Peritonitis, pd-associated

Already in 1922 Putnam described the peritoneum as a dialysis membrane. The first peritoneal dialysis (PD) in humans was performed by Heusser and Werder in 1927.

But it was only the Silastic catheter developed by Tenckhoff in 1968 that made it possible for the catheter to remain in the abdominal cavity for a longer period of time. This eliminated the need for a new puncture, which had been necessary for every dialysis until then - and the associated increased risk of peritonitis decreased (Bauer 2009).

Intermittent peritoneal dialysis was initially used in hospitals and was largely replaced at the end of the 1970s by continuous outpatient peritoneal dialysis at home (Geberth 2011). Since the beginning of PD, the number of peritonitides caused by PD has been steadily decreasing (Kuhlmann 2015).

PD-associated peritonitis is a serious complication in the form of peritonitis in patients treated with PD (Geberth 2011).

The contamination can be intraluminal, periluminal, transmural or gastrointestinal (Geberth 2011).

The entry point of the catheter is classified in:

• four non-inflammatory conditions:
  • perfect
  • well
  • acceptable
  • traumatized
• three inflammatory states:
  • acutely inflamed
  • chronically inflamed
  • inflammatory changes in the area of the external cuff without signs of inflammation at the catheter exit site (Keller 2010)

In PD-associated peritonitis, mainly Gram-positive or Gram-negative bacteria are found, in rare cases enterobacteria or fungi.

Pathogens in decreasing frequency such as:

• coagulase-negative staphylococci
• staphylococcus aureus
• Streptococci
• E. coli
• Pseudomonas
• Enterococci
• Klebsiella
• Candida (Kuhlmann 2015)

Depending on the path of infection, different germs are found:

• intraluminal: almost exclusively skin germs such as:
  • Staphylococcus epidermidis
  • staphylococcus aureus
  • Acinetobacter
• periluminal:
  • staphylococcus epidermidis
  • staphylococcus aureus
  • Pseudomonas
  • Proteus
  • Yeast (for exit side tunnel infection)
• transmural: germs of the intestinal flora such as:
  • Anaerobes
  • Mushrooms
  • clusters of organisms
• ascending:
  • Pseudomonas
  • Yeast (Geberth 2011)

PD-associated peritonitis is the most frequent complication of PD (German Medical Association 2015) and is also the most frequent reason for a change of procedure.

In the early years of peritoneal dialysis, peritonitis occurred very frequently. However, due to improvements in connectors and technical developments, such as the introduction of the Y-system, it has become significantly less frequent.

The incidence of peritonitis was:

• 2011 in Australia at 0.43 episodes per year
• between 2000 - 2007 in Scotland at 0.63 episodes per year (Kuhlmann 2015)

For Germany, < 1 peritonitis in 60 months of treatment in adequately trained patients in experienced centres has been described (Schwenger 2007).

The most important sign of peritonitis is the clouding of the dialysate outlet, which is visible to the naked eye in pronounced findings. Patients are encouraged to place the outlet bag over a described document after each dialysis. If the writing is only vaguely visible, this indicates that the dialysate is cloudy (Kaufmann 2015).

As a rule, clouding of the drainage bag is the first symptom of peritonitis. In rare cases, however, the clinical symptoms may also be the primary symptom (Kaufmann 2015).

Symptoms of peritonitis can be:

• abdominal pain (80 %)
• fever (50 %)
• Nausea (30 %)
• Vomiting (30 %)
• Diarrhoea (7 % - 10 %)
• Defensive tension (10 % - 50 %)
• abdominal pressure pain (80 %)
• Pain of relinquishment
• Singultus (7 % - 10 %) (Kasper 2015 / Keller 2010 / Geberth 2011)

Any turbidity of the dialysate outlet bag should be clarified. Confirmation of the diagnosis is only possible by laboratory chemistry (Kuhlmann 2015).

Aerobic and anaerobic cultures from the dialysate and the blood should be applied, as well as a Gram stain in order to quickly detect fungal infections, most of which are severe, and a differential blood count is also required (Bauer 2009).

The peritoneal fluid contains:

• Leukocytes > 100 / µl, of which ≥ 50 % are polymorphonuclear neutrophils (PMN).

Kasper (2015) speaks of > 200 / µl.

The thresholds are usually lower than those for spontaneous bacterial peritonitis, since the glucose content of the dialysate and the absence of antibiotics contribute to a rapid multiplication of bacteria in the abdominal cavity (Kasper 2015).

Dialysate cultures are typically positive (Herold 2020).

If the patient is treated with automated peritoneal dialysis (APD), the diagnosis of peritonitis may be delayed, since the higher dialysate volumes and turnover in APD leads to a dilution of the leukocytes and thus the cloudiness of the dialysate is less detectable (Geberth 2011).

In most cases in-patient treatment is not necessary (Kasper 2015). However, the therapy of peritonitis should be carried out immediately. Initially with a broad-spectrum antibiotic, which detects Gram-positive and Gram-negative germs and is adjusted after receiving the dialysate cultures or the antibiogram (Geberth 2011).

Therapy recommendation e.g.:

• with a residual diuresis of < 100 ml / d:
  • Cefazolin 1.5 mg / kg KG Bag 1 x / d
  • plus
  • Gentamicin 0,6 mg / kg KG Bag 1 x / d
• with a residual diuresis of > 100 ml / d:
  • Cefazolin 20 mg / kg KG Bag 1 x / d
  • plus
  • Gentamicin 0,8 mg / kg KG Bag 1 x / d

Alternatively can be given:

• with a residual diuresis of < 100 ml / d:
  • Cefazolin 1,5 mg / kg KG bag 1 x / d
  • plus
  • Ceftazidim 1 g bag 1 x / d
• for a residual diuresis of > 100 ml / d:
  • Cefazolin 20 mg / kg KG Bag 1 x / d
  • plus
  • Ceftazidim 20 mg / kg KG bag 1 x / d (Geberth 2011)

The duration of therapy should be at least 2 weeks, in the case of S. aureus, enterococci and Gram-negative pathogens even at least 3 weeks.

Because of the risk of adhesions and catheter obstructions, intraperitoneal heparin should be administered (Herold 2020).

If the dialysate culture is still negative after 24 h - 48 h, the continuation of monotherapy with cefazolin (dosage see above) for 14 days is recommended if the symptoms improve clinically.

If, on the other hand, the dialysate cultures should be repeated after 96 h and Gram stains should be applied. In case of further symptoms and negative germ detection, the only remaining option is explantation of the catheter (Geberth 2015).

If the peritonitis is caused by hydrophilic Gram-negative germs, such as Pseudomonas or yeast fungi, an antimicrobial therapy is usually not sufficient. In these cases, explantation of the catheter is recommended for permanent restoration (Kasper 2015).

Although peritonitis caused by mycobacteria or fungi occurs only very rarely (< 2% [Bauer 2009]), in most cases it is preferable following antibiotic treatment (Kasper 2015).

The cure rate for peritonitis is approximately 80% for both continuous ambulatory peritoneal dialysis CAPD and APD (Geberth 2011).

Mortality: The mortality rate was 6 % in a Spanish study conducted in 2005, which included a total of 693 patients. Pathogens were in these cases:

• fungi 27.5 %
• intestinal germs 19,3
• Staphylococcus aureus 15.2 % (Fontan 2005)

For prophylaxis, daily cleaning and leaving serous crusts in place is recommended (Keller 2010). After a peritonitis has taken place, the patient must undergo a new standardized training to avoid further complications (Bundesärztekammer 2015).

After every successful peritonitis, the peritoneal transport properties should be checked with the combined modified peritoneal equilibration test (PET) approx. 4 weeks after discontinuation of the antibiotics (Geberth 2011).

(Kasper 2015)

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