Diseases and pathogenes


Human Bacterial Pathogens

I.V. Smirnov

Ryazan State Medical University named under I.P.Pavlov

Extension of spectrum of human bacterial pathogens as well as variety of their characteristics and unequal medical significance demand further study in order to extend the information on bacterial infections. This knowledge is necessary for organization of prudent tactics in the treatment of classical and opportunistic infections especially at the initial (pre-laboratory) and final (interpretation) microbiological diagnostic stages as well as for selection of means for etiological treatment and specific prophylaxis. Thus it seems very important for physicians and other medical staff to be aware of particular features of human bacterial pathogens and their classification.

The material presented includes the data on systemic position of human bacterial pathogens, their virulence and gives a practical approach to diagnostics, treatment and prophylaxis of bacterial infections.

Key words: bacteria, infections, classification, taxonomy.

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Prions and prion diseases

I.A. Zavalishin, I.E. Schitikova, T.D. Zhuchenko

Institute of Neurology RAMS, Moscow

Prion diseases belong to the group of neurodegenerative diseases that are very rare in general population and are registered as sporadic, infectious and inherited forms. These diseases are caused by contagious prion protein that appears as the result of conformational changes of normal host protein on posttranslational stage. There is phenotypical heterogenesis of prion diseases is the result of interreaction of several factors. The most important of them seems to be the expression of the protein PrPres and polymorphism in codon 129. Lifetime diagnosis of prion diseases is insufficient and there is no reliable options for treatment of these disease as well as for specific prophylaxis.

Key words: prion, Creutzfeldt-Jakob disease, Gerstmann-Streussler-Scheinker syndrome, fatal familial insomnia, kuru.

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Listeriae: the role in infectious diseases and laboratory diagnostics

I.S. Tartakovski

Institute of Epidemiology and Microbiology named under N.F. Gamaleya, RAMS

Current approaches covering the role of listreriae in infectious diseases for more than 70 years are given in this article. The main factors causing evident upgrowth of morbidity are analysed. The most prominent of them are: contamination and active reproduction of listeriae in food products, increase of susceptibility in risk groups due to abnormality cellular immunity. Intracellular parasitism features and distinctions of listeriae pathogenity are examined. The analysis of various methodical approaches to diagnosis of listeriosis shows the leading role of bacteriological methods of L.monocytogenes isolation and identification that are based on usage of selective media. The introduction of these methods into the work of laboratories and epidemiology surveillance centers is strongly advisable.

Keywords: listeriae, epidemiology, pathogenity, microbiological diagnosis

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Antibacterial Therapy of Infective Endocarditis

V.P. Tjurin, I.G. Tichonov

Main Military hospital named under N.N. Burdenko, Moscow.

Infective endocarditis (IE) is a life-threatening infection that is invariably lethal without intensive antibacterial treatment. Wide array of microorganisms has been encountered as causative agents of infection with streptococci (viridans streptococci) and staphylococci being the most common. Other bacteria, fungi, chlamydiae, rickettsiae, etc. are less frequently responsible for IE. The cornerstone of successful therapy is a prolonged parenteral treatment with high doses of appropriate bactericidal antibiotics. We review published recommendations for antimicrobial treatment of IE caused by specific microorganisms depending on their antibiotic susceptibility and empiric antibacterial treatment of IE with unknown etiology as well. Short regimens of antibiotic therapy will be also discussed.

Key words: Infective endocarditis, antibacterial treatment.

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Urinary Tract Infections in Patients with Diabetes Mellitus

A. I.M. Hoepelman, S.E. Geerlings

Department of Medicine, Division Infectious Diseases & AIDS
Eijkman-Winkler Institute University Medical Center, Utrecht, Netherlands

Urinary tract infections (UTI) are second only to respiratory tract infections as problems encountered by practicing physicians. They occur most often in young healthy adult women and are easy treatable in these patients. However, in some patient groups infections occur more often, can have a complicated course, are more difficult to treat and often recur. Many of them have easily recognisable urological abnormalities, but also more subtle conditions as age over 65 years, treatment with immunosuppressive drugs, HIV-infection with a CD4+ count below 200/mm3 and last but not least diabetes mellitus lead to an enhanced susceptibility for UTI. Besides organ complications as retinopathy, nephropathy and neuropathy, infections are common problems in these patients. UTI complications (e.g., bacteremia, renal abscesses, and renal papillary necrosis) occur more often in diabetic patients.

We recently have completed a study in 636 non-pregnant women with DM (in- and outpatients and diabetics visiting their GP). The prevalence of asymptomatic bacteriuria was 26% compared to 6% in the control group (p<0,001). The prevalence of asymptomatic bacteriuria in the 378 women with DM type 2 was 29% (compared to 21% in those with DM type I). Therefore, the prevalence of asymptomatic bacteriuria is consistently higher in diabetic women than in non-diabetics. In the study mentioned above risk factors for asymptomatic bacteriuria in all women with DM were retinopathy, macroalbuminuria, a longer duration of the diabetes, a lower body mass index, and a symptomatic UTI in the previous year (p<0,05). Risk factors for asymptomatic bacteriuria in the women with type I diabetes included a longer duration of the diabetes, peripheral neuropathy, and macroalbuminuria. The prevalence of asymptomatic bacteriuria was 29% in women with DM type II. Risk factors in these women included age, macroalbuminuria, a lower body mass index, and a UTI in the previous year. All p-va-lues were adjusted for age. There was no association between the diabetes regulation and the presence of a post-voiding bladder residue and the presence of asymptomatic bacteriuria. We followed the cohort mentioned before for 18 months. Of these 589 women, 115 (20%) developed a symptomatic UTI. Women with DM type II and asymptomatic bacteriuria at baseline had an increased risk of developing UTI, compared to women with DM type II without asymptomatic bacteriuria at baseline (p=0,005). There was no difference in the incidence of a symptomatic UTI between DM type I women with and those without asymptomatic bacteriuria. DM type I women with asymptomatic bacteriuria had tendency to a faster decline in renal function than those without asymptomatic bacteriuria (4,6 versus 1,5%, p=0,02).

Studies demonstrate greater susceptibility of diabetic than of nondiabetic animals to urinary tract infection. Suggested mechanisms are: decreased antibacterial activity due to the "sweet urine", defects in neutrophil function, increased adherence to uroepithelial cells. We have shown that bacteria indeed grow better in urine with glucose, however, very high concentrations inhibit growth and in the clinical study no effect of regulation of DM was documented. We also have shown that no difference exist in PMN function between diabetic women with/without and controls. However, Escherichia coli expressing type I fimbriae adhere better to uroepithelial cells of diabetic women.

Key words: urinary tract infections, diabetes mellitus, asymptomatic bacteriuria.

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The Economic Impact of Staphylococcus aureus Infection

Robert J. Rubin, Catherine A. Harrington, Anna Poon, Kimberly Dietrich, Jeremy A. Greene, Adil Moiduddin

The Lewin Group, Fairfax, Virginia, USA

Translated and reprinted with permission from «Emerging Infectious Diseases» 1999;5:9-17

We modeled estimates of the incidence, deaths, and direct medical costs of Staphylococcus aureus infections in hospitalized patients in the New York City metropolitan area in 1995 by using hospital discharge data collected by the New York State Department of Health and standard sources for the costs of health care. We also examined the relative impact of methicillin-resistant versus-sensitive strains of S.aureus and of community-acquired versus nosocomial infections. S.aureus-associated hospitalizations resulted in approximately twice the length of stay, deaths, and medical costs of typical hospitalizations; methicillin-resistant and -sensitive infections had similar direct medical costs, but resistant infections caused more deaths (21 versus 8%). Community-acquired and nosocomial infections had similar death rates, but community-acquired infections appeared to have increased medical costs per patient ($35 300 versus $28 800). The results of our study indicate that reducing the incidence of methicillin-resistant and -sensitive nosocomial infections would reduce of S.aureus infection.

Key words: infections, Staphylococcus aureus, pharmacoeconomics.

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Antimicrobial Resistance



Antimicrobial Resistence of Shigellae in Smolensk Region during 1998-1999

L.S. Stratshunski*, O.I. Kretcikova**, A.S. Ivanov*, M.M. Suvorov*, M.V.Sukhorukova**

* Institute of Antimicrobial Chemotherapy, Smolensk State Medical Academy

** Smolensk Regional Centers of Sanitary and Epidemiological Surveillonee

The purpose of the study – to determine the antimicrobial resistance of Shigella sonnei and Shigella flexneri isolated in Smolensk Region and to develop recommendations for empiric therapy of shigellosis. A total of 88 strains of S.flexneri and 69 strains of S.sonnei isolated in Smolensk and Smolensk Region during 1998–1999, were tested to 9 antimicrobials: ampicillin (AM), ampicillin/sulbactam (AMS), cefotaxime (CTX), tetracycline (TE), chloramphenicol (CL), nalidixic acid (NLA), norfloxacin (NOR), ciprofloxacin (CIP), trimethoprim/sulfamethoxazole (SXT) by agar dilution method.

High rates of resistance were found in both S.flexneri and S.sonnei, to: SXT (96,6 and 94,2% respectively), TE (97,7 and 92,8% respectively), CL (93,2 and 50,7% respectively), AM (95,5% and 26,1% respectively) and AMS (95,5 and 23,2%). No resistance to NLA, NOR, CIP and CTX was detected. High rates of multiresistance (defined as resistance to 3 and more antimicrobials) was found: 96,9 and 63,8% in S.flexneri and in S.sonnei, respectively. Among S.flexneri 87,5% of strains were characterized by the AM/AMS/CL/TE/SXT phenotype of resistance and 37,7% of S.sonnei strains had SXT/CL/TE one.

CL, TE and SXT lost his efficacy against Shigella spp. and can not be recommended for the empirical therapy of shigellosis in Smolensk Region. Quinolones and cephalosporins III remain highly active and can serve as drugs of choice for the treatment of shigellosis.

Key words: shigellosis, Shigella, antimicrobial resistance.

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Laboratory Diagnostics



Post-mortem Microbiological Analysis and Interpretation of Its Results

M.A. Seredkina, O.I. Kretchikova, M.V. Suchorukhova

Smolensk Regional Centres of Sanitary and Epidemiological Surveillance

This review summarises the data given in medical literature and presents an attempt to elucidate the problems of post-mortem specimens analysis from microbiological point of view. It includes general recommendations for specimen collection, processing and interpretation of the microbiology results that may be useful for pathologists as well as for microbiologists. The necessity of post-mortem microbiological analysis is considered, taking into consideration pathologoanatomic examination and laboratory equipment.

Key words: microbiological analysis, post-mortem cultures, autopsy, pathologoanatomic examination, interpretation of results.

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Guidelines for clinicians



Dosage of antibiotics in patients with renal impairment

L.S. Stratchounski, N.N. Sudilovskaja, A.N. Schevelev

Institute of Antimicrobial Chemotherapy, Smolensk State Medical Academy

Most drugs and their metabolites are partly or completely excreted by kidneys. Thus in patients with renal impairment it is often crucial to modify antibiotic dosage regimens accordingly to the renal function tests. One of the main characteristics is glomerular filtration rate that can be estimated on the base of creatinine clearance. This article provides the guidelines for dose and regimen adjustment of the most frequently prescribing antibiotics. Principles of antibiotic usage in patients on haemo- and peritoneal dialysis are also discussed.

Key words: antimicrobials, renal impairment, renal function, haemodialysis, peritoneal dialysis.

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Guidelines for microbiologists



Isolation, identification and antimicrobial susceptibility testing of Haemophilus influenzae

These guidelines are focused on the one of the most frequent bacterial pathogen causing community-acquired infections – Haemophilus influenzae. Collection of clinical specimens, selective and non-selective media for isolation, morphological and phenotypic approaches to identification are described in details. Advantages and disadvantages of different susceptibility testing methods are highlighted. Criteria for interpretation of results based on international guidelines (NCCLS) are presented.

These guidelines are designed for microbiologists, epidemiologists, and laboratory assistants.

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