Bacteriological study of otogenic cerebral abscesses: chemotherapeutic role of metronidazole.

In nine consecutive patients with otogenic cerebral abscesses a mixed growth of aerobic and obligate anaerobic bacteria was isolated from the pus in five patients, and in the remaining four obligate anaerobes were the sole isolates. The commonest obligate anaerobe isolated was Bacteroides fragilis, which was present in all but one patient. The patients were all treated with metronidazole for the anaerobic organisms and with appropriate chemotherapy against the aerobic organisms isolated. All the patients recovered and only one was left with a neurological deficit. As otogenic cerebral abscesses constitute a major proportion of all cerebral abscesses, the use of metronidazole against obligate anaerobic bacteria, which tend to dominate in such abscesses, should reduce the high mortality from this condition.     

Clinical Importance of Infections due to Bacteroides fragilis and Role of Antibiotic Therapy

Out of 200 infections due to Bacteroides fragilis occurring over a period of three years 133 were related to the intestinal tract, 55 to the genitourinary tract, and the remainder were in bedsores and ulcers; 56% occurred in patients undergoing major intestinal surgery.B. fragilis was isolated in pure culture from 56% of the infections. In mixed culture it was most commonly associated with Klebsiella and Enterobacter species. Other anaerobic bacteria were isolated in 9% of the mixed cultures.Altogether 131 (65·5%) of the patients recovered without antibiotic therapy or further surgery, but 59 (29·5%) developed complications and 10 (5%) died. The commonest complication was abscess formation, and the incidence was highest with infections associated with malignancy (44%) and lowest with obstetric infections (5%). The mortality was 5% overall but in the presence of bacteraemia it rose to 33%.Only 43 patients received appropriate chemotherapy. Clindamycin was the most effective antibiotic, having a recovery rate of 78%, but this rate was little better than in untreated patients (65%). The role of prophylactic antibiotic therapy in preventing bacteroides infection remains to be studied.The incidence of the isolation of bacteroides from wound infections after major intestinal surgery rose from 13% in 1970 to 81% in 1973. This increase was due to both the accurate collection and care of specimens while in transit to the laboratory and the use of selective media for the isolation of bacteroides in laboratory culture. The importance of these precautions is emphasized.     

Isolation of Propionibacterium acnes from central nervous system infections

Propionibacterium acnes is a common skin colonizer and its involvement in central nervous system (CNS) infections may be related with previous neurosurgical procedures. P. acnes was isolated in pure or mixed cultures from ten patients with CNS infections during a 5-year period. The clinical presentation, treatment and outcome were retrospectively reviewed. Nine out of 11 patients had CNS infections after a neurosurgical procedure. The clinical presentation was: brain abscess (five patients), subdural or epidural empyema (four patients) and shunt meningitis (one patient). Three patients had also secondary meningitis. All patients received antibiotic therapy and all abscesses and empyemas were drained. The patient with shunt meningitis cured without catheter removal. Only one patient with a brain abscess by P. acnes died, but several months thereafter and as a consequence of a Gram-negative superinfection. P. acnes is a pathogen for the CNS and infections must be surgically managed under adequate antibiotic treatment.     

Co-culture of Bifidobacterium adolescentis and Bacteroides thetaiotaomicron in arabinogalactan-limited chemostats: effects of dilution rate and pH

The effects of dilution rate (D = 0.04-0.38/h) and pH (5.0-6.5) on co-cultures of Bifidobacterium adolescentis and Bacteroides thetaiotaomicron were studied in arabinogalactan-limited chemostats. B. thetaiotaomicron outcompeted B. adolescentis at all dilution rates at culture pH values between 5.0 and 6.0, although the bifidobacterium was always detected in the fermenters. At pH 6.5, however, B. adolescentis predominated in co-cultures at dilution rates above 0.24/h. Arabinogalactan degrading enzymes (beta-galactosidase, alpha-arabinofuranosidase) were strongly catabolite repressed in bacteroides at high dilution rates, but were constitutive and growth rate-associated in B. adolescentis. The increased competitiveness of B. adolescentis at high specific growth rates was not related to its ability to synthesise increased levels of depolymerising enzymes. Measurements of residual carbohydrate in pure and mixed culture chemostats showed that the bacteroides extensively digested the galactose backbone of the polymer, and to a lesser degree, the arabinose sidechains. Nevertheless, arabinose monomers and oligosaccharides (d.p. < 10) accumulated in these cultures under all growth conditions. In contrast, the bifidobacterium utilized considerably less arabinogalactan than the bacteroides, and this was reflected in the mixed culture studies. These experiments demonstrate that B. thetaiotaomicron was able to compete most successfully for this plant cell wall polysaccharide under nutritional, physiological and environmental conditions broadly similar to those encountered in the human colon, and indicate the existence of synergistic interactions between the two organisms that were growth rate dependent.     

Successful antimicrobial therapy of hepatic,intra-abdominal and intrapelvic abscesses.

Antimicrobial therapy without surgical drainage or therapeutic aspiration was effective in the management of four patients with deep abscesses ranging in diameter from 1.3 to 10.0 cm. Two of the patients had multiple hepatic abscesses, one had hepatic, intra-abdominal and intrapelvic abscesses, and one had an intrapelvic abscess alone. Anaerobic bacteria were isolated from the blood or abscesses in all four patients, and an aerobic-anaerobic infection was present in one patient. The patients were treated with metronidazole, alone or in combination with other antibiotics, for 3 to 6 weeks. Therefore, in selected patients with deep abscesses, a therapeutic trial of antimicrobial agents instead of surgery may be justified.     

Antimicrobial susceptibilities of Coagulase-Negative Staphylococci (CNS) and Streptococci from bovine subclinical mastitis cases

The prevalence and antimicrobial susceptibilities of Staphylococci and Streptococci were assessed from subclinical mastitis cases. One hundred Coagulase-Negative Staphylococci (CNS) and 34 Streptoccocci were identified. The most frequently isolated species were Staphylococcus haemolyticus (27%) and Staphylococcus simulans (24%). Susceptible CNS species revealed the highest resistance to penicillin G (58%), ampicillin (48%), neomycin (20%), and oleandomycin (14%). CNS methicillin resistance rates within 82 isolates were 21.95% and 1.22% by disk diffusion and PCR methods, respectively. These results suggested the disk diffusion method was more prone to yield false positives. Partial sequencing of the 16S rRNA region from the mecA carrying isolate (S. haemolyticus) was homologous with S. haemolyticus sequences/accessions obtained from GenBank. However, the mecA gene sequence from this isolate was more closely allied with the S. aureus mecA gene of human origins. Identical sequence data was acquired from the National Center for Biotechnology Information (NCBI) database, suggesting horizontal gene transfer between the two species. CNS β-lactamase activity within 81 isolates was 29.63%. The most frequently isolated Streptococcus species were S. uberis (52%) and S. agalactiae (15%). Oleandomycin was the least effective antimicrobial agent on these isolates with 59% susceptibility. Results indicated that CNS and Streptococci exhibited various antimicrobial resistance responses. Consequently, isolation and identification of udder pathogens in herds suffering from subclinical agents is essential to select the most effective antimicrobial agent. Moreover, multiple resistance features of methicillin resistant (MR) isolates should be considered during antimicrobial susceptibility tests.     

Bacterial Spoilage of Thawed Frozen Peas

The main groups of bacteria developing in peas were isolated on differential media. Leuconostoc mesenteroides and Streptococcus lactis predominated and smaller numbers of catalase positive 'coryneform'bacteria were also regularly present. Strep. cremoris , streptococci (group D), catalase positive cocci and Gram negative rods were less regularly isolated.
Bacterial spoilage of untreated peas was usually accompanied by the development of a yellow colour and a reduction in pH. In pure culture in peas leuconostocs and group N streptococci produced an acid pH while the catalase positive organisms produced alkali, sometimes with ammoniacal odours. In mixed cultures in peas the products of a leuconostoc and a 'coryneform'tended to neutralize each other. A leuconostoc and a 'coryneform'did not interfere with each others'growth when grown from similar inocula. The behaviour of streptococci is still being investigated. The type and rate of spoilage probably depends on the balance between ammonia production and acid production in the system.     

Characteristics of the antibiotic sensitivity of nitrofuran--resistant Gram-negative bacteria of clinical origin]

494 persons with various purulent inflammatory diseases were examined. Gram-negative nitrofuran resistant organisms isolated from the clinical material were found in 22.9 per cent of the cases. Representatives of Enterobacteriaceae, Klebsiella-Enterobacter-Serratia (26.8 per cent), Proteus-Providencia (16.8 per cent) and E. coli-Arizona-Citrobacter (16.1 per cent) predominated. Pseudomonas (32.1 per cent) and Acinetobacter (5.3 per cent) predominated among the aerobic gram-negative bacteria. Sensitivity of 131 strains to 10 chemotherapeutic drugs was determined. 60.4 per cent of the aerobic and 44.2 per cent of the Coli bacteria had multiple drug resistance (to 5 and more drugs). The organisms isolated from the urine and wound excretion were most resistant. Representatives of Pseudomonas and Klebsiella-Enterobacter predominated among the polyresistant cultures. High sensitivity of the isolates to gentamicin, carbenicillin and nalidixic acid was noted.     

Inhibition of Shigella flexneri by the Normal Intestinal Flora II. Mechanisms of Inhibition by Coliform Organisms

Of 15 strains of coliform bacteria, all isolated from human feces, 14 inhibited the growth of Shigella flexneri in mixed culture. In every case, when inhibition occurred, exponential growth of Shigella was interrupted in the mixed culture and the organisms entered into either a stationary or a death phase. None of the test coliform strains produced colicines active against Shigella. An analysis of mixed-culture environments at the time Shigella inhibition occurred revealed that the inhibition was not due to nutrient depletion nor to the development of adverse pH or oxidation-reduction potentials in themselves. In mixed cultures, the coliform strains produced formic and acetic acids in concentrations that inhibited Shigella growth. With one exception, the coliform strains also greatly reduced the culture medium. In average concentrations produced, the formic and acetic acids exerted a bactericidal effect on Shigella under the reduced conditions found in mixed cultures. The acids were only moderately toxic for the coliform strains under the same conditions. Results indicate that volatile acid production and concomitant reduction of the medium are the mechanisms by which coliform bacteria inhibit Shigella growth in mixed cultures.     

Pyogenic cocci in infantile eczema throughout one year.

To determine the source of pyococci causing attacks of sepsis in infantile eczema 20 patients with continuing eczema were followed up for one year, regular swabs being taken from the skin, nose, throat, and family contacts. The staphylococci were phage typed and the streptococci serologically typed. Staphylococci of the same phage type in most cases remained in reservoir sites on the skin and coincidently in the nose. Staphylococci causing attacks of clinical sepsis arose from these persistently colonized sites. Staphylococci of the same phage type were also common in family contacts. Streptococci of the same group in most cases did not remain on the skin. Streptococci causing attacks of clinical sepsis arose as new infections from external sources, sometimes from throat infections in the patient or family contacts. Strains of streptococci which are known to be associated with glomerulonephritis were isolated. It has been confirmed that staphylococci resistant to neomycin and sodium fusidate quickly emerge after the topical use of these antibiotics. Streptococci are highly resistant to neomycin and gentamicin, and moderately resistant to sodium fusidate, so the use of these antibiotics in topical steroid preparations will have little effect in preventing further attacks of clinical sepsis in these patients.     

Microbiology of pyogenic liver abscess.

Sixteen patients with pyogenic liver abscesses were studied over 10 years to discover the causative organisms of the condition. Pus was subjected to Gram-negative smear or gas-liquid chromatography to detect volatile acids characteristic of anaerobes and then cultured. All isolates were identified by conventional methods and tested for sensitivity to appropriate antimicrobial agents. Bacteria were grown from the liver abscesses in all 16 patients. Streptococcus milleri Lancefield group F was the commonest organism isolated from the pyogenic liver abscesses, being found in 13 patients. If Strep milleri is isolated care should be taken not to mistake it for an anaerobe, and finding the organism in the blood should alert the clinician to the possible presence of a liver abscesses.     

Characterization of the bacterial microflora of the tympanic cavity of eastern box turtles with and without aural abscesses

Aerobic bacterial cultures of the tympanic cavity of the middle ear were performed in eight eastern box turtles (Terrapene carolina carolina) with aural abscesses and 15 eastern box turtles without aural abscesses (controls) that were admitted to The Wildlife Center of Virginia, Virginia, USA during 2003. Twenty-two bacterial isolates were identified from 17 turtles including 10 gram-negative and 12 gram-positive bacteria. Ten of 15 control animals had bacterial growth, resulting in identification of 13 bacteria, including six gram-negative and seven gram-positive agents. Seven of eight turtles with aural abscesses had bacterial growth, and 10 isolates were identified, including four gram-negative and six gram-positive organisms. The most frequently isolated bacteria from control animals were Micrococcus luteus (n = 3) and Pantoea agglomerans (n = 2). Morganella morganii (n = 2) was the only species isolated from the tympanic cavity of more than one turtle with aural abscesses. Staphylococcus epidermidis (n = 2) was the only species isolated from both groups. A trend toward greater bacterial growth in tympanic cavities of affected turtles compared with turtles without aural abscesses was noted. No single bacterial agent was responsible for aural abscesses in free-ranging eastern box turtles in this study, an observation consistent with the hypothesis that aerobic bacteria are not primary pathogens, but secondary opportunistic invaders of environmental origin.     

Bronchoscopic Diagnosis of Pulmonary Infections—Comparison of Protected-Specimen Brush and Cytology Brush With Lung Aspirates

In a recent study the use of a new plugged double-lumen protected-specimen brush with the flexible fiberoptic bronchoscope was advocated to isolate pathogens in lower respiratory tract infections while avoiding upper respiratory tract contamination. To compare the efficacy of this brush and a standard single-lumen cytology brush in identifying the etiologic agent in lower respiratory tract infections, we studied 18 patients with lung infections. Transthoracic lung aspiration was done in all but two patients in an attempt to identify the specific etiologic agent. In these two cases, cultures of specimens of blood or postmortem lung tissue yielded the causative organism. In 12 patients anaerobic or aerobic bacteria (or both) were identified, whereas one patient had a mixed bacterial and fungal infection. Using the cytology brush and the protected-specimen brush we identified at least one pathogen in 10 of 12 and 10 of 13 cases, whereas both brushes missed one or more causative organisms in 8 of 12 and 8 of 13 cases, respectively. Nonetiologic organisms were found in 8 of 12 cases by the cytology brush and 8 of 13 cases by the protected-specimen brush. Quantitative culture techniques improved the specificity of the brush results in infections where aerobes predominated. Our data show that bronchoscopic cultures of lower respiratory tract infections do not consistently recover the causative agent and are frequently subject to contamination by nonetiologic organisms. There was no difference between the brushes in avoiding contamination.     

An affinity technique for the isolation of Clostridium perfringens type C from man and pigs in Papua New Guinea

Necrotising enteritis caused by Clostridium perfringens type C (CwC) is an important cause of morbidity and death in highland regions of Papua New Guinea (PNG) and the organism is readily isolated from clinical cases. Although detected in fluorescent antibody stains of faecal cultures, CwC has previously only once been isolated from normal people or from pigs in PNG. The difficulty results from the greater numbers of the much more common Cl. perfringens type A (CwA) which is morphologically and culturally indistinguishable from CwC. Separation of CwC from the more numerous CwA has been achieved by utilising their antigenic dissimilarity. Silicate beads covered with specific antibody to CwC added to a mixed culture bound CwC cells while most of the unbound cells were washed away. When the beads were plated out type C organisms were recovered. In laboratory tests CwC was isolated from mixtures with CwA where the type A organisms predominated by one million to one. With this system type C organisms have been isolated from human and pig faeces from PNG.     

An affinity technique for the isolation of Clostridium perfringens type C from man and pigs in Papua New Guinea

Necrotising enteritis caused by Clostridium perfringens type C (CwC) is an important cause of morbidity and death in highland regions of Papua New Guinea (PNG) and the organism is readily isolated from clinical cases. Although detected in fluorescent antibody stains of faecal cultures, CwC has previously only once been isolated from normal people or from pigs in PNG. The difficulty results from the greater numbers of the much more common Cl perfringens type A (CwA) which is morphologically and culturally indistinguishable from CwC. Separation of CwC from the more numerous CwA has been achieved by utilising their antigenic dissimilarity. Silicate beads covered with specific antibody to CwC added to a mixed culture bound CwC cells while most of the unbound cells were washed away. When the beads were plated out type C organisms were recovered. In laboratory tests CwC was isolated from mixtures with CwA where the type A organisms predominated by one million to one. With this system type C organisms have been isolated from human and pig faeces from PNG.     

Etiological structure and resistance to antibacterial drugs of causative agents of cross infection in Donetsk

Tests for hemocultures were performed in 51 patients with clinical diagnoses of sepsis treated in a reanimation unit. Microbial cultures were isolated from 30 patients (58.9 per cent). Staphylococci in pure cultures and associations were the causative agents of sepsis in 26 patients (86.4 per cent). The cultures of E. coli, Y. enterocolitica and Streptococcus faecalis were isolated from 2, 1 and 1 patients, respectively. Pus specimens from 111 patients with postinjection suppuration were tested and staphylococci in pure cultures and associations were detected in 90 patients (81.8 per cent). The cultures of P. vulgaris, Streptococcus pyogenes, E. coli, Str. faecalis, Enterobacter spp. and Pseudomonas aeruginosa were isolated from 10, 5, 3, 1, 1 and 1 patients, respectively. The results showed that Staphylococci played the leading role in development of the hospital infections. Treatment of such patients should be performed with an account of antibioticograms since many strains are resistant to various antibiotics.     

医院血培养的病原菌分布及耐药性分析

目的 了解我院2006年至2008年血培养中病原菌的阳性率、分布及其对药物的敏感情况,为临床治疗菌血症提供用药依据.方法 采用自动血培养仪对血培养瓶进行连续培养监测,全自动微生物分析系统对血标本中分离的病原菌进行鉴定和药物敏感试验.结果 1002份血培养标本分离出病原菌103株,阳性率10.3%,其中革兰阴性菌58株,占56.3%;革兰阳性菌32株,占31.9%;真菌10株,占9.7%.革兰阴性菌中,大肠埃希菌、肺炎克雷伯菌对氨苄西林的耐药率最高,分别为92.7%和92.3%.革兰阳性菌中,金黄色葡萄球菌、凝固酶阴性葡萄球菌对青霉素耐药率达100%,肠球菌对常用抗生素呈高度耐药,未发现葡萄球菌对万古霉素耐药,但有9.1%的肠球菌对万古霉素呈中介.结论 目前我院血培养分离的病原菌分布较广,大肠埃希菌和葡萄球菌是菌血症和(或)败血症的主要病原菌;药敏结果提示检出菌耐药性严重且广谱耐药,及时准确的血培养结果能为临床合理选择抗菌药物提供重要依据.     

The role of encapsulated anaerobic bacteria in synergistic infections

Abstract: The effect of encapsulation on the virulence, survival, and protection of anaerobic bacteria from phagocytosis is reviewed. Support for the importance of encapsulated Gram-negative anaerobic rods ( Bacteroides sp., Prevotella sp. and Porphyromonas sp.), anaerobic and facultative Gram-positive cocci (AFGPC) was provided by their higher recovery rate in oropharyngeal infections, abscesses and blood, compared to their number in the normal flora. The pathogenicity of Bacteroides, Fusobacterium, Clostridium , and AFGPC was studied by inoculating them into mice and observing their ability to induce subcutaneous abscesses. Encapsulated Bacteroides, Fusobacteria , and AFGPC generally induced abscesses, whereas non-encapsulated organisms did not. However, many of the strains that had only a minimal number of encapsulated organisms (< 1%) survived in the abscesses, and they became heavily encapsulated when inoculated with other viable or non-viable encapsulated bacteria. Thereafter, these strains were able to induce abscesses when injected alone. Encapsulated Gram-negative anaerobic rods and AFGPC-induced bacteraemia and translocation, and increased the mortality of the infected animals more often than did the non-encapsulated form of the same strains. As determined by using selective antimicrobial therapy and quantitative cultures of abscesses induced in mice, possession of a capsule generally made Gram-negative anaerobic rods more important than their aerobic counterparts. Synergistic potentials were seen between encapsulated Gram-negative anaerobic rods and all tested aerobic bacteria and most AFGPC, and also between most AFGPC and Pseudomonas aeruginosa or Staphylococcus aureus . These studies demonstrated the importance of encapsulated anaerobes in mixed infections.     

Salicylates and reversible hearing loss

Skin and soft tissue infections were studied in 21 seriously ill narcotic addicts who had been admitted to hospital. Subcutaneous abscesses were present in 14 patients; cellulitis was noted in 3, pyomyositis in 2 and necrotizing fasciitis in 2. In four patients there was septicemia. Infections in 14 patients (66.6 percent) were associated with anaerobic bacteria, which were the exclusive isolates in 6 patients. In seven patients (33.3 percent) isolates were exclusively aerobic bacteria and in eight both aerobes and anaerobes were present. The anaerobic isolates were clostridia (six), peptostreptococci (five), bacteroides (five), peptococci (three), and one of each of Veillonella, Propionibacterium, Eubacterium, Fusobacterium and Actinomyces. Staphylococcus aureus, generally thought to be the most common cause of subcutaneous infections in addicts, was found only in four (19 percent) patients. The other aerobic isolates were Klebsiella (five) and Enterobacter (four) species. When clinical features or the Gram stain of pus suggest that anaerobic bacteria may be present, antibiotic therapy should be directed against both aerobic and anaerobic bacteria until culture results are available.     

Biofilter performance and characterization of a biocatalyst degrading alkylbenzene gases

A biofilter treating alkylbenzene vapors was characterized for its optimal running conditions and kinetic parame-ters. Kinetics of the continuous biofilter were compared to batch kinetic data obtained with biofilm samples as well as with defined microbial consortia and with pure culture isolates from the biofilter. Both bacteria and fungi were present in the bioreactor. Five strains were isolated. Two bacteria, Bacillus and Pseudomonas, were shown to be dominant, as well as a Trichosporon strain which could, however, hardly grow on alkylbenzenes in pure culture. The remaining two strains were most often overgrown by the other three organisms in liquid phase batch cultures μ _max, K_S, K_I values and biodegradation rates were calculated and compared for the difterent mixed and pure cultures. Since filter bed acidification was observed during biofiltration studies reaching a pH of about 4, experiments were also undertaken to study the influence of pH on performance of the different cultures. Biodegradation and growth were possible in all cases, over the pH range 3.5–7.0 at appreciable rates, both with mixed cultures and with pure bacterial cultures. Under certain conditions, microbial activity was even observed in the presence of alkylbenzenes down to pH 2.5 with mixed cultures, which is quite unusual and explains the ability of the present biocatalyst to remove alkylbenzenes with high efficiency in biofilters under acidic conditions.