosa is invariably macrolide-resistant, the beneficial effect of AZ in chronically infected or colonized patients must be due to factors other than its direct effect on bacterial replication.  Several mechanisms have been invoked including: 1. Inhibition of quorum-sensing dependent virulence factor and biofilm production 2.Blunting of host inflammatory response (eg, ↑IL-10, and ↓ IL-1ß, IL-6, IL-8, TNF-α, and ↓ chemotaxis); and 3. Enhanced antiviral response1.

The latter finding is quite unexpected but AZ appears to augment interferon response to rhinovirus in bronchial cells of COPD patients3.  With respiratory viruses (including rhinoviruses) causing 20-55% of all COPD exacerbations, perhaps this is another way AZ may help the host! Who would have thought!!

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References

  1. Vos R, Vanaudenaerde BM, Verleden SE, et al. Anti-inflammatory and immunomodulatory properties of azithromycin involved in treatment and prevention of chronic lung allograft rejection. Transplantation 2012;94:101-109.
  2. Cochrane review. Treatment with macrolide antibiotics for people with cystic fibrosis and chronic chest infection. Nov 14, 2012. http://www.cochrane.org/CD002203/CF_treatment-with-macrolide-antibiotics-for-people-with-cystic-fibrosis-and-chronic-chest-infection
  3. Menzel M, Akbarshahi H, Bjermer L, et al. Azithromycin induces anti-viral effects in cultured bronchial epithelial cells from COPD. Scientific Reports 2016; 6:28698. DOI:10.1038/srep 28698.

 

 

How does azithromycin (AZ) benefit patients with severe COPD or cystic fibrosis (CF)?

Routine screening of my patient suspected of having tuberculosis (TB) shows that he is HIV seropositive. Does HIV affect the clinical manifestation of TB?

FA Manian MD, MPH, , , , , Leave a comment

Patients with newly-diagnosed TB are ~20 times more likely to be coinfected with HIV than those without TB. Unfortunately, the diagnosis of TB in HIV-infected patients is often delayed in part related to its atypical presentation1.

In HIV-infected patients with high CD4 counts, clinical manifestations of TB are usually similar to those without HIV infection (eg, subacute fever, weight loss, cough) with CXR often showing upper lobe infiltrates and/or cavitations typically seen in reactivation TB.

Lower CD4 counts, however, are associated with atypical CXR findings, including pleural effusions, lower or middle lobe infiltrates, mediastinal adenopathy, and lack of cavitary lesions1,2.  A normal CXR has been reported in 21% of patients with CD4 <200 cells/μl (vs 5% in those with higher counts)2.

Advanced immune suppression in HIV infection is also associated with negative sputum smears for acid-fast bacilli, concurrent extra-pulmonary disease, and immune reconstitution symptoms after initiation of anti-TB therapy1.

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References

  1. Kwan CK, Ernst JD. HIV and tuberculosis: a deadly human syndemic. Clin Microbiol Rev 2011;24:351-376. https://cmr.asm.org/content/24/2/351
  2. Greenberg, SD, Frager D, Suster B, et al. Active pulmonary tuberculosis in patients with AIDS: spectrum of radiographic findings (including a normal appearance). Radiology 1994;193:115-9. https://pubs.rsna.org/doi/abs/10.1148/radiology.193.1.7916467
Routine screening of my patient suspected of having tuberculosis (TB) shows that he is HIV seropositive. Does HIV affect the clinical manifestation of TB?

My patient with significant dyspnea appears to have an acute exacerbation of his chronic obstructive pulmonary disease (AE-COPD). How often do AE-COPD and pulmonary embolism (PE) coexist?

FA Manian MD, MPH, , , , , , , , , , Leave a comment

Simultaneous presence of PE in patients with AE-COPD is not rare, particularly in those with unexplained AE-COPD.

A recent systematic review and meta-analysis reported a pooled PE prevalence of 16.1% (95% C.I. 8.3%-25.8%) in unexplained AE-COPD, with 68% of emboli found in the main pulmonary arteries, lobar arteries or inter-lobar arteries (i.e. not subsegmental); the pooled prevalence of deep venous thrombosis (DVT) was 10.5% (95% C.I. 4.3%-19.0%) 1. Pleuritic chest pain and signs of cardiac failure were associated with AE-COPD, while symptoms suggestive of a respiratory tract infection argued against PE.

It remains unclear, however, if the threshold for evaluation of venous thromboembolism (VTE) should necessarily differ between patients with explained vs unexplained AE-COPD.

In one small study, the prevalence of VTE in “unexplained” AE-COPD was significantly higher (25%) than “explained” AE-COPD (including cases with  tracheobronchitis, pneumonia, cardiac disorders, exposure to irritant inhalants, and lack of compliance with treatment), but the VTE prevalence for the latter group was still 8.4%2.  Serum D-dimer level and Wells criteria may help exclude VTE in this patient population.

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References

  1. Aleva FE, Voets LWLM, Simons SO, et al. Prevalence and localization of pulmonary embolism in unexplained acute exacerbations of COPD: A systematic review and meta-analysis. CHEST (2016), doi: 10.1016/j.chest.2016.07.034.
  2. Gunen H, Gulbas G, In E, Yetkin O, Hacievliyagil SS. Venous thromboemboli and exacerbations of COPD. Eur Respir J 2010;35:1243-1248.

 

Contributed by Jeff Greenwald, MD, Core Educator Faculty, Department of Medicine, Massachusetts General Hospital

My patient with significant dyspnea appears to have an acute exacerbation of his chronic obstructive pulmonary disease (AE-COPD). How often do AE-COPD and pulmonary embolism (PE) coexist?

What is the significance of Howell-Jolly bodies in the peripheral smear of my patient with a spleen who presents with pneumonia?

FA Manian MD, MPH, , , , , , , , , , , , , , , , , , , , Leave a comment

Howell-Jolly bodies (HJBs, Figure) are often indicative of asplenia (either post-splenectomy or congenital absence) or hyposplenism associated with a variety of conditions, including  sickle cell disease, autoimmune disorders, celiac disease, inflammatory bowel disease (particularly ulcerative colitis), HIV, cirrhosis, primary pulmonary hypertension, splenic irradiation, amyloidosis, sarcoidosis, bone marrow transplantation, and high-dose corticosteroid therapy1-4.

Patients with pneumonia and HJBs on peripheral smear may be hyposplenic and at risk of potentially serious infections, predominantly caused by encapsulated bacteria eg, Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis3.  Such patients should be immunized against these organisms, including sequential receipt of both conjugated and polysaccharide pneumococcal vaccines3,5.

HJBs are nuclear remnants in circulating mature red blood cells which are usually pitted by the spleen under normal physiological conditions. 

Final Fun Pearl:  Did you know that  HJBs were named after Henry Howell, an American physiologist who pioneered the use of heparin as an anti-coagulant and Justin Jolly, a French hematologist who was among the first to film mitotic activity in cells?

howelljollymgh

Figure. Howell-Jolly body in an RBC. Photo courtesy of Michael S. Abers, MD

Contributed by Katarzyna Orlewska, Medical Student, Warszawski Uniwersytet Medyczny, Poland

 

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References

  1. Di Sabatino, A, Carsetti R, Corazza G. Post-splenectomy and hyposplenic states. Lancet 2011;378:86–97. https://www.ncbi.nlm.nih.gov/pubmed/21474172
  2. Brousse, V, Buffet P, Rees D. The spleen and sickle cell disease: the sick(led) spleen. Br J Haematol 2014;166: 165–176. https://www.ncbi.nlm.nih.gov/pubmed/24862308
  3. Mathew H, Dittus C, Malek A, Negroiu A. Howell-Jolly bodies on peripheral smear leading to the diagnosis of congenital hyposplenism in a patient with septic shock. Clin Case Rep 2015;3:714-717. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4551333
  4. Ryan FP, Smart RC, Holdsworth CD, et al. Hyposplenism in inflammatory bowel disease 1978;19:50-55. https://www.ncbi.nlm.nih.gov/pubmed/624506
  5. Kuchar E, Miśkiewicz K , Karlikowska M. A review of guidance on immunization in persons with defective or deficient splenic function. Br J Haematol 2015; 171:683-94.  http://onlinelibrary.wiley.com/doi/10.1111/bjh.13660/full

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What is the significance of Howell-Jolly bodies in the peripheral smear of my patient with a spleen who presents with pneumonia?

How should patients with hospital-associated pneumonia (HAP) be empirically treated under the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society?

FA Manian MD, MPH, , , , , Leave a comment

Although empiric selection of antibiotics should be based on the local distribution of pathogens associated with HAP and their antimicrobial susceptibilities, routine coverage of Staphylococcus aureus (not necessarily methicillin-resistant S. aureus [MRSA]) and Pseudomonas aeruginosa or other gram-negative bacilli is recommended1.

In patients not at high risk of mortality (including ventilatory support and septic shock) or risk for MRSA (i.e.prior IV antibiotic use within 90 days, hospitalization in a unit where >20% of S. aureus isolates are MRSA or the prevalence of MRSA is unknown), piperacillin-tazobactam, cefepime, levofloxacin, imipenem or meropenem alone is suggested.

In patients not at high risk of mortality but with factors that increase the likelihood of MRSA, piperacillin-tazobactam, cefepime/ceftazidime, ciprofloxacin/levofloxacin, imipenem/meropenem, or aztreonam, plus vancomycin or linezolid should be considered.

In patients at high risk of mortality or receipt of IV antibiotics during the prior 90 days vancomycin or linezolid plus 2 of the following should be used: piperacillin-tazobactam, cefepime/ceftazidime, ciprofloxacin/levofloxacin, imipenem/meropenem, amikacin/gentamicin/tobramycin, or aztreonam are recommended (avoid double β-lactams).

In patients with structural lung disease increasing the risk of gram-negative infections (ie, bronchiectasis or cystic fibrosis), double anti-pseudomonal coverage is recommended.

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Reference

  1. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis, Advance Access published July 14, 2016.https://www.ncbi.nlm.nih.gov/pubmed/27418577  
How should patients with hospital-associated pneumonia (HAP) be empirically treated under the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society?

What are some of the major changes in the 2016 Infectious Diseases Society of America and the American Thoracic Society guidelines on pneumonia in hospitalized patients?

FA Manian MD, MPH, , , , , , , , , , Leave a comment

The most noticeable change is the elimination of the concept of health-care associated pneumonia (HCAP) altogether1. This action is in part related to the fact that many patients with HCAP were not at high risk for multi-drug resistant organisms (MDROs) , and that individual patient risk factors, not mere exposure to healthcare facilities, were better determinant of  the need for broader spectrum antimicrobials.

Other noteworthy points in the guidelines include:

  • Although hospital-associated pneumonia (HAP) is still defined as a pneumonia not incubating at the time of admission and occurring 48 hrs or more following hospitalization, it now only refers to non-VAP cases; VAP cases are considered a separate category.
  • Emphasis is placed on each hospital generating antibiograms to guide providers with respect to the optimal choice of antibiotics.
  • Despite lack of supportive evidence, the guidelines recommend obtaining respiratory samples for culture in patients with HAP.
  • Prior intravenous antibiotic use within 90 days is cited as the only consistent risk factor for MDROs, including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas sp.

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Reference

  1. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis 2016 ;63:e61-e111.  Advance Access published July 14, 2016. https://www.ncbi.nlm.nih.gov/pubmed/27418577
What are some of the major changes in the 2016 Infectious Diseases Society of America and the American Thoracic Society guidelines on pneumonia in hospitalized patients?

Is cefpodoxime an appropriate oral antibiotic substitute for ceftriaxone when treating patients with respiratory tract infections caused by penicillin-resistant Streptococcus pneumoniae (PRSP)?

FA Manian MD, MPH, , , , Leave a comment

Short answer: No!

Although cefpodoxime is also a 3rd generation cephalosporin, its invitro activity against PRSP is not comparable to that of ceftriaxone.  In a study of 21,605 strains of S. pneumoniae collected internationally, whereas 89.1% of PRSP isolates were susceptible to ceftriaxone, only 35% were susceptible to cefpodoxime (1).  Among isolates resistant to penicillin and erythromycin, the susceptibility to ceftriaxone was 86.9% compared to that of 22.7% for cefpodoxime.

This information is important since 32%, and 17.6% of all S. pneumoniae isolates tested in this study  were either penicillin-resistant or penicillin- and erythromycin-resistant, respectively.  

So, when it comes to the coverage of PRSP, there is no oral cephalosporin “equivalent” to ceftriaxone and that includes cefpodoxime.  In fact, the package insert of cefpodoxime states that cefpodoxime is active against S. pneumoniae “excluding penicillin-resistant strains” (2).

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References

  1. Pottumarthy S. Fritsche TR, Jones RN. Comparative activity of oral and parenteral cephalosporins tested against multidrug-resistant Streptococcus pneumonia: report from SENTRY Antimicrobial Surveillance Program (1997-2003). Diag Microbiol Infect Dis 2005;51:147-150. https://www.sciencedirect.com/science/article/pii/S0732889304002081    
  2. http://www.accessdata.fda.gov/drugsatfda_docs/label/2007/050674s014,050675s017lbl.pdf; accessed June 20, 2016.
Is cefpodoxime an appropriate oral antibiotic substitute for ceftriaxone when treating patients with respiratory tract infections caused by penicillin-resistant Streptococcus pneumoniae (PRSP)?

What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

FA Manian MD, MPH, , , , , , , , , , , , , , , , Leave a comment

In MRSA pneumonia, the sensitivity of nasal swab PCR may vary from as low as 24.2% to 88% (1-3). A 2018 meta-analysis found an overall sensitivity of 70.9% (community-acquired pneumonia/healthcare-associated pneumonia [HCAP] 85%, ventilator-associated pneumonia 40%) with overall negative predictive value of 96.5% (based on an overall MRSA pneumonia prevalence of 10%) (4). 

A single center  study involving  patients with possible HCAP and a low clinical pulmonary infection score (CPIS) — for whom antibiotics may not be necessary anyway (5)—suggested that discontinuation of empiric vancomycin in patients without an adequate respiratory culture and a negative nose and throat culture may be reasonable (6).

However, a prospective study of ICU patients concluded that “clinicians cannot reliably use the results of initial negative MRSA nasal swab results to withhold empirical MRSA coverage from patients who otherwise are at risk for MRSA infection” (3).

The previously cited 2018 meta-analysis study (4) cautions against use of MRSA screening in patients with structural lung disease (eg, cystic fibrosis or bronchiectasis) because colonization may be more frequent in the lower respiratory tract in these patients and screening tests may therefore be discordant (4).

Collectively, the available data suggest that it is reasonable to use a negative MRSA screen to help exclude pneumonia due to this pathogen in patients in whom MRSA infection is not highly suspected or those who are not severely ill.

 

References

  1. Rimawi RH, Ramsey KM, Shah KB, et al. Correlation between methicillin-resistant Staphylococcus aureus nasal sampling, and S. aureus pneumonia in the medical intensive care unit. Infect Control Hosp Epidemiol 2014;35:590-92. https://www.ncbi.nlm.nih.gov/pubmed/24709733
  2. Dangerfield B, Chung A, Webb B, et al. Predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swab PCR assay for MRSA pneumonia. Antimicrob Agents Chemother 2014;58:859-64. https://www.ncbi.nlm.nih.gov/pubmed/24277023
  3. Sarikonda KV, Micek ST, Doherty JA, et al. Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment. Crit Care Med 2010;38:1991-1995. https://www.ncbi.nlm.nih.gov/pubmed/20683260
  4. Parente DM Cunha CB Mylonakis E et al. The clinical utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening to rule out MRSA pneumonia: A diagnostic meta-analysis with antimicrobial stewardship implications. Clin Infect Dis 208;67:1-7.
  5. Napolitano LM. Use of severity scoring and stratification factors in clinical trials of hospital-acquired and ventilator-associated pneumonia. Clin Infect Dis 2010;51:S67-S80. https://www.ncbi.nlm.nih.gov/pubmed/20597675
  6. Boyce JM, Pop O-F, Abreu-Lanfranco O, et al. A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia. Antimicrob Agents Chemother 2013;57:1163-1168. http://aac.asm.org/content/57/3/1163.full.pdf
What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

Are neuraminidase inhibitors (NAIs) such as oseltamivir (Tamiflu) still effective for treatment of influenza in my hospitalized patient with greater than 48 hours of symptoms?

FA Manian MD, MPH, , Leave a comment

Although there are no randomized controlled studies, several observational studies support  the benefit of NAIs even when initiated after 48 h of onset of symptoms. 

Although the sooner NAIs are initiated the more likely the odds of a favorable impact on the course of influenza, the FDA approval of these drugs was based on analysis of data in relatively healthy ambulatory patients not those who are often sicker and require hospitalization. 

A retrospective study reported improvement in survival even when treatment was delayed for 4-5 days after symptom onset (1). Other studies have reported more rapid viral clearance and clinical benefit in severe infections even when antivirals were initiated after 48 h (2).  

Collectively , these data suggest that in the presence of ongoing symptoms and likely active viral replication, NAI treatment should be seriously considered in hospitalized patients who are likely to have more severe disease.

In fact, CDC recommends  “initiation of antiviral treatment as early as possible” in hospitalized patients with influenza, and asserts that “antiviral treatment might be effective in reducing morbidity and mortality in hospitalized patients even if treatment is not started until >48 hours after onset of illness” (3).  

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References

  1. Louie JK, Yang S, Acosta M, et al. Treatment with neuraminidase inhibitors for critically ill patients with influenza A (H1N1) pdm09. Clin Infect Dis 2012;44:1198-1204. https://www.ncbi.nlm.nih.gov/pubmed/22843781
  2. Lee N, Ison MG. “Late” treatment with neuraminidase inhibitors for severely ill patients with influenza: better late than never? Clin Infect Dis 2012;55:1205-8. https://www.ncbi.nlm.nih.gov/pubmed/22843780
  3. CDC. Antiviral agents for the treatment and chemoprophylaxis of influenza: recommendations of the Advisory Committee on Immunization Practices. MMWR 2011;60 (RR01):1-24.
Are neuraminidase inhibitors (NAIs) such as oseltamivir (Tamiflu) still effective for treatment of influenza in my hospitalized patient with greater than 48 hours of symptoms?

Is there a seasonal variation in the incidence of cardiovascular (CV) events or venous thromboembolism (VTE)?

FA Manian MD, MPH, , , , , , , , , , 1 Comment

Seasonal variation, primarily characterized by a winter peak, has been reported for acute CV events, such as acute myocardial infarction (AMI) and sudden death, aortic rupture or dissection, and ischemic or hemorrhagic stroke, and VTE (1). A meta-analysis involving patients with VTE, primarily with a diagnosis of pulmonary embolism, revealed a 20% absolute increase in the incidence of VTE during January (1).  

Potential physiological mechanisms for these observations include increased sympathetic activity, decreased loss of fluids and sodium, increase in LDL cholesterol, increase in serum fibrinogen levels and other coagulation markers and C-reactive protein, and lower vitamin D levels due to shorter daylight hours during winter months (1,2).  At least in the case of AMI in the U.S., the higher incidence in winter is not affected by climate (2).  

Respiratory virus infections as a cause of acute inflammation leading to  CV or VTE events is another intriguing explanation (3). Indeed, influenza vaccination has been associated with reduction in hospitalization for cardiac disease and stroke among the elderly (4) and, in patients with cardiovascular disease, a reduction in death due to combined cardiovascular disease events such as heart attacks and strokes (5).

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References

  1. Dentali F, Ageno W, Rancan E, et al. Seasonal and monthly variability in the incidence of venous thromboembolism. A systematic review and a meta-analysis of the literature. Thromb Haemost 2011;106:439-447. https://www.ncbi.nlm.nih.gov/pubmed/21725580
  2. Spencer FA, Goldberg RJ, Becker RC, et al. Seasonal distribution of acute myocardial infarction in the Second National Registry of Myocardial Infarction. J Am Coll Cardiol 1998;31:1226-33.h ttps://www.ncbi.nlm.nih.gov/pubmed/9581712
  3. Woodhouse PR, Khaw KT, Plummer M, et al. Seasonal variations of plasma fibrinogen and factor VII activity in the elderly: winter infections and death from cardiovascular disease. Lancet 1994;343:435-39.  https://www.ncbi.nlm.nih.gov/pubmed/7508540
  4. Nichol KL, Nordin J, Mulloly J, et al. Influenza vaccination and reduction in hospitalization for cardiac disease and stroke among the elderly. N Engl J Med 2003; 348:1322-1332. http://www.nejm.org/doi/full/10.1056/NEJMoa025028
  5. Clar C, Oseni Z, Flowers N, et al. Cochrane Database of Systematic Reviews 2015. DOI: 10.1002/14651858.CD005050.pub3h ttp://www.cochrane.org/CD005050/VASC_flu-vaccines-for-preventing-cardiovascular-disease  

 

 

 

 

Is there a seasonal variation in the incidence of cardiovascular (CV) events or venous thromboembolism (VTE)?