Infections caused by Acinetobacter baumannii (AB), an increasingly prevalent nosocomial pathogen, have been associated with high morbidity and mortality. We conducted this study to analyze the clinical features, outcomes, and factors influencing the survival of patients with AB bacteremia. We retrospectively examined the medical records of all patients developing AB bacteremia during their hospital stay at a tertiary care hospital in Beirut between 2010 and 2015. Ninety episodes of AB bacteremia were documented in eighty-five patients. Univariate analysis showed that prior exposure to high dose steroids, diabetes mellitus, mechanical ventilation, prior use of colistin and tigecycline, presence of septic shock and critical care unit stay were associated with a poor outcome. High dose steroids and presence of septic shock were significant on multivariate analysis. Crude mortality rate was 63.5%. 70.3% of the deaths were attributed to the bacteremia. On acquisition, thirty-nine patients had septicemia. Despite high index of suspicion and initiation of colistin and/or tigecycline in 18/39 patients, a grim outcome could not be averted and thirty-seven patients died within 2.16 days. Seven patients had transient benign bacteremia; three of which were treated with removal of the line. The remaining four did not receive any antibiotics due to withdrawal of care and died within 26.25 days of acquiring the bacteremia, with no signs of persistent infection on follow up. A prolonged hospital stay is frequently associated with loss of functionality, and steroid and antibiotic exposure. These factors seem to impact the mortality of AB bacteremia, a disease with high mortality rate and limited therapeutic options.

Currently, antimicrobial resistance is one of the most prominent public health issues. In fact, there is increasing evidence that animals constitute a reservoir of antimicrobial resistance. In collaboration with the Lebanese Ministry of Agriculture, the aim of this study was to determine the prevalence of intestinal carriage of multi-drug-resistant Gram-negative Bacilli in poultry farms at the national level. Between August and December 2015, 981 fecal swabs were obtained from 49 poultry farms distributed across Lebanon. The swabs were subcultured on MacConkey agar supplemented with cefotaxime (2 μg/ml). Isolated strains were identified using MALDI-TOF mass spectrometry. Multilocus sequence typing analysis was performed for Escherichia coli. Phenotypic detection of extended spectrum β-lactamases (ESBL) and AmpC production was performed using double disk synergy and the ampC disk test, respectively. β-lactamase encoding genes bla_CTX-M, bla_TEM, bla_SHV, bla_FOX, bla_MOX, bla_EBC, bla_ACC, bla_DHA, and bla_CMY using PCR amplification. Out of 981 fecal swabs obtained, 203 (20.6%) showed bacterial growth on the selective medium. Of the 235 strains isolated, 217 were identified as E. coli (92%), eight as Klebsiella pneumoniae (3%), three as Proteus mirabilis (1%) and three as Enterobacter cloacae (1%). MLST analysis of E. coli isolates showed the presence of ST156, ST5470, ST354, ST155, and ST3224. The phenotypic tests revealed that 43.5, 28.5, and 20.5% of the strains were ampC, ESBL, and ampC/ESBL producers, respectively. The putative TEM gene was detected in 83% of the isolates, SHV in 20%, CTX-M in 53% and CMY ampC β-lactamase gene in 65%. Our study showed that chicken farms in Lebanon are reservoirs of ESBL and AmpC producing Gram-negative bacilli. The level of antibiotic consumption in the Lebanese veterinary medicine should be evaluated. Future studies should focus on the risk factors associated with the acquisition of multi-drug-resistant organisms in farm animals in Lebanon.

The worldwide increase in the emergence of carbapenem resistant Acinetobacter baumannii calls for the investigation into alternative approaches for treatment. This study aims to evaluate colistin-carbapenem combinations against Acinetobacter spp., in order to potentially reduce the need for high concentrations of antibiotics in therapy. This study was conducted on 100 non-duplicate Acinetobacter isolates that were collected from different patients admitted at Saint George Hospital-University Medical Center in Beirut. The isolates were identified using API 20NE strips, which contain the necessary agents to cover a panel of biochemical tests, and confirmed by PCR amplification of blaOXA-51-like. Activities of colistin, meropenem and imipenem against Acinetobacter isolates were determined by ETEST and microdilution methods, and interpreted according to the guidelines of the Clinical and Laboratory Standards Institute. In addition, PCR amplifications of the most common beta lactamases contributing to carbapenem resistance were performed. Tri locus PCR–typing was also performed to determine the international clonality of the isolates. Checkerboard, ETEST and time kill curves were then performed to determine the effect of the colistin-carbapenem combinations. The synergistic potential of the combination was then determined by calculating the Fractional Inhibitory Concentration Index (FICI), which is an index that indicates additivity, synergism, or antagonism between the antimicrobial agents. In this study, 84% of the isolates were resistant to meropenem, 78% to imipenem, and only one strain was resistant to colistin. 79% of the isolates harbored blaOXA-23-like and pertained to the International Clone II. An additive effect for the colistin-carbapenem combination was observed using all three methods. The combination of colistin-meropenem showed better effects as compared to colistin-imipenem (p<0.05). The colistin-meropenem and colistin-imipenem combinations also showed a decrease of 2.6 and 2.8 fold, respectively in the MIC of colistin (p<0.001). Time kill assays additionally showed synergistic effects for a few isolates, and no bacterial re-growth was detected following a 24 hour incubation. Our study showed that the combination of colistin with carbapenems could be a promising antimicrobial strategy in treating CRAB infections and potentially lowering colistin toxicity related to higher doses used in colistin monotherapy.

Acinetobacter baumannii is an opportunistic pathogen causing various nosocomial infections. The spread of multidrug-resistant A. baumannii is a major public health problem. The aim of this study was to investigate the molecular epidemiology and the genetic support of multidrug-resistant A. baumannii isolates collected from Saint-Georges Hospital in Lebanon. Between January and August 2016, 31 A. baumannii isolates were collected from sputum samples of patients infected with ventilator-associated pneumonia (VAP) and treated with colistin-carbapenem combination therapy. Antibiotic susceptibility testing was performed using the disk diffusion method. Carbapenemases, extended spectrum β-lactamases encoding genes and mcr-1/2 genes were investigated by RT-PCR and standard PCR. The epidemiological relatedness of the strains was studied using MLST analysis. Most of the isolates exhibited multidrug-resistant phenotypes. All the isolates were carbapenem-resistant and among them, 30 carried the class D carbapenemase blaoxa-23 gene while one isolate carried blaoxa-72 gene. MLST results revealed three sequence types, namely ST2, ST699, and ST627. Isolates having ST2 were the most prevalent clone (29/31, 93.5%). This study shows a nosocomial spread of multidrug-resistant A. baumannii ST2 having blaOXA-23 gene in Saint-George in Lebanon. Monitoring and control measures need to be adopted to avoid the spread of A. baumannii to patients.

Multidrug-resistant (MDR) Enterobacteriaceae can cause severe infections with high morbidity, mortality, and health care costs. Individuals can be fecal carriers of these resistant organisms. Data on the extent of MDR Enterobacteriaceae fecal carriage in the community setting in Lebanon are very scarce. The aim of this study was to investigate the fecal carriage of MDR Enterobacteriaceae among the elderly residents of two nursing homes located in north Lebanon. Over a period of 4 months, five fecal swab samples were collected from each of 68 elderly persons at regular intervals of 3-4 weeks. Fecal swabs were subcultured on selective media for the screening of resistant organisms. The phenotypic detection of extended-spectrum beta-lactamase (ESBL), AmpC, metallo-beta-lactamase (MBL), and Klebsiella pneumoniae carbapenemase (KPC) production was performed using the beta-lactamase inhibitors ethylenediaminetetraacetic acid, phenylboronic acid, and cloxacillin. A temocillin disk was used for OXA-48. Multiplex PCRs were used for the genotypic detection of ESBL and carbapenemase genes, and sequencing was performed to identify CTX-M-15. The medical records of each subject were reviewed on a regular basis in order to assess the risk factors associated with MDR Enterobacteriaceae fecal carriage. Over the study period, 76.5% of the recruited elderly persons were at least one-time carriers. A total of 178 isolates were obtained. Phenotypic testing revealed that 91.5% of them were ESBL producers, 4% were AmpC producers, 2.8% were co-producers of ESBL and AmpC, and 1.7% were co-producers of OXA-48 and ESBL. Recent antibiotic intake was found to be the only independent risk factor associated with the fecal carriage of MDR Enterobacteriaceae. The high prevalence of MDR Enterobacteriaceae detected in this study and the emergence of carbapenem resistance is alarming. Efficient infection control measures and antibiotic stewardship programs are urgently needed in these settings in order to limit the spread of resistant strains.