tetA and tetB Genes in Klebsiella Pneumoniae Isolated From Clinical Samples

Occurrence and mechanisms of tigecycline resistance in carbapenem- and colistin-resistant Klebsiella pneumoniae in Thailand

Tigecycline has been regarded as one of the most important last-resort antibiotics for the treatment of infections caused by extensively drug-resistant (XDR) bacteria, particularly carbapenem- and colistin-resistant Klebsiella pneumoniae (C-C-RKP). However, reports on tigecycline resistance have been growing. Overall, ~ 4000 K. pneumoniae clinical isolates were collected over a five-year period (2017-2021), in which 240 isolates of C-C-RKP were investigated. Most of these isolates (91.7%) were resistant to tigecycline. Notably, a high-risk clone of ST16 was predominantly identified, which was associated with the co-harboring of blaNDM-1 and blaOXA-232 genes. Their major mechanism of tigecycline resistance was the overexpression of efflux pump acrB gene and its regulator RamA, which was caused by mutations in RamR (M184V, Y59C, I141T, A28T, C99/C100 insertion), in RamR binding site (PI) of ramA gene (C139T), in MarR (S82G), and/or in AcrR (L154R, R13Q). Interestingly, four isolates of ST147 carried the mutated tet(A) efflux pump gene. To our knowledge, this is the first report on the prevalence and mechanisms of tigecycline resistance in C-C-RKP isolated from Thailand. The high incidence of tigecycline resistance observed among C-C-RKP in this study reflects an ongoing evolution of XDR bacteria against the last-resort antibiotics, which demands urgent action.

Evaluation of the Ability to Form Biofilms in KPC-Producing and ESBL-Producing Klebsiella pneumoniae Isolated from Clinical Samples

The appearance of Klebsiella pneumoniae strains producing extended-spectrum β-lactamase (ESBL), and carbapenemase (KPC) has turned into a significant public health issue. ESBL- and KPC-producing K. pneumoniae's ability to form biofilms is a significant concern as it can promote the spread of antibiotic resistance and prolong infections in healthcare facilities. A total of 45 K. pneumoniae strains were isolated from human infections. Antibiograms were performed for 17 antibiotics, ESBL production was tested by Etest ESBL PM/PML, a rapid test was used to detect KPC carbapenemases, and resistance genes were detected by PCR. Biofilm production was detected by the microtiter plate method. A total of 73% of multidrug resistance was found, with the highest resistance rates to ampicillin, trimethoprim-sulfamethoxazole, cefotaxime, amoxicillin-clavulanic acid, and aztreonam. Simultaneously, the most effective antibiotics were tetracycline and amikacin. bla_CTX-M, bla_TEM, bla_SHV, aac(3)-II, aadA1, tetA, cmlA, catA, gyrA, gyrB, parC, sul1, sul2, sul3, bla_KPC, bla_OXA, and bla_PER genes were detected. Biofilm production showed that 80% of K. pneumoniae strains were biofilm producers. Most ESBL- and KPC-producing isolates were weak biofilm producers (40.0% and 60.0%, respectively). There was no correlation between the ability to form stronger biofilms and the presence of ESBL and KPC enzymes in K. pneumoniae isolates.

Revisiting ESKAPE Pathogens: virulence, resistance, and combating strategies focusing on quorum sensing

The human-bacterial association is long-known and well-established in terms of both augmentations of human health and attenuation. However, the growing incidents of nosocomial infections caused by the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) call for a much deeper understanding of these organisms. Adopting a holistic approach that includes the science of infection and the recent advancements in preventing and treating infections is imperative in designing novel intervention strategies against ESKAPE pathogens. In this regard, this review captures the ingenious strategies commissioned by these master players, which are teamed up against the defenses of the human team, that are equally, if not more, versatile and potent through an analogy. We have taken a basketball match as our analogy, dividing the human and bacterial species into two teams playing with the ball of health. Through this analogy, we make the concept of infectious biology more accessible.

Multidrug Resistance in Integron Bearing Klebsiella pneumoniae isolated from Alexandria University Hospitals, Egypt

Klebsiella pneumoniae is by far one of the most common Enterobacteriaceae associated with hospital-acquired infections. The dissemination of multi drug resistant Klebsiella pneumoniae is causing difficulty to treat infections worldwide. Of additional concern, multi drug resistant Klebsiella pneumoniae acquires and transfers antibiotic resistance genes among other bacterial isolates. Integrons have the main role in the acquisition as well as dissemination of resistance genes. Accordingly we aimed to investigate the frequency of resistance genes sul1, sul2, tetA, tetB and aac (3) IIa, class one (int1 gene) and class two integrons(int2 gene) in Klebsiella pneumoniae clinical isolates from four major hospitals in Alexandria, Egypt using Polymerase Chain Reaction. In addition we aimed to evaluate the association between multidrug resistance and presence of integrons in hospital-acquired Klebsiella pneumoniae in our hospitals. To the best of our knowledge, there is little information about integrons and acquisition of multiple antibiotic resistance in Klebsiella pneumoniae in hospitals in Alexandria, Egypt. In this study 76 isolates were resistant to sulphamethoxazole /trimethoprim. Of these 38 isolates (50%) harbored both genes sul1 and sul2 genes. 42 isolates out of the 60 (70%) isolates that showed resistance to tetracycline were tetA or tetB positive. The prevalence of int1 gene among all isolates tested was 90%, while only one isolate harbored the int2 gene (1%). Our results were indicative of the high prevalence of multidrug resistant Klebsiella pneumoniae as well as integrons that were found to play an essential role in the dissemination of antibiotic resistance genes in our hospitals.

Emergence of bla NDM-1 Harboring Klebsiella pneumoniae ST29 and ST11 in Veterinary Settings and Waste of Pakistan

Introduction

Intense livestock farming practices enforcing the farmers to use antibiotics as food supplements on a routine basis. Aberrant use of antibiotics is associated with the emergence of antibiotics resistance and resistant superbugs. Keeping in view the current scenario, the present study was designed for the first time from Pakistan with a specific aim to estimate the prevalence of the carbapenem-resistant Klebsiella pneumoniae in veterinary settings and the waste in Pakistan.

Methods

A total of 138 samples from various veterinary sources were collected by employing a nonprobability sampling technique. Isolation and phenotypic identification of carbapenem-resistant K. pneumoniae were performed according to the CLSI standard. Molecular detection of various antibiotic resistance genes (ARGs) was done through PCR by using specific primers against each ARG. According to the pasture scheme, the multilocus sequence typing (MLST) was performed to characterize the K. pneumoniae sequence types (STs).

Results

According to the results of the study, overall 9.4% (13/138) isolates were confirmed carbapenem-resistant K. pneumoniae. Among various carbapenem ARGs particularly, the bla _NDM-1 was found in 92.3% (12/13) isolates followed by bla _OXA-48 84.6% (11/13). MLST results revealed that overall 3 STs were found in the study which includes ST29, ST11, and ST258. Taking together, this is the first study to our best knowledge which demonstrated the prevalence of carbapenem-resistant K. pneumoniae and its various STs prevalent in veterinary settings and the waste of Pakistan.

Conclusion

Based on the above-mentioned facts, we suggested that veterinary settings and waste are the potential source and reservoir of carbapenem-resistant K. pneumoniae, which may be disseminated to the environment and ultimately can affect the public and companion livestock health.

Biogenic Synthesis of ZnO Nanoparticles and Its Potential Use as Antimicrobial Agent Against Multidrug-Resistant Pathogens

In case of Escherichia coli and Klebsiella pneumoniae infection, the increased prominence of multidrug-resistance strains has become the greatest challenge in the urinary tract disease treatment. Therefore, the 16S rRNA sequencing of multidrug-resistant strains was performed, in addition to those of plasmids and genes responsible for multidrug resistance. These strains showed containing responsible genes Sulfonamides sul1, Tetracycline Tet(A), Tetracycline Tet(B), chloramphenicol catA1, β-lactams blaSHV, and cmlA. Also, the strains demonstrated resistance to at least 10 types of antibiotics or more due to carrying various plasmids. For increasing the level of public health in daily life and treatment of multidrug-resistant bacteria, the nanomedicine was employed. Consequently, ZnO nanoparticles (ZnONPs-E) were synthesized by employing supernatant of Escherichia hermannii strain isolated from raw milk source. The E. hermannii strain produces high concentration of ZnONPs-E compared to other strains so we used it in this study. This ZnONPs-E has a minimal inhibitory concentration (MIC) ranged from the concentration 10 μg/ml to 40 μg/ml against E. coli and K. pneumoniae, respectively. The antimicrobial efficiency of ZnONPs-E was 40 µg/ml and it was superior to the reported values in literature. Moreover, SEM results evident for distorted membrane morphology, blebbing of membrane, cell elongation, and leakage of cellular contents due to ZnONPs-E activity against tested bacteria. These results indicated that the ZnONPs-E exhibited interesting antimicrobial activity against pathogenic extended-spectrum β-lactamases (ESBLs) strains. The present study revealed that the active components entered in biosynthesis of ZnONPs-E pave the way to lead its effective nano-medical and drug delivery applications.

Characterization of Klebsiella isolates obtained from clinical mastitis cases in dairy cattle

Klebsiella spp. are important opportunistic pathogens commonly defined as environmental clinical mastitis agents. Despite Klebsiella mastitis being clinically impairing in cows and costly to the industry, only a few studies describe Klebsiella isolated from mastitis cases. The aim of this work was to characterize species of Klebsiella involved in clinical mastitis cases in Canada. Klebsiella isolated from clinical mastitis cases (n = 53) were identified to the species level using a biochemical test panel and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The rpoB gene sequence was used as the gold standard method and identified Klebsiella pneumoniae (n = 40), Klebsiella oxytoca (n = 9), Raoultella ornithinolytica (n = 2), and Raoultella planticola (n = 2). Raoultella, a genus closely related to Klebsiella, was also accurately identified using mass spectrometry but not via biochemical testing. Using the disc diffusion technique, 31 (58%) isolates were found to be susceptible to all antimicrobials tested (n = 18). The remaining 22 (42%) isolates were resistant to 1 or more of the following antimicrobials: kanamycin (2%), streptomycin (38%), spectinomycin (13%), sulfisoxazole (13%), and tetracycline (19%). The following antimicrobial resistance genes were identified: tetA, tetB, sul1, strA/strB, and aadA. Random amplified polymorphic DNA revealed the majority of our isolates as unrelated and having different patterns, indicating environmental contamination as the primary source of infection. All isolates were shown to be biofilm producers. In conclusion, although antimicrobial resistance was low for both Klebsiella and Raoultella species, genetically related Klebsiella spp. isolates appeared to be more resistant.

Phylogenetic relationships, virulence and antimicrobial resistance properties of Klebsiella sp. isolated from pet turtles in Korea

Klebsiella sp. are responsible for a multitude of infectious diseases in both humans and animals. In this study, phylogenetic relationships, virulence and antimicrobial resistance gene properties of 16 Klebsiella sp. isolated from 49 pet turtles were investigated. The isolates including Klebsiella oxytoca (n = 13) and Klebsiella pneumoniae (n = 3) were identified using 16S rRNA gene sequencing and each species formed distinct clusters in the neighbour-joining phylogenetic tree. The prevalence of virulence genes including ureC (100%) and kfu (68·75%) was observed among the isolates using Polymerase chain reaction (PCR) assay. The fimH, mrkD and rmpA genes were detected in all K. pneumoniae while these were absent in every K. oxytoca isolate. In antimicrobial susceptibility testing, high resistance rates were observed against ampicillin (100%) and cephalothin (62·50%). The resistance rates against imipenem, tetracycline, trimethoprim/sulfamethoxazole, nalidixic acid and ciprofloxacin were 12·50, 12·50, 12·50, 6·25 and 6·25% respectively. The presence of antimicrobial resistance genes such as plasmid-mediated quinolone resistance (PMQR) [qnrB (37·50%), qnrA (31·25%), qnrS (12·50%) and aac(6')-Ib-cr (12·50%)], extended-spectrum β-lactamase (ESBL) [bla_CTX-M (18·75%)], β-lactamase [bla_SHV-1 (18·75%)] and tetracycline resistance [tetE (12·50%)] was observed. The results revealed that pet turtle-borne Klebsiella sp. may carry different types of virulence and antimicrobial resistance genes which represents a potential threat to public health. SIGNIFICANCE AND IMPACT OF THE STUDY: Klebsiella sp. are nonmotile Gram-negative bacteria that are found in different environments. The virulence and antimicrobial resistance properties of pet turtle-borne Klebsiella sp. have not been studied before. Phylogenetic relationships, virulence traits and antimicrobial resistance profiles of pet turtle-borne Klebsiella sp. were characterized for the first time in Korea. Multiple virulence and antimicrobial resistance genes were observed among the isolates. The occurrence of virulence and antimicrobial resistance determinants in Klebsiella sp. may represent a potential threat to public health.