Multidrug-resistant Klebsiella Pneumoniae Research Articles

The Identification of Phage Vb_1086 of Multidrug-Resistant Klebsiella Pneumoniae and its Synergistic Effects with Ceftriaxone

The Identification of Phage Vb_1086 of Multidrug-Resistant Klebsiella Pneumoniae and its Synergistic Effects with Ceftriaxone

Genetic Analysis, Population Structure, and Characterisation of Multidrug-Resistant Klebsiella pneumoniae from the Al-Hofuf Region of Saudi Arabia.

Multidrug-resistant Klebsiella pneumoniae (MDR-KP) is a major public health problem that is globally associated with disease outbreaks and high mortality rates. As the world seeks solutions to such pathogens, global and regional surveillance is required. The aim of the present study was to examine the antimicrobial susceptibility pattern and clonal relatedness of Klebsiella pneumoniae isolates collected for a period of three years through pulse field gel electrophoresis (PFGE). Isolate IDs, antimicrobial assays, ESBL-production, and minimum inhibitory concentrations (MICs) were examined with the Vitek 2 Compact Automated System. IDs were confirmed by 16S rRNA gene sequencing, with the resulting sequences being deposited in NCBI databases. DNA was extracted and resistance genes were detected by PCR amplification with appropriate primers. Isolates were extensive (31%) and multidrug-resistant (65%). Pulsotype clusters grouped the isolates into 22 band profiles that showed no specific pattern with phenotypes. Of the isolates, 98% were ESBL-KP, 69% were carbapenem-resistant Enterobacteriaceae (CRE) strains, and 72.5% comprised the carriage of two MBLs (SIM and IMP). Integrons (ISAba1, ISAba2, and IS18) were detected in 69% of the MDR-KP. Additionally, OXA-23 was detected in 67% of the isolates. This study therefore demonstrates clonal diversity among clinical K. pneumoniae, confirming that this bacterium has access to an enormous pool of genes that confer high resistance-developing potential.

Topically Applied Bacteriophage to Control Multi-Drug Resistant Klebsiella pneumoniae Infected Wound in a Rat Model.

(Background): Multi-drug-resistant Klebsiella pneumoniae (MDR-KP) has steadily grown beyond antibiotic control. Wound infection kills many patients each year, due to the entry of multi-drug resistant (MDR) bacterial pathogens into the skin gaps. However, a bacteriophage (phage) is considered to be a potential antibiotic alternative for treating bacterial infections. This research aims at isolating and characterizing a specific phage and evaluate its topical activity against MDR-KP isolated from infected wounds. (Methods): A lytic phage ZCKP8 was isolated by using a clinical isolate KP/15 as a host strain then characterized. Additionally, phage was assessed for its in vitro host range, temperature, ultraviolet (UV), and pH sensitivity. The therapeutic efficiency of phage suspension and a phage-impeded gel vehicle were assessed in vivo against a K. pneumoniae infected wound on a rat model. (Result): The phage produced a clear plaque and was classified as Siphoviridae. The phage inhibited KP/15 growth in vitro in a dose-dependent pattern and it was found to resist high temperature (˂70 °C) and was primarily active at pH 5; moreover, it showed UV stability for 45 min. Phage-treated K. pneumoniae inoculated wounds showed the highest healing efficiency by lowering the infection. The quality of the regenerated skin was evidenced via histological examination compared to the untreated control group. (Conclusions): This research represents the evidence of effective phage therapy against MDR-KP.

In Vitro Susceptibility of Multi-Drug Resistant Klebsiellapneumoniae Strains Causing Nosocomial Infections to Fosfomycin. A Comparison of Determination Methods.

Introduction: Over the past few decades, Klebsiella pneumoniae strains increased their pathogenicity and antibiotic resistance, thereby becoming a major therapeutic challenge. One of the few available therapeutic options seems to be intravenous fosfomycin. Unfortunately, the determination of sensitivity to fosfomycin performed in hospital laboratories can pose a significant problem. Therefore, the aim of the present research was to evaluate the activity of fosfomycin against clinical, multidrug-resistant Klebsiella pneumoniae strains isolated from nosocomial infections between 2011 and 2020, as well as to evaluate the methods routinely used in hospital laboratories to assess bacterial susceptibility to this antibiotic. Materials and Methods: 43 multidrug-resistant Klebsiella strains isolates from various infections were tested. All the strains had ESBL enzymes, and 20 also showed the presence of carbapenemases. Susceptibility was determined using the diffusion method (E-test) and the automated system (Phoenix), which were compared with the reference method (agar dilution). Results: For the reference method and for the E-test, the percentage of strains sensitive to fosfomycin was 65%. For the Phoenix system, the percentage of susceptible strains was slightly higher and stood at 72%. The percentage of fosfomycin-resistant strains in the Klebsiella carbapenemase-producing group was higher (45% for the reference method and E-test and 40% for the Phoenix method) than in carbapenemase-negative strains (25%, 25%, and 20%, respectively). Full (100%) susceptibility categorical agreement was achieved for the E-test and the reference method. Agreement between the automated Phoenix system and the reference method reached 86%. Conclusions: Fosfomycin appears to be the antibiotic with a potential for use in the treatment of infections with multidrug-resistant Klebsiella strains. Susceptibility to this drug is exhibited by some strains, which are resistant to colistin and carbapenems. The E-test, unlike the Phoenix method, can be an alternative to the reference method in the routine determination of fosfomycin susceptibility, as it shows agreement in terms of sensitivity categories and only slight differences in MIC values. The Phoenix system, in comparison to the reference method, shows large discrepancies in the MIC values and in the susceptibility category.

Prior Antibiotic Therapy and the Onset of Healthcare-Associated Infections Sustained by Multidrug-Resistant Klebsiella pneumoniae in Intensive Care Unit Patients: A Nested Case-Control Study.

Epidemiological research has demonstrated direct relationships between antibiotic consumption and the emergence of multidrug-resistant (MDR) bacteria. In this nested case–control study, we assessed whether prior exposure to antibiotic therapy and its duration affect the onset of healthcare-associated infections (HAIs) sustained by MDR Klebsiella pneumoniae (MDR-Kp) in intensive care unit patients. Cases were defined as patients who developed an MDR-Kp HAI. Controls matched on sex and the length of intensive care unit (ICU) stay were randomly selected from the at-risk population. Any antibiotic agent received in systemic administration before the onset of infection was considered as antibiotic exposure. Multivariable conditional logistic regression analyses were performed to estimate the effect of prior exposure to each antibiotic class (Model 1) or its duration (Model 2) on the onset of HAIs sustained by MDR-Kp. Overall, 87 cases and 261 gender-matched controls were compared. In Model 1, aminoglycosides and linezolid independently increased the likelihood of developing an MDR-Kp HAI, whereas exposure to both linezolid and penicillins reduced the effect of linezolid alone. In Model 2, cumulative exposure to aminoglycosides increased the likelihood of the outcome, as well as cumulative exposures to penicillins and colistin, while a previous exposure to both penicillins and colistin reduced the influence of the two antibiotic classes alone. Our study confirms that aminoglycosides, penicillins, linezolid, and colistin may play a role in favoring the infections sustained by MDR-Kp. However, several double exposures in the time window before HAI onset seemed to hinder the selective pressure exerted by individual agents.

Prevalence of blaKPC-2, blaKPC-3 and blaKPC-30-Carrying Plasmids in Klebsiella pneumoniae Isolated in a Brazilian Hospital.

Klebsiella pneumoniae carbapenemase (KPC) actively hydrolyzes carbapenems, antibiotics often used a last-line treatment for multidrug-resistant bacteria. KPC clinical relevance resides in its widespread dissemination. In this work, we report the genomic context of KPC coding genes blaKPC-2, blaKPC-3 and blaKPC-30 in multidrug-resistant Klebsiella pneumoniae isolates from Brazil. Plasmids harboring blaKPC-3 and blaKPC-30 were identified. Fifteen additional carbapenem-resistant K. pneumoniae isolates were selected from the same tertiary hospital, collected over a period of 8 years. Their genomes were sequenced in order to evaluate the prevalence and dissemination of blaKPC–harboring plasmids. We found that blaKPC genes were mostly carried by one of two isoforms of transposon Tn4401 (Tn4401a or Tn4401b) that were predominantly located on plasmids highly similar to the previously described plasmid pKPC_FCF3SP (IncN). The identified pKPC_FCF3SP-like plasmids carried either blaKPC-2 or blaKPC-30. Two K. pneumoniae isolates harbored pKpQIL-like (IncFII) plasmids, only recently identified in Brazil; one of them harbored blaKPC-3 in a Tn4401a transposon. Underlining the risk of horizontal spread of KPC coding genes, this study reports the prevalence of blaKPC-2 and the recent spread of blaKPC-3, and blaKPC-30, in association with different isoforms of Tn4401, together with high synteny of plasmid backbones among isolates studied here and in comparison with previous reports.

Multidrug-Resistant Hypervirulent Klebsiella pneumoniae Found Persisting Silently in Infant Gut Microbiota.

Since the spread of multidrug-resistant Klebsiella pneumoniae (MDRKP) strains is considered as a challenge for patients with weakened or suppressed immunity, the emergence of isolates carrying determinants of hypervirulent phenotypes in addition may become a serious problem even for healthy individuals. The aim of this study is an investigation of the nonoutbreak K. pneumoniae emergence occurred in early 2017 at a maternity hospital of Kazan, Russia. Ten bacterial isolates demonstrating multiple drug resistance phenotypes were collected from eight healthy full-term breastfed neonates, observed at the maternity hospital of Kazan, Russia. All the infants and their mothers were dismissed without symptoms or complaints, in a satisfactory condition. Whole-genome shotgun (WGS) sequencing was performed with the purpose to track down a possible spread source(s) and obtain detailed information about resistance determinants and pathogenic potential of the collected isolates. Microdilution tests have confirmed production of extended-spectrum β-lactamases (ESBL) and their resistance to aminoglycoside, β-lactam, fluoroquinolone, sulfonamide, nitrofurantoin, trimethoprim, and fosfomycin antibiotics and Klebsiella phage. The WGS analysis has revealed the genes that are resistant to aminoglycosides, fluoroquinolones, macrolides, sulfonamides, chloramphenicols, tetracyclines, and trimethoprim and ESBL determinants. The pangenome analysis had split the isolates into two phylogenetic clades. The first group, a more heterogeneous clade, was represented by 5 isolates with 4 different in silico multilocus sequence types (MLSTs). The second group contained 5 isolates from infants born vaginally with the single MLST ST23, positive for genes corresponding to hypervirulent phenotypes: yersiniabactin, aerobactin, salmochelin, colibactin, hypermucoid determinants, and specific alleles of K- and O-antigens. The source of the MDRKP spread was not defined. Infected infants have shown no developed disease symptoms.

Combination of polymyxin B and minocycline against multidrug-resistant Klebsiella pneumoniae: interaction quantified by pharmacokinetic/pharmacodynamic modelling from in vitro data

Lack of effective treatment for multidrug-resistant Klebsiella pneumoniae (MDR-Kp) necessitates finding and optimising combination therapies of old antibiotics. The aims of this study were to quantify the combined effect of polymyxin B and minocycline by building an in silico semi-mechanistic pharmacokinetic/pharmacodynamic (PKPD) model and to predict bacterial kinetics when exposed to the drugs alone and in combination at clinically achievable unbound drug concentration–time profiles. A clinical K. pneumoniae strain resistant to polymyxin B [minimum inhibitory concentration (MIC) = 16 mg/L] and minocycline (MIC = 16 mg/L) was selected for extensive in vitro static time–kill experiments. The strain was exposed to concentrations of 0.0625–48 × MIC, with seven samples taken per experiment for viable counts during 0–28 h. These observations allowed the development of the PKPD model. The final PKPD model included drug-induced adaptive resistance for both drugs. Both the minocycline-induced bacterial killing and resistance onset rate constants were increased when polymyxin B was co-administered, whereas polymyxin B parameters were unaffected. Predictions at clinically used dosages from the developed PKPD model showed no or limited antibacterial effect with monotherapy, whilst combination therapy kept bacteria below the starting inoculum for >20 h at high dosages [polymyxin B 2.5 mg/kg + 1.5 mg/kg every 12 h (q12h); minocycline 400 mg + 200 mg q12h, loading + maintenance doses]. This study suggests that polymyxin B and minocycline in combination may be of clinical benefit in the treatment of infections by MDR-Kp and for isolates that are non-susceptible to either drug alone.

Pneumocephalus as a complication of multidrug-resistant Klebsiella Pneumoniae bacteremia in patient with acute myeloid leukemia

Pneumocephalus indicates air in the cranial cavity and commonly results from craniofacial trauma and neurosurgical procedures. Infections can rarely cause pneumocephalus through formation of brain abscess, or as complication of chronic otitis media, or meningitis. Patients might present with headache, fever, change in mental status and diagnosis is confirmed by Brain CT scan. A 51 years old male diagnosed with acute myeloid leukemia (AML) and admitted for fourth cycle of consolidation chemotherapy. He developed prolonged febrile neutropenia and septic shock and multi-organ failure due to Klebsiella Pneumoniae MDR bacteremia. Patient had persistent bacteremia despite being on Meropenem, Colisten, Levofloxacin, Caspofungin, Tigecycline. Due to profound thrombocytopenia, he had severe pulmonary hemorrhage and bilateral diffuse subarachnoid hemorrhage. Repeated CT brain angiography later showed extensive pneumocephalus with finding suggestive of brain death. Ethical approval for case report obtained. Meningitis associated with pneumocephalus is rare and has been reported in gas-forming organisms such as E. coli, Klebsiella Pneumoniae, Bacteroides, mixed aerobic and anaerobic species and streptococcus infection. Treating the underlying meningitis might results in resolution of pneumocephalus, although fatal outcomes were reported. Pneumocephalus secondary to Klebsiella Pneumoniae meningitis is uncommon and one case reported successful treatment using meropenem and amikacin for MDR Klebsiella Pneumoniae meningitis associated with pneumocephalous resulting from chronic otitis media. Pneumocephalus associated with MDR K. pneumonia bacteremia is very rare and had high mortality rate especially in setting of febrile neutropenia with multi-organ failure. Intracerebral hemorrhage in setting of persistent bacteremia might increase the risk of pneumocephalus.

Polymyxin B and Doxycycline for Treatment of Multidrug Resistant Klebsiella Pneumoniae and Staphylococcus Aureus Pneumonia in Intensive Care Unit

Doxycycline is a broad spectrum antibiotic. We hereby report a case report of patients that developed multidrug resistant hospital acquired pneumonia. Patients were treated with Polymyxin B and Doxycycline. From this we want to emphasize that Doxycycline can be used as alternative agent in combination with Polymyxin B for treatment of multidrug resistant pneumonia although there are no large scale studies on combination of Polymyxin B and Doxycycline.

Independent root-cause analysis of contributing factors, including dismantling of 2 duodenoscopes, to investigate an outbreak of multidrug-resistant Klebsiella pneumoniae

Worldwide, an increasing number of duodenoscope-associated outbreaks are reported. The high prevalence rate of contaminated duodenoscopes puts patients undergoing ERCP at risk of exogenous transmission of microorganisms. The contributing factors of the duodenoscope design to contamination are not well understood. This article reports on the investigation after the outbreak of a multidrug-resistant Klebsiella pneumoniae (MRKP) related to 2 Olympus TJF-Q180V duodenoscopes. We conducted a contact patient screening and microbiologic laboratory database search. Reprocessing procedures were audited, and both duodenoscopes were fully dismantled to evaluate all potential contamination factors. Outcomes were reviewed by an experienced independent expert. In total, 102 patients who had undergone an ERCP procedure from January to August 2015 were invited for screening. Cultures were available of 81 patients, yielding 27 MRKP-infected or -colonized patients. Ten patients developed an MRKP-related active infection. The 2 duodenoscopes had attack rates (the number of infected or colonized cases/number of exposed persons) of 35% (17/49) and 29% (7/24), respectively. Identical MRKP isolates were cultured from channel flushes of both duodenoscopes. The review revealed 4 major abnormalities: miscommunication about reprocessing, undetected damaged parts, inadequate repair of duodenoscope damage, and duodenoscope design abnormalities, including the forceps elevator, elevator lever, and instrumentation port sealing. Outbreaks are associated with a combination of factors, including duodenoscope design issues, repair issues, improper cleaning, and systemic monitoring of contamination. To eliminate future duodenoscope-associated infections, a multipronged approach is required, including clear communication by all parties involved, a reliable servicing market, stringent surveillance measures, and eventually new duodenoscope designs and reprocessing procedures with a larger margin of safety.

Polymyxin B-induced skin hyperpigmentation: a rare case report and literature review

BackgroundPolymyxin B (PMB), which is regarded as the ultimate antibacterial treatment against some intractable gram-negative bacteria with its outstanding anti-bacterial activities, inflicts several adverse effects on patients. However, skin hyperpigmentaion (SH) induced by PMB is very rare. Here, we report a case of polymyxin B-induced skin hyperpigmentation (PMB-iSH) in a 21-year-old female. To the best of our knowledge, this is the first case of PMB-iSH in China.Case presentationA 21-year-old female patient with sepsis received the administration of PMB by intravenous injection for the treatment of multi-drug resistant Klebsiella pneumoniae (MDR-KP) infection. She later suffered from a rare adverse drug reaction (ADR), namely PMB-iSH, after 5-day PMB administration during her treatment. There were multiple red rashes spread on the whole body skin at first. With the rashes fading away, SH with dark round spots appeared, associated with no pain or pruritus. The skin of the head and neck was darkened evidently, and dark brown spots were spread on the skin of trunk and limbs. About a month after her admission, urged by the relatives, the patient was transferred back to the local hospital for further treatment in the end, and her skin color didn’t recover to the previous state at that time.ConclusionBoth our case and the literature review highlight that PMB can give rise to SH indeed. Clinicians and pharmacists should attach great importance to this rare pigmentary disorder and further investigation is warranted.

Quantitative study about the role of environmental conditions in the survival capability of multidrug-resistant bacteria.

Healthcare-associated infections (HAIs) caused by multidrug-resistant bacteria (MDRB) are of global concern and hospital textiles can contribute to their transmission. MDRB are able to survive on textiles for more than enough time to spread in the environment. Some studies summarized the effect of environmental factors on the duration of bacterial survival, but it remained an open question how these factors influence the quantity of surviving bacteria in a period of a few days, which is relevant from the perspective of HAIs. Investigating this effect can contribute to better understand the spread of MDRB and the emergence of hospital outbreaks. We investigated quantitatively the survival capability of 15 vancomycin-resistant Enterococcus faecium (VRE), 15 methicillin-resistant Staphylococcus aureus (MRSA), 15 multidrug-resistant Acinetobacter baumannii (MACI) and 15 multidrug-resistant Klebsiella pneumoniae (MRKP) in five environmental conditions using the plate count method. We examined the role of nutrients, textile types, temperature and level of relative humidity on bacterial survival after 1-7days of incubation. Each bacterial group showed higher survival capability on 100% cotton towel than on 100% cotton sheet (P<0.01). MRSAs and VREs showed higher (P<0.01), MACIs showed lower (P=0.02) CFU/swatch values on 100% polyester sheet than on cotton sheet. The survival capability of MRKPs and MRSAs was higher inoculated in nutrient broth than in saline solution (P<0.01). Each bacterial group showed lower survival capability (P<0.01) at body condition (T=35°C, Rh=83%) than at control (T=25°C, Rh=52%). Towels proved to be excellent conditions for each bacteria to survive, however chemical composition of the textiles affected differently the survival of Gram-positive and Gram-negative bacteria. These findings could be useful in searching for the source of outbreaks. Organic contamination of the textiles can increase the survival of desiccation-sensitive bacteria, therefore nutrient-rich inoculating medium is recommended in survival studies.

Invasive infection caused by Klebsiella pneumoniae is a disease affecting patients with high comorbidity and associated with high long-term mortality.

Klebsiella pneumoniae (KP) is after Escherichia coli (EC) the most common gram-negative species causing invasive infections. Herein, we analyzed risk factors and prognosis in invasive infections caused by KP versus EC, in an area with low antimicrobial resistance. Moreover, we compared antimicrobial resistance and relative prevalence of KP and EC (KP/EC-ratio) in different European countries, using EARS-Net data. Adult patients admitted to Karolinska University Hospital 2006–2012 with invasive infection caused by KP (n = 599) were matched regarding sex and age with patients infected by EC. The medical records were retrospectively reviewed. Comorbidity was adjusted for with multivariable analysis. European data were retrieved from the EARS-Net database. No differences were observed in 7- and 30-day mortality between the groups. The 90-day mortality was significantly higher in the KP cohort (26% versus 17%, p<0.001), but not after adjusting for comorbidity. Malignancy was seen in 53% of the patients with KP versus 38% with EC, OR 1.86 (1.34–2.58). A significant increase in the rate of ESBL-production was observed in EC, but not in KP. The KP/EC-ratio remained stable. In contrast, European data showed increasing percentages of isolates non-susceptible to third-generation cephalosporins in EC and KP, and increasing KP/EC-ratio. Invasive infection caused by KP is a disease affecting patients with high comorbidity and associated with high 90-d mortality. The stable KP/EC-ratio and low occurrence of antimicrobial resistance in data from Karolinska University Hospital compared to aggregate data from 20 EARS-Net countries could be related to absence of clonal spread of multidrug-resistant KP.

Genomic Identity of Fluoroquinolone-Resistant blaCTX-M-15-Type ESBL and pMAmpC β-Lactamase Producing Klebsiella pneumoniae from Buffalo Milk, India

We investigated the occurrence of extended-spectrum β-lactamase (ESBL) and AmpC-type β-lactamase (ACBL) producing quinolone-resistant Klebsiella pneumoniae (KP) in milk samples of apparently healthy buffaloes (n = 348) and buffaloes (n = 19) with evidence of subclinical mastitis from seven districts of West Bengal, India. In total, 12 ESBL producing KP were isolated with blaCTX-M-15 gene and 7 of them were ACBL producers, as well. The blaCTX-M-15 genes were carried by transposable element ISEcp1. The plasmid-mediated quinolone resistance genes-qnrS, qnrA, qnrB, qepA, and aac(6')-Ib-cr were detected in five, one, three, four, and one isolate (s), respectively. In addition, eight isolates carried mutation in gyrase (gyrA) and six in topoisomerase IV (parC). Resistance markers/genes for sulfonamide (sul1), tetracycline [tet(A) and tet(B)], and aminoglycoside (aacC2) were also detected in eight, four, and one isolate(s), respectively. The class I integrons identified in five isolates carried aad2/aad5 and dfrA12/dfrA17 gene cassettes. The enterobacterial repetitive intergenic consensus-PCR revealed that all the isolates were genetically diverse and comprised a heterogeneous population. Isolation of multidrug-resistant KP, a typical nosocomial pathogen from buffalo milk, reiterates the need to monitor farm animals for ESBL producing Enterobacteriaceae and emphasizes on judicious use of antibiotics in animal husbandry sector.

Utility of whole-cell repetitive extragenic palindromic sequence-based PCR (REP-PCR) for the rapid detection of nosocomial outbreaks of multidrug resistant organisms: Experience at a tertiary care center in North India

There is a huge need to develop molecular typing methods which are simple to perform, rapid and cost effective to confirm clonality of nosocomial isolates in outbreak situations. The aim of the study was to investigate a hospital outbreak of multi-drug resistant (MDR) Klebsiellapneumoniae septicemia in a paediatric surgery intensive care unit (PSICU) using a repetitive extragenic palindromic polymerase chain reaction (REP-PCR). MDR Klebsiella pneumoniae isolates from an outbreak of nosocomial sepsis were typed byREP-PCR using consensus primers. Isolates from different intensive care units (ICUs) but with similar antibiogram were also genotyped for comparison. A cluster of twelve MDR K Pneumoniae septicemia cases was identified at the PSICU by genotyping using REP-PCR. Surveillance cultures failed to pick up any source of infection. REP-PCR was found to be a rapid and simple tool for investigation outbreaks in hospitals. Due to early detection we could initiate infection control practices with focus on hand washing and prevent the further transmission of the organism.

Characterization of Siphoviridae phage Z and studying its efficacy against multidrug-resistant Klebsiella pneumoniae planktonic cells and biofilm.

Biofilm has many serious consequences for public health and is a major virulence factor contributing to the chronicity of infections. The aim of the current study was to isolate and characterize a bacteriophage that inhibits multidrug-resistant Klebsiella pneumonia (M) in planktonic form as well as biofilm. This phage, designated bacteriophage Z, was isolated from wastewater. Its adsorption rate to its host bacterium was significantly enhanced by MgCl2 and CaCl2. It has a wide range of pH and heat stability. From its one-step growth, latent time and burst size were determined to be 24 min and about 320 virions per cell, respectively. As analysed by transmission electron microscopy, phage Z had an icosahedral head of width 76±10 nm, length 92±14 nm and icosahedron side 38 nm, and a non-contractile tail 200±15 nm long and 14-29 nm wide. It belongs to the family Siphoviridae in the order Caudovirales. Six structural proteins ranging from 18 to 65 kDa in size were revealed by SDS-PAGE. The genome was found to comprise double-stranded DNA with an approximate size of 36 kb. Bacteria were grown in suspension and as biofilms to compare the susceptibility of both phenotypes to the phage lytic action. Phage Z was effective in reducing biofilm biomass after 24 and 48 h, showing more than twofold and threefold reduction, respectively. Biofilm cells and stationary-phase planktonic bacteria were killed at a lower rate than exponential-phase planktonic bacteria.

Risk factors of klebsiella pneumoniae infection and drug resistance

Klebsiella Pneumoniae is a opportunity infection and nosocomial infection bacteria in Enterobacteriaceae, which can lead to serious infection or death. Klebsiella Pneumoniae leads to increased infections proportion in recent years, which resisits to many common antibiotics. Clinical drug resistant strains include Carbapenem-resistant Klebsiella Pneumoniae, Multidrug-resistant Klebsiella Pneumoniae, Extensively drug resistant bacteria and Pandrug-resistant Klebsiella Pneumoniae. Researches beared out that the risk factors of acquiring nosocomial infection of Klebsiella Pneumoniae are state of an illness, time of hospitalization, mechanical ventilation, the kind and number of antibiotics. Key words: Klebsiella Pneumoniae; Infection; Drug resistance

Evaluation of the Efficacy of a Bacteriophage in the Treatment of Pneumonia Induced by Multidrug ResistanceKlebsiella pneumoniaein Mice

Multidrug-resistant Klebsiella pneumoniae (MRKP) has steadily grown beyond antibiotic control. However, a bacteriophage is considered to be a potential antibiotic alternative for treating bacterial infections. In this study, a lytic bacteriophage, phage 1513, was isolated using a clinical MRKP isolate KP 1513 as the host and was characterized. It produced a clear plaque with a halo and was classified as Siphoviridae. It had a short latent period of 30 min, a burst size of 264 and could inhibit KP 1513 growth in vitro with a dose-dependent pattern. Intranasal administration of a single dose of 2 × 109 PFU/mouse 2 h after KP 1513 inoculation was able to protect mice against lethal pneumonia. In a sublethal pneumonia model, phage-treated mice exhibited a lower level of K. pneumoniae burden in the lungs as compared to the untreated control. These mice lost less body weight and exhibited lower levels of inflammatory cytokines in their lungs. Lung lesion conditions were obviously improved by phage therapy. Therefore, phage 1513 has a great effect in vitro and in vivo, which has potential to be used as an alternative to an antibiotic treatment of pneumonia that is caused by the multidrug-resistant K. pneumoniae.

Characterization of extended-spectrum beta-lactamase, carbapenemase, and plasmid quinolone determinants in Klebsiella pneumoniae isolates carrying distinct types of 16S rRNA methylase genes, and their association with mobile genetic elements.

Eighty-four multidrug-resistant Klebsiella pneumoniae (MDR-KP) isolates from a Chinese hospital from January to October 2012 were evaluated to characterize the coexistence of 16S rRNA methylase, extended-spectrum β-lactamase, carbapenemase, and plasmid-mediated quinolone resistance determinants and their association with mobile genetic elements. Among the 84 MDR-KP isolates studied, 19 isolates exhibited high-level resistance to amikacin mediated by the production of the 16S rRNA methylase. They carried 19 armA genes (22.9%) and three rmtB genes (3.6%). CTX-M genes were found in all of the isolates. Among these armA- or rmtB/CTX-M-producing K. pneumoniae isolates, 31.6% carried the carbapenemase genes (blaKPC-2 [26.3%], blaIMP-4 [10.5%], and blaNDM-1 [5.3%]), which made them resistant to imipenem (minimum inhibitory concentration [MIC] ≥16 mg/L). All positive strains possessed qnr-like genes (16 qnrA1, 10 qnrS1, and 7 qnrB4 genes) and 18 harbored an aac(6')-Ib-cr gene. Mobile elements ISEcp1, IS26, ISCR1, ISAba125, and sul-1 integrons were detected in 19/19 (100%), 16/19 (84.2%), 18/19 (94.7%), 9/19 (47.4%), and 18/19 (94.7%) isolates, respectively. The mobilizing elements occurred in different combinations in the study isolates. Majority of armA and qnr genes were in MDR-KP strains carrying integrons containing the ISCR1. Close to 80% of blaTEM-1 and blaSHV-12 were linked to IS26 while ≥90% of blaCTX-Ms and blaCMYs were linked to ISEcp1. ISAba125 was located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants were available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 were cotransferred. This study points to the dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of resistance determinants in collection of clinical K. pneumoniae in China.