- Email: [email protected]
Aeromonas spp as a causative agent for nosocomial infection in trauma patients
Letters to the Editor
687
heterotypic G9P[4] rotavirus strain in Mexico. J Infect Dis 2011;204:783e6. 10. Anderson EJ, Reddy S, Katz BZ, Noskin GA. Indirect protection and indirect measures of protection from rotavirus in adults. J Infect Dis 2012;205:1762e4. author reply 4e5.
Evan J. Anderson* Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States Deanna B. Shippee Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Jacqueline E. Tate Center for Disease Control and Prevention (CDC), Atlanta, GA, United States Bruce Larkin Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Melissa D. Bregger Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Ben Z. Katz Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Gary A. Noskin Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Bethany K. Sederdahl Andi L. Shane Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States Umesh D. Parashar Center for Disease Control and Prevention (CDC), Atlanta, GA, United States Ram Yogev Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States *Corresponding author. Division of Pediatric Infectious Diseases, 2015 Uppergate, Atlanta, GA 30323, United States. Tel.: þ1 (404) 727 1746; fax: þ1 (404) 727 9223.
E-mail address: [email protected] Accepted 28 November 2014 http://dx.doi.org/10.1016/j.jinf.2014.11.012 ª 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserved.
Aeromonas spp as a causative agent for nosocomial infection in trauma patients
Dear Sir, We read with great interest the review by Parker and Shaw1 highlighting the importance of Aeromonas spp in the causation of human intestinal and extra-intestinal infections. Most of the published reports suggest causation of Aeromonas extra-intestinal infection in immunosuppressed patients or infections after contact with water contaminated with Aeromonas. A retrospective analysis of the clinical and microbiological characteristics of all the Aeromonas strains isolated over a period of seven years (2007e2014) was performed at a 165 bedded, level-1 trauma center of India. To the best of our knowledge no studies have yet been conducted on trauma patients from India or worldover.1e7 All patients who were culture positive for Aeromonas spp were identified from the hospital’s computerized database and their medical records were reviewed. All isolates were identified by Vitek 2 automated system (Biomerieux; France) and antimicrobial susceptibility was performed using the disk diffusion method and by the Vitek 2 AST card. During the study period, a total 78 samples grew Aeromonas on culture, which were obtained from 36 patients. Aeromonas hydrophilla 60(77%) was the most common strain followed by Aeromonas caviae 12(15%); Aeromonas sobria 4(5%) and Aeromonas veronii & Aeromonas salmonicida one strain each (1%). Pus and wound swab 57(73%) were the most common source of Aeromonas spp followed by blood 12(15%) and drain fluid 7(9%). Twenty six(46%) samples of pus and wound swab grew Aeromonas spp as a co-infection with other pathogens. The most common co-pathogen was Pseudomonas aeruginosa 10(13%) followed by Enterobacter spp 8(10%) and Klebsiella pneumonia 7(9%). Acinetobacter baumannii grew as a copathogen in 1(1%) sample. Detailed antimicrobial susceptibility of all the isolates is given in Table 1. Maximum susceptibility was seen to the third generation cephalosporins group of drugs i.e. ceftazidime 44(56.4%), ceftriaxone 44(56.4%) and ceftriaxone/sulbactam 44(56.4%). Twelve (15.4%) patients developed Aeromonas bacteremia secondary to wound infection. Of these, two (5.5%) developed septic shock and died due the same. One (2.7%) patient had trauma at multiple sites at the time of presentation and died of cardiorespiratory arrest due to severe head injury. Two (5.5%) patients developed pneumonia with Aeromonas as the causative pathogen. One (2.7%) of them died due to Acute Respiratory Distress Syndrome. Thus, the total in-hospital mortality was 4(11%). Detailed clinical characteristics of all the patients is described in Table 2. Apart from ours, there is only one case series reported from India by Mukhopadhyay et al.8 in which only eight cases of extraintestinal infections due to Aeromonas have been reported. We found that A. hydrophila was the
688 Table 1 isolates.
Letters to the Editor Antimicrobial susceptibility of the Aeromonas
Antimicrobial agent
Drug resistance (number; percentage)
Ampicillin Chloramphenicol Cefepime Ciprofloxacin Ceftazidime Ceftriaxone Cefotaxime Cefoxitin Gentamicin Imipenem Levofloxacin Meropenem Piperacillin Piperacillin-tazobactam Tigecycline Colistin Cefoperazone-sulbactam Cotrimoxazole Netilmicin Cefepime-tazobactam Ceftriaxone-sulbactam Ticarcillin-clavulanate
22; 14; 28; 36; 44; 44; 38; 72; 24; 6; 28; 10; 36; 32; 10; 32; 40; 52; 8; 12; 44; 42;
28.2 17.9 35.9 2.6 56.4 56.4 48.7 92.3 30.7 7.7 35.9 12.8 46.2 41 12.8 41.02 51.28 66.67 10.26 15.38 56.4 53.8
most common species of aeromonad causing nosocomial infection in trauma patients of our hospital. The results of our study are in collaboration with the results of studies from other parts of the world.1e7
Table 2 Clinical characteristics of patients with Aeromonas infection. Patient characteristic
Number; percentage (n Z 36)
Age; Mean (years); SD Sex (male) ICU admission Initial presentation Necrotizing fasciitis Osteomyelitis Myonecrosis Shock Laboratory findings (mean SD) White blood cell (cells/mL) Aspartate transaminase (IU/L) Total bilirubin (mg/dL) Serum creatinine (mg/dL) Body temperature C (median) range Average length of stay mean; SD (days) Time to culture negativity mean; SD (days) In hospital Mortality Mechanical ventilation
23; 10.99 25; 69.44 8; 22.22 12; 33.33 10; 27.78 6; 16.67 2; 5.55 10,257.4 4808.5 40.2 60.9 1.7 1.5 1.5 1.0 39.8 (37.7e41.8) 62; 35 15; 9 4; 11.1 13; 36.1
Our study, however, disproved the findings of the earlier studies where Aeromonas infection was associated with immunosupression1 as the patient population getting admitted after trauma are representative of healthy population. Our findings suggest that aeromonads can cause skin and soft tissue infections irrespective of the patient’s immune status. In contrast to other studies,1 none of the patients in our study had a history of exposure to aqueous environment prior to infection. However, being a retrospective study, the complete details of all patients could not be retrieved which may be a cause of the discrepancy. A total of 22 (61%) of the patients with SSTI had coinfection, which is consistent with the results of the previous studies.9 However, in contrast to the previous reports, Pseudomonas aeruginosa was the most common copathogen in our study. Thus, the clinicians treating patients with Aeromonas spp should be aware of copathogens and give broad spectrum antibiotics to cover both pathogens. It was difficult to assess the contribution of each organism in patients with co-infection as the mortality rate was low. This study had few limitations. First, the Vitek 2 GN system for Aeromonas species identification might not be accurate enough to identify the isolates to the species level. The accuracy of this commercial system for correct identification is less than 90% at the species level.10 The isolates were also not available for further molecular studies. We did not retest the in vitro susceptibilities of the isolates by the microdilution methods. Most importantly, we could not compare the clinical differences between patients with monomicrobial SSTIs due to Aeromonas species and patients with polymicrobial infections. In conclusion, Aeromonas species are important pathogens causing SSTIs. Most of the infections during the study period were polymicrobial. Empirical antibiotics for patients with Aeromonas infection should be broadspectrum to cover dual infections. No financial support has been obtained for conducting the above study and there is no conflict of interest between the co-authors.
References 1. Parker JL, Shaw JG. Aeromonas spp. clinical microbiology and disease. J Infect 2011;62:109e18. 2. Duthie R, Ling TW, Cheng AF, French GL. Aeromonas septicaemia in Hong Kong species distribution and associated diseases. J Infect 1995;30:241e4. 3. Janda JM, Guthertz LS, Kokka RP, Shimada T. Aeromonas species in septicemia: laboratory characteristics and clinical observations. Clin Infect Dis 1994;19:77e83. 4. Ko WC, Chuang YC. Aeromonas bacteremia: review of 59 episodes. Clin Infect Dis 1995;20:1298e304. 5. Dryden M, Munro R. Aeromonas septicemia: relationship of species and clinical features. Pathology 1989;21:111e4. 6. Hochedez P, Hope-Rapp E, Olive C, Nicolas M, Beaucaure G, A. Bacteremia caused by Aeromonas species [corrected] Cabie complex in the Caribbean Islands of Martinique and Guadeloupe. Am J Trop Med Hyg 2010;83:1123e7. 7. Lay CJ, Zhuang HJ, Ho YH, Tsai YS, Wang LS, Tsai CC. Different clinical characteristics between polymicrobial and monomicrobial Aeromonas bacteremiada study of 216 cases. Intern Med 2010;49:2415e21.
Letters to the Editor
689
8. Mukhopadhyay C, Chawla K, Sharma Y, Bairy I. Emerging extraintestinal infections with Aeromonas hydrophila in coastal region of southern Karnataka. J Postgrad Med 2008;54(3): 199e202. 9. Janda JM, Abbott SL. The genus Aeromonas: taxonomy, pathogenicity, and infection. Clin Microbiol Rev 2010;23:35e73. 10. Ling TK, Tam PC, Liu ZK, Cheng AF. Evaluation of VITEK 2 rapid identification and susceptibility testing system against gramnegative clinical isolates. J Clin Microbiol 2001;39:2964e6.
Priyam Batra Purva Mathur* M.C. Misra All India Institute of Medical Sciences, New Delhi 110029, India *Corresponding author. Tel.: þ91 9810350650.
E-mail address: [email protected] (P. Mathur) Accepted 13 December 2014 http://dx.doi.org/10.1016/j.jinf.2014.12.004 ª 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserved.
Rhodococcus equi infection in a patient with Crohn’s disease treated with infliximab
Dear Editor, Loulerque et al., in this Journal recently reported a large prospective survey of bacteremias in patients on TNF immunomodulators.1 We encountered a patient with bacteremia due to Rhodococcus equi while receiving treatment with infliximab. A 41-year-old man was admitted to the hospital because of fever up to 40 C, cough, and malaise during the last week. A diagnostic of Crohn’s disease had been made seventeen years earlier and the patient had been treated with infliximab every other month in the last three years, during which he had suffered no flare-up of the disease. At the time of admission to the hospital the white-cell count was 27,180 per cubic millimetre (neutrophils 84%, lymphocytes 8%, monocytes 8%) and the serum creatinine level was 125 mmol per litre. Arterial blood gas measurements while the patient was breathing ambient air revealed a partial pressure of oxygen of 55.2 mm Hg and a partial pressure of carbon dioxide of 33.0 mm Hg, with a pH of 7.51. Results of an HIV screening test were negative. A chest radiograph revealed a pulmonary consolidation in the right upper lobe and the right lower lobe, with minimal right pleural effusion. Two sets of blood cultures became positive for mucoid Gram-positive cocobacillary rods. After 48 h of incubation, rieux, France) identified the the API Coryne system (BioMe organism as R. equi. The patient was treated with
vancomycin and rifampin. Vancomycin was replaced by meropenem due to an allergic reaction to vancomycin. The clinical response was favourable, with abatement of fever and respiratory symptoms two weeks after the initiation of therapy. Three weeks later, the patient was switched to the combination of oral clarithromycin and rifampin. This treatment was continued for five months, until the normalization of the chest radiograph. Treatment with infliximab was restarted. The patient has remained asymptomatic for the next four years. The introduction of biological agents, such as infliximab, acting against tumour necrosis factor-a (TNF-a) was a major advance for the treatment of an increasing number of chronic diseases. The use of infliximab has greatly improved the treatment of Crohn’s disease, reducing the rate of complications, hospitalizations and surgical procedures. TNF-a plays an important role in cellular immunity, The clinical use of TNF antagonists can increase the risk of infections caused by intracellular microorganisms, including Mycobacterium tuberculosis, nontuberculous mycobacteria, Aspergillus species, Histoplama capsulatum, Candida species, Listeria, Cryptococcus neoformans, Nocardia species, Salmonella species, Staphylococcus aureus, Pseudomonas aeruginosa, Toxoplasma gondii, Brucella species, Bartonella species, Pneumocystis jirovecci, Leishmania donovani, Coccidiodes immitis, Mycobacterium leprae and cytomegalovirus.1e3 Until now, Rhodococcus equi has not been included among the opportunistic microorganisms causing infections in patients treated with TNF-a inhibitors.1e3 A PubMed search using the MeSH terms infliximab, tumour necrosis factor-alpha, biologic therapy and Rhodococcus equi revealed no cases of R. equi infection in patients treated with infliximab. R. equi is a Gram-positive pleomorphic coccobacillus. It is a facultative intracellular pathogen that can survive inside macrophages, producing a necrotizing granulomatous reaction.4,5 R equi primarily causes zoonotic infection in grazing animals, mainly horses and foals. Human infections are rather uncommon. They usually occur in persons with diminished cellular immunity, especially those with AIDS.4 It is amazing the lack of reports about R. equi infection in patients receiving infliximab, since it is well known that TNF plays a major role in innate immune response to R. equi.6 Based on our observation, we suggest that R. equi should be included among the microorganisms that can cause opportunistic infections in patients receiving infliximab.
Conflicts of interest None.
References 1. Loulergue P, Tubach F, Salmon D, Dellamonica P, Taillan B, Thorel JB, et al. Bacteremia in patients receiving TNF-alpha antagonistsda prospective multicenter study. J Infect 2013; 67:524e8. http://dx.doi.org/10.1016/j.jinf.2013.07.027. 2. Wallis RS, Broder MS, Wong JY, Hanson ME, Beenhouwer DO. Granulomatous infectious diseases associated with tumor necrosis factor antagonists. Clin Infect Dis 2004;38:1261e5.
687
heterotypic G9P[4] rotavirus strain in Mexico. J Infect Dis 2011;204:783e6. 10. Anderson EJ, Reddy S, Katz BZ, Noskin GA. Indirect protection and indirect measures of protection from rotavirus in adults. J Infect Dis 2012;205:1762e4. author reply 4e5.
Evan J. Anderson* Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States Deanna B. Shippee Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Jacqueline E. Tate Center for Disease Control and Prevention (CDC), Atlanta, GA, United States Bruce Larkin Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Melissa D. Bregger Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Ben Z. Katz Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Gary A. Noskin Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States Bethany K. Sederdahl Andi L. Shane Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States Umesh D. Parashar Center for Disease Control and Prevention (CDC), Atlanta, GA, United States Ram Yogev Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States *Corresponding author. Division of Pediatric Infectious Diseases, 2015 Uppergate, Atlanta, GA 30323, United States. Tel.: þ1 (404) 727 1746; fax: þ1 (404) 727 9223.
E-mail address: [email protected] Accepted 28 November 2014 http://dx.doi.org/10.1016/j.jinf.2014.11.012 ª 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserved.
Aeromonas spp as a causative agent for nosocomial infection in trauma patients
Dear Sir, We read with great interest the review by Parker and Shaw1 highlighting the importance of Aeromonas spp in the causation of human intestinal and extra-intestinal infections. Most of the published reports suggest causation of Aeromonas extra-intestinal infection in immunosuppressed patients or infections after contact with water contaminated with Aeromonas. A retrospective analysis of the clinical and microbiological characteristics of all the Aeromonas strains isolated over a period of seven years (2007e2014) was performed at a 165 bedded, level-1 trauma center of India. To the best of our knowledge no studies have yet been conducted on trauma patients from India or worldover.1e7 All patients who were culture positive for Aeromonas spp were identified from the hospital’s computerized database and their medical records were reviewed. All isolates were identified by Vitek 2 automated system (Biomerieux; France) and antimicrobial susceptibility was performed using the disk diffusion method and by the Vitek 2 AST card. During the study period, a total 78 samples grew Aeromonas on culture, which were obtained from 36 patients. Aeromonas hydrophilla 60(77%) was the most common strain followed by Aeromonas caviae 12(15%); Aeromonas sobria 4(5%) and Aeromonas veronii & Aeromonas salmonicida one strain each (1%). Pus and wound swab 57(73%) were the most common source of Aeromonas spp followed by blood 12(15%) and drain fluid 7(9%). Twenty six(46%) samples of pus and wound swab grew Aeromonas spp as a co-infection with other pathogens. The most common co-pathogen was Pseudomonas aeruginosa 10(13%) followed by Enterobacter spp 8(10%) and Klebsiella pneumonia 7(9%). Acinetobacter baumannii grew as a copathogen in 1(1%) sample. Detailed antimicrobial susceptibility of all the isolates is given in Table 1. Maximum susceptibility was seen to the third generation cephalosporins group of drugs i.e. ceftazidime 44(56.4%), ceftriaxone 44(56.4%) and ceftriaxone/sulbactam 44(56.4%). Twelve (15.4%) patients developed Aeromonas bacteremia secondary to wound infection. Of these, two (5.5%) developed septic shock and died due the same. One (2.7%) patient had trauma at multiple sites at the time of presentation and died of cardiorespiratory arrest due to severe head injury. Two (5.5%) patients developed pneumonia with Aeromonas as the causative pathogen. One (2.7%) of them died due to Acute Respiratory Distress Syndrome. Thus, the total in-hospital mortality was 4(11%). Detailed clinical characteristics of all the patients is described in Table 2. Apart from ours, there is only one case series reported from India by Mukhopadhyay et al.8 in which only eight cases of extraintestinal infections due to Aeromonas have been reported. We found that A. hydrophila was the
688 Table 1 isolates.
Letters to the Editor Antimicrobial susceptibility of the Aeromonas
Antimicrobial agent
Drug resistance (number; percentage)
Ampicillin Chloramphenicol Cefepime Ciprofloxacin Ceftazidime Ceftriaxone Cefotaxime Cefoxitin Gentamicin Imipenem Levofloxacin Meropenem Piperacillin Piperacillin-tazobactam Tigecycline Colistin Cefoperazone-sulbactam Cotrimoxazole Netilmicin Cefepime-tazobactam Ceftriaxone-sulbactam Ticarcillin-clavulanate
22; 14; 28; 36; 44; 44; 38; 72; 24; 6; 28; 10; 36; 32; 10; 32; 40; 52; 8; 12; 44; 42;
28.2 17.9 35.9 2.6 56.4 56.4 48.7 92.3 30.7 7.7 35.9 12.8 46.2 41 12.8 41.02 51.28 66.67 10.26 15.38 56.4 53.8
most common species of aeromonad causing nosocomial infection in trauma patients of our hospital. The results of our study are in collaboration with the results of studies from other parts of the world.1e7
Table 2 Clinical characteristics of patients with Aeromonas infection. Patient characteristic
Number; percentage (n Z 36)
Age; Mean (years); SD Sex (male) ICU admission Initial presentation Necrotizing fasciitis Osteomyelitis Myonecrosis Shock Laboratory findings (mean SD) White blood cell (cells/mL) Aspartate transaminase (IU/L) Total bilirubin (mg/dL) Serum creatinine (mg/dL) Body temperature C (median) range Average length of stay mean; SD (days) Time to culture negativity mean; SD (days) In hospital Mortality Mechanical ventilation
23; 10.99 25; 69.44 8; 22.22 12; 33.33 10; 27.78 6; 16.67 2; 5.55 10,257.4 4808.5 40.2 60.9 1.7 1.5 1.5 1.0 39.8 (37.7e41.8) 62; 35 15; 9 4; 11.1 13; 36.1
Our study, however, disproved the findings of the earlier studies where Aeromonas infection was associated with immunosupression1 as the patient population getting admitted after trauma are representative of healthy population. Our findings suggest that aeromonads can cause skin and soft tissue infections irrespective of the patient’s immune status. In contrast to other studies,1 none of the patients in our study had a history of exposure to aqueous environment prior to infection. However, being a retrospective study, the complete details of all patients could not be retrieved which may be a cause of the discrepancy. A total of 22 (61%) of the patients with SSTI had coinfection, which is consistent with the results of the previous studies.9 However, in contrast to the previous reports, Pseudomonas aeruginosa was the most common copathogen in our study. Thus, the clinicians treating patients with Aeromonas spp should be aware of copathogens and give broad spectrum antibiotics to cover both pathogens. It was difficult to assess the contribution of each organism in patients with co-infection as the mortality rate was low. This study had few limitations. First, the Vitek 2 GN system for Aeromonas species identification might not be accurate enough to identify the isolates to the species level. The accuracy of this commercial system for correct identification is less than 90% at the species level.10 The isolates were also not available for further molecular studies. We did not retest the in vitro susceptibilities of the isolates by the microdilution methods. Most importantly, we could not compare the clinical differences between patients with monomicrobial SSTIs due to Aeromonas species and patients with polymicrobial infections. In conclusion, Aeromonas species are important pathogens causing SSTIs. Most of the infections during the study period were polymicrobial. Empirical antibiotics for patients with Aeromonas infection should be broadspectrum to cover dual infections. No financial support has been obtained for conducting the above study and there is no conflict of interest between the co-authors.
References 1. Parker JL, Shaw JG. Aeromonas spp. clinical microbiology and disease. J Infect 2011;62:109e18. 2. Duthie R, Ling TW, Cheng AF, French GL. Aeromonas septicaemia in Hong Kong species distribution and associated diseases. J Infect 1995;30:241e4. 3. Janda JM, Guthertz LS, Kokka RP, Shimada T. Aeromonas species in septicemia: laboratory characteristics and clinical observations. Clin Infect Dis 1994;19:77e83. 4. Ko WC, Chuang YC. Aeromonas bacteremia: review of 59 episodes. Clin Infect Dis 1995;20:1298e304. 5. Dryden M, Munro R. Aeromonas septicemia: relationship of species and clinical features. Pathology 1989;21:111e4. 6. Hochedez P, Hope-Rapp E, Olive C, Nicolas M, Beaucaure G, A. Bacteremia caused by Aeromonas species [corrected] Cabie complex in the Caribbean Islands of Martinique and Guadeloupe. Am J Trop Med Hyg 2010;83:1123e7. 7. Lay CJ, Zhuang HJ, Ho YH, Tsai YS, Wang LS, Tsai CC. Different clinical characteristics between polymicrobial and monomicrobial Aeromonas bacteremiada study of 216 cases. Intern Med 2010;49:2415e21.
Letters to the Editor
689
8. Mukhopadhyay C, Chawla K, Sharma Y, Bairy I. Emerging extraintestinal infections with Aeromonas hydrophila in coastal region of southern Karnataka. J Postgrad Med 2008;54(3): 199e202. 9. Janda JM, Abbott SL. The genus Aeromonas: taxonomy, pathogenicity, and infection. Clin Microbiol Rev 2010;23:35e73. 10. Ling TK, Tam PC, Liu ZK, Cheng AF. Evaluation of VITEK 2 rapid identification and susceptibility testing system against gramnegative clinical isolates. J Clin Microbiol 2001;39:2964e6.
Priyam Batra Purva Mathur* M.C. Misra All India Institute of Medical Sciences, New Delhi 110029, India *Corresponding author. Tel.: þ91 9810350650.
E-mail address: [email protected] (P. Mathur) Accepted 13 December 2014 http://dx.doi.org/10.1016/j.jinf.2014.12.004 ª 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserved.
Rhodococcus equi infection in a patient with Crohn’s disease treated with infliximab
Dear Editor, Loulerque et al., in this Journal recently reported a large prospective survey of bacteremias in patients on TNF immunomodulators.1 We encountered a patient with bacteremia due to Rhodococcus equi while receiving treatment with infliximab. A 41-year-old man was admitted to the hospital because of fever up to 40 C, cough, and malaise during the last week. A diagnostic of Crohn’s disease had been made seventeen years earlier and the patient had been treated with infliximab every other month in the last three years, during which he had suffered no flare-up of the disease. At the time of admission to the hospital the white-cell count was 27,180 per cubic millimetre (neutrophils 84%, lymphocytes 8%, monocytes 8%) and the serum creatinine level was 125 mmol per litre. Arterial blood gas measurements while the patient was breathing ambient air revealed a partial pressure of oxygen of 55.2 mm Hg and a partial pressure of carbon dioxide of 33.0 mm Hg, with a pH of 7.51. Results of an HIV screening test were negative. A chest radiograph revealed a pulmonary consolidation in the right upper lobe and the right lower lobe, with minimal right pleural effusion. Two sets of blood cultures became positive for mucoid Gram-positive cocobacillary rods. After 48 h of incubation, rieux, France) identified the the API Coryne system (BioMe organism as R. equi. The patient was treated with
vancomycin and rifampin. Vancomycin was replaced by meropenem due to an allergic reaction to vancomycin. The clinical response was favourable, with abatement of fever and respiratory symptoms two weeks after the initiation of therapy. Three weeks later, the patient was switched to the combination of oral clarithromycin and rifampin. This treatment was continued for five months, until the normalization of the chest radiograph. Treatment with infliximab was restarted. The patient has remained asymptomatic for the next four years. The introduction of biological agents, such as infliximab, acting against tumour necrosis factor-a (TNF-a) was a major advance for the treatment of an increasing number of chronic diseases. The use of infliximab has greatly improved the treatment of Crohn’s disease, reducing the rate of complications, hospitalizations and surgical procedures. TNF-a plays an important role in cellular immunity, The clinical use of TNF antagonists can increase the risk of infections caused by intracellular microorganisms, including Mycobacterium tuberculosis, nontuberculous mycobacteria, Aspergillus species, Histoplama capsulatum, Candida species, Listeria, Cryptococcus neoformans, Nocardia species, Salmonella species, Staphylococcus aureus, Pseudomonas aeruginosa, Toxoplasma gondii, Brucella species, Bartonella species, Pneumocystis jirovecci, Leishmania donovani, Coccidiodes immitis, Mycobacterium leprae and cytomegalovirus.1e3 Until now, Rhodococcus equi has not been included among the opportunistic microorganisms causing infections in patients treated with TNF-a inhibitors.1e3 A PubMed search using the MeSH terms infliximab, tumour necrosis factor-alpha, biologic therapy and Rhodococcus equi revealed no cases of R. equi infection in patients treated with infliximab. R. equi is a Gram-positive pleomorphic coccobacillus. It is a facultative intracellular pathogen that can survive inside macrophages, producing a necrotizing granulomatous reaction.4,5 R equi primarily causes zoonotic infection in grazing animals, mainly horses and foals. Human infections are rather uncommon. They usually occur in persons with diminished cellular immunity, especially those with AIDS.4 It is amazing the lack of reports about R. equi infection in patients receiving infliximab, since it is well known that TNF plays a major role in innate immune response to R. equi.6 Based on our observation, we suggest that R. equi should be included among the microorganisms that can cause opportunistic infections in patients receiving infliximab.
Conflicts of interest None.
References 1. Loulergue P, Tubach F, Salmon D, Dellamonica P, Taillan B, Thorel JB, et al. Bacteremia in patients receiving TNF-alpha antagonistsda prospective multicenter study. J Infect 2013; 67:524e8. http://dx.doi.org/10.1016/j.jinf.2013.07.027. 2. Wallis RS, Broder MS, Wong JY, Hanson ME, Beenhouwer DO. Granulomatous infectious diseases associated with tumor necrosis factor antagonists. Clin Infect Dis 2004;38:1261e5.