Antimicrobial resistance pattern of Gram-negative bacilli of nosocomial origin at 2 university hospitals in Iran

Evaluating the resistance pattern of gram-negative bacteria during three years at the nephrology ward of a referral hospital in southwest of Iran

BACKGROUND

Gram-negative bacteria are associated with an increase in rates of antibacterial resistance. In most low- and middle-income countries such as Iran, there is no continuous surveillance system for antibiotic resistance.

OBJECTIVE

The purpose of this survey was to determine the pattern of antimicrobial sensitivity of gram-negative bacteria within 3 consecutive years at a nephrology ward of Nemazee hospital in Shiraz.

MATERIALS AND METHODS

During a 3-year period from 2013 to 2015 at the adult nephrology ward, bacteriological data of all biological samples of hospitalized patients in favor of gram-negative microorganisms were analyzed retrospectively. Antimicrobial susceptibility was performed by the Kirby-Bauer disc diffusion method.

RESULTS

The most common gram negative bacterium isolated from biological samples was Escherichia coli (43.9%). The highest (86.3%-94.1%) antibacterial resistance rate was associated with Acinetobacter spp. The most frequent resistance was seen with cephalosporins. In contrast to ceftriaxone, ciprofloxacin, and trimethoprim/sulfamethoxazole, nitrofurantoin and aminoglycosides remained their acceptable activity against E. coli. At least three-fourths (75%) of Acinetobacter spp. isolates was resistant to either aminoglycosides or imipenem. All (100%) isolated Acinetobacter spp. and Pseudomonas aeruginosa species were susceptible to colistin. The rate of Acinetobacter spp. and P. aeruginosa resistant to three or more drugs was 81.7% and 74.6%, respectively.

CONCLUSIONS

The resistant rate of gram negative pathogens to different tested antibacterial agents was considerably high and has increased during the recent three years in our center.

Presence of metallo-beta-lactamases (MBL), extended-spectrum beta-lactamase (ESBL) & AmpC positive non-fermenting Gram-negative bacilli among Intensive Care Unit patients with special reference to molecular detection of blaCTX-M & blaAmpC genes

BACKGROUND & OBJECTIVES

Non-fermenting Gram-negative bacilli (NFGNB) including Pseudomonas aeruginosa and Acinetobacter baumannii have been implicated in a variety of infections, particularly in the Intensive Care Units (ICUs). This study was aimed to overview the burden of multidrug-resistant NFGNB causing infections in ICU and also to assess the occurrence of extended-spectrum beta-lactamases (ESBLs), AmpC and metallo-beta-lactamases (MBLs) among these isolates.

METHODS

Bacterial culture, identification and antibiotic susceptibility were carried out. ESBLs and AmpC were detected both phenotypically and genotypically. MBL was detected by modified Hodge and imipenem-ethylenediaminetetraacetic acid double-disc synergy test.

RESULTS

NFGNB represented 45 (37%) of total 121 Gram negative isolates. Multidrug resistance was observed in 66.9 per cent and 72.5 per cent isolates of P. aeruginosa and A. baumannii, respectively. Detection by phenotypic methods showed presence of ESBL, AmpC and MBL in 21.4, 51.1 and 21.4 per cent isolates, respectively. When detected genotypically by polymerase chain reaction, ESBL and AmpC were detected in 21.4 and 41.4 per cent of NFGNB isolates, respectively. BlaCTX-M (21.4%) was the most prevalent gene responsible for ESBL production.

INTERPRETATION & CONCLUSIONS

Most of the NFGNB isolated from ICU patients were multidrug-resistant and producers of ESBL, AmpC and MBL. A regular surveillance is required to detect ESBL, AmpC and MBL producers, especially in ICU patients.

Incidence of Multidrug-Resistant Pseudomonas Spp. in ICU Patients with Special Reference to ESBL, AMPC, MBL and Biofilm Production

BACKGROUND

Multidrug-resistant (MDR) Pseudomonas spp. have been reported to be the important cause of ICU infections. The appearance of ESBL, AmpC and MBL genes and their spread among bacterial pathogens is a matter of great concern. Biofilm production also attributes to antimicrobial resistance due to close cell to cell contact that permits bacteria to more effectively transfer plasmids to one another. This study aimed at determining the incidence of ESBL, AmpC, MBL and biofilm producing Pseudomonas spp. in ICU patients.

MATERIAL AND METHODS

The clinical specimens were collected aseptically from 150 ICU patients from February 2012 to October 2013. Identification and antimicrobial susceptibility was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. ESBLs and AmpC were detected phenotypically and genotypically. MBL was detected by modified Hodge and imipenem-EDTA double-disk synergy test.

RESULTS

Pseudomonas spp. 35(28%) were the most prevalent pathogen in ICU infections. Multidrug resistance and biofilm production was observed in 80.1% and 60.4% isolates, respectively. Prevalence of ESBL, AmpC and MBL was 22.9%, 42.8% and 14.4%, respectively. The average hospital stay was 25 days and was associated with 20% mortality.

CONCLUSIONS

A regular surveillance is required to detect ESBL, AmpC and MBL producers especially in ICU patients. Carbapenems should be judiciously used to prevent their spread. The effective antibiotics, such as fluoroquinolones and piperacillin-tazobactum should be used after sensitivity testing.

Antibiotic Resistance Patterns and Genetic Diversity in Clinical Isolates of Pseudomonas aeruginosa Isolated From Patients of a Referral Hospital, Isfahan, Iran

Background:

Pseudomonas aeruginosa is a well-known opportunistic pathogen, which affects hospitalized patients in different wards due to its natural resistance to drugs.

Objectives:

The purpose of the current study was to determine the antibiotic susceptibility profiles and genetic relatedness in P. aeruginosa isolated from patients admitted to a referral hospital in Isfahan, Iran.

Materials and Methods:

Out of 150 analyzed samples, 54 P. aeruginosa isolates were recovered and were subjected to antibiotic resistance patterns and genetic diversity determination by Kirby-Bauer’s disk diffusion method and RAPD-PCR, respectively.

Results:

The highest percentage of resistance was observed against ceftazidime and imipenem with 30 (55.6%) isolates; meanwhile all isolates were sensitive to polymyxin B. Twenty-eight (51.8%) isolates revealed resistance to all applied antibiotics. RAPD-PCR (Random Amplified Polymorphic DNA- Polymerase Chain Reaction) results showed 54 unique genotypes, which were divided into 39 clusters.

Conclusions:

Although different source of P. aeruginosa may involve in patient colonization, genetically related strains were isolated from different wards and or the same ward of the hospital. Our results pointed to the restriction of currently used antibiotics in studied hospital. We hope that our results cast light on the control and transmission of the infection in the investigated hospital.

Changes in gram negative microorganisms' resistance pattern during 4 years period in a referral teaching hospital; a surveillance study

Background and purpose

Surveillance studies evaluating antimicrobial susceptibilities are of great value in preventing the spread of resistant pathogens by elucidating the trend of resistance in commonly used antibiotics and as a consequence providing information for prescribing the most appropriate agent. This study is a longitudinal antimicrobial resistance surveillance study designed to evaluate the trend in antimicrobial resistance to gram negative microorganisms from 2007 to 2010.

Method

During a four-year period (2007–2010) isolates derived from all patients admitted to infectious diseases ward of Imam Khomeini Hospital, the major referral center for infectious disease in Iran with the highest admission rates, were evaluated. Based on disk diffusion method and zone of inhibition size, the microorganism was regarded as to be sensitive, resistant or has intermediate susceptibility to the antimicrobial agents.

Results

The widest spread Gram-negative microorganism in all of isolates taken together in our study was E.coli (30%) followed by Stenotrophomonas maltophilia in 28.6% and Enterobacter spp. in 11.9%, respectively. The susceptibility to amikacin, imipenem, piperacillin/tazobactam, and nitrofurantoin was equal or above 50% for all microorganisms over four years. However, the susceptibility to ampicillin, ampicillin/sulbactam, cefotaxim, and ceftriaxone was less than 50% in derived isolates during the study period.

Conclusion

In conclusion, the finding of the present study revealed that resistance rate to common antimicrobial agents in Iran is growing and isolates were susceptible mostly to broad-spectrum antibiotics including imipenem and piperacillin/tazobactam.

Isolation and antimicrobial susceptibility of bacteria from chronic suppurative otitis media patients in kerman, iran

BACKGROUND

Chronic supportive otitis media (CSOM) is one of the commonest illnesses in ENT practice. This study was conducted to find out the various aerobic microorganisms associated with CSOM and their current antimicrobial susceptibility patterns to commonly used antimicrobials.

METHODS

samples were collected from 117 clinically diagnosed cases of CSOM and processed according to standard protocols.

RESULTS

Out of 117 CSOM cases, 105 (86%) showed positive bacterial culture. The Staphylococcus aureus was the commonest aerobic isolate in CSOM. The sensitivity of Staphylococci spp. to commonly used antimicrobials varied from 27.2% for cefixime to 95.5% for gentamicin and coagulase positive. Pseudomonas isolates showed complete (100%) resistance to amoxicillin/clavulanate (co-amoxiclave), cloxacillin and cefixime, and high sensitivity to ciprofloxacin (95%) and cephalexin (90%).

CONCLUSION

An appropriate knowledge of antibacterial susceptibility of microorganisms would contribute to a rational antibiotic use and the success of treatment for chronic supportive otitis media.