Phenotypic and molecular characterization of Acinetobacter baumannii isolates causing lower respiratory infections among ICU patients

BACKGROUND

Multi-drug resistant Acinetobacter baumannii has emerged as important nosocomial pathogen associated with various infections including lower respiratory tract. Limited therapeutic options contribute to increased morbidity and mortality. Acinetobacter baumannii has the ability to persist in the environment for prolonged periods. Breach in infection control practices increases the chances of cross transmission between patients and inter/intraspecies transmission of resistance elements. The present prospective work was conducted among patients with lower respiratory tract infections (LRTI) in the intensive care unit (ICU) to study the etiology with special reference to Acinetobacter baumannii and the role of immediate patient environment in the ICU as possible source of infection. Acinetobacter baumannii were characterized for antimicrobial susceptibility, mechanism of carbapenem resistance and virulence determinants. Molecular typing of the clinical and environmental isolates was undertaken to study the probable modes of transmission.

MATERIALS AND METHODS

Appropriate respiratory samples from 107 patients with LRTI admitted to ICU during September 2016 to March 2017 were studied for likely bacterial pathogens. Environmental samples (n = 71) were also screened. All the samples were processed using conventional microbiological methods. Consecutive Acinetobacter spp. isolated from clinical and environmental (health care workers and environment from ICU) samples were included in the study. Antimicrobial susceptibility was performed as per CLSI guidelines. Carbapenem resistance, mediated by carbapenemase genes (bla_OXA-23-like,bla_OXA-24-like,bla_OXA-58-like and bla_NDM-1) were studied by PCR. Biofilm forming ability was tested phenotypically using microtitre plate method. Pulse Field Gel Electrophoresis (PFGE) was used to study clonality of the clinical and environmental isolates.

RESULTS

The prevalence of Acinetobacter baumannii was 26.2% (28/107) and 11.26% (8/71) among patients with LRTI and environmental samples respectively. The carbapenem resistance was high, 96.42% (27/28) and 87.5% (7/8) in clinical and environmental isolates respectively. The most common carbapenemase associated with resistance was bla_OXA-23-like gene followed by bla_NDM-1 among both the clinical and environmental isolates. All isolates were sensitive to colistin (MIC ≤ 1 μg/ml). Biofilm production was observed among all clinical (n = 28) and 87.5% (7/8) of the environmental isolates. Line listing of the cases suggests the occurrence of infections throughout the study period with no significant clustering. On PFGE, 12 clusters were observed and 16/36 isolates were present in one single cluster that included both clinical and environmental isolates which were either carbapenem resistant or sensitive.

DISCUSSION

Carbapenem resistant Acinetobacter baumannii (CRAB) is an important cause of LRTI in the ICU. PFGE suggests spread of carbapenem resistant isolates via cross transmission among patients and the environment. The detection of bla_NDM-1 gene among Acinetobacter baumannii and existence of carbapenem resistant and sensitive isolates within the same clones suggests horizontal transmission of resistant genes among various bacterial species. The ability of Acinetobacter baumannii to form biofilms may contribute to its persistence in the environment. This along with breach in infection control practices are the likely factors contributing to this transmission. This information can be used to strengthen and monitor infection control (IC) and the hospital cleaning and disinfection practices to prevent spread of resistant organisms within the ICU. Colistin remains drug of choice for management of CRAB.

Molecular mechanisms of antimicrobial resistance in Acinetobacter baumannii, with a special focus on its epidemiology in Lebanon

Acinetobacter baumannii is an opportunistic bacterium involved in several types of infection with high mortality and morbidity, especially in intensive care units. Treatment of these infections remains a challenge due to the worldwide emergence of broad-spectrum resistance to many antibiotics. Following the implementation of molecular techniques to study A. baumannii outbreaks, it has been shown that they are mainly caused by specific clones such as international clones I, II and III. The present work aims to review the available data on the mechanisms underlying antimicrobial resistance in A. baumannii, with a special focus on the molecular epidemiology of this species in Lebanon.

High prevalence and clonal dissemination of OXA-72-producing Acinetobacter baumannii in a Chinese hospital: a cross sectional study

BACKGROUND

Carbapenem resistance in Acinetobacter baumannii in China was mainly mediated by OXA-23-like carbapenemases, while OXA-24/40-like carbapenemases were rarely identified. OXA-72 is one variant of OXA-24/40-like carbapenemases. This study aimed to demonstrate the epidemiology and characterizations of OXA-72-producing A. baumannii in a Chinese hospital.

METHODS

A total of 107 clinical A. calcoaceticus-A. baumannii (Acb) complex isolates were collected in a Chinese hospital during between 2014 and 2016. These isolates were identified using Vitek 2 system and gyrB multiplex PCR. Vitek 2 system was used for antibiotic susceptibility testing. Genes encoding for major classes of carbapenemases were investigated by PCR. Rep-PCR was used for genotyping of all the A. baumannii isolates. The risk factors for carriage of OXA-72-producing or OXA-23-producing A. baumannii were analyzed through univariate and multivariate logistic regression.

RESULTS

Of the 107 Acb isolates collected, 101 isolates (94.4%) and 6 isolates (5.6%) were identified as A. baumannii and A. pittii, respectively. 78 A. baumannii isolates (77.2%) were carbapenem resistant and mainly cultured from intensive care unit (ICU). blaOXA-72 and blaOXA-23 genes were identified in 45(57.7%) and 33(42.3%) carbapenem-resistant A. baumannii (CRAB), respectively. Multivariate risk factor analyses showed that prior carbapenem usage and nasogastric intubation were significantly associated with carriage of OXA-72-producing A. baumannii or OXA-23-producing A. baumannii. Rep-PCR analysis showed that 9 and 22 Rep-PCR types were assigned to 78 CRAB isolates and 23 carbapenem-susceptible A. baumannii (CSAB) isolates, respectively. A higher diverstiy of Rep-PCR patterns was observed among OXA-72-producing A. baumannii isolates than OXA-23-producing A. baumannii isolates, but all of them belonged to the same clone complex. MLST analysis suggested that the OXA-72 isolates from this study correspond to CC92/CC2 clone complex.

CONCLUSIONS

This study demonstrates high prevalence and potential clonal spread of closely related genotypes of OXA-72-producing A. baumannii within a Chinese hospital. Continuous surveillance is necessary to monitor the dissemination of these strains in other healthcare settings to guide infection control policies in order to curb the spread of this bacterium.

The natural environment as a reservoir of pathogenic and non-pathogenic Acinetobacter species

Acinetobacter is a genus of Gram-negative bacteria, which are oxidase-negative, exhibiting a twitching motility under a magnifying lens. Besides being important soil microorganisms, due to their contribution to the soil fertility, Acinetobacter species, particularly A. baumannii, hold a prominent place within the genus because, it is the most virulent among the other species, causing varying degrees of human infections in clinical environments. However, results of different research have shown that Acinetobacter species can be isolated from such natural environments as surface water, wastewater and sewage, healthy human skin, plant, animal and food material as well as domestic appliances. The presence of some other Acinetobacter species in the natural environment has been associated with beneficial roles including soil improvement, detoxification of oil spillages and as microflora in human and plant bodies. In this paper, we carried out an overview of various natural ecological niches as reservoirs of pathogenic and non-pathogenic Acinetobacter species.

Management of carbapenem-resistant Acinetobacter baumannii epidemic in an intensive care unit using multifaceted intervention strategy

BACKGROUND/AIMS

We evaluated the effects of a multifaceted intervention for controlling a carbapenem-resistant Acinetobacter baumannii (CRAB) epidemic in an intensive care unit (ICU) with no restrictions on carbapenem use.

METHODS

This study was conducted in a medical ICU between April 2012 and June 2016. The baseline infection control programs included surveillance cultures, contact precautions, and environmental cleaning. However, increases in the detection of CRAB isolates beginning in May 2013 led to the implementation of a new protocol, consisting of universal glove and gown use with daily chlorhexidine bathing for all patients in combination with baseline programs. The efficacy of the intervention was subjected to interrupted time series (ITS) analysis.

RESULTS

The multifaceted intervention led to a decrease in the incidence of CRAB from 17.65 to 0.89 cases per 1,000 patient-days, during the study period (p < 0.001). ITS analysis revealed a significant change in the trend of CRAB incidence (-0.413, p < 0.001). Over this same period, mean monthly use of carbapenems increased from 143.54 ± 95.73 to 204.95 ± 78.43 doses per 1,000 patient-days (p = 0.018).

CONCLUSION

Our multifaceted intervention reduced the incidence of CRAB acquisition in an ICU where carbapenem use was not restricted.

Prevalence of metallo‑beta‑lactamase producing Acinetobacter baumannii isolated from intensive care unit in tertiary care hospitals

INTRODUCTION

The emergence of Metallo-beta-lactamase (MBL)-producing Acinetobacter baumannii has become a global concern in nosocomial infections. The aim of this study is to determine the prevalence of MBL producing genes among clinical isolates of A. baumannii from hospitalized patients.

METHODS

This study was performed from October 2015 to October 2016 at three teaching hospitals located in Isfahan, Iran. Totally, 100 A-baumannii isolates were collected from clinical specimens and identified as A-baumannii using standard microbiological methods. Antimicrobial susceptibility test was determined by disc diffusion method according to the CLSI. Furthermore, the determination of bla _IMP-1, bla _IMP-2, bla _VIM-1, bla _VIM-2and bla _SIM-1 was detected by PCR.

RESULTS

Totally, Sixty-eight percent (68%) of isolates of A. baumannii were recovered from tracheal aspirate. According to the antibiotic susceptibility pattern, the highest level of resistance was against ciprofloxacin (99%), while among tested antibiotics amikacin (10%) was found to be the most effective. 21%, 4%, 7% and 6% isolates carried bla _IMP-1, bla _IMP-2, bla _VIM-1 and bla _VIM-2 genes, respectively. Also, bla _SIM-1 was not detected in any of the isolates.

CONCLUSION

The results of this study showed high rate of the MBL producing A-baumannii isolates in our region and displayed that MBLs producing A-baumannii strains are emerging threats to ICUs.

Alarming rates of antimicrobial resistance and fungal sepsis in outborn neonates in North India

BACKGROUND

There is a paucity of data on the epidemiology of sepsis in outborn neonates being referred to level-3 units in low- and middle-income countries (LMIC). The objective of the present study was to evaluate the prevalence of sepsis and outcomes of outborn neonates with sepsis, and to characterize the pathogen profile and antimicrobial resistance (AMR) patterns of common isolates in them.

METHODS

In this prospective observational cohort study (2011-2015), a dedicated research team enrolled all neonates admitted to an outborn level-3 neonatal unit and followed them until discharge/death. Sepsis work-up including blood culture(s) was performed upon suspicion of sepsis. All the isolates were identified and tested for antimicrobial susceptibility. Gram-negative pathogens resistant to any three of the five antibiotic classes (extended-spectrum cephalosporins, carbapenems, aminoglycosides, fluoroquinolones, and piperacillin-tazobactam) were labeled multi-drug resistant.

RESULTS

Of the total of 2588 neonates enrolled, culture positive sepsis and total sepsis-i.e. culture positive and/or culture negative sepsis-was diagnosed in 13.1% (95% CI 11.8% to 14.5%) and 54.7% (95% CI 52.8% to 56.6%), respectively. The case fatality rates were 23.4% and 11.0% in culture-positive and total sepsis, respectively. Sepsis accounted for two-thirds of total neonatal deaths (153/235, 63.0%). Bacterial isolates caused about three-fourths (296/401; 73.8%) of the infections. The two common pathogens-Klebsiella pneumoniae (n = 50, 12.5%) and Acinetobacter baumannii (n = 46, 11.5%)-showed high degree of multi-drug resistance (78.0% and 91.3%, respectively) and carbapenem resistance (84.0% and 91.3%, respectively). About a quarter of infections were caused by Candida spp. (n = 91; 22.7%); almost three-fourths (73.7%) of these infections occurred in neonates born at or after 32 weeks' gestation and about two-thirds (62.1%) in those weighing 1500 g or more at birth.

CONCLUSIONS

In this large outborn cohort, we report high burden of sepsis, high prevalence of systemic fungal infections, and alarming rates of antimicrobial resistance among bacterial pathogens.

Severe infections caused by multidrug-resistant non-fermentative bacilli in southern Poland

BACKGROUND

The impact of multidrug-resistant organisms (MDROs), including non-fermentative bacilli (NFBs), is rising and underestimated, especially in intensive care units (ICUs). The growing prevalence of multidrug resistance (MDR) and extensive drug resistance (XDR) is challenging for clinicians, as the treatment options are limited.

OBJECTIVES

The purpose of this study was to analyze the extent of the epidemiological problem of multidrugresistant, extensively drug-resistant and pandrug-resistant (PDR) non-fermentative bacilli isolated from pneumonia and bloodstream infections (BSIs) in patients hospitalized in southern Poland.

MATERIAL AND METHODS

This study included 253 NFBs belonging to Acinetobacter sp. (ACI), Pseudomonas sp. (PAR), and Stenotrophomonas sp. (STM). The microorganisms were identified, and susceptibility testing was performed using a semi-automatic system. The different patterns of resistance were defined as MDR, XDR, or PDR strains. Epidemiological typing of A. baumannii from ICUs was performed by repetitive polymerase chain reaction (rep-PCR).

RESULTS

More than half of the strains (57.7%) were isolated within ICUs. ACI-strains came significantly more often from ICU wards. The highest prevalence of ACI and PAR was found in pneumonia, whereas STM dominated in BSIs. ACIs were more frequently resistant than other pathogens to all studied antibiotics except colistin (n = 76; 58.9%), and they belonged to the XDR category. DiversiLab demonstrated the presence of 2 dominant clones in the ACI group, both classified as European Clone 2 (EUII).

CONCLUSIONS

Our results indicate serious potential therapeutic problems related to high antibiotic resistance of ACI isolates. The stratification of drug resistance (MDR/XDR/PDR) may become an important tool for the assessment of public health epidemiology and microbiological hazards at the local, national, and international level. It allows clear presentation of the issues concerning the epidemiology of highly resistant bacilli, and the exchange of information between medical staff and local representatives of public health for the implementation of effective measures to reduce drug resistance.

An outbreak of bloodstream infection due to extensively resistant Acinetobacter baumannii among neonates

BACKGROUND

Extensively resistant Acinetobacter baumannii has emerged and spread worldwide as a significant cause of health care-associated infections and outbreaks. It also causes life-threatening infections among neonates, including bacteremia. The aim of this study was to investigate an outbreak of A baumannii bacteremia (ABB) among neonates.

MATERIALS AND METHODS

A retrospective, case-control study was conducted from July 2014 to July 2015 in a neonatal intensive care unit (NICU). Risk factors associated with ABB in univariate and multivariate analysis with logistic regression was performed. Molecular typing by pulsed field gel electrophoresis was used to confirm relatedness of bacteremic A baumannii strains.

RESULTS

During the 5-year period (2011-2016), 68 patients in our NICU were diagnosed with BSI due to A baumannii. The case-control study included 41 case patients within the outbreak caused by a major epidemic clone and 108 control patients. Risk factors (by univariate analysis) associated with ABB were intubation, 14-day mortality, and use of peritoneal dialysis and an umbilical catheter. Multivariate analysis identified 14-day mortality (odds ratio, 5.75; 95% confidence interval, 2.58-12.79) and umbilical catheter use (odds ratio, 2.44; 95% confidence interval, 1.1-5.4) as independent risk factors for ABB.

CONCLUSIONS

This outbreak of bacteremia due to resistant A baumannii affected 41 infants and was associated with 58% mortality. Control of the outbreak was achieved by implementing long-term sustained infection control measures within the unit.

Control of multidrug-resistant Acinetobacter baumannii in Hong Kong: Role of environmental surveillance in communal areas after a hospital outbreak

BACKGROUND

Environmental reservoir is an important source of multidrug-resistant Acinetobacter baumannii (MRAB) outbreaks. The role of postoutbreak environmental surveillance for guiding sustained infection control effort has not been examined.

METHODS

Enhanced environmental disinfection and regular environmental surveillance of ward communal areas after an outbreak were performed in a university-affiliated hospital. To assess the usefulness of environmental culture in predicting patients with MRAB, weekly surveillance of communal areas was continued for 3 months after the outbreak in intervention wards. The incidence of MRAB in intervention and nonintervention wards (control) was compared, whereas the other infection control measures remained identical.

RESULTS

Postoutbreak weekly surveillance of communal areas showed that identification of newly diagnosed MRAB patients was significantly correlated with preceding environmental contamination with MRAB (P = .001). The incidence of nosocomial MRAB infection was significantly lower in the intervention compared with nonintervention wards (0.55 vs 2.28 per 1,000 patient days, respectively; P = .04). All MRAB isolated from the environmental and patients' samples belonged to multilocus sequence typing ST457 and were blaOXA23-like positive.

CONCLUSIONS

Environmental surveillance may serve as a surrogate marker for the presence of MRAB carriers. Implementation of timely infection control measures should be guided by environmental culture for MRAB to minimize the risk of MRAB outbreak.

Changes in the incidence and antimicrobial susceptibility of healthcare-associated infections in a New York hospital system, 2006-2012

Introduction

National efforts to curtail healthcare-associated infections (HAI) proliferated recently, though data detailing progress over time are limited. This retrospective cohort study aims to describe changes in incidence and antimicrobial susceptibility of HAI in four New York City hospitals over seven years.

Methods

Electronic data were collected retrospectively for all patients discharged from 2006 through 2012. Previously validated computerized algorithms based on National Healthcare Safety Network criteria detected bloodstream infections, pneumonia, surgical site infections, and urinary tract infections with Enterococcus spp., Staphylococcus aureus, Streptococcus pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae. Antimicrobial susceptibilities were obtained from electronic laboratory records. Logistic regression was used to assess changes in odds of acquiring an HAI and odds of antimicrobial resistance over time, controlling for age, gender, severity of illness, previous hospitalizations, and admission source.

Results

In total, 19,052 HAI were identified among 761,426 discharges. HAI rates fell for all organisms, all infection types, and within all hospitals. Odds of acquiring an HAI decreased significantly over time for all organisms. Resistance levels were stable for Enterococcus spp., S. aureus, A. baumannii, and S. pneumoniae. Multidrug resistance increased for P. aeruginosa and decreased for K. pneumoniae, though imipenem resistance among K. pneumoniae climbed sharply in 2011.

Conclusions

This study suggests that HAI incidence rates are falling, possibly due to increased federal, state and local attention to healthcare quality and patient safety. Though we found no substantial reductions in resistance, recent national attention towards antimicrobial stewardship may precipitate a change in coming years.

Update on the main MDR pathogens: prevalence and treatment options

In recent years the proportion of multi-drug resistance (MDR) among the bacterial pathogens causing infections, particularly those acquired in healthcare settings, has risen worryingly worldwide. It poses a serious public health threat as the multiple patterns of resistance limit the effective treatment options for such infections. Although many bacterial species have developed reduced susceptibility to a wide array of antimicrobial molecules, a particular group of pathogens acronymically referred to as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) plays a clinically relevant role in the aetiology of life-threatening nosocomial infections. In this review, we represent the rise of MDR among the ESKAPE pathogens over the decades and report studies from each continent showing the current prevalence and burden of such infections worldwide.

[Simulation of an outbreak of Acinetobacter baumannii in hospitals]

OBJECTIVE

Acinetobacter baumannii infections have increased over time becoming a significant issue. Consequently, those applications that allow to predict the evolution of an outbreak and the relevance of the different control methods, are very important. The design of mathematical models plays a central role in this topic.

METHODS

Development of a deterministic mathematical model based on ordinary differential equations whose variables and parameters are defined upon the basis of knowledge of the epidemiology and characteristics of A. baumannii. This model is analyzed from a qualitative point of view and, also, its computational implementation is derived.

RESULTS

Several simulations were obtained developed from different initial conditions. The qualitative analysis of these simulations provides formal evidence of most effective control measures.

CONCLUSIONS

The implementation of the computational model is an extremely useful tool in terms of managing A. baumannii outbreaks. There is mathematical proof of the fact that the observance of efficient hygiene and screening rules reduces the number of infected patients.

Successful control of 2 simultaneous outbreaks of OXA-48 carbapenemase-producing Enterobacteriaceae and multidrug-resistant Acinetobacter baumannii in an intensive care unit

BACKGROUND

This report describes a double outbreak of OXA-48-producing Enterobacteriaceae (OXA-48-PE) and multidrug-resistant Acinetobacter baumannii (MRAB) in an intensive care unit (ICU) and the effectiveness of measures implemented, including decontamination with vaporized hydrogen peroxide (VHP).

METHODS

Affected patients were isolated in a confined area and cared for by dedicated personnel. Four percent chlorhexidine soap was used for patient daily hygiene. All patients are subjected to contact precautions. An in-depth cleaning of the ICU was performed with a chlorine solution, followed by decontamination with VHP. Environmental samples were taken before and after the decontamination.

RESULTS

From July-October 2015, 13 patients were colonized or infected by OXA-48-PE and 18 by MRAB in the ICU. The cumulative incidence of OXA-48-PE and MRAB was 3.48% and 4.81%, respectively. In the period after the intervention, they were 0.8% and 0%, respectively (P < .001). Before the VHP biodecontamination, 4.5% of environmental samples were positive for OXA-48-PE and none for MRAB. After biodecontamination, 1.4% of samples were positive for OXA-48-PE.

CONCLUSIONS

This study emphasizes the importance of environmental hygiene in the control of outbreaks caused by microorganisms of high environmental impact. The rapid effect after the VHP treatment suggests an influence of this measure in eradication.

High incidence of pandrug-resistant Acinetobacter baumannii isolates collected from patients with ventilator-associated pneumonia in Greece, Italy and Spain as part of the MagicBullet clinical trial

OBJECTIVES

To investigate the molecular epidemiology, antimicrobial susceptibility and carbapenem resistance determinants of Acinetobacter baumannii isolates from respiratory tract samples of patients diagnosed with ventilator-associated pneumonia (VAP) who were enrolled in the MagicBullet clinical trial.

METHODS

A. baumannii isolates were prospectively cultured from respiratory tract samples from 65 patients from 15 hospitals in Greece, Italy and Spain. Susceptibility testing was performed by broth microdilution. Carbapenem resistance determinants were identified by PCR and sequencing. Molecular epidemiology was investigated using rep-PCR (DiversiLab) and international clones (IC) were identified using our in-house database.

RESULTS

Of 65 isolates, all but two isolates (97%) were resistant to imipenem and these were always associated with an acquired carbapenemase, OXA-23 (80%), OXA-40 (4.6%), OXA-58 (1.5%) or OXA-23/58 (1.5%). Resistance to colistin was 47.7%. Twenty-two isolates were XDR, and 20 isolates were pandrug-resistant (PDR). The majority of isolates clustered with IC2 (n = 54) with one major subtype comprising isolates from 12 hospitals in the three countries, which included 19 XDR and 16 PDR isolates.

CONCLUSIONS

Carbapenem resistance rates were very high in A. baumannii recovered from patients with VAP. Almost half of the isolates were colistin resistant, and 42 (64.6%) isolates were XDR or PDR. Rep-PCR confirmed IC2 is the predominant clonal lineage in Europe and suggests the presence of an epidemic XDR/PDR A. baumannii clone that has spread in Greece, Italy and Spain. These data highlight the difficulty in empirical treatment of patients with A. baumannii VAP in centres with a high prevalence of carbapenem-resistant A. baumannii.

Carbapenemases among Acinetobacter species isolated from NICU of a tertairy care hospital in Karachi

OBJECTIVE

To determine the carbapenemases in carbapenem-resistant Acinetobacter species.

METHODS

This descriptive, cross-sectional study was carried out at the Jinnah Postgraduate Medical Centre, Karachi, from March to December 2014, and comprised Acinetobacter species isolated from the clinical specimen collected from hospitalised neonates. The screening for carbapenem resistance was performed by meropenem and imipenem discs, and minimum inhibitory concentrations. SPSS 16 was used for data analysis. .

RESULTS

A total of 100 Acinetobacter isolates were included. The patients' age ranged from 1-28 days. The main species 95(95%) was Acinetobacter calcoaceticus-baumannii complex, followed by Acinetobacter lwoffii 5(5%). The overall resistance to carbapenem was 95(95%); it was higher 100 (100%) in Acinetobacter lwoffii in comparison to Acinetobacter calcoaceticus-baumannii complex 90 (94.7%). Phenotypic characterisation revealed that 89 (93.6%) of both the species were class D carbapenemase producers, 2 (2.1%) were metallo-b-lactamases and 4 (4.2%) were non-producers.

CONCLUSIONS

Among carbapenem-resistant Acinetobacter species, the class D carbapenemases were the main mode of resistance to carbapenems.

Acinetobacter baumannii Infection in Transfusion Dependent Thalassemia Patients with Sepsis

PURPOSE

To identify the Acinetobacter baumannii infection among transfusion dependent thalassemia patients.

METHODS

A quantitative approach was employed to assess Acinetobacter baumannii infection in transfusion dependent thalassemia patients. Samples were collected from 916 patients, which have shown bacterial growth on MacConkey and blood agar culture media. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomerieux, USA) was used for final identification.

RESULTS

From 916 cultured blood specimens, 107 (11.6%) showed growth of A. baumannii. Serum ferritin in thalassemic patients without bacterial infections was 3849.5 ± 1513.5 µg/L versus 6413.5 ± 2103.9 µg/L in those with bacterial infections (p = 0.0001). Acinetobacter baumannii infected patients have shown higher serum ferritin levels (p = 0.0001). Serum ferritin in thalassemic patients was 3849.5 ± 1513.5 µg/L versus 6413.5 ± 2103.9 µg/L in those with bacterial infections (p = 0.0001). Acinetobacter baumannii infected patients showed high serum ferritin levels (p = 0.0001). The clinical symptoms have been found with A. baumannii +ve with a mean and standard deviation of 47 (5.1%) and A. baumannii -ve with mean and standard deviation of 60 (6.5%).

CONCLUSION

Isolation of asymptomatic A. baumannii from the thalassemia patients shows an alarming situation of bacterial infections. A continuous surveillance of transfusion dependent thalassemia patients is recommended for bacterial sepsis.

Antimicrobial-resistant infections among postpartum women at a Ugandan referral hospital

INTRODUCTION

Puerperal sepsis causes 10% of maternal deaths in Africa, but prospective studies on incidence, microbiology and antimicrobial resistance are lacking.

METHODS

We performed a prospective cohort study of 4,231 Ugandan women presenting to a regional referral hospital for delivery or postpartum care, measured vital signs after delivery, performed structured physical exam, symptom questionnaire, and microbiologic evaluation of febrile and hypothermic women. Malaria rapid diagnostic testing, blood and urine cultures were performed aseptically and processed at Epicentre Mbarara Research Centre. Antimicrobial susceptibility and breakpoints were determined using disk diffusion per EUCAST standards. Hospital diagnoses, treatments and outcomes were abstracted from patient charts.

RESULTS

Mean age was 25 years, 12% were HIV-infected, and 50% had cesarean deliveries. Approximately 5% (205/4176) with ≥1 temperature measurement recorded developed postpartum fever or hypothermia; blood and urine samples were collected from 174 (85%), and 17 others were evaluated clinically. Eighty-four (48%) had at least one confirmed source of infection: 39% (76/193) clinical postpartum endometritis, 14% (25/174) urinary tract infection (UTI), 3% (5/174) bloodstream infection. Another 3% (5/174) had malaria. Overall, 30/174 (17%) had positive blood or urine cultures, and Acinetobacter species were the most common bacteria isolated. Of 25 Gram-negatives isolated, 20 (80%) were multidrug-resistant and cefepime non-susceptible.

CONCLUSIONS

For women in rural Uganda with postpartum fever, we found a high rate of antibiotic resistance among cultured urinary and bloodstream infections, including cephalosporin-resistant Acinetobacter species. Increasing availability of microbiology testing to inform appropriate antibiotic use, development of antimicrobial stewardship programs, and strengthening infection control practices should be high priorities.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread.

Application of Bacteriophage-containing Aerosol against Nosocomial Transmission of Carbapenem-Resistant Acinetobacter baumannii in an Intensive Care Unit

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) is associated with nosocomial infections worldwide. Here, we used phage as a potential agent to evaluate the efficacy of daily cleaning practices combined with a bacteriophage-containing aerosol against CRAB.

METHODS

A two-phase prospective intervention study was performed at a 945-bed public teaching hospital. From March to December 2013, we performed terminal cleaning using standard procedures plus an aerosol with active bacteriophage in the intensive care units to evaluate the impact on nosocomial incidence density, carbapenem-resistance rates and antimicrobial drug consumption amounts. Patients with culture proven CRAB infection were transferred to the isolation room when the phage aerosol cleaning had been completed.

RESULTS

A total of 264 new acquisitions of CRAB were identified in the intensive care units (191 in the pre-intervention period and 73 in the intervention period). The rates of new acquisitions of CRAB in the intensive care units decreased from 8.57 per 1000 patient-days in the pre-intervention period to 5.11 per 1000 patient-days in the intervention period (p = 0.0029). The mean percentage of resistant isolates CRAB decreased from 87.76% to 46.07% in the intensive care units (p = 0.001). All of the antimicrobials showed a significant reduction in consumption except imipenem.

CONCLUSIONS

The bacteriophage was successful in decreasing the rates of infection caused by CRAB across intensive care units in a large teaching hospital.

Polymyxin B and Doxycycline Use in Patients with Multidrug-Resistant Acinetobacter baumannii Infections in the Intensive Care Unit

Background:

Multidrug-resistant Acinetobacter baumannii (MDR-Ab) has emerged as an increasingly problematic cause of hospital-acquired infections in the intensive care unit (ICU). MDR-Ab is resistant to most standard antimicrobials but often retains susceptibility to polymyxin B and doxycycline.

Objective:

To evaluate the efficacy and toxicity of polymyxin B and doxycycline in the treatment of MDR-Ab infections.

Methods:

A retrospective chart review was conducted between March 2002 and May 2005 in patients who received doxycycline or polymyxin B for treatment of MDR-Ab infections in ICUs within Grady Memorial Hospital, Atlanta, GA.

Results:

Thirty-seven patients with MDR-Ab infections were treated with polymyxin B or doxycycline. Median age was 41 years and median ICU length of stay was 18 days prior to acquisition of MDR-Ab. Clinical cure was observed in 22 of 29 (76%) evaluable patients treated with polymyxin B and 2 of 4 (50%) patients treated with doxycycline. In patients with follow-up cultures, microbiological cure was observed in 17 of 21 (81%) patients treated with polymyxin B and 2 of 3 (67%) patients treated with doxycycline. Nephrotoxicity developed in 21% (7 of 33) of patients who received polymyxin B. Neurotoxicity was observed in 2 (6%) patients who received polymyxin B. No adverse reactions were observed with doxycycline. Overall, crude mortality was 27% (9 of 33) and 75% (3 of 4) among those who received polymyxin B and doxycycline, respectively. Three (9%) deaths were attributed to polymyxin B treatment failure, and no deaths were attributed to doxycycline treatment failure.

Conclusions:

Polymyxin B was effectively used to treat a substantial proportion of critically ill patients with MDR-Ab infection and was associated with a similar rate of nephrotoxicity as previously reported. Doxycycline monotherapy was used in a limited number of patients for the treatment of MDR-Ab; further evaluation of its efficacy in larger numbers of patients is warranted.

Surveillance for and susceptibility of Acinetobacter baumannii in a large hospital and burn center in Shanghai, China, 2007-2013

Knowledge of epidemiology and microbial resistance helps clinicians carry out appropriate infection control strategies. A retrospective study in a comprehensive hospital, including a burn center, and using CHINET (the surveillance system for bacterial epidemiology and resistance in China) from 2007-2013 revealed that gram-negative Acinetobacter baumannii in the burn center demonstrated higher resistance rates to ceftazidime, amikacin, ciprofloxacin, imipenem, and cefoperazone-sulbactam compared with the hospital and CHINET data. The high rate of antibiotic use in the burn center may have contributed to these results.

Risk factors and epidemiology of Acinetobacter baumannii infections in a university hospital in Northern Italy: A case-control study

BACKGROUND

Acinetobacter baumannii has emerged as a major cause of outbreaks of hospital-associated infections with increased morbidity and mortality among those affected.

METHODS

We performed a 1:1 matched case-control study involving 68 cases in a teaching hospital in Northern Italy. Risk factors included general health conditions, comorbidities, diagnostic and therapeutic procedures, and antibiotic therapies. A multiple correspondence analysis (MCA) was performed to highlight possible association patterns among risk factors. After this, a conditional logistic regression model was applied.

RESULTS

The combined results of the MCA and univariate regression models suggest that invasive procedures performed before intensive care unit admission, in particular bronchoscopy (odds ratio, 48.06) and oxygen therapy (odds ratio, 2.11), are associated with development of an infection. Malnutrition or obesity, lack of self-sufficiency, and severe liver diseases also proved to be significantly associated with infection. When analyzing antibiotic therapies, both the number of molecules administered and duration of therapy were significantly associated.

CONCLUSIONS

Early recognition of patients at high risk, environmental hygiene control measures, appropriate antibiotic prescriptions, especially regarding carbapenems, and high-quality training of health care workers in all hospital departments are all key aspects for prevention and control of Acinetobacter infection. Further studies are needed to investigate the role of antibiotics on microbial competition dynamics in relation to multidrug-resistant outbreaks.

[Notes on the Features of an Outbreak Caused by MDRA in Our Hospital]

In Japan, the criteria for multi-drug-resistant Acinetobacter baumannii (MDRA) have been developed in response to two large-scale MDRA outbreaks reported in 2010. A. baumannii can survive for a long period in a dry environment, and it is also detected frequently from carriers over a long period. For mixed infection with some other bacteria, it cannot be accurately detected due to masking by other bacteria. For these reasons, the detection of MDRP infection is delayed. Furthermore, the infection control of MDRA must require the determination of the quarantine period, release criteria, and a clean environment, without sufficient levels of evidence. It is not rare for this to take more than a year to resolve an MDRA outbreak. Therefore, it is important to monitor daily occurrence in any hospital. [Review].