A Case of Serratia marcescens Endocarditis in a Nonintravenous Drug-Using Male Patient and Review of Literature

A preliminary exploration on the mechanism of the carbapenem-resistance transformation of Serratia marcescens in vivo

BACKGROUND

The infection of carbapenem-resistant organisms was a huge threat to human health due to their global spread. Dealing with a carbapenem-resistant Serratia marcescens (CRSM) infection poses a significant challenge in clinical settings. This study aims to provide insights into strategies for controlling CRSM infection by exploring the transformation mechanism of carbapenem-resistance.

METHODS

We used whole genome sequencing (WGS) to investigate the mechanism of carbapenem resistance in 14 S. marcescens isolates in vivo. The expression level of related genes and the minimum inhibitory concentration of meropenem (MICMEM) were also evaluated to confirm the mechanism of carbapenem resistance.

RESULTS

Seven groups of S. marcescens, each consisting of two strains, were collected from a hospital and displayed a shift in MICMEM from low to high levels. Homology analysis revealed that the isolates in five groups were significantly different from the remaining two. WGS and experimental evidence indicated that four groups of strains developed carbapenem resistance by acquiring the blaKPC (obtaining group), while two groups (persisting group) increased the expression level of the blaKPC. In contrast, isolates in the last group (missing group) did not carry the blaKPC. All strains possessed multiple β-lactamase genes, including blaCTX-M-14, blaSRT-1, and blaSRT-2. However, only in the missing group, the carbapenem-resistant strain lost an outer membrane protein-encoding gene, leading to increased blaCTX-M-14 expression compared to the carbapenem-susceptible strain.

CONCLUSION

The study findings suggest that S. marcescens strains developed diverse carbapenem resistance in vivo through the evolution of drug resistance, rather than through clone replacement. We hypothesize that carbapenem resistance in S. marcescens was due to certain clonal types with a distinct mechanism.

Serratia marcescens Endocarditis in Prosthetic Valves

Serratia marcescens endocarditis is a rare occurrence. We describe a case of Serratia endocarditis in a patient with a prosthetic valve. The clinical course was complicated by widespread embolic phenomena causing stroke, gangrene of extremities, and septic emboli to the lungs, spleen, and eyes. She was not considered suitable for surgery due to severe consumptive coagulopathy and thrombocytopenia in the setting of widespread emboli. The patient was transitioned to do not resuscitate status and discharged to a long-term care facility with a grave prognosis explained to the family.

Native mitral valve endocarditis associated with KPC producing Serratia marcescens bacteremia successfully treated with mitral valve replacement and ceftazidime-avibactam

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First case of native valve endocarditis due to Klebsiella Pneumomiae carbapenemase (KPC) producing Serratia marcescens.

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Patient underwent mitral valve replacement and was treated with monotherapy ceftazidime-avibactam during 6 weeks.

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Long term treatment with ceftazidime-avibactam appears to be efficacious and well tolerated.

Consistent with global trends of infections due to multiple-drug resistant Gram-negative bacteria, we report the first official case of native mitral valve endocarditis due to multi-resistant Klebsiella Pneumonia Carbapenemase (KPC) producing Serratia marcescens. The patient underwent mitral valve replacement and was successfully treated with monotherapy ceftazidime-avibactam.

A Rare Case of Serratia marcescens Causing Mycotic Aneurysm and Septic Emboli in Intravenous Drug User

There are few literatures highlighting the presence of a mycotic aneurysm in the setting of bloodstream infection by Serratia. A 33-year-old male with a history of Marfan syndrome, mitral valve prolapse, and intravenous drug use (IVDU) presented to the ED with fever, nausea, and non-bloody emesis, and vague abdominal pain with concern for sepsis. With the strong association between IVDU and infective endocarditis, transthoracic and transesophageal echocardiograms were performed and were negative for vegetations. Abdominal CT and positron emission tomography (PET) scan were performed and revealed thrombosis at the first jejunal branch of the superior mesenteric artery (SMA), left renal pole infarct, and superior splenic pole infarct. Following CT angiography for potential thrombolysis, aneurysmal formation was discovered proximal to the filling defect within mid-SMA. Blood cultures drawn at presentation grew Serratia marcescens. The patient was treated with appropriate antibiotic, and recommended indefinite anticoagulation. The patient was then recommended to follow up with vascular surgery within two weeks for repeat abdominal CT angiogram.

Serratia marcescens Endocarditis with Perivalvular Abscess Presenting as Atrioventricular Block

Serratia marcescens is an aerobic, Gram-negative bacillus first identified in 1819 (Yeung et al. 2018). S. marcescens infective endocarditis is extremely rare accounting for only 0.14% of all cases (Phadke and Jacob 2016, Hadano et al. 2012, Nikolakopoulos et al. 2019). We present the case of a 33-year-old male with a past medical history of Hodgkin lymphoma, nonischemic cardiomyopathy ejection fraction of 25-30%, severe aortic stenosis, hepatitis C, and active intravenous (IV) drug abuse who was admitted following a motor vehicle accident. Approximately 10 days into his admission, he developed a 39.5 degree Celsius fever, which prompted collection of blood cultures. These cultures were positive (2 out of 2) for S. marcescens for which he was treated with intravenous cefepime. Soon after this diagnosis, patient developed a complete AV block. Given the instability of the patient, he required emergent placement of a temporary pacing wire. Transesophageal echocardiogram was ordered and revealed an aortic root abscess. Given the comorbidities and active IV drug use, conservative management was pursued. Although rare, trends suggest that this pathogen may be on the rise. Further research is needed to better understand how to effectively manage this pathogen.