**1. Introduction**

Urinary bladder cancer is the twelfth most frequent cancer worldwide—in 2020 more than 570,000 cases were diagnosed, and more than 200,000 deaths were caused by this disease [1]. The majority of cases are superficial (non-muscular invasive) cancer. Transurethral resection (TUR) of all lesions is the established standard managemen<sup>t</sup> [2]. Although noninvasive, the disease presents with a high rate of recurrence [2]. Instillations with an attenuated live strain of *Mycobacterium bovis*—bacillus Calmette-Guerin (BCG) are widely used as non-specific immunotherapy significantly reducing the recurrence rate in bladder cancer [3–5]. The standard treatment includes six weekly instillations of BCG after TUR, followed by maintenance treatment—three weekly instillations, every six months for three years [5]. The therapy is generally safe and well tolerated, although some side effects, both local and systemic, may be present [6]. The most frequent local complications are cystitis (27–95%), prostatitis (10%) and penile lesions (5.9%) [6]. Systemic complications are much

**Citation:** Lewandowska, K.; Lewandowska, A.; Baranska, I.; Klatt,M.; Augustynowicz-Kopec, E.; Tomkowski, W.; Szturmowicz, M. Severe Respiratory Failure Due to Pulmonary BCGosis in a Patient Treated for Superficial Bladder Cancer. *Diagnostics* **2022**, *12*, 922. https://doi.org/10.3390/ diagnostics12040922

Academic Editor: Stefano Gasparini

Received: 10 March 2022 Accepted: 6 April 2022 Published: 7 April 2022

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less prevalent and include fever (2.9%), tuberculous spondylitis (3.5%), granulomatous hepatitis (0.7–5.7%), reactive arthritis (0.5–5.7%), and mycotic aneurysms (0.7–4.6%) [6]. Pulmonary *M. bovis* BCG infection and sepsis are extremely rare and occur in 0.4% of patients [6].

There are two different hypotheses regarding the mechanisms of disseminated BCGrelated disease. It is postulated, that immunological reaction, i.e., granulomatous inflammation without the presence of living microorganisms plays a key role. On the other hand, occasionally positive cultures or positive genetic tests for *M. bovis* BCG are obtained, indicating the presence of active infection. Both mechanisms may coexist. In the biggest report presenting pooled data on BCG treatment complications, published between 1975 and 2013, no specific risk factors for BCG treatment side effects have been identified [7]. The higher mortality was related to older age (≥65 years), disseminated BCG infection and the presence of mycotic aneurysms [7]. The postulated role of immunosuppression has not been clearly confirmed [8] and the guidelines did not recommend different treatments for immunocompromised patients [5].

Identification of *M. bovis* BCG is not straightforward, since it belongs to the *Mycobacterium tuberculosis* complex (MTBC), a highly related mycobacterial species including *M. tuberculosis*, *M. bovis*, *M. africanum*, *M. microti* and *M. canettii* [9]. Live mycobacteria belonging to MTBC, secrete the product of *mpb64* gene—MPT64 protein. Rapid immune chromatography for the detection of the MPT64 protein is a simple and cost-effective method, distinguishing MTBC from non-tuberculous mycobacteria (NTM) [10]. However, some BCG strains have deletions or mutations in the *mpb64* gene. The presence of the *mpb64* gene encoding the MPT64 protein was found in the BCG-Moreau, BCG-Sweden, BCG-Birkhaug and BCG-Russia vaccine strains, whereas it was not found in the BCG-Danish, BCG-Pasteur, BCG-Glaxo, BCG-Tice strains [11]. Therefore, using a test detecting MPT64 protein for identification of the BCG strain with a deletion or mutation in the *mpb64* gene may lead to its misidentification as NTM [11].

The treatment of *M. bovis* infection is based on rifampin, isoniazid and ethambutol, using the typical doses as in tuberculosis patients [7]. In some cases, fluoroquinolones or aminoglycosides are used instead of one of the first line antituberculous drugs or as additional drugs [7,12]. The duration of treatment is usually six months if three antituberculous drugs are used and longer if one or two are replaced with fluoroquinolone [7,12,13]. In severe cases with respiratory failure, systemic corticosteroids are used [13]. The treatment outcome is usually good [7].

We present diagnostic and therapeutic problems concerning a 75-year-old male with severe respiratory failure in the course of pulmonary BCG infection caused by the *M. bovis* BCG strain that was MPT64-negative.

#### **2. Case Report**

A 75-year-old male, active smoker (40 pack-years), was admitted to the department of lung diseases in October 2021 due to three-week-long history of hemoptysis, left-sided pleuritic chest pain, general weakness, and fever. The patient was treated with BCG instillations due to superficial bladder cancer for three years, the last instillation was given a month before presentation. In March 2021 he underwent asymptomatic infection with SARS-CoV-2 (positive PCR test performed before an elective hospitalization). He had also a history of esophageal varices, chronic pancreatitis related to cholelithiasis treated with cholecystectomy and partial pancreatectomy, and partial post-traumatic splenectomy. He reported contact with tuberculosis from his father during his childhood. The patient worked as an academic and had no exposure to toxic materials or organic dusts. Before he was admitted to our hospital, he received a course of ciprofloxacin. Ambulatory computed tomography pulmonary angiography (CTPA) showed pulmonary arteries without emboli, emphysema of the lungs' and discreet nodular, reticular, and ground glass opacities in the peripheral parts of the lungs, which were suggestive of nonspecific interstitial pneumonia (NSIP).

On admission, the patient presented with dyspnea (respiratory rate 20/min), cachexia (body mass index-19) and generalized weakness. Body temperature was 37.5 ◦C. Percutaneous oxygen saturation (SpO2) on room air was 90%. On auscultation, diminished respiratory sounds were present over the whole lungs, with some bilateral crackles at the basal parts of the lungs. The liver was slightly enlarged.

Chest X-ray showed pulmonary emphysema, bilateral apical scaring, and some reticular and peribronchial lesions in the lower part of the left lung (Figure 1).

**Figure 1.** Posteroanterior chest X-ray showing pulmonary emphysema, bilateral apical scaring (arrows), and some reticular and peribronchial lesions in the lower part of the left lung (asterisk).

The BD SARS-CoV-2 BD MAX™ real-time RT-PCR test yielded a negative result. Laboratory blood tests revealed slightly decreased number of platelets (106 × 109/L, N: 130–400 × 109), elevated C-reactive protein (CRP) concentration (58.4 mg/L, N: <5 mg/L), N-terminal brain natriuretic pro-peptide (NT-proBNP) concentration (1558 pg/mL, N < 125 pg/mL) and Ddimer (2553 ng/mL, N: <500 ng/mL) as well as increased liver enzymes activity: aspartate aminotranspeptidase (AST) 80 U/L (N: <40 U/L), alkaline phosphatase (ALP) 347 U/L (N: 40–130 U/L) and gamma-glutamyl transpeptidase (GGTP) 218 U/L (N: <60 U/L). Arterial blood gases showed hypoxemia (PaO2 61.7 mmHg, N: 65–90 mmHg) with hypocapnia (PaCO2 30.5 mmHg, N: 35–45 mmHg) and respiratory alkalosis (pH 7.485, N: 7.35–7.45). An ultrasound scan of the abdomen revealed enlarged and high-density liver with uneven margins, suggesting liver cirrhosis. The provisional diagnosis of lower respiratory tract infection was established, and empirical antibiotic therapy (i.e., ceftriaxone), together with oxygen supplementation of 1 L/min through the nasal tube was started. The patient's clinical condition did not improve—the hemoptysis, low-grade fever and dyspnea persisted, with the need for increasing oxygen supplementation. The blood, sputum and urine cultures were negative.

Microscopic evaluation of the patient's sputum revealed no acid-fast bacilli (AFB), genetic testing (Xpert MTB/Ultra, Cepheid) for *Mycobacterium tuberculosis* complex (MTBC) was also negative. Taking into consideration the gradual worsening of the patient's condition, and persistent fever, fiberoptic bronchoscopy was performed, and the bronchial washings were sampled for microbiological tests, including MTB cultures. No signs of bleeding were visible during the procedure.

Antibiotic treatment was modified—ceftriaxone was withdrawn and meropenem with levofloxacin were started. A few days later, dyspnea increased suddenly. The cardiac arrhythmia was noted on physical examination, and the electrocardiogram (ECG) revealed atrial fibrillation. The sinus rhythm recovered spontaneously after a few hours. Despite that, the respiratory failure progressed, and oxygen delivery was gradually increased to maintain SpO2 above 90% (maximal oxygen flow was 15 L/min. through the face mask with an oxygen reservoir). A CTPA was repeated and excluded pulmonary emboli. Aortic atherosclerosis without aneurysm and bilateral hilar adenopathy was found. Massive bilateral ground glass opacities in the middle and lower parts of the lungs accompanied by parenchymal infiltrations and bronchial walls thickening were demonstrated (Figure 2)—the lesions progressed compared to the previous CTPA. This presentation suggested alveolar hemorrhage or infection.

**Figure 2.** Computed tomography (CT) scan of the chest showing bilateral hilar adenopathy (white arrows), massive bilateral ground glass opacities in the middle and lower parts of the lungs (black arrows) accompanied by parenchymal infiltrations (black asterisks) and bronchial walls thickening.

Meropenem was replaced with linezolid. Methylprednisolone 60 mg/day intravenously, was started as a rescue medication in a patient with severe respiratory failure, without an identified infectious agent. The patient's condition gradually improved. At the same time, the positive results of sputum and bronchial fluid cultures on liquid media become available—the acid-fast bacilli (AFB) were cultured.

Isolates of mycobacterial cultures on Mycobacteria Grow Indicator Tube (MGIT, Becton, Dickinson and Co., Sparks, NV, USA) liquid media were not producing MPT64 protein in the immunochromatographic test (Becton, Dickinson and Co., Sparks, NV, USA), indicating the presence of NTM in the patient's samples. However, stains of isolated cultures showed the serpentine cord formation, characteristic of MTBC [14] (Figure 3).

**Figure 3.** Ziehl-Nielsen-stained slide of mycobacterial cultures obtained on MGIT liquid media with characteristic serpentine cord factor (trehalose 6,6-dimicolate).

To resolve these conflicting results and identify the species of MGIT culture isolates, with morphologic features characteristic of MTBC, but showing negative MPT64 cards and negative MTBC PCR test results, identification was performed using a molecular test (GenoType MTBC VER 1.X, Hain Lifescience, Nehren, Germany). The test confirmed the presence of *Mycobacterium bovis* BCG strain. (Figure 4).

**Figure 4.** Result of molecular identification of MTBC strains by Hain Lifescience, Nehren, Germany. (**a**) *Mycobacterium tuberculosis*; (**b**) *Mycobacterium bovis;* (**c**) *Mycobacterium bovis* BCG.

Anti-tuberculous treatment was started (i.e., INH 300 mg/day, RMP 450 mg/day, and EMB 750 mg/day), systemic steroids continued. Further improvement was observed, oxygen therapy was decreased to 2 L/min through the nasal tube, and rehabilitation started. Due to the increase in AST activity to 155 U/L—INH was replaced with levofloxacin 500 mg/day. Final chemosensitivity tests showed the BCG strain resistance to INH, and levofloxacin remained in the treatment schedule. The liver function tests improved, CRP concentration normalized, and further treatment was uncomplicated. The follow-up high resolution computed tomography (HRCT) scan revealed significant partial resolution of ground glass opacities and parenchymal infiltrates, and decreased lymphadenopathy (Figure 5). The patient was discharged home with a three-drug anti-tuberculous regimen including RMP, EMB and levofloxacin. Prednisone was continued in diminishing doses. In the next few weeks, oxygen therapy was withdrawn, prednisone dose was decreased to 5 mg/day. Anti-tuberculous drugs were well tolerated. The treatment of bladder cancer with BCG instillations was withdrawn.

**Figure 5.** CT-scan of the chest after 3 weeks of anti-tuberculous treatment showing partial resolution of ground glass opacities (black arrow) and parenchymal infiltrates (asterisk), and decreased lymphadenopathy (white arrows).
