- Email: [email protected]
Potential virulence factors of Candida spp. isolated from clinical and food sources
240
Letters to the Editor / Journal of Hospital Infection 75 (2010) 236–246
Funding source None. References 1. Yong D, Toleman MA, Giske CG, et al. Characterization of a new metallo-betalactamase gene, bla(NDM-1), and a novel erythromycin esterase gene carried on a unique genetic structure in Klebsiella pneumoniae sequence type 14 from India. Antimicrob Agents Chemother 2009;53:5046–5054. 2. Health Protection Agency. Carbapenemase-producing Enterobacteriaceae in the UK: NDM (New Delhi Metallo-b-lacatamase: repeated importation from Indian subcontinent. National Resistance Alert 3 ADDENDUM. London: HPA; 2009. 3. Health Protection Agency. Carbapenemase-producing Enterobacteriaceae in the UK: multi-faceted emergence. Resistance Alert 3. London: HPA; 2009. 4. Patel G, Huprikar S, Factor SH, Jenkins SG, Calfee DP. Outcomes of carbapenemresistant Klebsiella pneumoniae infection and the impact of antimicrobial and adjunctive therapies. Infect Control Hosp Epidemiol 2008;29:1099–1106. 5. Department of Health and Human Services and Centers for Disease Control and Prevention. Guidance for control of infections with carbapenem-resistant or carbapenemase-producing Enterobacteriaceae in acute care facilities. Morb Mortal Wkly Rep 2009;58:256–260. 6. Centers for Disease Control and Prevention. Laboratory protocol for detection of carbapenem-resistant or carbapenemase-producing, Klebsiella spp. and E. coli from rectal swabs. Atlanta: CDC; 2009. 7. Bhattacharya S, Price N, Boxall E, et al. Holiday haemodialysis and imported hepatitis C virus infection: a series of sixteen cases in two large haemodialysis units. J Clin Virol 2009;45:296–299.
A. Muir* M.J. Weinbren University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK * Corresponding author. Address: Pathology Department, 4th Floor, West Wing, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, CV2 2DX, UK. Tel.: þ44 2476 965455; fax: þ44 2476 965441. E-mail address: [email protected] (A. Muir) Available online 01 May 2010 Ó 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.02.005
Potential virulence factors of Candida spp. isolated from clinical and food sources Madam, Nosocomial infections caused by Candida spp. have become commoner in recent years, and those caused by non-albicans Candida (NAC) species are rising proportionally more than Candida albicans, being responsible for 35–65% of all candidaemias in the general patient population.1,2 It is difficult to determine the source of these once-unusual yeasts, since most are normally present in the environment and may, in some cases, may be part of human microflora. It has also been considered that food or drinks may be sources of Candida spp., which may, following ingestion, enter the bloodstream and cause fungaemia.3 Although the cases reported are rare and occur in unusual clinical situations, it is possible that the presence of yeasts in foods may be of some clinical significance. In order to colonise, infect and evade host defence mechanisms, C. albicans possesses many virulence factors, including the ability to produce and secrete enzymes: protease, phospholipase and haemolysin.4 Yet these determinants of pathogenicity are poorly described in NAC species and particularly in non-clinical Candida spp. isolates.
In this study we aimed to compare the phospholipase, protease and haemolytic activities in a total of 47 Candida spp. isolates obtained from clinical (urine, sputum and blood) and food (fruit, water, honey, fruit juice) sources. C. albicans ATCC 18804 (which produces proteases, phospholipases and haemolysin) was included as a control strain. Evaluations of enzymatic activities were made by plate assays with different test media. Enzymatic activities were scored according to Pz value determined by the ratio of the colony diameter to the total colony plus precipitation/degradation halo.5 Phospholipase production was determined on egg-yolk medium.5 Phospholipases are enzymes which have been implicated in the pathogenicity of opportunistic yeasts by degrading cell membranes.4 Phospholipase activity was found in 94% of the isolates tested. No significant difference (P < 0.05) was observed between the two groups of isolates. The Pz values of the Candida spp. isolates ranged from 0.24 to 1 for the food group and from 0.36 to 1 for the clinical isolates. Interestingly, the highest phospholipase activity was observed in the food isolates of C. magnoliae, followed by Candida humicola and Candida colliculosa, yeasts not commonly associated with human disease. Recently, a case of fungaemia caused by Candida magnoliae was reported.3 The authors hypothesised that the patient may have consumed products such as yoghurt, cheese, or honey which contain yeasts such as C. magnoliae that, in view of his clinical condition, may have entered the bloodstream. Our results support the authors’ suggestion that C. magnoliae probably should be added to the long list of yeasts capable of causing bloodstream infections in immunocompromised or critically ill patients. Protease production was determined according to the method of Aoki et al.6 Proteases act as virulence factors by contributing to hosttissue invasion by digesting proteins such as haemoglobin and keratin.4 In this study we found higher protease activity in yeasts of food origin. The Pz values of the Candida spp. isolates ranged from 0.45 to 1, for the food group, and from 0.50 to 1 for the clinical isolates, with mean values of 0.78 and 0.90, respectively. Again, we detected very high protease activity in all C. magnoliae isolates and in the majority of the C. parapsilosis of food origin. None and/or very low protease activity was observed in Candida lusitaniae, Candida krusei, Candida glabrata and Candida guillermondii isolates. Despite the fact that 95% of Candida bloodstream infections are due to four species, C. albicans, C. glabrata, C. parapsilosis and Candida tropicalis, only a few studies have been conducted to evaluate haemolytic activity of Candida spp.7,8 Here, haemolytic activity, evaluated using the method described by Luo et al., was found in 69% of the isolates tested.8 No significant differences (P < 0.05) were observed between the isolates of the two origins. All C. magnoliae and C. guillermondii isolates, irrespective of their origin, failed to demonstrate any haemolytic activity, whereas C. parapsilosis isolates demonstrated differing abilities to produce haemolysin. The remaining isolates displayed very high haemolytic activities, with two isolates of C. albicans the highest. In recent years, there has been an increasing awareness of NAC species as important opportunistic pathogens. Here we report phospholipase, protease, and haemolytic activity in clinical and food Candida spp. isolates. Despite the low number of isolates tested, our results suggest that food Candida spp. strains could pose a risk as they possess virulence factors that would enable them to cause infections. We conclude that further studies are needed to investigate these virulence determinants in Candida spp. from food origin and their putative effects in the human host. Conflict of interest statement None declared. Funding sources None.
Letters to the Editor / Journal of Hospital Infection 75 (2010) 236–246
References 1. Galán-Ladero MA, Blanco MT, Sacristán B, Fernandéz-Calderón C, PérezGiraldo C, Gomez-Garcia AC. Enzymatic activities of Candida tropicalis isolated from hospitalized patients. Med Mycol 2009;9:1–4. 2. Krcmery V, Barnes AJ. Non-albicans Candida spp. causing fungaemia: pathogenicity and antifungal resistance. J Hosp Infect 2002;50:243–260. 3. Cascio GL, Dalle Carbonare L, Maccacaro L, et al. First case of bloodstream infection due to Candida magnoliae in a Chinese oncological patient. J Clin Microbiol 2007;45:3470–3473. 4. van Burik JH, Magee PT. Aspects of fungal pathogenesis in humans. Annu Rev Microbiol 2001;55:743–772. 5. Price MF, Wilkinson ID, Gentry LO. Plate method for detection of phospholipase activity in Candida albicans. Sabouraudia 1982;20:7–14. 6. Aoki S, Ito-Kuwa S, Nakamura Y, Masuhara T. Comparative pathogenicity of a wild-type strain and respiratory mutants of Candida albicans in mice. Zentralbl Bakteriol 1984;273:332–343. 7. Pfaller MA, Diekema DJ. Role of sentinel surveillance of candidemia: trends in species distribution and antifungal susceptibility. J Clin Microbiol 2002;40: 3551–3557. 8. Luo G, Samaranayake LP, Yau JYY. Candida species exhibit differential in vitro hemolytic activities. J Clin Microbiol 2001;39:2971–2974.
E. Costaa,b A. Inêsa A. Mendes-Faiaa M.J. Saavedrab A. Mendes-Ferreiraa,* a Institute for Biotechnology and Bioengineering (IBB/CGB-UTAD), School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal b
*
CECAV-UTAD, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal Corresponding author. Address: Institute for Biotechnology and Bioengineering (IBB/CGB-UTAD), School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, P.O. Box 1013, 5001-801 Vila Real, Portugal. Tel.: þ351 259350550; fax: þ351 259350480. E-mail address: [email protected] (A. Mendes-Ferreira) Available online 31 March 2010
Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.03.001
Nosocomial transmission of Salmonella typhimurium in renal transplant recipients Madam, We report a cluster of Salmonella typhimurium phage type DT193 in renal transplant patients linked to an asymptomatic carrier. Salmonella spp. can establish chronic asymptomatic infection in the gallbladder. Gallstones are an important risk factor for developing carriage which may be facilitated by bile-induced biofilm formation on the gallstone. A high correlation has been reported to exist between individuals who have gallstones and those who become chronic carriers.1 A limited study reported that chronic carriage of S. typhimurium is mediated by the same mechanism.2 Nosocomial transmission of S. typhimurium can be secondary to a foodborne source or person-to-person transmission. Of the latter, cases can usually be traced to an admission of an index case with diarrhoea.3 Our experience suggests that cross-infection can occur from an asymptomatic carrier.
241
The index case was a man with asymptomatic cholelithiasis. He had been known to the nephrology team with end-stage renal failure and was initially managed with continuous ambulatory peritoneal dialysis. The patient had proven S. typhimurium DT193 gastroenteritis in July 2008 from which he had made an uneventful recovery. However, three months later, S. typhimurium DT193 was isolated from seroma fluid and wound swabs from an incisional hernia that had developed following removal of his peritoneal dialysis catheter. He went on to have a renal transplant in April 2009. During his recovery, S. typhimurium DT193 was isolated from a blood culture and also from his postoperative wound drain fluid secondary to a urinary leak. He did not have diarrhoea. Two patients on the ward developed diarrhoea over a 10 day period. Isolates from stool specimens of these patients were confirmed as S. typhimurium DT193. The organism was also isolated from the faeces of a third patient who had one episode of diarrhoea. Temporal and spatial relationships between all four patients were examined by reviewing case-notes and liaising with ward staff. An outbreak investigation team visited the ward to identify possible risk factors. It is routine practice to educate able patients to manage their own drains including emptying of drain-bags at their respective bed-spaces. The nursing staff would then empty the drain fluid in the sluice on the adjacent ward. We were informed by the nursing staff that the index patient was friendly and sociable, visiting other patients and he had also been known to share food that his family brought in for him. It is difficult to monitor inpatient movement and to restrict movement if there are no symptoms of diarrhoea. Infection control measures need to be carefully observed. Patient and staff education is paramount to ensure strict compliance with barrier precautions. En-suite facilities were not available on the ward and therefore all shared facilities, including the day-room, should be frequently cleaned. Convalescent excretion of Salmonella is common following infection. However, persistent excretion (and transmission) beyond one year occurred in fewer than 1% of subjects.4 Therefore, follow-up faecal cultures after Salmonella infections are usually unnecessary. Following the index case's gastroenteritis in 2008, it would not have been routine practice to look for chronic carriage. It is of interest to note that during the recent admission of the index case, we had isolated an organism which we designated Serratia sp. based on its appearance on selective agar from urine and wound swabs prior to the positive blood culture. In retrospect, this was almost certainly Salmonella sp. This serves as a reminder to be vigilant of previous positive culture results in high risk patients who may be chronic carriers. This would certainly have altered clinical management as considerations would have been made for cholecystectomy prior to renal transplant, or strict isolation would have been instituted. All the contacts were treated with a course of ciprofloxacin for their acute diarrhoeal illness and made an uneventful recovery. The index patient was deemed a poor candidate for further surgery or consideration of cholecystectomy and has indeed declined surgery. Acknowledgement We thank the Laboratory of Enteric Pathogens at the Centre for Infections, Health Protection Agency Colindale, London for serotyping the isolates. Conflict of interest statement None declared. Funding sources None.
Letters to the Editor / Journal of Hospital Infection 75 (2010) 236–246
Funding source None. References 1. Yong D, Toleman MA, Giske CG, et al. Characterization of a new metallo-betalactamase gene, bla(NDM-1), and a novel erythromycin esterase gene carried on a unique genetic structure in Klebsiella pneumoniae sequence type 14 from India. Antimicrob Agents Chemother 2009;53:5046–5054. 2. Health Protection Agency. Carbapenemase-producing Enterobacteriaceae in the UK: NDM (New Delhi Metallo-b-lacatamase: repeated importation from Indian subcontinent. National Resistance Alert 3 ADDENDUM. London: HPA; 2009. 3. Health Protection Agency. Carbapenemase-producing Enterobacteriaceae in the UK: multi-faceted emergence. Resistance Alert 3. London: HPA; 2009. 4. Patel G, Huprikar S, Factor SH, Jenkins SG, Calfee DP. Outcomes of carbapenemresistant Klebsiella pneumoniae infection and the impact of antimicrobial and adjunctive therapies. Infect Control Hosp Epidemiol 2008;29:1099–1106. 5. Department of Health and Human Services and Centers for Disease Control and Prevention. Guidance for control of infections with carbapenem-resistant or carbapenemase-producing Enterobacteriaceae in acute care facilities. Morb Mortal Wkly Rep 2009;58:256–260. 6. Centers for Disease Control and Prevention. Laboratory protocol for detection of carbapenem-resistant or carbapenemase-producing, Klebsiella spp. and E. coli from rectal swabs. Atlanta: CDC; 2009. 7. Bhattacharya S, Price N, Boxall E, et al. Holiday haemodialysis and imported hepatitis C virus infection: a series of sixteen cases in two large haemodialysis units. J Clin Virol 2009;45:296–299.
A. Muir* M.J. Weinbren University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK * Corresponding author. Address: Pathology Department, 4th Floor, West Wing, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, CV2 2DX, UK. Tel.: þ44 2476 965455; fax: þ44 2476 965441. E-mail address: [email protected] (A. Muir) Available online 01 May 2010 Ó 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.02.005
Potential virulence factors of Candida spp. isolated from clinical and food sources Madam, Nosocomial infections caused by Candida spp. have become commoner in recent years, and those caused by non-albicans Candida (NAC) species are rising proportionally more than Candida albicans, being responsible for 35–65% of all candidaemias in the general patient population.1,2 It is difficult to determine the source of these once-unusual yeasts, since most are normally present in the environment and may, in some cases, may be part of human microflora. It has also been considered that food or drinks may be sources of Candida spp., which may, following ingestion, enter the bloodstream and cause fungaemia.3 Although the cases reported are rare and occur in unusual clinical situations, it is possible that the presence of yeasts in foods may be of some clinical significance. In order to colonise, infect and evade host defence mechanisms, C. albicans possesses many virulence factors, including the ability to produce and secrete enzymes: protease, phospholipase and haemolysin.4 Yet these determinants of pathogenicity are poorly described in NAC species and particularly in non-clinical Candida spp. isolates.
In this study we aimed to compare the phospholipase, protease and haemolytic activities in a total of 47 Candida spp. isolates obtained from clinical (urine, sputum and blood) and food (fruit, water, honey, fruit juice) sources. C. albicans ATCC 18804 (which produces proteases, phospholipases and haemolysin) was included as a control strain. Evaluations of enzymatic activities were made by plate assays with different test media. Enzymatic activities were scored according to Pz value determined by the ratio of the colony diameter to the total colony plus precipitation/degradation halo.5 Phospholipase production was determined on egg-yolk medium.5 Phospholipases are enzymes which have been implicated in the pathogenicity of opportunistic yeasts by degrading cell membranes.4 Phospholipase activity was found in 94% of the isolates tested. No significant difference (P < 0.05) was observed between the two groups of isolates. The Pz values of the Candida spp. isolates ranged from 0.24 to 1 for the food group and from 0.36 to 1 for the clinical isolates. Interestingly, the highest phospholipase activity was observed in the food isolates of C. magnoliae, followed by Candida humicola and Candida colliculosa, yeasts not commonly associated with human disease. Recently, a case of fungaemia caused by Candida magnoliae was reported.3 The authors hypothesised that the patient may have consumed products such as yoghurt, cheese, or honey which contain yeasts such as C. magnoliae that, in view of his clinical condition, may have entered the bloodstream. Our results support the authors’ suggestion that C. magnoliae probably should be added to the long list of yeasts capable of causing bloodstream infections in immunocompromised or critically ill patients. Protease production was determined according to the method of Aoki et al.6 Proteases act as virulence factors by contributing to hosttissue invasion by digesting proteins such as haemoglobin and keratin.4 In this study we found higher protease activity in yeasts of food origin. The Pz values of the Candida spp. isolates ranged from 0.45 to 1, for the food group, and from 0.50 to 1 for the clinical isolates, with mean values of 0.78 and 0.90, respectively. Again, we detected very high protease activity in all C. magnoliae isolates and in the majority of the C. parapsilosis of food origin. None and/or very low protease activity was observed in Candida lusitaniae, Candida krusei, Candida glabrata and Candida guillermondii isolates. Despite the fact that 95% of Candida bloodstream infections are due to four species, C. albicans, C. glabrata, C. parapsilosis and Candida tropicalis, only a few studies have been conducted to evaluate haemolytic activity of Candida spp.7,8 Here, haemolytic activity, evaluated using the method described by Luo et al., was found in 69% of the isolates tested.8 No significant differences (P < 0.05) were observed between the isolates of the two origins. All C. magnoliae and C. guillermondii isolates, irrespective of their origin, failed to demonstrate any haemolytic activity, whereas C. parapsilosis isolates demonstrated differing abilities to produce haemolysin. The remaining isolates displayed very high haemolytic activities, with two isolates of C. albicans the highest. In recent years, there has been an increasing awareness of NAC species as important opportunistic pathogens. Here we report phospholipase, protease, and haemolytic activity in clinical and food Candida spp. isolates. Despite the low number of isolates tested, our results suggest that food Candida spp. strains could pose a risk as they possess virulence factors that would enable them to cause infections. We conclude that further studies are needed to investigate these virulence determinants in Candida spp. from food origin and their putative effects in the human host. Conflict of interest statement None declared. Funding sources None.
Letters to the Editor / Journal of Hospital Infection 75 (2010) 236–246
References 1. Galán-Ladero MA, Blanco MT, Sacristán B, Fernandéz-Calderón C, PérezGiraldo C, Gomez-Garcia AC. Enzymatic activities of Candida tropicalis isolated from hospitalized patients. Med Mycol 2009;9:1–4. 2. Krcmery V, Barnes AJ. Non-albicans Candida spp. causing fungaemia: pathogenicity and antifungal resistance. J Hosp Infect 2002;50:243–260. 3. Cascio GL, Dalle Carbonare L, Maccacaro L, et al. First case of bloodstream infection due to Candida magnoliae in a Chinese oncological patient. J Clin Microbiol 2007;45:3470–3473. 4. van Burik JH, Magee PT. Aspects of fungal pathogenesis in humans. Annu Rev Microbiol 2001;55:743–772. 5. Price MF, Wilkinson ID, Gentry LO. Plate method for detection of phospholipase activity in Candida albicans. Sabouraudia 1982;20:7–14. 6. Aoki S, Ito-Kuwa S, Nakamura Y, Masuhara T. Comparative pathogenicity of a wild-type strain and respiratory mutants of Candida albicans in mice. Zentralbl Bakteriol 1984;273:332–343. 7. Pfaller MA, Diekema DJ. Role of sentinel surveillance of candidemia: trends in species distribution and antifungal susceptibility. J Clin Microbiol 2002;40: 3551–3557. 8. Luo G, Samaranayake LP, Yau JYY. Candida species exhibit differential in vitro hemolytic activities. J Clin Microbiol 2001;39:2971–2974.
E. Costaa,b A. Inêsa A. Mendes-Faiaa M.J. Saavedrab A. Mendes-Ferreiraa,* a Institute for Biotechnology and Bioengineering (IBB/CGB-UTAD), School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal b
*
CECAV-UTAD, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal Corresponding author. Address: Institute for Biotechnology and Bioengineering (IBB/CGB-UTAD), School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, P.O. Box 1013, 5001-801 Vila Real, Portugal. Tel.: þ351 259350550; fax: þ351 259350480. E-mail address: [email protected] (A. Mendes-Ferreira) Available online 31 March 2010
Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.03.001
Nosocomial transmission of Salmonella typhimurium in renal transplant recipients Madam, We report a cluster of Salmonella typhimurium phage type DT193 in renal transplant patients linked to an asymptomatic carrier. Salmonella spp. can establish chronic asymptomatic infection in the gallbladder. Gallstones are an important risk factor for developing carriage which may be facilitated by bile-induced biofilm formation on the gallstone. A high correlation has been reported to exist between individuals who have gallstones and those who become chronic carriers.1 A limited study reported that chronic carriage of S. typhimurium is mediated by the same mechanism.2 Nosocomial transmission of S. typhimurium can be secondary to a foodborne source or person-to-person transmission. Of the latter, cases can usually be traced to an admission of an index case with diarrhoea.3 Our experience suggests that cross-infection can occur from an asymptomatic carrier.
241
The index case was a man with asymptomatic cholelithiasis. He had been known to the nephrology team with end-stage renal failure and was initially managed with continuous ambulatory peritoneal dialysis. The patient had proven S. typhimurium DT193 gastroenteritis in July 2008 from which he had made an uneventful recovery. However, three months later, S. typhimurium DT193 was isolated from seroma fluid and wound swabs from an incisional hernia that had developed following removal of his peritoneal dialysis catheter. He went on to have a renal transplant in April 2009. During his recovery, S. typhimurium DT193 was isolated from a blood culture and also from his postoperative wound drain fluid secondary to a urinary leak. He did not have diarrhoea. Two patients on the ward developed diarrhoea over a 10 day period. Isolates from stool specimens of these patients were confirmed as S. typhimurium DT193. The organism was also isolated from the faeces of a third patient who had one episode of diarrhoea. Temporal and spatial relationships between all four patients were examined by reviewing case-notes and liaising with ward staff. An outbreak investigation team visited the ward to identify possible risk factors. It is routine practice to educate able patients to manage their own drains including emptying of drain-bags at their respective bed-spaces. The nursing staff would then empty the drain fluid in the sluice on the adjacent ward. We were informed by the nursing staff that the index patient was friendly and sociable, visiting other patients and he had also been known to share food that his family brought in for him. It is difficult to monitor inpatient movement and to restrict movement if there are no symptoms of diarrhoea. Infection control measures need to be carefully observed. Patient and staff education is paramount to ensure strict compliance with barrier precautions. En-suite facilities were not available on the ward and therefore all shared facilities, including the day-room, should be frequently cleaned. Convalescent excretion of Salmonella is common following infection. However, persistent excretion (and transmission) beyond one year occurred in fewer than 1% of subjects.4 Therefore, follow-up faecal cultures after Salmonella infections are usually unnecessary. Following the index case's gastroenteritis in 2008, it would not have been routine practice to look for chronic carriage. It is of interest to note that during the recent admission of the index case, we had isolated an organism which we designated Serratia sp. based on its appearance on selective agar from urine and wound swabs prior to the positive blood culture. In retrospect, this was almost certainly Salmonella sp. This serves as a reminder to be vigilant of previous positive culture results in high risk patients who may be chronic carriers. This would certainly have altered clinical management as considerations would have been made for cholecystectomy prior to renal transplant, or strict isolation would have been instituted. All the contacts were treated with a course of ciprofloxacin for their acute diarrhoeal illness and made an uneventful recovery. The index patient was deemed a poor candidate for further surgery or consideration of cholecystectomy and has indeed declined surgery. Acknowledgement We thank the Laboratory of Enteric Pathogens at the Centre for Infections, Health Protection Agency Colindale, London for serotyping the isolates. Conflict of interest statement None declared. Funding sources None.