Journal of Infection (i99i) 23, 179-182
CASE REPORT Septicaemia caused by Pediococcus pentosaceus: a new opportunistic pathogen G. D. Corcoran,* N. Gibbons and T. E. Mulvihill
Department of Microbiology, St James's Hospital, Dublin 8, Republic of Ireland Accepted for publication 28 January 1991 Summary A case of septicaemia caused by Pediococcuspentosaceus is described. The role played by pediococci, and other vancomycin-resistant Gram-positive cocci, in disease states is examined. We suggest that in immunocompromised patients these organisms act as opportunist pathogens. This would appear to be the first reported case of P. pentosaceus septicaemia.
Introduction Pediococci are homofermentative lactic acid bacteria which are vancomycin resistant, normally associated with food sources. 1 H u m a n isolates have been described but, with the exception of one isolate of Pediococcus acidilaetici, were of doubtful pathological significance.2 We report the isolation of Pediococcus pentosaceus from the blood cultures of a severely immunocompromised patient, and review the possible role of this, and other, vancomycin-resistant Gram-positive cocci as pathogens.
Case report A 57-year-old woman was admitted with severe pancreatitis, complicated by paralytic ileus and diabetic ketoacidosis. On day 5, total colectomy and partial small bowel resection was carried out, as gangrene of the colon and distal small intestine was noted at laparotomy. Surgery was again required on day I5 for oversewing of a bleeding gastric ulcer. T h e patient's course was further complicated by many septic episodes, including isolation of Candida glabrata, Streptococcus faecalis and Hansenula anomala from blood cultures, and Pseudomonas aeruginosa from sputum, on separate occasions. All of these episodes responded to appropriate antimicrobial chemotherapy, which included prolonged courses of amphotericin B, vancomycin, ceftazidime and amikacin. Vancomycin was recommended on day 8o, when Streptococcus faecium was isolated from peripheral and central blood cultures. Initially the patient settled * Address correspondence to: D r G . D . Corcoran, University College Hospital, Gower Street, London W C I E 6AU, U.K. oi63-4453/9I/O5OI79+o4 $03.00/0
© I99I The British Society for the Study of Infection
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but on day 9I, while still on vancomycin, she developed a persistent pyrexia (up to 39"8 °C), and a fall in blood pressure was noted, with elevation of the peripheral white cell count from 7"4× lO9/1-13"9 × lO9/1. A vancomycinresistant Gram-positive coccus was isolated from blood cultures on two occasions 48 h apart, and was identified as P. pentosaceus using the tests and procedures outlined by Facklam et al. 3 Vancomycin sensitivity testing was carried out using a modified Stokes technique on Columbia blood agar with a 30 #g vancomycin disc. T h e isolate was sensitive to ampicillin and cefuroxime while resistant to penicillin as well as vancomycin. Our findings were subsequently confirmed by the Central Public Health Laboratory, Colindale, London, and the strain was accepted as N C T C strain 12274. Ampicillin was commenced promptly at the time of primary isolation of the, then, unidentified vancomycin-resistant organism, because of the patient's clinical condition. She initially responded, and recovered from this episode. However, further complications including the development of a left-sided subphrenic abscess (from which P. aeruginosa was isolated) led to a deterioration in her condition and she died on day 135 of her hospital admission. Discussion
Vancomycin-resistant Gram-positive cocci (Enterococcus spp., Leuconostoc spp. and Pediococcus spp.) are increasingly seen as having pathogenic potential) '5 Such resistance in enterococci is well-described and hospital outbreaks due to these organisms have occurred. 6'7 T h e mechanism of vancomycin resistance in enterococci is not fully elucidated. 5 Factors such as prolonged hospitalisation and immunosuppression, especially with concurrent antibiotic therapy (but not necessarily with vancomycin), have been stressed as important in acquisition of these infections. 5'8 Leuconostoc species have been isolated in similar circumstances from immunocompromised patients and meningitis has also been described with Leuconostoc species. 9 Pediococci are homofermentative lactic acid producing Gram-positive cocci, which are facultatively anaerobic and catalase-negative. T h e mechanism of resistance to vancomycin is unknown but it appears to be almost universal among pediococci, and in a clinical laboratory, is the first critical step in their identification.2.3 Previously regarded as harmless organisms, they are found in dairy products and on plants, and have many uses in food technology. 1 H u m a n isolates have been rare but are described from saliva, TM and more recently from faeces, where their role was unclear. 4 Other isolates from clinical sources have been described, but were always regarded to be of doubtful pathological significance. T h e case for a pathogenic role for pediococci was strengthened when nine cases of bacteraemia with vancomycin-resistant Pediococcus acidilactici were reported in severely compromised patients, eight of whom were febrile, s While the organism may have been pathogenic in at least some of these cases, no firm conclusions were possible. Pediococcus acidilactici, while shown by D N A homology to be a distinct species, is, none the less, closely related to P. pentosaceus in aldolase studies and differs biochemically from it mainly in its failure to ferment maltose, n More recently a case of septicaemia
Septicaemia caused by P. pentosaceus
ISI
due to P. acidilactici in a patient with acute myeloblastic leukaemia was described. 2 T h e r e does not appear to be a reported case of sepsis due to P. pentosaceus. We believe that P. pentosaceus was a very likely opportunistic p a t h o g e n in our patient. Systemic features such as pyrexia, h y p o t e n s i o n and elevation of the peripheral white cell count suggest that this m a y have been the case. Certainly the patient was highly i m m u n o c o m p r o m i s e d and had had multiple courses of antibiotics (including vancomycin on two occasions). At no time was the isolate, initially tentatively identified as a vancomycin-resistant Streptococcus spp., considered clinically to be a c o n t a m i n a n t and high dose ampicillin therapy was p r o m p t l y instituted. F u r t h e r m o r e , the excellent clinical response to ampicillin suggests that P. pentosaceus was likely to have been the cause of the septic episode as all previous bacteriological isolates (including enterococcal isolates) were ampicillin resistant. T h e question of the role of v a n c o m y c i n in the selection of vancomycinresistant organisms, such as pediococci, in susceptible patients, is an obvious one. It is not accepted by some authors that this role is critical, s but others feel that the increasing use of v a n c o m y c i n contributes to the development of such resistance? '6 It is certainly a factor which cannot be ignored in this case, but the role o f other antibiotics (e.g. t h i r d generation cephalosporins) also needs to be questioned. T h e source of the organism in our patient is unclear. However, n o r m a l diet was r e s u m e d before the septicaemic episode, as the patient's condition improved. T h u s , a dietary source is possible as dairy products f o r m e d a major part o f her diet at this stage. T h e isolation of a vancomycin-resistant Gram-positive coccus from a clinical specimen should lead to a full clinical review of the patient and f u r t h e r identification o f the organism i n v o l v e d ? T h e probable pathogenic potential of P. pentosaceus and other pediococci in i m m u n o c o m p r o m i s e d patients should be recognised. (We gratefully acknowledge the assistance of Professor C. T. Keane, Department of Microbiology, St James's Hospital, for editorial advice. The patient secretarial help of Mrs M. Foody was invaluable, as always.) References
I. Colman G, Efstratiou A. Vancomycin-resistant leuconostocs, lactobacilli and now pediococci, ff Hosp Infect 1987; IO : 1-3. 2. Golledge CL, Stingemore N, Aravena M, Joske D. Septicaernia caused by vancomycinresistant Pediococcus acidilactici. J Clin Microbiol 199o; 28: 1678-1679. 3- Facklam R, Hollis D, Collins MD. Identification of Gram-positive coccal and coccobacillary vancomycin-resistant bacteria. J Clin Microbiol 1989; 27: 724-73o. 4. Ruoff KL, Kuritzkes DR, Wolfson JS, Ferraro MJ. Vancomycin-resistant Gram-positive bacteria isolated from human sources. J Clin Microbiol I988; 26: 2064-2068. 5. Greenwood D. Antibiotic resistance in enterococci. J Antimicrob Chemother 1989; 24: 631-635. 6. Johnson AP, Uttley AHC, Woodford N, George RC. Resistance to vancomycin and teicoplanin: an emerging clinical problem. Clin Microbiol Reviews 199o; 3: 28o--291. 7. Uttley AHC, Collins CH, Naidoo J, George RC. Vancomycin-resistant enterococci. Lancet (Letter) 1988; i: 57-58. 8. Mastro TD, Spika JS, Lozano P, Appel J, Facklam RR. Vancomycin-resistant Pediococcus acidilactici: nine cases of bacteraemia. J Infect Dis 199o; I6I: 956-960.
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9. Coovadia YM, Solwa Z, van den Ende J. Meningitis caused by vancomycin-resistant Leuconostoc sp. J Clin Microbiol 1987: 25: I784-I785. IO. Sims W. The isolation of pediococci from human saliva. Arch Oral Biol 1966; I I : 967-972. IX. Garvie EI. Genus Pediococcus. In: Sneath PHA, Mair NS, Sharp ME, Holt JG, Eds. Bergey's manual of systematic bacteriology, i st ed. Baltimore: Williams and Wilkins, I986; lO75-1o79.
CASE REPORT Septicaemia caused by Pediococcus pentosaceus: a new opportunistic pathogen G. D. Corcoran,* N. Gibbons and T. E. Mulvihill
Department of Microbiology, St James's Hospital, Dublin 8, Republic of Ireland Accepted for publication 28 January 1991 Summary A case of septicaemia caused by Pediococcuspentosaceus is described. The role played by pediococci, and other vancomycin-resistant Gram-positive cocci, in disease states is examined. We suggest that in immunocompromised patients these organisms act as opportunist pathogens. This would appear to be the first reported case of P. pentosaceus septicaemia.
Introduction Pediococci are homofermentative lactic acid bacteria which are vancomycin resistant, normally associated with food sources. 1 H u m a n isolates have been described but, with the exception of one isolate of Pediococcus acidilaetici, were of doubtful pathological significance.2 We report the isolation of Pediococcus pentosaceus from the blood cultures of a severely immunocompromised patient, and review the possible role of this, and other, vancomycin-resistant Gram-positive cocci as pathogens.
Case report A 57-year-old woman was admitted with severe pancreatitis, complicated by paralytic ileus and diabetic ketoacidosis. On day 5, total colectomy and partial small bowel resection was carried out, as gangrene of the colon and distal small intestine was noted at laparotomy. Surgery was again required on day I5 for oversewing of a bleeding gastric ulcer. T h e patient's course was further complicated by many septic episodes, including isolation of Candida glabrata, Streptococcus faecalis and Hansenula anomala from blood cultures, and Pseudomonas aeruginosa from sputum, on separate occasions. All of these episodes responded to appropriate antimicrobial chemotherapy, which included prolonged courses of amphotericin B, vancomycin, ceftazidime and amikacin. Vancomycin was recommended on day 8o, when Streptococcus faecium was isolated from peripheral and central blood cultures. Initially the patient settled * Address correspondence to: D r G . D . Corcoran, University College Hospital, Gower Street, London W C I E 6AU, U.K. oi63-4453/9I/O5OI79+o4 $03.00/0
© I99I The British Society for the Study of Infection
I80
G.D. CORCORAN ET AL.
but on day 9I, while still on vancomycin, she developed a persistent pyrexia (up to 39"8 °C), and a fall in blood pressure was noted, with elevation of the peripheral white cell count from 7"4× lO9/1-13"9 × lO9/1. A vancomycinresistant Gram-positive coccus was isolated from blood cultures on two occasions 48 h apart, and was identified as P. pentosaceus using the tests and procedures outlined by Facklam et al. 3 Vancomycin sensitivity testing was carried out using a modified Stokes technique on Columbia blood agar with a 30 #g vancomycin disc. T h e isolate was sensitive to ampicillin and cefuroxime while resistant to penicillin as well as vancomycin. Our findings were subsequently confirmed by the Central Public Health Laboratory, Colindale, London, and the strain was accepted as N C T C strain 12274. Ampicillin was commenced promptly at the time of primary isolation of the, then, unidentified vancomycin-resistant organism, because of the patient's clinical condition. She initially responded, and recovered from this episode. However, further complications including the development of a left-sided subphrenic abscess (from which P. aeruginosa was isolated) led to a deterioration in her condition and she died on day 135 of her hospital admission. Discussion
Vancomycin-resistant Gram-positive cocci (Enterococcus spp., Leuconostoc spp. and Pediococcus spp.) are increasingly seen as having pathogenic potential) '5 Such resistance in enterococci is well-described and hospital outbreaks due to these organisms have occurred. 6'7 T h e mechanism of vancomycin resistance in enterococci is not fully elucidated. 5 Factors such as prolonged hospitalisation and immunosuppression, especially with concurrent antibiotic therapy (but not necessarily with vancomycin), have been stressed as important in acquisition of these infections. 5'8 Leuconostoc species have been isolated in similar circumstances from immunocompromised patients and meningitis has also been described with Leuconostoc species. 9 Pediococci are homofermentative lactic acid producing Gram-positive cocci, which are facultatively anaerobic and catalase-negative. T h e mechanism of resistance to vancomycin is unknown but it appears to be almost universal among pediococci, and in a clinical laboratory, is the first critical step in their identification.2.3 Previously regarded as harmless organisms, they are found in dairy products and on plants, and have many uses in food technology. 1 H u m a n isolates have been rare but are described from saliva, TM and more recently from faeces, where their role was unclear. 4 Other isolates from clinical sources have been described, but were always regarded to be of doubtful pathological significance. T h e case for a pathogenic role for pediococci was strengthened when nine cases of bacteraemia with vancomycin-resistant Pediococcus acidilactici were reported in severely compromised patients, eight of whom were febrile, s While the organism may have been pathogenic in at least some of these cases, no firm conclusions were possible. Pediococcus acidilactici, while shown by D N A homology to be a distinct species, is, none the less, closely related to P. pentosaceus in aldolase studies and differs biochemically from it mainly in its failure to ferment maltose, n More recently a case of septicaemia
Septicaemia caused by P. pentosaceus
ISI
due to P. acidilactici in a patient with acute myeloblastic leukaemia was described. 2 T h e r e does not appear to be a reported case of sepsis due to P. pentosaceus. We believe that P. pentosaceus was a very likely opportunistic p a t h o g e n in our patient. Systemic features such as pyrexia, h y p o t e n s i o n and elevation of the peripheral white cell count suggest that this m a y have been the case. Certainly the patient was highly i m m u n o c o m p r o m i s e d and had had multiple courses of antibiotics (including vancomycin on two occasions). At no time was the isolate, initially tentatively identified as a vancomycin-resistant Streptococcus spp., considered clinically to be a c o n t a m i n a n t and high dose ampicillin therapy was p r o m p t l y instituted. F u r t h e r m o r e , the excellent clinical response to ampicillin suggests that P. pentosaceus was likely to have been the cause of the septic episode as all previous bacteriological isolates (including enterococcal isolates) were ampicillin resistant. T h e question of the role of v a n c o m y c i n in the selection of vancomycinresistant organisms, such as pediococci, in susceptible patients, is an obvious one. It is not accepted by some authors that this role is critical, s but others feel that the increasing use of v a n c o m y c i n contributes to the development of such resistance? '6 It is certainly a factor which cannot be ignored in this case, but the role o f other antibiotics (e.g. t h i r d generation cephalosporins) also needs to be questioned. T h e source of the organism in our patient is unclear. However, n o r m a l diet was r e s u m e d before the septicaemic episode, as the patient's condition improved. T h u s , a dietary source is possible as dairy products f o r m e d a major part o f her diet at this stage. T h e isolation of a vancomycin-resistant Gram-positive coccus from a clinical specimen should lead to a full clinical review of the patient and f u r t h e r identification o f the organism i n v o l v e d ? T h e probable pathogenic potential of P. pentosaceus and other pediococci in i m m u n o c o m p r o m i s e d patients should be recognised. (We gratefully acknowledge the assistance of Professor C. T. Keane, Department of Microbiology, St James's Hospital, for editorial advice. The patient secretarial help of Mrs M. Foody was invaluable, as always.) References
I. Colman G, Efstratiou A. Vancomycin-resistant leuconostocs, lactobacilli and now pediococci, ff Hosp Infect 1987; IO : 1-3. 2. Golledge CL, Stingemore N, Aravena M, Joske D. Septicaernia caused by vancomycinresistant Pediococcus acidilactici. J Clin Microbiol 199o; 28: 1678-1679. 3- Facklam R, Hollis D, Collins MD. Identification of Gram-positive coccal and coccobacillary vancomycin-resistant bacteria. J Clin Microbiol 1989; 27: 724-73o. 4. Ruoff KL, Kuritzkes DR, Wolfson JS, Ferraro MJ. Vancomycin-resistant Gram-positive bacteria isolated from human sources. J Clin Microbiol I988; 26: 2064-2068. 5. Greenwood D. Antibiotic resistance in enterococci. J Antimicrob Chemother 1989; 24: 631-635. 6. Johnson AP, Uttley AHC, Woodford N, George RC. Resistance to vancomycin and teicoplanin: an emerging clinical problem. Clin Microbiol Reviews 199o; 3: 28o--291. 7. Uttley AHC, Collins CH, Naidoo J, George RC. Vancomycin-resistant enterococci. Lancet (Letter) 1988; i: 57-58. 8. Mastro TD, Spika JS, Lozano P, Appel J, Facklam RR. Vancomycin-resistant Pediococcus acidilactici: nine cases of bacteraemia. J Infect Dis 199o; I6I: 956-960.
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9. Coovadia YM, Solwa Z, van den Ende J. Meningitis caused by vancomycin-resistant Leuconostoc sp. J Clin Microbiol 1987: 25: I784-I785. IO. Sims W. The isolation of pediococci from human saliva. Arch Oral Biol 1966; I I : 967-972. IX. Garvie EI. Genus Pediococcus. In: Sneath PHA, Mair NS, Sharp ME, Holt JG, Eds. Bergey's manual of systematic bacteriology, i st ed. Baltimore: Williams and Wilkins, I986; lO75-1o79.
