Primary lung abscess due to multidrug-resistant Klebsiella pneumoniae

Abstract

Primary lung abscess as a complication of necrotising community-acquired pneumonia due to multidrug-resistant (MDR) Klebsiella pneumoniae is rare. A 63-year-old man with a medical history of type 2 diabetes mellitus and chronic kidney disease was diagnosed with lung abscess due to MDR Klebsiella pneumoniae, a rare organism as a causative agent for community-acquired pneumonia. This unusual case revealed therapeutic challenges faced owing to factors such as drug-resistant pathogen, longer duration of antibiotics required for lung abscess and the chronic kidney status of the patient limiting the dosage of antibiotics. The clinical nuggets discussed in this case might pave the way in the future for management guidelines to be formulated in optimising the selection and duration of therapy for lung abscesses with MDR aetiology and in early recognition of this rare but dreaded entity.

Background

Lung abscess is often a commonly encountered respiratory condition. However, in certain clinical contexts, it poses both diagnostic dilemmas and management challenges.

Often a community-acquired pneumonia can develop complications such as necrotisation forming a lung abscess. This is encountered in patients with depleted systemic immunity such as with diabetes, chronic kidney disease and those on immunosuppressant therapy. It could also result from suboptimal choice, dose and duration of antibiotics and in some cases multidrug-resistant (MDR) infections. Our case serves as a prototype to highlight a combination of such factors leading to a lung abscess.

MDR infections are the new epidemic with an untold impact on mortality and morbidity. Rampant and unregulated use of higher antibiotics in community and hospital setting and antibiotic practices in dairy and poultry industry has led to a surge of deadly MDR pathogens. Emergence of MDR pathogens in a community setting as in our patient is a matter of grave concern, an entity that needs to be sensitised among the physicians for an early and an accurate diagnosis.^{1 2} Lung abscess necessitates appropriate sensitive antibiotics for prolonged duration for 4–6 weeks. Our case highlights the challenges faced due to the resistant nature of the infection, narrow selection, choice of antibiotics available and the dosage considerations in view of compromised chronic kidney status.

We report the case of a 63-year-old man with a primary lung abscess due to community-acquired pneumonia caused by MDR Klebsiella pneumoniae.

Case presentation

A 63-year-old man presented to the casualty with a 10-day history of fever and cough with expectoration that was yellow in colour and copious in amount.

Along with cough, he developed left-sided chest pain which was pleuritic in nature and experienced occasional breathlessness. He had a medical history of diabetes, chronic kidney disease and ischaemic heart disease with percutaneous transluminal coronary angioplasty done in 2016.

On admission, he was febrile, pulse 80 beats per minute, blood pressure 130/80 mm Hg and oxygen saturations 95% on room air. On examination, he had crepitations at the left lung base with decreased breath sounds and dullness to percussion at the left lung field.

Investigations

Blood investigations showed haemoglobin of 9.7 g/dL and white cell count of 19 800×10⁹/L of blood with neutrophilia. Chest X-ray showed air-fluid level in the left lower lung field (figure 1A). High-resolution CT scan of the chest suggested consolidation in the lingular segments of the left lung along with area of breakdown and abscess formation with air-fluid level (figure 1B). Bronchoscopy revealed copious secretion from the lingular segment with mucosal oedema and irregularity without an endoluminal lesion and was suggestive of a lingular abscess (figure 2). Bronchoscopic biopsy from area of mucosal irregularity ruled out tuberculosis and malignancy and showed evidence of chronic inflammatory and suppurative process consistent with clinical diagnosis of lung abscess. Bronchial lavage culture grew Klebsiella pneumoniae. Subsequently, the culture and sensitivity reports showed it to be MDR pathogen resistant to all parenteral cephalosporins, aminoglycosides, carbapenems, piperacillin plus tazobactam and quinolones with sensitivity only to ceftazidime–avibactam and fosfomycin.

Figure 1.

(A) Chest X-ray shows air-fluid level in the left lower lung field. (B) High-resolution CT scan of the chest suggests consolidation and ground-glass attenuation with areas of breakdown and abscess in the lingular segments of the left lung field.

Figure 2.

Bronchoscopy reveals copious secretion from the lingular segment with mucosal oedema and irregularity without an endoluminal lesion and was suggestive of a lingular abscess.

Culture tests were negative for melioidosis, fungal infection, acid fast bacilli and cartridge-based nucleic acid amplification test for tuberculosis. Xpert carba-R testing—carbapenem resistance molecular test—was carried out for bronchial lavage and confirmed presence of Klebsiella pneumoniae with detection of New Delhi metallo-beta lactamase and class D oxacillinase. The test was done as a cartridge-based real time PCR using Xpert Mycobacterium tuberculosis complex and resistance to rifampicin (MTB/RIF) ultra assay.

Utility of early bronchoscopy in cases of lung abscesses is reinforced with this case. Bronchoscopy rules out proximal obstructive lesions causing distal abscess. Bronchial aspirates for cultures provide a definitive early microbiological diagnosis which is essential to initiate specific antimicrobial therapy—a critical factor in outcome. In cases of MDR infections, Xpert carba-R testing is of immense value in identifying sensitivity and resistance spectrum to extended higher antibiotics.

Differential diagnosis

In cases of pneumonia not responding to treatment, patients should be re-evaluated for complications of pneumonia and causes for non-resolving pneumonia. These include lung malignancies causing proximal bronchial obstruction with distal pneumonia, necrotising pneumonia, MDR causes for pneumonia and granulomatous causes for pneumonia such as tuberculosis and mycotic infections.

Bronchoscopy with visualisation, biopsy and cultures ruled out tuberculosis, fungal infections and malignancy.

Treatment

The patient was initially started on empiric antibiotics with meropenem and clindamycin. After obtaining bronchial lavage cultures on day 5, the patient was started on specific antibiotics as per culture and sensitivity report.

The patient was then started on fosfomycin but unfortunately he developed an allergic reaction and it had to be discontinued. Antibiotic was escalated to ceftazidime plus avibactam with dose adjustment according to creatinine clearance. He received physiotherapy regimen for drainage of left lingular and lower lobe segments with active clearance techniques.

Outcome and follow-up

After a change in antibiotics to ceftazidime plus avibactam and its continuation for a week, the patient’s condition started to get better symptomatically. He became afebrile on day 3 of antibiotics, his total leucocyte counts reduced sequentially and his daily sputum expectorant reduced in quantity. He tolerated the treatment well and did not develop any complications during his stay in hospital. His renal parameters improved as well. He was continued on ceftazidime plus avibactam for 4 weeks. Chest X-ray repeated after 4 weeks and 6 weeks showed significant reduction in size of the abscess.

Discussion

Lung abscess is defined as pulmonary tissue necrosis and formation of necrotic debris or fluid-filled cavities caused by microbial infection. When such an abscess is less than 2 cm, it is referred to as necrotising pneumonia or lung gangrene. Not being able to detect a lung abscess early and treat it optimally is associated with poor clinical prognosis.³

Lung abscesses commonly follow a pre-existing infection and secondary lung abscesses are more common than the primary type. Aspiration of the contents in the oropharynx and pneumonia lead to primary lung abscess. Secondary lung abscesses occur due to spread of infection from an extrapulmonary site or following a respiratory pathology such as obstruction and bronchiectasis, frequently seen in an immunecompromised person. People with history of alcohol abuse, poor oral hygiene, seizure disorders, neuromuscular disorders and stroke are at a higher risk of developing lung abscess.^{4 5}

Anaerobic infections are common to cause lung abscesses when compared with aerobes such as Klebsiella pneumoniae especially in immunecompromised states.⁶

Men are at a higher risk of suffering from lung abscess than women.⁷ People with increased age, malnutrition, poor immunity and malignancy are more susceptible. Mortality rate of patients who developed lung abscess was as high as 75% if they are in a poor immune state.⁸ Diabetes continues to persist as a potential risk factor, especially with Klebsiella pneumonia. A study showed that most people with underlying comorbidities, especially diabetes, predisposes to a MDR Klebsiella pneumonia.⁹ There are not much data about the incidence of MDR Klebsiella in people with comorbidities such as chronic kidney disease.

One of the most common and emerging threats to public health in present decade is MDR microbes. Initially associated with nosocomial infections, these pathogens are now increasingly a part of community-acquired infections. The spread of MDR microbes is associated with greater probability of mortality, antibiotic usage and healthcare costs.¹⁰ Large virulence plasmid, increased capsule and aerobactin production are the genetic factors responsible for this trend. Antibiotic resistance is caused by the expression of extended-spectrum beta-lactamases and recently carbapenemases, making the bacteria resistant to the most common beta-lactams. Genetic variation was found more in beta-lactams resistance determinants. The different resistance mechanisms suggest the selection and multiplication of MDR bacteria, which is difficult to control with limited therapeutic options. The astounding transmissibility incorporated with finite remedial choices to fight MDR isolates substantially reduces the effectual dominion over these microbes in the nosocomial setting.¹¹ Patients infected with MDR bacteria are at a higher risk of worsening of disease when compared with patients infected with vulnerable microbes.^{12 13}

Lung abscesses following Klebsiella pneumoniae develop weeks after the infection as a complication. It usually follows a hospital-acquired pneumonia and acts as a superinfection when the patient is receiving ongoing treatment with resistant antibiotics for an underlying pneumonia. Due to spread of epidemic resistance plasmids and high-risk clones, Klebsiella pneumoniae has become a MDR pathogen causing outbreaks in hospitals recently. With antibacterial resistance on a rising trend, all facets of modern medicine have been threatened including care in oncology and surgery.¹⁴ Adding to this is the cost of treatment of such infections and the association of regular use of broad-spectrum antibiotics.¹⁵ This in turn increases the rates of MDR bacteria thus creating a dilemma for the healthcare system. Generally, metastatic infections are caused by MDR Klebsiella pneumoniae. As already known, lung abscesses frequently occur due to these metastatic infections from a primary infectious origin. A primary lung abscess due to this strain is very rare.

Taiwan and Japan have documented a few reports of MDR Klebsiella pneumoniae causing primary lung abscesses over the recent years.¹⁶

In 2005, Wang et al did a study in Taiwan to review on the changing pathogenicity of primary lung abscess comparing Klebsiella pneumoniae and anaerobes. The study revealed that the possible aetiological agent should be considered as Klebsiella pneumoniae in causing community-acquired lung abscess in adults. Diabetes is taken as an important risk factor. Most adults were resistant to penicillin and clindamycin. Beta-lactamase inhibitor or third-generation cephalosporin plus clindamycin or metronidazole is the preferred therapy as per the guidelines for 4–8 weeks. A combination therapy is far better than monotherapy. We adapted to the guidelines and started the patient on empiric antibiotics which was later streamlined to specific antimicrobials based on culture sensitivity pattern. However, there exists a paucity of data on treatment of lung abscess due to MDR aetiology. There is little consensus presently on the duration of antibiotics to be administered in patients with dose adjusted regimen and with higher new antibiotics such as polymyxin and ceftazidime plus avibactam.

Patient’s perspective.

We (the patient’s kin) were of the belief that the patient was suffering from a respiratory condition and could have developed pneumonia. After having been advised and counselled by the treating physician, we were aware that he developed a complication of pneumonia which was called lung abscess.

Learning points.

• Community-acquired multidrug-resistant (MDR) infections such as Klebsiella though rare are an emerging problem especially in diabetics and chronic kidney disease states.

• Lung abscess primarily caused by anaerobes can rarely be a complication of necrotising MDR Klebsiella.

• Bronchoscopy aided by conventional cultures and molecular bases techniques provide for an accurate and early diagnosis, a key outcome factor in lung abscess.

• Precise treatment options in the setting of MDR organisms need to be explored.

Ethics statements

Patient consent for publication

Obtained.