To the Editor,
Achromobacter (alcaligenes) xylosoxidans (AX) is a gram-negative, aerobic bacillus, carried by animals (rabbits, ferrets), although it is also present in normal human flora, especially of the skin and gastrointestinal tract1.
It is an opportunistic bacterium with low virulence, except in immunocompromised patients, in whom it can cause serious infections such as meningitis, endocarditis and, most commonly, bacteraemia2.
Patients with a catheter are more likely to develop AX and it is more frequent in peritoneal dialysis (PD) than haemodialysis (HD) patients, where there are few published cases; all cases are associated with a central venous catheter (CVC)3-5. Contamination of the catheter, the heparin multi-dose vials, the antiseptic solutions and the dialysate itself have been described as possible sources of infection, and the clothes or hands of the health staff as methods of transmission5.
We present two cases of AX that occurred in our department on the same date in patients undergoing the same HD session.
CASE 1
The patient was a 67-year-old female, from Bulgaria, hypertensive, diabetic, obese, with dyslipidaemia and chronic kidney disease (CKD) possibly secondary to diabetes and/or nephroangiosclerosis, on HD since January 2008. Low socioeconomic status, living with animals and bad personal hygiene.
Left humeral-cephalic arteriovenous fistula (AVF) was performed, with slow recovery, carrying out HD using a temporary CVC (multiple removals and new catheterisations due to infections of the catheter entry site).
The patient was admitted due to fever and shivers following dialysis, symptoms compatible with bacteraemia, with positive blood cultures of Staphylococcus (St.) aureus. There was associated infection in the catheter entry site, for which reason the catheter, which was cultured and resulted positive for AX, St. aureus and Enterococcus faecalis, was removed. The clinical and bacteriological infectious condition disappeared with combined treatment of the three bacteria.
CASE 2
A 46-year-old male patient, hypertensive, with hyperuricemia and CKD possibly secondary to chronic glomerulonephritis (GN), on HD since 1995. He received two cadaveric kidney transplants, with possible early recurrence of membranous GN and restarted HD in 2004.
The patient had multiple vascular accesses, the last being left humero-axillary prosthetic AVF (polytetrafluoroethylene), which resulted in ulceration on the skin close to the anastomosis with serous secretion, leaving the prosthesis exposed. A temporary CVC was implanted and a culture, growing AX, was taken from the ulcer. The patient did not show increase of acute phase reactants nor systemic infection data. He received intravenous antibiotics according to the antibiogram, after which the culture was repeated, with development of AX continuing. He received new courses of antibiotics, without managing to eradicate the bacterium (three AX positive cultures). Thus, surgical removal of the prothesis was decided upon and the implanting of a new vascular access (femoral saphenous AVF). The culture after the surgical wound tested negative for AX.
CONCLUSIONS
Although AX is not a common bacterium, it can be seen in HD patients.
In case 1, the patient had multiple factors for developing AX infection: contact with animals, poor socioeconomic conditions, poor personal hygiene and having a CVC. For these reasons, we think that it was the primary focus of the infection. The removal of the catheter and specific antibiotic treatment resolved the bacteraemia.
In case 2, colonisation of the prothesis could be due to transmission by the clothes or hands of the healthcare staff, since multi-dose vials were not used, nor were there other infections in the unit that could be associated with contamination of the dialysate. In this instance, as expected, the bacterium was not eradicated until removing the prosthetic material, despite receiving various courses of antibiotics according to the antibiogram. In addition, it is the first case described in the literature on fistula contamination by AX.
Conflicts of interest
The authors declare that they have no conflicts of interest related to the contents of this article.
