Prevalence of Extended-Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae Isolates in Nosocomial and Community-Acquired Urinary Tract Infections

Molecular Characterization of Antibiotic Resistance and Genetic Diversity of Klebsiella pneumoniae Strains

The aims of this study were the molecular characterization of antibiotic resistance and genotyping of Klebsiella pneumoniae strains isolated from clinical cases in Tehran, Iran. A total of 100 different types of clinical human samples were collected from a major teaching hospital in Tehran, Iran. Bacterial isolates were identified using standard microbiological tests. Antimicrobial susceptibility testing was done according to the latest CLSI guidelines. PCR was used to amplify the gyrA gene in quinolone-resistant isolates and sequencing was performed for the detection of probable mutations between the isolates. The occurrence of plasmid-mediated quinolone resistance genes (qnrA, qnrB, and qnrS) was also investigated by PCR. Finally, genotyping of the strains was performed by PFGE in a standard condition. The susceptibility pattern revealed a high and low level of resistance against meropenem (20%) and trimethoprim (37%), respectively. PCR and sequencing detected mutation in the gyrA gene in 51% of quinolone-resistant K. pneumoniae. According to the susceptibility report, among nalidixic acid-resistant strains, 60.5%, 50%, and 42.9% of isolates contained qnrA, qnrB, and qnrS, respectively. Among ciprofloxacin-resistant strains, qnrA was the most frequent PMQR gene. The PFGE differentiated the strains into 31 different genetic clusters so that the highest number (7/66) was in category A. Our results indicated that the frequency of resistance to various antibiotics particularly trimethoprim, nalidixic acid, and cefoxitin are increasing. The presence of qnr (S and A) genes and point mutation of the gyrA gene were likely to be responsible for the resistance toward nalidixic acid and ciprofloxacin in our strains. Also, the results obtained from genotyping indicated that the K. pneumoniae strains isolated in this study belonged to the diverse clones.

Evaluation of a lateral flow immunoassay to detect CTX-M extended-spectrum β-lactamases (ESBL) directly from positive blood cultures for its potential use in Antimicrobial Stewardship programs

OBJECTIVE

Bloodstream infections (BSI) caused by extended-spectrum beta-lactamases Enterobacteriaceae (ESBL-E) are associated with high rates of treatment failure and increased mortality, especially when appropriate antimicrobial therapy is delayed. Our aim was to evaluate the anticipation of ESBLs detection and the potential improvement of the time response of the Vitek 2 System (BioMérieux; France).

METHODS

We compared this lateral flow immunoassay when used directly on fluid from positive blood cultures to the VITEK2 AST system. We evaluated 80 isolates, 61 tested directly on fluid from positive blood cultures and 19 tested on fluid from blood cultures spiked with known ESBL positive and negative organisms.

RESULTS

The concordance between the CTX-LFIA and the reference method (Vitek 2) had a Cohen´s Kappa coefficient of 0.97, indicating a particularly good correlation between both compared methods.

CONCLUSIONS

This lateral flow immunoassay can be more rapid than the Vitek 2 for earlier presumptive identification of CTX-M ESBLs and can be useful to anticipate results and the adjustment of antimicrobial therapy.

The Role of Bacteriophages as Important Reservoirs of Extended-Spectrum Beta-Lactamase Genes in Azerbaijan Hospitals

Aims: The aim of this study was to investigate the role of resident bacteriophages in hospital effluents, as a potential reservoir of extended-spectrum beta-lactamase (ESBL) genes. Methods: Effluent samples were collected from four major medical centers in Azerbaijan. Phage enrichments were prepared and purified using standard subculturing, amplification, and phage purification protocols. DNA materials from phage stocks and bacterial isolates were examined for the presence of ESBL genes using polymerase chain reaction. Restriction fragment length polymorphism (RFLP) profiles were used for the construction of a dendrogram and cluster analysis. Results: A total of 112 phage enrichments were obtained from 48 effluent samples against resident bacterial hosts. A total of 95 nonduplicate Gram-negative isolates were recovered from effluent samples. The most common isolate was Escherichia coli (n = 48), followed by Klebsiella pneumoniae (n = 18), Pseudomonas spp. (n = 9), and Enterobacter cloacae (n = 6). Thirty-two EcoRV-RFLP profiles consisting of ∼4 to 20 bands were obtained for the 40 E. coli phage enrichments. ESBL genes were detected in 23 of 40 (57.5%) E. coli phage enrichments, including bla_CTX-M (n = 15), bla_TEM (n = 14), and bla_SHV (n = 6). Detected genes in phage enrichments against resident hosts other than E. coli include bla_TEM (n = 4), bla_CTX-M (n = 3), and bla_SHV (n = 1). A total of 63 (66.3%) bacterial isolates were positive for tested genes, including bla_CTX-M (n = 32), bla_TEM (n = 61), and bla_SHV (n = 12). The present research provides a strong evidence for the possible role of bacteriophages in antimicrobial resistance genes circulation in Azerbaijan clinical settings through generalized transduction. Conclusions: Our results showed a remarkable occurrence of ESBL genes in bacteriophage and bacterial population of effluent discharge, which clearly indicates that bacteriophages are an important factor in ESBL genes exchange among bacterial population through generalized transduction.

Studies on molecular epidemiology of ESβL-producing Klebsiella pneumoniae isolated from patients hospitalized in a specialist hospital in southern Poland

Introduction. Extended-spectrum β-lactamase (ESβL)-producing Klebsiella pneumoniae is currently one of the most common causes of nosocomial infections worldwide. The study aimed to characterize antibiotic resistance profile, the prevalence of selected genes encoding ESβLs, virulence, and the genetic relationship in 139 K. pneumoniae isolates identified in John Paul II Specialist Hospital in Southern Poland, collected in 2016.

Materials/Methods. Bacterial identification and the preliminary antibiotic susceptibilities was performed using the VI-TEK® 2 Compact automated system. Genes encoding ESβLs were amplified by CTX-Mplex PCR and PCR reactions. The presence of nine genes encoding virulence factors was studied by multiplex PCR. Clonality was investigated by PFGE after digestion with SpeI endonuclease.

Results. K. pneumoniae were mostly recovered from the respiratory tract (40.3%), urine (32.4%), wound swabs (19.4%) and blood (5%). In summary, 82.7% of strains were classified as multidrug resistant (MDR). All isolates were confirmed as ESβL producers and carried bla CTX-M-type (85.6%), bla SHV (82%), bla TEM (77.7%), bla CTX-M-9 (75.6%) and bla CTX-M-1 (1.4%) in various combinations. Moreover, triple bla genes were observed in 72% of isolates. The most common virulence-as-sociated genes found among the isolates were entB (91.4%), ybtS (55.4%), iutA (55.4%), magA (53.2%), kfu (14.4%), K2 (11.5%), mrkD (10.1%), rmpA (7.9%) and allS (5%). The PFGE analysis identified 4 major clusters (A–D) comprising 61% of the entire collection.

Conclusions. Our results indicate that the presence of a wide variety of MDR K. pneumoniae harbor ESβLs and virulence genes. Studies on molecular epidemiology of ESβL-producing K. pneumoniae isolates are needed, particularly for epidemiological surveillance in the hospital environment.

Biofilm Formation of Clinical Klebsiella pneumoniae Strains Isolated from Tracheostomy Tubes and Their Association with Antimicrobial Resistance, Virulence and Genetic Diversity

(1) Background: Due to the commonness of tracheotomy procedures and the wide use of biomaterials in the form of tracheostomy tubes (TTs), the problem of biomaterial-associated infections (BAIs) is growing. Bacterial colonization of TTs results in the development of biofilms on the surface of biomaterials, which may contribute to the development of invasive infections in tracheostomized patients. (2) Methods: Clinical strains of K. pneumoniae, isolated from TTs, were characterized according to their ability to form biofilms, as well as their resistance to antibiotics, whether they harbored ESβL genes, the presence of selected virulence factors and genetic diversity. (3) Results: From 53 patients, K. pneumoniae were detected in 18 of the TTs examined, which constituted 34% of all analyzed biomaterials. Three of the strains (11%) were ESβL producers and all had genes encoding CTX-M-1, SHV and TEM enzymes. 44.4% of isolates were biofilm formers, SEM demonstrating that K. pneumoniae formed differential biofilms on the surface of polyethylene (PE) and polyvinyl chloride (PVC) TTs in vitro. A large range of variation in the share of fimbrial genes was observed. PFGE revealed sixteen genetically distinct profiles. (4) Conclusions: Proven susceptibility of TT biomaterials to colonization by K. pneumoniae means that the attention of research groups should be focused on achieving a better understanding of the bacterial pathogens that form biofilms on the surfaces of TTs. In addition, research efforts should be directed at the development of new biomaterials or the modification of existing materials, in order to prevent bacterial adhesion to their surfaces.

The role of medical equipment in the spread of nosocomial infections: a cross-sectional study in four tertiary public health facilities in Uganda

Background

With many medical equipment in hospitals coming in direct contact with healthcare workers, patients, technicians, cleaners and sometimes care givers, it is important to pay close attention to their capacity in harboring potentially harmful pathogens. The goal of this study was to assess the role that medical equipment may potentially play in hospital acquired infections in four public health facilities in Uganda.

Methods

A cross-sectional study was conducted from December 2017 to January 2018 in four public health facilities in Uganda. Each piece of equipment from the neonatal department, imaging department or operating theatre were swabbed at three distinct points: a location in contact with the patient, a location in contact with the user, and a remote location unlikely to be contacted by either the patient or the user. The swabs were analyzed for bacterial growth using standard microbiological methods. Seventeen bacterial isolates were randomly selected and tested for susceptibility/resistance to common antibiotics. The data collected analyzed in STATA version 14.

Results

A total of 192 locations on 65 equipment were swabbed, with 60.4% of these locations testing positive (116/192). Nearly nine of ten equipment (57/65) tested positive for contamination in at least one location, and two out of three equipment (67.7%) tested positive in two or more locations. Of the 116 contaminated locations 52.6% were positive for Bacillus Species, 14.7% were positive for coagulase negative staphylococcus, 12.9% (15/116) were positive for E. coli, while all other bacterial species had a pooled prevalence of 19.8%. Interestingly, 55% of the remote locations were contaminated compared to 66% of the user contacted locations and 60% of the patient contacted locations. Further, 5/17 samples were resistant to at least three of the classes of antibiotics tested including penicillin, glycylcycline, tetracycline, trimethoprim sulfamethoxazole and urinary anti-infectives.

Conclusion

These results provides strong support for strengthening overall disinfection/sterilization practices around medical equipment use in public health facilities in Uganda. There’s also need for further research to make a direct link to the bacterial isolates identified and cases of infections recorded among patients in similar settings.

Prevalence of Extended-Spectrum β-lactamase and Integron Gene Carriage in Multidrug-Resistant Klebsiella Species Isolated from Outpatients in Yazd, Iran

Background:

Community-acquired infections by multidrug-resistant (MDR), extended-spectrum β-lactamase (ESBL) producing Klebsiella species (Klebsiella spp.) is of major concern worldwide. Antibiotic resistance, production of extended-spectrum β-lactamases (ESBLs), and carbapenemases, as well as the presence of classes 1, 2, and 3 integrons in outpatient isolates of Klebsiella collected from Yazd central laboratory, Yazd, Iran

Methods:

We collected 250 Klebsiella isolates from Yazd central laboratory between August 2015 and October 2017. Antibiotic susceptibility was determined against 18 antibiotics by disc diffusion, and multidrug-resistant isolates were tested for ESBL production by the phenotypic confirmatory test according to CLSI 2017 protocols. The amplification of β-lactamase genes bla_SHV, bla_TEM, bla_CTX-M, bla_OXA-48, bla_KPC, and bla_NDM, classes 1, 2, and 3 integrase genes, was carried out using specific primers and polymerase chain reaction (PCR)

Results:

Of the 250 Klebsiella outpatient isolates, 3.6% were K. oxytoca and the rest were K. pneumoniae. Disc diffusion showed that 21 (8.4%) isolates were MDR, 19 (90.4%) of which were ESBL producers including one K. oxytoca. The most prevalent β-lactamase gene was bla_SHV followed by bla_TEM and bla_CTX-M, but bla_OXA-48, bla_KPC, and bla_NDM were not detected. Class 1 integron was detected in 18 out of 21 MDR isolates (85.7%), but classes 2 and 3 were not observed. Two isolates were resistant to carbapenems and harbored bla_SHV, bla_TEM, and bla_CTX-M, as well as class 1 integron.

Conclusion:

ESBL production and the presence of multiple β-lactamase genes in MDR community isolates of Klebsiella spp. can have significant implications in terms of the spread of these opportunistic pathogens.

DNA Sequence Analysis of BlaVEB Gene Encoding Multi-drug Resistant and Extended-spectrum β-lactamases Producer Isolates of Enterobacteriaceae and Pseudomonas aeruginosa

Objective:

Multi-drug resistance Gram-negative bacteria possessing Extended-Spectrum β-Lactamase (ESBL) genes are of concern because of their resistance to third-generation cephalosporins. This study aims to investigate the molecular basis of resistance to modern β-lactams by ESBLs encoded by the blaVEB gene and the gene’s role in resistance. Also, gene sequencing was used to compare genetic similarities with global isolates using phylogenetic and cluster analyses.

Methods:

Between March and July 2018, a total of 100 Iraqi clinical isolates were examined, in this cross-sectional study, to determine their ESBL status using the double-disc synergy technique. Polymerase Chain Reactions (PCRs) were performed on extracted blaVEB genes and sequencing of the target PCR products was performed. All blaVEB sequences were compared with the available sequence data, using BLAST searches against the GenBank database.

Results:

A total of 35 isolates, comprising 5 Escherichia coli, 18 Klebsiella pneumoniae, and 12 Pseudomonas aeruginosa isolates were confirmed to possess ESBLs; the blaVEB gene was detected in one isolate of each species. The sequencing of these genes revealed 99% similarity with the global standard genes deposited in GenBank.

Conclusion:

The blaVEB gene plays an essential role in the resistance of ESBL-producing isolates to new β-lactams. Further, the sequencing and phylogenetic analyses of the genes from the P. aeruginosa, K. pneumonia, and E. coli isolates revealed 99% similarity with the GenBank global standard genes.

Prevalence of Extended-Spectrum β-Lactamases in Multi-drug Resistant Pseudomonas aeruginosa from Diabetic Foot Patients

INTRODUCTION

Pseudomonas aeruginosa is one of the major pathogens associated with the acute tissue damage in patients having Diabetic Foot Ulcer (DFU). The treatment of such infections can be an uphill battle due to the serious resistance to all the mainstay antibiotics, owing to overzealous production of Extended-Spectrum Beta-Lactamases (ESBLs). Pakistan also has a high prevalence of diabetes and complications related to it, however genetic disposition of the pathogens remains underinvestigated.

AIM

The main objective of the study was to determine the frequency of ESBLs in Multi-drug resistant P. aeruginosa from diabetic foot patients.

METHODS

The duration of the present study was one year and 100 patients having DFU were enrolled. All the pus samples were subjected to the bacterial culture, gram staining, catalase test, oxidase test and antimicrobial susceptibility pattern to various antibiotics for the confirmation of P. aeruginosa. Of 23 positive isolates of P. aeruginosa, 10 were ESBLs positive as detected by double disk diffusion test. The positive ESBL strain shows an increase of ≥5mm in the zone of inhibition of the combination discs in comparison to the alone ceftazidime disc.

RESULTS

The ESBLs positive strains were also tested for TEM-1, SHV-1, PER-1, and VEB-1, where: (07/10) strains carried SHV-1, (05/10) strains were positive for TEM-1, while none of the isolates were PCR-positive for PER-1 and VEB-1.

CONCLUSION

The findings of the current study show a difference in the pattern of ESBL genes compared to that of other such endeavors. The present study also warrants the PCR-based detection of the type of ESBL as a potential factor to consider in deciding the therapeutic strategy at any point during the treatment.

Frequency and molecular epidemiology of class A ESBLs producing Enteroinvasive Escherichia coli (EIEC) isolates among patients with diarrhea

AIM

This study aimed to investigate the frequency and molecular epidemiology of class A ESBLs producing Enteroinvasive Escherichia coli (EIEC) isolates among patients with diarrhea.

BACKGROUND

Antibiotic resistance is widespread among diarrheagenic Escherichia coli (DEC) in developing countries. Information regarding Extended-Spectrum β-Lactamases (ESBLs) in diarrheagenic pathogens should be considered in clinical management when an optimal treatment is required.

METHODS

A total of 581 stool samples were collected from patients with diarrhea in Ahvaz, Iran. PCR was used for the presence of the ipaH gene to confirm EIEC strains. The antibiotic resistance pattern of all EIEC isolates was determined by the disk diffusion method. EIEC isolates were screened for class A β-lactamase genes. Genotyping of harboring β-lactamase genes was performed by Multi-Locus VNTR Analysis (MLVA).

RESULTS

Among 13 EIEC isolates, 9 isolates (69.2%) were found ESBL positive by double-disk synergy test (DDST) and PCR. Furthermore, bla _CTX-M-15 and bla _CTX-M-1 genes were detected in 77.8% (n=7) and 44.5% (n=4) of the bla _CTX-M-1 group. On the other hand, the bla _TEM-1 gene was detected in 66.6% (n=6). None of the isolates had bla _SHV-1, bla _KPC, or bla _GES genes. Six MLVA genotypes were identified.

CONCLUSION

The current study revealed that the presence of ESBLs genes mediates the resistance of EIEC isolates to the majority of antibiotics in this region. The presence of ESBLs genes in different MLVA types showed that one specific clone was not responsible for spreading the EIEC isolates.

Molecular detection and antibiotic resistance pattern of extended-spectrum beta-lactamase producing Escherichia coli in a Tertiary Hospital in Enugu, Nigeria

BACKGROUND

The use of antibiotic agents in the treatment of infectious diseases has greatly contributed to the decrease in morbidity and mortality, but these great advances in treatment are being undermined by the rapidly increasing antimicrobial resistant organisms. Extended-spectrum beta-lactamases are enzymes hydrolyzing the beta lactam antibiotics, including third generation cephalosporins and monobactams but not cephamycins and carbapenems. They pose a serious global health threat and have become a challenge for health care providers. The aim of this research was to assess the prevalence of extended-spectrum beta-lactamase producing Escherichia coli in University of Nigeria Teaching Hospital Ituku-Ozalla Enugu and to detect the risk factors for acquisition of the resistant organism. To proffer advice on antibiotic stewardship in clinical practice and public health interventions, to curb the spread of the resistant organisms in the hospital.

RESULTS

Out of the 200 E. coli isolates, 70 (35.00%) were confirmed positive for extended-spectrum beta-lactamase production. Fifty-three (75.7%) were from hospital acquired infections. All the isolates were resistant to ampicillin, tetracycline and chloramphenicol while 68 (97.14%) of the 70 isolates were susceptible to imipenem. BlaTEM, blaSHV and blaTEM were detected in 66 (94%) of the 70 isolates. The ESBL bla genes detected were blaCTX-M (n = 26; 37.14%), blaTEM (n = 7; 10.00%), blaSHV (n = 2; 2.86%), blaCTX-M/TEM (n = 7; 10.0%), blaCTX-M/SHV (n = 14; 20.0%) and blaCTX-M/TEM/SHV (n = 10; 14.29%). The three bla genes were not detected in 4 (5.71%) of the isolates. Recent surgery, previous antibiotic and intensive care unit admission were the associated risk factors to infections caused by extended-spectrum beta-lactamase producing E. coli.

CONCLUSION

There is a high rate of infections caused by extended-spectrum beta-lactamase producing E. coli. Recent surgery, previous antibiotic and intensive care unit admission were associated risk factors.

Synergistic evaluation of AgO2 nanoparticles with ceftriaxone against CTXM and blaSHV genes positive ESBL producing clinical strains of Uro-pathogenic E. coli

The silver oxide nanoparticles (AgO₂-NPs) were synthesised using silver foil as a new precursor in wet chemical method. X-ray diffraction analysis shows crystallographic structures of AgO₂-NPs with crystallite size of 35.54 nm well-matched with standard cubic structure. Scanning electron microscopy analysis clearly shows the random distribution of spherical-shaped nanoparticles. Energy dispersive X-ray analysis confirmed the purity of the samples as it shows no impurity element. Fourier transforms infra-red analysis confirmed the formation of AgO₂-NPs with the presence of Ag-O-Ag stretching bond. All the techniques also confirmed the loading of ceftriaxone drug on the surface of AgO₂-NPs. This study also described the effect of AgO₂-NPs having synergistic activity with β lactam antibiotic i.e. ceftriaxone against ESBL generating Escherichia coli (E. coli). Among isolated strains of E. coli, 60.0% were found to be ESBL producer. The synergistic activities of AgO₂-NPs with ceftriaxone suggest that these combinations are effective against MDR-ESBL E. coli strains as evident by increase in zone sizes. The present study observed rise in MDR-ESBL E. coli with polymorphism of blaCTXM and blaSHV causing UTI infections in Pakistani population. The antibiotic and AgO₂-NPs synergistic effect can be used as an efficient approach to combat uro-pathogenic infections.

Preliminary survey of extended-spectrum β-lactamases (ESBLs) in nosocomial uropathogen Klebsiella pneumoniae in north-central Iran

Infections caused by extended-spectrum β-lactamases (ESBLs) producing bacteria, including Klebsiella pneumoniae have increasingly subjected to therapeutic limitations and patients with these infections are at high risk for treatment failure, long hospital stays, high health care costs, and high mortality. The aim of this study was to screen the prevalence of the bla_TEM,bla_CTX-M and bla_SHV ESBL genes in K. pneumoniae strains isolated from nosocomial urinary tract infections (UTIs). During the March 2016 to December 2017, one hundred isolates of K. pneumoniae were collected from urine specimens of patients suffering from nosocomial UTI referred to Khatam Al-Anbia hospital in Shahrud, north-central Iran. All isolates were identified by standard bacteriological tests. The pattern of antibiotic susceptibility was determined according to the CLSI guidelines. The presence of the ESBLs was investigated using the double-disc synergy test (DDST). Polymerase chain reaction technique was used to detect the bla_TEM, bla_CTX-M and bla_SHV genes in DDST positive isolates. Most isolates showed remarkable resistance to tested antibiotics with highest rate against nitrofurantoin (75%) and trimethoprim/sulfamethoxazole (65%). The imipenem was the most effective antibiotic against K. pneumoniae isolates. ESBL phenotype was detected in 50 (50%) of isolates. The prevalence of bla_TEM, bla_CTX-M and bla_SHV genes among 50 ESBLs-positive isolates was 25 (50%), 15 (30%) and 35 (70%) respectively. The bla_TEM and bla_SHV genes were seen in 25 isolates (50%) simultaneously. The findings of this study indicated the 50% frequency rate of ESBL-producing K. pneumoniae in our geographic region. Since the treatment of infections caused by this bacterium is associated with many limitations, this high prevalence is a warning sign to adopt new control policies to prevent further spread of this microorganism.

An Outbreak of ESBL-producing Klebsiella pneumoniae in an Iranian Referral Hospital: Epidemiology and Molecular Typing

INTRODUCTION

Klebsiella pneumoniae is a common cause of nosocomial infections; however, there is limited information in Iran regarding nosocomial outbreaks due to extended-spectrum β-lactamase (ESBL) producing K pneumoniae strains, particularly using molecular methods. The present study focused on the molecular mechanism of ESBL resistance and genetic relatedness in K. pneumoniae isolates causing nosocomial infections in an Iranian referral hospital.

MATERIAL AND METHODS

This study evaluated the antimicrobial resistance and molecular epidemiology of K. pneumoniae causing nosocomial infections in children between October 2013 and March 2014. The ESBL detection was carried out for all the isolates by the CLSI method and PCR was carried out for the detection of the blaSHV, blaTEM, and blaCTX-M genes among ESBL-producing K. pneumonia. Molecular typing of the K. pneumoniae was performed using random amplification of polymorphic DNA-polymerase chain reaction (RAPD-PCR).

RESULTS

A total of 30 isolates of K. pneumoniae were used for epidemiological analysis. High rates of resistance to cefotaxime (n=29, 97%), cefazolin (n=29, 97%), cefepime (n=25, 83%) and gentamicin (n=23, 77%) were observed. A total of 29 strains (97%) produced ESBLs. The frequency of blaSHV, blaCTX-M and blaTEM genes among these isolates was 83% (n=25), 70% (n=21) and 57% (n=17), respectively. Surprisingly 11 isolated (37%) carried blaSHV, blaCTX-M and blaTEM genes simultaneously. Moreover, the concurrent presence of "blaSHV and blaCTX-M" and "blaSHV and blaTEM" was seen in 8 (27%) and 4 (13%) isolates, respectively. RAPDPCR analyses revealed that K. pneumoniae isolates belonged to 2 RAPD-PCR types among which one cluster counted for 28 isolates.

CONCLUSION

To our knowledge, this is the first published report of a nosocomial outbreak of ESBL-producing K. pneumoniae in children in Iran. Although the epidemiology of nosocomial infections with ESBL-producing organisms has not yet been explored in depth in Iran, our findings suggest that ESBL-producing organisms are already an established public health threat in our country.

Prevalence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae: First systematic review and meta-analysis from Iran

OBJECTIVES

Extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) have emerged as an important pathogen causing severe infections worldwide. Infections due to ESBL-KP are associated with high morbidity and mortality, especially in developing countries such as Iran. The aim of this study was to assess the pooled prevalence of ESBL-KP with different gene variants in Iran.

METHODS

A literature search of Medline (via PubMed), Embase, Web of Science and Iranian Database was performed. A meta-analysis was conducted using Comprehensive Meta-Analysis Software (version 2.2, Biostat). A fixed- or random-effects model was used based on the heterogeneity test. Publication bias was determined using Begg's rank correlation and Egger's weighted regression methods.

RESULTS

Among 783 articles identified, 43 studies met the eligibility criteria. The pooled prevalence of ESBL-KP was 43.5% (95% CI 39.3-47.9%) among clinical K. pneumoniae isolates. Among genes encoding ESBLs during 2000-2009, SHV, CTX-M and TEM were found with prevalences of 23.3%, 15.2% and 12.3%, respectively, whilst the prevalences of SHV, CTX-M, TEM and VEB were 24%, 28.1%, 25.2% and 8.3%, respectively, during the period 2010-2018.

CONCLUSION

The prevalence of ESBL-KP has increased steadily in recent years among clinical K. pneumoniae isolates in Iran. Thus, initial identification of ESBL-KP according to Clinical and Laboratory Standards Institute (CLSI) guidelines, proper molecular approaches, and implementation of antimicrobial stewardship programmes in Iranian hospitals together with comprehensive infection control measures are urgently needed to control the dissemination of these strains.

Incidence and molecular characterization of the extended spectrum beta lactamase-producing Escherichia coli isolated from urinary tract infections in Eastern Saudi Arabia

Objectives:

To find the prevalence of uropathogenic Escherichia coli (E. coli)-producing extended spectrum beta lactamase (ESBL) at King Fahd Military Medical Complex in Dhahran (KFMMC) and to detect the genes responsible for its production. In addition, we determined the pattern of multi-drug resistance among isolates.

Methods:

A total of 117 uropathogenic E. coli isolates were collected from KFMMC over a period of 4 months from March 2014 to June 2014. These were received in the Microbiology Laboratory at Prince Sultan Military College of Health Sciences (PSMCHS), Dhahran, Saudi Arabia for analysis. The isolates were screened for ESBL using VITEK^® 2 Compact. Polymerase chain reaction (PCR) examination was used to determine TEM, SHV, and CTX-M genes.

Results:

Our findings indicated that there is a high incidence of ESBLs among the E. coli isolated from UTI (23.1%). Our study also indicated that CTX-M genes are the most prevalent among the isolates at KFMMC followed by TEM class (6%), but there was also a higher percentage E. coli (3.4%) simultaneously harboring TEM and CTX-M genes. None of our isolates harbored the SHV genes.

Conclusion:

The findings document the threat of ESBL among E. coli isolates from UTI especially the CTX-M class in our hospital with the occurrence of these strains as etiologic agents of infection in the hospital and community.

Ambulance vehicles as a source of multidrug-resistant infections: a multicenter study in Assiut City, Egypt

Background

Ambulances may represent a potential source of infection to patients, patients’ relatives, and paramedical staffs. In this study, we analyzed the extent of bacterial contamination in ambulance vehicles and measured the degree of antimicrobial resistance among isolated pathogens.

Materials and methods

Twenty-five vehicles were included and 16 sampling points were swabbed in each vehicle. Then the swabs were immediately transferred to the laboratory to identify bacterial contaminants utilizing standard microbiological procedures and API^® systems. Antibiotic susceptibility testing and screening for methicillin-resistant staphylococci and extended spectrum β-lactamases (ESBLs)-producing Gram-negative rods were carried out.

Results

A total of 400 samples were collected, 589 bacteria were isolated and 286 (48.6%) of the isolates were potentially pathogenic. The highest contamination rate with pathogenic bacteria was detected in suction devices (75.8%) and stethoscopes (67.7%). Staphylococci were the most frequently detected microorganisms (n=184) followed by Klebsiella spp. (49), Escherichia coli (40), Citrobacter spp. (7), and Proteus spp. (6). Staphylococci were mostly sensitive to vancomycin, whereas Gram-negative bacteria were sensitive to imipenem. Overall, 46.1% of Staphylococcus aureus were methicillin resistant, whereas 20.4% of the coagulase-negative staphylococci were methicillin resistant. Moreover, 36.7% of Klebsiella spp. and 27.5% of E. coli were ESBL producers.

Conclusion

Our study provides evidence that ambulances represent a source of prehospital multidrug-resistant infections.

Detection of CTX-M-15 beta-lactamases in Enterobacteriaceae causing hospital- and community-acquired urinary tract infections as early as 2004, in Dar es Salaam, Tanzania

Background

The spread of Extended Spectrum β-lactamases (ESBLs) among Enterobacteriaceae and other Gram-Negative pathogens in the community and hospitals represents a major challenge to combat infections. We conducted a study to assess the prevalence and genetic makeup of ESBL-type resistance in bacterial isolates causing community- and hospital-acquired urinary tract infections.

Methods

A total of 172 isolates of Enterobacteriaceae were collected in Dar es Salaam, Tanzania, from patients who met criteria of community and hospital-acquired urinary tract infections. We used E-test ESBL strips to test for ESBL-phenotype and PCR and sequencing for detection of ESBL genes.

Results

Overall 23.8% (41/172) of all isolates were ESBL-producers. ESBL-producers were more frequently isolated from hospital-acquired infections (32%, 27/84 than from community-acquired infections (16%, 14/88, p < 0.05). ESBL-producers showed high rate of resistance to ciprofloxacin (85.5%), doxycycline (90.2%), gentamicin (80.5%), nalidixic acid (84.5%), and trimethoprim-sulfamethoxazole (85.4%). Furthermore, 95% of ESBL-producers were multi-drug resistant compared to 69% of non-ESBL-producers (p < 0.05). The distribution of ESBL genes were as follows: 29/32 (90.6%) bla_CTX-M-15, two bla_SHV-12, and one had both bla_CTX-M-15 and bla_SHV-12. Of 29 isolates carrying bla_CTX-M-15, 69% (20/29) and 31% (9/29) were hospital and community, respectively. Bla_SHV-12 genotypes were only detected in hospital-acquired infections.

Conclusion

bla_CTX-M-15 is a predominant gene conferring ESBL-production in Enterobacteriaceae causing both hospital- and community-acquired infections in Tanzania.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2395-8) contains supplementary material, which is available to authorized users.

Assessment of antibiotic resistance in Klebsiella pneumoniae exposed to sequential in vitro antibiotic treatments

BACKGROUND

Bacteria treated with different classes of antibiotics exhibit changes in susceptibility to successive antibiotic treatments. This study was designed to evaluate the influence of sequential antibiotic treatments on the development of antibiotic resistance in Klebsiella pneumoniae associated with β-lactamase and efflux pump activities.

METHODS

The antibiotic susceptibility, β-lactamase activity, and efflux activity were determined in K. pneumoniae grown at 37 °C by adding initial (0 h) and second antibiotics (8 or 12 h). Treatments include control (CON; no first and second antibiotic addition), no initial antibiotic addition followed by 1 MIC ciprofloxacin addition (CON-CIP), no initial antibiotic addition followed by 1 MIC meropenem addition (CON-MER), initial 1/4 MIC ciprofloxacin addition followed by no antibiotic addition (1/4CIP-CON), initial 1/4 MIC ciprofloxacin addition followed by 1 MIC ciprofloxacin addition (1/4CIP-CIP), and initial 1/4 MIC ciprofloxacin addition followed by 1 MIC meropenem addition (1/4CIP-MER).

RESULTS

Compared to the CON, the initial addition of 1/4 MIC ciprofloxacin inhibited the growth of K. pneumoniae throughout the incubation period. The ciprofloxacin treatments (CON-CIP and 1/4CIP-CIP) showed significant reduction in the number of K. pneumoniae cells compared to meropenem (CON-MER and 1/4CIP-MER). The 1/4CIP-CIP achieved a further 1 log reduction of K. pneumoniae, when compared to the 1/4CIP-CON and 1/CIP-MER. The increase in sensitivity of K. pneumoniae to cefotaxime, kanamycin, levofloxacin, nalidixic acid was observed for CON-CIP. Noticeable cross-resistance pattern was observed at the 1/4CIP-CIP, showing the increased resistance of K. pneumoniae to chloramphenicol, ciprofloxacin, kanamycin, levofloxacin, nalidixic acid norfloxacin, sulphamethoxazole/trimethoprim, and tetracycline. The levels of β-lactamase activities were estimated to be 8.4 μmol/min/ml for CON, 7.7 μmol/min/ml for 1/4CIP-CON and as low as 2.9 μmol/min/ml for CON-CIP. Compared to the absence of phenylalanine-arginine-β-naphthylamide (PAβN), the fluorescence intensity of EtBr was increased in K. pneumoniae cells treated at the CON, CON-CIP, and CON-MER in the presence of PAβN. However, the efflux pump activity remained in K. pneumoniae cells treated at the 1/CIP, 1/CIP-CIP, and 1/CIP-MER in the presence of PAβN.

CONCLUSION

The results suggest that the pre-exposed antibiotic history, treatment order, and concentrations influenced the development of multiple antibiotic resistant associated with β-lactamase and efflux pump activities. This study highlights the importance of antibiotic treatment conditions, which would be taken into consideration when new antibiotic strategy is designed to prevent antibiotic resistance.

Distribution of virulence genes and genotyping of CTX-M-15-producing Klebsiella pneumoniae isolated from patients with community-acquired urinary tract infection (CA-UTI)

Klebsiella pneumoniae is one of the most important agents of community-acquired urinary tract infection (CA-UTI). In addition to extended-spectrum β-lactamases (ESBLs), a number of virulence factors have been shown to play an important role in the pathogenesis of K. pneumoniae, including capsule, siderophores, and adhesins. Little is known about the genetic diversity and virulence content of the CTX-M-15-producing K. pneumoniae isolated from CA-UTI in Iran. A total of 152 K. pneumoniae isolates were collected from CA-UTI patients in Tehran from September 2015 through April 2016. Out of 152 isolates, 40 (26.3%) carried bla_CTX-M-15. PCR was performed for detection of virulence genes in CTX-M-15-producing isolates. Furthermore, all of these isolates were subjected to multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA). Using MLVA method, 36 types were identified. CTX-M-15-producing K. pneumoniae isolates were grouped into 5 clonal complexes (CCs). Of these isolates, mrkD was the most prevalent virulence gene (95%), followed by kpn (60%), rmpA (37.5%), irp (35%), and magA (2.5%). No correlation between MLVA types or CCs and virulence genes or antibiotic resistance patterns was observed. Overall, it is thought that CTX-M-15-producing K. pneumoniae strains isolated from CA-UTI have arisen from different clones.