Severe leptospirosis in tropical Australia: Optimising intensive care unit management to reduce mortality

Severe leptospirosis in tropical and non-tropical areas: A comparison of two french, multicentre, retrospective cohorts

BACKGROUND

Leptospirosis is an anthropozoonosis that occurs worldwide but is more common in tropical regions. Severe forms may require intensive care unit (ICU) admission. Whether the clinical patterns and outcomes differ between tropical and non-tropical regions with similar healthcare systems is unclear. Our objective here was to address this issue by comparing two cohorts of ICU patients with leptospirosis managed in mainland France and in the overseas French department of Réunion, respectively.

METHODOLOGY/PRINCIPAL FINDINGS

We compared two retrospective cohorts of patients admitted to intensive care for severe leptospirosis, one from Reunion Island in the Indian Ocean (tropical climate) and the other from metropolitan France (temperate climate). Chi-square and Student's t tests were used for comparisons. After grouping the two cohorts, we also performed multiple correspondence analysis and hierarchical clustering to search for distinct clinical phenotypes. The Réunion and Metropolitan France cohorts comprised 128 and 160 patients respectively. Compared with the Réunion cohort, the metropolitan cohort had a higher mean age (42.5±14.1 vs. 51.4±16.5 years, p<0.001). Severity scores, length of stay and mortality did not differ between the two cohorts. Three phenotypes were identified: hepato-renal leptospirosis (54.5%) characterized by significant hepatic, renal and coagulation failure, with a mortality of 8.3%; moderately severe leptospirosis (38.5%) with less severe organ failure and the lowest mortality rate (1.8%); and very severe leptospirosis (7%) manifested by neurological, respiratory and cardiovascular failure, with a mortality of 30%.

CONCLUSIONS/SIGNIFICANCE

The outcomes of severe leptospirosis requiring ICU admission did not differ between tropical and temperate regions with similar healthcare access, practices, and resources, despite some differences in patient characteristics. The identification of three different clinical phenotypes may assist in the early diagnosis and management of severe leptospirosis.

Pulmonary haemorrhage as a frequent cause of death among patients with severe complicated Leptospirosis in Southern Sri Lanka

BACKGROUND

Leptospirosis is a tropical disease associated with life threatening complications. Identifying clinical and investigation-based parameters that predict mortality and morbidity is vital to provide optimal supportive care.

METHODS

We conducted an observational study in an endemic setting, in the southern Sri Lanka. Consecutive patients having complicated leptospirosis were recruited over 18 months. Clinical, investigational and treatment data were collected and the predictors of mortality were analysed.

RESULTS

Out of 88 patients having complicated leptospirosis, 89% were male. Mean age was 47yrs (±16.0). Among the total major complications 94.3% had acute kidney injury, 38.6% pulmonary haemorrhages, 12.5% fulminant hepatic failure, 60.2% hemodynamic instability and 33% myocarditis. An acute significant reduction of haemoglobin (Hb) was observed in 79.4% of patients with pulmonary haemorrhage. The mean of the highest haemoglobin reduction in patients with pulmonary haemorrhage was 3.1g/dL. The presence of pulmonary haemorrhage (PH) and hemodynamic instability within first 48 hours of admission significantly predicted mortality (p<0.05) in severe leptospirosis. Additionally, within first 48 hours of admission, elevated SGOT (AST), presence of atrial fibrillation, presence of significant haemoglobin reduction, higher number of inotropes used, prolonged shock, invasive ventilation and admission to ICU significantly predicted mortality. Out of major complications during the first week after admission, pulmonary haemorrhage and fulminant hepatic failure (FHF) combination had significant adjusted odds of mortality (OR = 6.5 and 4.8, p<0.05). Six patients with severe respiratory failure due to PH underwent ECMO and four survived. The overall mortality in complicated leptospirosis was 17%. In PH and FHF, the mortality rate was higher reaching 35.4% and 54.5%, respectively.

CONCLUSIONS

Within first 48 hours of admission, major complications such as pulmonary haemorrhage and haemodynamic instability and other parameters such as atrial fibrillation, acute haemoglobin reduction, elevated SGOT level could be used as early parameters predictive of mortality in severe leptospirosis. PH and FHF during the first week of admission in leptospirosis are associated with high morbidity and mortality requiring prolonged ICU care and hospitalisation. Above parameters could be used as parameters indicating severity for triaging and intensifying treatment. Using ECMO is a plausible treatment option in patients with severe pulmonary haemorrhage.

The efficacy and safety of a shortened duration of antimicrobial therapy for group A Streptococcus bacteremia

OBJECTIVES

To determine if shorter courses of antibiotic therapy for group A Streptococcus (GAS) bacteremia are associated with excess mortality.

METHODS

In this retrospective study of consecutive cases of GAS bacteremia in tropical Australia, the duration of antibiotic therapy was correlated with 90-day all-cause mortality.

RESULTS

There were 286 episodes of GAS bacteremia; the patients' median (interquartile range) age was 60 (48-71) years and 169/286 (59.1%) patients identified as an Indigenous Australian. There were 227/286 (79.4%) patients with a significant comorbidity. The all-cause 90-day mortality was 16/286 (5.6%); however, 12/16 (81.3%) patients died while still receiving their initial course of antibiotics and only 7/16 (43.8%) deaths were directly attributable to the GAS infection. After excluding patients who died while taking their initial course of antibiotics and those in whom the duration of therapy was uncertain, there was no difference in 90-day mortality between patients receiving ≤5 days of intravenous antibiotics and those receiving longer courses (1/137 [0.7%] vs 3/107 [2.8%], P-value = 0.32) nor in patients receiving ≤10 days of total therapy and those receiving longer courses (1/67 [1.5%] vs 3/178 [1.7%], P-value = 1.0).

CONCLUSION

Even among patients with significant comorbidity, shorter antibiotic courses for GAS bacteremia are not associated with excess mortality.

Limited Awareness of Melioidosis in High-risk Populations Despite an Increasing Incidence of the Disease in Far North Queensland, Australia

The incidence of melioidosis, an opportunistic infection caused by Burkholderia pseudomallei, has recently doubled in Far North Queensland (FNQ), Australia. This contrasts with the local burden of dengue, which is nearing elimination, and the stable incidence of leptospirosis. This questionnaire-based study assessed the awareness of melioidosis among people in FNQ with risk factors for the disease, using awareness of leptospirosis and dengue as comparators. There were 427 respondents; 361 (85%) reported one or more risk factors for melioidosis. Only 69 of 361 (19%) had heard of melioidosis compared with 301 of 361 (83%) who had heard of dengue (P < 0.001) and 137 of 361 (38%) who had heard of leptospirosis (P < 0.001). In FNQ, Australia, there is an increasing local incidence of melioidosis, but there is limited awareness of the disease among high-risk individuals. Greater community awareness of melioidosis is necessary to implement strategies to prevent disease and expedite the presentation of patients with this life-threatening infection.

The aetiology and clinical characteristics of cryptococcal infections in Far North Queensland, tropical Australia

Cryptococcal infections are an important cause of morbidity and mortality in tropical Australia. This retrospective audit was conducted to characterise the aetiology, temporospatial epidemiology, and clinical course of 49 cryptococcal infections in Far North Queensland between 1 January 1999 and 31 December 2019. Cryptococcus gattii was identified in 15/32 (47%) in whom it was possible to speciate the organism. Among these 15 patients, 13 (87%) had a rural residential address, 10 (67%) were Indigenous Australians and 11 (73%) presented during the May-November dry season. When compared to the 17 patients with Cryptococcus neoformans infection, patients with C. gattii were less likely to be immunocompromised (0/15 versus 8/17 (47%), p = 0.003). Neurosurgery was necessary in 5/15 C. gattii cases and 3/17 (18%) C. neoformans cases (p = 0.42). Outcomes were generally good with 42/49 (86%) cases—and 14/15 (93%) with C. gattii infection—surviving to hospital discharge. These positive outcomes are likely to be explained by the development of standardised treatment guidelines during the study period, low rates of comorbidity in the patients with C. gattii infection and access to liposomal amphotericin and neurosurgical support in the well-resourced Australian healthcare system.

Clinical profile, management and outcome of patients with leptospirosis during the times of COVID-19 pandemic: A prospective study from a tertiary care centre in South India

Leptospirosis is a rodent-borne acute febrile illness, classically seen after heavy rainfall and floods. This study aimed to describe the clinical profile, management strategies and outcome of patients with leptospirosis amidst the Coronavirus disease-2019 outbreak. A prospective study of adult patients with undifferentiated fever (5-15 days) was conducted in South India between October 2020 and February 2021. The demographic, clinical details, laboratory details, treatment and outcome of leptospirosis positive (based on serology) and negative patients were compared. A chisquare test was used for qualitative variables, while an independent t-test or Mann Whitney U test was used for continuous variables. Of the 206 patients with suspected acute febrile illness, a total of 63 patients were diagnosed with leptospirosis based on serology results. The median sequential organ failure assessment score was higher in those with leptospirosis (p<0.001). Myalgia, abdominal pain, jaundice, decreased urine output, myocarditis, and dialysis requirement were more common in patients with leptospirosis. Leucocytosis and raised procalcitonin/C-reactive protein were more common in patients with leptospirosis. The duration of stay and antibiotic consumption was higher in patients with leptospirosis. Acute febrile illness such as leptospirosis should be suspected in tropical areas with significant risk factors. The presence of conjunctival suffusion, hepatic and renal dysfunction should warrant a serology test for leptospirosis.

The Applicability of Commonly Used Severity of Illness Scores to Tropical Infections in Australia

Many patients with leptospirosis, melioidosis, and rickettsial infection require intensive care unit (ICU) admission in tropical Australia every year. The multi-organ dysfunction associated with these infections results in significantly elevated severity of illness (SOI) scores. However, the accuracy of these SOI scores in predicting death from these tropical infections is incompletely defined. This retrospective study was performed at Cairns Hospital, a tertiary-referral hospital in tropical Australia. All patients admitted to ICU with laboratory-confirmed leptospirosis, melioidosis, and rickettsial disease between January 1, 1999 and June 30, 2020, were eligible for the study. The ability of Acute Physiology and Chronic Health Evaluation (APACHE) II, APACHE III, Simplified Acute Physiology Scores (SAPS) II, and Sequential Organ Failure Assessment (SOFA) scores to predict death before ICU discharge was evaluated. Overall, 18 (12.1%) of the 149 included patients died: 15/74 (20.3%) with melioidosis, 2/54 (3.7%) with leptospirosis and 1/21 (4.8%) with rickettsial disease. However, the APACHE II, APACHE III, SAPS II, and SOFA scores significantly overestimated the case-fatality rate of all the infections; the disparity between the predicted and observed mortality was most marked in the cases of leptospirosis and rickettsial disease. Commonly used SOI scores significantly overestimate the case-fatality rate of melioidosis, leptospirosis, and rickettsial infections in Australian ICU patients. This may be at least partly explained by the unique pathophysiology of these infections, particularly leptospirosis and rickettsial disease. However, SOI scores may still be useful in facilitating the comparison of disease severity in clinical trials that examine patients with these pathogens.

Pathogenesis of Pulmonary Hemorrhagic Syndrome in Human Leptospirosis

Based on a previous study and by incorporating new knowledge, the goal of our study was to understand more fully the pathogenesis of hemorrhagic pneumonia of severe human leptospirosis, highlighting the onset of capillary lesions by Leptospira itself and/or its antigenic/toxic products acting on the endothelium and binding to cadherins. Both events lead to loss of endothelial integrity, alter permeability, cause rupture, and open intercellular junctions, contributing to the hemorrhagic phenomena associated with severe leptospirosis.

Leptospirosis in Intensive Care Unit

Tropical infections constitute 20 – 30% of intensive care unit (ICU) admissions in developing countries. Leptospirosis is a spectrum with mild form presenting as an acute febrile illness with jaundice, complicating in few as acute kidney injury (AKI), acute respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC), and multi-organ dysfunction syndrome (MODS). The poor prognostic markers are hemorrhagic ARDS, acute renal failure, DIC, severe metabolic acidosis, older age, chronic alcohol abuse, high SOFA score, and septic shock. The confirmatory diagnosis relies on antibody testing, such as microscopic agglutination test (MAT) and IgM ELISA, while the reverse transcription-polymerase chain reaction test being reserved for clinically suspected antibody negative cases. The spectrum of multi-organ involvement necessitates a complete hematological, biochemical workup, including electrocardiogram (ECG), chest X-ray, and two-dimensional echocardiography. Specific antimicrobial therapy consists of the following—benzylpenicillin, ceftriaxone, cefotaxime, and doxycycline. The reported mortality ranges from 6% to as high as 44%. Various ICU scores like SPiRO, THAI LEPTO score, and Faine's criteria have been useful in risk stratification. Optimizing intensive care treatment with appropriate antibiotics, lung protection ventilation strategies, strict fluid management, and if need be timely initiation of renal replacement therapy (RRT) helps in reducing mortality.

How to cite this article: Karnik ND, Patankar AS. Leptospirosis in Intensive Care Unit. Indian J Crit Care Med 2021;25(Suppl 2): S134–S137.

Circulating microtranscriptome profiles reveal distinct expression of microRNAs in severe leptospirosis

Biomarkers to predict the severity of leptospirosis are still lacking. This study aimed to identify and validate microRNAs in patients with severe leptospirosis, that could potentially be used as biomarkers for predicting an unfavorable outcome. Serum samples were collected from participants with definite diagnosis of leptospirosis. The participants were divided into two groups, non-severe and severe leptospirosis, as defined by the Specific Organ Sequential Organ Failure (SOFA) Score of more than two in any organ. Microtranscriptome analysis was performed using the NanoString miRNA Expression Assay. The expression level of candidate miRNAs was then validated by quantitative RT-PCR. Based on the NanoString, the microtranscriptome profile of the severe group was significantly different from that of the non-severe group. Upregulation of miR155-5p, miR362-3p, miR502-5p, miR601, miR1323, and miR630 in the severe group were identified, and further investigated. A total of 119 participants were enrolled in the validation cohort. Serum miR155-5p and miR630 levels were significantly higher in the severe group compared to the non-severe group. The combined use of miR155-5p or miR-630 with serum bicarbonate levels had an AUC of 0.79 (95%CI; 0.69-0.89, p<0.001) in identifying the severity of the disease. This data provides the first evidence that the microtranscriptome profiles of patients with severe leptospirosis were different from the non-severe group. Serum miR155-5p and miR630 levels might be novel biomarkers for identifying severe leptospirosis.

A cross-sectional pilot study to estimate the prevalence of and risk factors for leptospirosis in South-Western Victorian dairy herds, 2017

Leptospirosis is a zoonosis, found worldwide, affecting many species of animals. We conducted a cross-sectional study to estimate the prevalence of Leptospira borgpetersenii sv Hardjo and Leptospira interrogans sv Pomona in cattle in dairy herds in South-Western Victoria, Australia. Fifty-three herds were enrolled in the study. Urine samples were collected from 15 late-lactation cows in each herd. A questionnaire was provided to herd managers at the time of each herd visit, asking them to describe the methods they used for controlling leptospirosis, including vaccination. Urine samples were pooled at the herd level and tested for leptospira spp. using real time PCR. Urine samples from individual cows within the positive pooled samples were then tested for Leptospira Hardjo and Leptospira Pomona using qPCR. Four of the 53 herds showed positive leptospirosis results giving an apparent prevalence of 8 (95% CI 2-18) leptospira-positive herds per 100 herds at risk. Based on the 53 completed questionnaires, leptospirosis vaccination programs were not compliant with label directions in 36 of the 52 vaccinated herds: 69 (95% CI 55-81) of 100 herd managers that routinely vaccinated for leptospirosis did not comply with label directions. One herd was completely unvaccinated. Based on our findings, we estimate that approximately 10% of dairy farms in South-Western Victoria are likely to be infected with leptospirosis. While most herds are vaccinating for leptospirosis, most are not doing so according to label directions. We conclude that herd managers need to be better educated regarding leptospirosis vaccination programs.