Case Report: Severe Community-Acquired Pneumonia in Réunion Island due to Acinetobacter baumannii

ABSTRACT. Acinetobacter baumannii (Ab) is a well-known nosocomial pathogen that has emerged as a cause of community-acquired pneumonia (CAP) in tropical regions. Few global epidemiological studies of CAP-Ab have been published to date, and no data are available on this disease in France. We conducted a retrospective chart review of severe cases of CAP-Ab admitted to intensive care units in Réunion University Hospital between October 2014 and October 2022. Eight severe CAP-Ab cases were reviewed. Median patient age was 56.5 years. Sex ratio (male-to-female) was 3:1. Six cases (75.0%) occurred during the rainy season. Chronic alcohol use and smoking were found in 75.0% and 87.5% of cases, respectively. All patients presented in septic shock and with severe acute respiratory distress syndrome. Seven patients (87.5%) presented in cardiogenic shock, and renal replacement therapy was required for six patients (75.0%). Five cases (62.5%) presented with bacteremic pneumonia. The mortality rate was 62.5%. The median time from hospital admission to death was 3 days. All patients received inappropriate initial antibiotic therapy. Acinetobacter baumannii isolates were all susceptible to ceftazidime, cefepime, piperacillin-tazobactam, ciprofloxacin, gentamicin, and imipenem. Six isolates (75%) were also susceptible to ticarcillin, piperacillin, and cotrimoxazole. Severe CAP-Ab has a fulminant course and high mortality. A typical case is a middle-aged man with smoking and chronic alcohol use living in a tropical region and developing severe CAP during the rainy season. This clinical presentation should prompt administration of antibiotic therapy targeting Ab.

Case #3: In December 2017, a 59-year-old woman with a body mass index (BMI) of 14 kg/m 2 was admitted to the emergency department of a peripheral hospital in Reunion Island for alcohol withdrawal delirium with seizures.The patient had a history of chronic alcohol use, high blood pressure, and smoking (40 pack-year).She was unemployed.She presented with confusion and tachycardia (130 bpm).Blood alcohol level was 0.55 g/L.Diazepam and vitamin therapies were initiated.On the night of day 1, the patient developed acute respiratory failure associated with right chest pain and hypotension.She received a high concentration oxygen mask and 2 liters of isotonic fluid.A chest CT scan showed right lower lobe pneumonia.After her circulatory and respiratory status deteriorated, the patient was intubated and received noradrenaline up to 5 mg/h.She was started on ceftriaxone and spiramycin and transferred to the ICU of Saint-Denis University Hospital.She presented with septic shock and oliguria on admission to ICU.Laboratory tests showed neutropenia (absolute neutrophil count 0.22 G/L), lymphopenia (lymphocyte count 0.25 G/L), thrombocytopenia (platelet count 78 G/L), and elevated AST levels (205 UI/L).Arterial blood gas analysis found metabolic acidosis (pH 6.99) with hyperlactatemia (lactate levels 5.2 mmol/L).Gram staining of the tracheobronchial aspirate revealed numerous Gram-negative bacilli and Gram-positive cocci with some yeasts.On day 2, the patient was started on piperacillin-tazobactam and gentamicin.Renal replacement therapy was initiated, and bicarbonate fluids were used.The evolution was rapidly unfavorable.The patient progressed to refractory shock despite receiving noradrenaline (up to 15 µg/kg/min), dobutamine (up to 5 µg/kg/min), and fluids (ringer's lactate and albumin solution).The use of protective ventilation and cisatracurium in front of severe ARDS, did not prevent the worsening of hypoxemia.Death occurred on day 3.The tracheobronchial aspirate was positive for A. baumannii postmortem (Appendix 3).

Case #4:
In April 2018, a 51-year-old man was admitted to the emergency department of Saint-Pierre University Hospital for fever and dyspnea that had been ongoing two days.The patient had a history of smoking (20 pack-year), chronic alcohol use, and cirrhosis (Child B) due to chronic hepatitis C. In 2010, he had developed a pulmonary abscess caused by Escherichia coli and complicated by pleural empyema.He worked as a trader.On admission, he presented with dyspnea requiring oxygen therapy (4 L/min).Laboratory tests showed acute renal failure (creatinine levels 219 µmol/L); elevated AST levels (80 UI/L), and leukopenia (absolute leukocyte count 3 G/L).Arterial blood gas analysis found hypoxemia (Pa02 60 mmHg) and hyperlactatemia (lactate levels 2.6 mmol/L).A chest radiograph showed infiltration of the left lung (Appendix 4b).The patient was started on cefotaxime and spiramycin and then transferred to ICU.The clinical examination found a respiratory rate of 30 breaths/minute with signs of struggle and coarse inspiratory crackles in the left lung.On day 2, the patient was intubated for respiratory failure du to ARDS and switched to piperacillin-tazobactam.
Respiratory and blood samples collected on admission were positive for A. baumannii (Appendix 4a).Antibiotic therapy was changed to piperacillin alone for 10 days.The patient received RRT until renal recovery (weaning on day 12).He was extubated on day 8. Colitis due to Clostridium difficile was diagnosed and treated with metronidazole.The patient was transferred to the nephrology department on day 14 and was discharged from hospital on day 20.

Case #5:
In January 2019, a 66-year-old man was admitted to the emergency department of a peripheral hospital in Reunion Island with productive cough and fever that had been ongoing for 3 days.The patient had a history of smoking, chronic alcohol use, and acute alcoholic hepatitis.The patient had developed ENT neoplasia in 2014.He was a retired mechanic.On admission, he presented with fever, tachycardia, and dyspnea.A chest radiograph showed right lower lobe pneumonia.Antibiotic therapy with amoxicillin-clavulanic acid was initiated.The patient received 1.5 liters of crystalloid fluids for hypotension and a high concentration oxygen mask followed by noninvasive ventilation.On the night of day 1, he received invasive mechanical ventilation and noradrenaline and was transferred to the ICU of Saint-Denis University Hospital.Laboratory results showed leukopenia (absolute leukocyte count 0.6 G/L), thrombocytopenia (platelet count 88.0 G/L), acute renal failure (creatinine levels 98.0 µmol/L; blood urea nitrogen levels 10.3 mmol/L), elevated AST levels (215 UI/L), respiratory acidosis (pH 7.17; pCO2 50 mmHg), and hyperlactatemia (lactate levels 6.3 mmol/L).The patient presented with septic shock and tachycardia due to persistent atrial fibrillation.A chest radiograph showed a white right lung and a chest CT scan revealed lower lobe pneumonia, with predominance of the right lobe (Appendix 5b).Gram-positive bacilli and Grampositive cocci were detected on bronchoalveolar lavage.On day 2, the patient was switched to cefotaxime, spiramycin, metronidazole, and amikacin.He presented with cardiac arrest (no-flow 0 min; low-flow 3 min) and was resuscitated with adrenalin (1 mg).Over the next 12 hours, he received noradrenaline (3 µg/kg/min), dobutamine (15 µg/kg/min), as well as crystalloid and colloid fluids.Antibiotic therapy was changed to piperacillin-tazobactam. Metabolic acidosis with hyperlactatemia (lactate levels 10 mmol/L) persisted despite the initiation of RRT.The deteriorating respiratory status required recommended treatment for severe ARDS (protective ventilation, neuromuscular blocking agents, and prone positioning therapy).Respiratory samples were positive for A. baumannii (Appendix 5a).Death occurred on day 3 due to multiple organ failure.
Case #6: In March 2020, a 55-year-old man with a BMI of 19 kg/m 2 was admitted to the emergency department of a peripheral hospital in Reunion Island after 1 month of cachexia and 1 week of productive cough.The patient had a history of chronic alcohol use and smoking (40 pack-year).He was a retired policeman.Clinical examination showed dyspnea, tachycardia, and hypotension.A chest CT scan revealed left lower lobe pneumonia and diffuse emphysema.Laboratory results showed leukopenia (absolute leukocyte count 0.5 G/L), elevated AST levels (136 UI/L), and venous hyperlactatemia (11 mmol/L).High flow nasal cannula oxygen therapy (60 L/min, FiO2 60%) and fluid therapy were initiated.The patient was started on ceftriaxone and spiramycin.Arterial blood gas analysis found hypoxemia (Pa02 84 mmHg) and hyperlactatemia (lactate levels 6.3 mmol/L).The patient was transferred to the ICU of Saint-Denis University Hospital for suspected SARS-CoV2 infection, where he was intubated and mechanically ventilated.He rapidly developed severe ARDS.Amikacin and cefotaxime were added to the antibiotic regimen.The patient developed left ventricular dysfunction (LVEF<15%), which required higher doses of catecholamines and the addition of dobutamine.Renal replacement therapy was initiated.Gram staining revealed numerous Gramnegative bacilli.Antibiotic therapy was changed to piperacillin-tazobactam and amikacin.No evidence of SARS-CoV2 infection was found.The patient rapidly progressed to multiple organ failure despite optimal management.Death occurred on day 2. The tracheobronchial aspirate was positive for A. baumannii postmortem (Appendix 6).

Case #7:
In May 2022, a 58-year-old man called emergency services for dyspnea and chest pain.The patient had fallen from a height the previous day, following approximately 3 weeks of productive cough and cachexia.He had a history of chronic alcohol use and smoking (50 pack-year).He work as farmer.On admission to the emergency department of Saint-Denis University Hospital, he presented with fever, respiratory failure, and hypotension requiring fluid therapy.A chest radiograph showed left lung infiltration.Antibiotic therapy with ceftriaxone and spiramycin was initiated.Dyspnea and hypoxemia persisted despite the use of a high concentration oxygen mask.The patient was transferred to ICU, where he was rapidly intubated.Laboratory results showed thrombocytopenia (platelet count 118 G/L) and elevated D-dimer levels (15,142 µg/L).The patient received the recommended treatment for severe ARDS.He then presented with septic shock, which prompted the administration of catecholamines up to 10 µg/kg/min.Direct exam showed some Gram-positive bacilli and numerous Gram-negative bacilli on pulmonary sample; and Gram-negative bacilli on blood sample.Multi-drug sensitive A. baumannii was detected in blood and respiratory samples (Appendix 7).After 24 hours of inappropriate antibiotic therapy, the patient was switched to ceftazidime (7 days) and amikacin (2 days).On day 2, he presented with cardiogenic shock likely due to septic myocarditis, which prompted the administration of dobutamine.On day 4, catecholamines were stopped and diuretic therapy was initiated (for 4 days).On day 7, the patient was successfully weaned from mechanical ventilation.The fever stopped and the disseminated intravascular coagulation observed on admission to ICU began to regress.The patient was discharged from ICU on day 10.

Case #8:
In October 2022, a 59-year-old man called emergency services after 3 days of cachexia and 1 day of dyspnea and chest pain.He had a history of chronic alcohol use, smoking, and limping after a