Rapid detection of blaOXA in carbapenem-susceptible Acinetobacter radioresistens bacteremia leading to unnecessary antimicrobial administration

Acinetobacter radioresistens and Microbacterium paraoxydans endocarditis in patient with indwelling catheter and metastatic carcinoma

Acinetobacter radioresistens is a rare cause of nosocomial infection and is believed to confer antibiotic resistance to aggressive bacterial species. We present the first reported case of polymicrobial endocarditis caused by A. radioresistens and Microbacterium paraoxydans co-infection, a case of a woman in her late 60s with bacteraemia and ultimate finding of endometrial carcinoma. Bacteraemia with either agent in a previously healthy patient should prompt providers to search for underlying malignancy or immunological problem.We support the use of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for identifying these organisms in cultures, as well as the development of faster isolation techniques through PCR. Furthermore, we advocate for providers to order early antibiotic susceptibility testing, since our patient's Microbacterium sp was not susceptible to meropenem unlike most Microbacterium reported in literature.

Community-Acquired Acinetobacter radioresistens Bacteremia in an Immunocompetent Host

Acinetobacter species are gram-negative coccobacilli ubiquitous in nature and widely distributed in the environment. Acinetobacter baumannii is a bacteria commonly seen in the hospital setting, responsible for causing a wide range of bloodstream infections, urinary tract infections, secondary meningitis, infective endocarditis, and wound infections, and is the cause of outbreaks mainly due to its antimicrobial resistance patterns. The use of broad-spectrum antibiotic coverage with carbapenems is essential in the hospital setting. Therefore, carbapenem-resistant Acinetobacter baumannii (CRAB) poses as a very challenging pathogen. Acinetobacter radioresistens, a rare species in comparison to the more prevalent Acinetobacter baumannii, is an underestimated agent in causing nosocomial infections and also is a potential disseminator of resistance genes. It is also resistant to gamma radiation at 4-8 times higher than other Acinetobacter spp. and is the source of the class D OXA-23 carbapenemase that can confer carbapenem resistance. Therefore, immediate and precise identification of A. radioresistens is crucial for the clinical management of multidrug-resistant bacteremia.

Hepatic hydrothorax: indwelling catheter-related Acinetobacter radioresistens infection

Hepatic hydrothorax, a rare and debilitating complication of cirrhosis, carries high morbidity and mortality. First-line treatment consists of dietary sodium restriction and diuretic therapy. Some patients, mainly those who are refractory to medical management, will require invasive pleural drainage. The authors report the case of a 76-year-old man in a late cirrhotic stage of alcoholic chronic liver disease, presenting with recurrent right-sided hepatic hydrothorax, portal hypertension, hepatosplenomegaly and thrombocytopaenia. After recurrent admissions and complications, the potential for adjusting diuretic therapy was limited. After unsuccessful talc pleurodesis, an indwelling tunnelled pleural catheter was placed with effective symptomatic control. One month later, the patient was readmitted with empyema due to Acinetobacter radioresistens Despite optimised medical and surgical treatment, the patient died 4 weeks later.

Acinetobacter radioresistens infection with bacteremia and pneumonia

Acinetobacter species are non-fermentative Gram-negative coccobacilli that are ubiquitous in the environment. The archetype pathogen within the genus is Acinetobacter baumannii, however, other species have the potential to cause human infection, especially in the hospital setting. We describe a patient with infection due to Acinetobacter radioresistens, a rare agent of human disease, which is often misidentified using biochemical methods. Acinetobacter radioresistens is the source of the Class D OXA-23 carbapenemase that can confer carbapenem resistance in A. baumannii. Therefore, accurate identification of A. radioresistens is important for clinical management and to potentially prevent the spread of carbapenem resistance.

A Decade of Development of Chromogenic Culture Media for Clinical Microbiology in an Era of Molecular Diagnostics

In the last 25 years, chromogenic culture media have found widespread application in diagnostic clinical microbiology. In the last decade, the range of media available to clinical laboratories has expanded greatly, allowing specific detection of additional pathogens, including Pseudomonas aeruginosa, group B streptococci, Clostridium difficile, Campylobacter spp., and Yersinia enterocolitica. New media have also been developed to screen for pathogens with acquired antimicrobial resistance, including vancomycin-resistant enterococci, carbapenem-resistant Acinetobacter spp., and Enterobacteriaceae with extended-spectrum β-lactamases and carbapenemases. This review seeks to explore the utility of chromogenic media in clinical microbiology, with particular attention given to media that have been commercialized in the last decade. The impact of laboratory automation and complementary technologies such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is also assessed. Finally, the review also seeks to demarcate the role of chromogenic media in an era of molecular diagnostics.