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Journal of Clinical Microbiology, April 2008, p. 1548-1550, Vol. 46, No. 4
0095-1137/08/$08.00+0 doi:10.1128/JCM.01040-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
| CASE REPORT |

Division of Infectious Diseases, Department of Internal Medicine,1 Department of Pathology and Research Center for Resistant Cells, Chosun University College of Medicine, Gwangju-si, South Korea2
Received 21 May 2007/ Returned for modification 5 September 2007/ Accepted 31 October 2007
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5.0 mg/ml), and a D-dimer concentration of 143.6 ng/ml (range, 0 to
255 ng/ml). On urinalysis, hematuria (score, +3) and proteinuria (score, +4) were shown to be present. A microscopic urinalysis revealed 10 to 19 red blood cells/high-power field (HPF), 2% dysmorphic red blood cells/HPF, 1 to 4 white blood cells/HPF, and no cast/HPF. A urinalysis using urine collected during 24 h detected selective proteinuria (albumin, 895 mg/day). Serologic tests were all negative for rheumatoid factor, antinuclear antibody, antineutrophil cytoplasmic antibody, and cold agglutinin, human immunodeficiency virus, hepatitis B virus, and hepatitis C virus antibodies, and the VDRL test was negative. Antistreptolysin O and complement levels were all normal. A self-employed person, our patient presented with no typical symptoms of scrub typhus, including rash, fever, and headache. He had a history of outdoor activity 10 days before admission. He had previously maintained a healthy life but had a markedly increased level of creatinine. He therefore received a renal biopsy for further evaluation and to make a differential diagnosis from other diseases, including rapidly progressing glomerulonephritis.
Tissue from the biopsy underwent immunohistochemical (IHC) staining and immunofluorescent staining, in which the primary antibody was ICR mouse hyperimmune serum immunized with Orientia tsutsugamushi strain Boryong at a dilution of 1:200. The antibody could detect other disparate strains of O. tsutsugamushi in addition to strain Boryong in the immunofluorescence assay (IFA) (data not shown). IHC staining was performed using a streptavidin-biotin immunoperoxidase method according to the supplier's protocol (LSAB kit; Dako, Carpinteria, CA), as described previously (2). Using renal biopsy, IHC staining, immunofluorescent staining, and electron microscopic examination (EM), we identified the presence of Orientia tsutsugamushi coccobacilli within the tubule. Based on these findings, a diagnosis of scrub typhus was established for our patient. He was immediately given doxycycline. An IFA serological test was performed using paired sera (2). At the time of admission, the patient's IFA serologic profile showed an immunoglobulin M (IgM) titer of 1:10 and an IgG titer of 1:4,096. One week after he was given doxycycline, samples from the recovery phase showed an IgM titer of 1:1,280 and an IgG titer of 1:4,096. A follow-up antibody test was performed to examine for the presence of concurrent diseases. The tests were all negative for endemic typhus, hemorrhagic fever with renal syndrome, leptospirosis, and measles. He recovered without any notable complications following doxycycline treatment. He was discharged when his serum creatinine levels returned to normal.
Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi, a gram-negative intracellular bacterium. Patients with scrub typhus present with an eschar at the site of the mite bite, a maculopapular rash, fever, myalgia, headache, and anorexia (4). The prognosis varies between patients, ranging from asymptomatic infection to death. Because scrub typhus causes systemic vasculitis, it can cause meningitis, interstitial pneumonia, acute pulmonary edema, hepatitis, and acute renal failure in untreated cases (6, 7, 8, 9). Hematuria and proteinuria may occur because of renal invasion in 10 to 20% of patients with scrub typhus. Acute renal failure is not a common entity, but it is known to be one of the serious complications seen in patients with scrub typhus, spotted fever, or murine typhus (3, 5, 10). Fever, headache, and rash are potential indicators for rickettsial disease and are known to be useful clues for the diagnosis of scrub typhus (1). However, our patient visited us with the chief complaint of a prompt deterioration of renal function without the triad of symptoms of scrub typhus, including typical skin lesions, fever, and headache. To identify the cause of the prompt deterioration of renal function, a renal biopsy with IHC staining, immunofluorescent staining, and EM were performed. This established a diagnosis of scrub typhus. An early recovery was achieved following doxycycline treatment.
In our case, a renal biopsy showed that the capillary loop and cellularity were normal in the glomerulus. The renal tubules underwent multifocal tubular necroses, and foci of some mononuclear cells were identified in the infiltration of the tubulointerstitium. Tubular epithelial cells underwent degenerative changes and were detached from the basement membrane (Fig. 1). Epithelial casts were observed in some renal tubules. These histopathologic findings were suggestive of acute tubular necrosis with chronic tubulointerstitial nephritis.
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FIG. 1. Histopathologic findings for the kidneys from a patient with scrub typhus. (a) Histopathologic findings for the kidneys (hematoxylin and eosin stain; magnification, x100). Acute tubular necrosis with chronic interstitial nephritis is illustrated. Many atrophic tubules and lumens containing desquamated epithelial casts (asterisks) are found. (b) Immunofluorescent staining of a kidney (magnification, x100). Positive immunofluorescent staining is indicated in the tubular structures (arrows). Scattered positive signals are also identified in the vascular structures (asterisks). (c) Immunohistochemical staining of a kidney (magnification, x100). Positive IHC staining is indicated in the tubular structures, and scattered positive signals are also identified in the vascular structures. (d) Ultramicroscopic findings of the renal tubular epithelial cells. Many O. tsutsugamushi (O) cells are seen in the cytoplasm. Many small vesicles (arrows) with an O. tsutsugamushi envelope appear around the degenerated Orientia coccobacilli (DO). Scale bar, 2.0 µm.
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In conclusion, our case highlights the following two points. First, in order to identify the cause of the prompt deterioration of renal function, a renal biopsy with IHC staining and EM was performed. The adequate use of IHC staining or EM established an early diagnosis of scrub typhus prior to serologic follow-up. Second, for our case, we demonstrated by IHC staining and EM for the first time that renal failure in patients with scrub typhus is caused by acute tubular necrosis due to the direct invasion of O. tsutsugamushi.
We declare no commercial interest and do not belong to any association that might pose a conflict of interest for this work.
Published ahead of print on 14 November 2007. ![]()
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