Acinetobacter baumannii at a tertiary-care teaching hospital in Jerusalem, Israel

Detection of Extended-Spectrum β-Lactamases among Acinetobacter Baumannii Isolated from Hospitals of Qazvin, Iran

Background

Acinetobacter baumannii is a major contributor to nosocomial infections. Extended-spectrum β-lactamase (ESBL)-producing A. baumannii is spreading worldwide. We aimed to determine the frequency of ESBL-encoding genes in clinical isolates of A. baumannii and to access their clonal relationship by repetitive extragenic palindromic-PCR (rep-PCR).

Methods

In this descriptive cross-sectional study, 203 isolates of A. baumannii were collected from Qazvin hospitals. The Identification of isolates was performed by standard laboratory methods. To verify ESBL production, all isolates were screened by disk agar diffusion and confirmed by the combined disk method. Subsequently, ESBL-encoding genes were detected by PCR and sequencing. Possible clonal association of ESBL-producing isolates was evaluated using rep-PCR.

Results

Two hundred (98.5%) isolates showed reduced susceptibility to one of the antibiotics used in the ESBL screening test, of which 127 isolates (62.6%) produced ESBL. PCR results showed bla_OXA-1 (20.5%) was the most prevalent gene followed by bla_TEM-1 (20%), bla_GES-1 (15.7%), bla_CTX-M-15 (7.9%), and bla_PER-1 (1.6%). Rep-PCR results revealed that ESBL-producing isolates belonged to clones A (85%), B (13.4%), and C (1.6%).

Conclusion

Our study showed the significant presence of bla_OXA-1, bla_TEM-1, bla_GES-1, bla_CTX-M-15, and bla_PER-1 genes in ESBL-producing A. baumannii isolates in the studied hospitals. This is the first report on the emergence of bla_OXA-1 gene in these isolates in Iran. The use of comprehensive antimicrobial treatment guidelines based on laboratory data and appropriate infection control interventions are essential.

Molecular Detection of Carbapenem Resistance in Acinetobacter Baumannii Isolated From Patients in Khorramabad City, Iran

BACKGROUND

Acinetobacter baumannii is an opportunistic pathogen, which causes a wide range of infections in hospitals, especially in intensive care units. Nowadays, due to the high resistance of Acinetobacter bumanni to antibiotics, this study, in addition to the phenotypic and genotypic investigations of drug resistance, focused on determining the molecular types of Acinetobacter baumannii isolated from patients in Khorramabad city by the pulsed-field gel electrophoresis (PFGE) method.

MATERIALS AND METHODS

In this cross-sectional study, 50 samples of Acinetobacter baumannii were collected from educational hospitals in Khorramabad city, Iran, from January to August 2015. They were identified in the laboratory using biochemical tests and culture methods. After determining the drug resistance pattern by the disc diffusion method and percentage of resistance genes to carbapenems, Acinetobacter baumannii isolates were analyzed using the PFGE method using the Apa1 enzyme.

RESULTS

The highest antibiotic resistance observed for Acinetobacter baumannii strains was against ampicillin-sulbactam (100%) and aztreonam (98%). The highest sensitivity was to polymixin B (100%) and colistin (94%), and also to the OXA-51-like gene present in all samples. The OXA-23-like gene was positive in 44 (88%) samples. PFGE results showed that Acinetobacterbaumannii strains had 33 different pulsotype patterns, of which 27 patterns had more than one strain and 23 had only one strain.

CONCLUSION

Due to the high resistance of Acinetobacter baumannii and its ease of spread and its ability to transfer resistance genes, resistance control methods should be used in the disinfection of hospital areas. Hospital staff should observe hygiene standards and there should also be a reduction in antibiotic use.

The Impact of a Carbapenem-Resistant Enterobacteriaceae Outbreak on Facilitating Development of a National Infrastructure for Infection Control in Israel

In 2006 the Israeli healthcare system faced an unprecedented outbreak of carbapenem-resistant Enterobacteriaceae, primarily involving KPC-producing Klebsiella pneumoniae clonal complex CC258. This public health crisis exposed major gaps in infection control. In response, Israel established a national infection control infrastructure. The steps taken to build this infrastructure and benefits realized from its creation are described here.

The role of vancomycin in addition with colistin and meropenem against colistin-sensitive multidrug resistant Acinetobacter baumannii causing severe infections in a Paediatric Intensive Care Unit

Background

Acinetobacter baumannii has been associated with high morbidity and mortality rates, even in pediatric patients. Therapeutic options are limited, especially when the strain is multidrug resistant.

Methods

Clinical and microbiological analyses of 4 cases of systemic infections caused by multi drug resistant A. baumannii treated with colistin/vancomycin combination at a Pediatric Intensive Care Unit were performed in order to explore the potential synergistic activity of colistin plus vancomycin. All the patients were treated with colistin, meropenem and vancomycin.

Results

Four severe infections due to MDR A. baumannii were observed. All patients treated with colistin/vancomycin combination had a positive outcome with no infection relapses. Most importantly, no significant adverse events related to the simultaneous administration of COL plus VAN were observed. In our in-vitro experiments, the synergistic effect of the combination COL plus VAN showed an early bactericidal activity even at VAN concentration of 16 mg/L, which reflects the serum trough concentrations obtained in patients.

Discussion

An antimicrobial strategy based on the activity of colistin plus vancomycin was in-vitro and in-vivo effective in life-threatening infections caused by multidrug-resistant A. baumannii in a Pediatric Intensive Care Unit, in the absence of adverse effects. Colistin plus vancomycin were highly synergic and bactericidal against carbapenem-resistant, colistin sensitive A. baumannii whereas the addition of meropenem did not enhance the in-vitro activity of colistin plus vancomycin.

Conclusions

Our results confirm existing data on the potential synergistic activity of a therapeutic strategy including colistin plus vancomycin and provide important new clinical information for its potential use as a therapeutic option against MDR A. baumannii infections, especially in the pediatric population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1133-3) contains supplementary material, which is available to authorized users.

Multidrug-resistant Acinetobacter baumannii infections in lung transplant patients in the cardiothoracic intensive care unit

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacteria are a growing threat to solid organ transplantation (SOT) patients in the intensive care unit (ICU). We aimed to examine the mortality rates of gram-negative MDR bacterial infection in SOT patients compared with patient population undergoing other cardiothoracic surgeries and hospitalized under similar ICU conditions.

METHODS

A retrospective study from a single medical center, including patients with MDR Acinetobacter baumannii and carbapenem-resistant Klebsiella pneumoniae infection, hospitalized in the cardiothoracic ICU. Data were collected from computerized databases, and data were verified using the hospitalization files. Microbiological data were provided by the microbiology laboratory.

RESULTS

During the study period, 205 SOT patients and 5031 other patients were hospitalized in the cardiothoracic ICU. Active infection with gram-negative MDR bacteria was identified in 147 patients, of which 37 underwent SOT (18% of total transplant recipients) and 110 underwent another cardiothoracic surgery (2% of total patients who are not transplant recipients). Mortality rates were high among both groups of patients, with no significant difference between them.

CONCLUSIONS

Infection with resistant bacteria is more prevalent among patients following SOT compared with patients following other cardiothoracic surgeries. Mortality is high in all patients regardless of the immunocompromised condition.

Nosocomial multidrug-resistant Acinetobacter baumannii in the neonatal intensive care unit in Gaza City, Palestine

OBJECTIVES

We performed a prospective case-control study of bloodstream infections in order to determine the infection rate of Acinetobacter baumannii and to determine the risk factors associated with infection and mortality.

METHODS

Between February 2004 and January 2005, 579 consecutive blood specimens were collected from the two neonatal intensive care units (NICUs) of Al-Nasser and Al-Shifa hospitals in Gaza City.

RESULTS

Forty (6.9%) isolates of A. baumannii were obtained from neonates aged under 28 days. Of the patients, 62.5% were male and 37.5% were female. Compared to matched, uninfected controls, statistically significant risk factors were weight<1500 g (odds ratio (OR) 3.89, p<0.001), age <7 days (OR 2.33, p=0.027), median hospitalization of =20 days (OR 3.1, p=0.003), mechanical ventilation (OR 3.5, p=0.001), use of a central venous catheter (CVC; OR 10.5, p<0.001), and prior antibiotic use (OR 4.85, p=0.003). The overall mortality was also significantly different (overall mortality 37.5% in cases vs. 12% in uninfected controls; OR 4.4, p=0.001). Compared to infected controls, statistically significant risk factors were mechanical ventilation (OR 2.68, p=0.008), use of a CVC (OR 6.68, p<0.001), and prior antibiotic use (OR 5.68, p=0.001). The multidrug-resistant type was significantly associated with death in the neonates (p=0.023). The isolates of A. baumannii were resistant to commonly used antibiotics, while susceptible to meropenem (92.5%), imipenem (90%), ciprofloxacin (75%), gentamicin (57.5%), and ceftriaxone (50%).

CONCLUSIONS

The infection rate with multidrug-resistant A. baumannii is considerable and alarming in NICU infants, and is associated with significant mortality.

Acinetobacter baumannii: emergence and spread in Israeli hospitals 1997-2002

The incidence of multi-drug-resistant Acinetobacter baumannii bloodstream infections (BSIs) increased two- to four-fold in three Israeli hospitals between 1997 and 2002, accounting for 3.5-18% of all hospital-acquired BSIs. This was associated with increasing carbapenem resistance reaching 35-54%, and by a dramatic increase in carbapenem consumption. In-hospital fatality rates ranged between 47% and 58% and were significantly higher than those seen with other nosocomial Gram-negative pathogens. A. baumannii was not restricted to intensive care units, but had spread to all hospital wards. Multi-drug-resistant A. baumannii has the potential to reach endemicity in hospitals and warrants more vigorous and innovative efforts to limit its spread.

Multidrug-resistant Acinetobacter baumannii

A case-control, epidemiologic, and molecular study of nosocomial MDR A. baumannii showed the existence of multiple clones and a complex epidemiologic pattern.

To understand the epidemiology of multidrug-resistant (MDR) Acinetobacter baumannii and define individual risk factors for MDR, we used epidemiologic methods, performed organism typing by pulsed-field gel electrophoresis (PFGE), and conducted a matched case-control retrospective study. We investigated 118 patients, on 27 wards, in whom MDR A. baumannii was isolated from clinical cultures. Each case-patient had a control without MDR A. baumannii and was matched for hospital length of stay, ward, and calendar time. The epidemiologic investigation found small clusters of up to 6 patients each with no common identified source. Ten different PFGE clones were found, of which 2 dominated. The PFGE pattern differed within temporospatial clusters, and antimicrobial drug susceptibility patterns varied within and between clones. Multivariate analysis identified the following significant risk factors: male sex, cardiovascular disease, having undergone mechanical ventilation, and having been treated with antimicrobial drugs (particularly metronidazole). Penicillins were protective. The complex epidemiology may explain why the emergence of MDR A. baumannii is difficult to control.

Nosocomial multi-drug resistant Acinetobacter baumannii bloodstream infection: risk factors and outcome with ampicillin-sulbactam treatment

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii poses a therapeutic problem. The aim of this study was to assess the risk factors for nosocomial MDR-A. baumannii bloodstream infection (BSI) and the efficacy of ampicillin-sulbactam (A/S) in its treatment. Of 94 nosocomial A. baumannii BSI during the year 2000, 54% involved MDR strains, 81% of which were genetically related. Various risk factors for MDR-A. baumannii were found, of which intensive-care unit admission and prior aminoglycoside therapy were independently associated with MDR-A. baumannii acquisition on multivariate analysis. Of MDR-A. baumannii BSI cases, 65% received A/S and 35% inadequate antibiotic therapy, whereas of 43 non-MDR cases, 86% were treated according to susceptibility and 14% inappropriately with antibiotics to which these organisms were resistant. Crude mortality was comparable in the adequately treated groups. Respective mortalities among patients treated adequately and inadequately were 41.4 and 91.7% (p<0.001). Among severely ill patients, A/S therapy significantly decreased the risk of death (P=0.02 OR=7.64). MDR-A. baumannii has become highly endemic in our institution. A/S appears to be one of the last effective and safe empirical resorts for treatment of MDR A. baumannii BSI.

Acinetobacter outbreaks, 1977-2000

This review of Acinetobacter outbreaks summarizes factors related to the presence and recognition of organism transmission and describes the implementation of control and prevention measures directed at limiting spread. Exogenous transmission of Acinetobacter should be considered when infections are endemic and when case rates increase. Increasing or new antimicrobial resistances in a collection of isolates also suggest transmission, and transmission can be definitively confirmed when isolates are found to be indistinguishable from or related to one another by a discriminatory genotyping test. An investigation for a common source should be conducted. When a common source cannot be found and eliminated, or once an endemically transmitted organism is established, containment or prevention efforts may require aggressive interventions, complex interventions, or both. Colonization at multiple sites, the relative ease of induction of antibiotic resistance in the organism following patient exposure to multiple drugs, and long-term environmental survival provide enhanced opportunities for the transmission of Acinetobacter between and among patients. New approaches and interventional trials are needed to define effective measures for the prevention and control of Acinobacter infections.