Emergence of Mycobacterium simiae: A retrospective study from a tertiary care center in Lebanon

Abstract

ObjectiveThe objective of this study is to describe the clinical significance of Mycobacterium simiae at a major tertiary care center in Lebanon.MethodsThis is a retrospective study of patients with positive cultures for M. simiae isolated between 2004 and 2016 at the American University of Beirut Medical Center.ResultsThis study included 103 M. simiae isolates recovered from 51 patients. Their mean age was 62.7 years. The majority were males and smokers. Specimens were mostly from respiratory sources (97%). Common comorbidities included chronic lung disease (such as chronic obstructive pulmonary disease), solid tumor, systemic disease, and diabetes mellitus. Productive cough and dyspnea were the most common symptoms. Frequent radiographic findings were infiltrates and nodules on chest X-ray and nodules, infiltrates, and bronchiectasis on chest computed tomography scan. Among 18 tested isolates, 5.8% were resistant to clarithromycin, 11.7% to amikacin, and 70–100% to other antimicrobials. Out of 13 patients receiving early treatment, 5 noted improvement, one had recurrence of symptoms, two received alternative diagnosis, and five died. Two of those deaths were related to M. simiae. Common treatment regimens included clarithromycin in different combinations with trimethoprim-sulfamethoxazole, moxifloxacin, and amikacin. Moreover, clofazimine was used in only two patients whose isolates were resistant to all but one agent. Duration of treatment ranged from 6–24 months.ConclusionIn Lebanon, M. simiae is increasingly encountered with true infection rates of at least 47%. Furthermore, the prevalence of multidrug resistance among the Lebanese M. simiae isolates is very high limiting the treatment options.

Emergence of multidrug-resistantMycobacterium simiae: An in vitro study from a regional tuberculosis reference laboratory in Iran

“…We hypothesize that the high rate of M. simiae in Iran, may be due to the contamination of water supplies with this pathogen, a finding that was previously reported in studies conducted in Iran [18,19]. Temperature and humidity have also been reported to be associated with NTM infections [16,20]. Another explanatory factor may be the presence of underlying diseases among patients with M. simiae as described by Coolen-Allou…”

“…Van Ingen et al in the Netherlands, showed resistant rates of 86% to amikacin, 77% to ciprofloxacin, 36% to moxifloxacin and 9% to clarithromycin in clinical isolates of M. simiae [7]. M. simiae isolates from Hamieh et al, study in the Lebanon were mostly susceptible to amikacin and clarithromycin and less susceptible to moxifloxacin and ciprofloxacin [16]. Likewise…”

“…simiae as an emerging pathogen in Iran accounts for more than 30.0% of all pulmonary diseases caused by NTM in our study. Based on the previous studies, 10 to 47% of the patients with NTM had true M. simiae infection [5,15,16]. We have recently indicated the clinical isolation of M. simiae by some studies in Iran, but the ecology behind this is not well understood [17].…”

Non-tuberculous mycobacteria profiles and their anti-mycobacterial resistance at a major medical center in Lebanon

“…This species has been associated with humid weather and water niches, as reported for Cuba, Arizona, Texas, Iran, Gaza and Israel [13]. The humid weather in Lebanon, a Mediterranean costal country, may also explain the high prevalence of M. simiae in this area of the world [13,14]. Few other countries in the Middle East and the Gulf region reported on the recovery of this species, albeit with lower rates such as Oman (8%) and Turkey (2.1%) [8].…”

“…In Lebanon, a couple of published articles addressed NTM, mostly as case reports [9][10][11][12][13][14] but none has comprehensively revealed the present species nor their antimicrobial resistance (AMR) profiles. Besides, the recovery of NTMs has been increasing, with rates reaching 55 to 67% among isolated mycobacteria, as noted for instance in our medical center over the last five years.…”