Journal of Infection (I99O) zo, I5I-I54
CASE R E P O R T S Detective
work in continuous
ambulatory
peritoneal
W. A l - W a l i , R. B a i l l o d , J. M. T. H a m i l t o n - M i l l e r
dialysis
a n d W. B r u m f i t t
Departments of Medical Microbiology and Renal Dialysis Unit, The Royal Free Hospital and School of Medicine, Pond Street, Hampstead, London NW3 2QG U.K. Accepted for publication 31 October I989 Summary We report five cases of continuous ambulatory peritoneal dialysis in which the mechanisms and sources of infection were established. We show how diligent enquiry and environmental investigation can explain the pathogenesis of infection and help in prevention by motivation of the patient. Introduction Bacterial peritonitis is still the most important complication of continuous ambulatory peritoneal dialysis (CAPD). 1 Coagulase-negative staphylococci, mainly Staphylococcus epidermidis, are the organisms most frequently recovered and it is assumed that these come from the colonising skin flora. Clinical experience suggests that the most common reason for infection is a mistake on the part of the patient, most often by failing to keep to the instructions concerning aseptic techniques during the dialysis bag exchanges. T h e same may apply to S. aureus peritonitis where the source is again the colonising flora in anterior nares, throat, axilla, perineum, fingers, skin lesions, ulcers, etc. T h e source of other organisms remains largely unknown and the precise routes by which bacteria reach the peritoneal cavity have not been fully investigated. Continuous surveillance of CAPD patients should provide answers to the problem and such knowledge could be used to reduce the incidence of these infections. In our Renal Dialysis Unit we have observed some unusual organisms causing CAPD peritonitis, and in the five cases reported here we have been able to trace the source, and thus explain the events leading to the peritoneal infection. During the time this investigation was being carried out, patients were being treated with an antibiotic regimen consisting of one compound with activity only against Gram-positive bacteria (vancomycin or teicoplanin) combined with an agent active against Gram-negative organisms only (aztreonam). When the infecting bacterium was identified and its sensitivity known, the inappropriate antibiotic was stopped, making mono-therapy possible.
Case reports Case x A 52-year-old woman who had been on CAPD for IO months presented to our unit with severe abdominal pain, vomiting, and rigors. Her dialysis effluent °I63-4453/9o/o2oI5~ +o4
$o2.oo/o
© I99O The British Society for the Study of Infection
15 2
w. AL-WALI
ET AL.
was cloudy and contained 38oo white blood cells/#l (95 % polymorphonuclear leucocytes). No bacteria were seen on microscopic examination of the centrifuged deposit. Intraperitoneal aztreonam and vancomycin were given to cover both Gram-negative and Gram-positive infections. Aerobic Gramnegative rods, subsequently identified as Aeromonas caviae, were isolated after 48 h from peritoneal dialysis fluid inoculated into blood culture bottles. Since the organism was sensitive to aztreonam and not to vancomycin, the former was given alone for a further 19 days and the patient made an uneventful recovery. This unusual infecting organism prompted us to investigate the source. T h e patient admitted that while preparing for dialysis just before she developed peritonitis, she had sprayed the catheter connector site from a bottle that had previously contained an alcohol based disinfectant (Frekaderm) but which had subsequently been used as a container to spray a houseplant (Tillandsia ionantha, an airplant) with water. Aeromonas caviae was isolated from the inner tube of the spray and from the houseplant, but not from the water-tap used to fill the bottle, or from the water inside the container. Culture of the patient's faeces did not yield the organism. This case has been reported in detail elsewhere. ~ Case 2
A 67-year old man who had been on CAPD for 3 years came to the renal dialysis unit complaining of severe abdominal pain, nausea, and lethargy. His CAPD exchange bag was cloudy and microscopical examination of the dialysis effluent demonstrated a white cell count of 854o cells/#l, 75 % of which were polymorphonuclear leucocytes, IO% lymphocytes and the remainder degenerated cells. T h e specimen was cultured using the Bactec NR65o system which showed a positive signal after 24 h. Gram stain of the Bactec culture specimen demonstrated Gram-positive rods which were subsequently identified as Bacillus cereus. On the basis of the clinical and microbiological findings a diagnosis of bacterial peritonitis was made. T h e patient was treated with intraperitoneal teicoplanin and aztreonam initially, but following identification of the organism and demonstration that it was sensitive to teicoplanin and resistant to aztreonam, treatment was continued with teicoplanin alone for a total period of 21 days. T h e patient recovered clinically within 48 h. In view of the rarity of the infecting organism, we investigated the source of the infection. On close questioning the patient admitted that he did not wash his hands after preparing a 'roll-up' cigarette just before exchanging his dialysis bag. Bacteriological culture of the batch of tobacco used to prepare the cigarette yielded four different morphological types of aerobic spore-bearing bacilli, one of which was speciated as B. cereus. This isolate was subsequently shown to be of the same serotype (H29) as the infecting organism. Case 3
A 56-year-old man who had been on CAPD for 7 months presented to our Unit with abdominal pain only. T h e cloudy peritoneal dialysis effluent contained 85oo white blood cells//zl, of which 9o % were polymorphonuclear
CAPD peritonitis
I53
leucocytes. No bacteria were seen on microscopic examination of the Gramstained centrifuged deposit. Since the identity of the organism was unknown, treatment was started with intraperitoneal aztreonam and vancomycin. After 4days, Gram-positive cocci, subsequently identified as Staphylococcus haemolyticus, were cultured from dialysis effluent which had been inoculated into blood culture bottles. T h e organism was sensitive to vancomycin but not to aztreonam. T r e a t m e n t was continued for a further 17 days with intraperitoneal vancomycin alone. On questioning, the patient said that the day prior to this infection he was 'sanding' the walls of a room in his house using an electric sanding machine. This work caused him to be covered with plaster dust. An impression culture made of the 'sander disc' which he had used, yielded six morphological types of coagulase-negative staphylococci. One of these had the same API profile and antibiotic sensitivity pattern as the infecting organism. Plasmid electrophoresis showed absence of plasmids from the environmental and infecting strains, supporting the view that the strains were identical. This patient, unlike Case 2 had always been meticulous in his exchange technique and clearly did not realise that plaster dust could be a microbiological hazard. Case 4
A 7o-year-old man who had been on CAPD for 2 years came to the Renal Dialysis Unit complaining of sudden abdominal pain and vomiting with no fever. T h e dialysis effluent contained c. Iooo white cells/#1, of which 9o % were polymorphonuclear leucocytes. Gram-negative rods were seen on direct microscopical examination of the Gram-stained deposit. T h e organism was sensitive to aztreonam and responded to intraperitoneal treatment with this agent. Initially there was a clinical suspicion of acute cholecystitis because of the right-sided abdominal pain and tenderness which had not been present in the three previous episodes of peritonitis in this patient. This was not however, supported by ultra-sound examination of the gall bladder or liver function tests. A swab from the Tenckhoff catheter exit site, a rectal swab and the peritoneal dialysis effluent all grew a strain of Escherichia coli of serotype oi9. No organisms were isolated from his fingers. We conclude that the patient had contaminated his peritoneal dialysis exit site with faecal organisms which then caused the peritonitis. Case 5 A 69-year-old man who had been on CAPD for 2~1 years presented to the renal dialysis unit with mild malaise and cloudiness of his dialysis effluent which contained c. Iooo white blood cells/#1 (98 % polymorphonuclear leucocytes). Bacteria were not seen in a Gram stain of the centrifuged deposit. He was started on intraperitoneal vancomycin and aztreonam. After 48 h Grampositive cocci were isolated from the dialysis fluid and these were subsequently identified as Streptococcus salivarius. T h e organism was sensitive to vancomycin but not to aztreonam: vancomycin alone was continued and the patient recovered. T h e patient had suffered from an upper respiratory infection 3 days before
154
W. A L - W A L I E T A L .
the onset of his peritonitis. During the night before he came to hospital he had sneezed while exchanging bags. In view of the history and nature of the infecting organism, we suspected that the infection came from his oral cavity which is the natural habitat of S. salivarius. Swabs taken from his mouth and throat 2 days later did not yield the same organism; however it might have been eliminated by the vancomycin therapy. Patients are encouraged to report episodes which might contaminate the dialysis apparatus. However, this patient was known to be careless in changing his ' lines' and on previous occasions his apparatus had been noted to be dirty. Discussion
It is our practice to encourage patients who have made a mistake during bag exchange (such as dropping a line onto the floor) to report immediately to the Renal Dialysis Unit where they receive prophylactic antibiotic treatment. T h e patients described above either did not realise a mistake had been made (Cases I, 3 and 4) or had chosen to ignore their mistake (Cases 2 and 5). It appears from the cases described that when 'mistakes' are made by patients during dialysis exchanges, infecting organisms might not be those most commonly incriminated in causing peritonitis, especially S. epidermidis. Little is known about the origin of infecting organisms other than skin flora, although the tap water supply has been suggested as a possible source, a Epidemiological investigation of the source and mode of infection has proved to be worthwhile and satisfying when dealing with these unusual infections. Such information enables specific counselling of the patients to be carried out. In particular we impress u p o n them the need to take great care when carrying out procedures that involve breaking the catheter 'line' while exchanging dialysis fluid bags. Counselling also enables them to appreciate the wide variety of potential microbiological hazards that they may encounter in their homes. T h e fourth case demonstrated how microbiological tracing of the source of infection can help by excluding a diagnosis and establishing an alternative. It is hoped that our experience may help others to reduce the incidence of infection in CAPD. References
I. Spencer RC. Infections in continuous ambulatory peritoneal dialysis. J Med Microbiol I988 ; 27: I-9. 2. A1-Wali W, Baillod R, Hamilton-Miller J M T , Brumfitt W. Houseplant peritonitis. Lancet
1988; ii: 957. 3. Scott E, BloomfieldSF, Barlow CG. An investigation into microbial contaminationin the home. J Hyg 1982; 89: 279-293.
CASE R E P O R T S Detective
work in continuous
ambulatory
peritoneal
W. A l - W a l i , R. B a i l l o d , J. M. T. H a m i l t o n - M i l l e r
dialysis
a n d W. B r u m f i t t
Departments of Medical Microbiology and Renal Dialysis Unit, The Royal Free Hospital and School of Medicine, Pond Street, Hampstead, London NW3 2QG U.K. Accepted for publication 31 October I989 Summary We report five cases of continuous ambulatory peritoneal dialysis in which the mechanisms and sources of infection were established. We show how diligent enquiry and environmental investigation can explain the pathogenesis of infection and help in prevention by motivation of the patient. Introduction Bacterial peritonitis is still the most important complication of continuous ambulatory peritoneal dialysis (CAPD). 1 Coagulase-negative staphylococci, mainly Staphylococcus epidermidis, are the organisms most frequently recovered and it is assumed that these come from the colonising skin flora. Clinical experience suggests that the most common reason for infection is a mistake on the part of the patient, most often by failing to keep to the instructions concerning aseptic techniques during the dialysis bag exchanges. T h e same may apply to S. aureus peritonitis where the source is again the colonising flora in anterior nares, throat, axilla, perineum, fingers, skin lesions, ulcers, etc. T h e source of other organisms remains largely unknown and the precise routes by which bacteria reach the peritoneal cavity have not been fully investigated. Continuous surveillance of CAPD patients should provide answers to the problem and such knowledge could be used to reduce the incidence of these infections. In our Renal Dialysis Unit we have observed some unusual organisms causing CAPD peritonitis, and in the five cases reported here we have been able to trace the source, and thus explain the events leading to the peritoneal infection. During the time this investigation was being carried out, patients were being treated with an antibiotic regimen consisting of one compound with activity only against Gram-positive bacteria (vancomycin or teicoplanin) combined with an agent active against Gram-negative organisms only (aztreonam). When the infecting bacterium was identified and its sensitivity known, the inappropriate antibiotic was stopped, making mono-therapy possible.
Case reports Case x A 52-year-old woman who had been on CAPD for IO months presented to our unit with severe abdominal pain, vomiting, and rigors. Her dialysis effluent °I63-4453/9o/o2oI5~ +o4
$o2.oo/o
© I99O The British Society for the Study of Infection
15 2
w. AL-WALI
ET AL.
was cloudy and contained 38oo white blood cells/#l (95 % polymorphonuclear leucocytes). No bacteria were seen on microscopic examination of the centrifuged deposit. Intraperitoneal aztreonam and vancomycin were given to cover both Gram-negative and Gram-positive infections. Aerobic Gramnegative rods, subsequently identified as Aeromonas caviae, were isolated after 48 h from peritoneal dialysis fluid inoculated into blood culture bottles. Since the organism was sensitive to aztreonam and not to vancomycin, the former was given alone for a further 19 days and the patient made an uneventful recovery. This unusual infecting organism prompted us to investigate the source. T h e patient admitted that while preparing for dialysis just before she developed peritonitis, she had sprayed the catheter connector site from a bottle that had previously contained an alcohol based disinfectant (Frekaderm) but which had subsequently been used as a container to spray a houseplant (Tillandsia ionantha, an airplant) with water. Aeromonas caviae was isolated from the inner tube of the spray and from the houseplant, but not from the water-tap used to fill the bottle, or from the water inside the container. Culture of the patient's faeces did not yield the organism. This case has been reported in detail elsewhere. ~ Case 2
A 67-year old man who had been on CAPD for 3 years came to the renal dialysis unit complaining of severe abdominal pain, nausea, and lethargy. His CAPD exchange bag was cloudy and microscopical examination of the dialysis effluent demonstrated a white cell count of 854o cells/#l, 75 % of which were polymorphonuclear leucocytes, IO% lymphocytes and the remainder degenerated cells. T h e specimen was cultured using the Bactec NR65o system which showed a positive signal after 24 h. Gram stain of the Bactec culture specimen demonstrated Gram-positive rods which were subsequently identified as Bacillus cereus. On the basis of the clinical and microbiological findings a diagnosis of bacterial peritonitis was made. T h e patient was treated with intraperitoneal teicoplanin and aztreonam initially, but following identification of the organism and demonstration that it was sensitive to teicoplanin and resistant to aztreonam, treatment was continued with teicoplanin alone for a total period of 21 days. T h e patient recovered clinically within 48 h. In view of the rarity of the infecting organism, we investigated the source of the infection. On close questioning the patient admitted that he did not wash his hands after preparing a 'roll-up' cigarette just before exchanging his dialysis bag. Bacteriological culture of the batch of tobacco used to prepare the cigarette yielded four different morphological types of aerobic spore-bearing bacilli, one of which was speciated as B. cereus. This isolate was subsequently shown to be of the same serotype (H29) as the infecting organism. Case 3
A 56-year-old man who had been on CAPD for 7 months presented to our Unit with abdominal pain only. T h e cloudy peritoneal dialysis effluent contained 85oo white blood cells//zl, of which 9o % were polymorphonuclear
CAPD peritonitis
I53
leucocytes. No bacteria were seen on microscopic examination of the Gramstained centrifuged deposit. Since the identity of the organism was unknown, treatment was started with intraperitoneal aztreonam and vancomycin. After 4days, Gram-positive cocci, subsequently identified as Staphylococcus haemolyticus, were cultured from dialysis effluent which had been inoculated into blood culture bottles. T h e organism was sensitive to vancomycin but not to aztreonam. T r e a t m e n t was continued for a further 17 days with intraperitoneal vancomycin alone. On questioning, the patient said that the day prior to this infection he was 'sanding' the walls of a room in his house using an electric sanding machine. This work caused him to be covered with plaster dust. An impression culture made of the 'sander disc' which he had used, yielded six morphological types of coagulase-negative staphylococci. One of these had the same API profile and antibiotic sensitivity pattern as the infecting organism. Plasmid electrophoresis showed absence of plasmids from the environmental and infecting strains, supporting the view that the strains were identical. This patient, unlike Case 2 had always been meticulous in his exchange technique and clearly did not realise that plaster dust could be a microbiological hazard. Case 4
A 7o-year-old man who had been on CAPD for 2 years came to the Renal Dialysis Unit complaining of sudden abdominal pain and vomiting with no fever. T h e dialysis effluent contained c. Iooo white cells/#1, of which 9o % were polymorphonuclear leucocytes. Gram-negative rods were seen on direct microscopical examination of the Gram-stained deposit. T h e organism was sensitive to aztreonam and responded to intraperitoneal treatment with this agent. Initially there was a clinical suspicion of acute cholecystitis because of the right-sided abdominal pain and tenderness which had not been present in the three previous episodes of peritonitis in this patient. This was not however, supported by ultra-sound examination of the gall bladder or liver function tests. A swab from the Tenckhoff catheter exit site, a rectal swab and the peritoneal dialysis effluent all grew a strain of Escherichia coli of serotype oi9. No organisms were isolated from his fingers. We conclude that the patient had contaminated his peritoneal dialysis exit site with faecal organisms which then caused the peritonitis. Case 5 A 69-year-old man who had been on CAPD for 2~1 years presented to the renal dialysis unit with mild malaise and cloudiness of his dialysis effluent which contained c. Iooo white blood cells/#1 (98 % polymorphonuclear leucocytes). Bacteria were not seen in a Gram stain of the centrifuged deposit. He was started on intraperitoneal vancomycin and aztreonam. After 48 h Grampositive cocci were isolated from the dialysis fluid and these were subsequently identified as Streptococcus salivarius. T h e organism was sensitive to vancomycin but not to aztreonam: vancomycin alone was continued and the patient recovered. T h e patient had suffered from an upper respiratory infection 3 days before
154
W. A L - W A L I E T A L .
the onset of his peritonitis. During the night before he came to hospital he had sneezed while exchanging bags. In view of the history and nature of the infecting organism, we suspected that the infection came from his oral cavity which is the natural habitat of S. salivarius. Swabs taken from his mouth and throat 2 days later did not yield the same organism; however it might have been eliminated by the vancomycin therapy. Patients are encouraged to report episodes which might contaminate the dialysis apparatus. However, this patient was known to be careless in changing his ' lines' and on previous occasions his apparatus had been noted to be dirty. Discussion
It is our practice to encourage patients who have made a mistake during bag exchange (such as dropping a line onto the floor) to report immediately to the Renal Dialysis Unit where they receive prophylactic antibiotic treatment. T h e patients described above either did not realise a mistake had been made (Cases I, 3 and 4) or had chosen to ignore their mistake (Cases 2 and 5). It appears from the cases described that when 'mistakes' are made by patients during dialysis exchanges, infecting organisms might not be those most commonly incriminated in causing peritonitis, especially S. epidermidis. Little is known about the origin of infecting organisms other than skin flora, although the tap water supply has been suggested as a possible source, a Epidemiological investigation of the source and mode of infection has proved to be worthwhile and satisfying when dealing with these unusual infections. Such information enables specific counselling of the patients to be carried out. In particular we impress u p o n them the need to take great care when carrying out procedures that involve breaking the catheter 'line' while exchanging dialysis fluid bags. Counselling also enables them to appreciate the wide variety of potential microbiological hazards that they may encounter in their homes. T h e fourth case demonstrated how microbiological tracing of the source of infection can help by excluding a diagnosis and establishing an alternative. It is hoped that our experience may help others to reduce the incidence of infection in CAPD. References
I. Spencer RC. Infections in continuous ambulatory peritoneal dialysis. J Med Microbiol I988 ; 27: I-9. 2. A1-Wali W, Baillod R, Hamilton-Miller J M T , Brumfitt W. Houseplant peritonitis. Lancet
1988; ii: 957. 3. Scott E, BloomfieldSF, Barlow CG. An investigation into microbial contaminationin the home. J Hyg 1982; 89: 279-293.
