My previously healthy patient is admitted with a multi-drug resistant E. coli urinary tract infection. Could her urinary tract infection (UTI) be foodborne?

Yes! Although foodborne infections are often thought to cause infections limited to the GI tract, an increasing number of studies have linked foodborne E.coli to extraintestinal infections in humans, including UTIs.1

Supportive data include frequent genetic similarly between antimicrobial-resistant E. coli from humans and poultry-associated E. coli. 2 In fact, antimicrobial-resistant E. coli isolates from humans may be  genetically more similar to poultry isolates than susceptible commensal E. coli strains in the human GI tract.3

A U.S. study found that 14% of chicken meat products were contaminated with E. coli strains capable of causing extraintestinal disease, 1/3 of which were mutli-drug resistant.4  Another study found that 94% of retail chicken meat samples contained E. coli with ESBL-genes,  of which nearly 40% contained isolates present in humans.5

Among women, UTI caused by antimicrobial-resistant extraintestinal pathogenic E. coli has been linked to high levels of self-reported chicken consumption.6

The plausibility of foodborne transmission of antimicrobial-resistant E. coli to humans is further supported by the finding that drug resistant E coli from chicken carcasses widely contaminate the kitchen during meal preparation and can appear in the intestinal tract of those who prepare such food.2

Bonus Pearl: Did you know that women with multi-drug resistant E. coli UTI are 3.7 times more likely to report frequent consumption of chicken? 6

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

References

  1. Manges AR. Escherichia coli and urinary tract infections: the role of poultry-meat. Clin Microbiol Infect 2016;22:122-29. https://www.ncbi.nlm.nih.gov/pubmed/26679924
  2. Manges AR, Johnson JR. Reservoirs of extraintestinal pathogenic Escherichia coli. Microbiol Spectrum 2012;3(5):UTI-0006-2012. https://www.ncbi.nlm.nih.gov/pubmed/26542041
  3. Johnson JR, Menard M, Johsnton B, et al. Epidemic clonal groups of Escherichia coli as a cause of antimicrobial-resistant urinary tract infections in Canada, 2002 to 2004. Antimicrob Agents Chemother 53;2733-2739. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704706/
  4. Johnson JR, Porter SB, Johnston B, et al. Extraintestinal pathogenic and antimicrobial-resistant Escherichia coli, including sequence type 131 (ST131) from retail chicken breasts in the United States in 2013. Apppl Environ Microbiol 83:e02956-16. https://www.ncbi.nlm.nih.gov/pubmed/28062464
  5. Leverstein-van Hall MA, Dierikx CM, Stuart JC, et al. Dutch patients, retail chicken meat and poultry share the same ESBL genes, plasmids and strains. Clin Microbiol Infect 2011;17:873-880. https://www.ncbi.nlm.nih.gov/pubmed/21463397
  6. Manges AR, Smith SP, Lau BJ, et al. Retail meat consumption and the acquisition of antimicrobial resistant Escherichia coli causing urinary tract infections: a case-control study. Foodborne Path Dis 4:419-431. https://www.ncbi.nlm.nih.gov/pubmed/18041952

 

My previously healthy patient is admitted with a multi-drug resistant E. coli urinary tract infection. Could her urinary tract infection (UTI) be foodborne?

Why has my patient with Clostridium difficile diarrhea developed Klebsiella bacteremia?

Although there are many potential sources for Klebsiella sp. bacteremia, C. difficile infection (CDI) itself may be associated with GI translocation of enteric organisms.

A retrospective study of over 1300 patients found an incidence of 1.8% for CDI-associated bacteremia. E. coli, Klebsiella sp. , or Enterococcus sp. accounted for 72% of cases. History of malignancy, neutropenia (at the time of CDAD), and younger age (mean 59 y) were among the risk factors.1 Another study reported over 20 cases of bacteremia caused by C. difficile plus other bacteria often of enteric origin such the aforementioned organisms, Bacteroides sp, Candida sp, and Enterobacter sp.2

CDI is thought to predispose to bacterial translocation through the GI tract by alteration of mucosal indigenous microflora, overgrowth of certain pathogens, and presence of inflammation in the mucosa.3 Interestingly, C. difficile toxin A or B may play an active role in the bacterial adherence and penetration of the intestinal epithelial barrier.4  

Bonus pearl: Did you know that C. difficile may be found in the normal intestinal flora of 3% of healthy adults, 15-30% of hospitalized patients, and up to 50% of neonates? Why neonates seem immune to CDI is another fascinating story!

 

References

  1. Censullo A, Grein J, Madhusudhan M, et al. Bacteremia associated with Clostridium difficile colitis: incidence, risk factors, and outcomes. Open Forum Infectious Diseases, Volume 2, Issue suppl_1, 1 December 2015, 943, https://doi.org/10.1093/ofid/ofv133.659 https://academic.oup.com/ofid/article/2/suppl_1/943/2635179
  2. Kazanji N, Gjeorgjievski M, Yadav S, et al. Monomicrobial vs polymicrobial Clostridum difficile bacteremia: A case report and review of the literature. Am J Med 2015;128:e19-e26. https://www.amjmed.com/article/S0002-9343(15)00458-1/abstract
  3. Naaber P, Mikelsaar RH, Salminen S, et al. Bacterial translocation, intestinal microflora and morphological changes of intestinal mucosa in experimental models of Clostridium difficile infection. J Med Microbiol 1998; 47: 591-8. https://www.ncbi.nlm.nih.gov/pubmed/9839563 
  4. Clostridium difficile toxins may augment bacterial penetration of intestinal epithelium. Arch Surg 1999;134: 1235-1242. https://jamanetwork.com/journals/jamasurgery/fullarticle/390434
Why has my patient with Clostridium difficile diarrhea developed Klebsiella bacteremia?

My patient with pyelonephritis has positive blood cultures for E. coli? Should I order repeat blood cultures to make sure the bacteremia is clearing?

Although a common practice, follow-up blood cultures (FUBCs) may not be necessary in otherwise clinically stable or improving patients with aerobic gram-negative bacteremia. This is probably due to the often-transient nature of gram-negative bloodstream infections  and less propensity of these organisms to cause intravascular infections (eg, endocarditis) compared to gram-positives. 1

A 2017 study addressing the value of FUBCs in gram-negative bacteremia found that repeat positive blood cultures were uncommon with positive results not associated with mortality or higher ICU admissions. 1 Specifically, 17 FUBCs had to be drawn to yield 1 positive result.  Although the numbers of positive FUBCs were too low for in-depth analysis, it was concluded that FUBCs added little value in the management of gram-negative bacteremias.

In contrast, FUBCs are recommended in the following situations: 1-3

  • Staphylocccus aureus bacteremia given the propensity of this organism to cause intravascular (eg, endocarditis) and metastatic infections.
  • Presumed or documented endocarditis or intravascular device infections (eg, intravenous catheters and pacemakers) to document timely clearance of bacteremia
  • Infections involving organisms that may be difficult to clear such as fungemia or multi-drug resistant pathogens.

As with many things in medicine, clinical context is important before ordering tests and blood cultures are no different. The urge to order FUBCs should also be balanced with the possibility of having to deal with  contaminants. 

References

  1. Canzoneri CN, Akhavan BJ, Tosur Z et al. Follow-up blood cultures in gram-negative bacteremia: Are they needed? Clin Infect Dis 2017;65:1776-9. https://www.ncbi.nlm.nih.gov/pubmed/29020307
  2. Tabriz MS, Riederer K, Baran J, et al. Repeating blood cultures during hospital stay: Practice pattern at a teaching hospital and a proposal for guidelines. Clin Microbiol Infect 2004;10:624-27. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1469-0691.2004.00893.x
  3. Mylotte JM, Tayara A. Blood cultures: Clinical aspects and controversies. Eur J Clin Microbiol Infect Dis 200;19:157-63. https://www.ncbi.nlm.nih.gov/pubmed/10795587

 

 

My patient with pyelonephritis has positive blood cultures for E. coli? Should I order repeat blood cultures to make sure the bacteremia is clearing?

200 pearls and counting! Take the Pearls4Peers quiz #2!

Multiple choice (choose 1 answer)
1. Which of the following classes of antibiotics is associated with peripheral neuropathy?
a. Penicillins
b. Cephalosporins
c. Macrolides
d. Quinolones

 

 

2. The best time to test for inherited thrombophilia in a patient with acute deep venous thrombosis is…
a. At least 1 week after stopping anticoagulants and a minimum of 3 months of anticoagulation
b. Just before initiating anticoagulants
c. Once anticoagulation takes full effect
d. Any time, if suspected

 

 

3. All the following is true regarding brain MRI abnormalities following a seizure, except…
a. They are observed following status epilepticus only
b. They are often unilateral
c. They may occasionally be associated with leptomeningeal contrast enhancement
d. Abnormalities may persist for weeks or months

 

 

4. Which of the following is included in the quick SOFA criteria for sepsis?
a. Heart rate
b. Serum lactate
c. Temperature
d. Confusion

 

 

5. All of the following regarding iron replacement and infection is true, except…
a. Many common pathogens such as E.coli and Staphylococcus sp. depend on iron for their growth
b. Association of IV iron replacement and increased risk of infection has not been consistently demonstrated
c. A single randomized-controlled trial of IV iron in patients with active infection failed to show increased infectious complications or mortality with replacement
d. All of the above is true

 

True or false

1. Constipation may precede typical manifestations of Parkinson’s disease by 10 years or more
2. Urine Legionella antigen testing is >90% sensitive in legionnaire’s disease
3. Spontaneous coronary artery dissection should be particularly suspected in males over 50 years of age presenting with acute chest pain
4. Urine dipstick for detection of blood is >90% sensitive in identifying patients with rhabdomyolysis and CK >10,000 U/L
5. Diabetes is an independent risk factor for venous thrombophlebitis

 

 

 

Answer key
Multiple choice questions:1=d; 2=a;3=a;4=d;5=c
True or false questions:1=True; 2,3,4,5=False

 

200 pearls and counting! Take the Pearls4Peers quiz #2!

Is iron therapy contraindicated in my patient with active infection?

In the absence of randomized-controlled trials of iron therapy in patients with active infection, the harmful effects of iron therapy (IT) in this setting remains more theoretical than proven. 1,2

Although many pathogens (eg, E. coli, Klebsiella, Salmonella, Yersinia, and Staphylococcus species) depend on iron for their growth2,3, and iron overload states (eg, hemochromatosis) predispose to a variety of infections, studies evaluating the risk of infection with iron therapy have reported conflicting results.1-4 A 2015 systematic review and meta-analysis of 103 trials comparing IV iron therapy  with several other approaches, including oral iron therapy or placebo, found no increased risk of infections with IV iron.5 In contrast, an earlier systematic review and meta-analysis involving fewer number of trials found an increased risk of infections with IV iron. 6

These varied results are perhaps not surprising since the effects of iron therapy on the risk of infection is likely to be context-specific, depending on the patient’s preexisting iron status, exposure to potential infections and co-infection and genetic background. 4 Of interest, mice with sepsis have worse outcomes when treated with IV iron.7

Perhaps the most prudent approach is to hold off on iron therapy until the active infection is controlled, unless the benefits of urgent iron therapy is thought to outweigh its theoretical harmful effects.

 

Liked this post? Sign up under MENU and catch future pearls in your inbox!

 

References

  1. Daoud E, Nakhla E, Sharma R. Is iron therapy for anemia harmful in the setting of infection? Clev Clin J Med 2011;78:168-70. http://www.mdedge.com/ccjm/article/95480/hematology/iron-therapy-anemia-harmful-setting-infection
  2. Hain D, Braun M. IV iron: to give or to hold in the presence of infection in adults undergoing hemodialysis. Nephrology Nursing Journal 2015;42:279-83. https://www.ncbi.nlm.nih.gov/pubmed/26207288
  3. Jonker FAM, van Hensbroek MB. Anaemia, iron deficiency and susceptibility of infections. J Infect 204;69:523-27. https://www.ncbi.nlm.nih.gov/pubmed/28397964
  4. Drakesmith H, Prentice AM. Hepcidin and the iron-infection axis. Science 2012;338:768-72. https://www.ncbi.nlm.nih.gov/pubmed/23139325  
  5. Avni T, Bieber A, Grossman A, et al. The safety of intravenous iron preparations: systematic review and meta-analysis. Mayo Clin Proc 2015;90:12-23. http://www.mayoclinicproceedings.org/article/S0025-6196(14)00883-0/pdf
  6. Litton E, Xiao J, Ho KM. Safety and efficacy of intravenous iron therapy in reducing requirement for allogeneic blood transfusion: systematic review and meta-analysis of randomized clinical trials. BMJ 2013;347:f4822. https://www.ncbi.nlm.nih.gov/pubmed/23950195
  7. Javadi P, Buchman TG, Stromberg PE, et al. High dose exogenous iron following cecal ligation and puncture increases mortality rate in mice and is associated with an increase in gut epithelial and splenic apoptosis. Crit Care Med 2004;32:1178-1185. https://www.ncbi.nlm.nih.gov/pubmed/15190970
Is iron therapy contraindicated in my patient with active infection?

Are two sets of blood cultures adequate for evaluation of bacteremia in my febrile patient?

For great majority of patients, more than 2 sets of blood culture obtained closely apart is not likely to significantly improve the yield of detecting bacteremia. 

Although a 2004 report suggested that 2 sets of blood cultures over 24 h period had a sensitivity of only 80% for bacteremia, several other studies have found much higher sensitivities, ranging from ~90%- 99% 2-3. When broken down by organism, sensitivity of 2 sets of blood cultures may be highest for Staphylococcus aureus (97%), followed by E. coli (91%), and Klebsiella pneumoniae (90%) 2.  The Clinical and Laboratory Standards Institute guidelines recommend paired blood culture sets (each set with 2 bottles, 10 ml of blood in each) to detect about 90-95% of patients with documented bacteremia, and 3 sets for 95-99% detection rate 4.

It seems prudent to strike a balance between drawing more than 2 sets of blood cultures—with its attendant risk of picking up contaminants— and what may be a definite but small incremental increase in the rate of detection of true bacteremia. 

If you are concerned about “continuous” bacteremia (eg, in endocarditis) or a common blood culture contaminant causing true disease (eg, Staphylococcus epidermidis prosthetic valve infection), you may consider a 3rd or 4th set of blood cultures drawn 4-6 hrs after the initial sets.

Whatever you do,  please don’t order only 1 set of blood cultures! Aside from its generally low yield, when positive it may be difficult to distinguish contaminants from true invaders.

 

References

  1. Cockerill FR, Reed GS, Hughes JG, et al. Clinical comparison of BACTEC 9240 Plus Aerobic/F resin bottles and the Isolator aerobic cultures. Clin Infect Dis 2004;38:1724-30. https://www.ncbi.nlm.nih.gov/pubmed/9163464
  2. Lee A, Mirrett S, Reller LB, et al. Detection of bloodstream infections in adults: how many cultures are needed? J Clin Microbiol 2007; 45:3546-48. http://jcm.asm.org/content/45/11/3546
  3. Towns ML, Jarvis WR, Hsueh PR. Guidelines on blood cultures. J Microbiol Immunol Infect 2010;43:347-49. https://www.ncbi.nlm.nih.gov/pubmed/20688297
  4. Weinstein MP, Reller LB, Murphy JR, et al. The clinical significance of positive blood cultures: a comprehensive analysis of 500 episodes of bacteremia and fungemia in adults. I. Laboratory and eipidemiologic observations. Rev Infect Dis 1982;5:35-53. https://www.ncbi.nlm.nih.gov/pubmed/6828811
Are two sets of blood cultures adequate for evaluation of bacteremia in my febrile patient?

My patient with cirrhosis and suspected infection has a normal serum C-reactive protein (CRP). Does cirrhosis affect CRP response to infection?

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.

Liked this post? Download the app on your smart phone and sign up under MENU to catch future pearls right into your inbox!

References

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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

 

My patient with cirrhosis and suspected infection has a normal serum C-reactive protein (CRP). Does cirrhosis affect CRP response to infection?

My patient with acute onset headache, photophobia, and neck stiffness does not have CSF pleocytosis. Could she still have meningitis?

Although the clinical diagnosis of meningitis is often supported by the presence of abnormal number of WBCs in the CSF (AKA pleocytosis), meningitis may be present despite its absence.

Among viral causes of meningitis in adults, enteroviruses are associated with lower CSF WBC count compared to herpes simplex and varicella zoster, with some patients (~10%) having 0-2 WBC’s/mm31,2.  Of interest, among children, parechovirus (formerly echovirus 22 and 23) meningitis is characterized by normal CSF findings3.

Though uncommon, bacterial meningitis without CSF pleocytosis has been reported among non-neutropenic adults,  including Neisseria meningitidis, Streptococcus pneumoniae, Hemophilus influenzae, Listeria monocytogenes, E. coli, and Proteus mirabilis4A European study also reported normal CSF WBC in nearly 10% of patients with Lyme neuroborreliosis (including meningitis) caused primarily by Borrelia garinii5.

Cryptococcal meninigitis may also be associated with normal CSF profile in 25% of patients with HIV infection6.

 

References

  1. Ihekwaba UK, Kudesia G, McKendrick MW. Clinical features of viral meningitis in adult:significant differences in cerebrospinal fluid findings among herpes simplex virus, varicella zoster virus, and enterovirus infections. Clin Infect Dis 2008;47:783-9. https://www.ncbi.nlm.nih.gov/pubmed/18680414
  2. Dawood N, Desjobert E, Lumley J et al. Confirmed viral meningitis with normal CSF findings. BMJ Case Rep 2014. Doi:10.1136/bcr-2014-203733. http://casereports.bmj.com/content/2014/bcr-2014-203733.abstract
  3. Wolthers KC, Benschop KSM, Schinkel J, et al. Human parechovirus as an important viral cause of sepsis like illness and meningitis in young children. Clin Infect Dis 2008;47:358-63. https://www.ncbi.nlm.nih.gov/pubmed/18558876
  4. Hase R, Hosokawa N, Yaegashi M, et al. Bacterial meningitis in the absence of cerebrospinal fluid pleocytosis: A case report and review of the literature. Can J Infect Dis Med Microbiol 2014;25:249:51. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4211346/pdf/idmm-25-249.pdf
  5. Ogrinc K, Lotric-Furlan S, Maraspin  V, et al. Suspected early Lyme neuroborreliosis in patients with erythema migrans. Clin Infect Dis 2013; 57:501-9. https://www.ncbi.nlm.nih.gov/pubmed?term=23667259
  6. Darras-Joly C, Chevret S, Wolff M, et al. Cryptococcus neoformans infection in France: epidemiologic features of and early prognostic parameters for 76 patients who were infected with human immunodeficiency virus. Clin Infect Dis 1996;23:369-76. https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/cid/23/2/10.1093/clinids/23.2.369/2/23-2-369.pdf?Expires=1501035620&Signature=FhHMHUHAMmT3rz4ld8QAMet-weu-BWgm5YR6nA4jjSGVGIeaVlMNPgeOkW2fniiel54HQhIs1Kkp3PpzT1glxhJeZvQiGXQCSOoF-jS1SK7S~kBb-oHs4qsIJzN0OJxNAXfoJi4bl7OeKaLTyIE3P8~slwH0BBi7RncSYVgVR4NkOnFpYgn27~wY7pDSUNWvzGFKoSeYGeM0TsAqna-QmXzodITB5bgr1mO6Q6OGUxCsqRwhr6xNb~4G93oqRcsO19gyUluCE0xYt0KbKWuQxJeh8AbtJkNrS08~XInMR50bQZOUb80j0~dtg9jRTGzXQaDllVByoX2Alr48hlhogw__&Key-Pair-Id=APKAIUCZBIA4LVPAVW3Q
My patient with acute onset headache, photophobia, and neck stiffness does not have CSF pleocytosis. Could she still have meningitis?