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Journal of Clinical Microbiology, September 2004, p. 4405-4407, Vol. 42, No. 9
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.9.4405-4407.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
| CASE REPORT |
Departments of Medicine,1 Microbiology,2 Pathology New York University School of Medicine,3 Department of Veterans Affairs Medical Center New York, New York4
Received 6 February 2004/ Returned for modification 6 May 2004/ Accepted 27 May 2004
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ABSTRACT |
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CASE REPORT |
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On the day the patient was admitted to the hospital, he reported worsening cough, fever, and epigastric pain. On examination, he appeared to be moderately ill with a temperature of 39.4°C, pulse of 110 beats/min, blood pressure of 110/48 mm of Hg, and respiratory rate of 14 breaths/min; his physical examination was otherwise normal. The leukocyte count was 3,900/mm3, with an absolute neutrophil count of 2,650/mm3 and a platelet count of 52,000/mm3. He had 6.6 g of hemoglobin per dl. The chest X-ray was normal. After cultures were obtained, he was given cefepime intravenously. Two days after admission, one of four blood culture bottles was reported as growing Campylobacter species. Cefepime was changed to imipenem-cilastatin. He also was noted to have erythema and tenderness of the right arm in an area near a prior phlebotomy site. Vancomycin was added for presumed cellulitis and was continued for 1 week, with complete resolution of erythema. Multiple stool cultures (obtained after antibiotics were begun) were negative for Campylobacter species. Twelve days after admission to the hospital, the bloodstream Campylobacter isolate was noted to be resistant to trimethoprim-sulfamethoxazole but susceptible to levofloxacin, and the patient was discharged on oral levofloxacin (500 mg per day for 2 weeks).
The patient recovered and was readmitted 3 weeks later for elective chemotherapy with cytarabine and etoposide. Four days after admission to the hospital, he developed abdominal pain and a temperature of 38.9°C. The chest X-ray was normal. After blood cultures were obtained, the patient was empirically treated with cefepime and metronidazole, which was changed 4 days later to intravenous levofloxacin and metronidazole. The absolute neutrophil count at that time was 11,300/mm3, which subsequently decreased to a nadir of <50/mm3 7 days after admission to the hospital. Abdominal tomography revealed pancolitis. Stool culture and stool Clostridium difficile toxin assays were negative. Eight days after admission to the hospital, the patient had improved and was discharged on a 10-day regimen of levofloxacin and metronidazole. Subsequently, the blood cultures obtained on admission again grew a Campylobacter species in one of four bottles, susceptible again to levofloxacin and tetracycline. On the basis of the recurrent Campylobacter isolations, levofloxacin then was continued prophylactically for the duration of subsequent chemotherapies.
Campylobacter fetus is a gram-negative, slender, spiral, bacterial pathogen that may cause enteritis, abortion, bacteremia, endocarditis, or meningitis in humans (4, 15). C. fetus may be either type A or type B based on serotype, lipopolysaccharide structure, and surface layer protein (SLP) type (5, 9, 12). The C. fetus species is currently divided into C. fetus subsp. fetus and C. fetus subsp. venerealis. C. fetus has been isolated from ungulates, swine, humans, birds, and reptiles (7, 14). In 1985, Harvey and Greenwood reported the isolation of C. fetus from turtles owned by an ill child (7). Methods to distinguish C. fetus strains of mammal and reptile origin have been published recently (16). We now report the first confirmed isolation from a human of C. fetus with markers of reptile origin. In this case, the patient was symptomatic due to recurrent bacteremia with this organism.
Microbiology. Growth of both isolates on blood agar plates occurred at 37 and 42°C using a CampyPak envelope (Becton Dickinson, Sparks, Md.) to create microaerobic conditions. The organisms were gram negative, curved, catalase positive, oxidase positive, H2S producing, resistant to nalidixic acid and cephalothin, and unable to hydrolyze hippurate. Antibiotic susceptibility was determined using E Test (AB Biodisk North America, Piscataway, N.J.) as described previously (8). The characteristics of these strains, designated 03-427 and 03-445, were consistent with those of Campylobacter species.
To determine whether the isolates were C. fetus, PCR was performed with primers SDF01 and SDR01, specific for C. fetus sapD (16, 17). From both strains isolated, the expected 542-bp sapD band was amplified, identical to that for C. fetus strain 23D (Fig. 1A). To further characterize the C. fetus strain type, PCR was performed using primers specific for sapA (SAF01 and SAR01) or for sapB (SBF01 and SBR01) (16). In total, the results of these molecular studies indicated that both strains isolated were type A C. fetus (Fig. 1B and C). Since SLPs have been shown to be the major C. fetus virulence factors (3, 6), strains 03-427 and 03-445 were analyzed for SLP expression using a polyclonal antibody raised against the 97-kDa major SLP of type A strain 82-40LP (10) as described previously (18). The immunoblot analysis showed that each strain expressed a 97-kDa protein as its major SLP (Fig. 2).
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Further molecular characterization of strains. On the basis of our previous study, reptile C. fetus strains may possess a 187-bp noncoding DNA insertion near the upstream boundary of the sap island. To test this property in the two strains isolated, we performed PCR using the 187-bp insertion-specific primers IF and IR (18). The results indicated that the strains isolated each possess a positive band (Fig. 1D). Sequence analysis of the PCR product amplified from strain 03-427 showed a 9-bp (ATTTATTTA) deletion at bp 53 of the amplified 149-bp product in strain 85-388 (18) and seven other single-nucleotide polymorphisms compared with the sequence of strain 85-388 (data not shown).
Randomly amplified polymorphic DNA (RAPD) can been used to distinguish the mammalian and reptilian C. fetus strains (Z. Tu and M. J. Blaser, unpublished data). Analysis with RAPD and primer 1254 (1) showed that the two isolated C. fetus strains produce 1.2-, 1.6-, and 2.5-kb bands, consistent with analysis of reptile C. fetus strain 85-388, whereas the two mammalian strains 23D (type A) and 84-107 (type B) produce 2.5- and 3.0-kb bands, as expected (Fig. 1E).
C. fetus isolates from reptiles differ from C. fetus subsp. fetus and C. fetus subsp. venerealis based on the results from 16S rRNA, recA, and sapD sequence analyses and may be a new Campylobacter species or subspecies (16). A C. fetus strain isolated from a turtle was suggested to be the cause of an acute diarrheal illness in a human, but there was no isolate from the affected child (7).
Genotypic approaches utilizing PCRs specific for sapA, sapB, reptile sap island insertion, and RAPD, as well as sapD and 16S rRNA molecular sequencing methods, allowed us to identify a C. fetus type A strain of reptile origin in this patient with recurrent bacteremia. To our knowledge, this is the first confirmed human infection with a C. fetus strain with markers of reptile origin. How the patient acquired the organism is unknown. Neither the patient nor his relatives and friends kept any pet reptiles, and he denied consuming unpasteurized dairy products, which have been linked to C. fetus infection (13). Although he did not consume any reptile products near the time of his illness, he had eaten turtle soup during the prior year, and his family occasionally prepared turtle soup. Whether the characteristics we described are specific for reptile isolates or reflect a broader, as yet undefined, environmental niche is unknown. However, the deep branching observed between the mammalian and reptile isolates (16) is consistent with an ancient dichotomy. Other large-scale studies of C. fetus (19) have not indicated other dichotomies as substantial as those between mammal and reptile isolates.
The occurrence of bacteremia in a debilitated host is consistent with the role of C. fetus as an opportunistic pathogen. It is possible that prophylaxis with trimethoprim-sulfamethoxazole may have predisposed to C. fetus infection, since these antimicrobial agents may have suppressed the normal flora, but most Campylobacter strains are resistant to trimethoprim (2). How often C. fetus strains of reptile or related origin actually cause human disease remains to be determined. The fastidious nature of C. fetus and suboptimal detection in commonly used blood culture systems (20) suggest that its occurrence is underrecognized.
Nucleotide sequence accession numbers. The 16S rRNA and partial sapD sequences of the isolate have been deposited in the GenBank sequence database under accession numbers AY621303 and AY621304, respectively.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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