You don’t have too! Although “bacteriostatic” antibiotics have traditionally been regarded as inferior to “bactericidal” antibiotics in the treatment of serious infections, a 2018 “myth busting” systemic literature review1 concluded that bacteriostatic antibiotics are just as effective against a variety of infections, including pneumonia, non-endocarditis bacteremia, skin and soft tissue infections and genital infections; no conclusion can be made in regards to endocarditis or bacterial meningitis, however, due insufficient clinical evidence.1-3
Interestingly, most of the studies included in the same systemic review showed that bacteriostatic antibiotics were more effective compared to bactericidal antibiotics.1 So, for most infections in hospitalized patients, including those with non-endocarditis bacteremia, the choice of antibiotic among those that demonstrate in vitro susceptibility should not be based on their “cidal” vs “static” label.
Such conclusion should not be too surprising since the definition of bacteriostatic vs bactericidal is based on arbitrary in vitro constructs and not validated by any available in vivo data. In addition, static antibiotics may kill bacteria as rapidly as cidal antibiotics in vitro at higher antibiotic concentrations.3
Another supportive evidence is a 2019 study finding similar efficacy of sequential intravenous-to-oral outpatient antibiotic therapy for MRSA bacteremia compared to continued IV antibiotic therapy despite frequent use of bacteriostatic oral antibiotics (eg, linezolid, clindamycin and doxycycline). 4
- Wald-Dickler N, Holtom P, Spellberg B. Busting the myth of “static vs cidal”: as systemic literature review. Clin Infect Dis 2018;66:1470-4. https://academic.oup.com/cid/article/66/9/1470/4774989
- Steigbigel RT, Steigbigel NH. Static vs cidal antibiotics. Clin Infect Dis 2019;68:351-2. https://academic.oup.com/cid/article-abstract/68/2/351/5067395
- Wald-Dickler N, Holtom P, Spellberg B. Static vs cidal antibiotics; reply to Steigbigel and Steigbigel. Clin Infect Dis 2019;68:352-3. https://academic.oup.com/cid/article-abstract/68/2/352/5067396?redirectedFrom=fulltext
- Jorgensen SCJ, Lagnf AH, Bhatia S, et al. Sequential intravenous-to-oral outpatient antbiotic therapy for MRSA bacteraemia: one step closer. J Antimicrob Chemother 2019;74:489-98. https://www.ncbi.nlm.nih.gov/pubmed/30418557
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Yes! Ample epidemiological studies implicate infection as an important risk factor for MI.1 The increased risk of MI has been observed during the days, weeks, months or even years following an infection.
A 2018 paper reported a several-fold risk of MI during the week after laboratory-confirmed infection caused by a variety of respiratory pathogens such as influenza virus (6-fold), respiratory syncytial virus (4-fold), and other respiratory viruses (3-fold). 2 Among patients hospitalized for pneumococcal pneumonia, 7-8% may suffer an MI.3,4 One study found a 48-fold increase in the risk of MI during the first 15 days after hospitalization for acute bacterial pneumonia.5 Similarly, an increase in the short-term risk of MI has been observed in patients with urinary tract infection and bacteremia.6
The risk of MI appears to be the highest at the onset of infection and correlates with the severity of illness, with the risk being the highest in patients with pneumonia complicated by sepsis, followed by pneumonia and upper respiratory tract infection. Among patients with pneumonia, the risk exceeds the baseline risk for up to 10 years after the event, particularly with more severe infections.1
Potential mechanisms of MI following infections include release of inflammatory cytokines (eg, interleukins 1, 6, tumor necrosis factor alpha) causing activation of inflammatory cells in atherosclerotic plaques, in turn resulting in destabilization of the plaques. In addition, the thrombogenic state of acute infections, platelet and endothelial dysfunction may increase the risk of coronary thrombosis at sites of plaque disruption beyond clinical resolution of the acute infection. 1
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- Musher DM, Abers MS, Corrales-Medina VF. Acute infection and myocardial infarction. N Engl J Med 2019;380:171-6. https://www.ncbi.nlm.nih.gov/pubmed/30625066
- Kwong JC, Schwartz KL, Campitelli MA, et al. Acute myocardial infarction after laboratory-confirmed influenza infection. N Engl J Med 2018;378:345-53. https://www.nejm.org/doi/full/10.1056/NEJMoa1702090
- Musher DM, Alexandraki I, Graviss EA, et al. Bacteremic and nonbacteremic pneumococcal pneumonia: a prospective study. Medicine (Baltimore) 2000;79:210-21. https://www.ncbi.nlm.nih.gov/pubmed/10941350
- Musher DM, Rueda Am, Kaka As, Mapara SM. The association between pneumococcal pneumonia and acute cardiac events. Clin Infect Dis 2007;45:158-65. https://www.ncbi.nlm.nih.gov/pubmed/17578773
- Corrales-Medina VF, Serpa J, Rueda AM, et al. Acute bacterial pneumonia is associated with the occurrence of acute coronary syndromes. Medicine (Baltimore) 2009;88:154-9. https://www.ncbi.nlm.nih.gov/pubmed/19440118
- Dalager-Pedersen M, Sogaard M, Schonheyder HC, et al. Risk for myocardial infarction and stroke after community-acquired bacteremia: a 20-year population-based cohort study. Circulation 2014;129:1387-96. https://www.ncbi.nlm.nih.gov/pubmed/24523433
Although fosfomycin (FM) has been approved by the FDA only for the treatment of uncomplicated urinary tract infection (UTI) in women, it may also have a role in the treatment of acute and chronic prostatitis among males given its favorable levels in the prostate tissue. 1-5
Despite lack of studies comparing the efficacy of FM with that of commonly used antibiotics for treatment of prostatitis, the potential utility of FM is supported by several reports of its efficacy in the treatment of prostatitis, including those caused by extended-spectrum beta-lactamase (ESBL)-producing gram-negative rods. 1,4-5
When considering FM for treatment of prostatitis, a higher dose than customary may be needed (3 g once daily, not every 48-72 h) . 4 Although the optimal duration of therapy with FM is unclear in this setting, 12-16 weeks of therapy was used in 2 patients with recurrent UTIs and prostatitis due to multi-drug resistant ESBL-positive E. coli. 4
Given its pharmacokinetics and lack of proven efficacy, avoid FM in pyelonephritis, perinephric abscess or UTI with bacteremia. 2
- Falagas ME, Vouloumanou EK, Samonis G, et al. Fosfomycin. Clin Microbiol Rev 2016;29:321-347. https://www.ncbi.nlm.nih.gov/pubmed/26960938
- Wankum M, Koutsari C, Gens K. Fosfomycin use. Pharmacy Times. November 30, 2017. https://www.pharmacytimes.com/publications/health-system-edition/2017/november2017/fosfomycin-use
- Cunha BA, Gran A, Raza M. Persistent extended-spectrum β-lactamase-positive Escherechia coli chronic prostatitis successfully treated with a combination of fosfomycin and doxycycline. International J Antimicrob Agents 2015;45:427-29. https://www.ncbi.nlm.nih.gov/pubmed/25662814
- Grayson ML, Macesic N, Trevillyan J, et al. Fosfomycin for treatment of prostatitis: new tricks for old dogs. Clin Infect Dis 2015;61:1141-3. https://www.ncbi.nlm.nih.gov/pubmed/26063723
- Falagas ME, Rafailidis PI. Fosfomycin: the current status of the drug. Clin Infect Dis 2015;61:1144-6. https://www.ncbi.nlm.nih.gov/pubmed/26063717
Although IV drug use (IVDU) is associated with febrile illness of numerous etiologies (eg, soft tissue infections, pneumonia, bacteremia, endocarditis), certain features of a febrile illness may be helpful in considering cotton fever (CF) as the cause.1-3
First, onset of fever—often associated with chills, shortness of breath, nausea, vomiting, headache, abdominal pain and myalgias—in CF is usually manifest within 10-30 minutes of drug injection. Second, infectious disease workup, including blood cultures and chest radiograph, are unrevealing despite clinical signs of systemic inflammatory response syndrome (SIRS), such as leukocytosis, tachypnea and tachycardia. Third, symptoms and clinical signs of inflammation usually resolve or improve within 6-12 h of onset (less commonly up to 24-48 h). Nevertheless, CF remains a diagnosis of exclusion.
As for the cause of CF, the most widely-held theory revolves around the endotoxin of Pentoea agglomerans (formerly Enterobacter agglomerans), a gram-negative rod that colonizes cotton plants. Since cotton is often used as a filter during injection of illicit substances, any endotoxin present in the cotton is also injected resulting in abrupt onset of a febrile illness. Of note, the toxin is water soluble and heating (often part of the preparation of the drug) enhances its toxic effect.3
- Zerr AM, Ku K, Kara A. Cotton Fever: a condition self-diagnosed by IV drug users. JABFM 2016;29: 276-279.PDF
- Xie Y, Pope BA, Hunter AJ. Cotton fever: does the patient know best? J Gen Intern Med 31:442-4. PDF
- Torka P, Gill S. Cotton fever: an evanescent process mimicking sepsis in an intravenous drug abuser. J Emerg Med 2013;44:e385-e387. PDF
Although for many years Aerococcus urinae was considered a urinary contaminant, increasingly it is recognized as an emerging pathogen capable of causing not only urinary tract infection (UTI) but also secondary bacteremia and endocarditis, among others.1
The proportion of patients with aerococcal bacteriuria with symptoms suggestive of UTI ranges from 55-98%.1 So A. urinae can no longer be assumed to be a contaminant, particularly in the presence of symptoms suggestive of UTI.
A. urinae UTI often affects the elderly (median age 79 y) and those with pre-existing urinary tract pathologies, such as prostatic hyperplasia, urethral stricture, renal calculi, and prior urinary tract surgery.2,3 Many patients also have underlying comorbidities such as diabetes, heart disease, dementia, and chronic renal failure.3
One clue to the presence of A. urinae in the urine is its particularly pungent odor reminiscent of that of patients with trimethylaminuria (fish odor syndrome).4
Once you decide you should treat A. urinae, keep in mind that it is NOT predictably susceptible to trimethoprim-sulfamethoxazole, fluoroquinolones, or fosfomycin! Instead, consider penicillin, ampicillin, cephalosporin, or nitrofurantoin to which most strains are susceptible.5,6.
- Rasmussen M. Aerococcus: an increasingly acknowledged human pathogen. Clin Microbiol Infect 2016;22:22-27. https://www.ncbi.nlm.nih.gov/pubmed/26454061
- Tathireddy H, Settypalli S, Farrell JJ. A rare case of aerococcus urinae infective endocarditis. J Community Hosp Intern Med Perspectives 2017; 7:126-129. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5473194/
- Higgins A, Garg T. Aerococcus urinae: An emerging cause of urinary tract infection in older adults with multimordidity and urologic cancer. Urology Case Reports 2017;24-25. https://www.ncbi.nlm.nih.gov/pubmed/28435789
- Lenherr N, Berndt A, Ritz N, et al. Aerococcus urinae: a possible reason for malodorus urine in otherwise healthy children. Eur J Pediatr. 2014;173:1115-7 https://www.ncbi.nlm.nih.gov/pubmed/24913181
- Christensen JJ, Nielsen XC. Aerococcus urinae. Antimicrobe @ http://www.antimicrobe.orgb75.asp , accessed June 14, 2018.
- Dimitriadi D, Charitidou C, Pittaras T, et al. A case of urinary tract infection caused by Aerococcus urinae. J Bacteriol Mycol 2016; 2: 00041. https://pdfs.semanticscholar.org/a1cf/048d8444ce054ca9a332f7c2b4a218325ff6.pdf
CRP is primarily synthesized by the liver mainly as a response to IL-6 production in inflammatory states1. Lower CRP production may then be expected in cirrhotic patients with significant infections and several studies support this view2.
In a particularly convincing study involving E. coli-infected patients with bacteremia, the median CRP level in cirrhotic patients was about 40% that of non-cirrhotic patients (62 mg/L vs 146 mg/L)3. In another study involving bacteremic patients with or without liver dysfunction, median CRP level was about 60% that of patients with preserved liver function (81 mg/L vs 139 mg/L)4.
Some investigators have reported a cut-off CRP value of 9.2 mg/L as a possible screening test for bacterial infections in patients with cirrhosis with a sensitivity and specificity of 88% (AUROC 0.93)5.
Collectively, these data suggest that although CRP response may be diminished in patients with advanced liver disease and acute infection, its synthesis is still maintained.
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- Pieri G, Agarwal B, Burroughs AK. C-reactive protein and bacterial infection in cirrhosis. Ann Gastroenterol 2014;27:113-20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982625/pdf/AnnGastroenterol-27-113.pdf
- Ha YE, Kang C-I, Joo E-J, et al. Usefulness of C-reactive protein for evaluating clinical outcomes in cirrhotic patients with bacteremia. Korean J Intern Med 2011;26:195-200. http://pubmedcentralcanada.ca/pmcc/articles/PMC3110852/pdf/kjim-26-195.pdf
- Park WB1, Lee KD, Lee CS et al. Production of C-reactive protein in Escherichia coli-infected patients with liver dysfunction due to liver cirrhosis. Diagn Microbiol Infect Dis. 2005 Apr;51(4):227-30. https://www.ncbi.nlm.nih.gov/pubmed/15808312
- Mackenzie I, Woodhouse J. C-reactive protein concentrations during bacteraemia: a comparison between patients with and without liver dysfunction. Intensive Care Med 2006;32:1344-51. https://www.ncbi.nlm.nih.gov/pubmed/16799774
- Papp M, Vitalis Z, Altorjay I, et al. Acute phase proteins in the diagnosis and prediction of cirrhosis associated bacterial infection. Liver Int 2011;603-11. https://www.ncbi.nlm.nih.gov/pubmed/22145664
In the absence of disseminated infection such as meningitis or endocarditis, there is no convincing evidence that bacteremic pneumococcal pneumonia (BPP) requires either longer course of IV or oral antibiotics.
In fact, although previously thought to have a worse prognosis, recent data have failed to demonstrate any difference in time to clinical stability, duration of hospital stay or community-associated pneumonia (CAP)-related mortality with BPP when other factors such as patient comorbidities and severity of disease are also considered1,2.
Although many patients with CAP receive 7-10 days of antibiotic therapy, shorter durations as little as 5 days may also be effective3,4. Generally, once patients with BPP have stabilized on parenteral therapy, a switch to an appropriate oral antibiotic (eg, a β-lactam or a respiratory quinolone such as levofloxacin) can be made safely5.
Although large randomized-controlled studies of treatment of BPP are not available, a cumulative clinical trial experience with levofloxacin for patients with BPP reported a successful clinical response in >90% of patients (median duration of therapy 14 d)6. Resistance to levofloxacin and failure of treatment in pneumococcal pneumonia (with or without bacteremia), however, has been rarely reported7.
- Bordon J, Peyrani P, Brock GN. The presence of pneumococcal bacteremia does not influence clinical outcomes in patients with community-acquired pneumonia. Chest 2008;133;618-624.
- Cilloniz C, Torres A. Understanding mortality in bacteremic pneumococcal pneumonia. J Bras Pneumol 2012;38:419-421.
- Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis 2007;44:S27-72.
- Shorr F, Khashab MM, Xiang JX, et al. Levofloxacin 750-mg for 5 days for the treatment of hospitalized Fine Risk Class III/IV community-acquired pneumonia patients. Resp Med 2006;100:2129-36.
- Ramirez JA, Bordon J. Early switch from intravenous to oral antibiotics in hospitalized patients with bacteremic community-acquired Streptococcus pneumonia pneumonia. Arch Intern Med 2001;161:848-50.
- Kahn JB, Bahal N, Wiesinger BA, et al. Cumulative clinical trial experience with levofloxacin for patients with community-acquired pneumonia-associated pneumococcal bacteremia. Clin Infect Dis 2004;38(supp 1):S34-42.
- Davidson R, Cavalcanti R, Brunton JL, et al. Resistance to levofloxacin and failure of treatment of pneumococcal pneumonia. N Engl J Med 2002;346:747-50.
A common medical myth is that the yield of BCs is highest when obtained around the time of a fever spike. In 1989, an abstract reported a non-significant trend toward higher frequency of positive BCs in the period immediately before a fever spike1. In 1994, another study found no significant difference between the yield of simultaneous and serial (separated by a few hrs) BCs2, supporting the current practice of collecting ≥2 sets of BCs simultaneously.
In 2008, a multicenter retrospective study found that the likelihood of detecting bacteremia was not significantly enhanced by collecting BCs at the time of fever3. Instead, obtaining an adequate blood volume (~40 – 60mL for each episode), and collecting ≥2 sets of BCs under strict aseptic technique were emphasized4. BCs should be obtained prior to antibiotic administration.
So in our patient, BCs should be obtained if sepsis is suspected, irrespective of fever.
- Thomson RB, et al. Timing of blood culture collection from febrile patients. Abstr. C-227. 89th Annual Meeting American Society of Microbiology, Washington, DC, 1989.
- Li J, et al. Effects of volume and periodicity on blood cultures. J Clin Microbiol. 1994; 32:2829-2831.
- Riedel S, et al. Timing of specimen collection for blood cultures from febrile patients with bacteremia. J Clin Microbiol. 2008;46:1381-1385.
- Clinical and Laboratory Standards Institute (CLSI). Principles and Procedures for Blood Cultures: Approved Guideline. 2007. CLSI document M47-A. Clinical and Laboratory Standards Institute, Wayne, PA
Contributed by Henrietta Afari, MD, Mass General Hospital, Boston, MA
In most situations, you will most likely choose an antibiotic based on the laboratory reporting of “Susceptible” (vs “Resistant”), not the actual MIC value of the drug and that’s fine.
However, there may be a few instances when you may need to pay more attention to the actual MICs. Many experts recommend caution when “high” MICs within a susceptible range are observed in the following situations:
- Vancomycin MIC >1 ug/ml in Staphylococcal aureus (methicillin-sensitive or –resistant) infections because of its possible association with clinical failure and, at times, increased mortality1,2.
- Ciprofloxacin or levofloxacin MIC>0.25 ug/ml in bacteremia caused by Gram-negative bacilli (including Enterobacteriacae as well as Pseudomonas aeruginosa) because of its association with an adverse outcome (eg, longer average hospital stay post-culture and duration of infection) but not necessarily mortality3-5.
- Levofloxacin MIC ≥ 1.0 ug/ml in Streptococcus pneumoniae infections, because of its association with an adverse clinical outcome based on drug pharmacodynamics and anecdotal reports of treatment failure6,7.
- Jacob JT, DiazGranados CA. High vancomycin minimum inhibitory concentration and clinical outomces in adults with methicillin-resistant Staphylococcus aureus infections: a meta-analysis. Int J Infect Dis 2013;17:e93-e100. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3780595/
- Kalil AC, Van Schooneveld TC, Fey PD, et al. Association between vancomycin minimum inhibitory concentration and mortality among patients with Staphylococcus aureus bloodstream infections: A systematic review and meta-analysis. JAMA 2014;312:1552-1564. https://www.ncbi.nlm.nih.gov/pubmed/25321910
- DeFife R, Scheetz MH, Feinglass J, et al. Effect of differences in MIC values on clinical outcomes in patients with bloodstream infections caused by Gram-negative organisms treated with levofloxacin. Antimicrob Agents Chemother 2009;53:1074-79. http://aac.asm.org/content/53/3/1074.full
- Falagas ME, Tansarli GS, Rafailidis PI, et al. Impact of antibiotic MIC on infection outcome in patients with susceptible Gram-negative bacteria a systematic review and meta-analysis. Antimicrob Agents Chemother 2012;56:4214-22. https://www.ncbi.nlm.nih.gov/pubmed/22615292
- Zelenitsky SA, Harding GKM, Sun S, et al. Treatment and outcome of Pseudomonas aeruginosa bacteremia: an antibiotic pharmacodynamics analysis. J Antimicrob Chemother 2003;52:668-674. https://www.ncbi.nlm.nih.gov/pubmed/12951354
- Davidson R, Cavalcanti R, Brunton JL, et al. Resistance to levofloxacin and failure of treatment of pneumococcal pneumonia. N Engl J Med 2002;346:. 2002;346:747-50. https://www.ncbi.nlm.nih.gov/pubmed/11882730
- De Cueto M, Rodriguez JM, Soriano MJ, et al. Fatal levofloxacin failure in treatment of a bacteremic patient infected with Streptococcus pneumoniae with a preexisting parC mutation. J Clin Microbiol 2008;46:1558-1560. http://jcm.asm.org/content/46/4/1558.full
Contributed in part by Nick Van Hise, Pharm.D., BCPS, Infectious Diseases Clinical Pharmacist, Edward-Elmhurst Hospitals, Naperville, Illinois.
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Although there are no clinical trials comparing therapy with vancomycin and β-lactam to vancomycin alone in the empiric treatment of S. aureus bacteremia (SAB), combination therapy has been advocated by some based on reports of reduced morbidity and mortality (1). More recently however, a retrospective study involving 122 hospitals failed to find superiority of vancomycin-β-lactam combination therapy compared to vancomycin alone for empiric therapy of SAB (2).
We do know that despite its activity against methicillin-susceptible S. aureus (MSSA), vancomycin is less bactericidal (3), with a higher rate of relapse than anti-staphylococcal β-lactams in the treatment of established SAB (4).
So although it may not be clear if we need to empirically place all of our patients suspected of SAB on a vancomycin-β-lactam from the get go, once MSSA has been confirmed, vancomycin should be dropped in favor of an anti-staphylococcal β-lactam.
- McConeghy KW, Bleasdale SC, Rodvold KA. The empirical combination of vancomycin and a β-lactam for staphylococcal bacteremia. Clin Infect Dis 2013;57:1760-5. https://www.ncbi.nlm.nih.gov/pubmed/23985343
- McDaniel JS, Perencevich EN, Diekema DJ, et al. Comparative effectiveness of beta-lactams versus vancomycin for treatment of methicillin-susceptible Staphylococcus aureus bloodstream infections among 122 hospitals. Clin Infect Dis 2015;61:361-7. https://www.ncbi.nlm.nih.gov/pubmed/25900170
- Fernandez Guerrero ML, de Gorgolas M. Comparative activity of cloxacillin and vancomycin against methicillin-susceptible Staphylococcus aureus experimental endocarditis. J Antimicrob Chemother 2006;58:1066-1069. https://www.ncbi.nlm.nih.gov/pubmed/16931540
- Chang F-Y, Peacock JE, Musher DM, et al. Staphylococcus aureus bacteremia: recurrence and the impact of antibiotic treatment in a prospective multicenter study. Medicine (Baltimore) 2003;82:333-9. https://www.ncbi.nlm.nih.gov/pubmed/14530782