ABSTRACT
Elizabethkingia spp. bacteria are found in living and non-living things. Elizabethkingia meningoseptica (E. meningoseptica) and Elizabethkingia anophelis (E. anophelis) are the leading species that can cause diseases in humans. Most of the infections (80-87.5%) caused by E. anophelis are hospital-acquired. This bacterium is generally identified as E. meningoseptica by automated systems. In this study, a case of bacteremia due to E. anophelis in a hemodialysis patient is presented. This patient is a 72 years old female who is hospitalized in the intensive care unit. She was referred to the Near East University Hospital from the state hospital with pneumonia. E. anophelis was isolated from the patient’s blood culture by the VITEK-2 automated system. The isolated bacteria were stored at -80 ºC and detected as E. anophelis by matrix-assisted laser desorption ionization time of flight. Success was achieved by adding levofloxacin to the ongoing meropenem treatment in our patient. Although the transmission route of our case with multidrug resistance is not exactly known, it is assumed that the transmission originated from the hospital. In this regard, increasing control measures in hospitals, mainly in water systems, will prevent such infections and deaths. In addition, it is concluded that for treating infections caused by Elizabethkingia, the use of fluoroquinolones should be the first choice.
INTRODUCTION
Bacteria in the genus Elizabethkingia spp. are Gram-negative, aerobic, pale, yellow pigmented, non-motile, non-glucose fermenting, and oxidase positive. They are ubiquitously distributed in nature, including water, soil, sediment, plants, fish, frogs, insects, and some animal digestive tracts. Elizabethkingia meningoseptica, Elizabethkingia anophelis, Elizabethkingia miricola, Elizabethkingia bruuniana, Elizabethkingia ursingii, and Elizabethkingia occulta are known species of bacteria. The leading species that cause diseases in humans are Elizabethkingia meningoseptica (E. meningoseptica) and Elizabethkingia anophelis (E. anophelis).1,2
E. anophelis is a newly discovered bacterium isolated from the gut of Anopheles gambiae mosquito.3 It is reported as an opportunistic bacterial pathogen that causes bacteremia in immunocompromised elderly patients and newborns.4 Moreover, this bacterium can cause meningitis, pneumonia, septic arthritis, osteomyelitis, endocarditis, conjunctivitis, and cholangitis.1 Most of the infections caused by E. anophelis (80%-87.5) are hospital-acquired. These bacteria, which can colonize hospital environments, are resistant to applied decontamination processes. In addition, hospitals are considered to be reservoirs of these bacteria since they can contaminate water systems, solutions, and hospital equipment.1,5
In recent years, an increase in E. anophelis infections that threaten human life has been reported in clinics.6 In society, E. anophelis infection in humans was first observed in 2012 at a hospital in Singapore, when E. anophelis was isolated from five patients with a nosocomial infection. In two of these patients, infection resulted in death due to sepsis.7 According to the literature, several epidemics were seen in Hong Kong, Taiwan, and the United States in the following years.5
Routine phenotypic and biochemical tests often fail to distinguish E. anophelis from other bacteria. At the same time, this bacterium is usually defined as E. meningoseptica by automated systems.5 Additionally, the multi drug resistance (MDR) of the bacterium and the lack of a standard antibiotic susceptibility profile make empirical treatment almost impossible.4 The mortality rate in E. anophelis infections due to MDR is estimated to vary between 24% and 30%.2
Early and accurate determination of appropriate antibiotic susceptibility results is critical and crucial to reduce morbidity and mortality in patients infected with E. anophelis. In our study, a case of bacteremia due to E. anophelis in a hemodialysis patient hospitalized in an intensive care unit (ICU) is presented. In the literature, there is no reported case of E. anophelis that has been found in North Cyprus, and hence this infection is the first Elizabethkingia infection presented in our country.
CASE PRESENTATION
A 72-year-old Ukrainian woman residing in North Cyprus applied to the Near East University Hospital on April 01, 2022, as a referral from Dr. Burhan Nalbantoğlu State Hospital, Nicosia due to respiratory distress. The patient had no fever, was conscious and cooperative. She was also receiving meropenem (3x500 mg) treatment at the hospital she came to. The patient had chronic renal failure and was on regular hemodialysis. First, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) antigen and SARS-CoV-2 RNA polymerase chain reaction test (PCR) were performed on the patient, and she was hospitalized in the general ICU with negative results. Meanwhile, biochemical test were performed from the taken blood and the results were: uric acid (1.7 mg/dL), albumin (2.8 g/dL), amylase (15 U/L), lipase (<4 U/L), and calcium (8.2 mg/dL) were found to be low. In addition, creatinine (2.63 mg/dL), aspartate aminotransferase (AST) (52 U/L), procalcitonin (PCT) (12.26 ng/mL), and C-reactive protein (CRP) (28.63 mg/dL) elevations were noteworthy. In the complete blood count, hemoglobin (12.1 g/dL), and WBCs (4.4x103/µL) levels were found to be normal, but thrombocytopenia (47x103/µL) was detected in the patient.
Considering all these results and respiratory failure, thoracic computed tomography (CT) was performed on April 02, 2022. According to the CT results, massive pleural effusion in the right hemithorax and almost complete loss of aeration in the lower lobe of the right lung were observed. In addition, 14 mm thick pleural fluid was detected in the left hemithorax.
Samples for sputum and blood culture were taken from the patient on the day of hospitalization. The sputum sample was inoculated on blood agar and eosin methylene blue (EMB) agar and incubated for 24-48 hours at 35 ºC. Blood samples were taken from the patient’s right and left arm at an interval of 15 min. The samples (8-10 mL) taken for blood culture were transferred to BD BACTEC Plus Aerobic/F bottles and loaded into the BACTEC 9120 (Becton, Dickinson and Company Sparks, USA) device. Two days later, when positive signals were received from the device, the blood sample was drawn with a sterile syringe from the blood culture bottles and inoculated on blood and EMB agars; the agars were incubated 35 °C for 24-48 hours. With the observation of growth in both sputum and blood cultures, suspensions were prepared from the colonies that grew in line with the manufacturer’s VITEK-2 (BioMerieux, Inc. Durham, USA) compact automated system. In addition, smears were prepared from both colonies and stained with Gram-stain. Structures of Candida species were seen in the Gram-stain of colonies grown in sputum culture and Candida albicans was obtained as a result of VITEK-2. Gram-negative bacilli were observed in smear preparations made from colonies grown in both blood cultures. Upon this, bacteria identification (VITEK-2 GN ID card) and antibiotic susceptibility test (AST) (VITEK-2 AST-N326 card) were performed. AST was evaluated according to the European Committee on Antimicrobial Susceptibility Testing criteria. The result of Elizabethkingia meningoseptica was obtained by the automated system. According to the results of the antibiotic tests, only ciprofloxacin, levofloxacin, and trimethoprim/sulfamethoxazole (SXT) were susceptible. The AST results given by the VITEK-2 automated system of the bacteria are presented in Table 1. Considering the antibiogram, levofloxacin (1x500 mg) was added to the patient’s ongoing meropenem (3x500 mg) treatment. Furthermore, 72 h later, a decrease was observed in our patient’s CRP and PCT levels (13.20 mg/dL and 6.18 ng/mL, respectively). At the end of seventh day, CRP and PCT values were observed as 8.33 mg/dL and 3.31 ng/mL respectively. Our patient had undergone dialysis twice within a week during her stay in the hospital. At the end of a week, the patient returned to the State Hospital again. After that, no information could be obtained from the patient.
E. meningoseptica strains isolated from blood cultures were stocked using bacteria stock tubes (OR-BAK, Ankara, Türkiye) and stored at -80 ºC. Since it is a rare bacterium, the sample was sent to Dokuz Eylül University under the appropriate conditions and the bacterium was detected as E. anophelis by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) (Bruker Daltonics, Bremen, Germany).
An informed consent form was filled by the patient and her consent was obtained, which allowed us to present our case.
DISCUSSION
The case presented in this study is the first reported case of E. anophelis infection detected in Cyprus. Because the patient came to the Near East University Hospital as a referral from a state hospital, the source of the infection is not known exactly. Even though the predominance of this bacterium in the gut microbiota of Anopheles gambiae mosquitoes indicates that mosquitoes can be vectors for transmission, there is no clinical evidence to support this view.2 However, considering that the patient is hospitalized in the ICU of the state hospital and regularly undergoes dialysis, it is possible to think that the infection originates either from the ICU or hemodialysis units. Recent studies suggest that hospital environments act as reservoirs for Elizabethkingia species. In fact, despite the control measures taken in hospitals, it has been proven that the bacterium continues to exist in the water resources of hospitals.8,9 In a study by Kyritsi et al.10, two different Elizabethkingia strains were detected in the water system of the same hospital, three months apart. In view of the data obtained from our study, it is concluded that this bacterium was transmitted to our patient from the hospital environment.
E. anophelis is the dominant strain of the septicemia-causing Elizabethkingia genus and is associated with fulminant complications such as acute pulmonary edema, congestive heart failure, septic shock, and death. E. anophelis infections should always be considered as clinically significant unless proven otherwise. In addition, there exist studies in the literature showing that automated systems such as VITEK-2 misidentify E. anophelis isolates as E. meningoseptica.11 MALDI-TOF systems are extensively used for microbial identification in clinical microbiology laboratories. Unfortunately, systems that are most frequently used for microbial identification like VITEK-2 cannot distinguish Elizabethkingia species. VITEK-2 automated system can detect only E. meningoseptica with its reference database. The lack of species information in the reference databases prevents these platforms from correct recognition of the species of Elizabethkingia. Although MALDI-TOF systems with a large database can reliably identify E. anophelis and E. meningoseptica, these platforms cannot distinguish between the remaining species of the genus Elizabethkingia.12 Moreover, according to the most recent studies, it is emphasized that MALDI-TOF systems are no longer able to accurately identify Elizabethkingia species and therefore 16S rRNA or full genome sequence analyzes are required for accurate identification.13 The strain isolated in this study could not be performed using 16S rRNA or full genome sequence analysis, which can be a limitation of our study. However, showing that this strain exists in Cyprus contributes to clinicians, scientists, and the literature.
E. anophelis has an extensive antibiotic resistance profile, including most penicillins, cefalosporines, carbapenems, aminoglycosides, and macrolide antibiotics. Fluoroquinolones, SXT, and piperacillin/tazobactam are used as first-line therapy for Elizabethkingia infections, but resistance recently complicates treatment. Teng et al. draw attention to SXT resistance in Elizabethkingia species.14 The combination treatment of vancomycin, piperacillin/tazobactam, and ciprofloxacin gave positive results in a newborn case with meningitis and septicemia determined by Baruah et al.11 Nielsen et al.13 isolated E. anophelis from a 76-year-old male patient and applied moxifloxacin and rifampicin treatment for two weeks, which resulted in success. Because they can cross the blood-brain barrier more easily, fluoroquinolones, especially ciprofloxacin, are a good choice for these infections.11 In this study, levofloxacin was combined with meropenem treatment in our patient who presented with septicemia, and as a result, success was achieved.
In conclusion, although the transmission route of our case with multidrug resistance (Table 1) is not known for certain, it is thought that it was caused by the hospital. In this regard, increasing control measures in hospitals, mainly in water systems, will prevent such infections and deaths. For Elizabethkingia typing, if the facilities are sufficient, sequence analysis must be performed. Furthermore, it is concluded that the use of fluoroquinolones should be the first choice for treating infections caused by Elizabethkingia.
MAIN POINTS
• Elizabethkingia anophelis is a rare bacterium and was first isolated in North Cyprus.
• Since it is multiple drug-resistant bacterium, treatment options should be determined correctly.
• It is critical to detect and eliminate the source of contamination, especially in units where immunosuppressed patients are treated, such as intensive care and hemodialysis.
