Microbiological investigation of a hospital outbreak of invasive group A streptococcal disease in Krakow, Poland.

The present study reports the epidemiological investigations undertaken in one of Krakow's city hospitals regarding the source of infection and the routes of transmission of a group A streptococcus (Streptococcus pyogenes), using fluorescent in situ hybridization as a rapid method for detecting S. pyogenes carriage in the medical personnel involved. Four patients from the gynaecology department and two patients from the surgery department presented with clinical signs of infection. Characteristics of the S. pyogenes strains isolated from patients and from one medical staff member, including the emm gene and superantigens encoding genes, are described. All patients (four confirmed and two probable cases) survived; the operating theatre aid was identified as an S. pyogenes carrier and the source of the infections.

Epidemiology of invasive Streptococcus pyogenes infections in Germany, 1996-2002: results from a voluntary laboratory surveillance system.

A nationwide voluntary laboratory-based surveillance study of invasive Streptococcus pyogenes (group A streptococcus; GAS) infections was conducted in Germany between 1996 and 2002. Demographical and clinical information concerning the patients was obtained from the medical files. Multiple logistic regression analysis was used to determine risk-factors for fatal outcome. Invasive isolates were obtained from 475 patients, with 251 (52.8%) of the isolates cultured from blood. The most frequent emm types were emm1 (36.4%), emm28 (8.8%) and emm3 (8%). The speA, speC and ssa genes were present at variable frequencies in different emm types. The highest frequencies of speA and speC were found in emm1 (speA, 93.6%) and emm4 (speC, 94.7%), respectively. The estimated annual incidence of invasive GAS disease for 1997-2002 was 0.1 cases/100 000 individuals. This apparently low incidence rate might be explained by the voluntary nature of the surveillance system, resulting in relatively few cases being referred to the laboratory. Complete clinical information was available for 165 cases. The overall case fatality rate was 40.6%, and was highest (65.2%) in the group aged 60-69 years. Shock, an age of >or=30 years and adult respiratory distress syndrome were predictors of a fatal outcome in a multiple logistic regression analysis. Overall, 6.7% of the cases were considered to be nosocomial, and nine cases of puerperal sepsis were observed. The study underscores the importance of invasive S. pyogenes disease in Germany.

Periodic surveillance of nosocomial infections in a neurosurgery intensive care unit.

BACKGROUND: We assessed data on the epidemiology of nosocomial infections (NIs) in a 14-bed neurosurgical intensive care unit (NSICU) and used surveillance data for the promotion of quality improvement activities. PATIENTS AND METHODS: Prospective periodic surveillance was performed over five 3-month periods between July 1998 and October 2002 on all patients admitted with a length of stay > 24 hours. RESULTS: 763 patients with a total of 4,512 patient days and a mean length of stay of 5.9 days were enrolled within the 15-month study period. A total of 93 NIs were identified in 82 patients. Urinary tract infections (24.7%), pneumonia (23.6%), and bloodstream infections (17.2%) were the most frequent NIs recorded. Device-associated incidence rates were 6.0 (3.8-9.0, CI(95%)) for urinary tract infection, 4.4 (2.4-7.4, CI(95%)) for bloodstream infection, and 10.3 (6.3-15.9, CI(95%)) for pneumonia per 1,000 days at risk. For improvement of infection control-related processes, evidence-based infection control guidelines were established and an NSICU nurse was designated to be responsible for infection control issues on the ward. In addition, several infection control problems arose during the observation periods and were rapidly responded to by introducing specific intervention strategies. CONCLUSION: Periodic surveillance is a valuable tool for assessing the epidemiology of NIs in the NSICU setting as well as for promoting the initiation of quality improvement activities.

High-level fluoroquinolone resistance in a clinical Streptoccoccus pyogenes isolate in Germany.

An isolate of Streptococcus pyogenes isolated from a 63-year-old woman with a serious wound infection was found to be highly resistant to fluoroquinolones (levofloxacin MIC > or = 32 mg/L). DNA amplification and sequencing revealed a serine-81 to phenylalanine substitution in gyrA and three substitutions in parC: serine-79 to phenylalanine, aspartic acid-91 to asparagine, and serine-140 to proline. To our knowledge, this is the first report from a European country of a clinical isolate of S. pyogenes with high-level fluoroquinolone resistance.

Serum bactericidal activity of piperacillin/tazobactam against Staphylococcus aureus, piperacillin-susceptible and piperacillin-resistant Escherichia coli and Pseudomonas aeruginosa.

BACKGROUND: The serum bactericidal test measures the highest level of an antibiotic-containing serum dilution at which 99.9% of bacteria are killed. In this study the serum bactericidal activity of piperacillin/tazobactam was determined for bacteria often involved in severe infections. In earlier studies titres >/=1:8 in the serum bactericidal tests correlated well with clinical success in the treatment of endocarditis and osteomyelitis as well as bacterial eradication. METHODS: Blood samples of 6 healthy volunteers were taken before and 1 and 4 h after piperacillin/tazobactam (4.5 g) administration. Serum concentrations and serum bactericidal activity were determined for 10 strains each of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, both piperacillin-resistant and piperacillin-susceptible according to NCCLS guidelines. RESULTS: 100% of S. aureus and piperacillin-susceptible E. coli, 90% of piperacillin-resistant E. coli and 80% of P. aeruginosa were killed 1 h after drug administration. 4 h after drug administration serum bactericidal activity decreased to 60% for S. aureus, 90% for piperacillin-susceptible E. coli, 80% for piperacillin-resistant E. coli and 30% for P. aeruginosa. CONCLUSIONS: Excellent serum bactericidal activity of piperacillin/tazobactam was recorded 1 h after drug administration for S. aureus, E. coli and P. aeruginosa. After 4 h limited killing rates for P. aeruginosa could be detected, which supports the idea of a combination therapy.

Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment.

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (P<0.001). Gram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (P<0.001) and hospital personnel (P=0.1145). Environmental contamination did not differ between the intensive care units (ICUs) and the general wards (GWs), which is noteworthy because our ICUs are routinely disinfected twice a day, whereas GWs are cleaned just once a day with detergent. Current guidelines for the prevention of spread of multi-resistant bacteria in the hospital setting do not distinguish between Gram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources.

Inhibitor of complement, Compstatin, prevents polymer-mediated Mac-1 up-regulation of human neutrophils independent of biomaterial type tested.

The inflammatory reaction after cell contact with polymer materials is primarily mediated by activated neutrophils and may, in some cases, lead to exhaustion of neutrophil cell function. A direct consequence of this can be impairment of local or even systemic host defense mechanisms, which in turn can result in foreign body infections. Neutrophil activation, as indicated by the up-regulation of the Mac-1 adhesion receptor, is a reliable parameter for estimating the inflammatory risk due to implanted biomaterials. Because at blood contact, biomaterials immediately acquire a material-specific layer of blood proteins on their surface, including fibrinogen, complement, and immunoglobulin G, it is generally believed that after biomaterial contact, neutrophil activation primarily occurs by interaction with this protein layer. In this study, using our recently established polymer bead in vitro assay, we investigated whether complement inhibition alone can reduce biomaterial-mediated neutrophil activation, independent of the type of polymer and, hence, also its surface chemistry. Complement inhibition was achieved by using Compstatin, a recently developed complement inhibitor that binds to the complement component C3 preventing C3 convertase formation. We revealed significantly reduced (p < or = 0.025) Mac-1 receptor expression levels after 45 min of blood contact with the following polymers (without and with Compstatin): 1. polyurethane, 98.3%, 13.6%; 2. polymethylmetacrylate, 88.5%, 11.0%; and poly-D,L-lactide, 71.8%, 8.4%. Although these three polymer types acquire material-specific protein layers because of their different surface chemistry, complement inhibition by Compstatin alone proved to be sufficient to reduce neutrophil activation after surface contact, thus reducing the risk of biomaterial-mediated inflammatory reaction.

Comparison of the bactericidal activity of moxifloxacin and levofloxacin against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae.

In addition to MIC and MBC tests in this study the serum bactericidal activity of 3.1 microg/ml of moxifloxacin or 5.2 microg/ml of levofloxacin was determined against ten susceptible strains of S. aureus, S. epidermidis, E. coli and K. pneumoniae. Moxifloxacin achieved markedly better activity against S. aureus and S. epidermidis as compared to levofloxacin. Activity of moxifloxacin against E. coli and K. pneumoniae was excellent but not superior to levofloxacin. In conclusion both fluorquinolones are highly effective against E. coli and K. pneumoniae, moxifloxacin being superior with respect to gram-positives like S. aureus and S. epidermidis.

Simultaneous measurement of biopolymer-mediated Mac-1 up-regulation and adherence of neutrophils: a novel flow cytometric approach for predicting initial inflammatory interaction with foreign materials.

Implantation of any medical device normally causes an inflammatory cell interaction with the foreign material. In vitro cell activation of human neutrophils (Mac-1 upregulation) has been taken as one measure to assess the attributable risk of inflammation due to biopolymers before their clinical application. Mac-1 expression has generally been measured by flow cytometric assays, whereas quantification of neutrophil adhesion to the biopolymer surfaces has been performed by separate and time-consuming assays, e.g. microscopically by differential cell counting. However, due to an increasing number of surface-modified novel biopolymers entering clinical usage, effective testing of their inflammatory potential is now mandatory. To facilitate these analyses, we have developed a novel flow cytometric assay permitting simultaneous measurement of biopolymer-mediated neutrophil activation and adhesion. The biopolymers were used as beads (diameter 25+/-10 microm), and were demonstrated to be non-phagocytosable and non-fluorescent before being co-incubated with whole human blood (range of ratio granulocytes/beads from 5:1 to 1:1). Besides flow cytometric measurement of Mac-1 up-regulated neutrophils as fluorescing events, a fluorescence of the bead population indicates the adherence of activated neutrophils to the biopolymer surface.After establishing this assay, we evaluated it by comparing six different biopolymers. We observed high levels of Mac-1 expression (>70% of positive control) accompanied by increased adhesiveness (>60% of neutrophils) for polyurethane (PUR), polymethylmetacrylate (PMMA), and poly-DL-lactide (PDLLA) beads. Low Mac-1 expression levels (<10%) accompanied by a low percentage of adhering neutrophils (<10%) were observed for polyethylene (PE), polyisoprene (PI), and silicone (SI) beads.

Horizontal gene transfer and host specificity of beta-haemolytic streptococci: the role of a putative composite transposon containing scpB and lmb.

Beta-haemolytic streptococci are important human and animal pathogens: their genetic traits that are associated with the ability to infect human hosts remain, however, unclear. The surface protein, Lmb, mediates the adherence of Streptococcus agalactiae to human laminin. For further analysis of the corresponding gene, the adjacent genomic regions were sequenced. Lmb is localized on a putative composite transposon of 16 kb and is flanked by two copies of a novel insertion sequence element (ISSag2). It harbours the genes scpB and lmb, which are 98% identical with the respective genes of Streptococcus pyogenes. Analysis of the distribution of these genes and ISSag2 among 131 streptococcal strains revealed that all of the human isolates, but only 20% (12 of 61) of the animal isolates, contained scpB and lmb or their homologues. To investigate if the putative transposon can be mobilized, an erythromycin resistance marker was incorporated into the lmb gene of S. agalactiae. Screening for mutant strains with a regained susceptibility for erythromycin identified strains with a deletion of scpB, lmb, and one copy of ISSag2. We hypothesize that a horizontal gene transfer caused the exchange of scpB and lmb and that the ability of S. pyogenes, S. agalactiae and group C and G streptococcal strains to colonize or infect human hosts is dependent on their presence.

In vitro activity of cefditoren against clinical isolates of penicillin-susceptible and penicillin-intermediate strains of Streptococcus pneumoniae isolated in Germany, 1992-1998.

This study investigates the susceptibility to cefditoren of penicillin-susceptible strains of invasive Streptococcus pneumoniae (n = 312) and of penicillin-intermediate strains of S. pneumoniae (n = 30) isolated mainly from patients with respiratory tract infections. The MIC(90)s of penicillin-susceptible and -intermediate isolates were as follows: cefditoren, < or =0.06 and 1 mg/L; penicillin G, < or =0.06 and 0.5 mg/L. Cefditoren showed the highest activity against the penicillin-intermediate strains investigated compared with the other beta-lactam antibiotics and is therefore considered to be a promising agent for the treatment of infections caused by pneumococci with reduced penicillin susceptibility.

Typing of Streptococcus pyogenes strains isolated from throat infections in the region of Aachen, Germany.

BACKGROUND: Changes in the epidemiology of Streptococcus pyogenes infections may be associated with the introduction and reappearance of individual serotypes within a population. MATERIALS AND METHODS: Typing of 216 consecutive isolates of S. pyogenes from patients with pharyngitis in the region of Aachen, Germany, was performed by sequencing the emm gene, slide-agglutination of the T-antigen and determining the serum opacity reaction (SOR). RESULTS: All 216 isolates were unequivocally emm-typable. emm1 was most common (18.5%), foLlowed by emm12 (15.7%), emm3 (14.4%) and emm28 (13.9%). Only four isolates contained newly validated emm types: emm89 or emm94 were harbored by two isolates each. In one isolate, the sequence type s104 was found. CONCLUSION: Despite an anticipated selective pressure, the prevalence of emm1 among isolates from throat infections in northwestern Germany remains high, but does not reflect the predominance of emm1 among invasive isolates in Germany.

Macrolide resistance in Streptococcus pyogenes isolates from throat infections in the region of Aachen, Germany.

Macrolide-resistance was assessed in 216 consecutive Streptococcus pyogenes isolates from throat infections in the region of Aachen, Germany. Seventeen isolates were resistant to erythromycin: 12 isolates revealed a macrolide (M) phenotype and harbored mefA, and five strains expressed an inducible macrolide-lincosamide-streptogramin B (MLSB) phenotype of which four strains harbored ermA(TR) and one strain contained ermB(AM). Telithromycin (HMR 3647) and quinupristin/dalfopristin remained active particularly against the ermA(TR)-containing S. pyogenes isolates studied. Random amplified polymorphic DNA analysis identified multiple clones among erythromycin-resistant strains, but did not discriminate beyond the emm-type. mefA was present in three isolates either with emm2, emm12, or emm75, and in nine isolates with emm4. All four strains with ermA(TR) contained emm77, and the single strain with ermB(AM) harbored emm1. Despite the relative low rate of macrolide-resistance, these data suggest that at least three different macrolide-resistance determinants are prevalent in Germany and that mefA has spread rapidly into multiple clones of S. pyogenes.

Implementing and evaluating a rotating surveillance system and infection control guidelines in 4 intensive care units.

BACKGROUND: In clinical practice, scientific evidence about infection control is often ignored and hygiene rituals are followed. METHODS: Within an evidence-based infection control program, a quarterly rotating surveillance program for nosocomial infections was implemented in 4 intensive care units (ICUs) at the Aachen University Hospital, Germany. RESULTS: For the first time, the unit-specific nosocomial infection situation was made clear to the clinical staff by interpretive feedback of the surveillance data. This led to an increased awareness of infection control and a critical review of hygiene practices. After the first surveillance period, the hygiene practices of each ICU were revised and modified. The Centers for Disease Control and Prevention/Hospital Infection Control Practices Advisory Committee guidelines for the prevention of nosocomial infections were adopted and established in tight collaboration with the ward staff. CONCLUSIONS: Within the surveillance process, communication and team spirit between infection control and patient care personnel showed a remarkable improvement. Awareness and compliance with hospital hygiene and infection control practices could be raised without directive interaction.

Increased titers of antibodies against streptococcal M12 and M19 proteins in patients with Tourette's syndrome.

It has been suggested that a post-streptococcal autoimmune process may be involved in the pathogenesis of a subgroup of children with tics and obsessive-compulsive symptoms (PANDAS). Elevated antibody titers against streptococcal antigens have also been described in adult patients suffering from Tourette's syndrome (TS). In order to characterise further streptococcal antigens, we focussed on M proteins. M proteins are a major virulence factor of group A streptococci and known to evoke an immunologic cross-reaction with diverse epitopes of human tissue including brain tissue. Therefore, antibodies against M proteins may play a role in the pathophysiology of at least a subgroup of TS patients. Antibodies against M proteins were studied in 25 adult patients suffering from TS and 25 healthy controls after careful medical examination. The antibody titers against the peptides M1, M4, M6, M12 and M19 were estimated by ELISA. Our results show increased titers of antibodies against the streptococcal M12 and M19 proteins in TS patients as compared with controls, while antibody titers against M1, M4 and M6 did not differ between the TS and control groups. Elevated serum titers of antibodies against M12 and M19 proteins support the view that a streptococcus-induced autoimmune process may be involved in TS. The finding of a possible autoimmune origin of TS has implications for both pathophysiology and future therapeutic strategies.

Nationwide German multicenter study on the prevalence of antibiotic resistance in streptococcal blood isolates from neutropenic patients and comparative in vitro activities of quinupristin-dalfopristin and eight other antimicrobials.

In a prospective multicenter study (1996 to 1999), 156 episodes of bacteremic streptococcal infections of neutropenic patients were evaluated. Streptococcus oralis (26.3%), S. pneumoniae (26.3%), S. agalactiae (11.5%), S. mitis (9%), and S. pyogenes (5.8%) were the predominant species. Four strains (2.6%) were found to be intermediately resistant to penicillin. One strain (0.6%) was found to be highly resistant to penicillin (MIC, 8 mg/liter). Reduced susceptibility to penicillin was detected among S. oralis (14.6%), S. mitis (7.1%), and S. pneumoniae (4.9%) isolates but was not recorded among S. agalactiae and S. pyogenes. Resistance rates and intermediate resistance rates for other antimicrobials were as follows (all species): amoxicillin, 1.3 and 3.2%; erythromycin, 16 and 2.6%; clindamycin, 5.8 and 0%; ciprofloxacin, 1.9 and 7.7%. Quinupristin-dalfopristin showed good in vitro activity against most streptococcal isolates (MIC at which 50% of the isolates were inhibited [MIC(50)], 0.5 mg/liter; MIC(90), 1 mg/liter, MIC range, 0.25 to 4 mg/liter).

Antimicrobial resistance of Streptococcus pneumoniae recovered from outpatients with respiratory tract infections in Germany from 1998 to 1999: results of a national surveillance study.

Clinically significant pneumococcal isolates were prospectively collected from outpatients with respiratory tract infections by 19 different clinical microbiology laboratories in Germany. Resistance rates in a total of 961 isolates were as follows: penicillin, 6.6%; clarithromycin, 10.6%; tetracycline, 13.9%; and levofloxacin, 0.1%. Among 324 isolates from children, pneumococcal serotypes 19F (17.0%), 23F (13.0%), and 6B (11.7%) were the predominant types.

Comparison of two sampling methods for the detection of gram-positive and gram-negative bacteria in the environment: moistened swabs versus Rodac plates.

The objective of this study was to evaluate the moistened swab technique vs. Rodac plates for detecting Gram-positive and Gram-negative bacteria in the inanimate environment. Over a period of 22 months, the environment of 190 patients infected or colonized with MRSA, VRE or multiresistant Gram-negative bacteria was sampled in turn. MRSA and VRE could be detected with either method in 33 out of 54 (61.1%) patient rooms in 174 out of 706 (24.6%) environmental samples. However, multiresistant Gram-negative bacteria were found in 42 out of 136 (30.9%) rooms with a very low frequency of 89 out of 1827 (4.9%) environmental samples (p < 0.0001). The sensitivity of the swab technique for Gram-positive cocci was 54% (94/174) vs. 69.5% (121/174) for the Rodac plates, ([CI95%], 47-61% vs. 62-76%, p < 0.05). In contrast, the sensitivity of the swab technique for Gram-negative bacteria was 74.2% (66/89) vs. 42.7% (38/89) for the Rodac plates, ([CI95%], 64-83% vs. 32-54%, p < 0.05). In conclusion, environmental contamination with Gram positive cocci is detected more often than with Gram-negative bacteria. For the detection of Gram-positive cocci, Rodac plates are superior to the swab technique; whereas Gram-negative rods can be detected more often by the swab technique. All these results proved to be statistically significant.

Assessment of acid production by various human oral micro-organisms when palatinose or leucrose is utilized.

One promising way of reducing caries is by using sucrose substitutes in food, e.g., palatinose or leucrose. Previous experiments addressing cariogenic potential of sucrose substitutes have focused mainly on Streptococcus mutans. However, given the many other micro-organisms in the oral cavity, this study compared the acid production of 100 bacterial strains representing 44 different species, by batch fermentation in a test tube containing, as a sole carbohydrate source, glucose, sucrose, palatinose, or leucrose. Selected strains were further analyzed in a fermenter. Additionally, 30 yeast strains were tested by an auxanographic sugar assimilation test. Only Lactobacillus spp., Stomatococcus mucilaginosus, Leuconostoc mesenteroides, and Weissella paramesenteroides, and some of the yeasts studied-i.e., Candida albicans, C. tropicalis, C. parapsilosis, and Saccharomyces cerevisiae-utilized leucrose and/or palatinose well. Strikingly, Stomatococcus mucilaginosus produced water-insoluble polysaccharides by fermentation of leucrose and palatinose. In the fermenter, the respective sucrose substitutes were not only cleaved but also utilized. Thus, extracellular cleavage by autochthonous micro-organisms may produce cariogenic cleavage products (glucose, fructose) that can be used by other well-characterized cariogenic bacteria found in the oral flora. Therefore, the anticariogenic potential of sucrose substitutes in food might be limited.