Campylobacter spp. can cause either gastrointestinal or extra- intestinal infections . Although acute diarrheal illnesses are most common in Campylobacter jejuni, another Campylobacter spp., especially C. fetus may cause infections in virtually all parts of the body including septicemia, peritonitis, meningitis, endocarditis, septic arthritis, cellulitis and abortion more likely and gastroenteritis less likely [1-3]. C. fetus has been reported especially in patients with AIDS or other immunocompromised patients [1,3]. The cases of continuous ambulatory peritoneal dialysis (CAPD) infection caused by C. fetus have rarely been reported in global [3-7], especially the first case in Korea.
The objective of this study was to evaluate the accuracy of QMAC-dRAST AST system with faster protocol for staphylococci and enterococci cocci isolates originated from blood culture bottles. The accuracy was compared to that from MicroScan WalkAway plus system, commonly used as an automated AST system.
The patient was 73 year old with diabetes mellitus and chronic kidney disease (CKD) for 16 years and underwent CAPD for 2 years. He was admitted to the nephrology department with a 4-day history of abdominal pain, nausea and vomiting. CAPD peritonitis was suspected by the analysis of following tests at the time of admission. Laboratory tests showed a leukocyte count of 14,200/μL (segmented neutrophil 74.2%, lymphocytes 11.5%, monocytes 10.4%), and C-reactive protein (CRP) level of 9.1 mg/dL. And CAPD fluid contained 840/μL WBC with 85% polymorphonuclear cells. Cefazoline and ceftazidime treatment were started for empirical intraperitoneal antibiotics.
On the day of admission, Gram stain of the CAPD fluid was negative. But, CAPD fluid culture using blood bottles, C. fetus was identified. CAPD fluid cultures were inoculated using BacT/ALERT 3D (bioMérieux, Marcy-l’Etoile, France). On the third day of culture, bacterial growth was detected and Gram-negative curved rods were observed. The bacteria were cultivated in a Campy Blood-Free Selective Media agar medium (Asan, Seoul, Korea). The bacteria grew at 35°C at the duration of 2 days, but not grew in a micro-aerobic environment at 42°C. The results of the additional identification test on the colony are as follows: oxidase test was positive, hippurate hydrolysis test was negative, and cephalothin was susceptible. For further identification of bacterial species, polymerase chain reaction (PCR) for 16S rRNA gene sequencing was carried out. The universal primers 27F (5′-AGAGTTTGATCCTGGCTCAG-3′) and 1492R (5′-GGTTACCTTGTTACGACTT-3′) were used to amplify parts of the 16S rRNA gene. The strain was the most closely matched to that of C. fetus subsp. fetus ATCC27374 (GenBank accession number NR043597.1) with 99.9% identity (1314/1315 bp). Antimicrobial susceptibility testing was performed by E-test and interpreted according to the Clinical and Laboratory Standards Institute (CLSI) guidelines . The medium used was Mueller-Hinton agar with 5% sheep blood. The plates were incubated in a micro-aerobic environment for 24 hours at 35°C. The antimicrobial materials used were ciprofloxacin and erythromycin. C. fetus was both susceptible to ciprofloxacin (minimum inhibitory concentration=0.25 μg/mL) and erythromycin (0.38 μg/mL). Additional treatment using ciprofloxacin was started. After 2 weeks of intraperitoneal antibiotic treatment, the patient's symptoms was improved and discharged.
However, four months later, the patient was readmitted with abdominal pain and cloudy dialysate from 3 days before admission. CAPD peritonitis was recurrently diagnosed at the time of admission from the analysis of following tests. Laboratory tests showed leukocyte count of 11,600/μL (segmented neutrophil 64.0%, lymphocytes 17.4%, monocytes 9.6%) and CRP level of 9.0 mg/dL. CAPD fluid contained 40/μL WBC with 80% polymorphonuclear cells. The patient underwent intraperitoneal antibiotics treatment with cefamezin and ceftazidime in the CAPD transfer set. However, at that time, Gram stain and culture of the CAPD fluid were negative. After 10 days of intraperitoneal antibiotic treatment, patient symptoms and test results improved, outpatient follow-up and peritoneal dialysis has been maintained after discharge.
There have been so many different species causing CAPD infection. Most series have found coagulase-negative staphylococci to be the most frequently encountered agents (40% to 60%), followed by S. aureus and streptococcus spp. (10% to 20% each), Enterobacteriaceae (5% to 20%), nonfermentative gram-negative rods (3% to 15%), and gram-positive rods (2% to 4%). Values for mixed bacteria, fungi, mycobacteria, and anaerobes are generally <5% .
Campylobacter spp. can be detected by Gram stain examination from a colony on a primary isolation plate. They have characteristic microscopic morphology: small, curved or seagull- winged gram-negative rods . If the colony is suspicious- looking at Campylobacter spp., it must be cultured to selective agars and incubated at 35°C in a micro-aerobic atmosphere. To identify species of Campylobacter spp., the incubation of three inoculated plates at 42°C, 35°C and 25°C should be required because they have different optimum temperatures . C. coli and C. jejuni could grow at 42°C, but C. fetus could not. In this case, C. fetus isolate showed poorly growth at 42°C but well growth at 35°C. Also, susceptibility to nalidixic acid and cephalothin is an important differential characteristic among species. Molecular assays using PCR-based amplification of the 16S rRNA gene and direct sequencing of the PCR product have successfully identified the majority of Campylobacter species. C. fetus is generally susceptible to many antibiotics: erythromycin is the regimen of choice, with ciprofloxacin as an alternative drug [1,11]. The rate of resistance to erythromycin was about under 10% in Korea. However, the resistance rates to ciprofloxacin were different from 20% to 100% in Korea [10,12,13]. In this case, C. fetus was susceptible to ciprofloxacin.
In this case, the portal of entry of C. fetus is unclear, but might be due to infectious colitis. The patient was diagnosed with infectious colitis in the colonoscopy. Also, abdominal CT showed edematous wall thickening of sigmoid colon and peritoneal dialysate in perihepatic space and pelvic cavity. These findings suggest that intestinal bacteria may have spread into the peritoneal cavity. Inappropriate use of peritoneal catheter or exit- site infection can also increase the risk of CAPD peritonitis [5,14].
Nearly all patients without compromised or systemic infection recover from C. fetus gastroenteritis, especially without antibiotic therapy. However, immunocompromised persons or those with bacteremia or other extra-intestinal infection may require a prolonged course of antimicrobial treatment. Endovascular infections and immunocompromised patients with systemic infections due to C. fetus should be treated for at least four weeks. Persistent or relapsing infection with C. fetus can occur even years after the initial diagnosis [2,11]. In this case, although C. fetus was not recovered from CAPD fluid on 2nd peritonitis event, the recurrent infection due to C. fetus might be suspicious. It is significant that this is the first case report of CAPD peritonitis caused by C. fetus in Korea.