New method for the serological grouping of Streptococci with specific antibodies adsorbed to protein A-containing staphylococci

Susceptibility of group B streptococci to 16 beta-lactam antibiotics, including new penicillin and cephalosporin derivatives

The susceptibility of 100 group B streptococci to 16 beta-lactam antibiotics was tested by agar dilution. Penicillin G and N-formimidoyl thienamycin were the most active agents tested, both having a 90% minimal inhibitory concentration (MIC90) of 0.06 microgram/ml. Ceftriaxone, cefotaxime, cefamandole, and SCH 29482 were almost as active, all having an MIC90 of 0.12 microgram/ml, and ampicillin, cephalothin, and mezlocillin all had an MIC90 of 0.25 microgram/ml. The MIC90 for piperacillin, cefoperazone, and ceftazidime was 0.5 microgram/ml. Least active were carbenicillin, ticarcillin, cefoxitin, and moxalactam, with MIC90s of 1, 2, 4, and 8 micrograms/ml, respectively. No penicillin-tolerant strains were detected.

The antistreptococcal immune responses in children with acute rheumatic fever in Kuwait

The antistreptococcal immune responses in 130 children with Acute Rheumatic Fever (ARF), seen in Kuwait, over a period of three years, are presented. The ages of children ranged between three to 13 years. One hundred and three presented in initial attacks while 27 presented in recurrences. The geometric mean of antistreptolysin 'O' (ASO) and antihyalurodinase (AH) titres for all patients were 488 Todd Units and 595 units, respectively. In children under the age of eight years, but not above this age, the geometric mean of ASO titres was significantly higher in children with carditis than in those without carditis (P less than 0.01); there was no significant difference in AH titres between the two groups. Analysis of the Geometric Mean Titres (GMT) of both antibodies in relation to other variables is also presented.

Bacterial colonization of newborn infants in a neonatal intensive care unit

The bacterial colonization of the nose, umbilicus, perineum and faeces in 85 newborns was studied during one period of high and one of low occupancy in a neonatal intensive care unit. Cultures were taken on admission, at three days, at one week of age, and then weekly during the stay in the unit. Colonization took place early and potential pathogens were responsible for a significant part of the spectrum. At one week of age, more than 50% of the infants had Staphylococcus aureus in the nose and umbilicus, 25% had E. coli and/or Klebsiella enterobacter in the umbilicus, and 60% had Klebsiella enterobacter in the perineum. Neither the occupancy rate in the unit nor the clinical state of the infant seemed to influence the colonization pattern significantly. Changes in flora were frequent in the individual infant. However, the bacterial spectrum remained essentially the same with increasing age during the stay in the unit and during the two periods. Only on two occasions was the same phage type of Staphylococcus aureus found in two infants at the same time. Two cases of septicemia occurred in the 85 infants during the three months of the study. Both infants were colonized beforehand with the causative organism. The results may indicate that the clinical state of the infant is of greater importance for risk of septicemia than the pattern of the bacterial colonization.

Direct testing of blood cultures for detection of streptococcal antigens

A direct, rapid, and simple method for the detection of streptococcal antigens of Lancefield groups A, B, C, D, and G from blood cultures was developed by using a coagglutination test. Fifty-five clinical specimens and 117 simulated blood cultures containing gram-positive cocci were tested. Out of 6,261 clinical blood cultures screened, 55 cultures from 53 patients were positive, with organisms resembling streptococci, by Gram stain. Of these cultures, 78% (43 of 55) were pure cultures of streptococci, and 22% (12 of 55) were mixed with at least one other organism. Of the 43 pure cultures only, correct reactions were obtained (grouping correctly or giving no cross-reactions, or both) with 86% (37 of 43) of the isolates, 12% (5 of 43) exhibited cross-reactions, and 2% (1 of 43) gave false-negative reactions. All of the cross-reacting isolates were Streptococcus pneumoniae, which reacted with the group C reagent, and the false-negative reaction occurred with a Streptococcus bovis isolate. However, by using a direct modified bile solubility test, the correct identification of the S. pneumoniae isolates was obtained. Therefore, by using the modified bile solubility test in conjunction with the direct grouping method, 98% (42 of 43) of the isolates in pure culture could be identified accurately and rapidly after the detection of a positive Gram stain. Correct grouping reactions were obtained with 83% (10 of 12) of the mixed blood cultures, and false-negative results occurred with 17% (2 of 12) of them. Both cultures contained an enterococcus and a gram-negative rod. Of the 117 simulated blood cultures, there was only one incorrect grouping reaction; this occurred with an S. bovis isolate that cross-reacted with the group C reagent. The direct grouping reaction was positive when blood cultures contained a minimum of 1 x 10(8) to 8 x 10(8) colony-forming units per ml. In general, this procedure provided information on the identification of the organism 24 h earlier than by conventional identification methods.

Serological grouping of streptococci: a collective evaluation in six laboratories of three rapid methods

Three serological methods for streptococci grouping: latex agglutination after pronase extraction (LAP), latex agglutination after nitrous acid extraction (LAN) and counterimmunoelectrophoresis after nitrous acid extraction (CIEN) were evaluated in six laboratories with 310 strains of streptococci. To reduce the possible influence of a particular laboratory, each serological procedure was performed in two different laboratories with identical protocols and strains. Between the three procedures, a total agreement of 81.3% with six identical results was obtained. Since only one discordant result was obtained in 12.2% (CIEN 4.8%-LAN 5.8%-LAP 1.6%) and two discordant results with two different serological methods in 2.6%, it could be concluded that agreement between the three procedures was 96%. For B (99 strains tested) and D(100 strains tested) groups, total agreements of respectively 95% and 92% were achieved. In conclusion, LAP, LAN, and CIEN gave equivalent results for streptococci grouping, but LAN was the most simple needing no heating, centrifugation, or electrophoresis equipment and lacking cross-reactivity of group C antibody.

Evaluation of an improved Streptex kit for the grouping of beta-haemolytic streptococci by agglutination

A modified Streptex kit in which the extraction procedure had been simplified was used to group 200 streptococcal strains. Positive reactions could be obtained with live colonies and over 90% of isolates were correctly grouped from primary isolation plates. Some minor cross-reactions were seen with Streptex, but these were not strong enough to cause any confusion and no isolates were incorrectly grouped. The extraction enzyme in the Streptex kit was relatively poor at extracting the group-specific teichoic acid of group D strains but worked well with groups A, B, C, F and G.

Comparison of the API 20S Streptococcus identification system with an immunorheophoresis procedure and two commercial latex agglutination tests for identifying beta-hemolytic streptococci

The API 20S Streptococcus identification system and a new immunorheophoresis procedure were evaluated as means for determining the Lancefield serogroup of beta-hemolytic streptococci recovered from human clinical specimens. The serogroup of 96 strains was determined by these methods and by two commercially available latex agglutination tests. Streptex and SeroSTAT. The results of all four procedures were compared with the results of a classical precipitin test. The API 20S system correctly categorized 92.7% of the isolates; 94.8% were correctly identified by the immunorheophoresis procedure. The latex agglutination procedures were of comparable accuracy, yielding correct identifications with approximately 92% of the strains tested.

Preliminary identification of beta-hemolytic streptococci in throat swab cultures with a commercial blood agar slide (streptocult)

A commercial blood agar slide (Streptocult, Orion Diagnostica) was used for preliminary identification of beta-hemolytic streptococci of groups A, C, and G in throat swab specimens. The sensitivity of the test was 93.6% and the specificity was 94.7%, as judged from 580 specimens. A model is suggested for routine processing of throat swab specimens, involving inoculation and reading of the slide in general practice and transport of positive or inconclusive slides to a bacteriology laboratory for isolation and serological grouping of beta-hemolytic streptococci. The model combines preliminary detection of beta-hemolytic streptococci within 24 h with the reliability of serological groupings, and should reduce the volume of specimens sent to the laboratory considerably.

Receptor in group C and G streptococci detects albumin structures present in mammalian species

The presence of albumin structures with the capacity to bind to a surface receptor in group C and G streptococci was studied in serum samples from 45 mammalian species representing 15 different orders, using an inhibition assay. The ability of animal sera to inhibit the uptake of radiolabeled human serum albumin by the streptococci indicated the presence of such albumin structures. Positive reactions were found in species of most orders tested, with Marsupialia as a notable exception. All Carnivora sera tested were strongly positive. In some orders such as Artiodactyla both positive and negative species were identified. Serum samples from 62 bird species representing 15 orders and from 5 fish species were also tested in the inhibition assay. None of these serum samples was capable of inhibiting the uptake of human serum albumin by streptococci. Some differences were also noted in the results obtained with group C and G streptococci from human and bovine sources, respectively, indicating the presence of two types of receptors. The present studies suggest a phylogenetic origin of albumin structures with affinity for the streptococcal receptor to a period after the divergence of Marsupialia from the other mammalian orders.

Haemophilus influenzae, Pneumococci, group A streptococci and Staphylococcus aureus: sensitivity of outpatient strains to commonly prescribed antibiotics

The degree of resistance of Haemophilus influenzae, pneumococci, group A streptococci and Staphylococcus aureus to phenoxymethylpenicillin, ampicillin, doxycycline, erythromycin and chloramphenicol was investigated with the MIC-method (plate-dilution technique). Each bacterial group consisted of 100 outpatient strains. Seven strains of H. influenzae were beta-lactamase-producing. Of the 100 haemophilus strains, 58% were sensitive and the rest intermediate sensitive to erythromycin. 99% were sensitive to doxycycline and all strains were sensitive to chloramphenicol. Essentially all pneumococcal strains were sensitive to the antibiotics tested. However, a few strains demonstrated diminished sensitivity to penicillins. All group A streptococci were sensitive to ampicillin, penicillin and chloramphenicol, and 98% were sensitive to erythromycin. Approximately 1 strain out of 5 was resistant to doxycycline. 75% of S. aureus were beta-lactamase producers. Four of the S., aureus strains were resistant to erythromycin and 8 to doxycycline. The results presented indicate a better antibiotic situation than in some other countries, but suggest the need for a more extensive antibiotic sensitivity examination of isolated bacteria.

Evaluation of Phadebact and Streptex Kits for rapid grouping of streptococci directly from blood cultures

The Phadebact Streptococcus Test and the Streptex Test kits were evaluated for grouping streptococci directly from blood cultures. Pellets of bacteria obtained from centrifuged samples of positive blood cultures were inoculated into Todd-Hewitt broth for 2- and 4-h Phadebact tests and into pronase for Streptex tests. Hemolysis was determined after pipetting a portion of each pellet into cuts made in blood agar plates incubated anaerobically for 2 to 6 h. Serological groups were also determined from colonies of the 137 strains of streptococci used in the study by the Lancefield precipitin method. Of the 126 strains tested by the 4-h Phadebact method, 120 (95.2%) agreed with Lancefield groupings, and 133 (97.1%) of the 137 strains tested by Streptex were in agreement. In contrast, only 31 of 55 strains (56.4%) were correctly identified by the 2-h Phadebact method. Misidentifications were related to multiple agglutinations and weak agglutinations in homologous antisera. Group A isolates were most frequently misidentified by all of the test methods. Hemolysis was determined within 4 h for 92.7% of the isolates and within 6 h for the remaining strains. Although the 4-h Phadebact procedure and the Streptex procedure were comparable in overall accuracy, cost, and technologist time, Streptex was the method of choice for direct groups. Results were available within 75 min for the Streptex procedure compared with 4 h for the Phadebact method. Because few cross-reactions occurred, agglutination responses were clearer and easier to interpret. Results from 2-h Phadebact tests were not satisfactory, and this method is not recommended.

An indirect immunofluorescence staining procedure for detection of human Fc gamma receptors on streptococci

Fc gamma receptors on streptococci are usually revealed by hemagglutinating techniques (IgG coated red blood cells) or uptake of radiolabeled IgG. The results obtained with these methods are not always satisfactory. For this reason, we developed a technique involving indirect immunofluorescence staining. Bacterial smears were treated with human Fc gamma fragment and their binding to streptococcal Fc gamma receptors was revealed by a fluorescent F(ab')2 fragment of anti-human Fc gamma sheep antibodies purified on an IgG immunosorbent. These purified sheep F(ab')2 fragments did not contain any IgG nor Fc gamma as shown by SDS polyacrylamide gel electrophoresis. Under these conditions indirect immunofluorescence staining was a highly specific and sensitive method of detecting Fc gamma receptors on streptococci. Distribution of Fc gamma receptors was studied in 237 streptococcal strains of human origin belonging to groups A, B, C, D and G; these receptors were also looked for in 21 strains of alpha-hemolytic streptococci which did not possess the group carbohydrate and 12 strains of pneumococci. Fc gamma receptors were found only in group A, C and G streptococci, but all strains of these groups did not possess Fc gamma receptors.

A simple and rapid test for the identification of clinical herpes simplex virus isolates

A simple procedure is described which permits the rapid identification of clinical herpes simplex virus isolates. The test utilizes Staphylococcus aureus to which anti-viral immunoglobulins had been adsorbed. Adherence of the antibody-coated bacteria to virus-infected cells is readily seen by light microscopy. Indirect immuno-fluorescence and the S aureus adherence reaction were found to be approximately of equal sensitivity for the detection of virus antigens.

Experimental necrotic dermatosis induced by group G streptococci in mice

Self healing necrotic lesions were produced on the backs of laboratory mice by injecting group G streptococci into the skin. The incidence and severity of necrotic dermatosis was dose related. When 1 x 10(1) colony forming units (cfu) were injected subcutaneously, lesions developed on three of 16 mice 4 days post inoculation. Injection of 1 x 10(3) cfu produced lesions on five of 16 mice and 1 x 10(5) cfu produced lesions on seven of 15 mice 3 days post inoculation. An inoculation of 1 x 10(7) cfu produced lesions on all of 16 mice 2 days post inoculation. Lesions produced by the 1 x 10(1) inoculum were smaller and had healed by the 15th day post inoculation, whereas lesions produced by the 1 x 10(7) inoculum persisted until the 24th day post inoculation. No mortality could be attributed to experimental design and all lesions healed without the use of medication or antibiotics.

Simplified coagglutination test for serological grouping of beta-hemolytic streptococci

A new coagglutination kit consisting of a plastic slide with dried antibody-coated staphylococci was evaluated for the grouping of beta-hemolytic streptococci of groups A, B, C, and G. The test was compared with the classical precipitation test, using hot formamide antigen extracts with 224 strains of groups A, B, C, and G streptococci. An agreement of 100% was found between the new coagglutination and the classical precipitation procedures. No false-positive results were obtained with group F and D streptococci; however, group L streptococci reacted with the group A reagent. The test procedure could be shortened by using suspensions of colonies from overnight cultures on blood agar plates in small volumes of Todd-Hewitt broth without further incubation. All 74 strains of groups A, B, C, and G were correctly identified from suspensions in Todd-Hewitt broth; however, suspending the colonies in 0.9% saline or phosphate-buffered saline resulted in lower sensitivities.

Staphylococcal protein-A agglutination assay for avian viruses

Protein-A rich staphylococci were used to develop an agglutination assay for the detection and quantitation of avian reticuloendotheliosis virus (REV) and Herpes virus of turkeys (HVT). Rabbit anti-REV or anti-HVT were used to coat the staphylococci and these reagents were mixed with REV or various other viral antigen preparations. An agglutination titer was determined for antigen preparations of varying purity and the results indicated that in addition to being rapid, this assay allows the detection of as little as 0.3 to 0.5 microgram of partially purified viral antigens. No crossreactivity was observed with the two antisera and the various antigen preparations. This study also confirmed the reports in the literature that chicken immunoglobulins do not bind to protein-A of the Cowan I strain of Staph. aureus.

Rapid presumptive identification of Cryptococcus neoformans by staphylococcal coagglutination

A coagglutination reagent was prepared by sensitizing the Cowan I strain of Staphylococcus aureus with rabbit immune globulin directed against Cryptococcus neofromans A15 and absorbed with C. laurentii. This reagent was evaluated for its usefulness in differentiating C. neoformans from other yeast colonies rapidly. Antigen-containing extracts were prepared form Sabouraud dextrose agar cultures of 48 C. neoformans, 33 other Cryptococcus species, 21 Candida, 4 Torulopsis, 3 Saccharomyces, and 2 Rhodotorula strains. This was done by suspending a 0.001-ml loopful of colony growth in 0.5 ml of phenolized saline, mixing for 30 s, and then centrifuging. Equal volumes (50 microliters) of coagglutination reagent and yeast extract were mixed within marked circles on a glass slide and then mechanically rotated at 180 rpm for 8 min. Forty-five of the 48 strains of C. neoformans produced strong (3+ to 4+) agglutination, and 3 strains of serotype C produced weak (1+ to 2+) agglutination with the reagent. Other Cryptococcus species which reacted positively were 4 C. albidus subsp. diffluens, 7 C. albidus subsp. albidus, and 2 C. terreus strains; however, false-positive errors in identification were circumvented by performing a supplemental rapid test for nitrate utilization which differentiated these yeasts from C. neoformans. None of the other yeasts tested (including 14 C. laurentii, 2 C. luteolus, and 2 C. uniguttulatus strains) produced any degree of agglutination with the reagent. A commercial cryptococcal latex agglutination reagent (Crypto-Test, Microbiological Associates, Walkersville, Md.) proved less reliable for identifying C. neoformans yeast colonies because of cross-reactions which occurred with all other species of Cryptococcus tested.

A rapid slid coagglutination test-an alternative to the fluorescent antibody test for the identification of Neisseria gonorrhoeae

The Phadebact(R) Gonococcus Test, a slide coagglutination test, was compared with the Difco fluorescent antibody test for the identification of Neisseria gonorrhoeae isolated from 18- to 24-hour primary plates. A total of 316 morphologically characteristic, oxidase-positive, Gram-negative diplococci were tested. Altogether 298 isolates were identified definitively as N. gonorrhoeae by a rapid carbohydrate utilisation test; 287 of the 298 isolates of N. gonorrhoeae were identified by the coagglutination test, a sensitivity of 96%. The sensitivity of the fluorescent antibody test was 85% (254 of 298 isolates). False-positive results due to cross-reactions with non-gonococcal Neisseria were uncommon (1 of 18 non-gonococcal isolates in the coagglutination test, a specificity of 94%; 2 of 18 in the fluorescent antibody test, a specificity of 88%). None of the 14 other contaminant organisms seen frequently on primary isolation media gave positive reactions. Interpretation of the coagglutination test proved to be difficult initially. Thirty-two (10%) coagglutination tests had to be repeated; 3 of the 32 (1% of the total isolates tested) remained uninterpretable.

Receptors for fibrinogen and aggregated beta 2-microglobulin detected in strains of group B streptococci

Binding of radiolabeled human fibrinogen and aggregated beta-microglobulin was measured in 60 strains of beta-hemolytic group B streptococci. Positive fibrinogen binding was detected in seven of the strains. Six of the group B strains showed an uptake of aggregated beta 2-microglobulin. Four individual strains carried both receptors, indicating a positive correlation between their occurrence. Inhibition studies showed that fibrinogen competed sterically with beta 2-microglobulin binding. Receptors for both proteins were trypsin sensitive. The presence of receptors did not correlate with the serological type of the 49 group B strains tested. However, all seven type II strains were negative. No uptake of fibrinogen was noted in any of 40 group D strains tested. Binding structures for fibrinogen and aggregated beta 2-microglobulin detected in group B streptococci were similar to receptors for the same proteins in group A, C, and G streptococci in terms of mutual correlation and steric interference of binding. The occasional occurrence of these receptors also in group B strains might reflect a common origin of some types of surface proteins in gram-positive cocci.

Analysis of bacterial cell wall proteins and human serum proteins bound to bacterial cell surfaces

A method was developed for the characterization of proteins non-covalently bound to the cell wall of Gram-positive cocci. The method employs radioactive labelling of cell wall proteins followed by solubilisation and analysis on polyacrylamide gel electrophoresis in sodium dodecyl sulphate. Using this experimental procedure, protein patterns obtained from group A, C and G streptococcal strains showed marked similarities within each group. Protein peaks were also found to be shared between group C and G strains. Two major peaks with molecular weights of about 30 000 and 70 000 characterized group A strains, whereas group C and G strains showed one consistent peak of about 45 000, thus reflecting the closer relationship between these two groups as compared to group A streptococci. By incubating bacteria with human serum proteins before labelling, solubilisation and electrophoretic analysis, it was also possible to study external proteins specifically bound to the bacterial surface. A group G streptococcus, strain G 148, showed protein peaks corresponding to its known specific binding of human albumin and immunoglobulin G, but also additional protein peaks. When Staphylococcus aureus, strain Cowan I, was pre-incubated with human serum in excess, protein peaks corresponding to heavy and light chains of immunoglobulins were seen. Three more protein peaks of serum origin were also detected, indicating binding of proteins other than Ig to S. aureus. Experiments with protein A-coated Sepharose beads resulted in the same protein pattern, suggesting that binding of these different polypeptides is indeed mediated by protein A.

A rapid quantitative staphylococcal co-agglutination assay. Utilization for the assay of bovine factor VIII-related antigen

A simple and rapid technique to measure bovine factor VIII-related antigen has been developed which utilizes protein A-bearing staphylococci and monospecific rabbit antiserum to bovine factor VIII. Staphylococci coated with a specific antibody agglutinate when they are mixed with the specific antigen. We have used an aggregometer to detect an quantitate the agglutination of the antibody-coated staphylococci. The assay has been optimized with respect to amount of antiserum needed for coating staphylococci, concentration of antibody-coated staphylococci, pH and ionic strength of the assay system, and stirring speed of the aggregometer. The staphylococcal co-agglutination assay as monitored by an aggregometer is at least 10 times more sensitive than the conventional slide agglutination method, and can detect as little as 0.1 microgram/ml of factor VIII antigen. It however, cannot be used to quantitate factor VIII-related antigen in plasma, since plasma contains some components which can non-specifically agglutinate staphylococci.

High isolation rate of Branhamella catarrhalis from the nasopharynx in adults with acute laryngitis

Branhamella catarrhalis was isolated from the nasopharynx in 55% of 40 noncompromised adult patients suffering from acute laryngitis. Diplococcus pneumoniae and haemophilus influenzae were found in another 5 and 8%, respectively; one patient had group A streptococci in the throat specimen. In 90% of the patients the laryngitis complaints were preceded by symptoms of an acute respiratory tract infection. Two of the patients with B. catarrhalis showed a significant titre conversion against influenza B and parainfluenza type e virus, respectively. Attempts to isolate virus failed in all cases. The results indicate that B. catarrhalis, known to cause acute otitis media in small children and respiratory tract infections in adult compromised hosts, may be involved in the etiology of acute laryngitis in otherwise healthy adults.

Microbiological findings in pregnant women with premature rupture of the membranes

From 30 consecutive cases of premature rupture of the membranes (PROM) and matched controls, specimens from urine, cervix, amniotic fluid, and placenta as well as neonatal nose and throat swabs were investigated bacteriologically and virologically. In addition virus serological investigation was done. Among the PROM cases the anaerobic cervical isolates outnumbered the aerobic ones, and the total number of aerobic as well as anaerobic isolates was less in the control group. The anaerobes B. fragilis and Strept. intermedius were isolated from the cervix, amniotic fluid, or placenta in 23% and 30% of the PROM patients, respectively. None of the controls harboured B. fragilis, while Strept. intermedius was isolated from 6.7% of the controls. Group B streptococci were recovered from the mother's cervix in 20% of the PROM patients and in 6.7% among the controls. Four cases of neonatal septicaemia were encountered, and another two cases were clinically suspected, but not microbiologically verified, contributing to a high perinatal mortality rate (17,6%). Of the PROM patients, 27% developed puerperal infection, while none of the control mothers had such complications. The significance of the anaerobic bacteria as well as group B streptococci for the maternal and neonatal outcome in cases of PROM is discussed, and a possible aetiological role of ascending infection in this complication of pregnancy is postulated.

Immune complexes and complement in serous and mucoid otitis media

The occurrence and quantity of immune complexes in middle ear effusion (MEE) and serum, as well as serum levels of complement (C) factors were investigated in patients with chronic otitis media. Immune complexes were demonstrated in 85% of the serous MEE and in 28% of the sera. Depressed Clq values and presence of abnormal complexes, composed of subcomponents of the first C factor, indicated a disturbed function of the C system. Activation of C by the classical pathway was demonstrated in 23% of the patients. Decreased levels of properdin were also noted. The disorders within the C system tended to normalize as the otitis subsided.

Bacteria associated with acute otitis media have high Clq binding capacity

A simple, rapid and sensitive radioimmunologic method for demonstrating Clq binding to bacteria is described. Various bacteria were shown to bind Clq without the participation of antibodies. Great differences in Clq binding levels between different types and strains of S. pneumoniae were found. A high uptake of Clq was observed for many pneumococcal strains of type VI, XIX and XXIII and also for non-typable strains of H. influenzae and B. catarrhalis. Other bacteria tested, including H. influenzae types a-f, demonstrated less capacity to bind Clq.

Use of the Streptosec test for grouping beta-haemolytic streptococci

The Streptosec test, which embodies the coagglutination principle for grouping beta-haemolytic streptococci, was used against 72 streptococci previously grouped by precipitin methods. Only two of the 72 strains failed to react. The test is easy to manipulate, represents a considerable saving in time and effort, and produces results with an acceptable degree of accuracy.

Grouping of beta-haemolytic streptococci by agglutination

Streptococcal grouping sera, diluted and absorbed to remove cross-reactions, were bound to staphylococci and used to group trypsinised beta-haemolytic streptococci by coagglutination. The results compared well with those obtained using the Phadebact streptococcal grouping kit. The same sera bound to staphylococci without prior dilution and absorption could be used to group enzyme extracts of haemolytic streptococci by slide agglutination, the results again comparing favourably with those of the Phadebact kit.

Comparison of slide coagglutination test and countercurrent immunoelectrophoresis for detection of group B streptococcal antigen in cerebrospinal fluid from infants with meningitis

The usefulness of Phadebact streptococcus reagents for the detection of group B streptococcal antigen in cerebrospinal fluid was evaluated in 54 infants with meningitis and in 22 normal infants. Antigens was detected by slide coagglutination in 19 (82.6%) and by countercurrent immunoelectrophoresis in 20 (87.0%) of 23 cerebrospinal fluid specimens from infants with group B streptococcal meningitis at admission. After initiation of antimicrobial therapy, antigen could be detected in 11 of 19 (by slide coagglutination) and 7 of 18 (by countercurrent immunoelectrophoresis) cerebrospinal fluids. False-positive reactions were noted by slide coagglutination in one infant with S. bovis meningitis and one with group B streptococcal bacteremia without meningitis; none occurred with countercurrent immunoelectrophoresis. The commercial availiability, simplicity, sensitivity (82.6%), and specificity (96.4%) of the Phadebact slide coaggluatination test for detecting group B streptococcal antigen in cerebrospinal fluid suggest that it may be useful for the early and rapid diagnosis of group B streptococcal meningitis.

Evaluation of three commercially available test products for serogrouping beta-hemolytic streptococci

Three beta-streptococci serogrouping kits, Phadebact, SeroSTAT, and Streptex, were evaluated as to their sensitivity, accuracy, and suitability as methods for serogrouping streptococci in a clinical microbiology laboratory. The majority of the primary isolates examined by the various methods associated with each of the three kits were correctly identified. The Streptex direct mixed-culture procedure was more often associated with the observation of cross-reactivity than with the direct procedures of the other two kits which did not employ mixed growth cultures. Furthermore, the Streptex kit was associated with more false-negative responses than those determined by the other two kits under evaluation. These results appeared to be due to the relatively poor sensitivity of the Streptex grouping reagents. The Streptex test procedures required more labor than the other kit procedures, requiring a 1-h enzymatic extraction step for the release of the group antigens. The SeroSTAT kit provided only a direct procedure and, thus, is limited in its application. The Phadebact procedures were the most versatile by providing not only a direct and a 24-h grouping procedure, but also by including a 4-h method that may be employed as required by the clinical microbiologist.

Demonstration of a new type of immunoglobulin G receptor in Streptococcus zooepidemicus strains

Forty-seven bacterial strains representing four different group C streptococcal species were tested for binding of human and bovine immunoglobulin G (IgG) subclasses. Specific binding sites for IgG were found in all bacterial species studied. The four species included differed, however, in their capacities to interact with various IgG subclasses, indicating the existence of different types of IgG receptors. Streptococcus equisimilis and Streptococcus dysgalactiae were found to carry the same type of IgG receptor, one that is identical to the previously described Fc-binding structure type III. A new type of bacterial IgG receptor was detected in Streptococcus zooepidemicus strains. This receptor exhibits a protein A-like subclass specificity, with binding of human IgG1, IgG2, and IgG4 and of bovine IgG2. However, differences in their capacities to interact with other non-human immunoglobulins indicated that these two immunoglobulin-reactive structures were different. All types of IgG receptors in group C streptococci were found to be heat stable but susceptible to proteolytic enzymes. The inability of human serum albumin or fibrinogen to inhibit the uptake of radiolabeled IgG shows that the IgG receptor is separate from binding sites for these two other proteins on the bacterial cell surface. The existence of similar IgG receptors in closely related streptococcal species suggests that these structures have a common origin.

Evaluation of the phadebact gonococcus test, a coagglutination procedure for confirmation of Neisseria gonorrhoeae

Rapid and accurate immunological confirmation of presumptively positive gonococci could be facilitated with the Phadebact Gonococcus Test, a slide coagglutination procedure. The test was compared with carbohydrate utilization and fluorescent-antibody tests on 235 clinical isolates. With the coagglutination procedure, 97.1% of the isolates were identified as compared with 93.1% by carbohydrate utilization and 98.7% by fluorescent antibody. The Phadebact test was highly specific, showing no cross-reactions with 55 other Neisseria species or with 50 miscellaneous organisms occasionally found growing on selective culture media. Because of its high sensitivity and specificity, ease of performance, and ability to provide results in 2 to 3 min, this procedure provides a suitable alternative to the carbohydrate utilization and fluorescent-antibody tests for confirmation of N. gonorrhoeae.

Coagglutination as an expedient for grouping Escherichia coli associated with urinary tract infections

Thirteen serogroups of Escherichia coli most frequently are responsible for urinary tract infections in humans. Knowledge of serogroup is required for epidemiological reasons and to help differentiate between new and reemergent strains in infected patients. Coagglutination and bacterial agglutination were compared as serodiagnostic tools for identifying groups of E. coli associated with these infections. In contradistinction to bacterial agglutination, coagglutination showed no cross-reactions for 12 of the 13 known strains obtained from the Center for Disease Control. A single antiserum, E. coli O4, caused bacterial agglutination and not coagglutination. In addition, staphylococcal cells that were coated with antiserum reacted with sheep erythrocytes that had been treated with soluble extract of E. coli. The latter reaction, cohemagglutination, was as specific and rapid as coagglutination; easily visible patterns of clumping developed within 1 min after sensitized staphylococci and E. coli reagent were mixed. These results revealed a method that is sensitive and reproducible for identifying serogroups of E. coli responsible for urinary tract infections.

Demonstration of specific binding sites for human serum albumin in group C and G streptococci

A total of 297 bacterial strains belonging to 27 species was tested for quantitative uptake of radiolabeled human serum albumin. Specific binding sites with high affinity for human serum albumin were found exclusively in group C and G streptococci. The albumin binding was found to be a time-dependent, saturable, and displaceable process which obeyed simple kinetic equations. Scatchard analysis revealed that human serum albumin bound to a homogeneous population of receptors with an affinity in the order ot 10(7) liters/mol and that the average bacterial cell carried more than 80,000 binding sites. The albumin receptor is a heat-stable component susceptible to proteolytic digestion. It has a surface localization separate from the receptors for immunolgobulin G, fibrinogen, aggregated beta 2-microglobulin, and haptoglobin. In individual strains, albumin reactivity was also detected independently of these other types of interactions with human proteins.

Coagglutination as a test for Neisseria gonorrhoeae

After growth on Thayer-Martin medium, 196 strains of freshly isolated Neisseria gonorrhoeae were subjected to a coagglutination reaction. The sensitivity of the test was 94% and did not vary much in the hands of four consecutive technicians. In a group of 99 strains tested by one of the technicians non-interpretable results were obtained with 17% of the strains when the test was performed with cells taken from the first or primary plate, against 9% when cells from the secondary (subcultured) plate were used. The lowest number of non-interpretable results was found with a modified Thayer-Martin medium, which also showed the lowest number of false negatives (2%). No non-interpretable results were obtained when the bacterial suspension was first heated to 100 degrees C for 3 min. In a group of 14 recently isolated strains of non-gonococcal species there was only one, preventable, false-positive strain and there were none in a group of 12 meningococci (all of them laboratory strains). In comparison with the fermentation test with Lingelsheim's sugars, the coagglutination test with cells taken from the primary plate with Thayer-Martin medium yielded a conclusive result more often. The test is simple and rapid and does not require special technical equipment. It seems to deserve a place as a confirmative test in the search for gonococci in samples from the urogenital-anal area.

Prevalence of nine different micro-organisms in the female genital tract. A comparison between women from a venereal disease clinic and from a health control department

In a study of the prevalence of nine different micro-organisms in the female genital tract in a Swedish population, significantly higher isolation rates occurred among women attending a venereal disease clinic than among those attending a gynaecological health control department. The prevalence of Candida albicans, however, was similar in different groups, individual susceptibility being the most important factor. Chlamydia trachomatis, Trichomonas vaginalis, and Mycoplasma hominis occurred concomitantly with Neisseria gonorrhoeae, indicating a similar epidemiology for all these agents. Younger patients seemed to have an increased susceptibility to C. trachomatis whereas older patients had an increased susceptibility to T. vaginalis.

Serological grouping of streptococci by slide agglutination

Streptococcal grouping sera for groups A, B, C, and G prepared for conventional testing by precipitation were made specific by absorption and used to identify streptococci by slide agglutination with and without staphyloccocal coagglutination. Trypsinised suspensions of 1055 strains, identified by precipitation as belonging to group A, B, C, or G, were tested by slide agglutination. Of these, 998 were correctly identified using a streptococcal suspension and antisera alone and a further 65 were identified when a loopful of protein A-positive staphylococci was added. Suspensions of 88 strains not of groups A, B, C, or G gave no reaction in the agglutination test with or without the addition of staphylococci. Group polysaccharide extracted by conventional methods also caused agglutination of staphylococci on a slide when specific antiserum was added. Growth from primary or secondary cultures digested in streptomyces enzyme for only 15-30 minutes provided an excellent antigen for a quick and simple method of streptococcal grouping using non-sensitised staphylococcal suspension and specific antisera for coagglutination.

Grouping of streptococci by Streptex

Streptex was compared to routine laboratory identification methods available. The results from Streptex sometimes required several attempts before final identification could be achieved. In the main, group D streptococci other than Strep. faecalis failed to group with the Streptex antisera, and this method cannot therefore be used exclusively as a means of identifying this group of streptococci.

Evaluation of commercial latex agglutination reagents for grouping streptococci

A total of 155 strains of beta-hemolytic streptococci were serologically grouped by conventional techniques (Lancefield extraction and capillary precipitin testing) and by latex agglutination (LA). Agreement between conventional and LA techniques was 97% when the instructions of the manufacturer for the LA technique were followed. Agreement of 99% was obtained when modified autoclave extracts were used as antigens in the LA procedure. A total of 82 strains of non-beta-hemolytic streptococci were also tested by conventional, prescribed LA, and modified autoclave procedures. The agreement between conventional techniques and both LA procedures was 76%. However, when serological cross-reactions in the conventional grouping procedures were considered as errors, the accuracy of identification of both LA procedures was 88% among the non-beta-hemolytic strains. Of 13 strains of Streptococcus bovis, 10 did not react with the LA group D reagent but were serogroup D by conventional techniques. More S. bovis strains were grouped by the LA technique when extracts of 20 ml of broth cultures were used as antigens; however, cross-reactions were observed with non-group D strains when this technique was applied to them.

Quantitative assay of soluble beta-hemolytic streptococcal antigens via an immunochemical turbidimetric method with a spectrophotometer

Soluble, group A, B, C, and G beta-hemolytic streptococcal antigens were successfully identified in a prototype spectrophotometric system by an immunochemical turbidimetric assay. Any spectrophotometic system which can take a zero reading followed by a second reading 2 or more min later can be used for the assay. Maximum absorbance was obtained near a wavelength of 340 nm. A wide range of linearity between antigen concentration and absorbance was observed at some antibody dilutions, resulting in a simple assay which can be used to quantitate amounts of antigen in solution. Minimal cross-reactions that present no problem in interpretation was observed. Simulated emergency samples were solubilized and assayed for group A and B bacteria within 3 h of colony recognition. Reproducibility of the absorbance resulting from the antibody-antigen reaction was great, with low coefficients of variation over a period of 50 days. The simplicity of the assay solutions, requiring only antisera and a buffer, and the accessibility to high levels of quality control are among the greatest assets of the technique to clinical laboratories.

Effect of phenoxymethylpenicillin and clindamycin on the oral, throat and faecal microflora of man

Phenoxymethylpenicillin in capsules was given orally in doses of 800 mg twice daily for 7 days to 10 subjects. Saliva, throat and faecal specimens were taken up to 29 days for cultivation of aerobic and anaerobic bacteria. No changes in the normal flora in saliva, throat or faeces were noticed during the observation period. Clindamycin was given orally in doses of 150 mg 4 times daily to 10 other subjects. No changes in the aerobic oral flora were observed, while a significant decrease in the number of anaerobic bacteria occurred. In 2 volunteers, overgrowth of clindamycin-resistant clostridia were seen from days 4--16 in one and from days 2--7 in the other. The throat flora showed changes similar to the oral flora. Pronounced changes in the aerobic and anaerobic faecal bacterial flora occurred. Thus among the aerobes enterococci proliferated and among the anaerobes significant decreases in the number of cocci and gram-negative rods were noticed. In 4 subjects, clindamycin-resistant clostridia increased 4log. One of them developed diarrhoea and harboured an unidentified toxin-producing clostridial strain rather similar to Clostridium difficile.

Upper respiratory tract spread of group B streptococci type I b in a kindergarten

In a kindergarten with 42 children and 17 female staff members, an epidemic of group B streptococcal carriage in the upper respiratory tract occurred. In the middle of February 1978, 6 children and 5 adults carried type I b streptococci in the throat while only 2 of these 11 were carriers 2 weeks later. Only one other streptococcus, belonging to type II, was found in the throat specimens. Five strains other than type I b were found in the urogenital tract of the staff. Three type I b throat carriers were also urogenital carriers of this type. The spread of type I b streptococci could have resulted from co-spreading with other upper respiratory tract pathogens found, including group A streptococci of type 12. Haemophilus influenzae, Branhamella catarrhalis and pneumococci. Estimation of antibodies with radiolabelled protein A indicated an immune response to type I b, but not to types I a, II or III group B streptococci in the staff compared with healthy blood donors.

Studies of the human lymphocyte-mouse erythrocyte bond

A subpopulation of human B lymphocytes forms rosettes with mouse erythrocytes through a glycoprotein-dependent bond. Further studies of this bond show that the lymphocyte receptor is not immunoglobulin, although the binding of antisera or staphylococci to surface immunoglobulin inhibits the formation of mouse rosettes. Rosette formation could not be induced in thymocytes by enzymatic modification of the surface, or in T cells by lectin-induced transformation. The capacity to bind mouse erythrocytes was lost after incubation in a serum-free medium of lymphcytes from most patients with chronic lymphocytic leukaemia (CLL) and normal subjects. This loss could be prevented by the addition of a variety of sera and glycoprotein-containing substances to the medium, including fetuin. Conditions conductive to the subsequent restoration of rosetting capacity could not be found, indicating that the loss of this capacity was not due to the shedding of a cell-surface receptor which could be re-synthesized. It is suggested that the functional receptors in B1 lymphocytes are held in aggregates by cross-linking peripheral glycoprotein molecules; disaggregation and consequent loss of the capacity to form rosettes with mouse erythrocytes occurs during incubation in serum-free media, and during maturation of lymphocytes to the B2 stage.

Modified coagglutination procedure for the serological grouping of streptococci

Cowan I staphylococci coated with antisera to streptococcal groups A, B, C, D, F, and G were used as coagglutination reagents in a modified coagglutination procedure (MCAP). Streptococcal group antigens were extracted with a Streptomyces albus-lysozyme enzyme mixture for 30 min at 55 degrees C and centrifuged, and the supernatant was tested by slide coagglutination. Positive coagglutination reactions occurred within 30 s. The cell pellets from overnight broth cultures and colonies taken directly from sheep blood agar plates were tested and compared with the results of the Lancefield capillary precipitin method. Of the 102 strains of broth-grown cells tested, 100 were grouped by the MCAP and the Lancefield capillary precipitin method. The remaining two isolates were serologically identified only by the MCAP. Of the original 102 strains, 97 were tested by MCAP after extraction of five well-isolated colonies from a sheep blood agar plate. When this latter method was used, 95.9% of the strains were correctly identified. Nonspecific reactions were observed only while testing the MCAP with the direct plate assay. These cross-reactions were remedied promptly by either absorption or dilution of the antisera involved. The MCAP was found to be a rapid and reliable technique for the serological grouping of streptococci.