An unusual case of hyperammonemia in a 83-year-old woman

Ringing bells: Morganella morganii fights for recognition

OBJECTIVES

The global increase in rare opportunistic microbial infections is alarming. The current review was undertaken to study the diversified disease spectrum, pathogenicity, and resistance patterns of Morganella morganii.

STUDY DESIGN

This study is a review of the diversified disease spectrum of M. morganii.

METHODS

The articles used in this review were all extracted from PubMed and Google Scholar, using the terms 'M. morganii', 'prevalence', 'virulence factors', 'infections', 'resistance pattern', and 'genomics'. This review includes original articles, reviews, and case reports focusing on M. morganii, hospital-based prevalence studies, and studies on resistance in M. morganii published between 1906 and April 2019. Articles published in English, French, Spanish, and Chinese were reviewed.

RESULTS

M. morganii has had a significant impact as a clinical pathogen and the pace of its occurrence and the increase in its resistance rates puts this bacterium on the path to becoming the next 'superbug'. These developments not only impact M. morganii, but as a result of gene and plasmid transfer evolution, other clinical pathogens have been able to acquire their diverse intrinsic and acquired virulence genes. Its vast host range raises concerns around its capacity to generate new infections through novel symbiotic relationships.

CONCLUSIONS

M. morganii opportunism is being increasingly reported across the globe. This bacterium is accumulating intrinsic and acquired multidrug resistance genes, resulting in increased morbidity and mortality rates for M. morganii infections and complicating its treatment. M. morganii should be recognized as a clinically significant pathogen, and clinicians should place this microorganism in the list of causative possibilities during patient care. It is important for both the infection control activities in hospitals and in public health sector.

Hyperammonemia associated with distal renal tubular acidosis or urinary tract infection: a systematic review

BACKGROUND

Hyperammonemia usually results from an inborn error of metabolism or from an advanced liver disease. Individual case reports suggest that both distal renal tubular acidosis and urinary tract infection may also result in hyperammonemia.

METHODS

A systematic review of the literature on hyperammonemia secondary to distal renal tubular acidosis and urinary tract infection was conducted.

RESULTS

We identified 39 reports on distal renal tubular acidosis or urinary tract infections in association with hyperammonemia published between 1980 and 2017. Hyperammonemia was detected in 13 children with distal renal tubular acidosis and in one adult patient with distal renal tubular acidosis secondary to primary hyperparathyroidism. In these patients a negative relationship was observed between circulating ammonia and bicarbonate levels (P < 0.05). In 31 patients (19 children, 12 adults), an acute urinary tract infection was complicated by acute hyperammonemia and symptoms and signs of acute neuronal dysfunction, such as an altered level of consciousness, convulsions and asterixis, often associated with signs of brain edema, such as anorexia and vomiting. Urea-splitting bacteria were isolated in 28 of the 31 cases. The urinary tract was anatomically or functionally abnormal in 30 of these patients.

CONCLUSIONS

This study reveals that both altered distal renal tubular acidification and urinary tract infection may be associated with relevant hyperammonemia in both children and adults.

'All that glitters is not gold': when hyperammonaemia is not from hepatic aetiology

Hyperammonaemia is often caused by decompensated liver disease. However, non-hepatic causes can sometimes result in hyperammonaemia, severe enough to cause symptoms.We report a case of a 65-year-old man with a history of hypertension and bilateral peripelvic renal cyst who presented with acute confusion. Laboratory investigations revealed hyperammonaemia and normal liver function test. The abdominal ultrasound did not reveal any finding of liver disease or portal-systemic shunting but demonstrated bilateral peripelvic cysts with no hydronephrosis.Hyperammonaemia was attributed to urinary tract infection with a urea-splitting Escherichia coli bacterium.Antibiotic therapy and lactulose were administered. His neurological status rapidly normalised over the next 48 hours, concomitantly with a decrease in ammonia level. Clinician awareness of non-hepatic causes of hyperammonaemic encephalopathy like urinary tract infection can contribute to early diagnosis and timely initiation of appropriate and potentially life-saving treatment including antimicrobial therapy, alleviating urinary obstruction, if present, and lactulose.

Morganella morganii, a non-negligent opportunistic pathogen

Morganella morganii belongs to the tribe Proteeae of the Enterobacteriaceae family. This species is considered as an unusual opportunistic pathogen that mainly causes post-operative wound and urinary tract infections. However, certain clinical M. morganii isolates present resistance to multiple antibiotics by carrying various resistant genes (such as blaNDM-1, and qnrD1), thereby posing a serious challenge for clinical infection control. Moreover, virulence evolution makes M. morganii an important pathogen. Accumulated data have demonstrated that M. morganii can cause various infections, such as sepsis, abscess, purple urine bag syndrome, chorioamnionitis, and cellulitis. This bacterium often results in a high mortality rate in patients with some infections. M. morganii is considered as a non-negligent opportunistic pathogen because of the increased levels of resistance and virulence. In this review, we summarized the epidemiology of M. morganii, particularly on its resistance profile and resistant genes, as well as the disease spectrum and risk factors for its infection.

Noncirrhotic hyperammonaemic encephalopathy

Adult hyperammonaemia is associated with severe liver disease in 90% of cases. In the remainder, noncirrhotic causes should be considered. Measurements of serum ammonia level must be part of the basic work-up in all patients presenting with encephalopathy of unknown origin, even when liver function is normal. Clinician awareness of noncirrhotic hyperammonaemic encephalopathy can contribute to early diagnosis and the initiation of sometimes life-saving treatment. This review focuses on the physiology, aetiology and underlying mechanisms of noncirrhotic hyperammonaemic encephalopathy and discusses the available treatment modalities.

Adult nonhepatic hyperammonemia: a case report and differential diagnosis

This article presents a case report of nonhepatic hyperammonemia, i.e., elevated serum ammonia secondary to a nonhepatic etiology. It then discusses the importance of broadening one's differential diagnosis to include such nonhepatic causes of elevated ammonia levels, and provides a short review of rarer causes of hyperammonemia in the adult population. Treating the underlying condition is the best way to prevent recurrence of hyperammonemia. However, symptomatic treatment should not be delayed while investigating the underlying source.