Imipenem Resistance Research Articles

Surveillance of Antibiotic Resistance among Hospital- and Community-Acquired Toxigenic Clostridium difficile Isolates over 5-Year Period in Kuwait.

Clostridium difficile infection (CDI) is a leading and an important cause of diarrhea in a healthcare setting especially in industrialized countries. Community-associated CDI appears to add to the burden on healthcare setting problems. The aim of the study was to investigate the antimicrobial resistance of healthcare-associated and community-acquired C. difficile infection over 5 years (2008–2012) in Kuwait. A total of 111 hospital-acquired (HA-CD) and 35 community-acquired Clostridium difficile (CA-CD) clinical isolates from stool of patients with diarrhoea were studied. Antimicrobial susceptibility testing of 15 antimicrobial agents against these pathogens was performed using E test method. There was no evidence of resistance to amoxicillin-clavulanic acid, daptomycin, linezolid, piperacillin-tazobactam, teicoplanin and vancomycin by both HA-CD and CA-CD isolates. Metronidazole had excellent activity against CA-CD but there was a 2.9% resistance rate against HA-CD isolates. Ampicillin, clindamycin, levofloxacin and imipenem resistance rates among the HC-CD vs. CA-CD isolates were 100 vs. 47.4%; 43 vs. 47.4%; 100 vs. 100% and 100 vs. 89%, respectively. An unexpected high rifampicin resistance rate of 15.7% emerged amongst the HA-CD isolates. In conclusion, vancomycin resistance amongst the HA-CD and CA-CD isolates was not encountered in this series but few metronidazole resistant hospital isolates were isolated. High resistance rates of ampicillin, clindamycin, levofloxacin, and imipenem resistance were evident among both CA-CD and HA-CD isolates. Rifampicin resistance is emerging among the HA-CD isolates.

Phenotypic and Molecular Detection of Metallo-Beta-Lactamase Genes Among Imipenem Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Strains Isolated From Patients with Burn Injuries

Background: Pseudomonas aeruginosa and Acinetobacter baumannii are the common causes of nosocomial infections especially among patients with burn injuries. Objectives: The current study aimed to determine the frequency of blaIMP, blaVIM, blaDIM, blaAIM, blaGIM and blaNDM genes among P. aeruginosa and A. baumannii strains isolated from patients with burn injuries hospitalized in Shahid Motahari hospital, Tehran, Iran. Methods: The current cross-sectional study evaluated a total of 309 nonduplicate isolates of P. aeruginosa and 189 isolates of A. baumannii collected from different clinical samples of patients with burn injuries in Shahid Motahari hospital in Tehran, Iran, from 2012 to 2015. Antibiotic susceptibility tests were conducted by Kirby-Bauer disc diffusion and broth microdilution methods according to the clinical and laboratory standards institute (CLSI) guidelines. The frequency of metallo-beta-lactamase (MBL) producers was evaluated by the combination disk diffusion test (CDDT). The blaIMP, blaVIM, blaDIM, blaAIM, blaGIM and blaNDM genes were detected by polymerase chain reaction (PCR) and sequencing techniques. Results: The most effective agent against the studied isolates was colistin. By CDDT, it was found thatamong278 imipenem resistant P. aeruginosa strains, 178(64.02%) were MBL producers. The blaIMP-1 and blaVIM-1 genes were detected in 30(16.8%) and 52(29.2%) of P. aeruginosa isolates, respectively. Result of 187 imipenem resistance A. baumannii strains showed that 85(45.4%) were MBL producers. The blaOXA-51, blaIMP-1 and blaVIM-1 genes were detected in 187(100%), 10(5.3%) and 34(18.18%) of A. baumannii isolates, respectively. Conclusions: The high prevalence of MBLs-producing P. aeruginosa and A. baumannii strains in the study were one of the major concerns.

Imipenem monotherapy for severe abdominal infection caused by Pseudomonas aeruginosa leads to rapid development of imipenem resistance

Imipenem monotherapy for severe abdominal infection caused by Pseudomonas aeruginosa leads to rapid development of imipenem resistance

Rápido aumento de la resistencia a cefalosporinas de 3a generación, imipenem y de la corresistencia en 7.140 aislados de Klebsiella pneumoniae en hemocultivos (2010-2014) según datos de EARS-Net en España

IntroductionAn analysis was made about the evolution of resistance to 3rd generation cephalosporins, imipenem, and other antibiotics in invasive isolates of Klebsiella pneumoniae (K. pneumoniae) according to the Spanish EARS-Net database (2010-2014). MethodsForty-two hospitals from 16 Autonomous Communities with an approximate population coverage of 33% participated. ResultsA total 7,140 pneumoniae corresponding to the same number of patients were studied. Overall resistance percentages (I+R) were: cefotaxime 15.8%, ceftazidime 13.7%, imipenem 1.7%, ciprofloxacin 20.1%, tobramycin 14.1%, gentamicin 10.4%, and amikacin 1.9%.Resistance to 3rd generation cephalosporins increased from 9.8% (2010) to 19% (2014); to ciprofloxacin from 15.4% (2010) to 19.6% (2014); to gentamicin from 6.2% (2010) to 10.3% (2014) and to tobramycin from 7.1% (2010) to 14.2% (2014) (p<.001 in all cases). Combined resistance to 3rd generation cephalosporins, ciprofloxacin, and aminoglycosides increased from 3.3% (2010) to 9.7% (2014) (p<.001). Resistance to imipenem also increased from 0.27% (2010) to 3.46% (2014) (p<.001). A total of 121 isolates were resistant to imipenem, of which 104 (86%) produced carbapenemases: 74 OXA-48, 14 VIM, 9 KPC (6 KPC-2 and 3 KPC-3), 6 IMP, and 1 GES. ConclusionsOver the 5 year period (2010-2014), resistance to 3rd generation cephalosporins in invasive K. pneumoniae in Spain has doubled. The combined resistance to 3rd generation cephalosporins, ciprofloxacin, and aminoglycosides has tripled, and imipenem resistance has increased almost 13 times, mostly due to the spread of carbapenemase-producing isolates.

Resistant mechanisms and molecular epidemiology of imipenem-resistant Acinetobacter baumannii.

The aim of the study was to investigate the resistant mechanisms and homology of imipenem-resistant Acinetobacter baumannii (A. baumannii). A total of 46 non-duplicate imipenem-resistant A. baumannii clinical isolates were collected from three tertiary hospitals between July, 2011 and June, 2012. The minimal inhibitory concentrations (MICs) of antimicrobial agents were determined using the agar dilution method. Phenylalanine-arginine β-naphthylamide was used to detect the presence of the efflux pump-mediated resistant mechanism. Polymerase chain reaction was employed to amplify genes associated with drug resistance, including β-lactamase genes, efflux pump genes and outer membrane protein gene CarO. A few amplicons were randomly selected and sequenced. Multilocus sequence analysis (MLST) was employed in typing A. baumanni. A. baumannii was resistant to imipenem, simultaneously showing resistance to several other antimicrobials. In addition, 13 A. baumannii were found to mediate drug resistance through operation of the efflux pump. Of the various drug resistance genes tested, blaOXA-51 was present in 46 isolates, blaOXA-23 gene was present in 44 isolates and blaNDM gene was found in only one strain. Other drug resistant-associated genes, including blaKPC, blaIMP, blaOXA-24, blaOXA-58, blaSHV, blaGIM and blaVIM were not detected. Mutation of adeS and outer membrane protein gene CarO were found in a few of the imipenem-resistant isolates. The MLST analysis revealed that all 46 clinical isolates were clustered into 11 genotypes and the most frequent genotype was ST208. In conclusion, β-lactamase genes, genes involved in efflux pump and mutation of outer membrane protein encoding gene may be important in mediating imipenem resistance in A. baumannii. Of the 11 different genotypes, ST11 was shared by the majority of A. baumannii, which may be due to horizontal transfer of patients from hospitals.

Ciprofloxacin and imipenem resistance and cross-resistance in Pseudomonas aeruginosa: A single institution experience.

We conducted a pilot study to evaluate the resistance and cross-resistance of Pseudomonas aeruginosa to imipenem and ciprofloxacin. Our results highlight the importance of the judicious use of antibiotics, particularly fluoroquinolones, amidst the limited arsenal of effective antibiotics against Pseudomonas aeruginosa and the risk of cross-resistance induction.

DNA fingerprinting and antimicrobial susceptibility pattern of clinical and environmental Acinetobacter baumannii isolates: a multicentre study

Background and aim: The aims of this study were to establish antibiotic profile and the molecular epidemiology of Acinetobacter baumannii isolates, with considering the effectiveness of control infection measures across three hospitals in the Kurdistan, west part of Iran. Methods: Fifty-four A. baumannii isolates were collected from patients and environmental specimens. Antibiotic susceptibility patterns (Antibio-type) were evaluated for 17 different antibiotics and MIC for imipenem was done. Isolates were assessed for the presence of metallo-beta-lactamases (MBLs), class 1 and 2 integrons, and integrated gene cassettes and bla OXA-likefamilies genes. Repetitive-sequence-based PCR (REP-PCR) was done for analysing clonality and relativeness of isolates (REP-type). Results: Antibiotic susceptibility patterns distinguished 11 distinct Antibio-types and REP-PCR showed three clusters with 20 subclusters, mostly belonged to two clonal subgroups, A1 and B1. bla OXA-51 and bla OXA-23 were detected in 100% (54/54) and 52% (28/54), respectively, while bla OXA-24-like and bla OXA-58 were not present in isolates. MBLs were not detected, but, however, high rate of imipenem resistance was observed (52%). MIC90 of imipenem was 16 mg/ml. Class 1 integrons were detected in 11% (6/54) of isolates followed by 24% (13/54) of class 2. Both classes of integron genes were detected in 15% (8/54) of isolates. Integrated gene cassettes were in low level (11% of class 1 harboring isolates). Two arrays of gene cassettes were revealed, dfrA5-like and dfrA17-aadA5. Conclusion: Infection control surveillance should be considered as a serious manner, even the superficial eradication of hospital acquired pathogens. MBL genes were not induced carbapenem resistance in studied hospital settings, but bla OXA-51 & 23 contributed in imipenem resistant. Integrons had a little share in resistance of A. baumannii isolates.

Emergence of Storm Resistant Mechanisms in Pseudomonas aeruginosa Isolated from Burn Patients Hospitalized in Ghotbeddin Shirazi Burn Hospital

Introduction: Pseudomonas aeruginosa is a bacterium has capability of presenting different policies against antimicrobial agents. These capacities make this bacterium as one of the most important cause of nosocomial infection especially among burned patients. Methods: In this cross sectional study, total of 253 hospitalized burned patients (During September 2013 to November 2014) in Ghotbeddin Shirazi were evaluated for P. aeruginosa. Confirmed isolates tested for Metallo-β-lactamase (MBLs) producing and related genes bla IMPI, II , bla SPM , bla KHM , bla VIM , efflux pump activity, and OprD mutations. Results: From total of 56 (22%) P. aeruginosa isolates, 32 (57.14%) were MBLs while in genetic evaluation, only bla IMPII, bla KHM and bla VIM genes were detected. While 52 (92.8%) isolates had MexAB-OprM gene but 44(78.6%) isolates had efflux pump activity. In OprD sequencing evaluation it has been proved that the most imipenem resistance isolates have mutations in this related gene. Based on the results it has been proved that the circulating P. aeruginosa isolates in Shiraz burn center are armed with the most potential resistant mechanisms. Conclusion: According to that the most isolates have the potential of express different mechanisms of resistance, it is highly recommended to evaluate the circulating infectious agents periodically and determine their resistant algorithm to control them before being resistant and being dominant in health centers.

Prevalence and Risk Factors associated with Extended Spectrum Beta Lactamase Producing Escherichia coli and Klebsiella pneumoniae Isolates in Hospitalized Patients in Kashan (Iran).

IntroductionProduction of extended spectrum beta lactamase (ESBL) is an important mechanism of antimicrobial resistance in Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) isolates. This study was performed to determine the prevalence and risk factors associated with ESBL producing strains of E. coli and K. pneumoniae.MethodsIn this cross-sectional study, 250 strains (134 E. coli and 116 K. pneumoniae) were obtained, and ESBL producing isolates were detected by the combination disk test in Shahid Beheshti Hospital in Kashan, Iran, from February 2012 to June 2013. Antimicrobial resistance was screened by the disk diffusion method and was confirmed by E-test. Furthermore, risk factors of ESBL producing E. coli and K. pneumoniae microorganisms were determined. Data were analyzed by SPSS version 16, using descriptive statistics, chi-squared, independent-samples t-test, and logistic regression analysis.ResultsOne hundred and two (40.8%) of all strains were ESBL producers, of which 54 (52.9%) were E. coli and 48 (47.1%) were K. pneumoniae (p = 0.86). Furthermore, 40.3% of E. coli and 41.4% of K. pneumoniae isolates were ESBL producers (p = 0.86). The most antimicrobial resistance was to ampicillin, and no imipenem resistance was detected. Risk factors for ESBL producing E. coli included admission duration exceeding 7 days (p = 0.011) and antibiotic use in the last month (p < 0.001), and the associated risk factor for ESBL producing K. pneumoniae was antibiotic use during the recent month (p = 0.002).ConclusionThis study identified a relatively high prevalence of ESBL production among E. coli and K. pneumoniae strains. Furthermore, anti-bimicrobial use and admission duration were risk factors for ESBL producing isolates. Therefore, more comprehensive investigations are needed for the development of new strategies to control the dissemination of these microbes.

Insertion sequence ISRP10 inactivation of the oprD gene in imipenem-resistant Pseudomonas aeruginosa clinical isolates

Carbapenem resistance mechanisms were investigated in 32 imipenem-resistant Pseudomonas aeruginosa clinical isolates recovered from hospitalised children. Sequence analysis revealed that 31 of the isolates had an insertion sequence element ISRP10 disrupting the porin gene oprD, demonstrating that ISRP10 inactivation of oprD conferred imipenem resistance in the majority of the isolates. Multilocus sequence typing (MLST) was used to discriminate the isolates. In total, 11 sequence types (STs) were identified including 3 novel STs, and 68.3% (28/41) of the tested strains were characterised as clone ST253. In combination with random amplified polymorphic DNA (RAPD) analysis, the imipenem-resistant isolates displayed a relatively high degree of genetic variability and were unlikely associated with nosocomial infections.

Risk Factors Associated With Imipenem-Resistance Among Isolated Gram -Negative Bacteria From Patients in Sanandaj Hospitals, Iran

Background: The use of imipenem antibiotics against Gram-negative bacteria is growing, but the incidence of imipenem-resistant bacteria is also increasing. Objectives: The aim of this study was to determine the risk factors for imipenem resistance in patients with Gram-negative bacteria infections. Patients and Methods: An imipenem minimum inhibitory concentrations (MIC) test was done using the E-test, and a survey of different risk factors of imipenem resistance in 374 patients who were infected solely by Gram-negative bacteria was performed. Results: Of the 374 isolated, 134 were imipenem resistant, and 240 were sensitive to imipenem. The resistance rate was more common in males and in patients with intensive care unit (ICU) admission, trauma-induced infections, a history of antibiotic use, the need for ventilator support, or central venous catheter insertion, and in nosocomial infections. Conclusions: Our results showed the rate of effects of different risk factors on imipenem resistance. Regarding the studied risk factors, appropriate programs must be set in place to control and prevent imipenem resistance in Gram-negative bacteria.

Trends in the distribution and antimicrobial susceptibility of causative pathogens of device-associated infection in Korean intensive care units from 2006 to 2013: results from the Korean Nosocomial Infections Surveillance System (KONIS)

For all countries, information on pathogens causing healthcare-associated infections is important in order to develop proper strategies for preventing and treating nosocomial infections. To assess the change in frequencies and antimicrobial resistance of pathogens causing device-associated infections (DAIs) in intensive care units (ICUs) in South Korea between July 2006 and June 2014. Data from the Korean Nosocomial Infections Surveillance System (KONIS) were analysed, including three major DAI types in ICUs. The frequency of Gram-negative bacteria gradually increased for central line-associated bloodstream infection (CLABSI) and ventilator-associated pneumonia (VAP) (from 24.6% to 32.6% and from 52.8% to 73.5%, respectively). By contrast, the frequency of Gram-positive bacteria decreased from 58.6% to 49.2% for CLABSI, and from 44.3% to 23.8% for VAP (P < 0.001). Staphylococcus aureus was the most frequent causative pathogen in CLABSI throughout the surveillance period, but for VAP was replaced as the most frequent pathogen by Acinetobacter baumannii as of 2010. Candida albicans was the most frequent pathogen for catheter-associated urinary tract infection. The meticillin resistance rate in S. aureus decreased from 95% to 90.2% (P < 0.001); amikacin resistance in Klebsiella pneumoniae and Escherichia coli decreased from 43.8% to 14.7% and from 15.0% to 1.8%, respectively (P < 0.001); imipenem resistance in A. baumannii increased from 52.9% to 89.8% (P < 0.001). The proportion of Gram-negative bacteria as nosocomial pathogens for CLABSI and VAP has increased. The prevalence of A. baumannii causing DAIs in Korean ICUs has increased rapidly, as has the rate of carbapenem resistance in these bacteria.

Evaluation of Risk Factors for Antibiotic Resistance in Patients with Nosocomial Infections Caused by Pseudomonas aeruginosa.

Background. Pseudomonas aeruginosa (P. aeruginosa) is resistant to various antibiotics and can cause serious nosocomial infections with high morbidity and mortality. In this clinical study, we investigated the risk factors in patients who were diagnosed with P. aeruginosa-related nosocomial infection. Methods. A retrospective case control study including patients with P. aeruginosa-related nosocomial infection. Patients who were resistant to any of the six antibiotics (imipenem, meropenem, piperacillin-tazobactam, ciprofloxacin, amikacin, and ceftazidime) constituted the study group. Results. One hundred and twenty isolates were isolated. Various risk factors were detected for each antibiotic in the univariate analysis. In the multivariate analysis, previous cefazolin use was found as an independent risk factor for the development of imipenem resistance (OR = 3.33; CI 95% [1.11–10.0]; p = 0.03), whereas previous cerebrovascular attack (OR = 3.57; CI 95% [1.31–9.76]; p = 0.01) and previous meropenem use (OR = 4.13; CI 95% [1.21–14.07]; p = 0.02) were independent factors for the development of meropenem resistance. For the development of resistance to ciprofloxacin, hospitalization in the neurology intensive care unit (OR = 4.24; CI 95% [1.5–11.98]; p = 0.006) and mechanical ventilator application (OR = 11.7; CI 95% [2.24–61.45]; p = 0.004) were independent risk factors. Conclusion. The meticulous application of contact measures can decrease the rate of nosocomial infections.

Antimicrobial Effect of Imipenem-Functionalized Fe2O3 Nanoparticles on Pseudomonas aeruginosa Producing Metallo β-lactamases.

Resistant strains of Pseudomonas aeruginosa to imipenem was medical treatment problem, especially in burnt units of hospitals. This study was conducted to evaluate the antimicrobial effect of Fe2O3 nanoparticles alone and functionalized with imipenem on P. aeruginosa starins producing metallo β-lactamases (MBL). A disk diffusion method was used to isolate a clinical P. aeruginosa producing Metallo β-lactamases with imipenem resistance. The minimum inhibitory concentration (MIC) of Fe2O3 nanoparticles and imipenem were calculated against the bacteria. The antimicrobial effect of nanoparticles functionalized with the antibiotic was determined. Standard strain of P. aeruginosa ATCC: 27853 was used as control. The clinical sample was resistant to imipenem (up to 28 μg.mL-1). Similarly, MIC of the nanoparticles against the isolate was 160 μg.mL-1. Subsequently, the combination of 16 pg.mL-1 of antibiotic with 80 μg.mL-1 of Fe2O3 nanoparticles were able to inhibit the growth of the isolate. Fe2O3 nanoparticles functionalized with imipenem can impair antibiotic resistance mechanisms of bacteria as it can make the imipenem resistant the aforementioned bacterium more susceptible to weaker concentrations of antibiotic. It also has its own antibacterial effect in certain concentrations.

Investigation of OprD Porin Protein Levels in Carbapenem-Resistant Pseudomonas aeruginosa Isolates.

Background:The Pseudomonas aeruginosa porin OprD is a substrate-specific porin that facilitates the diffusion of basic amino acids, small peptides, and carbapenems into the cell. OprD-mediated resistance occurs as a result of decreased transcriptional expression of oprD and/or loss of function mutations that disrupt protein activity.Objectives:In this study, we examined the level of oprD expression in P. aeruginosa clinical isolates to determine the contribution of OprD porins in carbapenem resistance.Materials and Methods:Included strains were divided into two groups, comprised of multidrug-resistant (MDR) and isolated carbapenem-resistant (ICR) strains. The transcription product level of oprD was identified using real-time polymerase chain reaction (qPCR).Results:Of the 18 clinical isolates, a decrease in the oprD level was found to be significant in 13 isolates. Nine of eighteen isolates with a significant decrease were determined in the first group and comprised MDR isolates that showed a statistically significant difference compared with the ICR group (P = 0.001). In the ICR group, oprD levels were found to be significantly low in 4 isolates. Six different patterns were determined by comparing band profiles in AP-PCR.Conclusions:Although the data support the idea that the basic mechanism of imipenem resistance could be via the loss of oprD, they do not fully explain the role of oprD and indicate that other mechanisms may play an important role. Additionally, the significant decrease in the oprD levels in MDR strains suggests that oprD also plays a role in the emergence of both carbapenem and non-carbapenem resistance.

Identification and Characterization of Imipenem-ResistantKlebsiella pneumoniaeand SusceptibleKlebsiella variicolaIsolates Obtained from the Same Patient

Klebsiella variicola, a bacterium closely genetically related to Klebsiella pneumoniae, is commonly misidentified as K. pneumoniae by biochemical tests. To distinguish between the two bacteria, phylogenetic analysis of the rpoB gene and the identification of unique genes in both bacterial species by multiplex-polymerase chain reaction (PCR) provide the means to reliably identify and genotype K. variicola. In recent years, K. variicola has been described both as the cause of an intrahospital outbreak in a pediatric hospital, which resulted in sepsis in inpatients, and as a frequent cause of bloodstream infections. In the present study, K. pneumoniae and K. variicola were isolated from a unique patient displaying different antimicrobial susceptibility phenotypes and different genotypes of virulence determinants. Eight clinical isolates were obtained at different time intervals; all during a 5-month period. The isolates were identified as K. pneumoniae by an automated identification system. The clinical (biochemical test) and molecular (multiplex-PCR and rpoB gene) characterization identified imipenem resistance in the first six K. pneumoniae ST258 isolates, which encode the SHV-12 cephalosporinase and KPC-3 carbapenemase genes. The two last remaining isolates corresponded to susceptible K. variicola. The bacterial species showed a specific profile of virulence-associated determinants, specifically the fimA, fimH, and ecpRAB fimbrial-encoding genes identified only in K. pneumoniae isolates. However, the entb (enterobactin), mrkD (fimbrial adhesin), uge (epimerase), ureA (urease), and wabG (transferase) genes were shared between both bacterial species. Recent studies attribute a higher mortality rate to K. variicola than to K. pneumonia. This work highlights the identification of K. pneumoniae and the closely related K. variicola isolated from the same patient. The value of distinguishing between these two bacterial species is in their clinical significance, their different phenotypes and genotypes, and the fact that they can be isolated from the same patient.

Multidrug-Resistant Escherichia coli and Klebsiella pneumoniae Isolated From Patients in Kashan, Iran.

Background:Escherichia coli and Klebsiella pneumoniae are common human pathogens that cause a wide spectrum of infections. Antimicrobial resistance is a basic obstacle in the management of these infections which has different patterns in various regions.Objectives:In this study, the antibiotic resistance patterns and risk factors for multidrug-resistant (MDR) E. coli and K. pneumoniae were determined.Patients and Methods:In this cross-sectional study, a total of 250 isolates (134 E. coli and 116 K. pneumoniae) were collected and antimicrobial resistances to ampicillin, amoxicillin-clavulanic acid, amikacin, gentamycin, ceftriaxone, ceftazidime, ciprofloxacin and imipenem were evaluated by disc diffusion method and confirmed by E-test. Moreover, risk factors for MDR E. coli and K. pneumoniae were also detected.Results:The mean ages of the culture-positive cases of E. coli and K. pneumoniae were 33.39 ± 24.42 and 36.54 ± 24.66 years, respectively (P = 0.31); 137 (54.8%) cases were male and 113 (45.2%) were female (P = 0.53). Nineteen (14.2%) isolates of E. coli and 12 (10.3%) isolates of K. pneumoniae were sensitive to all the evaluated antibiotics. The prevalence of MDR E. coli and MDR K. pneumoniae was 50% and 46.6%, respectively (P = 0.59). The highest resistance for both strains was to ampicillin and no imipenem resistance was seen. The risk factors for MDR E. coli were admission history during the recent three months (P = 0.043) and antibiotic use in the previous month (P = 0.03); for MDR K. pneumoniae, they were admission in the pediatric ward (P = 0.016), surgical ward (P = 0.019), or gynecology ward (P = 0.12), admission duration of > seven days, and antibiotic use during the past month (P = 0.04).Conclusions:The prevalence of multidrug resistance was high compared with developed countries, and history of admission, antibiotic use, admission duration and admission wards were the risk factors for multidrug resistance.

Efflux Pump Inhibitor Phenylalanine-Arginine Β-Naphthylamide Effect on the Minimum Inhibitory Concentration of Imipenem in Acinetobacter baumannii Strains Isolated From Hospitalized Patients in Shahid Motahari Burn Hospital, Tehran, Iran.

Background:Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients.Objectives:The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients.Materials and Methods:This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing.Results:In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%).Conclusions:The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections.

Multidrug resistant Klebsiella pneumoniae in NICU – what next? Trend of antibiotic resistance

Multidrug resistant (MDR) Klebsiella pneumoniae an increasing cause of neonatal sepsis in India. This observational study was designed to monitor temporal change in prevalence of K. pneumoniae as a causative organism for neonatal sepsis and its sensitivity pattern. The time period was divided into four time frames of six months each (designated A (1/10/2006-31/03/2007) to D (1/04/2008-30/09/2008)). K. pneumoniae isolation in all cultures sent from neonatal intensive care units doubled in time frame D (6.3%) compared to time frame A (3.0). Similarly, the percentage of total positive cultures in the neonatal intensive care unit that were K. pneumoniae also doubled (27.8% in A to 55.6% in D). K. pneumoniae sepsis tripled in inborn neonates (15.4% in A to 47.1% in D). Incidence of MDR K. pneumoniae increased from 0% in time frame A to 76.5% in time frame D. Resistance against ampicillin and third generation cephalosporins (cefotaxime and ceftazidime) remained 100% in all time frames. Carbapenem (meropenem and imipenem) resistance increased from 0% in time frame A and B to 41.2% in time frame D. Death due to K. pneumoniae sepsis showed brisk resurgence in time frame D (17.6%) compared to time frame C (10%). Lower gestational age and birth weight were associated with higher mortality. MDR K. pneumoniae is emerging as a more frequent cause of neonatal sepsis. There is an dincreasing threat of combined quinolone and carbapenem resistant MDR K. pneumoniae.

Efflux Pump Inhibitor Phenylalanine-Arginine Β-Naphthylamide Effect on the Minimum Inhibitory Concentration of Imipenem in Acinetobacter baumannii Strains Isolated From Hospitalized Patients in Shahid Motahari Burn Hospital, Tehran, Iran

Background:: Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients. Objectives:: The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients. Materials and Methods:: This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing. Results:: In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%). Conclusions:: The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections.