Genotyping methods for monitoring the epidemic evolution of A. baumannii strains.

Acinetobacter baumannii is clustered with other phenotypically similar species into what has commonly become known as the ACB complex: A. calcoaceticus, A. pittii and, A. nosocomialis. The ecology and pathology of most of these species are not well understood, mainly because current specific phenotypic techniques have, to date, been insufficient. This has inhibited both the precise identification of, as well as the ability to discriminate between, these clinically important and closely related Acinetobacter strains. However, new genotypic methods have greatly enhanced our capacity to identify the ACB complex. This has resulted in the implementation of more rational infection control programs. Several genotypic identification methods are explored in this study, including non-polymerase chain reaction (PCR)-based and PCR-based methods. These methods include ribotyping, pulsed-field gel electrophoresis, 16S rRNA identification, multilocus sequence typing, single locus sequence typing, restriction fragment length polymorphism analysis, restriction analysis of 16S-23S rRNA intergenic spacer sequences, rapid amplification of polymorphic DNA, and repetitive extragenic palindromic PCR; however, there is no current single ideal genotyping method. Each one has its own advantages and disadvantages. With this in mind we reviewed current and new genotyping methods used to characterize the Acinetobacter species.

Antimicrobial efficacy of doripenem and its combinations with sulbactam, amikacin, colistin, tigecycline in experimental sepsis of carbapenem-resistant Acinetobacter baumannii.

Acinetobacter baumannii is the most common species to have developed resistance to antibiotics. Due to increasing levels of drug resistance, the available therapeutic options are insufficient in A. baumannii infections. This study investigated the efficacy of doripenem monotherapy versus doripenem combination therapy with sulbactam, amikacin, colistin and tigecycline in experimental sepsis. A carbapenem-resistant A. baumannii was used to develop a sepsis model in 8-10-week-old Balb/c mice by intraperitoneal injection. Antibiotic therapies were initiated two hours after injection of bacterial suspension. Necropsy was performed at 24, 48 and 72 hours and cultures were made from heart, lung, liver and spleen samples. Bacterial loads of lung and liver were calculated as CFU/g. Combination therapies with doripenem were more effective than monotherapy at 24 and 48 hours of infection but no differences between groups were detected at 72 hours. The combination of doripenem with tigecycline and amikacin began to eradicate the bacterial load of lung and liver after 48 hours of infection, whereas doripenem+sulbactam and doripenem+colistin were started to eradication at 72 hours. The results of the study showed that combination therapies with doripenem are more effective than monotherapy and the combination of doripenem with tigeycline or amikacin has more rapid bactericidal effect than that with sulbactam or colistin.

Surveillance, control and management of infections in intensive care units in Southern Europe, Turkey and Iran--a prospective multicenter point prevalence study.

OBJECTIVE: We aimed to compare the features of intensive care units (ICUs), their antimicrobial resistance patterns, infection control policies, and distribution of infectious diseases from central Europe to Mid-West Asia. METHODS: A cross-sectional point prevalence study was performed in 88 ICUs from 12 countries. Characteristics of ICUs, patient and antibiotic therapy data were collected with a standard form by infectious diseases specialists. RESULTS: Out of 749, 305 patients at least with one infectious disease were assessed and 254 patients were reported to have coexistent medical problems. When primary infectious diseases diagnoses of the patients were evaluated, 69 had community-acquired, 61 had healthcare-associated, and 176 had hospital-acquired infections. Pneumonia was the most frequent ICU infection seen in half of the patients. Distribution of frequent pathogens was as follows: Enteric Gram-negatives (n = 62, 28.8%), Acinetobacter spp. (n = 47, 21.9%), Pseudomonas aeruginosa (n = 29, 13.5%). Multidrug resistance profiles of the infecting microorganisms seem to have a uniform pattern throughout Southern Europe and Turkey. On the other hand, active and device-associated infection surveillance was performed in Turkey more than Iran and Southeastern Europe (p < 0.05). However, designing antibiotic treatment according to culture results was highest in Southeastern Europe (p < 0.05). The most frequently used antibiotics were carbapenems (n = 92, 30.2%), followed by anti-gram positive agents (vancomycin, teicoplanin, linezolid, daptomycin, and tigecycline; n = 79, 25.9%), beta-lactam/beta lactamase inhibitors (n = 78, 25.6%), and extended-spectrum cephalosporins (n = 73, 23.9%). CONCLUSION: ICU features appears to have similar characteristics from the infectious diseases perspective, although variability seems to exist in this large geographical area.

Carbapenem-resistant Klebsiella pneumoniae sepsis in corticosteroid receipt mice: tigecycline or colistin monotherapy versus tigecycline/colistin combination.

This study compared the effect of monotherapy of colistin, tigecycline, and their combination in sepsis model of mice. OXA-48 producing Carbapenem-resistant Klebsiella pneumoniae (CRKP) strain was used in Balb/c mice. The mice were divided into competent and Methylprednisolone acetate (MPA)-treated groups. Each group was sub-divided into (1) colistin or (2) tigecycline monotherapy and (3) colistin/tigecycline combination therapy. After 3 hours of intraperitoneal bacterial inoculation, antimicrobials were administered, and mice were sacrificed at 24 and 48 hours Time-kill curve study demonstrated that colistin sulphate had early bactericidal activity following re-growth. In competent and MPA-treated groups of mice at 24 hours, bacterial counts in liver samples significantly lowered compared to control, however, there were no statistically differences between monotherapy and combination therapy subgroup. Bacterial count in lung samples of competent group was significantly lesser than control for all three antimicrobial subgroups at 24 hours Colistin plus tigecycline combination therapy was not superior against colistin or tigecycline monotherapy.

Withdrawal of Staphylococcus aureus from intensive care units in Turkey.

BACKGROUND: In the past, Staphylococcus aureus infections have displayed various patterns of epidemiologic curves in hospitals, particularly in intensive care units (ICUs). This study aimed to characterize the current trend in a nationwide survey of ICUs in Turkey. METHODS: A total of 88 ICUs from 36 Turkish tertiary hospitals were included in this retrospective study, which was performed during the first 3 months of both 2008 (period [P] 1) and 2011 (P2). A P value ≤.01 was considered significant. RESULTS: Although overall rates of hospital-acquired infection (HAI) and device-associated infection densities were similar in P1 and P2, the densities of HAIs due to S aureus and methicillin-resistant S aureus (MRSA) were significantly lower in P2 (P < .0001). However, the proportion of HAIs due to Acinetobacter was significantly higher in P2 (P < .0001). CONCLUSIONS: The incidence of S aureus infections is declining rapidly in Turkish ICUs, with potential impacts on empirical treatment strategies in these ICUs.

Efficacy of sulbactam and its combination with imipenem, colistin and tigecycline in an experimental model of carbapenem-resistant Acinetobacter baumannii sepsis.

BACKGROUND: In recent years, multidrug-resistant Acinetobacter baumannii has been reported as an important nosocomial pathogen, and treatment options are limited. The aim of this study was to investigate the additional effect of sulbactam on monotherapy with colistin, tigecycline and imipenem in experimental sepsis with carbapenem-resistant A. baumannii in mice. METHODS: Sepsis was developed in 8- to 10-week-old BALB/c mice by an intraperitoneal injection of A. baumannii. Antibiotic was given intraperitoneally 2 h after bacterial inoculation. Each experimental group had 15 mice and was divided into 3 subgroups. Mice were sacrificed at 24, 48 or 72 h. Lung, liver, heart and spleen samples were cultured, and homogenates of lung and liver were used to detect the number of colony-forming units per gram. Bacterial clearance was compared in lung and liver at different time points. RESULTS: Imipenem did not decrease the bacterial load, but the other antibiotics showed significant bactericidal activity compared with the control group, and the combination of imipenem with sulbactam decreased the bacterial load in lung and liver. However, the addition of sulbactam to colistin and tigecycline had no significant effect on bacterial counts. Only the addition of sulbactam to imipenem showed better bactericidal activity compared to imipenem alone. CONCLUSIONS: These results suggested that combining sulbactam with tigeycline or colistin does not increase the efficiency of these antibiotics.