Community‐acquired necrotizing pneumonia caused by methicillin‐resistant Staphylococcus aureus in a healthy pregnant woman after being infected with influenza A: A case report for early warning

Abstract

A previously healthy woman, 5 weeks pregnant, was admitted to the intensive care unit in critical condition for septic shock and acute respiratory distress syndrome due to methicillin‐resistant Staphylococcus aureus (MRSA) after being infected with Influenza for 3 days. The patient in this case suffered from severe sequelae due to necrotizing pneumonia and later died on the 20th day after admission. We would like to remind clinicians to be aware of this rare but serious diagnosis. The key is to begin appropriate treatment immediately because MRSA necrotizing pneumonia is mediated by toxins and once the toxins are released they cannot be limited by antibiotic treatments. Necrotizing pneumonia related to MRSA should be considered in young patients with pneumonia, sepsis, and neutropenia following seasonal influenza infection with rapidly progressive symptoms.

We present a fatal case of ARDS due to MRSA in a healthy pregnant woman post influenza A infection. The patient in this case suffered severe sequelae after a bout of necrotizing pneumonia, pneumothorax, bronchopulmonary fistula, and long‐term mechanical ventilation. In light of this case, we would like to warn clinicians to be aware of this rare but serious diagnosis.

INTRODUCTION

Staphylococcus aureus can cause rapidly progressive necrotizing pneumonia, even in young and previously healthy people. Pneumonia caused by S. aureus often occurs after influenza infection. We present the case of a 40‐year‐old female patient with a healthy history, 5 weeks pregnant, who was diagnosed with methicillin‐resistant S. aureus necrotizing pneumonia (MRSA) after being infected with influenza A. The patient was hospitalized in a state of septic shock and acute respiratory failure with blood culture results on admission positive for methicillin‐resistant S. aureus (MRSA). Despite treatment with vancomycin (MIC <1 μg) and monitoring of antibiotic dosage according to blood levels, necrotizing pneumonia still progressed along with acute respiratory distress syndrome (ARDS).

CASE REPORT

A 40‐year‐old woman with no previous comorbidities, 5 weeks pregnant, presented with fever, dry cough, and sore throat 3 days before admission. She entered the intensive care unit with a body temperature of 37°C, blood pressure of 80/50 mm Hg, heart rate of 140 beats/min, and oxygen saturation of 98% while on a 10‐litre oxygen mask/min. Blood gas test results showed PaO₂: 59 mmHg, PaCO₂: 32 mmHg, pH: 7.45, and lactate: 2.4 mmol/L. Blood tests showed a haemoglobin level of 150 g/L, leukocyte level of 3.5 × 10⁹/L, thrombocyte level of 185 × 10⁹/L, creatinine level of 58 μmol/L, and CRP level of 16.3 mg/L, Procalcitonin level of 25.1 mg/dL (Table 1). Chest x‐ray image at the time of admission to the intensive care unit showed consolidation signs in the right lower lobe of the lung. The patient was diagnosed with sepsis, received intravenous fluids, blood and sputum cultures, and meropenem 3 g/day (Table 2), vasopressor support.

TABLE 1.

Blood samples.

	Leukocyte	Red blood cell	Neutro	Haemoglobin (g/L)	Thrombocyte	Ure (mmol/L)	Creatinin (μmol/L)	CRP (mg/L)	PCT (mg/dL)	Serum vancomycin concentration
Day 1	3.5× 109	4.99 × 1012	76.9%	150	185 × 109	3.62	58	16.3	25.1	21.38
Day 2	1.48 × 109	4.36 × 1012	70.1%	133	82 × 109			224.8		16.74
Day 3	3.9 × 109	3.8 × 1012	89%	117	58 × 109	1.8	39	280	187	33.44
Day 4	5.74 × 109	3.95 × 1012	88.5%	118	62 × 109	3.45	25	203	94.6	22.7
Day 5	14 × 109	3.99 × 1012	90%	120	103 × 109	4.3	29	142	50	24.62
Day 10	17 × 109	2.85 × 1012	88%	86	237 × 109	2.8	30	158	4.67	27.48
Day 13	15.87 × 109	3.33 × 1012	86.7%	97	403 × 109	2.22	26	191.3	3.43	22.96
Day 14	17.13 × 109	3.3 × 1012	90%	99	497 × 109	5.4	44	167.1	1.9	30.6
Day 19	14 × 109	3.06 × 1012	89.3%	88	105 × 109	10.51	35	82.8		31.61
Day 20	16.67 × 109	3.2 × 1012	90.5%	92	120 × 109	10.9	45	44.2

TABLE 2.

Antibiotic therapy using during intensive care unit.

	Meropenem	Vancomycin	Ceftaroline	Tigecycline	Linezolid
Day 1	1 g × 3	Serum concentration
Day 2	1 g × 3	Serum concentration
Day 3		Serum concentration
Day 4		Serum concentration
Day 5		Serum concentration
Day 6		Serum concentration	600 mg × 2
Day 7		Serum concentration	600 mg × 2
Day 8		Serum concentration	600 mg × 2
Day 9		Serum concentration	600 mg × 2
Day 10		Serum concentration	600 mg × 2
Day 11		Serum concentration	600 mg × 2	100 mg × 2
Day 12		Serum concentration	600 mg × 2	100 mg × 2
Day 13		Serum concentration	600 mg × 2	100 mg × 2
Day 14		Serum concentration		100 mg × 2
Day 15		Serum concentration		100 mg × 2
Day 16		Serum concentration		100 mg × 2
Day 17		Serum concentration		100 mg × 2
Day 18		Serum concentration			600 mg × 2
Day 19		Serum concentration			600 mg × 2
Day 20		Serum concentration			600 mg × 2

Microbiological tests collected on admission showed that S. aureus in blood and sputum cultures was sensitive to vancomycin (MIC <1 μg/mL). Leukocyte levels the second day after admitting to the intensive care unit decreased to 1.48 × 10⁹/L, Serum Procalcitonin increased to 224.8 mg/dL (Table 1), sputum polymerase chain reaction (PCR) testing was positive for influenza A. She was then treated with continuous intravenous vancomycin, adjusting the antibiotic dose according to blood levels. However, the respiratory failure did not improve, and the patient was intubated and mechanically ventilated on the 3rd day after admission to the intensive care unit. On day 5, chest computed tomography (CT) showed dilatation and consolidation in the left lung, although the serum concentrations of vancomycin were maintained at approximately 20–25 μg/mL. The patient's clinical condition worsened; she had continuous high fever, and blood and sputum culture results were still positive with S. aureus. A chest CT on day 10 showed worsening consolidation, multiple cavities in the left lung, and consolidation in the right lung (Figure 1). The patient then was treated with a combination of the antibiotic continuous infusion vancomycin and high‐dose tigecycline (Table 2). On day 18, she still had a high fever. A chest CT showed an increased right pulmonary cavity and right pneumothorax, and the patient was inserted a tube to drain the right pleural cavity (Figure 2). The patient was then given linezolid combined with continuous intravenous infusion of vancomycin (Table 2). After that, inflammatory markers improved, with a decrease in white blood cells and CRP, and the patient had no fever. However, the bronchopulmonary fistula continued, and the patient died on day 20 after admission.

FIGURE 1.

Computed tomography scan of the chest on day 10 showed massive bilateral consolidation with air bronchogram and multiple cavities in the right lung indicating extensive parenchymal destruction.

FIGURE 2.

Computed tomography scan of the chest on day 18 showed an increased right pulmonary cavity, right pneumothorax, drain tube in the right pleural cavity. Consolidation with several small cavities in the left lung.

DISCUSSION

Community‐acquired necrotizing pneumonia due to S. aureus is an infection with a high mortality rate, often encountered in young and healthy patients after seasonal influenza infection. The main features are a flu‐like prodrome, leukopenia, rapid progression leading to septic shock, respiratory failure due to multilobe pneumonia, accompanied by multilobular necrosis, purulent cough, and lung cavitation. ¹

In systematic analysis, an influenza‐like prodrome predicts a fatal outcome. It is difficult to give an accurate estimate of the true prevalence of influenza infection because influenza testing is not routinely performed, and the sensitivity of rapid testing ranges between 50% and 70%. ² Influenza interferes with the process of finding and attacking phagocytic cells and damages the tracheal‐bronchial epithelium, resulting in impaired excretory clearance and creating conditions for resident bacteria to grow and cause disease. ³ , ⁴ , ⁵ Flu‐like symptoms can also be caused by other respiratory viruses or by S. aureus itself. Approximately 20%–30% of healthy individuals are regularly colonized with S. aureus. ⁵ , ⁶ Once hospitalized, these carriers are at higher risk of severe S. aureus infection caused by their colonizing strain.

The optimal treatment for S. aureus community acquired pneumonia (CAP), especially MRSA CAP, has not yet been determined. The Infectious Diseases Society of America/American Thoracic Society CAP guidelines published in 2016 for adults recommend vancomycin or linezolid for CAP‐MRSA, although the most effective therapy has not been established. ⁷ Vancomycin has been established as the mainstay therapy for MRSA infections; however, clinical failures have also been reported with increasing minimum inhibitory concentrations for vancomycin in vitro. ⁸ , ⁹ Even when S. aureus remains susceptible to vancomycin, low drug concentrations in target tissues result from widespread tissue necrosis, leading to poor antibiotic diffusion and increased volume of distribution associated with sepsis. Patients may not respond adequately to vancomycin, while the addition of antibiotics that inhibit toxin production such as clindamycin and linezolid may give patients more opportunities.

In conclusion, the patient in this case suffered severe sequelae after a bout of necrotizing pneumonia, pneumothorax, bronchopulmonary fistula, and long‐term mechanical ventilation. In light of this case, we would like to warn clinicians to be aware of this rare but serious diagnosis. The most important thing is to start proper treatment immediately because MRSA necrotizing pneumonia is mediated by toxins, and once the toxins are released, they cannot be limited by therapeutic methods with antibiotics. ¹⁰ MRSA necrotizing pneumonia should be considered in young patients with pneumonia, sepsis, and neutropenia following seasonal influenza infection with rapidly progressive symptoms.

AUTHOR CONTRIBUTIONS

Conceptualization: Duong Le Xuan, Duc Vu Anh, Hoa Do Thanh, Ghi Nguyen Hai. Data curation: Duong Le Xuan, Hoa Do Thanh. Formal analysis: Duong Le Xuan, Hoa Do Thanh. Supervision: Duong Le Xuan. Writing – original draft: Duc Vu Anh, Ghi Nguyen Hai. Writing – review & editing: Duong Le Xuan, Hoa Do Thanh, Ghi Nguyen Hai. Read and approve the final version of manuscript: all authors. All authors listed have significantly contributed to the investigation, development, and writing of this article.

CONFLICT OF INTEREST STATEMENT

None declared.

ETHICS STATEMENT

Written informed consent was obtained from the patient's relatives for publication of this case report. The study was approved by 108 Military Center Hospital ethics committee in biomedical research.

Do Thanh H, Anh DV, Hai GN, Le Xuan D. Community‐acquired necrotizing pneumonia caused by methicillin‐resistant Staphylococcus aureus in a healthy pregnant woman after being infected with influenza A: A case report for early warning. Respirology Case Reports. 2024;12(7):e01396. 10.1002/rcr2.1396

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.