Rapid spread and high mortality due to community-acquired pneumonia caused by Acinetobacter baumannii (CAP-AB) in a Covid-19 intensive care unit

ABSTRACT

Acinetobacter baumannii is a rare but dangerous gram-negative bacteria causing nosocomial infections, especially in intensive care units. The increased use of antibiotics in the treatment of bacterial infections leads to drug resistance, delays, or failures in treatment. The patient is a 48-year-old man with coronavirus disease (COVID-19) being treated in the intensive care unit. After contracting Acinetobacter baumannii, the patient’s condition deteriorated, and he developed severe pulmonary problems. Due to the unknown presence of Acinetobacter baumannii in the patient, this bacterium transmitted to six other patients in the ward, which resulted in their deaths. In this report, we describe the causes and risk factors of the disease, and the results of laboratory tests and therapeutic processes.

Introduction

Acinetobacter baumannii is a nosocomial infection highly resistant to broad-spectrum antibiotics and a recurring problem for immunosuppressed patients. Acinetobacter baumannii also can be catastrophic for COVID-19 patients admitted to intensive care units, whose main treatment is immunosuppressive drugs. The need to pay attention to patient isolation and culturing prior to admission to the intensive care unit is urgent. Nosocomial infections are a problem for the medical community, causing substantial human cost and financial losses annually.[1] Acinetobacter species, including baumannii, are the most common cause of nosocomial infections. Most infections caused by this microorganism occur in the hospital, and risk factors include long-term antibiotic use, long intensive care unit stays, and serious underlying diseases.[2] A nosocomial infection, Acinetobacter pneumonia, mainly affects patients in intensive care units requiring mechanical ventilation.[3] In addition to the above, patients with immunodeficiency or underlying diseases such as chronic obstructive pulmonary disease or diabetes are at risk for Acinetobacter infection.[2] Over the past 25 years, however, there have been cases of community-acquired pneumonia caused by Acinetobacter baumannii reported in people who have not had any healthcare experience or hospitalization history.[4] These are found primarily in northern Australia and Asia, Thailand, China, and Taiwan. Acinetobacter also is found in soil, livestock, and other animals that act as reservoirs of community-acquired Acinetobacter.[5] Although community-acquired Acinetobacter baumannii infection is less resistant than nosocomial infections, studies show an increase in mortality from community-acquired Acinetobacter baumannii.[6]

Case presentation

The patient was a 48-year-old man admitted to the emergency department due to shortness of breath and cough. After a lung CT scan with severe pulmonary involvement and ground glass opacity (GGO), he was admitted to the ward. The patient was treated with Remdesivir (200 mg IVinf in day one and 100 mg IVinf from the second day for 5 days) and intravenous pulse steroid therapy (methylprednisolone 1 g IV daily for three days followed by 60 mg IV twice daily). Due to hypoxia the fifth day after admission, we started noninvasive ventilation (NIV) and requested IL-6 and TNF-a serum levels. The patient also developed elevated level of cytokines (IL-6 = 105 pg/ml, TNF-a = 5.6 pg/ml), and after testing for tuberculosis and Procalcitonin, Tocilizumab was started with 2 doses of 400 mg Tocilizumab IV injected 12 h apart.

After 48 h, following patient improvement and increase in oxygen saturation, NIV was discontinued. Oxygen therapy continued OMR (oxygen mask with reservoir bag). After a few days, the patient was discharged from the intensive care unit to a medical ward. However, due to a sudden drop in oxygen saturation, the patient was connected to BIPAP machine through a face mask (ST I = 20 E = 8 RR = 16). Within 24 h, he was intubated and connected to ventilator. Over several days, the patient’s endotracheal tube secretion was positive for multidrug resistance (MDR) Acinetobacter baumannii. He was isolated and antibiotic treatment started with high-dose Colistin (9 million IU per day), Meropenem (6 grams per day), and Ampicillin/Sulbactam (12 grams per day).

Fortunately, the patient responded to treatment 14 days after intubation and extubated after 26 days of hospitalization. After the patient’s positive culture result for MDR Acinetobacter baumannii, the six other patients in the intensive care unit also were sampled and all endotracheal tube secretion results were positive for MDR Acinetobacter baumannii. Colistin and Ampicillin/Sulbactam were started for all six patients, but they did not respond and died.

Discussion

Among immunosuppressed patients in the intensive care unit, those with COVID-19 required to use corticosteroids and suppress the immune system to prevent complications and severity of the disease are more likely to develop Acinetobacter infections.[7] The distribution of pathogenic microorganisms varies in different studies. In one study, Meric et al.,[8] (2005) reported the Acinetobacter species (with 26.8%) as the second most common organism in the ICU. In a study by Sileem et al.,[9] (2007), they reported a 9.2% prevalence of Bumani bacterium infection, which was resistant to most antibiotics.

Strong resistance of this bacterium to most drugs requires more preventive measures. The CDC provides recommendations on prevention of multidrug-resistant organisms (MDRO) transmission in intensive care units including hand hygiene as a core element during patient contact, active and regular monitoring, training of healthcare staff, and thorough cleaning of hospital environments and equipment contaminated with these organisms.[10] Many organisms also may be transmitted through food to humans in the hospital environment, where they develop antibiotic resistance and cause disease in hospitalized immunocompromised individuals.[11]

Due to indiscriminate use of antibiotics and rapid growth of antibiotic resistance, especially in developing countries, the need is to identify and evaluate the resistance pattern of pathogenic organisms, especially species associated with hospital-acquired infections. Acinetobacter baumannii is a serious and dangerous problem in the ICU. Given its association with COVID-19 infection and use of immunosuppressive drugs, the issue is increasingly significant. With the relatively easy and rapid transmission of this infection and high mortality rate, early diagnosis and early treatment of this organism are important. With its high resistance to environmental conditions and presence in hospital settings, it is necessary to consider the hospital environment, especially the ICU, as the main source of this bacterium. Therefore, disinfection of the internal environment of the ward, tools, and equipment should be considered.

Due to the high transmission capacity through suction devices, oxygen generator, and other hospital equipment, patients should be isolated in the COVID-19 ward as soon as possible. Endotracheal secretion culture for detecting Acinetobacter and evaluating antibiotic resistance in COVID-19 intensive care units and early detection of nosocomial infections due to high prevalence is useful in reducing patient mortality. Also, with cases of Acinetobacter baumannii reported from the community, it is recommended that isolation measures be implemented in COVID-19 intensive care units. This is due to immunosuppression of patients with immunosuppressive drugs, measures such as plasmapheresis, and dialysis with an anti-complement filter that suppresses the immune system.

In our ward, all isolation and culture measures were performed before ICU admission. However, due to the one patient’s involvement with community-acquired Acinetobacter baumannii transferred from the emergency department to the ICU, we lost six other patients. So, we recommend obtaining cultures for all patients before admission to the COVID-19 control ward. If the Acinetobacter culture is positive, isolate the patient immediately to prevent transmission of the infection to other patients.

Ethical considerations

The study protocol was in compliance with the Declaration of Helsinki (1989 revision) and the participants had given consent to publish the clinical results of the study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.