ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol., 22 November 2021

Sec. Clinical and Diagnostic Microbiology and Immunology

Volume 11 - 2021 | https://doi.org/10.3389/fcimb.2021.770551

Pulmonary Mucormycosis as the Leading Clinical Type of Mucormycosis in Western China

  • 1. Center of Infectious Disease, West China Hospital, Sichuan University, Chengdu, China

  • 2. Radiology Department, West China Hospital, Sichuan University, Chengdu, China

Abstract

The aim was to better understand the clinical characteristics of patients with mucormycosis in western China. We retrospectively investigated the clinical, laboratory, radiological and treatment profiles of mucormycosis patients during a 10-year period (2010–2019). As a result, 59 proven mucormycosis were enrolled in this study. It was found that 52.5% of patients had worse clinical outcomes. Pulmonary mucormycosis (PM) was the most common clinical manifestation. The most frequent risk factor was diabetes mellitus (38, 64.4%) for mucormycosis patients. Cough (43, 93.5%), fever (24, 52.2%) and hemoptysis/bloody phlegm (21, 45.7%) were the most common manifestations of PM. There were no differences in clinical manifestations, risk factors and laboratory tests between different clinical outcome groups (P>0.05). Lymph node enlargement (30, 65.2%), patchy shadows (28, 60.9%), cavitation (25, 53.3%) and bilateral lobe involvement (39, 84.8%) were the most common on chest CT. Nodule was more common in good outcome group (P <0.05). A total of 48 cases (81.4%) were confirmed by histopathological examination, 22 cases (37.3%) were confirmed by direct microscopy. PM patients were treated with amphotericin B/amphotericin B liposome or posaconazale had better clinical outcomes (P <0.05). In conclusion, PM was the most common clinical type of mucormycosis in China. Diabetes mellitus was the most common risk factor. PM has diverse imaging manifestations and was prone to bilateral lobes involvement. Early diagnosis and effective anti-mucor treatment contribute to successful treatment.

Introduction

Mucormycosis is a rare, emerging and opportunistic fungal infection with high morbidity and mortality caused by filamentous fungi of the Mucoraceae family, order Mucorales. Mucorales fungi are ubiquitous in nature. Humans are infected mainly by inhaling sporangiospores, occasionally through the ingestion of contaminated food or traumatic inoculation (Prakash and Chakrabarti, 2019; Shariati et al., 2020). The prevalence of mucormycosis varies between developing and developed countries, ranging from 0.01 to 14 per 100 000 population in Europe and India (Bitar et al., 2009; Chakrabarti and Singh, 2014; Ruhnke et al., 2015). With the growth of the number of immunocompromised patients, increased awareness and development of diagnostic techniques, the incidence of mucormycosis is rising (Prakash et al., 2019). According to clinical presentations, mucormycosis is mainly classified as rhino-orbito-cerebral, pulmonary, cutaneous, gastrointestinal and disseminated types (Skiada et al., 2020). The common risk factors of mucormycosis are diabetes, hematological malignancy, use of corticosteroids or immunosuppressants, and trauma (Petrikkos et al., 2014; Jeong et al., 2019). However, the main cause of mucormycosis also varies in different countries. Hematological malignancies are the main cause in countries with high income, while diabetes mellitus (DM) or trauma are the main cause in developing countries (Chakrabarti and Singh, 2014). Diagnosis of mucormycosis is challenging because of the low sensitivity and specificity of clinical diagnostic methods (Skiada et al., 2018).

The mortality of mucormycosis remains high, it may be related to delayed diagnosis, high cost of managing mucormycosis and limited treatment options (Skiada et al., 2018). Previous studies on the characteristics of mucormycosis have been conducted mainly in America, Europe and India (Prakash and Chakrabarti, 2019). Data about mucormycosis from China is sparse. The causative agents of mucormycosis vary with different geographical locations (Prakash and Chakrabarti, 2019), and the epidemiology, the clinical disease pattern of mucormycosis vary from country to country.

To better understand the clinical characteristics of patients with mucormycosis in China, in this retrospective study, we compared the demographic features, clinical presentations, laboratory data, radiographic findings and therapeutic strategies in mucormycosis patients with different clinical outcomes who were admitted to a university hospital from Jan 2010 to Dec 2019 in western China.

Materials and Methods

Patients

From Jan 2010 to Dec 2019, the patients with a diagnosis of mucormycosis at hospital discharge were retrospectively reviewed in West China Hospital, Sichuan University, a 4,300-bed academic tertiary hospital in Chengdu, China. According to the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) criteria and previous references (De Pauw et al., 2008; Petrikkos et al., 2014; Skiada et al., 2018), inclusion in the final study group required the diagnosis of proven mucormycosis as defined as follows: (1) age ≥ 14 years; (2) clinical manifestations and radiographic findings consistent with mucormycosis; and (3) histological presence of mucormycosis in tissue specimens, and/or broad-based, ribbon-like, non-septate hyphae with right-angle branching filamentous fungi on direct microscopy of clinical specimens, and/or Mucorales species cultured from clinical specimens. Based on clinical presentation and the involvement of the body sites, rhino-orbital-cerebral, pulmonary, cutaneous and disseminated mucormycosis were classified (Jeong et al., 2019). The following data of demographic information, underlying diseases, use of corticosteroid or immunosuppressive agent, clinical manifestations, laboratory data, radiologic findings, diagnostic procedures, therapeutic strategies and clinical outcomes at 90 days were collected.

The study was approved by the Ethics Committee of West China Hospital, Sichuan University. Because all the data in this study were routinely obtained, written informed consent was waived.

Laboratory Studies

Laboratory tests including complete blood count, blood biochemistry, procalcitionin (PCT), C-reactive protein, T lymphocyte subset, HIV testing, serum (1,3)-beta-D-glucan test (BDG test), and galactomannan test (GM test) were performed. Clinical samples (including blood, sputum, secretions, urine) were aseptically collected and cultured under aerobic or anaerobic conditions. Bacterial species were isolated and identified using MicroScan WalkAway-96 System (Siemens, USA). Fungal culture was performed on Sabouraud dextrose agar (SDA) and incubated at 30°C. All the items were performed in the Department of Laboratory Medicine of our hospital.

Radiological Assessment

Imaging examinations such as chest computed tomography (CT), abdominal CT, fibroptic bronchoscopy were performed at the discretion of the treating physicians. The CT scans were performed using 64-row multi-slice spiral CT scanner (SOMATOM definition AS+, Siemens) in our hospital. All images were reviewed independently by two experienced radiologists. For patients with PM, chest CT findings including nodule, mass, cavity, patchy consolidation, ground glass opacity, reversed halo sign, lymph node enlargement, pleural effusion and the distribution of the lesion in the lungs were recorded.

Treatment Strategies and Clinical Outcomes

The patients with mucormycosis were treated with amphotericin B (AmB, 0.5-1 mg/kg per day) (North China Pharmaceutical Co., Ltd., China) or amphotericin B liposome (LAmB, 3-6 mg/kg per day) in accordance with the drug instructions, guidelines (Skiada et al., 2013) and patient tolerance. Posaconazole oral suspension (40mg/ml, 10ml, twice daily) (Patheon Inc, Whitby, ON, Canada) was used in patients who have contraindications to amphotericin B or who cannot tolerate the side effects of amphotericin B like reduced kidney function, electrolyte imbalances, nausea and vomiting. The treatment duration was determined by the treating physicians according to the patient’s treatment response and the size of the focus. Management of patients with diabetes included dietary guidance, tight glucose control with insulin and/or hypoglycemic drugs, multiple flash glucose monitoring daily and treatment of complications. A multidisciplinary consulting team, including diabetes, infectious disease, nutrition, wound therapy, surgery, clinical microbiology, and clinical pharmacy, that offered specialist advice, on-going management. Other underlying diseases of these patients such as immune system disease, chronic lung disease were treated normally and systematically. For bacterial co-infection patients, empirical or targeted antimicrobial therapy were given. Clinical outcomes of patients with mucormycosis were evaluated at 90 days after diagnosis. According to clinical manifestations, laboratory findings and image changes, their clinical outcomes were divided into good and worse outcome. Death or disease progression or persistence were classified as worse outcome. The continuous improvement of clinical symptoms and imaging findings were classified as good outcome.

Statistical Analysis

Statistical analyses were performed using IBM SPSS Statistics for Windows v.26.0 (IBM Corp., Armonk, NY, USA). The Shapiro-Wilk normality test was used to test the normality of all quantitative variables. Continuous variables with normal distribution were presented as mean± standard deviation (SD) and compared by Student’s t-test. The relationship between categorical variables was assessed using Chi-square test or Fisher’s exact test. A two-tailed P value lower than 0.05 was considered statistically significant.

Results

Demographic Characteristics and Clinical Outcomes of Mucormycosis Patients

A total of 68 patients with mucormycosis were admitted to our hospital from January 2010 to December 2019, 59 of whom with proven mucormycosis (mean age 54.75 ± 14.72 years; 44 males) were enrolled in this retrospective study. Pulmonary mucormycosis (PM) was the most commonly observed manifestation (46/59, 78.0%), followed by rhino-orbital-cerebral (9/59, 15.3%) and disseminated mucormycosis (3/59, 5.0%). There was only one case of cutaneous mucormycosis. These patients were classified as pulmonary type and other type mucormycosis based on clinical type. The demographic and clinical outcomes of these patients were summarized in Table 1. The ages of patients with PM was higher than that of patients with non-pulmonary mucormycosis (P=0.015). The most frequent underlying disease was diabetes mellitus (38, 64.4%) for mucormycosis patients. More patients with PM had diabetes mellitus than patients with non-pulmonary mucormycosis (P=0.027). A total of 31 mucormycosis patients (52.5%) had worse clinical outcomes, clinical outcome was not obviously different between the two groups (P>0.05).

Table 1

VariablesClinical typeP-value
All (N = 59)Pulmonary type (N = 46)Other type (N = 13)
Male44 (74.6)35 (76.1)9 (69.2)0.616
Age (years) (mean ± SD)54.75 ± 14.7257.41 ± 12.4045.31 ± 18.640.015*
Underlying diseases or risk factors
Diabetes mellitus38 (64.4)33 (71.7)5 (38.5)0.027*
Immune system disease2 (3.4)1 (2.2)1 (7.7)0.395
Corticosteroid medication or immunosuppressive drugs4 (6.8)3 (6.5)1 (7.7)1.000
Hematological malignancy3 (5.1)1 (2.2)2 (15.4)0.119
Solid tumor2 (3.4)2 (4.3)0 (0.0)1.000
Chronic kidney diseases3 (5.1)3 (6.5)0 (0.0)1.000
Chronic lung disease8 (13.6)7 (15.2)1 (7.7)0.671
Chronic liver disease2 (1.7)1 (2.2)1 (7.7)0.395
Truma2 (3.4)1 (2.2)1 (7.7)0.395
None8 (13.6)6 (13.0)2 (15.4)1.000
Co-infection of other pathogens
Bacteria42 (71.2)32 (69.6)10 (76.9)0.738
Other fungi16 (23.7)14 (30.4)2 (15.4)0.481
Clinical outcome
Good outcome28 (47.5)23 (50.0)5 (38.5)0.462
Worse outcome31 (52.5)23 (50.0)8 (61.5)

Demographic and clinical outcomes in patients with mucormycosis.

*P < 0.05.

Demographic and Clinical Characteristics in Patients With PM

Demographic and clinical features of PM patients with different clinical outcomes were shown in Table 2. The most common clinical symptoms of PM patients were cough (43, 93.5%), fever (24, 52.2%) and hemoptysis/bloody phlegm (21, 45.7%). Diabetes mellitus (33, 71.7%) was the most frequent underlying disease. There were no significant difference in the gender, age, clinical symptoms and underlying diseases beween good and worse outcome group (P>0.05). For laboratory results, there was no significant difference between the two groups (P > 0.05).

Table 2

VariablesAll (N = 46) (n,%)Good outcome (N = 23) (n,%)Worse outcome (N = 23) (n,%)P-value
Male35 (76.1)5 (21.7)6 (26.1)0.288
Age57.41 ± 12.4056.00 ± 13.4458.82 ± 11.380.446
Presenting symptoms and signs
Fever24 (52.2)13 (56.5)11 (47.8)0.768
Cough43 (93.5)21 (91.3)22 (95.7)1.000
hemoptysis or bloody phlegm21 (45.7)9 (39.1)12 (52.2)0.554
Chest pain7 (15.2)2 (8.7)5 (21.7)0.414
Shortness of breath14 (30.4)9 (39.1)5 (21.7)0.200
Underlying diseases or risk factors
Diabetes mellitus33 (71.7)16 (69.6)17 (73.9)1.000
Immune system disease1 (2.2)0 (0.0)1 (4.3)1.000
Corticosteroid medication or immunosuppressive drugs3 (6.5)2 (8.7)1 (4.3)1.000
Hematological malignancy1 (2.2)1 (4.3)0 (0.0)1.000
Solid tumor2 (4.3)0 (0.0)2 (8.7)0.489
Chronic kidney diseases3 (6.5)2 (8.7)1 (4.3)1.000
Chronic lung disease7 (15.2)4 (17.4)3 (13.0)1.000
Chronic liver disease1 (2.2)1 (4.3)0 (0.0)1.000
Truma1 (2.2)1 (4.3)0 (0.0)1.000
None6 (13.0)4 (17.4)2 (8.7)0.665
Laboratory data
White blood cell (× 109/L)9.13 ± 6.849.58 ± 9.028.69 ± 3.760.665
Neutrophil (%)71.96 ± 12.2474.42 ± 12.1169.38 ± 12.100.170
Lymphocyte (× 109/L)1.48 ± 0.671.35 ± 0.601.62 ± 0.730.180
Eosinophil (× 109/L)0.33 ± 1.170.48 ± 1.460.19 ± 0.260.397
Mononuclear cell (× 109/L)0.49 ± 0.230.47 ± 0.260.50 ± 0.200.539
Procalcitionin (ng/mL)0.21 ± 0.490.29 ± 0.660.12 ± 0.130.289
C-reactive protein (mg/L)70.31 ± 87.9466.75 ± 97.4073.17 ± 82.080.831
Eerythrocyte sedimentation rate (mm/h)55.23 ± 24.0649.00 ± 24.6460.42 ± 23.310.278
CD4+ T lymphocyte (%)36.94 ± 10.3337.32 ± 8.0036.55 ± 12.540.771
CD8+ T lymphocyte (%)31.61 ± 9.4932.92 ± 8.1730.30 ± 10.800.475
CD4/CD8 ratio1.36 ± 0.771.23 ± 0.401.48 ± 1.010.409
CD4+ T lymphocyte (cells/μl)565.45 ± 288.69419.83 ± 92.04740.2 ± 357.470.062
CD8+ T lymphocyte (cells/μl)396.82 ± 176.78338.50 ± 45.12466.80 ± 253.690.250
Co-infecting agent
Bacteria25 (54.3)12 (52.2)13 (56.5)1.000
Virus2 (4.3)1 (4.3)1 (4.3)1.000
Fungi18 (39.1)10 (43.5)8 (34.8)0.763

Demographic and clinical characteristics in patients with pulmonary mucormycosis.

Findings of CT Scan in Patients With PM

The chest CT features of patients with PM were diverse, as shown in Figure 1. The detail of chest CT findings in these patients were shown in Table 3. The most common manifestations were lymph node enlargement (30, 65.2%), patchy shadows (28, 60.9%), cavitation (25, 53.3%) and nodules (24, 52.2%). Nodule was more common in good outcome group than in worse outcome group (P <0.05). Lymph node enlargement were more common in patients with worse outcome (P<0.05). Bilateral lungs were involved in 84.8% (39/46) of patients, with the left lower lobe (20, 43.5%) and right lower lobe (18, 39.1%) most commonly involved. There was no significant difference in the lobe of lesion distribution between the two groups (P>0.05). There were 13 patients with Mucor and Aspergillus co-infection and 1 patient with lung cancer. Based on imaging findings, 12 patients were suspected to be tumors, and 2 patients were suspected to be aspergillosis in the absence of concomitant Aspergillus. Figure 2 showed the changes of chest CT lesions during the follow-up of a patient with pulmonary fungal infection (Mucor with Aspergillus).

Figure 1

Table 3

MorphologyAll (N = 46) (n,%)Good outcome (N = 23) (n,%)Worse outcome (N = 23) (n,%)P-value
Consolidation20 (43.5)9 (39.1)11 (47.8)0.767
Nodule24 (52.2)16 (69.6)8 (34.8)0.038*
Ground-glass opacity7 (15.2)5 (21.7)2 (8.7)0.414
Mass15 (32.6)8 (34.8)7 (30.4)1.000
Cavitation25 (53.3)10 (43.5)15 (65.2)0.139
Patchy shadow28 (60.9)14 (60.9)14 (60.9)1.000
Fibrosis17 (37.0)8 (34.8)9 (39.1)1.000
Pleural effusion22 (47.8)11 (47.8)10 (43.5)1.000
Pleural thickening17 (37.0)6 (26.1)11 (47.8)0.221
Lymph node enlargement30 (65.2)11 (47.8)19 (82.6)0.029*
Reversed halo sign5 (10.9)2 (8.7)3 (13.0)1.000
Lobe of lesion distribution
Left upper lobe12 (26.1)5 (21.7)7 (30.4)0.738
Left lower lobe20 (43.5)11 (47.8)9 (39.1)0.767
Right upper lobe12 (26.1)7 (30.4)5 (21.7)0.738
Right middle lobe11 (23.9)8 (34.8)3 (13.0)0.165
Right lower lobe18 (39.1)8 (34.8)10 (43.5)0.763
Bilateral involvement39 (84.8)20 (87.0)19 (82.6)1.000

Chest CT findings of proven patients with pulmonary mucormycosis .

*P < 0.05.

Figure 2

Diagnostic Procedures and Treatment Strategies

Of the 59 proven patients with mucormycosis, 48 cases (81.4%) were confirmed by histopathological examination, 22 cases (37.3%) were confirmed by direct microscopy. There was no significant difference in the diagnostic procedures between the two groups (P>0.05). A total of 47 patients (79.7%) received treatment. Treatment strategies for these patients with mucormycosis include antifungal drugs, surgery, or both. Most patients (38/59, 64.4%) were treated with amphotericin B/LAmB. More patients with PM were treated with AmB/LAmB (P=0.006) or posaconazale (P=0.004) in good outcome group than in worse outcome group.

For patients with PM, only 3 patients were treated with surgery and LAmB, but there was no statistical difference in clinical outcome (P>0.05). The most common adverse events of AmB/LAmB included renal insufficiency (16/42, 38.1%) and hypokalemia (9/42, 21.4%) in this study. The severity of all adverse events were mild to moderate (grade 1-2) according to the US National Cancer Institute Common Toxicity Criteria (NCI-CTC) (US, National Cancer Institute, 2017). The adverse reaction ratio of AmB/LAmB has not statistical difference between the two groups (P>0.05). As shown in Table 4.

Table 4

Diagnostic methodAll (N = 59) (n,%)Good outcome (N = 28) (n,%)Worse outcome (N = 31) (n,%)P-value
Cluture13 (22.0)7 (25.0)6 (19.4)0.755
Direct microscopy22 (37.3)7 (25.0)15 (48.4)0.105
Histology48 (81.4)23 (82.1)25 (80.6)1.000
 Cluture positive only8 (13.6)5 (17.9)3 (9.7)0.458
 Direct microscopy positive only2 (3.4)1 (3.6)1 (3.2)1.000
 Histology positive only25 (52.4)14 (50.1)11 (35.5)0.260
 Cluture+histology4 (6.8)2 (7.1)2 (6.5)1.000
 Direct microscopy+histology19 (32.2)6 (21.4)13 (41.9)0.105
 Cluture+Direct microscopy1 (1.7)0 (0.0)1 (3.2)1.000
BDG test3 (5.1)1/24 (4.2)2/25 (8.0)1.000
GM test3 (5.1)2/20 (10.0)1/20 (5.0)1.000
Therapeutic strategies
PulmonaryAll
(N=46) (n,%)
Good outcome
(N=23) (n,%)
Worse outcome
(N=23) (n,%)
P-value
AmB/LAmB28 (60.9)19 (82.6)9 (39.1)0.006*
Posaconazale11 (23.9)10 (43.5)1 (4.3)0.004*
LAmB+Surgery3 (6.5)1 (4.3)2 (8.7)1.000
untreated11 (23.9)0 (0.0)11 (47.8)0.000*
Rhino-orbito-cerebralAll
(N=9) (n,%)
Good outcome
(N=3) (n,%)
Worse outcome
(N=6) (n,%)
P-value
AmB/LAmB7 (77.8)2 (66.7)5 (83.3)1.000
Posaconazale1 (11.1)0 (0.0)1 (16.7)1.000
AmB+Surgery1 (22.2)1 (33.3)0 (0.0)0.333
DisseminatedAll
(N=3) (n,%)
Good outcome
(N=1) (n,%)
Worse outcome
(N=2) (n,%)
P-value
AmB2 (66.7)1 (100.0)1 (50.0)NA
untreated1 (33.3)0 (0.0)1 (50.0)NA
CutaneousAll
(N=1) (n,%)
Good outcome
(N=1) (n,%)
Worse outcome
(N=0) (n,%)
P-value
AmB+Surgery1 (100.0)0 (100.0)0 (0.0)NA
Adverse reactions of AmB/LAmB
PulmonaryAll
(N=31) (n,%)
Good outcome
(N=20) (n,%)
Worse outcome
(N=11) (n,%)
P-value
Hypokalemia7 (22.6)5 (25.0)2 (18.2)1.000
Renal insufficiency11 (35.5)8 (40.0)3 (27.3)0.698
Phlebophlogosis1 (3.2)1 (5.0)0 (0.0)1.000
Allergic reaction1 (3.2)1 (5.0)0 (0.0)1.000
Gastrointestinal toxicity4 (12.9)2 (10.0)2 (18.2)0.601
Cardiotoxicity3 (10.7)2 (10.0)1 (9.1)1.000
Rhino-orbito-cerebralAll
(N=8) (n,%)
Good outcome
(N=3) (n,%)
Worse outcome
(N=5) (n,%)
P-value
Hypokalemia1 (1.3)0 (0.0)1 (20.0)NA
Renal insufficiency4 (50.0)3 (100.0)1 (20.0)NA
DisseminatedAll
(N=2) (n,%)
Good outcome
(N=1) (n,%)
Worse outcome
(N=1) (n,%)
P-value
Hypokalemia1 (50.0)0 (0.0)1 (100.0)NA
Renal insufficiency1 (50.0)1 (100.0)0 (0.0)NA
Gastrointestinal toxicity1 (50.0)0 (0.0)1 (100.0)NA
Agranulocytosis1 (50.0)0 (0.0)1 (100.0)NA

Diagnostic procedures and treatment strategies for proven patients with mucormycosis .

AmB, amphotericin B; BDG test, (1,3)-beta-D-glucan test; GM test, galactomannan test; LAmB, liposomal amphotericin B.

*P < 0.05; NA, Not Applicable.

Discussion

Mucormycosis is rare, neglected, and associated with high mortality rates. The study found that 52.5% of patients with mucormycosis had poor clinical outcomes. Which is similar to previous research results (Jeong et al., 2019). PM was the most common form of mucormycosis, accounting for 78.0% of all the patients with mucormycosis. Although previous studies have reported that rhino-orbital mucormycosis was the most common clinical type (Patel et al., 2020), PM maybe more common in China (Peng et al., 2019). This study also found the most common underlying disease was diabetes mellitus. Previous studies have shown that PM mainly occurred in patients with hematological malignancies, while rhino-orbital mucormycosis mostly occurred in patients with diabetes mellitus (Skiada et al., 2011; Chakrabarti and Singh, 2014). However, our results were consistent with those from China (Peng et al., 2019). Perhaps because the number of diabetes patients in China is much larger than that of hematological malignancies (Liu et al., 2019; Khan et al., 2020), the underlying disease of more mucormycosis patients is diabetes. The high prevalence of diabetes in China and endemic mucor species different from other countries may also be the reasons for the high incidence of PM in diabetic patients in China. More detailed etiological studies of mucormycosis need to be done. We found the incidence of mucormycosis was tended to rise, which may be owing to the improvement of fungal diagnostic technology, health awareness and the visiting rate. In addition, diabetes incidence is on the rise worldwide, especially in China and India (Khan et al., 2020), which may be the reason for the increase in the incidence of mucormycosis in China.

For PM, the most common clinical symptoms were cough, fever, and hemoptysis/bloody phlegm. This result was similar to some previous studies (Skiada et al., 2011; Peng et al., 2019). Molecular-based assays can help to identify different fungal species and it can be used as a supplement to conventional diagnostic methods (Machouart et al., 2006; Springer et al., 2016). The study also found that laboratory results were not associated with patient outcomes. Most previous studies have not found a correlation between laboratory results and clinical outcomes in patients with mucormycosis (Patel et al., 2020; Son et al., 2020), and only a few studies have found that neutropenia may be associated with increased mortality (Spellberg et al., 2012). Neutropenia was not found in our patients with PM, it might not be an important risk factor for mortality in these patients.

The most frequent imaging findings of PM were patchy shadows, cavitation and pulmonary nodules in this study. According to the imaging findings, PM might be misdiagnosed as tumor or pulmonary aspergillosis. Nodule was more common in good outcome group. Lymph node enlargement were more common in patients with worse outcome. Many previous studies have found multiple nodules, reversed halo sign, and cavities associated with PM (McAdams et al., 1997; Marom and Kontoyiannis, 2011). Pulmonary nodules, halo sign and cavitation was also found in patients pulmonary invasive aspergillosis (Althoff Souza et al., 2006; Muldoon et al., 2016). The reversed halo sign has been considered an important clue to the diagnosis of PM, however, it has also been described in other pulmonary diseases, including invasive pulmonary aspergillosis, tuberculosis, organising pneumonia and malignancy (Sullivan and Rana, 2019). Therefore, early biopsy to establish the underlying cause is very important in patients with suspected pulmonary fungal infections.

Diagnosis of mucormycosis is challenging. In clinical practice, laboratory diagnosis of mucormycosis includes histopathology, direct examination and cultures (Skiada et al., 2020). Most patients in this study were diagnosed by histopathology. Many previous studies have also reported that histopathology was the main diagnostic method of mucormycosis (Prakash and Chakrabarti, 2019). In this study, Mucorales culture positive was found only in 13 patients. It was previously reported that the positive rate of Mucorales culture could reach 79% (Prakash and Chakrabarti, 2019). Which may be related to the low vigilance of doctors to invasive pulmonary mycosis and the absence of fungal culture for puncture specimens. More needs to be done to raise awareness of pulmonary mycosis among doctors.

In this study, twelve patients did not receive treatment and left the hospital against medical advice after diagnosis because of their critical condition and financial constraints. PM patients were treated with amphotericin B or posaconazole had better clinical outcomes, while untreated patients had poor outcomes. For rhino-orbito-cerebral and disseminated mucormycosis patients, there was no statistically significant difference in clinical outcome between different treatment strategies, which maybe related to the small number of cases. In addition, patients with rhino-orbito-cerebral mucormycosis who underwent surgery and antifungal therapy had better clinical outcomes. At present, treatment options for mucormycosis remain very limited. LAmB combined with surgery are strongly recommend as first-line therapy. Isavuconazole and posaconazole are also options as second-line agents (Cornely et al., 2019). For patients with PM, only 3 patients in this study were received pulmonary lobectomy, so no benefit of antifungal combined surgical treatment over antifungal therapy alone was observed. Bilateral lobe involvement occurred in 84.8% of patients in this study, which was similar to previous studies (Peng et al., 2019). Multifocal involvement limited the surgical options, early and effective antifungal therapy may be more important for patients with PM. The recommended combination of antifungal agents and surgical treatment as a treatment option for mucormycosis may be based on the presence of more rhino-orbito-cerebral mucormycosis in other countries. More researches may be needed to optimize treatment options for different types of mucormycosis. New treatment drugs or methods, such as combination of lipid amphotericin B and caspofungin or posaconazole, VT-1161, deferasirox in combination with a polyene, hyperbaric oxygen and so on, still deserve to be expected to improve clinical outcome (Skiada et al., 2018).

This study has some limitations. First, it was a retrospective observational study. Only some patients have complete follow-up data in our hospital, especially imaging data, and the follow-up of some patients could only be completed by telephone. Second, the detection rate of tissue culture was low, the pathological diagnosis was determined mainly by morphology and special staining. It is important to raise the awareness of doctors about fungal disease and the importance of tissue culture. Third, because mucormycosis is a relatively rare fungal disease in China (Liao et al., 2013), the number of cases in this study was limited. More larger-scale, multicenter studies of mucormycosis in the real world should be done.

Conclusions

The most common clinical type of mucormycosis in China was PM. The most common risk factor was diabetes mellitus. Diabetic patients with clinical manifestations of febrile and hemoptysis, CT findings of nodules, cavities and bilateral lung involvement should be vigilant against PM. Early diagnosis and effective anti-mucor treatment are very important to improve the prognosis of patients with mucormycosis.

Funding

This study was supported by Sichuan Province Science and Technology Support Program of China (grant number: 2021YFS0170), 1•3•5 project for disciplines of excellence-Clinical Research Incubation Project, West China Hospital, Sichuan University (grant number: 2021HXFH032).

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Statements

Data availability statement

The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding author.

Ethics statement

The studies involving human participants were reviewed and approved by Ethics Committee of West China Hospital, Sichuan University. Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.

Author contributions

XL and JQ conceived of and designed the study. JQ and XL collected, analysed or interpreted data. JQ wrote the draft. All authors read, revised and approved the final manuscript.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Summary

Keywords

mucormycosis, pulmonary mucormycosis, diabetes, clinical analysis, clinical outcome

Citation

Qu J, Liu X and Lv X (2021) Pulmonary Mucormycosis as the Leading Clinical Type of Mucormycosis in Western China. Front. Cell. Infect. Microbiol. 11:770551. doi: 10.3389/fcimb.2021.770551

Received

04 September 2021

Accepted

04 November 2021

Published

22 November 2021

Volume

11 - 2021

Edited by

Kai Huang, University of Texas Medical Branch at Galveston, United States

Reviewed by

Muhammad Usman Tariq, Abu Dhabi School of Management, United Arab Emirates; Valentina Giudice, University of Salerno, Italy; Dora Edith Corzo-Leon, University of Aberdeen, United Kingdom

Updates

Copyright

*Correspondence: Xiaoju Lv,

This article was submitted to Clinical Microbiology, a section of the journal Frontiers in Cellular and Infection Microbiology

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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