Carbapenem resistance in Klebsiella pneumoniae not detected by automated susceptibility testing

Detecting β-lactamase–mediated carbapenem resistance among Klebsiella pneumoniae isolates and other Enterobacteriaceae is an emerging problem. In this study, 15 bla_KPC-positive Klebsiella pneumoniae that showed discrepant results for imipenem and meropenem from 4 New York City hospitals were characterized by isoelectric focusing; broth microdilution (BMD); disk diffusion (DD); and MicroScan, Phoenix, Sensititre, VITEK, and VITEK 2 automated systems. All 15 isolates were either intermediate or resistant to imipenem and meropenem by BMD; 1 was susceptible to imipenem by DD. MicroScan and Phoenix reported 1 (6.7%) and 2 (13.3%) isolates, respectively, as imipenem susceptible. VITEK and VITEK 2 reported 10 (67%) and 5 (33%) isolates, respectively, as imipenem susceptible. By Sensititre, 13 (87%) isolates were susceptible to imipenem, and 12 (80%) were susceptible to meropenem. The VITEK 2 Advanced Expert System changed 2 imipenem MIC results from >16 μg/mL to <2 μg/mL but kept the interpretation as resistant. The recognition of carbapenem-resistant K. pneumoniae continues to challenge automated susceptibility systems.     

First report of New Delhi metallo-β-lactamase-6 (NDM-6) among Klebsiella pneumoniae ST147 strains isolated from dialysis patients in Iran

There has been an alarming health-related concern about the growth of New Delhi metallo-β-lactamase. The aims of this study include the phenotypic detection of β-lactamases and molecular characterization of NDM in Klebsiella pneumoniae isolates in Tehran, Iran. A total of 120 K. pneumoniae isolates were collected from hospitalized haemodialysis patients, Tehran, Iran from March 2014 to February 2017. Antibiotic susceptibility tests were conducted using Kirby-Bauer disc diffusion and Broth Microdilution methods according to Clinical and Laboratory Standards Institute guidelines. Metallo-β-lactamase was detected using the Combined Disc Diffusion Test (CDDT), and production of carbapenemase was screened using the Modified Hodge Test. NDM-producing K. pneumoniae strains were screened for the presence of mcr-1 gene, β-lactamase genes, and 16S rRNA methylase genes by Polymerase Chain Reaction and sequencing. Molecular typing of the strains was determined using Repetitive Sequence Based-PCR and Multilocus Sequence Typing. The bla_NDM-6 gene was detected in 3 (2.5%) out of 120 isolates from dialysis patients. Also, the three isolates were positive for bla_CTX-M-15,bla_TEM extended-spectrum β-lactamase genes, armA type plasmid-mediated 16S rRNA methylase and CMY-type plasmid-mediated AmpC β-lactamase.The isolates were identified as MLST sequence type 147 (ST147). This is the first report of bla_NDM-6 in K. pneumoniae strains, isolated in Iran.     

KlcAHS genes are ubiquitous in clinical,blaKPC-2-positive,Klebsiella pneumoniae isolates

Carbapenemase-producing Klebsiella pneumoniae has emerged and spread widely throughout the world. The mechanisms involved remain unclear. To provide insight, five plasmids were obtained from carbapenemase-producing K. pneumoniae clinical isolates. The five sequences were acquired, aligned and analyzed. In addition to the bla_KPC-2 gene, which encodes beta lactamase, essentially all the plasmids contained a putative anti-restriction protein-encoding gene, KlcA_HS. The KlcA_HS gene was found in 98.2% of the bla_KPC-2-positive, imipenem-resistant K. pneumoniae clinical isolates and in <1% of the bla_KPC-2-negative control group. A searched of the GenBank database indicated that KlcA_HS was mainly submitted by Chinese investigators beginning in 2010. Seventeen different KlcA amino acid sequences were found in the database using the restricting words: KlcA and Klebsiella pneumoniae. These sequences were used to generate a phylogenetic tree via MEGA6 software, revealing a distant evolutionary relationship between KlcA_HS and other KlcAs. The secondary structure of KlcA_HS, predicted with PROMALS3D software, exhibited highly conserved α-helices and β-strands. KlcA_HS expressed anti-restriction activity in vivo.In summary, KlcA_HS genes are ubiquitous in bla_KPC-2-positive Klebsiella pneumoniae clinical isolates collected at Huashan Hospital, China. The KlcA_HS protein possesses a secondary structure similar to that exhibited by anti-restriction proteins and displays anti-restriction activity. As such, KlcA_HS is a probable factor in the accelerated spread of bla_KPC-2 and carbapenem-resistance among clinical, K. pneumoniae isolates.     

In vitro activity of ceftobiprole on 440 Staphylococcus aureus strains isolated from bronchopulmonary infections

Objective

We assessed the in vitro activity of ceftobiprole on 440 Staphylococcus aureus clinical strains isolated from bronchopulmonary infections (2010–2014).

In vitro activity of new antimicrobial agents against glycopeptide-resistant Enterococcus faecium clinical isolates from France between 2006 and 2008

Objective

The aim of this study was to determine the in vitro activity of six new antimicrobial agents against glycopeptide-resistant enterococci (GRE) strains from France.

Methods

Sixty epidemiologically unrelated clinical isolates of Enterococcus faecium (vanA or vanB), received at the National Reference Centre for Enterococci (CNR-Enc) between 2006 and 2008, were studied. The MICs of the following antibiotics were determined by broth microdilution according to Antibiogram Committee of the French Society for Microbiology (CA-SFM) guidelines: quinupristin-dalfopristin (Q-D), linezolid (LZD), daptomycin (DPT), tigecycline (TGC), ceftobiprole (CFT), and telavancin (TLV). Strains were classified using clinical breakpoints recommended by the CA-SFM (Q-D, LZD, TGC), or the Clinical and Laboratory Standards Institute (DPT).

Results

All strains were susceptible to LZD and DPT (MIC₉₀, 4 and 2 μg/ml, respectively) and only a single strain presented intermediate susceptibility to tigecycline (MIC₉₀, 0.25 μg/ml). Thirty percent of strains were resistant to Q-D (MIC₉₀, 4 μg/ml), and CFT was constantly inactive (MIC₉₀, 64 μg/ml). Finally, TLV showed low-level MICs (MIC₉₀, 0.5 μg/ml) against vanB-positive isolates but not against vanA-positive isolates (MIC₉₀, 8 μg/ml).

Conclusion

Although several antibiotics are still active against GRE, it is essential to maintain an active antimicrobial resistance surveillance for these microorganisms considered as a model of multidrug resistance with a potential to transfer resistance to other bacterial species (e.g. Staphylococcus aureus).     

Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods

Objectives

Plasmid-mediated AmpC β-lactamases (PMABLs) and carbapenemases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test performance of various phenotypic methods for detection of these enzymes in Iran.

Methods

A total of 100 K. pneumoniae isolates were collected from clinical specimens obtained in Valiasr Hospital. AmpC production in all isolates was determined using the AmpC disk test, the cephamycin Hodge test, the AmpC Etest, and the boronic acid combined-disk test. In addition, carbapenemase production was determined using the modified Hodge test, the EDTA disk synergy test, and the boronic acid combined-disk test. The performances of various phenotypic methods were evaluated by the comparison of their results with polymerase chain reaction (PCR) method as the gold standard.

Results

Of the 100 isolates, 19 (19%) were demonstrated to harbor the PMABL-resistance gene by the multiplex PCR method. The PCR result indicated the presence of carbapenemase genes in 12 isolates. The performance of various phenotypic tests carried out for detection of carbapenemase-producing isolates varied widely, ranging in sensitivity from 30% to 100% and in specificity from 90.8% to 100%.

Conclusion

This is the first report of MOX-type AmpC β-lactamase and bla_GES in K. pneumoniae in Iran. A comparison of the phenotypic methods showed that a combination of cefoxitin plus boronic acid is optimal for detecting plasmid-mediated AmpC enzymes in K. pneumoniae, whereas the implementation of molecular methods is often complex, requires specially trained personnel, and is associated with higher costs.     

CTX-M β-Lactamase–producing Klebsiella pneumoniae in Suburban New York City,New York,USA

CTX-M extended-spectrum β-lactamase (ESBL)–producing Klebsiella pneumoniae isolates are infrequently reported in the United States. In this study, we analyzed nonduplicate ESBL-producing K. pneumoniae and Escherichia coli clinical isolates collected during 2005–2012 at a tertiary care medical center in suburban New York City, USA, for the presence of bla_CTX-M, bla_SHV, bla_TEM, and bla_KPC genes. Despite a high prevalence of bla_CTX-M genes in ESBL-producing E. coli since 2005, bla_CTX-M genes were not detected in K. pneumoniae until 2009. The prevalence of CTX-M–producing K. pneumoniae increased significantly over time from 1.7% during 2005–2009 to 26.4% during 2010–2012 (p<0.0001). CTX-M-15 was the dominant CTX-M genotype. Pulsed-field gel electrophoresis and multilocus sequence typing revealed high genetic heterogeneities in CTX-M–producing K. pneumoniae isolates. This study demonstrates the recent emergence and polyclonal spread of multidrug resistant CTX-M–producing K. pneumoniae isolates among patients in a hospital setting in the United States.     

Synthesis and in vitro antibacterial activity of 7-(4-alkoxyimino-3-amino-3-methylpiperidin-1-yl)fluoroquinolone derivatives

A series of novel 7-(4-alkoxyimino-3-amino-3-methylpiperidin-1-yl)fluoroquinolone derivatives were designed, synthesized and characterized by ¹H NMR, MS and HRMS. These fluoroquinolones were evaluated for in vitro antibacterial activity against representative Gram-positive and Gram-negative strains. All of the title compounds have considerable activity against the twelve strains, and exhibit exceptional potency in inhibiting the growth of Staphylococcus aureus, Staphylococcus epidermidis and Klebsiella pneumoniae (minimum inhibitory concentration (MIC): 0.06–8 μg/mL). The most active compound 17 is 4-fold more potent than levofloxacin against S. aureus and S. epidermidis, 32-fold more potent than levofloxacin against Streptococcus pneumoniae, and 16-fold more potent than IMB against K. pneumoniae.     

Antimicrobial Resistance of Bacterial Agents of the Upper Respiratory Tract of School Children in Buea, Cameroon

The study was aimed at determining bacterial agents of the upper respiratory tract and the susceptibility patterns of isolates to antibiotics. In total, 200 throat swabs were obtained from students attending different boarding schools within the Buea Municipality and screened to obtain the prevalence of respiratory pathogens and to understand the antibiotic susceptibility patterns of isolates using standard microbiological procedure and the disc-diffusion test. Of the 200 samples screened, 112 (56%) had positive cultures with the dominant bacterial pathogens being Haemophilus influenzae (20%), followed by Streptococcus pneumoniae (15%), Klebsiella pneumoniae (11%), and Staphylococcus aureus (10%). Although 56% of the isolates were recovered from females compared to 44% from males, the difference was not statistically significant (p>0.05). Sixty-seven percent of the pathogens were isolated from the age-group of 10-13 years, 19.6% from the age-group of 14-17 years, and 12.5% from the age-group of 18-21 years. Antibiotic susceptibility testing revealed that gentamicin (92%) and cefuroxime (88.4%) were the most effective antibiotics against the isolates. Generally, susceptibility ranged from 0% to 92% depending on the antibiotic and the species of microorganism. Penicillin had the highest (100%) resistance to all the isolates. The findings revealed that students living in boarding schools in the Buea Municipality were at risk of acquiring upper respiratory tract infections from their peers since the upper respiratory tract of more than 50% of the students was colonized with respiratory pathogens. Although multidrug-resistant strains of organisms were identified, gentamicin and cefuroxime are recommended as the first-line antibiotics of choice against the pathogens. There is, therefore, a need for surveillance of nasopharyngeal carriage of resistant strains of these organisms, especially H. influenzae in unhealthy school children since the vaccine is yet to be introduced in Cameroon. The findings have clinical and epidemiological significance.Key words: Antibiotic resistance, Antibiotics, Bacteria, Child, Drug resistance, Microbial, Influenza, Microbial susceptibility tests, Pneumonia, Respiratory tract infections, Cameroon     

Characterization of resistance genes in 68 ESBL-producing Klebsiella pneumonia in Lebanon

AimWe studied 68 ESBL-producing Klebsiella pneumoniae strains isolated in Lebanon, determined their profile of resistance to antibiotics, and identified 6 ESBL genes.MethodologyThe susceptibility to antibiotics was determined by the disk diffusion method. The MIC of carbapenems and cefepime was determined by the agar dilution method. ESBL genes were detected by PCR.ResultsA percentage of 88.2% and 86.7% of isolates carried the SHV and CTX-M gene respectively; combinations of more than 1 gene of resistance were detected in several isolates. Five strains were resistant to carbapenems; 4/5 carried the OXA-48 gene.ConclusionOur study revealed the emergence of K. pneumoniae ESBL (+) strains carrying several types of genes involved in this phenotype; we also identified carbapenem-resistant strains due to the OXA-48 gene, which are a real threat for public health, especially in Lebanon.     

Worldwide Diversity of Klebsiella pneumoniae That Produce ��-Lactamase blaKPC-2 Gene

Klebsiella pneumoniae isolates that produce carbapenemases (KPCs) are rapidly disseminating worldwide. To determine their genetic background, we investigated 16 bla_KPC-2-harboring K. pneumoniae isolates from 5 countries. The isolates were multidrug resistant, possessed the bla_KPC-2 gene, and differed by additional β-lactamase content. They harbored a naturally chromosome-encoded bla gene (bla_SHV-1 [12.5%], bla_SHV-11 [68.7%], or bla_OKP-A/B [18.8%]) and several acquired and plasmid-encoded genes (bla_TEM-1 [81.3%], bla_CTX-M-2 [31.3%], bla_CTX-M-12 [12.5%], bla_CTX-M-15 [18.7%], and bla_OXA-9 [37.5%]). The bla_KPC-2 gene was always associated with 1 of the Tn4401 isoforms (a, b, or c). Tn4401 was inserted on different-sized plasmids that belonged to different incompatibility groups. Several bla_KPC-containing K. pneumoniae clones were found: 9 different pulsotypes with 1 major (sequence type 258) and 7 minor distinct allelic profiles. Different clones harboring different plasmids but having identical genetic structure, Tn4401, could be at the origin of the worldwide spread of this emerging resistance gene.     

New Delhi Metallo-β-Lactamase–producing Enterobacteriaceae,United States

We characterized 9 New Delhi metallo-β-lactamase–producing Enterobacteriaceae (5 Klebsiella pneumoniae, 2 Escherichia coli, 1 Enterobacter cloacae, 1 Salmonella enterica serovar Senftenberg) isolates identified in the United States and cultured from 8 patients in 5 states during April 2009–March 2011. Isolates were resistant to β-lactams, fluoroquinolones, and aminoglycosides, demonstrated MICs ≤1 µg/mL of colistin and polymyxin, and yielded positive metallo-β-lactamase screening results. Eight isolates had bla_NDM-1, and 1 isolate had a novel allele (bla_NDM-6). All 8 patients had recently been in India or Pakistan, where 6 received inpatient health care. Plasmids carrying bla_NDM frequently carried AmpC or extended spectrum β-lactamase genes. Two K. pneumoniae isolates and a K. pneumoniae isolate from Sweden shared incompatibility group A/C plasmids with indistinguishable restriction patterns and a common bla_NDM fragment; all 3 were multilocus sequence type 14. Restriction profiles of the remaining New Delhi metallo-β-lactamase plasmids, including 2 from the same patient, were diverse.     

Multicentre investigation of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in Bulgarian hospitals – Interregional spread of ST11 NDM-1-producing K. pneumoniae

AimThe aim of this study was to investigate the mechanisms of beta-lactam-resistance and the clonal relatedness of carbapenem-nonsusceptible Klebsiella pneumoniae and Escherichia coli isolates, collected consecutively in eight centers in five Bulgarian cities from November 2014 to March 2018. Carbapenemase-producing enterobacteria were detected in all but one centers. Overall, 104 K. pneumoniae and one E. coli were analysed.Materials and methodsAntimicrobial susceptibility and beta-lactamases were analysed. Conjugation experiments, plasmid fingerprinting and replicon typing, as well as MLST and ERIC-PCR were carried out.ResultsKPC-2 (51%) and NDM-1 (47%) were the main carbapenemases identified. KPC-2 producing K. pneumoniae were classified into 10 MLST-types. The four dominating MLST-types ST29, ST15, ST336 and ST902 comprised 79% of the KPC-2 producers. All but one of the NDM-1 producing isolates belonged to the MLST-type ST11 and were found in seven centers. Furthermore, single K. pneumoniae isolates producing VIM-1 (ST147) and OXA-48 (ST15) were identified. In addition to the carbapenemases, the ESBLs CTX-M-15, CTX-M-3, and SHV-12 as well as AmpC enzyme CMY-4 were found. The FIIAs-replicon-type was found in all KPC-2 producers while the A/C-replicons dominated in NDM-1 producing isolates. The single NDM-1 producing E. coli was determined as MLST-Type ST10 (Warwick scheme).ConclusionThe interregional clonal expansion of NDM-1 producing ST11 K. pneumoniae and the dissemination of bla_KPC-2 carrying plasmids were responsible for the spread of carbapenemase-producing K. pneumoniae in Bulgaria. Our findings highlight the urgency to prevent dissemination of these highly transmissible and dangerous lineages.     

Current trend of pneumococcal serotypes distribution and antibiotic susceptibility pattern in Malaysian hospitals

From January 2008 to December 2009, 433 Streptococcus pneumoniae strains were examined to determine the serotype distribution and susceptibility to selected antibiotics. About 50% of them were invasive isolates. The strains were isolated from patients of all age groups and 33.55% were isolated from children below 5 years. The majority was isolated from blood (48.53%) and other sterile specimens (6.30%). Community acquired pneumonia (41.70%) is the most common diagnosis followed by sepsis (9.54%). Serotyping was done using Pneumotest Plus-Kit and antibiotic susceptibility pattern was determined by modified Kirby-Bauer disk diffusion method and measurement of minimum inhibitory concentration (MIC) using E-test strip. Ten most common serotypes were 19F (15.02%), 6B (10.62%), 19A (6.93%), 14 (6.70%), 1 (5.08%), 6A (5.08%), 23F (4.85%), 18C (3.93%), 3 (2.08%) and 5 (1.85%). Penicillin MIC ranged between ≤0.012-4 μg/ml with MIC₉₀ of 1 μg/ml. Penicillin resistant rate is 31.78%. The majority of penicillin less-susceptible strains belonged to serotype 19F followed by 19A and 6B. Based on the serotypes distribution 22 (44.00%), 28 (56.00%) and 39 (78.00%) of the invasive isolates from children ≤2 years were belonged to serotypes included in the PCV7, PCV10 and PCV13, respectively.     

皖南地区大肠埃希菌与克雷伯菌属ESBLs表型及基因型的检测

目的研究安徽省南部地区3所医院临床分离株中大肠埃希菌和克雷伯菌属超广谱β-内酰胺酶（ESBLs）的产生情况、耐药性及其基因型分布。方法平皿琼脂对倍稀释法测定79株大肠埃希菌和克雷伯菌属对13种抗菌药物的耐药性;采用2005年CLSI推荐方法对收集菌株进行ESBLs确证试验;用PCR方法对产ESBLs菌株使用8对引物进行β-内酰胺酶基因的扩增,扩增产物回收纯化后测序。结果皖南地区3所医院临床分离大肠埃希菌和克雷伯菌属中产ESBLs株的检出率分别为61.5%和45.0%,ESBLs产生株对CRO、CTX、CAZ、CIP、LEV的耐药率分别为81.0%、81.0%、47.6%、71.4%、50.0%,对亚胺培南和美罗培南100%敏感;PCR及测序结果显示产ESBLs菌株中,大肠埃希菌CTX-M1型12株（50.0%）,CTX-M13型11株（45.8%）,OXA1型11株（45.8%）,TEM型19株（79.2%）;克雷伯菌属CTX-M1型4株（22.2%）,CTX-M13型10株（55.6%）,OXA1型、OXA2型、TOHO1型各1株,TEM型9株（50.0%）。结论皖南地区3所医院临床分离大肠埃希菌和克雷伯菌属中产ESBLs株的检出率和对头孢菌素类及喹诺酮类的耐药率均达到相当高水平,应加强对产ESBLs株的临床监测,同时要加强临床对抗菌药物的合理使用。     

Frequency and epidemiology of extended-spectrum β-lactamase-producing Enterobacteriaceae isolates susceptible to third-generation cephalosporins or to aztreonam

Objective

We evaluated among 400 strains of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBLE) the rate of strains categorized as intermediate or resistant to 3rd generation cephalosporins or aztreonam according to the 2011 guidelines of the French Society of Microbiology Antibiogram Committee.

Material and methods

MICs of cefotaxime, ceftazidime, cefepime or aztreonam were determined by the E-test method for isolates with susceptible zones to these antibiotics.

Results

Overall, 109/400 (27.3%) isolates were susceptible to at least one of these 4 agents. Notably, 21.8% of Escherichia coli isolates were susceptible to ceftazidime, and 21.1% of Klebsiella pneumoniae isolates were susceptible to cefepime. Discrepancies between categorization by disk diffusion and MIC determination were observed for aztreonam and cefepime.

Conclusion

These results indicate alternatives to carbapenems for treating infections caused by ESBLE.     

Stenotrophomonas maltophilia susceptibility to ceftazidime-avibactam combination versus ceftazidime alone

ObjectiveTo compare the minimum inhibitory concentrations (MIC) of the ceftazidime-avibactam (CZA) combination versus ceftazidime alone (TZ) for Stenotrophomonas maltophilia.Patients and methodsMIC comparison was performed by E-tests. We assumed that CZA was more effective in vitro than TZ alone when CZA led to a category change from “Resistant” with TZ alone to “Susceptible” or “Intermediate” with CZA, or if the MIC of CZA was at least 4-fold lower than the MIC of TZ for TZ-susceptible isolates.ResultsFor the 54 clinical isolates included in the study, CZA showed better results in terms of the proportion of susceptible isolates (66.7% vs. 38.9%, P < 0.01), MIC₅₀ (2 μg/mL vs. 12 μg/mL, P < 0.05), and MIC distribution. According to our definition, CZA was also more effective in vitro than TZ alone for 50% of the isolates.ConclusionUsing CZA for empirical treatments in severe or polymicrobial infections with S. maltophilia seems appropriate.     

First report of OXA-48-producing Klebsiella pneumoniae strains in Iran

Carbapenem-resistant Enterobacteriaceae are increasingly reported worldwide and cause therapeutic problem in health care facilities. In this study 28 imipenem-resistant K. pneumoniae were examined for expression of carbapenemases by phenotypic and genotypic methods. Modified Hodge Test (MHT), CarbaNP test were used for phenotypic detection, and PCR using specific primers for the detection of bla_OXA-48-, bla_KPC-, bla_NDM- and bla_VIM-type carbapenemases with specific primers were performed. MHT and CarbaNP tests were positive for all of imipenem-resistant K. pneumoniae. The bla_OXA-48 gene was detected in 27/28 isolates. One isolate was positive for the presence of the bla_VIM-4 gene. According to our results NP test and MHT have high sensitivity and specificity for detection of those carbapenemases. This study reports the first cases of OXA-48-producing K. pneumoniae in Iran.     

High resistance of Pseudomonas aeruginosa to paromomycin,an agent used for selective bowel decontamination (SBD)

Background: Paromomycin is used for selective bowel decontamination (SBD) in patients undergoing bone marrow transplantation in many hospitals, but there are no published resistance data for this compound in the recent medical literature. The aim of this study was to investigate the in vitro activity of paromomycin against the common intestinal bacteria E. coli and P. aeruginosa.Methods: 94 E. coli isolates and 77 P. aeruginosa isolates derived from clinical specimens were tested by broth microdilution against paromomycin and amikacin, respectively, following the CLSI recommendations for testing amikacin.Results: 86 of 94 E. coli isolates (91%) and 71 of 77 P. aeruginosa isolates (92%) showed in vitro susceptibility to amikacin (MIC90 for both compounds: 16 µg/ml, range: 1–32 µg/ml for E. coli and 1–>128 µg/ml for P. aeruginosa). Paromomycin was active against 83/94 E. coli isolates (88%; MIC90: 32 µg/ml, range: 2–>128 µg/ml), but showed poor in vitro activity against P. aeruginosa (3/77 isolates susceptible [4%]; MIC90: >128 µg/ml, range: 2–>128 µg/ml).Conclusion: If SBD with inclusion of an aminoglycoside antibiotic is applied, paromomycin should not be used unless local resistance data provide evidence of a sufficient in vitro activity of this compound against P. aeruginosa.     

Molecular characterization of NDM-1-producing Klebsiella pneumoniae ST29, ST347, ST1224, and ST2558 causing sepsis in neonates in a tertiary care hospital of North-East India

Geographical differences can manifest in different spectra of microorganisms and patterns of antibiotic resistance. Considering this, Enterobacteriacae isolated from septicemic neonates from a tertiary care centre in Agartala, India were studied with focus on carbapenem resistance. Two hundred non-duplicate Enterobacteriaceae, of which 12 NDM-1-producing Klebsiella pneumoniae were recovered. Antibiotic susceptibility tests and detection of ESBLs and carbapenemases were performed for all Enterobacteriaceae. For NDM-1-producing isolates, plasmid-mediated quinolone resistance genes, addiction systems, genetic environment of bla_NDM-1 and virulence genes was investigated by PCR. Bacterial clonal relatedness was established using REP-PCR, PFGE, and multi-locus sequence typing (MLST). Transferability of bla_NDM-1 was tested by conjugation and transconjugants were characterized.K. pneumoniae was the primary organism causing sepsis in neonates. Resistance to different antimicrobials was high except for aminoglycosides and carbapenems. bla_CTX-M was present in all isolates. All carbapenem-resistant isolates harboured bla_NDM-1 as the only carbapenemase. bla_CTX-M-15 and qnrS1 were detected in all NDM-1-producing isolates. Plasmid analysis of transconjugants revealed that bla_NDM-1 along with bla_CTX-M-15, qnrS1, qnrB1, aac(6′)-Ib, aac(6′)-Ib-cr and ccdAB or vagCD addiction systems were carried on large IncFIIK conjugative plasmids of varied sizes. bla_NDM-1 was associated with ISAba125 or ISEc33 element at its 5′-end. In addition, isolates also harboured wabG, uge, fimH, mrkD, and entB virulence genes. The NDM-1-producing K. pneumoniae belonged to four distinct clones and were distributed in 4 STs (ST347, ST29, ST2558, and ST1224), of which ST347 was predominant. The association of bla_NDM-1 with diverse STs in K. pneumoniae from neonates indicates the promiscuity of the gene and its widespread dissemination.