Reversible Thick Ascending Limb Dysfunction and Aseptic Meningitis Syndrome: Early Manifestation in Two Leptospirosis Patients

Abstract

Leptospirosis is a widespread spirochetal zoonosis caused by the members of the genus Leptospira. The natural history of human leptospiral infection varies widely. The infection can cause a subclinical illness, or may be mistaken for influenza. In individuals who become ill, leptospirosis typically presents as one of two clinically recognizable syndromes. The first syndrome is the mild anicteric form, which rarely results in death, while the second syndrome fulminant icteric form, known as Weil's syndrome, has an associated 10% mortality. The anicteric form comprises two disease stages, namely the septicemic phase and the immune phase. In fever work up, leptospirosis is usually not the first considered pathogen of sepsis, unless jaundice and ARF are present. This study investigated two patients with leptospirosis presenting with conscious disturbance and oligoric acute renal failure individually. In the second patient, persistent hypokalemia and metabolic alkalosis developed during recovery from acute renal failure. Several tubular function tests were performed to define the renal tubular lesion in this patient, revealing a defect on the thick ascending limb. This study also reviews previous studies on leptospirosis including its epidemiology, pathogenesis, clinical presentation, diagnosis, treatment, and prognosis.

• Leptospirosis
• Thick ascending limb dysfunction
• Acute renal failure
• Aseptic meningitis syndrome

Introduction

Leptospirosis is a widespread spirochetal zoonosis caused by members of the genus Leptospira. Leptospirosis has been isolated from reptiles, amphibians, fish, birds, and invertebrates. The infection occurs throughout the year in tropical and subtropical areas, and can also occur in temperate zones during the warm and rainy seasons. Transmission is usually via contact with urine from infected animals.[[1]] Clinically, leptospirosis is a biphasic illness. The initial septicemic phase lasts for 4–7 days and is generally mistaken for an influenza-like illness. In the secondary immune phase, leptospires are eliminated from the blood and CSF. However, the circulating antibody may cause immune-mediated meningitis, uveitis, rash and, rarely, fulminant hepatic jaundice, renal failure, and pulmonary hemorrhage (Weil's syndrome).[[2]] In fever work up, leptospirosis is usually not the considered pathogen of sepsis, unless jaundice with ARF is present. This study investigated two patients with leptospirosis, both of whom presented individually with conscious disturbance and oligoric acute renal failure. In the second patient, persistent hypokalemia and metabolic acidosis developed during the recovery phase of acute renal failure. Several clearance studies were performed to define the renal tubular lesion in this patient.

Case Report

Case 1

A 31-year-old man was sent to the Emergency Department of Chang Gung Memorial Hospital (CGMH) on January 6, 2001 with conscious disturbance. The patient was a habitual drinker and used to live alone. According to acquaintances, the patient had developed an upper respiratory infection with intermittent fever, headache, and mild cough several days before admission. Physical examination revealed a comatose (Glasgow coma scale E3V1M4), acute ill-looking male. Vital signs were temperature 36.9°C, pulse rate 117 beats/min, respiratory rate 24 breaths/min, and blood pressure 117/70 mmHg. Examination of the head and neck area found anicteric sclera, pupil size 4/4 mm, light reflex +/+, negative doll sign, supple neck, and no lymphadenopathy. The breathing sound was bilateral crackle. Moreover, heart sound was regular without any murmur. The abdomen was soft and flat with normal active bowel sound. The patient's legs exhibited no pitting edema. Additionally, the skin was intact. There was also no focal neurological deficit. Finally, the Kernig's and Brudzinski's signs were both negative.

The laboratory values were serum creatinine (Cr) 1.4 mg/dL, calcium 9.0 mg/mL, sodium 144 meq/L, potassium 4.7 meq/L, Ammonia 37 µg/dL, alcohol level <5 mg /dL, and urinary benzodiazepam level <40 ng/mL. The complete blood cell count was WBC 20700/uL with 81.5% segmented neutrophils, 8.5% lymphocytes, and 10% monocytes; hematocrit 45.7%, and platelet 261000 cells/µL. Arterial blood gas displayed pH 7.464, PCO2 29.0 mmHg, PO2 92.1 mmHg, and bicarbonate 20.8 mmol/L with room air. Besides, CK-MB was 259 U/L and CK was 11811 ng/mL. Brain CT was performed to exclude organic brain lesion but revealed symmetric low density at bilateral globus pallidus. The next day, the serum osmolarity was 278 mosm/KgH₂O, myoglobulin was 633 µg/L and urinary myoglobulin was 5870 µg/L. Moreover, urinary amphetamine level below 500 ng/mL. On the third day, serum aspartate aminotransferase (AST) was 353 U/L and alanine aminotransferase (ALT) was 141 U/L.

Because no infection focus was found during fever work up initially, an abdominal ultrasound was done on January 10 to survey intraabdominal abscess and found only mild splenomegaly (spleen index 5.0 × 4.4 cm). Lumbar puncture was done for cerebrospinal fluid (CSF) study on January 11 owing to persistent drowsy consciousness. The CSF data appeared clear and colorless, and displayed positive protein by the Pandy test; WBC 6 cell/µL (1 neutrophil and 5 lymphocytes); RBC 1 cells/µL, and no visible bacteria or fungus in Gram stain, acid-fast stain, or Indian ink stain. Finally, the CSF revealed protein 32.6 mg/dL, lactate 10.5 mg/dL, and no cryptococcal antigen.

The patient was empirically treated with Penicillin (3000000 u q6 h) and Ceftizoxime (2 g q8 h) for suspected aseptic meningitis. Consciousness improved gradually from January 13. Serum and urine specimens gathered on January 11 were reported to be positive for leptospiral antibody (serovar shermani) by a MAT with titer of 400x conducted by the Department of Veterinary Medicine of National Taiwan University (NTU) on January 17. The patient was discharged on January 22. The following MAT on January 18 was negative.

Case 2

The patient, 47-year-old, male, was generally well and denied suffering any systemic disease. The patient had gradual onset of general malaise, poor appetite, abdominal pain, and right flank pain from one week before admission. The patient was sent to a local medical department for first aid and abnormal liver function was found. He was transferred to the Emergency Department of CGMH on May 13, 2001. Physical examination revealed body temperature 37°C, blood pressure 108/66 mmHg, respiratory rate 21 breaths/min, and pulse 86 beats/min. The patient was acute ill looking, with icteric sclera, pupil size 4/4 mm, light reflex +/+. The neck was supple without lymphadenopathy. Breathing displayed bilateral mild crackle, and heart sound was regular without murmur. The abdomen was soft and flat, and had a normal active bowel sound without tenderness. Finally, the legs were freely movable with mildly pitting edema.

Laboratory examination found serum AST 819 U/L, ALT 710 U/L, Alkaline phosphatase 66 U/L, direct bilirubin 1.9 mg/dL, total bilirubin 2.6 mg/dL, blood urea nitrogen (BUN) 64 mg/dL, (Cr) 6.5 mg/dL, sodium 140 meq/L, potassium 4.3 meq/L, amylase 1287 U/L, lipase 80 U/L, prothrombin time 13.6 s (normal control 12.3 s, INR 1.11), activated partial thrombin time 35.7 s (normal control 29.6 s), hematocrit 31.6%, WBC 19000/uL with 81% segmental neutrophil, 6% monocyte, 5% lymphocyte, and platelet 22000/uL. Additionally, arterial blood gas was pH 7.364, PCO2 34.9 mmHg, PO2 120.8 mmHg, and bicarbonate 19.5 mmol/L with FiO2 40%. Empiric antibiotic treatment began with Penicillin (3000000u g8 h) and Ceftizoxime (1 g q8 h) to cover Gram-positive cocci and Gram-negative bacilli. On May 15, the following data were checked under suspecting acute viral hepatitis: albumin 3.3 g/dL, total protein 5.7 g/dL, rGT 22 U/L, glucose 82 mg /dL, negative anti-HBe (1.67/1.0/ABBOTT), negative anti-HAV IgM (0.26/1.2/ABBOTT), and negative HCV-Ab (0.23/1.0/ABBOTT-III). On May 16, BUN was 99 mg/dL, Cr 12.1 mg/dL, amylase 172 U/L, lipase 490 U/L, direct bilirubin 0.5 mg/dL, total bilirubin 1.1 mg/dL, AST 39 U/L, calcium 6.9 mg/dL, phosphate 1.3 mg/dL, sodium 127 meq/L, potassium 3.4 meq/L, chloride 98 meq/L, glucose 131 mg/dL, and platelet 27000/uL. Oliguria persisted since May 13. For fluid overloading and hypercatabolism, intermittent hemodialysis was initiated from May 16. The urine routine showed yellow and turbid appearance, with specific gravity 1.01, pH 8.0, leukocyte esterase 2+, nitrite negative, protein 500 mg/dL, glucose 0.05 mg/dL, negative ketone, urobilinogen 0.1 EU/dL, blood 4+, RBC>100/HPF, and WBC 1-2/HPF. Creatinine clearance rate (CCR) was only 0.36 cc/min on May 18. Because of abdominal pain and high amylase and lipase, abdominal computer tomography was performed to exclude pancreatitis or hollow organ perforation. However, no evidence of acute pancreatitis or hollow organ perforation was found. On May 21, the ascites routine was conducted to exclude peritonitis and the data revealed red and turbid in appearance, specific gravity 1.03, positive protein detected by Rivata test, WBC 189 cells/uL with 92% neutrophil and 8% lymphocyte, RBC 6831 cells/uL, negative Gram stain. Because of combination of liver injury and renal failure, leptospirosis was taken into account. The serum collected on May 16 displayed positive leptospiral antibody (serovar shermani) by MAT with a titer of 400 times from the Department of Veterinary Medicine of NTU on May 23. After antibiotics treatment, total urine amount exceeded 400cc/day since May 20. Due to prolonged high values of BUN and Cr, renal biopsy was done for pathological study on May 28. In light microscopy, the glomeruli showed mild to moderate ischemic collapse and mild mesangial hyperplasia and sclerosis. There were RBCs and protein casts in the tubules and mild tubular degeneration was noted. Moreover, the interstium had focal patchy moderate chronic inflammation and mild fibrosis. Electric microscopy showed focal sclerosis of the basal membrane with degeneration and focally persevered the foot processes. Hemodialysis was discontinued on May 26, after administering a total of 5 doses. Serum creatinine level declined to below 10 mg/dL after May 30 and renal function improved day by day.

Several tubular clearance tests were performed to evaluate the specific tubular function deficit.[[3]] Specifically, bicarbonate-loading test was done to detect proximal acidification and distal proton pump function. The fraction excretion of bicarbonate (FeHCO3⁻) increased from less than 3% to 4.7%, and the urine-blood PCO2 gradient (Δ U-BPCO2) was 28 mmHg after bicarbonate infusion. There was no glucosuria, and uric acid excretion (406 mg/day) and phosphate excretion (567 mg/day) were within normal limits. The above findings suggest that the proximal bicarbonate reabsorption and the proton pump in the intercalated cells of the cortical collecting tubules were intact. Moreover, a furosemide test was performed to evaluate sodium chloride reabsorption on the thick ascending limb of Henle. The fraction excretion of potassium (Fek), osmolar clearance (Cosm), chloride clearance (C_Cl), and urine pH remained unchanged after furosemide administration (FeK 17.89% → 20.65%, Cosm 4.82 → 4.92 mL/min/100mLGFR, C_Cl 3.47→3.92 → mL/min/100 mLGFR, urinary pH 7.36 → 7.40). The results indicated an impaired sodium–potassium–chloride cotransporter over the thick ascending limb. Additionally, a thiazide test was to evaluate Na⁺–Cl⁻ cotransport of the distal tubule. The fraction excretion of chloride increased from 3% to 12% after thiazide administration. These results indicated an intact sodium chloride reabsorption mechanism in the distal tubule.

Both antibiotics were discontinued and replaced with oral Doxycycline (100 mg bid) on June 2. Another serum specimen for leptospira antibody detection on June 5 was negative. The patient asked to be discharged against advice on June 14 with Cr level 2.4 mg/dL and BUN 49 mg/dL.

Discussion

Leptospires are obligate aerobes that present as motile, flexible, tightly corked, helicoidally rods with a unique terminal hook, and are 0.1–0.2 µm in diameter and 6–20µm in length. Leptospires cannot be seen in Gram stain smear and are only faintly colored by Giemsa or Wright's stain. However, leptospires can be seen on dark-field microscopy. Leptospires can be cultivated using Fletcher's medium, the new EMJH, and Tween 80 albumin media. Leptospires can survive in warm, wet environments with neutral to slightly alkaline water. Leptospires are the only pathogenic spirochetes able to live freely, outside of animals, in the environment. In contrast, Treponema pallidum resides only in humans, while Borrelia spirochetes reside only in anthropoids or mammalian hosts. Leptospires infect human hosts by entering them though cuts or abrasions to the skin, mucosa, or conjunctivae.

Weil first described leptospirosis in 1886 when he differentiated its severe icteric form from other icteric illness. In 1915, Inada et al. identified the cause of this disease by cultivating the spirochete “Spirochaeta icterohaemorrhagiae”. Leptospirosis was first reported in Taiwan in 1976.[[4]] However, leptospirosis was ignored as a cause of acute renal failure in Taiwan until Yang et al. reported two cases of jaundice and renal failure in 1997.[[5]] Leptospirosis was not initially considered in those cases, and thus the potential risk factors were not recognized. Before 1970, most reported cases of leptospirosis involved occupational exposure, but after the 1970s, most cases involved transmission in home and recreational settings.[[6]] Significantly, rodents are an important reservoir of leptospirosis worldwide. Vinetz et al.[[2]] implicated rats as the vector in urban leptospirosis in Baltimore. Moreover, reports exist of leptospirosis being acquired in New York City without recent travel history.[[7]] The two cases described here had little probability of contacting the pathogen in their workplace. Thus, we think that they were exposed to Leptospires either at home or during their recreational activities. In Taiwan, most leptospiral infections are caused by Leptospira shermani,[[8]] which was also the pathogen in the two cases described here. The Jarish–Herxheimer reaction, which is characterized by a sharp temperature rise and marked drop in blood pressure may occur following treatment with Penicillin, and was first reported as early as 1951.[[9]] However, the two cases described here did not display the Jarish–Herxheimer reaction. Even the previous report,[[8]] described only one case of Jarish–Herxheimer reaction occurring in Taiwan.

The standard for making a diagnosis of leptospirosis is culture identification from any clinical specimen. However, the incubation period ranges from a few days to four weeks. Besides, such culture identification is difficult to achieve in practice because most clinical laboratories do not have the specialized media required. The MAT is the standard serologic test used by reference laboratories such as the Center for Disease Control (CDC). This test is thus the test of choice, but is only available at CDC in the US and at the Department of Veterinary Medicine of NTU in Taiwan. Furthermore, MAT is time consuming, potentially hazardous to laboratory personnel, and difficult to standardize. According to the Leptospirosis Report of CDC,[[10]] the two cases presented above had clinical symptoms consistent with leptospirosis and seroconversion in recovery stage. So, they were confirmed cases of leptospirosis infection.

The natural history of human leptospiral infection varies widely. Human leptospiral infection can cause a subclinical illness, or may be mistaken for influenza.[[11]] Alternatively, severe infections are characterized by acute renal and liver failure, and shock. Typical initial symptoms include fever, headache, myalgia, rigor, nausea, and vomiting. In about half of the infected patients the fever develops abruptly, occasionally exceeding 40°C, and frequently is accompanied by severe and unremitting headache and abdominal pain.[[1]] The differential diagnosis of leptospirosis should include malaria, dengue fever, influenza, acute schistosomiasis, enteric fever, rickettsial disease, cholera, and viral hemorrhagic fevers. Leptospirosis usually presents as one of two clinically recognizable syndromes. The milder anicteric form (90% of cases) rarely results in death, while the fulminant icteric form, known as Weil's syndrome, has an associated mortality of 10%. In the anicteric form, there are two stages of disease; namely the septicemic phase and the immune phase. However, in Weil's syndrome these two phases are not well demarcated. During the septicemic phase, symptoms may persist from 4 to 7 days and circulating collapse may occur.[[12]] Also, during this septicemic phase, leptospirosis can be isolated from blood, CSF, and most tissue, including aqueous humor. The second phase, known as immune phase, may or may not occur after 1 to 2 days of defervescence. The onset of this stage coincides with the appearance of IgM and persists from 4 to 30 days. Leptospirosis disappears from the blood and CSF, but remain in the kidneys (and urine) and aqueous humor. Leptospiruria can persist in humans for 1–3 weeks, and in some animals leptospires can be shed chronically.[[13]] CNS involvement is common in patients with leptospirosis, although the pathogenesis of meningeal irritation is obscure. Leptospires enter the CSF in the early septicemic phase of the illness, but little evidence exists of inflammatory response in the CSF.[[1]] The case 1 presented here had headache before losing consciousness, physical examination revealed no neck rigidity, Kernig's sign or Brudzinski's sign. Furthermore, CSF study showed aseptic meningitis with mild pleocytosis, which is compatible with the presentation of leptospiral meningitis.[[14]] Meanwhile, the case 2 had acute icteric hepatitis and oligoric renal failure. The hepatitis and renal failure improved after adequate infection control.

Renal abnormalities in leptospiral infection induce tubulointerstitial damage, which is manifested by tubular cell necrosis, foci of vasculitis, and lymphocytic infiltrates. The presentation of renal pathology in case 1 was compatible with mild tubulointerstitial nephritis. The renal involvement leads to hypoxia and hypoperfusion, manifested by a decreased glomerular filtration rate, elevated ratio of BUN to Cr, inability to concentrate urine, and hypokalemia.[[15]] To localize the renal tubular defect, tubular clearance tests were performed in the recovery phase of acute renal failure, which included: bicarbonate infusion test, furosemide test, and thiazide test. Polyuria and hypokalemia appear frequently with an elevated urinary fractional excretion of potassium.[[16]] The cause of hypokalemia is thought to be due to proximal tubular lesions. The Leptospira interrogans endotoxin may bind to the Na⁺–K⁺ ATPase along the nephron and induce inhibition on the Na⁺–K⁺ ATPase.[[17]] Moreover, the increase in sodium and water delivery to the distal tubule may enhance potassium secretion. Previous report[[5]] has revealed a defect on the proximal tubule in Leptospira borgpetersenii serogroup ballum infection. The case 1 reported here and the other report[[18]] showed injuries on thick ascending limb in Leptospira shermani infection. Consequently, the leptospiral endotoxin may attack miscellaneous nephron segments, depending on different serotypes.

Yang et al. added outer membrane protein extract from Leptospira shermani to a model of cultured medullary thick ascending limb of loop of Henle (mTAL) cells. This addition induced a significant nuclear DNA binding of the NF-κB transcription factor. Moreover, two days after adding the outer membrane protein extract, the expression of inducible nitric oxide (iNOS) mRNA, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNF-α) all increased. Therefore, L. shermani infection may cause mTAL cell damage and inflammation through the NF-κB–associated pathway.[[19]]