Association between non-typhoidal Salmonella urinary tract infection and Klebsiella pneumoniae lung empyema

Abstract

Non-typhoidal Salmonella is a known but rare cause of urinary tract infections (UTI). It has been associated with the elderly, urological abnormalities and immunocompromised states. Klebsiella pneumoniae is a common cause of lung empyema, and is typically associated with diabetes and malignancy. Here, we report a patient who was found to have a Salmonella enteritidis bacteriuria as well as a lung empyema secondary to K. pneumoniae.

Introduction

Non-typhoidal Salmonella (NTS) is a known but rare cause of urinary tract infections (UTI). ¹ It has been associated with the elderly, urological abnormalities ² and immunocompromised states. ³ Klebsiella pneumoniae is a common cause of lung empyema ⁴ and is typically associated with diabetes and malignancy. ⁵ Here, we report a patient who was found to have a Salmonella enteritidis bacteriuria as well as a lung empyema secondary to K. pneumoniae.

Case report

This 64-year-old Chinese male presented to our local hospital with a two-day history of urinary frequency associated with daily tactile fevers for the past three weeks. He also reported having a productive cough with white phlegm for a month. His past medical history included paranoid schizophrenia, chronic obstructive pulmonary disease (COPD) with chronic type 2 respiratory failure, liver cirrhosis and primary hyperparathyroidism. Four months prior, he had been admitted to medical high dependency for his COPD exacerbation (his first exacerbation requiring admission). He uses a Spiolto Respimat inhaler regularly (a combination of tiotropium and oladaterol).

On admission, his temperature was 37°C. He remained afebrile throughout his admission. Microscopic examination showed white cells of >2250 WBCs/hpf and red cells of 2070 WBCs/hpf. His procalcitonin was elevated at 0.56. His C-reactive protein was 34.9mg/L. His full blood count demonstrated leucocytosis (white cells of 26) with neutrophilia. His renal panel and liver function tests were normal. A human immunodeficiency virus (HIV) screen, hepatitis B and hepatitis C screen were negative.

A chest x-ray on admission showed generalized emphysema with collapse-consolidation in the left lower zone from a left pleural effusion with an associated air-fluid level in the left apex, suggestive of a hydropneumothorax (Figure 1). A computed tomography (CT) scan of the chest demonstrated two large loculated collections in the left pleural space. An enlarged lower-left paratracheal lymph node was seen, but no other lymphadenopathy or primary lung masses were noted (Figure 2).

Figure 1.

Chest x-ray showing left hydropneumothorax.

Figure 2.

Computed tomography scan of the chest, showing two left loculated collections.

The patient was commenced on intravenous (i.v.) co-amoxiclav. Urine cultures collected prior to antibiotic treatment demonstrated S. enteritidis sensitive to ampicillin, ceftriaxone, ciprofloxacin and cotrimoxazole. The same organism was demonstrated on a gastrointestinal screen for pathogenic organisms but not grown in stool cultures. With suspicion of an empyema, a chest drain was inserted which drained large amounts of pus. Pleural fluid cultures from this eventually grew K. pneumoniae. Blood cultures taken on admission were negative. (This was, however, only done after i.v. co-amoxiclav had been started.)

As a previous case report had demonstrated NTS UTI in association with hyperparathyroidism and nephrocalcinosis, ⁶ a CT pyelogram was performed. This did not demonstrate any structural or filling defects with the urinary system or any aortic aneurysms.

The patient received i.v. co-amoxiclav for two weeks. He was discharged well with an additional two-week course of antibiotics, and currently has ongoing respiratory appointments.

Discussion

NTS UTIs have previously been reported to account for 0.024% of all positive urine cultures. ⁷ S. enteritidis is the most common serotype causing UTIs. ⁸ Case reports of associations with polycystic renal disease, ⁹ diabetes ¹ and acquired immune deficiency syndrome ¹⁰ have previously been described. However, a review of relevant literature on PubMed did not show any previous association with a lung empyema. Some risk factors that predisposed our patient to both conditions include male sex, age and diabetes. ¹¹ The patient was also underweight at 46 kg (body mass index 16.3 kg/m²), which in general increases the risk of infections, ¹² including pneumonias. ¹³

Previous reports have demonstrated a higher occurrence of NTS UTI in immunosuppressed individuals. ⁸ We did a HIV test in our case which was found to be negative. NTS infections have been associated with mycotic aneurysms. ¹⁴ None of this was demonstrated on this patient’s CT scan of the chest, abdomen and pelvis.

Previously, an association between NTS UTI and primary hyperparathyroidism has been described. ⁶ In that case report, bilateral nephrocalcinosis was found which likely predisposed the infection. As our patient had a history of primary hyperparathyroidism, we were careful to rule out nephrocalcinosis with a CT pyelogram. While this study did not demonstrate any urological abnormalities, it did demonstrate an enlarged prostate, which previously has also been found to be associated with NTS UTI. ¹⁵

As the patient was admitted four months prior for a COPD exacerbation, a nosocomial source of his K. pneumoniae infection was considered. This was felt to be unlikely, as a chest x-rays during that admission did not demonstrate a consolidation or empyema, and the patient was well after treatment of his exacerbation.

In this patient, both the NTS and Klebsiella pathogen were found to be sensitive to co-amoxiclav. He was treated with a total of six weeks of co-amoxiclav. Both infections often require a prolonged duration of antibiotics to treat. ¹⁵ Ciprofloxacin has previously been suggested as first-line treatment of NTS infections, as this antibiotic accumulates intracellularly where Salmonella pathogens tend to grow. ¹⁵ However, a Singapore-based study ¹⁶ demonstrated a 35.3% resistance to quinolones among NTS isolates versus a 5.9% resistance to co-amoxiclav. Hence, the use of co-amoxiclav as first-line treatment of NTS infections may be preferred in a Singaporean population.

Conclusion

We report a patient with both NTS UTI and Klebsiella pneumoniae empyema. Such rare causes of a UTI would warrant further investigations to rule out urological abnormalities. An interrogation of the parathyroid gland should be done as well in order to assess for hyperparathyroidism.