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Incidence of peritonitis

From 114 institutions (26 university hospitals, 67 hospitals with more than 100 beds,
4 clinics with beds for admission, 17 clinics without beds for admission), information
regarding 3042 PD patients, including 516 peritonitis patients, was obtained, covering
a total observation period of 31,686 patient months. The incidence of peritonitis
was calculated to be 0.195 episodes per year.

Peritonitis patient characteristics

We obtained the clinical characteristics of the 466 peritonitis patients who had a
total of 544 peritonitis episodes; 59 patients had multiple peritonitis episodes (an
episode that occurred within 2 weeks of completion of therapy for a prior episode
was defined as 1 peritonitis episode). Characteristics of these 466 patients are shown
in Table 1. The average frequency of past peritonitis episodes was 0.85?±?1.20. There are two
methods used in Japan for connecting a PD fluid bag to the catheter. One is by manual
connection, and the other involves use of machinery for ultraviolet irradiation or
heat sealing of the catheter to the PD fluid bag. The numbers of episodes using each
were manual method, 206 and machinery device method, 303. There was no statistical
difference between manual connection and machinery device connection methods for the
frequency of past peritonitis episodes.

Table 1. Characteristics of 466 PD peritonitis patients

Characteristics of 544 peritonitis episodes are shown in Table 2. The average PD treatment duration at the time of a peritonitis episode was 36.1?±?32.7 months;
407 patients had 1 episode of peritonitis, and 59 patients had several peritonitis
episodes during the study period.

Table 2. Characteristics of 544 peritonitis episodes of 466 PD patients

Causes of peritonitis

The causes cited for peritonitis episodes included the following: contamination during
the peritoneal fluid bag exchange (touch contamination), 130 episodes (23.9 %); influence
of intra-abdominal cavity infection, 58 episodes (10.7 %); exit-site infection, 55
episodes (10.1 %); and unknown, 207 episodes (38.1 %) (Fig. 1).

Fig. 1. Causes of peritonitis

Bacterial cultures of peritoneal effluent

Figure 2 depicts the various methods of effluent culture reported in this survey, including
the use of a blood culture bottle, 50.9 %; large-volume culture (culturing the effluent
sediment after centrifugation, in a culture dish or blood culture bottle), 31.7 %;
and direct culture of effluent in a culture dish, 12.7 %.

Fig. 2. Effluent culture methods (including overlapping answers)

Microbiology of effluent cultures

Among effluent cultures, 131 episodes were culture-negative, 270 episodes yielded
Gram-positives, 116 yielded Gram-negatives, and 42 yielded “other” microbes (Table 3). In addition, 32 episodes were poly-microbial. The rank order of infecting organisms
was culture-negative bacteria, Streptococcus sp. and Staphylococcus aureus.

Table 3. Microbiology of peritoneal effluent cultures (including overlap)

Antibiotic treatments

Initially, empiric antibiotic treatments were reported for 540 episodes (Fig. 3). Cefazolin (CEZ) was the most frequently selected agent, followed by ceftazidime
(CAZ), vancomycin (VCM), cefotiam (CTM), and cefmetazole (CMZ). In total, 406 episodes
(75.2 %) were treated with antibiotic combinations: the second antibiotic agents used
in combination therapy included CAZ, tobramycin (TOB), VCM, CEZ, and amikacin (AMK).
Only one case was treated empirically with three antibiotics. The most common combination
therapy was CEZ + CAZ (112 cases).

Fig. 3. Antibiotic therapy: administration methods and durations. a First empiric antibiotic (540 cases). b Second empiric antibiotic (406 cases). c Third antibiotic, targeted for known susceptibility (278 cases). d Fourth antibiotic, targeted for known susceptibility (79 cases). In total, 406 cases
(75.2 %) were treated with combined empiric therapy; 278 cases were switched to targeted
antibiotics after empiric antibiotic administration. Intraperitoneal administration:
277 (51.4 %) for first antibiotic and 236 (59.4 %) for second antibiotic. Total administration
periods were 16.5?±?9.3 days. CEZ cefazolin, CAZ ceftazidime, VCM vancomycin, CTM cefotiam, CMZ cefmetazole, TOB tobramycin, AMK amikacin, MEMP meropenem, LVFX levofloxacin, CCL cefaclor, RFP rifampicin, IP intraperitoneal cavity administration, IV intravenous administration

Administration methods for first antibiotic agents included intraperitoneal (IP),
277 (51.4 %) cases and intravascular (IV), 250 (46.4 %) cases. Administration methods
for second antibiotic agents were IP, 236 (59.4 %) cases and IV, 145 (36.5 %) cases.
Mean treatment periods were 8.9?±?5.6 days for first antibiotics and 8.0?±?5.2 days
for second antibiotics. The mean treatment period for cases receiving only empiric
therapy was 10.8?±?5.4 days.

After the first, empiric antibiotic administration, 278 cases were switched to targeted
antibiotics; 79 of these were treated with two antibiotics and 5 were treated with
three antibiotics. The mean total length of therapy with targeted antibiotics was
16.5?±?9.3 days.

Effect of treatment

Of the 544 peritonitis episodes, 461 (84.7 %) were able to continue PD treatments
after the peritonitis resolved: 19 (3.5 %) underwent removal and reinsertion of the
catheter. However, 80 (14.7 %) withdrew from PD treatment and transferred to periodic
hemodialysis treatment, and 6 (1.1 %) died. The prognosis of three patients was not
obtained from the questionnaires.

The main microorganisms of cases withdrawn from treatment were as follows: methicillin-resistant
S. aureus (MRSA), 12; S. aureus, 6; Escherichia coli, 6; other Gram-negative, 6; other bacteria, 6; Streptococcus sp., 5; Pseudomonas sp., 5; and culture-negative, 15. The total treatment period for peritonitis in these
cases was 20.5?±?13.7 (1~80) days.

Bacteria causative of the six deaths were as follows: MRSA, two; Escherichia coli (E. coli), one; Pseudomonas sp., one; other bacteria, one; and culture-negative, one. The course of one patient
who died was complicated by hepatic carcinoma and relapsing peritonitis, and the infection
routes in the other five patients were touch contamination, three; extension of intra-abdominal
cavity infection, one; and unknown reason, one. Antibiotic administration methods
were IP, one; IV, four; and oral, one. The mean treatment period for these six patients
was 10.3?±?5.5 days (range 1–17 days).

Antibiotic administration method and prognosis

We analyzed the influence of empiric antibiotic administration method on prognosis
using Pearson’s chi-square test (Fig. 4). In the oral administration group, the rates of mortality and catheter replacement
were higher than those in the IV or IP groups. The rates of PD continuation, catheter
replacement, withdrawal from PD, and mortality among groups of patients undergoing
the three different antibiotic administration methods (oral, IV, and IP) were statistically
different (P??0.0001).

Fig. 4. Influence on prognosis of empiric antibiotic administration method. The rates of PD
continuation, catheter replacement, interruption of PD, and mortality for the three
different administration methods were statistically different (P??0.0001). PD peritoneal dialysis, IP intraperitoneal cavity administration, IV intravenous administration

Clinical findings and PD treatment withdrawal

We examined the association of clinical findings and PD treatment withdrawal using
logistic regression analysis. The dependent variable was withdrawal from PD (including
death); the independent variables were age, PD treatment period, original disease,
exit-site infection, touch contamination, intra-abdominal cavity infection, infection
from defective device and methodology, infection at catheter placement, and frequency
of past peritonitis. We selected the statistically significant variables from these
independent variables using the stepwise method; PD treatment period, exit-site infection,
intra-abdominal cavity infection, and frequency of past peritonitis were then analyzed
using logistic regression analysis. A significant association was observed between
withdrawal from PD treatment and exit-site infection (OR 2.56, P?=?0.007) as well as between withdrawal from PD and frequency of past peritonitis
(OR 3.041, P??0.0001) (Table 4). Based on these results, exit-site infection and frequency of past peritonitis were
considered important factors that affect the prognosis of PD peritonitis patients.

Table 4. Association between interruption of PD and clinical findings