Characterization of Salmonella Isolates from Various Geographical Regions of the Caucasus and Their Susceptibility to Bacteriophages

Non-typhoidal Salmonella present a major threat to animal and human health as food-borne infectious agents. We characterized 91 bacterial isolates from Armenia and Georgia in detail, using a suite of assays including conventional microbiological methods, determining antimicrobial susceptibility profiles, matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, serotyping (using the White-Kauffmann-Le Minor scheme) and genotyping (repetitive element sequence-based PCR (rep-PCR)). No less than 61.5% of the isolates were shown to be multidrug-resistant. A new antimicrobial treatment strategy is urgently needed. Phage therapy, the therapeutic use of (bacterio-) phages, the bacterial viruses, to treat bacterial infections, is increasingly put forward as an additional tool for combatting antibiotic resistant infections. Therefore, we used this representative set of well-characterized Salmonella isolates to analyze the therapeutic potential of eleven single phages and selected phage cocktails from the bacteriophage collection of the Eliava Institute (Georgia). All isolates were shown to be susceptible to at least one of the tested phage clones or their combinations. In addition, genome sequencing of these phages revealed them as members of existing phage genera (Felixounavirus, Seunavirus, Viunavirus and Tequintavirus) and did not show genome-based counter indications towards their applicability against non-typhoidal Salmonella in a phage therapy or in an agro-food setting.

Etiologic agents of central nervous system infections among febrile hospitalized patients in the country of Georgia

Objectives

There is a large spectrum of viral, bacterial, fungal, and prion pathogens that cause central nervous system (CNS) infections. As such, identification of the etiological agent requires multiple laboratory tests and accurate diagnosis requires clinical and epidemiological information. This hospital-based study aimed to determine the main causes of acute meningitis and encephalitis and enhance laboratory capacity for CNS infection diagnosis.

Methods

Children and adults patients clinically diagnosed with meningitis or encephalitis were enrolled at four reference health centers. Cerebrospinal fluid (CSF) was collected for bacterial culture, and in-house and multiplex RT-PCR testing was conducted for herpes simplex virus (HSV) types 1 and 2, mumps virus, enterovirus, varicella zoster virus (VZV), Streptococcus pneumoniae, HiB and Neisseria meningitidis.

Results

Out of 140 enrolled patients, the mean age was 23.9 years, and 58% were children. Bacterial or viral etiologies were determined in 51% of patients. Five Streptococcus pneumoniae cultures were isolated from CSF. Based on in-house PCR analysis, 25 patients were positive for S. pneumoniae, 6 for N. meningitidis, and 1 for H. influenzae. Viral multiplex PCR identified infections with enterovirus (n = 26), VZV (n = 4), and HSV-1 (n = 2). No patient was positive for mumps or HSV-2.

Conclusions

Study findings indicate that S. pneumoniae and enteroviruses are the main etiologies in this patient cohort. The utility of molecular diagnostics for pathogen identification combined with the knowledge provided by the investigation may improve health outcomes of CNS infection cases in Georgia.

Etiology of neonatal blood stream infections in Tbilisi, Republic of Georgia

BACKGROUND

Neonatal blood stream infections (BSI) are a major cause of morbidity and mortality in developing countries. It is crucial to continuously monitor the local epidemiology of neonatal BSI to detect any changes in patterns of infection and susceptibility to various antibiotics.

OBJECTIVES

To examine the etiology of BSI in two neonatal intensive care units (NICUs) in the Republic of Georgia, a resource-poor country, and to determine antibiotic susceptibility of the isolated organisms.

METHODS

A cross-sectional study of all septic infants was conducted in the NICUs of two pediatric hospitals in Tbilisi between September 2003 and September 2004.

RESULTS

A total of 200 infants with clinical signs of sepsis were admitted to two NICUs. Of these, 126 (63%) had confirmed bacteremia. The mortality rate was 34%. A total of 98 (78%) of 126 recovered isolates were Gram-negative organisms and 28 (22%) were Gram-positive. Klebsiella pneumoniae was the most common pathogen, accounting for 36 (29%) of 126 isolates, followed by Enterobacter cloacae accounting for 19 (15%) and Staphylococcus aureus accounting for 15 (12%). The Gram-negative organisms showed a high degree of resistance to commonly used antibiotics such as ampicillin and amoxicillin/clavulanate, and comparatively low resistance to amikacin, ciprofloxacin, carbapenems, and gentamicin; 40% of S. aureus isolates were methicillin-resistant (MRSA). In multivariate analysis only umbilical discharge was a significant risk factor for having a positive blood culture at admission to NICU (prevalence ratio = 2.25, 95% confidence interval 1.82-2.77).

CONCLUSIONS

Neonatal BSI was mainly caused by Gram-negative organisms, which are developing resistance to commonly used antibiotics. Understanding the local epidemiology of neonatal BSI can lead to the development of better medical practices, especially more appropriate choices for empiric antibiotic therapy, and may contribute to improvement of infection control practices.

Important aspects of nosocomial bacterial resistance and its management

The article reviews management of nosocomial bacterial resistance aspects. Nosocomial infections are associated with substantial morbidity, mortality and cost. During the last several decades multi-drug resistant organisms increased in number considerably. Methicillin-resistant staphylococcus aureus, Vancomycin-intermediately resistant staphylococcus aureus and fully vancomycin-resistant staphylococcus aureus evolved as a consequence of methicillin and vancomycin use. The introduction of third generation cephalosporins were followed by emergence of extended spectrum and AMP-C -lactamases among gram negative bacteria, and carbapenems were targeted by carbapenemases. The poor diagnostic yield of current microbiologic methods in identifying certain resistant organisms, combined with decreasing numbers of newly developed antibiotics pose a significant challenge to physicians. We reviewed some of the approaches which can be followed to maximize the positive clinical outcome in patients with resistant nosocomial infections, using currently available antibiotics. More sensitive microbiological methods and new types of antibiotics are needed to adequately address the problem in the future.