Antimicrobial Resistance Patterns and Prevalence of blaPER-1 and blaVEB-1 Genes Among ESBL-producing Pseudomonas aeruginosa Isolates in West of Iran

Distribution of blaOXA-10, blaPER-1, and blaSHV genes in ESBL-producing Pseudomonas aeruginosa strains isolated from burn patients

Pseudomonas aeruginosa is resistant to a wide range of extended spectrum-lactamases (ESBLs) antibiotics because it produces several kinds of ESBLs. The goal of the current investigation was to identify the bacteria that produce extended spectrum -lactamases and the genes that encode three different ESBLs, such as blaOXA-10, blaPER-1 and blaSHV genes in Pseudomonas aeruginosa isolated from burn patients. In this investigation, 71 Pseudomonas aeruginosa isolates were isolated from burn wounds in Burn and Plastic Surgery Hospital, Duhok City between July 2021 to June 2022. For the purpose of finding the blaOXA-10, blaPER-1, and blaSHV ESBL expressing genes, Polymerase Chain Reaction (PCR) was used. Among 71 Pseudomonas aeruginosa isolates, 26.36% (29/71) were isolated from males and 38.18% (42/71) from females, and 76.06% (54/71) of the isolates were multidrug resistant. They exhibited higher resistance against Piperacillin with resistance rates of 98.59%. Among the ESBL-producing isolates tested, blaOXA-10 was found in 59.26% (32), blaPER-1 was found in 44.44% (24), and blaSHV was found in 11.11% (6). All isolates must undergo antimicrobial susceptibility testing because only a few numbers of the available antibiotics are effective for the treatment of this bacterium. This will prevent the development of resistance in burn units and aids in the management of the treatment plan.

Detection of Virulence Factors and Antibiotic Resistance among Klebsiella pneumoniae Isolates from Iran

The current study assessed the detection of virulence genes and drug resistance among Klebsiella pneumoniae isolates from Iran. During 2018 to 2020, 52 K. pneumoniae isolates were obtained from patients at Iran hospitals. By disk diffusion method, the antimicrobial susceptibility of K. pneumoniae isolates was assessed, and ESBL-producing K. pneumoniae isolates were detected by CDDT method. PCR analysis was done to detect virulence genes (iucB, iutA, iroN, kfu, allS, fimH, ybtS, mrkD, and entB); ESBL-encoding genes (bla TEM, bla PER, bla CTX-M, bla VEB, and bla SHV); and class D (bla OXA-48), class B (bla VIM, bla NDM, and bla IMP), and class A (bla KPC and bla GES) carbapenemase genes. Among all isolates, 84.6%, 13.5%, and 1.9% isolates were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. Also, 84.6% were ESBL-producing and 71.2%, 53.8%, 40.4%, and 9.6% of all isolates were carrying bla TEM, bla SHV, bla CTX-M, and bla OXA-48 genes, respectively. Six isolates (11.5%) were positive for bla NDM gene. In contrast, no isolates were positive for the presence of bla KPC, bla IMP, and bla VIM. Virulence factor genes including iucB, iutA, iroN, kfu, allS, fimH, ybtS, mrkD, and entB were carried by 24%, 46.2%, 25%, 11.5%, 17.3%, 86.5%, 75%, 88.5%, and 100% isolates, respectively. This study evaluated the distribution and prevalence of virulence factor genes among K. pneumoniae isolates. The treatment of these infections is challenging due to the existence of particular virulence factors and the rise of antibiotic resistance. Therefore, the current study accentuates the necessity of finding new and efficient solutions for stopping the increase of antibiotic resistance.

Detection of extensively drug-resistant and hypervirulent Klebsiella pneumoniae ST15, ST147, ST377 and ST442 in Iran

In this study, we focused on the emergence of extensively drug-resistant (XDR), pandrug-resistant (PDR), and hypervirulent Klebsiella pneumoniae (hvKP) in Iran. During 2018 to 2020 a total of 52 K. pneumoniae isolates were collected from different clinical specimens. The hvKP isolates were identified by PCR amplification of virulence and capsular serotype-specific genes. Hypermucoviscous K. pneumoniae (hmKP) were identified by string test. Carbapenem-resistant hvKP (CR-hvKP), multidrug-resistant hvKP (MDR-hvKP), extensively drug-resistant hvKP (XDR-hvKP), and pandrug-resistant hvKP (PDR-hvKP) were determined by disc diffusion method, Carba-NP test and PCR method. XDR-hvKP isolates were typed by multilocus sequence typing (MLST). Among all K. pneumoniae isolates 14 (26.9%) were identified as hvKP and 78.6% (11/14) of them were hmKP however, none of the classic K. pneumoniae (cKP) isolates were hmKP. The predominant capsular serotype of hvKP was K2 (42.85%) followed by K1 (35.71%). The prevalence of MDR-hvKP, XDR-hvKP and PDR-hvKP isolates were 6 (42.9%), 5 (35.7%) and 1 (7.1%), respectively. ESBL production was found in 85.7% of hvKP isolates and most of them carried bla TEM gene (78.6%) and 6 isolates (42.9%) were CR-hvKP. Among hvKP isolates, 1 (7.1%), 2 (14.3%), 3 (21.4%), 8 (28.6%), and 11 (78.6%) carried bla NDM-6, bla OXA-48, bla CTX-M, bla SHV, and bla TEM genes, respectively. According to MLST analysis, 2, 1, 1, and 1 XDR-hvKP isolates belonged to ST15, ST377, ST442, and ST147, respectively. The occurrence of such isolates is deeply concerning due to the combination of hypervirulence and extensively drug-resistance or pandrug-resistance.

The impact of infectious diseases consultation on the management and outcomes of Pseudomonas aeruginosa bacteraemia in adults: a retrospective cohort study

BACKGROUND

Pseudomonas aeruginosa bacteraemia (PAB) is associated with high mortality. The benefits of infectious diseases consultation (IDC) has been demonstrated in Staphylococcal aureus bacteraemia and other complex infections. Impact of IDC in PAB is unclear. This study aimed to evaluate the impact of IDC on the management and outcomes in patients with PAB.

METHODS

This is a retrospective cohort single-centre study from 1 November 2006 to 29 May 2019, in all adult patients admitted with first episode of PAB. Data collected included demographics, clinical management and outcomes for PAB and whether IDC occurred. In addition, 29 Pseudomonas aeruginosa (PA) stored isolates were available for Illumina whole genome sequencing to investigate if pathogen factors contributed to the mortality.

RESULTS

A total of 128 cases of PAB were identified, 71% received IDC. Patients who received IDC were less likely to receive inappropriate duration of antibiotic therapy (4.4%; vs 67.6%; p < 0.01), more likely to be de-escalated to oral antibiotic in a timely manner (87.9% vs 40.5%; p < 0.01), undergo removal of infected catheter (27.5% vs 13.5%; p = 0.049) and undergo surgical intervention (20.9% vs 5.4%, p = 0.023) for source control. The overall 30-day all-cause mortality rate was 24.2% and was significantly higher in the no IDC group in both unadjusted (56.8% vs 11.0%, odds ratio [OR] = 10.63, p < 0.001) and adjusted analysis (adjusted OR = 7.84; 95% confidence interval, 2.95-20.86). The genotypic analysis did not reveal any PA genetic features associated with increased mortality between IDC versus no IDC groups.

CONCLUSION

Patients who received IDC for PAB had lower 30-day mortality, better source control and management was more compliant with guidelines. Further prospective studies are necessary to determine if these results can be validated in other settings.

Emergence and Expansion of a Carbapenem-Resistant Pseudomonas aeruginosa Clone Are Associated with Plasmid-Borne bla KPC-2 and Virulence-Related Genes

Pseudomonas aeruginosa is a major opportunistic pathogen and one of the leading bacterial species causing health care-associated infections. Carbapenems are the most effective antimicrobial agents for the treatment of severe infections caused by P. aeruginosa However, our recent surveillance demonstrated that the prevalence of carbapenem-resistant P. aeruginosa (CRPA) reached 38.67% in Zhejiang, China. By analyzing CRPA isolates collected from patients from 2006 to 2018, we found that 33% of CRPA isolates carried the gene bla _KPC-2, which conferred high-level resistance to carbapenems and other β-lactams. In particular, a CRPA clone, ST463 (sequence type 463), emerged and has become the predominant CRPA clone among the population. Genome sequencing demonstrated that ST463 expansion was associated with plasmid-borne bla _KPC-2 The mobile element flanking bla _KPC-2, the type IV secretion system, and the successful expansion of clone ST463 might have further favored bla _KPC-2 spread in P. aeruginosa Molecular clock analysis dated the emergence of clone ST463 to around 2007. Genome-wide association analysis showed that 567 genes were associated with clone ST463, including several known virulence genes related to the biosynthesis of lipooligosaccharide (LOS) O-antigens and exotoxin. These findings indicate that ST463 is expanding with plasmid-borne bla _KPC-2 and virulence-related genes in nosocomial infections, and close surveillance should be undertaken in the future.IMPORTANCE Health care-associated infections, also known as nosocomial infections, are the most frequent adverse events in health care delivery worldwide, causing high rates of morbidity and mortality and high health care costs. Pseudomonas aeruginosa is one of the leading bacterial species causing health care-associated infections. Carbapenems are the most effective antimicrobial agents for the treatment of its severe infections. However, the prevalence of carbapenem-resistant P. aeruginosa (CRPA) has been increasing rapidly in recent years, and our surveillance demonstrated that the prevalence of CRPA reached 38.67% in Zhejiang, China. Genome sequencing of CRPA isolates over a decade showed that a CRPA clone (ST463) emerged recently. The clone is highly resistant to β-lactams, including carbapenems, and fluoroquinolones. Genome-wide association analysis showed that the clone expanded with virulence-related genes and the plasmid-borne carbapenem-resistant gene bla _KPC-2 These findings are of significant public health importance, as the information will facilitate the control and minimization of CRPA nosocomial infections.

Sewage and sewage-contaminated environments are the most prominent sources to isolate phages against Pseudomonas aeruginosa

Background

P. aeruginosa is the primary source of hospital-acquired infections. Unfortunately, antibiotic resistance is growing to precariously high levels, making the infections by this pathogen life-threatening and hard to cure. One possible alternative to antibiotics is to use phages. However, the isolation of phages suitable for phage therapy— be lytic, be efficient, and have a broad host range —against some target bacteria has proven difficult. To identify the best places to look for these phages against P. aeruginosa we screened hospital sewages, soils, and rivers in two cities.

Results

We isolated eighteen different phages, determined their host range, infection property, and plaque morphology. We found that the sewage and sewage-contaminated environments are the most reliable sources for the isolation of Pseudomonas phages. In addition, phages isolated from hospital sewage showed the highest efficiency in lysing the bacteria used for host range determination. In contrast, phages from the river had larger plaque size and lysed bacteria with higher levels of antibiotic resistance.

Conclusions

Our findings provided additional support for the importance of sewage as the source of phage isolation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02197-z.

Antipseudomonal β-Lactams Resistance in Iran

Over the last years, the mortality rate of Pseudomonas aeruginosa, which is one of the major reasons for severe infections, has been significantly increasing. This bacterium is highly resistant to many antibiotics, especially carbapenems, thanks to its complicated mechanism by which it can acquire exogenous genes. The purpose of this research is to have a review of empirical studies surveying the P. aeruginosa resistance to beta-lactams in Iran in order to investigate the most reliable methods by which the incidence of P. aeruginosa infections can be decreased and controlled. We performed a systematic review of all articles published from 2008 until 2018. Studies which did not address P. aeruginosa resistance to beta-lactams were excluded from the analysis. Studies with less than 10 cases were also excluded. Studies with more than ten cases, which did not have repetitive information, were taken into account for the final selection; 133 out of 893 articles were chosen. The resistance rate of P. aeruginosa among the articles was as follows: more than 72% of studies revealed >50% level of resistance to cefepime, followed by aztreonam (53.2%), ceftazidime (61%), piperacillin/tazobactam (54.5%), meropenem (48.3%), and imipenem (42.4%). The selection of empiric antipseudomonal antibiotics is absolutely uncertain and hazardous, and the risk of clinical failure may be more among cephalosporins and piperacillin-tazobactam as well as aztreonam. The results of this study illustrate that the methods enabling clinics to identify the bacterium resistance pattern and its genetic basis and to have the opportunity of empiric therapies through access to updated local data of antimicrobial susceptibility pattern are the most effective methods. However, the widespread usage of these approaches undoubtedly needs reliable molecular and nucleic acid-based devices, which are both affordable and available.

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.

Understanding the Epidemiology of Multi-Drug Resistant Gram-Negative Bacilli in the Middle East Using a One Health Approach

In the last decade, extended-spectrum cephalosporin and carbapenem resistant Gram-negative bacilli (GNB) have been extensively reported in the literature as being disseminated in humans but also in animals and the environment. These resistant organisms often cause treatment challenges due to their wide spectrum of antibiotic resistance. With the emergence of colistin resistance in animals and its subsequent detection in humans, the situation has worsened. Several studies reported the transmission of resistant organisms from animals to humans. Studies from the middle east highlight the spread of resistant organisms in hospitals and to a lesser extent in livestock and the environment. In view of the recent socio-economical conflicts that these countries are facing in addition to the constant population mobilization; we attempt in this review to highlight the gaps of the prevalence of resistance, antibiotic consumption reports, infection control measures and other risk factors contributing in particular to the spread of resistance in these countries. In hospitals, carbapenemases producers appear to be dominant. In contrast, extended spectrum beta lactamases (ESBL) and colistin resistance are becoming a serious problem in animals. This is mainly due to the continuous use of colistin in veterinary medicine even though it is now abandoned in the human sphere. In the environment, despite the small number of reports, ESBL and carbapenemases producers were both detected. This highlights the importance of the latter as a bridge between humans and animals in the transmission chain. In this review, we note that in the majority of the Middle Eastern area, little is known about the level of antibiotic consumption especially in the community and animal farms. Furthermore, some countries are currently facing issues with immigrants, poverty and poor living conditions which has been imposed by the civil war crisis. This all greatly facilitates the dissemination of resistance in all environments. In the one health concept, this work re-emphasizes the need to have global intervention measures to avoid dissemination of antibiotic resistance in humans, animals and the environment in Middle Eastern countries.

Prevalence of extended-spectrum beta-lactamase genes in Acinetobacter baumannii strains isolated from nosocomial infections in Tehran, Iran

Background and objectives:bla_SHV, bla_TEM and bla_VEB are a group of Extended-Spectrum Beta-Lactamase enzymes (ESBLs) which are able to hydrolyze Penicillins and some cephalosporin antibiotics. The present study evaluated the frequency of ESBL genes bla_SHV, bla_TEM and bla_VEB in Acinetobacter baumannii strains isolated from nosocomial infections to outline the importance of these genes in antibiotic resistance.

Methods: One hundred Acinetobacter baumannii strains were isolated from different nosocomial infections. After antibiotic resistance evaluation with the Kirby-Bauer disc-diffusion method, the Minimum Inhibitory Concentration (MIC) of Ciprofloxacin was measured using the E-test method. Then, the ESBL producing strains were identified employing Combined Disk Methods. Finally, all isolates were evaluated with the Polymerase Chain Reaction (PCR) technique to detect the ESBL genes of interest.

Results: Out of 100 Acinetobacter baumannii isolates, 59% were ESBL positive according to the phenotypic method. The PCR assay could not detect the bla_SHV and bla_VEB genes in the studied isolates, but the presence of bla_TEM gene was demonstrated in 42% of the strains.

Conclusion: The high resistance to most antibiotics, the high prevalence of ESBLs-producing strains and also a high prevalence of bla_TEM gene in A. baumannii strains found in the current study gives cause for major concern about nosocomial infections in Iran because of the treatment complexity of these strains. Our results highlight the need for infection control measures to prevent the spread of resistant isolates, especially in hospitals.

Determination of virulence determinants of Escherichia coli strains isolated from patients with colorectal cancer compared to the healthy subjects

AIM

This study determined the genes encoding the binding and receiving factors of iron and microbial biofilm in E. coli strains isolated from mucosal samples of patients with colorectal cancer and inflammation of the colorectal compared to healthy people.

BACKGROUND

Colorectal cancer is one of the most important malignancies in recent years. Escherichia coli is the most important infectious agents associated with colorectal cancer that has numerous virulence factors such as iron uptake and adhesion factors included in the process of inflammation and colorectal cancer.

METHODS

Of the three healthy, inflammatory bowel diseases and colorectal cancer groups, 40 Escherichia coli strains isolated after confirmation by biochemical and molecular methods. After determining the isolates phylogroups, the frequency of genes was measured by PCR method. The biofilm formation of isolates was performed using Crystal Violet method.

RESULTS

In the determination of the bacteria phylogroups, the colorectal cancer isolates had a maximum incidence of phylogroups B2 and A. In the analysis of fimH, papA, papC, iutA, ireA and fyuA genes, the highest frequency was observed in these two phylogroups. The presence of ireA gene in bacterial isolates from three groups showed a significant difference (P value: 0.004). There was also no significant difference in biofilm productions in Escherichia coli strains isolated from the three groups.

CONCLUSION

Unlike previous studies focusing solely on Escherichia coli toxins, we found that iron absorption and adhesion factors could be effective in developing inflammatory bowel diseases and colorectal cancer. It was also determined that biofilm formation is a specific characteristic of Escherichia coli isolated from the healthy colon.

Molecular characterization of clinical and environmental Pseudomonas aeruginosa isolated in a burn center

In burn centers, Pseudomonas aeruginosa acts as a major cause of nosocomial infections. Therefore, this study aimed to characterize molecularly P. aeruginosa isolates collected from environmental samples and burn patients. A total of 78 strains (including 58 clinical and 20 environmental isolates) of the P. aeruginosa were collected from Beasat hospital of Hamadan, west of Iran, and was identified using API 20NE. The disk diffusion method according to the CLSI was applied for determination of the antimicrobial resistance. Moreover, the microtiter plate test was used for the quantification of Biofilm formation. The genomic features of the isolated strains was evaluated using Pulsed Field Gel Electrophoresis (PFGE). We found that 94.8% of clinical and 80% environmental isolates were capable of forming biofilm. The rate of MDR in clinical and environmental isolates was 51.7% and 40%, respectively. A significant relationship was observed between biofilm formation capability and multiple drug resistance (p < 0.05). PFGE typing showed 11 different clusters with two major clusters A with 30 (38.5%) and B with 14 (17.9%) members, containing up to 56.4% of all isolates. There was no relationship between biofilm formation ability and antibiotic resistance patterns with PFGE patterns. According to the results, the clonal spread of environmental P. aeruginosa isolates is associated with clinical isolates, and both environmental and clinical isolates are attributed to a high prevalence of the antibiotic resistance and biofilm formation ability. This study highlighted that the prevention programs should be implemented in the hospital environment to control the spread of P. aeruginosa in burn units.

Multidrug Resistant Pseudomonas aeruginosa in Iran: A Systematic Review and Metaanalysis

Background:

Multidrug-resistant Pseudomonas aeruginosa (MDR P. aeruginosa) is known as a serious threat to human health worldwide. Limited information is available concerning the prevalence of MDR P. aeruginosa in Iran. The aim of the present study was to investigate the relative frequency of MDR P. aeruginosa in different parts of Iran.

Materials and Methods:

Using appropriate keywords and well-known English and Persian database, available data about MDR P. aeruginosa in Iran were retrieved. After applying predefined criteria, relevant studies were selected.

Results:

By using random-effect models, the pooled incidence of MDR P. aeruginosa was estimated 58% (95% confidence interval [CI]; 0.54–0.61). The highest and lowest prevalence of MDR P. aeruginosa were observed in Tehran (100%) (95% CI; 0.94–1.00) and Zahedan (16%) (95% CI; 0.10–0.24), respectively. The highest resistance rate was against ceftazidime (50%) (95% CI; 0.46–0.54) and amikacin (50%) (95% CI; 0.46–0.54).

Conclusion:

Our findings are of concern since they demonstrate the high prevalence rate of MDR P. aeruginosa in the majority of Iranian hospitals.

EXTENDED-SPECTRUM BETA-LACTAMASE PRODUCING GRAM NEGATIVE BACTERIA IN IRAN: A REVIEW

Background:

The emergence and spread of extended spectrum β-lactamase (ESBL)-producing Gram- negative bacteria (GNB), particularly in Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa, have increased all over the world. ESBLs are characterized by their ability to hydrolyze β-lactams, early cephalosporins, oxyimino-thiazolyl cephalosporins, and monobactams, but not cephamycins or carbapenems. The rate of nosocomial infections caused by ESBL-producing GNB in Asia Pacific has increased and several studies have identified their prevalence in the region. The aim of this study is to review the prevalence of ESBL-producing GNB in the West Asia and the Middle East with a particular focus on Iran.

Materials and Methods:

The available evidence from various studies (Microbia and clinical studies, retrieved from the PubMed, and Scopus databases) regarding the ESBL producing Gram negative bacteria in Iran were evaluated.

Results:

In almost all parts of the country, high resistance has been observed, especially in the central part of Iran. Up to 89.8% Escherichia coli, 72.1% Klebsiella pneumonia, 84.2% Acinetobacter baumannii, and 83.8% Pseudomonas aeruginosa isolates are ESBL positive.

Conclusion:

The present study showed the increasing prevalence of ESBLs in different regions of Iran, which could be useful to strategic policy towards reducing reduce their prevalence.

Systematic review and meta-analysis of imipenem-resistant Pseudomonas aeruginosa prevalence in Iran

INTRODUCTION

Imipenem-resistant Pseudomonas aeruginosa (IRPA), due to resistance to different classes of antibiotics and its remarkable capacity to survive in harsh and adverse conditions such as those in the hospital environment, is considered a serious threat to the healthcare system. Given the great impact of IRPA on patients' outcome and in order to possibly improve antibiotic prescription, this study was conducted to determine the prevalence of clinical isolates of IRPA in different parts of Iran.

METHODS

A systematic literature search was performed in PubMed, Web of Science, Google Scholar and Scopus, as well as in two Iranian domestic search engines, i.e., Iranian Scientific Information Database and Magiran. Finally, after applying exclusion and inclusion criteria 37 articles with full-texts describing the prevalence of imipenem-resistant P. aeruginosa were selected for meta-analysis and systematic review.

RESULTS

The pooled estimation of 5227 P. aeruginosa isolates in this analysis showed that the percentage of imipenem-resistant P. aeruginosa is about 54% in the Iranian population (95%CI: 0.47-0.62, logit event rate=0.19, 95%CI: -0.12,0.49).

CONCLUSION

The findings of this analysis show that in the majority of Iranian hospitals the relative frequency of IRPA is high, therefore, in order to prevent further dissemination of IRPA, more appropriate antibiotic prescription and infection control policies must be implemented by decision-makers.

Correlation between ability of biofilm formation with their responsible genes and MDR patterns in clinical and environmental Acinetobacter baumannii isolates

Acinetobacter baumannii potential to form biofilm and exhibit multiple antibiotic resistances may be responsible in its survival in hospital environment. Accordingly, our study was aimed to determine the correlation between ability of biofilm formation and the frequency of biofilm related genes with antibiotic resistance phenotypes, and also the categorization of their patterns in clinical and environmental isolates. A total of 75 clinical and 32 environmental strains of the A. baumannii were collected and identified via API 20NE. Antibiotic susceptibility was evaluated by disk diffusion and microdilution broth methods. Biofilm formation assay was performed by microtiter plate method. OXA types and biofilm related genes including Bla_OXA-51, Bla_OXA-23, Bla_OXA-24, Bla_OXA-58, bap, bla_PER-1, and ompA were amplified by PCR. The rate of MDR A. baumannii in clinical isolates (100%) was higher than environmental (81.2%) isolates (p < 0.05). Among 10 antibiotypes, the predominant resistance pattern in clinical and environmental isolates was antibiotypes I (85.3 and 78.1%, respectively). Analysis of the frequency of bla_OXA-23 gene revealed a statistically significant difference between clinical (85.3%) and environmental (68.7%) isolates (p < 0.05). The prevalence of strong biofilm producers in clinical and environmental isolates were 31.2%-58.7%, respectively. In the clinical and environmental isolates, the frequencies of ompA, bla_RER-1 and bap genes were 100%, 53.3%, 82.7% and 100%, 37.5%, 84.4% respectively. Statistical analysis revealed a significant correlation between the frequency of MDR isolates and biofilm formation ability (p = 0.008). The high frequency of antibiotype I would be indicated that an outbreak has been happened earlier and an endemic strain is currently being settled in the hospital environment. It would be suggested that if there was no difference in the frequency of pattern I and biofilm formation ability between clinical and environmental isolates, it is a critical point representing the higher risk of bacterial transmission from environment to the patients. The resulting data would be assisted in the improvement of disinfection strategies to better control of nosocomial infections. One dominant resistance pattern has shown among clinical and environmental isolates. The frequency of blaOXA-23 had significant difference between clinical and environmental isolates. The presence of bap gene in the A. baumannii isolates was associated with biofilm formation. There was a significant correlation between multiple drug resistance and biofilm formation. The clinical isolates had a higher ability to form strong biofilms compared to the environmental samples.

Antibiotic susceptibility pattern and analysis of plasmid profiles of Pseudomonas aeruginosa from human, animal and plant sources

Multidrug resistant organisms (MDROs) constitute a major public health threat globally. Clinical isolates of Pseudomonas aeruginosa remains one of the most studied MDROs however there is paucity of information regarding the susceptibility of its animal and plants isolates to antipseudomonas drug in Nigeria. From a total of 252 samples consisting of plants, animals and clinical samples, 54, 24 and 22 P. aeruginosa were isolated from vegetables, animals and clinical sources respectively. All the isolates were identified by standard biochemical methods. Antimicrobial susceptibility testing (AST) of the 100 P. aeruginosa isolates against 7 antipseudomonal drugs was carried out by disk diffusion method, the phenotypic detection of ESBL was done by double disk synergy test (DDST) while plasmid extraction on 20 selected isolates based on their resistance to 2 or more classes of antibiotics was carried out by alkaline lysis method and analysed with Lambda DNA/Hind lll marker respectively. The AST results revealed highest resistance of 91 and 55 % to ceftazidime and carbenicillin respectively while highest susceptibilities of 99 % for piperacillin–tazobactam and imipenem were recorded in overall assay. Fifteen out of 100 isolates specifically (10) from vegetables, (3) clinical and (2) poultry isolates showed synergy towards the beta-lactamase inhibitor indicating production of ESBL by DDST method. Detection of plasmids was among vegetable (n = 4), poultry (n = 4), cow (n = 3) and clinical isolates (n = 1). Plasmid profile for the selected isolates revealed 6 of the strains had one plasmids each while 5 strains possessed 2–4 plasmids and 1 strain had 5 plasmids. The sizes of the plasmid range from <1 to ≥23kbp. Detection of ESBL and Plasmids among the investigated isolates is suggestive of multiple interplay of resistance mechanism among the isolates. Plants and animal isolates of P. aeruginosa harbouring multiple mechanisms of resistance is of concern due to the danger it poses on the public health.

Mortality attributable to carbapenem-resistant Pseudomonas aeruginosa bacteremia: a meta-analysis of cohort studies

Whether carbapenem resistance is associated with mortality in patients with Pseudomonas aeruginosa bacteremia is controversial. To address this issue, we conducted a systematic review and meta-analysis based on cohort studies. We searched PubMed and Embase databases to identify articles (up to April 2015). The DerSimonian and Laird random-effect model was used to generate a summary estimate of effect. Associations were evaluated in subgroups based on different patient characteristics and study quality criteria. Seven studies with a total of 1613 patients were finally included, of which 1 study had a prospective design, and the other 6 were retrospective. Our meta-analysis showed patients with carbapenem-resistant P. aeruginosa bacteremia were at a higher risk of death compared with those with carbapenem-susceptible P. aeruginosa bloodstream infections (pooled odds ratio (OR) from three studies reporting adjusted ORs: 3.07, 95% confidence interval (CI), 1.60-5.89; pooled OR from 4 studies only reporting crude ORs: 1.46, 95% CI, 1.10-1.94). The results were robust across a number of stratified analyses and a sensitivity analysis. We also calculated that 8%-18.4% of deaths were attributable to carbapenem resistance in four studies assessing the outcome with 30-day mortality, and these were 3% and 14.6%, respectively, in two studies using 7-day mortality or mortality during bacteremia as an outcome of interest. Carbapenem resistance had a deleterious impact on the mortality of P. aeruginosa bacteremia; however, the results should be interpreted cautiously because only three studies reporting adjusted ORs were included. More large-scale, well-designed prospective cohorts, as well as mechanistic studies, are urgently needed in the future.

Morphological and Bactericidal Effects of Amikacin, Meropenem and Imipenem on Pseudomonas aeruginosa

Background:

Pseudomonas aeruginosa might be converted to coccoid bacteria under antibiotic stress. Bacterial conversion would increase resistance to antibiotics due to changes in cell wall crosslink or decreased metabolic activity. Morphology of P. aeruginosa under stress conditions (presence of antibiotics) can be changed to elongated bacilli, U shape and finally coccoid bacteria. Results of several researches showed that coccoid bacteria are one of the most important aspects of drug resistance. It would be the major reason for treatment failure.

Objectives:

The aim of this study was to determine in vitro morphological and bactericidal effects of amikacin, meropenem and imipenem on P. aeruginosa isolated from clinical specimens.

Materials and Methods:

Eight P. aeruginosa isolates obtained from clinical samples of burned patients and standard strain ATCC 27853 were used in this study. Isolates were identified by biochemical tests and confirmed by PCR method using ITS specific primer. Minimum inhibitory concentrations (MICs) of three antibiotics were determined by E-test method. Bacteria were exposed to antibiotics at different concentrations. Bacterial morphology in different days was examined by specific microscope and viability of isolates was examined by flow cytometry

Results:

All used antibiotics at sub MIC concentration had capability to induce coccoid bacteria. The highest rate of induced coccoid bacteria was 98.2% after 8 days, with contribution of imipenem and meropenem at 2 μg/mL concentration. Amikacin at 4 μg/mL concentration induced lower rate of coccoid bacteria (55.05%). Amikacin had a strong bactericidal effect on coccoid bacteria at 8 μg/mL concentration. Imipenem and meropenem showed very weak bactericidal effect on coccoid bacteria.

Conclusions:

Induction of coccoid form of P. aeruginosa may be one of the important reasons for antibiotic treatment failure; therefore, prescribed dose of antibiotics should be carefully managed to prevent increasing antibiotic resistance and coccoid bacteria induction.

Clonal Relatedness among Imipenem-Resistant Pseudomonas aeruginosa Isolated from ICU-Hospitalized Patients

Imipenem-resistant Pseudomonas aeruginosa (P. aeruginosa) has become an increasingly important problem in healthcare settings worldwide. The aim of the present study was to evaluate clonal spread among imipenem-resistant P. aeruginosa isolated from ICU-hospitalized patients. Totally, 150 wound specimens were analyzed. Antibiotic resistance profiles and clonal diversity were evaluated using Kirby-Bauer's disk diffusion method and Random Amplified Polymorphic DNA- (RAPD-) PCR, respectively. The isolates showed a high frequency of antibiotic resistance against meropenem, and imipenem (100%) followed by ciprofloxacin, and ceftazidime (90%); meanwhile resistance to polymyxin B was not observed. Eighteen (40%) of P. aeruginosa isolates were MBL-positive via ethylenediaminetetraacetic acid (EDTA) combined disk test. Our findings showed high genetic diversity, with 37 different RAPD types detected. RAPD typing results showed cross-acquisition of P. aeruginosa in investigated hospital, suggesting failure in infection control practices. Incidence of MBL-positive isolates is high and should be regarded as a threat to hospitalized patients.

Characterization of Multidrug Resistant Extended-Spectrum Beta-Lactamase-Producing Escherichia coli among Uropathogens of Pediatrics in North of Iran

Escherichia coli remains as one of the most important bacteria causing infections in pediatrics and producing extended-spectrum beta-lactamases (ESBLs) making them resistant to beta-lactam antibiotics. In this study we aimed to genotype ESBL-producing E. coli isolates from pediatric patients for ESBL genes and determine their association with antimicrobial resistance. One hundred of the E. coli isolates were initially considered ESBL producing based on their MIC results. These isolates were then tested by polymerase chain reaction (PCR) for the presence or absence of CTX, TEM, SHV, GES, and VEB beta-lactamase genes. About 30.5% of isolated E. coli was ESBL-producing strain. The TEM gene was the most prevalent (49%) followed by SHV (44%), CTX (28%), VEB (8%), and GES (0%) genes. The ESBL-producing E. coli isolates were susceptible to carbapenems (66%) and amikacin (58%) and showed high resistance to cefixime (99%), colistin (82%), and ciprofloxacin (76%). In conclusion, carbapenems were the most effective antibiotics against ESBl-producing E. coli in urinary tract infection in North of Iran. The most prevalent gene is the TEM-type, but the other resistant genes and their antimicrobial resistance are on the rise.