Clonal spread of carbapenem resistant Acinetobacter baumannii in the patients and their environment at BMA Medical College and Vajira Hospital

OBJECTIVE

To determine the clonal spread of carbapenem-resistant Acinetobacter baumannii (CRAB) in the patients and their environment at BMA Medical College and Vajira Hospital.

MATERIAL AND METHOD

A prospective study on CRAB isolated from the clinical specimens of 30 patients and 300 from their environmental samples were carried out from September 1-15, 2008. The CRAB isolates were genotyped using PCR-based typing method.

RESULTS

Twenty-six (86.7%) and 20 (66.7%) cases of 30 patients had their environment contaminated with A. baumannii and CRAB, respectively Environmental contamination rates of A. baumannii and CRAB were 18.0% (54/300) and 13.0% (39/300), respectively. The most contaminated sites with CRAB were bedside cupboards (26.7%), followed by bedrails and bed sheets (20%), BP cuffs (16.7%), over bed tables and nurse station counters (13.3% each) and push carts (10%). Four molecular types were classified among 65 CRAB isolates. Molecular type 1 was the most prevalent (90.7%) and found in all kinds of environmental samples except patient record folder and computer keyboard/mouse. About 37% of the patients had at least one of their environmental samples contaminated with CRAB clonally related with their own types.

CONCLUSION

Clonal spread of CRAB was demonstrated to emphasize the important of hand hygiene, contact precaution and patient's environmental decontamination in controlling the spread of CRAB in the hospital.

Pan-resistant Acinetobacter infection in neonates in Karachi, Pakistan

BACKGROUND

Pan-resistant Acinetobacter infection has emerged as an important nosocomial pathogen in our inpatient neonates over the past few years.

METHODOLOGY

We performed a retrospective chart review during a five-year period (July 2003 - June 2008) of all neonates hospitalized in our neonatal intensive care unit (NICU) who developed Acinetobacter infection to identify mortality-associated risk factors in Acinetobacter neonatal infection.

RESULTS

During the five-year study period, 122 cultures from 78 neonates grew Acinetobacter. Source sites of positive culture were in the following descending order: blood (n = 57), trachea (n = 55), tissue/wound/body fluids (n = 4), eye (n = 4), urine (n = 1), and cerebrospinal fluid (n = 1). Twenty-four (31%) patients had Acinetobacter isolated from more than one site. At the time of admission the mean age was 2.08 +/- 4 days and mean weight was 1.77 +/- 0.88 kg; 75% were premature. Pan-resistance (87/122; sensitive only to Polymyxin) was present in 71% of Acinetobacter isolates. Crude mortality rate of this cohort was 47%, while 70% of patients died within four days after positive Acinetobacter culture. We identified weight of less than 1 kg on admission (p 0.06, adjusted Odds Ratio (AOR) 1.53), gestational age 28 weeks or less (p 0.011, AOR 2.88), poor perfusion (p 0.007, AOR 2.4), thrombocytopenia (p 0.01; AOR 1.6) and metabolic acidosis (p 0.01; AOR 1.67) as predictors associated with poor outcome.

CONCLUSION

Pan-resistant Acinetobacter infection is exceedingly fatal in newborns, particularly in premature and very low-birth weight neonates. Rational antibiotic use and vigilant infection control in NICUs are key to controlling multi-drug resistant Acinetobacter infection and improving clinical outcome.

[Multidrug-resistant Acinetobacter baumannii infection in respiratory intensive care unit]

Multidrug-resistant Acinetobacter boumannii is a challenge in the treatment and control of nosocomial infections. This retrospective study was aimed to investigate the prevalence of multidrug resistant A. boumannii in a respiratory intensive care unit (ICU), related risk factors and its impact on disease prognosis. Of 218 patients who were hospitalized in our ICU during the last two years; 37 (17%) patients (21 males, mean age 61.6 +/- 19.8 years) developed pneumonia and/or bacteremia due to multidrug-resistant A. baumannii. Previous antibiotic therapy was detected in 51.4% and hospitalization in 70.3% of the cases. Pneumonia (59.5%) was the most frequent cause of hospitalization and chronic obstructive pulmonary disease (21.6%) was the second one; 81.1% of patients had co-morbidity. Invasive mechanical ventilation was performed in 31 (83.7%) patients during the follow-up. Ventilator-associated pneumonia developed in 22 (59.5%) patients and bacteraemia in 9 (24.3%) patients. Multidrug-resistance was observed in 23 (62.2%) of patients. Highest rates of resistance (100%) was detected against piperacillin-tazobactam, ampicillin-sulbactam and ciprofloxacin, followed by imipenem and cefepime (78%), meropenem and ceftazidime (55%), cefoperazone-sulbactam (43%) and netilmicin (35.1). The rates of re-intubation and tracheotomy were higher in patients infected with A. boumannii compared to the control group (59.5% vs. 7.7%, p < 0.0001 and 21.6% vs. 3.9%, p = 0.001, respectively). There was no significant difference between two groups in terms of mortality, however, durations of ICU and hospital stays were longer in patients with multidrug-resistant A. baumannii infection than without infection (24.2 +/- 18.3 vs. 8.2 +/- 8.3 days, p < 0.001 and 33.3 +/- 19.8 vs. 15.4 +/- 11.4 days, p < 0.001, respectively). In conclusion, due to the high rates of drug-resistance in nosocomial A.baumannii isolates, the use of invasive procedures and durations of ICU and hospital stays exhibit an increasing trend.

The prevalence and risk factors of nosocomial Acinetobacter blood stream infections in tertiary teaching hospital in north-eastern Malaysia

Acinetobacter spp. is a known nosocomial pathogen causing a wide range of clinical diseases mainly pneumonia, wound infections and blood stream infections (BSI). A cross sectional descriptive study was performed to determine the prevalence of Acinetobacter infection in Hospital Universiti Sains Malaysia, Kelantan (HUSM). The risk factors of Acinetobacter BSI were determined by 1:1 case control analytical study, involving fifty-eight confirmed cases of Acinetobacter BSI patients compared to the cases caused by Gram-negative bacteria. The prevalence of Acinetobacter BSI in the HUSM was 6.11% (95% CI 4.88-7.53%). The attack rate of Acinetobacter BSI was 2.77 episodes per 1000 hospital admissions. Acinetobacter BSI patients were mostly located in intensive care unit and had a longer intensive care unit stay. In univariate analysis, the risk factors for Acinetobacter BSI include prior exposure to antimicrobial agents such as penicillins, aminoglycosides and cephalosporins, mechanical ventilation, presence of nasogastric tube, arterial catheter and urinary catheter. In multivariate analysis, the independent risk factors for Acinetobacter BSI were prior treatment with cephalosporins (OR 3.836 95% CI 1.657-8.881 p=0.002) and mechanical ventilation (OR 3.164 95% CI 1.353-7.397 p=0.008). This study revealed that rational use of antimicrobial agents is of paramount importance to control Acinetobacter BSI.

Antimicrobial resistance of Acinetobacter baumannii: six years of National Antimicrobial Resistance Surveillance Thailand (NARST) surveillance

OBJECTIVE

To determine the prevalence, clinical epidemiology, and antimicrobial susceptibilities of Acinetobacter baumannii in Thailand from 2000 to 2005.

MATERIAL AND METHOD

Twenty-eight hospitals participated in the National Antimicrobial Resistance Surveillance Thailand program. All data were reviewed and analyzed for the prevalence, clinical epidemiology, and antimicrobial susceptibilities of the clinical isolates of A. baumannii from 2000 to 2005.

RESULTS

The number of clinical isolates of Acinetobacter spp. increased from 8,699 isolates in 2000 to 14,071 isolates in 2005. The most common species, identified by biochemical and growth characteristics, was A. baumannii. More than 50% of all isolates were from the respiratory tract specimens. The percentage of resistance has been increasing, particularly multi-drug-resistant (MDR) or carbapenem-resistant phenotypes. Of carbapenem-resistant strains, the prevalence was 2.1% and 46.7% in 2000 and 2005, respectively. Most carbapenem-resistant strains were also MDR. The prevalence of MDR strains was highest in the Central region and Bangkok. Cefoperazone/sulbactam was the antimicrobial against largest proportion Acinetobacter spp., although the prevalence of resistance to this agent is on the upward trend.

CONCLUSION

A standardized technique to identify the organisms to the species level should be determined to be used in the surveillance system. Because the prevalence of Acinetobacter spp. resistant to multiple classes of antimicrobials including carbapenems and cefoperazone/sulbactam are increasing, there is an urgent need for a more active surveillance system, more stringent infection control efforts, and powerful antimicrobial stewardship programs in all healthcare sectors to minimize the further spread of this MDR strain.

[Study on the molecular characteristics of multidrug-resistant Acinetobacter baumannii]

OBJECTIVE

To investigate antibiotic resistance, carbapenemase genotype and the molecular epidemiology of multidrug-resistant Acinetobacter baumannii (Aba) collected from 3 military hospitals in China.

METHODS

The minimum inhibitory concentrations (MIC) were examined by ager dilution method. Genotypes of carbapenemases were amplified by multiplex PCR and its products were sequenced. PCR was used to detect per gene. Homology of the resistant isolates was analyzed by pulse-field gel electrophoresis (PFGE).

RESULTS

Among the 64 MDRA strains, 78.1% (50) strains possessed bla(OXA-23) gene, 89.1% (57) carried Class 1 integrase gene, 39.1% (25) with bla(PER-1) gene, and 1 strain with bla(OXA-58-like) gene. PFGE showed that 13 (A, B, C, D, E genotype) different clones were identified in these strains. A, B, and U clones were the predominant clones in three hospitals, respectitively.

CONCLUSION

Outbreaks of multidrug-resistant Aba occurred at 3 military hospitals with the most prevalent carbapenemase as OXA-23 enzyme. OXA-58 type of carbapenemase and per-1 in Aba were also isolated.

Prevalence and antibiotic susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae in Estonian intensive care units in comparison with European data

This prospective cohort study was performed from April to December 2003 for the purpose of collecting a maximum of 50 non-duplicate isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae from each of 4 ICUs to determine minimum inhibitory concentrations. The most prevalent species were Enterobacteriaceae (13%), K. pneumoniae and A. baumannii (both 12%). 60% of A. baumannii strains were susceptible to ampicillin/sulbactam and cefepime, 95% to meropenem and imipenem, and 75% to amikacin. 79% of P. aeruginosa strains were piperacillin/tazobactam, 58% ceftazidime, 81% meropenem, 72% imipenem, 69% ciprofloxacin and 97% amikacin susceptible. The susceptibility of K. pneumoniae to meropenem and imipenem was 99%, to ciprofloxacin was 91% and to amikacin was 98%. Gram-negative bacteria (especially K. pneumoniae and A. baumannii) were prevalent in our ICUs compared to other European studies. Carbapenem susceptibility of Estonian strains was higher, but P. aeruginosa sensitivity to ceftazidime was lower, compared to other EU countries.

Distribution of different carbapenem resistant clones of Acinetobacter baumannii in Tehran hospitals

The MICs of imipenem, meropenem, piperacillin-tazobactam, cefotaxime, polymixin B and tigecycline against 80 isolates of Acintobacter baumanii from 6 hospitals were determined. A multiplex-PCR was used to detect the genes encoding carbapenemases. Field Inversion Gel Electrophoresis (FIGE) was then used to investigate the genetic relationships among the carbapenem-resistant isolates. Only 7 isolates were resistant to polymixin B and tigecycline (MIC = 16). All isolates were positive for at least 2 carbapenemase genes. At least 10 distinct clones were detected by FIGE. A dominant pattern designated as pulsotype A consisting of 23 isolates was detected from 4 hospitals. The majority of isolates in this pulsotype had a bla(OXA-51/23-like) and bla(OXA-51/24-like) carbapenemase genes and cultured from the patients at burns and ICU. The pan drug resistant isolates belonged to different FIGE patterns. Nosocomial infections with different clones of Acintobacter baumanii occur at Tehran hospitals. However, inter-hospital transmission with certain pulsotypes is likely.

Role of tigecycline in the control of a carbapenem-resistant Acinetobacter baumannii outbreak in an intensive care unit

The incidence of Acinetobacter baumannii infection has greatly increased over recent decades with infections occurring more in critically ill hospitalised patients. Hospital outbreaks of multiple antibiotic-resistant strains are posing an increasing threat to public health. Three different outbreaks of multidrug-resistant A. baumannii (MRAB) infections involving 24 patients, aged 16-75 years occurred in the intensive care unit in the course of one year. The isolates were cultured from clinical samples and identified using automated Vitek II ID system and the API 20NE system. Susceptibility testing was done by the E-test method. Molecular typing of the isolates was determined by pulsed-field electrophoresis. Screening of both patients and the environment was carried out. The acquisition time, i.e. the time of admission to time of acquiring infection, ranged from 3 to 31 days. All isolates were multiply resistant (MRAB), including resistance to carbapenems (MRAB-C) in the majority of cases but susceptible to tigecycline, with a minimum inhibitory concentration (MIC(90)) of 2 microg/mL. The overall mortality rate was 16.7%. Time-to-clearance of the MRAB-C was 8.3 days in the first outbreak, when tigecycline was not used, and 2.8 and 3.1 days during the second and third outbreaks, respectively, when tigecycline was used, and all but one patient survived. Environmental screening revealed gross contamination of many surfaces and equipment within the unit. The outbreak strains belonged to two distinct clones (D and E) whereas the 14 environmental strains belonged to three distinct groups (A-C). The outbreak of infections treated with tigecycline was successfully eliminated in conjunction with an aggressive infection control strategy.

Gene cassette arrays, antibiotic susceptibilities, and clinical characteristics of Acinetobacter baumannii bacteremic strains harboring class 1 integrons

BACKGROUND AND PURPOSE

Acinetobacter baumannii isolates containing class 1 integrons belong to different clones, but only a few strains are successful at causing infection. This study was conducted to compare the characteristics among these clones with different epidemicity.

METHODS

Eighty eight bacteremic isolates of A. baumannii were collected in a medical center in Taiwan during a 3-year period. The gene cassettes and antibiotic susceptibilities of the bacterial isolates were delineated and the patients' characteristics were compared.

RESULTS

Class 1 integrons were detected in 75 isolates (85.2%). Most of the isolates belonged to 2 major clones, but only 1 of the 2 clones caused outbreaks in several hospitals in Taiwan. Restriction analyses of variable regions of the integron revealed identical gene cassettes among isolates within the same clone. The cassette arrays of the 3 clones were aacA4, catB8, aadA1 (clone I, epidemic clone); dhfr XII, unknown open reading frame (orfF), aadA2 (clone II, endemic clone); and aacC1, 2 unknown open reading frames (orfX, orfX'), aadA1a (clone III). The epidemic and endemic strains were multidrug resistant, but the former presented a higher resistance rate to ampicillin-sulbactam. Infections with epidemic strains were significantly associated with prior use of cephalosporins, but didn't contribute to a higher mortality rate.

CONCLUSIONS

Judicious use of cephalosporins and rapid identification using the integron typing method might be helpful for the prevention of further spread of strains with epidemic potential.

[Microbiological and epidemiological evaluation of carbapenem-resistant Acinetobacter baumannii clones isolated at an intensive care unit of a University Hospital in Buenos Aires city]

From June to December 2004, thirty-three carbapenem-resistant Acinetobacter baumannii isolates recovered from twenty nine patients at the intensive care unit in Hospital de Clínicas, Universidad de Buenos Aires, were studied. The isolates were categorized by molecular methods as: clone I (n = 14), clone IV (n = 7), clone III (n = 6), clone VI (n = 3), clone II (n = 2) and clone X (n = 1). Twenty one isolates were recovered from lower respiratory tract samples, 11 of which belonged to clone I. Clone III isolates were mainly recovered from non-respiratory samples (5/6). Clone IV isolates were recovered from patients not receiving previous imipenem therapy. The majority of the isolates belonging to clones I and IV were able to survive on inert materials for more than 5 days, whereas adhesion to catheters was observed in isolates belonging to clones I and III, especially in those related to bacteremia. Clone III isolates showed colistin, gentamicin and levofloxacin susceptibility, whereas clone I isolates and most from clone IV were only susceptible to colistin and tetracyclines.

Molecular genotyping of microbes by multilocus PCR and mass spectrometry: a new tool for hospital infection control and public health surveillance

We describe a new technology for the molecular genotyping of microbes using a platform known commercially as the Ibis T5000. The technology couples multilocus polymerase chain reaction (PCR) to electrospray ionization/mass spectrometry (PCR/ESI-MS) and was developed to provide rapid, high-throughput, and precise digital analysis of either isolated colonies or original patient specimens on a platform suitable for use in hospital or reference diagnostic laboratories or public health settings. The PCR/ESI-MS method measures digital molecular signatures from microbes, enabling real-time epidemiological surveillance and outbreak investigation. This technology will facilitate understanding of the pathways by which infectious organisms spread and will enable appropriate interventions on a time frame not previously achievable.

Colonization of a medical center in Southern Taiwan by epidemic strains of carbapenem- and multidrug-resistant Acinetobacter baumannii and the genetic organization of their integrons

A total of 46 carbapenem- and multidrug-resistant (CR- and MDR-)Acinetobacter baumannii bacteremic isolates from a Taiwanese medical center were investigated over the period 2000 to 2006 using randomly amplified polymorphic DNA (RAPD) profiling and by analysing the genetic organization of their integrons. The results of RAPD patterns revealed that before 2003 each CR- and MDR-A. baumannii bacteremic isolate was independent, but after 2003 the isolates appeared to belong in four epidemic strains and persisted in the hospital. All the CR- and MDR-A. baumannii strains harbored class I integron (intI1) genes. PCR amplification and nucleotide sequencing showed that the cassette genes of intI1 were found to form four different antibiotic-resistant gene alignments in those strains. The bla(IMP-1) gene in the cassette genes of intI1 was identified in a clone, which raised great concern that clonal spread of this strain or of an integron-mediated horizontal gene may have occurred.

Clinical characteristics of patients with Acinetobacter junii infection

BACKGROUND AND PURPOSE

Acinetobacter junii is a human pathogen but A. junii infection is rarely reported. This study aimed to delineate the characteristics of A. junii infection.

METHODS

The medical records of 34 patients who were treated at Taipei Veterans General Hospital, Taipei, Taiwan, from May 1999 to May 2007 and had A. junii isolated from sterile sites were reviewed. Isolates of A. junii were identified by using API ID 32 GN and were confirmed by analysis of the 16S-23S rRNA intergenic spacer region.

RESULTS

Thirty five infections with A. junii were identified. The most common underlying conditions included prior antibiotic use (56%), central venous catheterization (50%), and malignancy (38%). Systemic inflammatory response syndrome and shock developing within 1 week were observed in 27 (77%) and 8 (23%) episodes, respectively. Eighty percent of the infectious episodes were hospital acquired. The infections were primary bacteremia (n = 32), empyema (n = 1), peritonitis (n = 1), and keratitis (n = 1). Polymicrobial infection was present in 9 episodes (26%). A. junii isolates remained susceptible to most of the tested antimicrobial agents, but the hospital-acquired isolates had higher resistance rates than the community-acquired isolates. Four patients (11.4%) died of A. junii infection despite appropriate antimicrobial therapy for 3 patients. Shock that developed within 1 week of bacteremia was associated with a poor outcome (p = 0.01).

CONCLUSIONS

A. junii is an opportunistic pathogen that mainly affects patients who have had prior antimicrobial therapy, invasive procedures, or malignancy. Newly emerging infections caused by A. junii and the increasing antimicrobial resistance among hospital-acquired A. junii isolates should be monitored.

Epidemiologic characterization of nosocomial Acinetobacter baumannii infections in a Turkish university hospital by pulsed-field gel electrophoresis

BACKGROUND

Although members of the Acinetobacter genus are not commonly part of the human flora, their relatively high prevalence in hospital environment frequently results in colonization of the skin and respiratory tract.

OBJECTIVES

The present investigation was carried out to elucidate epidemiologic characteristics of nosocomial Acinetobacter baumannii infections in a teaching hospital.

METHODS

Epidemiologic, clinical, and demographic features of the 66 patients with A baumannii infection during a 14-month period were recorded. Antibiotic susceptibilities of the isolates were determined by the standardized disk-diffusion method, and the clonal relationship of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE).

RESULTS

The incidence of A baumannii infection was especially high in January, April, May, and June 2006. The isolates were most frequently obtained from blood and tracheal aspirates sent from the intensive care unit and neurosurgery ward. Although the most frequently identified predisposing factors were cerebrovascular disease and surgical operation, the main risk factors identified in these patients were catheterization and mechanical ventilation. Genotype analysis of the 66 A baumannii strains by PFGE revealed the circulation of 36 different PFGE types, of which type A (12) and K (17) accounted for 44% of the isolates. We found high clonal relationship (80.3%) among the typed strains. Thirteen antibiotypes were observed. Most of the isolates were multidrug resistant. Resistance to imipenem, meropenem, gentamicin, amikacin, tobramycin, netilmicin, ampicillin-sulbactam, trimethoprim-sulfamethoxazole, piperacillin-tazobactam, cefoperazone-sulbactam, ciprofloxacin, and levofloxacin were found in 44%, 47%, 47%, 84.8%, 21.2%, 3%, 62.1%, 57.6%, 94%, 62.1%, 95.5%, and 95.5% of the isolates, respectively.

CONCLUSION

The epidemiologic data obtained suggested that the increase in the number of A baumannii infections in our hospital was caused by the interhospital spread of especially 2 epidemic clones. We determined that clonally related strains can survive for a long time in our hospital and cause nosocomial infections in the predisposed patients.

[Epidemiologic analysis of increased frequency of isolation of multidrug-resistant Acinetobacter sp. using PFGE technique]

From November 2007 to November 2008, 25 multidrug resistant Acinetobacter baumanii/haemolyticus strains were isolated from 21 patients treated in the Pulmonary Diseases and Tuberculosis Hospital in Bystra. Seven cases were regarded as nosocomial infections. Most of the patients were hospitalized several times and/or admitted from other hospitals. The aim of this study was to find the reason for increasing colonization and infections with this microorganism. PFGE analysis showed high, exceeding 90% relationship among tested strains suggesting their clonal spread among patients in several hospitals in our region. Despite excessive search, no environmental reservoir of Acinetobacter was found, so cross-contamination via staff's hands was suspected the most likely source of this spread. Therefore, hand hygiene and contact isolation seemed the most relevant infection control measures.

Multidrug-resistant Acinetobacter baumannii osteomyelitis from Iraq

Multidrug-Resistant Acinetobacter baumannii Osteomyelitis from Iraq

[Multidrug resistant Acinetobacter baumannii]

Acinetobacter baumannii is a well recognized cause of nosocomial infections, particularly in intensive care units. Strains of this species can be resistant to multiple antimicrobial agents, leaving limited therapeutic options. It has been shown that multidrug resistance in A. baumannii is, although not exclusively, associated with some lineages (EU clones) spread in many European countries. Since 1991, the population structure and antimicrobial resistance of Acinetobacter hospital isolates in the Czech Republic have been systematically studied in our laboratory. It has been shown that the vast majority of Czech multidrug resistant isolates from 1991 to 2006 belonged to EU clone I or II. While clone I largely predominated among the isolates in the 1990s, a prospective study 2005-2006 has shown a recent shift towards clone II. This change was associated with the emergence of resistance to carbapenems in the Czech Acinetobacter population. As similar observations have been recently reported from other European countries, EU clone II is likely to play an important role in the spread of carbapenem resistance.

Risk factors for mortality in patients with Acinetobacter baumannii bloodstream infection with genotypic species identification

BACKGROUND AND PURPOSE

Acinetobacter baumannii is an increasingly common nosocomial infection with a high mortality rate. Identification of predictor factors of mortality from A. baumannii infection is important for the implementation of therapeutic management for patients with higher risk. However, many studies have reported data for Acinetobacter calcoaceticus-A. baumannii complex, which might lead to an uncertainty of results. In this study, we aimed to identify the predictive factors for mortality of patients infected with true A. baumannii that had been precisely identified by genotypic methodology.

METHODS

Sixty seven patients with documented A. baumannii bacteremia were identified from a medical center in northern Taiwan during the period between February 1998 and February 2001. The patients' medical records were retrospectively reviewed.

RESULTS

The risk factors associated with mortality in patients with A. baumannii bacteremia were underlying disease with malignancy, end-stage renal disease, and inappropriate antibiotic therapy. Laboratory variables, such as creatinine level, were also associated with poor prognosis by multivariate analysis.

CONCLUSIONS

Increased serum creatinine level, malignancy and inappropriate therapy within 3 days were related to increased mortality in patients with A. baumannii bloodstream infection. Physicians should be aware of patients with poor prognostic factors and initiate prompt strategies, including appropriate antimicrobial therapy, in order to reduce mortality.

[ISAba1 insertion sequence in genome of epidemically relevant Acinetobacter strains]

AIM

To detect presence of insertion sequence ISAba1 in genome of strains of Acinetobacter baumanii group isolated in hospitals.

MATERIALS AND METHODS

Amplification by polymerase chain reaction with oligonucleotide primers specific for ISAba1 region with promoter sequence was performed.

RESULTS

Insertion element ISAba1 was detected in A. baumanii strains isolated from cases of nosocomial pneumonia in 5 clinics in different regions of Russian Federation.

CONCLUSION

Summing the results of several studies, the mentioned IS element can be considered as epidemiologically relevant (but insufficient) marker of drug-resistant hospital strains of Acinetobacter.

Antimicrobial susceptibility patterns and distribution of blaOXA genes among Acinetobacter spp. Isolated from patients at Tehran hospitals

Multiple drug-resistant strains of Acinetobacter have created therapeutic problems worldwide. This study was conducted to determine the antimicrobial susceptibility patterns and prevalence of bla(OXA-type) carbapenemases among isolates of Acinetobacter spp. obtained from Iranian patients. Here, 128 Acinetobacter isolates were identified at the species level, and their susceptibilities to different antibiotics were determined using disk agar diffusion testing. Isolates were then subjected to multiplex-PCR targeting bla(OXA) genes. More than 50% of the isolates showed multidrug resistance to different antibiotics. The rates of susceptibility to imipenem, meropenem, piperacillin-tazobactam, and amikacin were 50.7, 50, 42.1, and 38.2%, respectively. The MICs of carbapenems for the resistant isolates ranged from 64 to > or = 256 microg/ml. All strains of Acinetobacter baumannii possessed a bla(OXA-51-like) gene. The co-existence of bla(OXA-51-like)/bla(OXA-23-like) and bla(OXA-51-like)/bla(OXA-24-like) was detected in 25% (n=32) and 17.9% (n=23) of the isolates, respectively. Over 70% of carbapenem-resistant strains contained at least two genes encoding OXA-type carbapenemase. Resistance to carbapenems in the population of Acinetobacter strains in Iran is high, with the majority of isolates showing multidrug resistance. A wide diversity of OXA genes exists among the strains of A. baumannii in Iran. Detection of bla(OXA-51-like) can be used as a simple and reliable method to differentiate A. baumannii strains from other species.