Infectious diseases

My newly-admitted patient has positive blood cultures for Staphylococcus aureus.  How long should his S. aureus bacteremia be treated?

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

Because of the tendency of S. aureus bacteremia (SAB) to disseminate (eg, endocarditis, spinal epidural abscess, other metastatic infections), it should be treated with a minimum of 2 weeks of IV antibiotics following first repeat negative blood cultures, irrespective of the source of infection or rate of clinical improvement. 1-6

Beyond 2 weeks, the ultimate duration of parenteral antibiotics for treatment of SAB depends on several factors, including whether it is considered an “uncomplicated” or “complicated”. 1,2

Generally, uncomplicated SAB is defined as:

  • Negative results of follow-up blood culture at 2-4 days after bacteremia and
  • Clinical defervescence within 72 h of IV therapy and removal of the presumed focus of infection (eg, debridement of soft tissue infection or IV catheter) and
  • No evidence of metastatic infection among patients with catheter-related bloodstream infection or with primary bacteremia without evidence of endocarditis on transthoracic (TTE) or transesophageal echocardiogram (TEE) and
  • No endovascular foreign material (eg, prosthetic devices)

Patients not meeting the above criteria should be considered to have complicated SAB. Some studies have also reported primary bacteremia without obvious source and community-acquired SAB as risk factors for complications.4,6  

Even uncomplicated SAB should still receive at least 2 weeks of IV anti-staphylococcal therapy.  In a prospective observational study involving 111 patients with uncomplicated SAB, shorter course (<2 weeks) of IV antibiotic therapy was associated with significantly higher rate of relapse with a trend toward primary bacteremia associated with increased treatment failure.4

All other patients not considered to have an uncomplicated SAB, should receive extended antibiotic therapy (eg, 4-6 weeks or longer) depending on several factors, including clinical course and suspicion for a diagnosis of established metastatic disease (eg, endocarditis, spinal epidural abscess, etc…).  Continued parenteral antibiotic therapy is standard practice as there is insufficient data to support use of oral antibiotics in the treatment of complicated SAB before 4-6 weeks of therapy is completed.2

Standard practice in the treatment of SAB should also include an infectious disease (ID) consultation which has been associated with significantly reduced rates of mortality and risk of relapse.7

 Bonus Pearl: Did you know that SAB is associated with a mortality of 20-30% in developed countries despite antibacterial therapies and source control strategies? 1

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References

  1. Lam JC, Stokes W. The golden grapes of wrath—Staphylococcus aureus bacteremia: A clinical review. Am J Med 2023, 136:19-26. https://pubmed.ncbi.nlm.nih.gov/36179908/
  2. Kimming A, Hagel St, Weis S, et al. Management of Staphylococcus aureus bloodstream infections. Frontiers in Medicine 2021; 7: Article 616524. https://www.frontiersin.org/articles/10.3389/fmed.2020.616524/full
  3. Liu C, Bayer A, Cosgrove SE, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis 52:e18-e55. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/216060
  4. Chong YP, Moon SM, Bang KM, et al. Treatment duration for uncomplicated Staphylococcus aureus bacteremia to prevent relapse: Analysis of a prospective observational cohort study. Antimicrob Agents Chemother 2013;57:1150-56. https://pubmed.ncbi.nlm.nih.gov/23254436/
  5. Kuehl R, Morata L, Boeing C, et al. Defining persistent Staphylococcus aureus bacteremia: secondary analysis of a prospective cohort study. Lancet 2020;20: 1409-17. https://pubmed.ncbi.nlm.nih.gov/32763194/
  6. Fowler VG, Olsen MK, Corey R, et al. Clinical identifiers of complicated Staphylococcus aureus Arch Intern Med 2003;163:2066-72. https://pubmed.ncbi.nlm.nih.gov/14504120/
  7. Vogel M, Schmitz RPH, Hagel S, et al. Infectious disease consultation for Staphylococcus aureus bacteremia—A systematic review and meta-analysis. J Infect 2016, 72:19-28. https://pubmed.ncbi.nlm.nih.gov/26453841/ 

Disclosures/Disclaimers: 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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

My newly-admitted patient has positive blood cultures for Staphylococcus aureus.  How long should his S. aureus bacteremia be treated?

Is loss of sense of smell or taste much less common in Omicron-related Covid-19 compared to earlier strains of SARS-CoV-2?

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

Absolutely! Although loss of smell was a cardinal symptom of Covid-19 with earlier strains of SARS-CoV-2 (eg, Wuhan, alpha, delta), on average omicron causes olfactory dysfunction in only 13% of patients, 3-4 times lower than the earlier strains.1

But why is omicron less likely to causes loss of smell or taste? There may be at least 2 explanations. First explanation revolves around the solubility of omicron in the olfactory mucus. Recall that to access the olfactory epithelium, viruses and other pathogens have to first dissolve in and penetrate the mucus layer that not only allows odorants to reach the olfactory receptors but also protects the olfactory epithelium from toxins and pathogens. Hydrophilic and acid proteins can penetrate the mucus barrier more easily because they are more soluble in the mucus layer.1

What does this have to do with omicron? Well, it turns out that omicron with all its mutations in the spike protein is actually more alkaline than the Wuhan and delta strains. This means that omicron may have lower solubility in mucus and have a harder time reaching and infecting the olfactory epithelium. 1 Since the composition of olfactory mucous differs significantly from other mucus layers in the respiratory tract, omicron may still cause disease.2

Another potential mechanism may be related to the inefficiency of omicron in other steps necessary to infect nonneuronal cells of the olfactory epithelium within the nasal cavity, such as the endosomal route. 1 It turns out that cells of the olfactory epithelium express less of the endosomal membrane fusion proteases (cathepsins) which omicron prefers for cell entry! Fascinating! 

Bonus Pearl: Did you know that only 5-10% of functional olfactory neurons are required for a relatively normal sense of smell? This means that SARS-CoV-2 needs to eliminate at least 90% of all support cells of the olfactory neurons within a 3-4 day period (before their regeneration) for the host to notice anosmia?

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References

  1. Butowt R, Bilinska K, von Bartheld C. Why does the omicron variant largely spare olfactory function? Implications for the pathogenesis of anosmia in coronavirus disease 2019. J Infect Dis 2022;226:1304-1308. Why Does the Omicron Variant Largely Spare Olfactory Function? Implications for the Pathogenesis of Anosmia in Coronavirus Disease 2019 – PubMed (nih.gov)
  2. Yoshikawa K, Wang H, Jaen C, et al. The human olfactory cleft mucus proteome and its age-related changes. Sci Rep 2018;8:17170. The human olfactory cleft mucus proteome and its age-related changes – PMC (nih.gov)
  3. Harding JW, Getchell TV, Margolis FL. Degeneration of the primary olfactory pathway in mice. V. Long-term effect of intranasal ZNS04 irrigation on behavior, biochemistry and morphology. Brain Res 1978;140:271-85. Denervation of the primary olfactory pathway in mice. V. Long-term effect of intranasal ZnSO4 irrigation on behavior, biochemistry and morphology – PubMed (nih.gov)

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

Is loss of sense of smell or taste much less common in Omicron-related Covid-19 compared to earlier strains of SARS-CoV-2?

What’s the connection between flu vaccination and lower risk of Alzheimer’s Disease?

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

As far fetched that it may sound, there is growing evidence that flu vaccination is associated with lower risk of being diagnosed with Alzheimer’s Disease (AD).1

The most compelling evidence to date comes from a 2022 retrospective, propensity-matched study involving a nationwide sample of over 2 million U.S. adults ≥ 65 years old.1  This study found a 40% reduction in the risk of incident AD during the 4-year follow-up period when individuals receiving at least 1 dose of flu vaccine were compared to those who did not receive flu vaccination during the study period (number needed to treat-NTT 29.4). 

Despite its limitations, the results of the above study were concordant with those of several smaller studies that found an association between flu vaccination and lower risk of dementia of any cause.1-3  A 2022 meta-analysis also concluded that flu vaccination was associated with significantly lower risk (33%) of dementia among older people. Interestingly, in a study involving veterans, receipt of ≥6 doses of flu vaccines (not fewer) was associated with lower risk of dementia.4

Several hypotheses have been posited to explain the potential beneficial impact of flu vaccination on the risk of dementia, including: 1. Influenza-specific mechanisms, such as mitigation of damage secondary to influenza infection and/or epitopic similarity between influenza proteins and AD pathology; 2. Non-influenza-specific training of the innate immune system; and 3. Non-influenza-specific changes in adaptive immunity via lymphocyte-mediated cross-reactivity.1

So, in addition to its protective effect against severe influenza,5 and its association with lower risk of hospitalization for cardiac disease and stroke and reduction in death due to combined cardiovascular disease events (eg, heart attacks/strokes),  flu vaccination may be protective against AD! Who would have thought that a simple vaccine may have far reaching health benefits?

Bonus Pearl: Did you know that mice infected with non-neurotropic influenza strains have been found to have excessive microglial activation and subsequent alteration of neuronal morphology, particularly in the hippocampus, and that in APP/PS1 transgenic mice, peripheral influenza infection induces persistent elevations of amyloid- (A) plaque burden?1  Intriguing indeed!!!

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References

  1. Bukhbinder AS, Ling Y, Hasan O, et al. Risk of Alzheimer’s disease following influenza vaccination: A claims-based cohort study using propensity score matching. Journal of Alzheimer’s Disease 2022; 88:1061-1074. https://pubmed.ncbi.nlm.nih.gov/26945371/  
  2. Liu JC, Hsu YP, Kao PF, et al. Influenza vaccination reduces dementia risk in chronic kidney disease patients: A population-based cohort study. Medicine (Baltimore) 2016 95 :32868. https://pubmed.ncbi.nlm.nih.gov/26945371/
  3. Wiemken TL, Salas J, Hoft DF, et al. Dementia risk following influenza vaccination in a large veteran cohort. Vaccine 2021;39:5524-5531. https://pubmed.ncbi.nlm.nih.gov/34420785/
  4. Veronese N, Demurtas J, Smith L, et al. Influenza vaccination reduces dementia risk: A systematic review and meta-analysis. Ageing Res Rev 2022;73:101534. https://pubmed.ncbi.nlm.nih.gov/34861456/
  5. Godoy P, Romero A, Soldevila N, et al. Influenza vaccine effectiveness in reducing severe outcomes over six influenza seasons, a case-cae analysis, Spain, 2010/11 to 2015/16.  Euro Surveill 2018;23:1700732. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208006/
  6. Hosseini S, Michaelsen-Preusse K, Schughart K, et al. Long-term consequences of non-neurotropic H3N2 influenza A virus infection for the progression of Alzheimer’s Disease symptoms. Front. Cell. Neurosci 28 April 2021; https://doi.org/10.3389/fncel.2021.643650 https://www.frontiersin.org/articles/10.3389/fncel.2021.643650/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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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’s the connection between flu vaccination and lower risk of Alzheimer’s Disease?

How is Monkeypox different than Covid-19?

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

Just like Covid-19, Monkeypox (MP) is caused by a virus (this time related to smallpox), but there are major differences between these 2 diseases. 1-11

First, in contrast to Covid-19 which can easily be transmitted by casual contact through air, MP is primarily transmitted by close skin-to-skin contact (or possibly through contaminated clothing/bed linens) and sexual contact,  with great majority of current cases occurring among men who have sex with men (MSM); airborne transmission does not appear to be an important source of spread. 2

Although there is an overlap, the incubation period of MP tends to be longer (3-17 days) than that of Covid-19 which can be as few as 2 days.  Common to both diseases are flu-like symptoms such as fever, chills, muscle aches and headache, but MP is characterized by a rash that may be located on or near the genitals or anus or other areas, including hands, feet, chest face or mouth. 4

The rash (Figure) can look like pimples or blisters initially and may be painful or itchy as well. MP rash can either precede or follow flu-like symptoms after 1-4 days, or be the sole manifestation of the disease. Lymph node swelling or eye involvement (advise infected patients not to touch their eyes) may occur.  Although respiratory symptoms such as sore throat, nasal congestion and cough may occur with both diseases, shortness of breath would be unusual in MP.  A person with MP is considered contagious from onset of illness until the rash scabs over completely, which usually takes 2-4 weeks. 4,5,7,8

In contrast to Covid-19, currently there are no specific proven effective therapy against MP. However, several therapeutic agents with known activity against smallpox may be considered for those particularly at high risk of complications (eg, immunosuppressed patients, those with severe disease, exfoliative skin conditions [eg, eczema, psoriasis, Darier disease] children <8 years of age, pregnant or breast feeding patients, those with complications {eg, bacterial skin infection, pneumonia, gastroenteritis) or concurrent comorbidities.  These include an antiviral drug, Tecovirimat (TPOXX, ST-246) which can be obtained under an expanded-access protocol through the CDC in the U.S. (https://www.cdc.gov/poxvirus/monkeypox/clinicians/obtaining-tecovirimat.html. opens in new tab) — and Vaccinia Immune Globulin Intravenous (VIGIV) also through the CDC. 3,10

There are some “good news” related to MP when compared to Covid-19. First, in contrast Covid-19, hospitalization or death from MP due to the current circulating West African strain of the virus are extremely uncommon to rare.   In fact, of more than 12,000 cases of MP in 68 countries during the first few weeks of the epidemic, only 3 deaths have been reported, none in the U.S. thus far. 2

Second, in contrast to Covid-19, a person with MP is not considered infectious before onset of symptoms. So from a public health standpoint, it may be easier to control the spread of MP in the population following identification of a case. 9

Third, vaccination of contacts with one of the 2 available vaccinia/smallpox vaccines following significant exposure to MP may prevent disease altogether or render the disease milder. Vaccines should be administered within 4 days of exposure and no longer than 14 days after.  The generally preferred vaccine against MP is a modified vaccinia virus Ankara vaccine (MVA; JYNNEOS in the U.S., Imvanex in the European Union, and Imamune in Canada) which is live but non-replicative and is associated with fewer adverse events and contraindications than the alternative, ACAM2000, a live smallpox vaccine. 3

Last, in contrast to lack of pre-existing immunity to Covid-19 in virtually everyone  when the pandemic hit over 2 years ago, a large proportion of the population who received smallpox vaccine as part childhood vaccination (ending in 1972 in the U.S.) may have at least partial immunity against MP, resulting in either no or milder disease.6,11  

Bonus Pearl: Did you know that despite its name, monkeys are not a natural host of Monkeypox, with the causative virus having been isolated from a wild monkey in Africa only once? Instead, the virus first got its name after it was identified in a colony of Asian monkeys in a laboratory in Denmark in 1958. Squirrels, rats and shrew species serve as its natural host.1

Figure: Monkeypox rash (Courtesy CDC). 

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References

  1. Cohen J. Monkeypox is a new global threat. African scientists know what the world is up against. Science. June 1 2022. Monkeypox is a new global threat. African scientists know what the world is up against | Science | AAAS
  2. Osterholm MT. Gellin B. Confronting 21st-century monkeypox. Science 2022;377:349. Confronting 21st-century monkeypox | Science
  3. Medical countermeasures available for the treatment of monkeypox. Treatment Information for Healthcare Professionals | Monkeypox | Poxvirus | CDC. Accessed August 2, 2022.
  4. Key characteristics for identifying monkeypox. Clinical Recognition | Monkeypox | Poxvirus | CDC. Accessed August 6, 2022
  5. Monkeypox signs and symptoms. Signs and Symptoms | Monkeypox | Poxvirus | CDC. Accessed August 6, 2022.
  6. Karem KL, Reynold M, Hughes C, et al. Monkeypox-induced immunity and failure of childhood smallpox vaccine to provide complete protection. Clin Vaccine Immunol 2007;14:1318-27. Monkeypox-induced immunity and failure of childhood smallpox vaccination to provide complete protection – PubMed (nih.gov)
  7. Monkeypox: Key facts. Monkeypox (who.int). Accessed August 6, 2022.
  8. Clinical presentations of Covid-19. Clinical Presentation | Clinical Care Considerations | CDC. Accessed August 6, 2022.
  9. How monkeypox spreads. How it Spreads | Monkeypox | Poxvirus | CDC. Accessed August 6, 2022.
  10. Sherwat A, Brooks JT, Birnkrant D, et al. Tecovirimat and the treatment of monkeypox—past, present, and future. N Engl J Med 2020. August 3, 2022. Tecovirimat and the Treatment of Monkeypox — Past, Present, and Future Considerations | NEJM
  11. Mandavilli A. Who is protected against monkeypox. NY Times. May 26, 2022. Who Is Protected Against Monkeypox? – The New York Times (nytimes.com)

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

How is Monkeypox different than Covid-19?

Why do some patients with Covid-19 develop a rebound after completing a course of Paxlovid (nirmatrelvir/ritonavir) and how common is it?

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

Covid-19 rebound, characterized by the recurrence of Covid-19 symptom or a new positive viral test after having tested negative, is a poorly understood phenomenon that can occur after completion of therapy with Paxlovid, Molnupiravir (another antiviral Covid-19 drug) and even in patients with acute Covid-19 who never received any specific antiviral therapy. 1-6

Based on very limited number of studies, it appears that rebound is not caused by emergence of drug resistance or absence of neutralizing immunity, rather resumption of SARS-CoV-2 replication following completion of therapy, triggering a secondary immune-mediated response that’s associated with clinical symptoms.2,3

Recent studies suggest that rebound following Paxlovid treatment may not be as common as one may think.  In a cohort of 483 high-risk patients treated with Paxlovid for Covid-19, 0.8% experienced rebound of symptoms within 30 days of diagnosis, which were generally mild at a median of 9 days after treatment, all resolving without additional antiviral therapy.3  In this study, the median age was 63 years and 93% were fully vaccinated; there were no hospitalization related to rebound or deaths. In another study (pre-print) involving over 11,000 patients treated with Paxlovid, rebound symptoms occurred in 2.3% and 5.9% of patients  7 and 30 days following therapy, respectively, with similar rates reported in patients treated with Molnupiravir.4

Interestingly, a preprint article involving 568 untreated patients with mild-moderate Covid-19 found that 27% had symptom rebound after initial improvement with 12% having viral rebound based on nasal swabs with ≥0.5 log viral RNA copies/ml. 5 So antiviral therapy for Covid-19 is not a prerequisite for rebound symptoms.

Although some have suggested that insufficient drug exposure either due to individual pharmacokinetics or insufficient duration may be the cause of rebound in treated patients,2   there is currently no evidence that additional treatment for Covid-19 is needed in these patients.6

Despite reports of rebound, Paxlovid should still be considered in selected patients with mild-moderate Covid-19 at high risk of complications to minimize the risk of hospitalization and death from Covid-19. 

Bonus Pearl: Did you know that, according to CDC, Covid-19 rebound often occurs between 2-8 days following initial recovery? 1

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References

  1. Covid-19 rebound after paxlovid treatment. May 24, 2022. COVID-19 Rebound After Paxlovid Treatment (cdc.gov)
  2. Carlin AF, Clark AE, Chaillon A, et al. Virologic and immunologic characterization of Coronavirus Disease 2019 recrudescence after nirmatrelvir/ritonavir treatment. Clin Infec Dis 2022 (June 20). Virologic and Immunologic Characterization of Coronavirus Disease 2019 Recrudescence After Nirmatrelvir/Ritonavir Treatment | Clinical Infectious Diseases | Oxford Academic (oup.com)
  3. Ranaganath N, O’Horo JC, Challner DW, et al. Rebound phenomenon after nirmatrelvir/ritonavir treatment of Coronavirus Disease-2019 in high-risk persons. Clin Infect Dis 2022 (June 14). https://doi.org/10.1093/cid/ciac481 Rebound Phenomenon after Nirmatrelvir/Ritonavir Treatment of Coronavirus Disease-2019 in High-Risk Persons | Clinical Infectious Diseases | Oxford Academic (oup.com)
  4. Wang L, Berger NA, David PB, et al. Covid-19 rebound after Paxlovid and Molnupiravir during January-June 2022. MedRxiv 2022. COVID-19 rebound after Paxlovid and Molnupiravir during January-June 2022 | medRxiv
  5. Deo R, Choudhary MC, Moser C, et al. Viral and symptom rebound in untreated Covid-19 infection. Medrxiv 2022. Viral and Symptom Rebound in Untreated COVID-19 Infection (medrxiv.org)
  6. Covid-19 rebound after Paxlovid treatment. May 24, 2022. HAN Archive – 00467 | Health Alert Network (HAN) (cdc.gov)

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

 

 

Why do some patients with Covid-19 develop a rebound after completing a course of Paxlovid (nirmatrelvir/ritonavir) and how common is it?

What’s so “special” about SARS-CoV-2 Omicron subvariants BA.4 and BA.5?

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

BA.4 and BA.5 now account for the majority of Covid cases in the U.S.1  Several concerning features of BA.4 and BA.5 when compared to earlier strains of SARS-CoV-2 include:2-6

  1. High reproductive rate or R0 ie, the average number of new infections generated by an infectious person in a totally naïve population. BA.4/5 has an estimated R0 of 18.6, according to a one report.  For comparison, the R0 for the original Wuhan variant was estimated at 3.3, for Delta  5.1, early Omicron  9.5, BA.1 13.3, mumps 12, and measles 18.  So, it’s not surprising that we are currently experiencing higher rates of SARS-CoV-2 transmission in the population than just a few weeks ago.3
  2. Suboptimal existing immunity following prior infections due to Omicron variants BA.1 and BA.2, or prior vaccinations (including 3 doses of Pfizer vaccine).2,4
  3. More efficient spread than BA.2 when studied in human lung cells invitro. 2
  4. More pathogenic than BA.2 in hamsters. 2
  5. Reduced activity of SARS-CoV-2 therapeutic monoclonal antibodies.4
  6. Antigenically distant from other SARS-CoV-2 variants, with 50 mutations, including more than 30 on the spike protein, the viral protein targeted by Covid vaccines to induce immunity.5,6

Despite these potentially ominous traits, currently there is no evidence that  BA.4 or BA.5 is inherently more likely to cause severe disease than that caused by other Omicron subvariants.   The sheer number of infected persons in the population due to high transmission rates, however, will likely translate into higher hospitalization and deaths which has already happened in many areas.

High transmission rates also mean that we should not abandon the usual public health measures (eg, social distancing, masking indoors in public spaces) and vaccination with boosters for eligible persons with the aim of reducing hospitalization and death, if not infections.  

Bonus Pearl: Did you know that BA.4 and BA.5 became dominant in South Africa in April, 2022, despite 98% of the population reportedly having some antibodies from vaccination or previous infection or both?  

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References

  1. Leatherby L. What the BA.5 subvariant could mean for the United States. NY Times, July 7, 2022. https://theconversation.com/australia-is-heading-for-its-third-omicron-wave-heres-what-to-expect-from-ba-4-and-ba-5-185598
  2. Kimura I, Ymasoba D, Tamura T, et al. Virological characteristics of the novel SARS-CoV-2 Omicron variants including BA.2.12.1, BA.4 and BA.5. bioRxiv, preprint doi: https://doi.org/10.1101/2022.05.26.493539 , posted May 26, 2022. Accessed July, 13, 2022.
  3. Esterman D. The Conversation. Australia is heading for its third Omicron wave. Here’s what to expect from BA.4 and BA.5. July 4, 2022. https://theconversation.com/australia-is-heading-for-its-third-omicron-wave-heres-what-to-expect-from-ba-4-and-ba-5-185598
  4. Tuekprakhon A, Nutalai R, Dijokaite-Guraliuc A, et al. Antibody escape of SARS-COV-2 Omicron BA.4 and BA.5 from vaccine and BA.1 serum.
  5. Katella K. Omicron and BA.5: A guide to what we know. YaleMedicine, July 6, 2022. https://www.yalemedicine.org/news/5-things-to-know-omicron
  6. Topol E. The BA.5 story. The takeover by this Omicron sub-variant is not pretty. Ground Truths. June 27, 2022. https://erictopol.substack.com/p/the-ba5-story

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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’s so “special” about SARS-CoV-2 Omicron subvariants BA.4 and BA.5?

My elderly patient with UTI and E. coli bacteremia is ready to be switched from IV to oral antibiotic. Can I consider an oral beta-lactam in place of a fluoroquinolone or trimethoprim-sulfamethoxazole to complete an adequate course of antibiotic therapy at home.

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

Although oral fluoroquinolones (FQs) and trimethoprim-sulfamethoxazole (TMP-SMX) have been routinely recommended as step-down therapy for treatment of Enterobacterales bacteremia owing to their high bioavailability, increasing evidence suggests that beta-lactam (BL) antibiotics (particularly those with high bioavailability, such as cephalexin) are as effective without the attendant adverse risks associated with FQs—with increasing FDA warnings—and TMP-SMX.1,2

In the largest study to date involving a retrospective review of over 4,000 cases of Enterobacterales UTI-associated bacteremia (eg, E. coli, Proteus spp., Klebsiella spp) in Veterans Affairs hospitals, no significant difference in the main outcome (composite of 30-day all cause mortality or 30-day recurrent bacteremia) was found between the oral beta-lactam and FQ/TMP-SMX groups (4.4% vs 3.0%, respectively); additionally, when examined separately, no significant difference in mortality (3.0% vs 2.6%) or recurrent bacteremia (1.5% vs 0.4%) was found. 1

A meta-analysis of 8 retrospective studies (2019) also failed to find a significant difference in mortality or recurrent bacteremia between BLs and FQs or TMP-SMX groups; it did find a higher odds of any recurrent infection, however (5.5% vs 2.0% (O.R. 2.06, 1.18-3.61). 2

Before selecting an antibiotic, however, it’s important to recall that not all oral BLs are  created equal, with some having better bioavailability than others.   More specifically, it may not be common knowledge that cephalexin (“Keflex”), a commonly prescribed and inexpensive cephalosporin with great safety profile, has 90-100% bioavailability, rivaling those of FQs or TMP-SMX.

 Of interest, in a subset of patients who received cephalexin as step-down therapy (n=245) in the VA study above, the outcomes were nearly identical to those who received FQ or TMP-SMX, with a 30-d recurrent bacteremia of 0% and a 30-day mortality of 2% (vs 0.4% and 2.5% for ciprofloxacin and 1.0% and 2.4% for TMP-STX, respectively). Of note nearly one-half of the cephalexin group received a higher dose of 500 mg 4x/day, with the rest receiving less frequent dosing. 

These findings makes one wonder whether suboptimal oral BL dosing may not have contributed to the discrepant results from earlier studies suggesting the superiority of FQs or TMP-SMX over oral BLs as step-down therapy. 1,2

 

Bonus Pearl: Did you know that cephalexin may be given up to 4 gm/day in 4 divided doses with 90% of the drug excreted unchanged in the urine? 3

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References

  1. Sutton JD, Stevens VW, Chang NCN, Khader K, et al. Oral beta-lactam antibiotics vs fluoroquinolones or trimethoprim-sulfamethoxazole for definite treatment of Enterobacterales bacteremia from a urine source. JAMA Network Open 2020;3 (10):e20220166. Oral β-Lactam Antibiotics vs Fluoroquinolones or Trimethoprim-Sulfamethoxazole for Definitive Treatment of Enterobacterales Bacteremia From a Urine Source – PubMed (nih.gov)
  2. Punjabi C, Tien V, Meng L, et al. Oral fluoroquinolone or trimethoprim-sulfamethoxazole vs beta-lactams as step-down therapy for Enterobacteriaceae bacteremia: systematic review and meta-analysis. Open Forum Infect Dis 2019;6:ofz364 doi:10.1.1093/ofid/ofz364   https://pubmed.ncbi.nlm.nih.gov/31412127/
  3. Herman TF, Hasmi MF. Cephalexin. StatPearls (internet). https://www.ncbi.nlm.nih.gov/books/NBK549780/ Accessed July 10, 2022.

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

My elderly patient with UTI and E. coli bacteremia is ready to be switched from IV to oral antibiotic. Can I consider an oral beta-lactam in place of a fluoroquinolone or trimethoprim-sulfamethoxazole to complete an adequate course of antibiotic therapy at home.

My patient with COPD on prednisone with recurrent pneumonia has a low serum IgG level.  Can corticosteroids lower serum immunoglobulin levels?

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

Yes! Both exogenous and endogenous hypercortisolism may be associated with a drop in serum immunoglobulin levels, particularly IgG, which may persist even after discontinuation of steroid treatment.1-4 This means that a low serum IgG level in a patient on corticosteroids should be interpreted with caution and may not necessarily suggest primary antibody deficiency.

Although some early studies did not find a significant impact of corticosteroids on immunoglobulin levels, several subsequent studies found otherwise.  A 1978 study involving atopic asthmatic patients (averaging 16.8 mg prednisone daily) found that mean serum IgG significantly decreased (-22%) with milder drop in IgA levels (-10%) and no drop in serum IgM levels.2 Of interest, IgE level increased significantly initially but later dropped as well. More importantly, mean serum IgG levels remained significantly decreased an average of 22 days after corticosteroids were discontinued.

More recently, in a study involving patients with giant cell arteritis and polymyalgia rheumatica on corticosteroids, 58% developed antibody deficiency with the great majority involving IgG, either alone or along with other immunoglobulins.3 The reduction of IgG persisted even after discontinuation of corticosteroids in nearly 50% of patients, and observed in nearly one-quarter of patients for at least 6 months! Whether low serum immunoglobulins due to corticosteroids alone significantly increase susceptibility to infections is unclear, however.

In our patient with COPD on prednisone, if serum IgG level is found to be low and a primary antibody deficiency is still suspected, a functional assessment of the antibody production after active immunization (eg, polysaccharide pneumococcal vaccine, tetanus toxoid) may be necessary. 1 An adequate antibody response to active immunization makes primary immunodeficiency unlikely. 

 

Bonus Pearl: Did you know that corticosteroid-induced hypogammaglobulinemia may be in part related to reduced IgG production as well as an increase in IgG catabolism?1,4

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References

  1. Sarcevic J, Cavelti-Weder C, Berger CT, et al. Case report-secondary antibody deficiency due to endogenous hypercortisolism. Frontiers in Immunology 2020;11:1435. https://www.frontiersin.org/articles/10.3389/fimmu.2020.01435/full
  2. Settipane GA, Pudupakkam RK, McGowan JH. Corticosteroid effect on immunoglobulins. J Allergy Clin Immunol 1978;62: 162-6. https://www.jacionline.org/article/0091-6749(78)90101-X/pdf
  3. Wirsum C, Glaser C, Gutenberger S, et al. Secondary antibody deficiency in glucocorticoid therapy clearly differs from primary antibody deficiency. J Clin Immunol 2016;36:406-12. https://link.springer.com/article/10.1007/s10875-016-0264-7
  4. McMillan R, Longmire R, Yelenosky R. The effect of corticosteroids on human IgG synthesis. J Immunol 1976;116:1592-1595. https://www.jimmunol.org/content/116/6/1592

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

My patient with COPD on prednisone with recurrent pneumonia has a low serum IgG level.  Can corticosteroids lower serum immunoglobulin levels?

What’s the latest on second Covid vaccine boosters and should I recommend them to my adult patients?

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

On March 29, 2022, the CDC and the FDA approved second booster shots of Pfizer and Moderna Covid vaccines for everyone 50 years of age or older as well as people 12 years of age or older with moderate to severe immune deficiencies to be given at least 4 months following the first booster.1-3  This means a 4th dose of an mRNA vaccine for many adults and a 5th dose for those with moderate to severe immune deficiencies. 

Admittedly, these recommendations are made in the context of many uncertainties, including when the next Covid surge will arrive, what will be the predominant variant, and how will our immunity hold up if a surge occurs. 

Nevertheless, in discussing the merits of a 2nd booster, I would emphasize several “talking points”:

  • Covid hasn’t gone away with new cases still diagnosed daily, some still  requiring hospitalization, albeit at lower frequency than recent past. 
  • Our immunity against Covid wanes in the absence of boosters or natural infection.
  • SARS-CoV-2 has been unpredictable in its surges, as well as emergence of new variants with frequent changes in its virulence and ease of transmission. This means we don’t know when the next surge will hit us (summer, fall or later) and how the predominant variant will behave.
  • But let’s not get too hung up on surges! The fact is that as long as Covid is circulating around, maintaining a robust immunity against infection is the best way to avoid getting infected and the best way to do this is through boosters!
  • As more people go around without masks, the risk of unprotected exposure to SARS-CoV-2 is also likely to increase, particularly in indoor public gatherings.  Boosters may allow us the freedom to go maskless more often!
  • The risk of Long Covid even following mild infection is still real even between surges. This means even if we don’t get very sick from Covid, we are placing ourselves at risk of Long Covid. Remember, no Covid, no Long Covid!
  • Irrespective of whether it’s mild or even asymptomatic, Covid infection  can cause significant disruption in our lives, whether it be isolation at home, not being allowed to return to work or just the anxiety of having it or having passed it to others. This means that, at least currently, it’s premature to consider this virus as “just another respiratory virus.”  It’s impact on our everyday lives is still a lot different than typical respiratory viruses. 
  • mRNA vaccine boosters have been proven to be as safe as primary series. 
  • Last, but not the least, a preprint Israeli study involving volunteers 60 to 100 years old found a 78% reduction in mortality from Covid following a 2nd booster dose of Pfizer mRNA vaccine compared to those who only had 1 booster.4  This study has several limitations including self-selected volunteers who may already be at lower risk of Covid mortality due to their healthier lifestyle. Nevertheless, the data is very encouraging!

Ultimately, the decision to get a second booster, particularly during non-surge periods, will depend a lot on not only available facts but the individual’s threshold for acceptable risk of even mild disease, concern over transmission to others and more recently the cost of the vaccine, among other factors.  

Bonus Pearl: Did you know that each year there are plenty of uncertainties around which influenza A or B subtypes will be the predominant seasonal strain or what month they may surge but these questions never keep us from recommending the annual flu vaccine to the public as a means of reducing influenza cases and saving lives?   

 

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References

  1. D.A. Allows Second Covid Boosters for Everyone 50 and Older – The New York Times (nytimes.com)
  2. Coronavirus (COVID-19) Update: FDA Authorizes Second Booster Dose of Two COVID-19 Vaccines for Older and Immunocompromised Individuals | FDA
  3. CDC Recommends Additional Boosters for Certain Individuals | CDC Online Newsroom | CDC
  4. Arbel R, Sergienko R, Friger M, et al. Second booster vaccine and Covid-19 mortality in adults 60-100 years old. Preprint, posted March 24, 2022. 24514bba-2c9d-4add-9d8f-321f610ed199.pdf (researchsquare.com)

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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’s the latest on second Covid vaccine boosters and should I recommend them to my adult patients?

Should healthy adults receive a Covid vaccine booster shot and why?

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

A booster shot of Covid vaccine (eg, mRNA, Pfizer or Moderna) is now recommended by the CDC even for healthy adults as follows:1

  • If you received Pfizer vaccine as your primary series, are ≥12 years old and at least 5 months after your 2nd dose
  • If you received Moderna vaccine as your primary series, are ≥18 years old and at least 5 months after your 2nd dose
  • If you received J&J vaccine, are ≥18 years old and at least 2 months after your 1st dose

There are at least 3 reasons for receiving a Covid vaccine booster: 1

  • Waning immunity after primary vaccine series
  • Emergence of Omicron variant which seems to be less responsive to the existing immunity from the vaccine
  • Recent data from clinical trials showing that a booster shot increased the immune response in trial participants who completed an either Pfizer or Moderna mRNA vaccine primary series 6 months earlier or had J&J vaccine single dose 2 months earlier

Here is the data from CDC on the vaccine effectiveness against Covid based on epidemiologic data on emergency department (ED)/urgent care (UC) encounters or hospitalization during the recent Omicron-predominant period:2

 Vaccine effectiveness against ED/Urgent care encounters 

  • 2 doses of mRNA vaccine: 41% (69% <2 months vs 37% ≥5 months after last dose)
  • 3 doses of mRNA vaccine: 83% (87% < 2 months vs 66% 4 months vs 31% ≥5 months)

Vaccine effectiveness against hospitalization 

  • 2 doses of mRNA vaccine: 55% (71% < 2months vs 54% ≥5 months)
  • 3 doses of mRNA overall 88% (91% if < 2 months, 78% if ≥4 months)

So take full advantage of available Covid vaccines and maximize your chance of not getting Covid!

 

Bonus Pearl: Did you know that a recent CDC study found that people 18 years and older who received the same mRNA vaccine brand for all their vaccinations experienced fewer adverse reactions following the booster dose than they did after their second dose of mRNA vaccine, with 92% of reported reactions not considered serious?3

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References

  1. Covid-19 vaccine booster shots. Feb 2, 2022. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html#:~:text=It%20depends.,after%20the%20J%26J%2FJanssen%20vaccine. Accessed Feb 24, 2022
  2. Waning 2-dose and 3-dose effectiveness of mRNA vaccines against Covid-19-associated emergency department and urgent care encounters and hospitalizations among adults during periods of delta and omicron variant predominance-VISION network, 110 states, August 2021-Jan 2022. Feb 18, 2022 https://www.cdc.gov/mmwr/volumes/71/wr/mm7107e2.htm#T1_down. Accessed Feb 24, 2022.
  3. New CDC studies: Covid-19 boosters remains safe, continue to offer high levels of protection against severe disease over time and during Omicron and delta waves. Feb 11, 2022. https://www.cdc.gov/media/releases/2022/s0211-covid-19-boosters.html. Accessed Feb 24, 2022

 

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, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. 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!

Should healthy adults receive a Covid vaccine booster shot and why?