چاپ صفحه |  صفحه نخست سامانه |  چکیده مقاله |  نویسندگان |  دانلود مقاله | دانشگاه علوم پزشکی تبریز |
| To the Editor The emergency of the community-spread of NDM-producing Klebsiella pneumoniae was the message of a recent report in the present journal [1]. An NDM-1 producing isolate showed decreased sensitivity to all beta-lactams and also resistance to fluoroquinolones and aminoglycosides. Multidrug-resistant, carbapenemase-producing K. pneumoniae is a global public health problem of highest concern [2]. New Delhi Metallo-beta-lactamase 1 (NDM-1) which is a transferable molecular class B carbapenemase (zinc Metallo-b-lactamase) got its fame when a Swedish patient of Indian origin traveled to New Delhi, India, and acquired a urinary tract infection caused by a carbapenem-resistant K. pneumoniae strain [3]. The carbapenemase harbored bacteria was then contemplated to be associated with the Indian subcontinent, but it moved faster than anyone would even anticipate and many cases throughout the world were reported positive [4]. Now, the presence of NDM-1 has been reported from other countries, including the UK, Asia, Europe, Africa and North America and comprehend both community and hospital acquisition [4]. Molecular typing and virulence gene analysis are powerful tools that can shed more light on K. pneumoniae isolates and thereby on the type of infections they cause [2]. We here attempted to identify K. pneumoniae clinical isolates for the production of NDM-1 carbapenemase and then characterize them for antibiotic resistance pattern, serotyping, harbouring of the biofilm genes and virulence factor. In total, 61 K. pneumoniae isolates collected from various clinical specimens were initially identified by biochemical tests [5] and later confirmed at a molecular level by polymerase chain reaction (PCR) using primers as described earlier [6]. The f12 phenotype (hyperviscosous strain) was defined when a colony touched with the loop and lifted vertically from the surface of the agar plate, produced a string-like growth between the loop and the surface of the plate [7]. These isolates were assessed for the production of NDM-1 carbapenemase by PCR using primers as depicted previously [8]. The patient’s demographic data and underlying diseases were analysed. The activity of ciprofloxacin, amikacin, gentamicin, ceftazidime, cefotaxime, piperacillin- tazobactam, nitrofurantoin (tested only for urinary isolates), imipenem, meropenem, co-trimoxazole and levofloxacin against NDM-1 positive isolates of K. pneumoniae was analysed by disk-diffusion method [9]. The presence of K5, K20 and K54 capsular serotypes and biofilm formation genes (kpn and mrkD) was detected by multiplex PCR [6,8]. PCR was used to detect the frequency of virulence genes namely, wabG, ycfM, entB, uge, iutA, wcaG, rmpA, cnf-1, hly, allS and fimH to determine the pathogenicity pattern of NDM-1 positive isolates [8]. Among all, K. pneumoniae isolates confirmed at a molecular level, 12 (19.7%) isolates were found as blaNDM-1 positive. Seven of these 12 were isolated from females. Among the 12 patients, only two provided a travel history to India and Pakistan, while others did not have any travel account. One patient succumbed to the infection. The clinical source of these 12 isolates comprised of: urine (n¼7; 58.3%), wound (n¼2; 16.6%), blood (n¼2; 16.6%) and body fluids (n¼1; 8.3%). In the current study, most (7/12 (58.3%)) blaNDM-1 positive strains were isolated from clinical specimens of patients with a renal disease admitted to the urology ward. Antimicrobial susceptibility testing disclosed that all blaNDM-1 positive isolates were multidrug-resistant except for an isolate which belonged to K54 serotype and was isolated from the emergency ward. Among 61 isolates, the blaNDM-1 positive isolates were significantly associated with resistance to gentamicin (n¼9/12;p¼.04), amikacin (n¼8/12; p¼.04), imipenem and meropenem (each n¼8/12; p<.01). In terms of capsular serotyping, eight isolates (66.6%) were typeable and K54 was the most prevalent serotype (n¼6; 50%). The pathogenicity pattern of 12 isolates is depicted in Table 1. kpn and mrkD as biofilm encoding genes were positive in 66.6% of the isolates. Virulence factors namely, uge (100%), wabG (91.6%), ycfM (91.6%) and entB (91.6%) encoding the capsule, capsule lipoprotein, external membrane protein and enterobactin production [8], respectively, had higher prevalence compared to wcaG, rmpA and iutA (siderophore) genes with frequency of 16.6%, 8.3% and 8.3%, respectively. Capsule associated genes (wabG, uge and ycfM) enhance the ability of the bacteria to evade phagocytosis by macrophages and thus promote infection [8]. It is now well documented that hypervirulent (hvKP) strains are characterized by several virulence factors including capsule polysaccharide, fimbriae and siderophores [2]. The rmpA gene is a plasmid-borne regulator of extracellular polysaccharide synthesis and associated with the hypermucoviscous phenotype and FimH and mrkD, the fimbrial adhesins which mediate binding to the extracellular matrix to form biofilm [2]. cnf-1 (cytotoxic necrotizing factor), hly (haemolysin), allS (associated with allantoin metabolism) and fimH were not found in any of blaNDM-1 positive isolates [8]. Our results imply that NDM-1-producing K. pneumoniae strains act as potent pathogens due to the acquisition of biofilm and capsule associated factors. In conclusion, we here report NDM-1-producing K. pneumoniae obtained from routine clinical specimens of patients who had no travel history to any repository countries. The isolates did not represent communityacquired or nosocomial outbreak as the specimens were collected over a six month period of time and patients did not have any epidemiological connection. Our results emphasize a dilemma about the spread of NDM-1-producing isolates. May be, travel in the past transferred the plasmid. NDM-1 positive isolates provided multidrug-resistant pattern and were mostly isolates from the urine of patients with renal complications. The multidrug resistance pattern of the blaNDM-1 positive K. pneumoniae isolates is a source of deep concern. A high prevalence of NDM-1-producing isolates with strong capsular mediated pathogenicity and high biofilm production capability is a major health threat and warrants a need for further surveillance. |
| نویسنده | نفر چندم مقاله |
|---|---|
| آلکا حسنی | اول |
| القار سلطانی | دوم |
| محمد آهنگرزاده رضایی | سوم |
| اکبر حسنی | چهارم |
| پوریا قلیزاده | پنجم |
| آرزو نوعی اسکویی | ششم |
| نام فایل | تاریخ درج فایل | اندازه فایل | دانلود |
|---|---|---|---|
| NDM-1.pdf | 1399/06/02 | 571089 | دانلود |
