Postmenopausal onset of androgen excess: a diagnostic and therapeutic algorithm based on extensive clinical experience.

PURPOSE: Postmenopausal hyperandrogenism is a rare condition that requires identifying those women bearing a life-threatening tumor. We aimed to study diagnostic work-up and management of postmenopausal androgen excess, proposing an algorithm for clinical decision supporting. METHODS: We conducted an observational cross-sectional study and longitudinal follow-up including 51 consecutive menopausal patients reported for hyperandrogenism between 2003 and 2023 to our clinics. We assessed diagnostic testing accuracy and performance by receiver operating characteristic curves, their respective areas under the curve (AUCROC), and 95% confidence intervals (95%CI), for distinguishing between benign and malignant conditions, and androgen excess source. RESULTS: Most commonly, postmenopausal hyperandrogenism derived from benign conditions such as ovarian hyperthecosis (n = 9). However, four (8%) patients had borderline/malignant tumors arising at the ovaries (n = 3) or adrenals (n = 1). These latter were more likely to develop virilization than those with benign disorders [specificity(95%CI)]: 0.87 (0.69; 0.92)]. Circulating total testosterone [AUCROC(95%CI): 0.899 (0.795; 1.000)] and estradiol [AUCROC(95%CI): 0.912 (0.812; 1.000)] concentrations showed good performances for discriminating between both conditions. Transvaginal-ultrasonography found two out of three potentially malignant ovarian neoplasms, and another was apparent on a pelvic computed tomography scan. An adrenal computed tomography scan also located an androgen-secreting carcinoma. CONCLUSIONS: Clinical or biochemical features of an aggressive androgen-secreting tumor should lead to urgently obtaining a targeted imaging. At first, an abdominal-pelvic CT scan represents the best choice to perceive adrenal malignancy, and may identify aggressive ovarian tumors. When warning signs are lacking, a calm and orderly work-up allows properly addressing the diagnostic challenge of postmenopausal hyperandrogenism.

Differential transcription profiles in Aedes aegypti detoxification genes after temephos selection.

The mosquito Aedes aegypti is the main vector of Dengue and Yellow Fever flaviviruses. The organophosphate insecticide temephos is a larvicide that is used globally to control Ae. aegypti populations; many of which have in turn evolved resistance. Target site alteration in the acetylcholine esterase of this species has not being identified. Instead, we tracked changes in transcription of metabolic detoxification genes using the Ae. aegypti 'Detox Chip' microarray during five generations of temephos selection. We selected for temephos resistance in three replicates in each of six collections, five from Mexico, and one from Peru. The response to selection was tracked in terms of lethal concentrations. Uniform upregulation was seen in the epsilon class glutathione-S-transferase (eGST) genes in strains from Mexico prior to laboratory selection, while eGSTs in the Iquitos Peru strain became upregulated after five generations of temephos selection. While expression of many carboxyl/cholinesterase esterase (CCE) genes increased with selection, no single esterase was consistently upregulated and this same pattern was noted in the cytochrome P450 monooxygenase (CYP) genes and in other genes involved in reduction or oxidation of xenobiotics. Bioassays using glutathione-S-transferase (GST), CCE and CYP inhibitors suggest that various CCEs instead of GSTs are the main metabolic mechanism conferring resistance to temephos. We show that temephos-selected strains show no cross resistance to permethrin and that genes associated with temephos selection are largely independent of those selected with permethrin in a previous study.

A mutation in the voltage-gated sodium channel gene associated with pyrethroid resistance in Latin American Aedes aegypti.

Pyrethroids are commonly used as mosquito adulticides and evolution of resistance to these compounds is a major threat to public health. 'Knockdown resistance' to pyrethroids (kdr) is frequently caused by nonsynonymous mutations in the voltage-gated sodium channel transmembrane protein (para) that reduce pyrethroid binding. Early detection of kdr is critical to the development of resistance management strategies in mosquitoes including Aedes aegypti, the most prevalent vector of dengue and yellow fever viruses. Brengues et al. described seven novel mutations in hydrophobic segment 6 of domain II of para in Ae. aegypti. Assays on larvae from strains bearing these mutations indicated reduced nerve sensitivity to permethrin inhibition. Two of these occurred in codons Iso1011 and Val1016 in exons 20 and 21 respectively. A transition in the third position of Iso1011 encoded a Met1011 replacement and a transversion in the second position of Val1016 encoded a Gly1016 replacement. We have screened this same region in 1318 mosquitoes in 32 additional strains; 30 from throughout Latin America. While the Gly1016 allele was never detected in Latin America, we found two new mutations in these same codons. A transition in the first position of codon 1011 encodes a Val replacement while a transition in the first position of codon 1016 encodes an Iso replacement. We developed PCR assays for these four mutations that can be read either on an agarose gel or as a melting curve. Selection experiments, one with deltamethrin on a field strain from Santiago de Cuba and another with permethrin on a strain from Isla Mujeres, Mexico rapidly increased the frequency of the Iso1016 allele. Bioassays of F(3) offspring arising from permethrin susceptible Val1016 homozygous parents and permethrin resistant Iso1016 homozygous parents show that Iso1016 segregates as a recessive allele in conferring kdr. Analysis of segregation between alleles at the 1011 and 1016 codons in the F(3) showed a high rate of recombination even though the two codons are only separated by a ~250 bp intron. The tools and information presented provide a means for early detection and characterization of kdr that is critical to the development of strategies for resistance management.

Diversity of surface protein expression in group B streptococcal colonizing & invasive isolates.

BACKGROUND & OBJECTIVES: The classification of group B streptococcal (GBS) isolates is based on the capsular polysaccharides (Ia-VIII), and antigenic characterization of clinical isolates is augmented by the detection of various surface-localized protein antigens. In our laboratory, all GBS isolates are routinely analysed for the alpha trypsin-resistant and the beta trypsin-sensitive c protein antigens, as well as other trypsin-resistant proteins R1, R3, and R4, as well as BPS. The purpose of this work was to study diversity of protein expression in colonizing isolates (vaginal and rectal sites) from nonpregnant women and from invasive isolates (blood or CSF) from mothers and their less than seven day old newborn infants. METHODS: A total of 289 invasive isolates and 2660 colonizing isolates were collected between 1993-2002. All isolates were tested for polysaccharide serotype and cell surface-expressed protein profile by double immunoprecipation in agarose using monospecific antisera. RESULTS: Among the 289 invasive isolates, 89.6 per cent expressed one or more trypsin-resistant proteins; 93 per cent of the colonizing isolates expressed one or more of these proteins. Overall, the most common surface protein expression profile by GBS serotype was: alpha in type Ia; alpha plus beta in type Ib; alpha and R4 in type II; R4 in type III; and co-expression of R1 plus R4 in isolates of type V. BPS was found in five (1.7%) invasive isolates, alone in two isolates and with other proteins in three isolates. Among 2660 colonizing isolates, BPS was found alone in 15 (0.6%) and in 57 additional isolates with other proteins. Among the total isolates, BPS was found predominantly in serotype Ia isolates, also expressing R1. Uncommon protein profiles of known serotypes included 11 type III isolates expressing alpha plus beta. Among 72 nontypable colonizing isolates, expression of R1 plus R4 was the commonest (33.3%) profile. INTERPRETATION & CONCLUSION: The GBS surface proteins and the common serotypes were distributed comparably in colonizing and invasive isolates. Trypsin-resistant, alpha and alpha-like proteins, R1 and R4 were the most prevalent. The phenotypic diversity of the surface-localized protein antigens of GBS is intriguing, and genotypic analysis will permit consensus in nomenclature from laboratory to laboratory.

Characterization of vaginal & rectal colonization with multiple serotypes of group B streptococci using multiple colony picks.

BACKGROUND & OBJECTIVES: There is paucity of information on vaginal and rectal colonization with multiple serotypes of group B streptococci (GBS). As part of an ongoing cohort study evaluating the natural history of vaginal and rectal colonization by GBS, the colonization with multiple serotypes was studied in 102 non-pregnant women aged 18-30 yr. METHODS: Up to ten separate colony picks of beta-haemolytic streptococci (total 1515 isolates) were selected from vaginal and rectal primary culture plates. The colonies were identified as GBS, and their capsular polysaccharides (CPS) serotypes determined using monospecific rabbit antisera for types Ia-VIII by double immunodiffusion in agarose (DID). A colony dot immunoblot (DB) assay, using monospecific rabbit antisera to purified type polysaccharides conjugated to tetanus toxoid, was developed to serotype efficiently the multiple colony picks of GBS. RESULTS: The CPS serotype distribution, examining only the 177 "a" or first colony picks from the 102 patients, was 30.5 per cent for Ia; 28.2 per cent for type III; 15.3 per cent for type II; and 13.6 per cent for type V. Only 2.8 per cent were nontypeable. Eighty of the 102 patients (78.4%) were colonized with only one serotype; 20 (19.6%) had two serotypes and two patients (2%) had three serotypes in their vaginal and/or rectal paired cultures. Overall, 91.9 per cent of the culture sites colonized with one to three CPS types (from the total number of colonies picked) were identified with a minimum of three colony picks. In 75 patients with vaginal/rectal pairs the GBS serotype concordance of only the "a" colony was 89.3 per cent and concordance decreased to 80 per cent when the serotype concordance of the total colony picks was analyzed. INTERPRETATION & CONCLUSION: In conclusion, there was a relatively high prevalence of serotype nonconcordance in this population, and 21.6 per cent of patients had multiple GBS serotypes.

Effect of different densities of the twospotted spider mite Tetranychus urticae on CO2 assimilation, transpiration, and stomatal behaviour in rose leaves.

The effect of population density of Tetranychus urticae Koch on CO2 assimilation, transpiration and stomatal behaviour in rose leaves and on the diameter and length of stems and flower buds was investigated under greenhouse conditions. The investigation was performed in order to gain more insight into integrated control systems in rose crops grown under greenhouse conditions. Physiological processes, such as photosynthesis and transpiration, as well as stomatal behaviour and chlorophyll content, were studied as they form part of the plant's nutrition mechanism and therefore affect the quantity and quality of the flowers. Information related to the effect of spider mite population density on bloom quality, diameter and length of stems and flower buds was also collected. The data indicate that increased mite density coincides with a decrease in the net photosynthetic rate, transpiration and chlorophyll content. Higher mite densities on leaves cause stomata to remain open for longer periods, which allows a greater loss of water. Spider mite densities of 10 and 50 mites per leaf cause a reduction in flower stem length of 17 and 26%, respectively, as compared to plants with no mites present.

3-Methyl-5-hydroxy-5-trichloromethyl-1H-1-pyrazolcarboxyamide induces antinociception.

The antinociceptive action of a novel pyrazole-derived compound, 3-methyl-5-hydroxy-5-trichloromethyl-1H-1-pyrazolcarboxyamide (MPCA) was evaluated using the formalin and tail-immersion tests in mice. Anti-inflammatory activity was assessed by paw plethysmometry in adult rats using the carrageenin-induced paw edema test. Subcutaneous administration of MPCA (22, 66, and 200 mg/kg) induced a dose-dependent decrease in the time spent licking during the neurogenic and inflammatory phases of the formalin test, and preadministration of naloxone (1 mg/kg, sc) did not prevent MPCA-induced (200 mg/kg, sc) antinociception. Naloxone decreased the spontaneous locomotor activity of mice, while MPCA had no effect on locomotion. In contrast, administration of the opioid antagonist caused a significant increase in the locomotor behavior of mice previously injected with MPCA. MPCA was devoid of antinociceptive action by the tail-immersion test and of anti-inflammatory activity. Moreover, MPCA had no effect on the motor performance of mice in the rotarod test. These results suggest that MPCA induces antinociception in the neurogenic and inflammatory phases of the formalin test, an effect that does not involve opioid receptors.

Invasive disease due to group B Streptococcus in pregnant women and neonates from diverse population groups.

From 1993 through 1996, surveillance for invasive disease due to group B Streptococcus (GBS) in neonates aged <7 days and in peripartum pregnant women was performed in a racially and ethnically diverse cohort in 4 cities in the United States. In a birth population of 157,184, 130 neonatal cases (0.8 per 1000) and 54 maternal cases (0.3 per 1000) were identified. Significant correlates with neonatal disease were black or Hispanic race and a birth weight <2500 g. The attack rate for peripartum maternal infection varied widely by city and may have been influenced by the frequency of administration of intrapartum antibiotics or of evaluating febrile women by performance of blood cultures. Pregnancy loss or GBS disease in the infant occurred in 28% of these maternal cases. Among neonatal and maternal GBS isolates, serotypes Ia (34%-37%) and III (25%-26%) predominated, and type V was frequent (14%-23%). These results provide a description of invasive GBS perinatal infection during the period in which guidelines for prevention were actively disseminated.

Bioremediation of MTBE: a review from a practical perspective.

The addition of methyl tert-butyl ether (MTBE) to gasoline has resulted in public uncertainty regarding the continued reliance on biological processes for gasoline remediation. Despite this concern, researchers have shown that MTBE can be effectively degraded in the laboratory under aerobic conditions using pure and mixed cultures with half-lives ranging from 0.04 to 29 days. Ex-situ aerobic fixed-film and aerobic suspended growth bioreactor studies have demonstrated decreases in MTBE concentrations of 83% and 96% with hydraulic residence times of 0.3 hrs and 3 days, respectively. In microcosm and field studies, aerobic biodegradation half-lives range from 2 to 693 days. These half-lives have been shown to decrease with increasing dissolved oxygen concentrations and, in some cases, with the addition of exogenous MTBE-degraders. MTBE concentrations have also been observed to decrease under anaerobic conditions; however, these rates are not as well defined. Several detailed field case studies describing the use of ex-situ reactors, natural attenuation, and bioaugmentation are presented in this paper and demonstrate the potential for successful remediation of MTBE-contaminated aquifers. In conclusion, a substantial amount of literature is available which demonstrates that the in-situ biodegradation of MTBE is contingent on achieving aerobic conditions in the contaminated aquifer.

Inhibition enzyme-linked immunosorbent assay for serotyping of group B streptococcal isolates.

Group B Streptococcus (GBS) is one of the most common organisms causing neonatal sepsis as well as serious infections in adults. Serotyping the organism is important in studying the epidemiology of the disease as well as deciding a course of treatment. There are several methods available for serotyping. Most of them need high-titered sera and are not quantitative. We are reporting a new inhibition enzyme-linked immunosorbent assay (ELISA) for serotyping which is sensitive and specific compared to the conventional methods but does not need high-titered serotype-specific antisera, as the specificity is controlled by the polysaccharide coating on the ELISA plates. The method can also be quantitative, and we have measured polysaccharide elaborated by different serotype V strains. Thus, the inhibition ELISA method will be useful in serotyping for epidemiological studies, assessing virulence, and performing strain selection for vaccine production.

Surface protein expression in group B streptococcal invasive isolates.

Results from characterization of 211 GBS isolates from early-onset disease indicated that serotypes Ia, III and V accounted for almost 80% of the isolates, and that alpha was the protein most often expressed. Each of the common polysaccharide types had a characteristic predominant protein expression pattern: alpha for Ia, R4 for type III and R1+R4 for type V isolates. Expression of alpha protein was always mutually exclusive of R proteins. The presence of more than one species of R by a given isolate was confirmed by IEP. In addition, PAGE/WB studies verified the multiple MW forms of R1, and the variation from strain to strain in the highest form of R4 that we had previously reported. Our data not only showed the great complexity of the GBS cell surface but also demonstrated the advantage of using both type polysaccharides and surface-localized proteins as markers for characterization of GBS strains.

Cloning of the glutamine synthetase gene from group B streptococci.

The glnA gene from the human pathogen Streptococcus agalactiae was cloned from a genomic library prepared with the lambda phage vector lambdaDASHII. A 4.6-kb DNA fragment of one of the recombinant phages was subcloned in pUC18. This Escherichia coli clone expressed a 52-kDa protein encoded by a 1,341-bp open reading frame. The nucleotide sequence of the open reading frame and the deduced amino acid sequence shared a significant degree of homology with the sequences of other glutamine synthetases (GS). The highest homology was between our deduced protein and GS of gram-positive bacteria such as Bacillus subtilis, Bacillus cereus, and Staphylococcus aureus. Plasmids with the cloned streptococcal glnA were able to complement E. coli glnA mutants grown on minimal media. Rabbit antisera to streptococcal GS recombinant protein recognized not only the recombinant protein but also a similar-sized band in mutanolysin extracts of all group B streptococcal strains tested, regardless of polysaccharide type or surface protein profile. The amino acid sequence of the deduced protein had similarities to other streptococcal cell-surface-bound proteins. The possible functional role of the immunological features of streptococcal GS is discussed.

Molecular diversity among the trypsin resistant surface proteins of group B streptococci.

The alpha (alpha) component of the c protein and R proteins are trypsin resistant, but antigenically distinct, proteins on the cell surface of some but not all strains of group B streptococci (GBS). These two classes of proteins, along with the group and type polysaccharide, can be used to characterize strains of GBS. Four species of R protein (R1 through R4) have been described. We studied trypsin extracts from numerous strains of GBS by immunodiffusion in agarose and polyacrylamide gel electrophoresis/Western blot. Sera monospecific for alpha, R1 and R4 were used to immunoprecipitate/blot the proteins. The molecular weight of the blotted proteins was determined. Although by immunodiffusion the proteins within a class were identical to each other, great heterogeneity in size and blotting pattern was found within each class. Variation was independent of the polysaccharide serotype. Multiple molecular weight species were seen for alpha, R1 and R4 proteins. For a given strain, the various forms of alpha or R1 appeared to form a multiple size ladder; those of R4 were fewer and closer in size. The highest form of alpha ranged from 85 to 170 kDa, with 45 kDa being the highest form for some rare GBS strains. For R4 the predominant and highest form varied from 84 to 197 kDa, whereas some strains with R1 had the highest form over 200 kDa. Our results indicated that despite similarities, there is great diversity among the alpha, R1 and R4 trypsin resistant proteins of GBS.

Immune responses to the R4 protein antigen of group B streptococci and its relationship to other streptococcal R4 proteins.

The R antigen, a trypsin-resistant protein observed in group A, C, F, G, and L streptococci, has also been found in group B streptococci (GBS). Although four species of the R antigen have been described for GBS, the R4 protein is the most prevalent in GBS isolates recovered from humans. This study examined the prevalence of antibodies against the R4 antigen by Western blot (immunoblot) (WB) in sera from 40 mothers colonized with GBS serotype II and III and from 26 noncolonized mothers; 92.5% of the colonized mothers had anti-R4 antibodies, compared with 54% of the noncolonized mothers (P < 0.001). Findings of antibodies in neonatal cord sera (n = 14) were concordant with maternal results by WB analysis for 71% of mother-infant pairs colonized with serotype II and for 57% of pairs colonized with serotype III. Of mothers known to be colonized with type II/R4 or III/R4, 100% (n = 12) had antibody against R4 by WB. This study also evaluated the prevalence of antibody to the GBS R4 antigen in 48 sera from individuals with high and low group A streptococcal anti-DNase B titers. Of those individuals with an anti-DNase B titer of > 640, 64% had a positive WB for anti-R4 antibody, compared with 30% of individuals with low anti-DNase B titers (P < 0.05). The R4 antigen of GBS had immunologic identity to the R4 antigen of group A streptococci. Overall, the findings suggested that antibodies to the streptococcal R4 antigen were commonly present in GBS-colonized mothers and that transplacental passage of these antibodies occurred. The presence of antibody to R4 in non-GBS-colonized individuals may be due to immunologic responses to past exposure to the R antigen present in GBS or other streptococcal groups.

Antibody profiles to the group B streptococcal beta antigen in maternal and infant paired sera.

Antibody profiles to the purified beta antigen of the c protein of group B streptococci (GBS) were studied by ELISA and Western immunoblot (WB). The sera from 139 parturient women colonized with GBS, 35 non-colonized parturients and their newborn infants were studied by ELISA; WB was done on 76 maternal and 26 infant sera. Enzyme-labeled anti-IgA (alpha), -IgG (gamma), -IgM (mu), or -IgG (H&L) were used as secondary antibodies. A high prevalence of antibody to the beta antigen was observed by both ELISA and WB among parturient women and their newborns. IgG (H&L) ELISA titers > or = 200 were found in 84% and > or = 800 in 31% of the maternal sera. A significantly higher percentage of women colonized than those non-colonized with GBS had IgG (gamma) titers > or = 800. A significantly higher percentage of women colonized with c protein-positive than c-negative strains of GBS had IgG (H&L) titers > or = 3200. Twelve of 27 women with IgM antibody to the beta antigen also had IgG (gamma) titers > or = 800 and were, in addition, colonized with GBS. Multiple molecular forms of the antigen from 25 to 140 kDa were blotted by the maternal and infant sera. Concordance in the IgG but not in IgA or IgM antibody profiles of maternal and infant paired sera was observed in the overall blotting patterns and ELISA titers. The same titer as the mother was found in 55% of the infant sera and within one dilution in 97%. This suggests active transfer of IgG antibody to the beta antigen across the placenta from mother to baby.

Molecular species of R-protein antigens produced by clinical isolates of group B streptococci.

Clinical isolates of group B streptococci from body fluids and mucosal surfaces were examined for production of a trypsin-resistant antigen known as R protein. R protein was extracted with 1% trypsin from cells grown in a semidefined medium. The extracts were tested by immunodiffusion in agarose with a panel of antisera for detection and precise identification of the four species of R protein described by Wilkinson. R antigen was present in 49 of 131 (37%) of the strains tested. Analysis by serotype revealed that 0 of 2 type Ia, 0 of 11 Ib, 1 of 16 (6%) Ia/c, 12 of 15 (80%) II, 0 of 20 II/c, 35 of 49 (71%) III, 0 of 6 IV, and 1 of 12 (8%) nontypeable strains produced R antigen. Production of the R protein and the trypsin-resistant or alpha component of the c protein appeared to be mutually exclusive. R antigen was more prevalent in isolates from blood (50%) than in those from mucosal sites (27%) for type II strains; no difference was seen for type III strains from these sites. Concordant results were obtained with five paired body fluid-mucosal surface isolates from individual patients and with isolates from 17 mother-baby pairs. The most frequent species of R antigen was R4 (45 of 49), followed by R1 (4 of 49). These two species of R protein were biochemically (trypsin resistant and pepsin sensitive) and immunologically identical to the R-protein antigens produced by prototype strains of groups A, B, and C streptococci.

The type-specific polysaccharide and the R protein antigens of the L-phase from a group B, type III Streptococcus.

The type-specific polysaccharide and the R protein antigens from filtered culture supernatants of the bacterial phase and L-phase of the group B, type III streptococcal strain 76-043 were studied by several immunological methods. In the L-phase of growth, the two antigens were separate and distinct molecules which were found principally in the culture supernatant even on the 254th serial subculture in the cell-wall-defective state. Only trace amounts of these antigens were detected in extracts of L-phase cells. The type III polysaccharide antigens in the supernatant of cultures of the parent bacterium and the L-phase gave reactions of identity in immunodiffusion. Precipitin bands obtained by immunoelectrophoresis (IEP) revealed that the type-specific antigen of the bacterial phase of growth migrated toward the anode, whereas that of the L-phase remained near the antigen well. The R protein antigen in the L-phase supernatant was immunologically identical to the R protein of the supernatant and 1% trypsin-extracted antigens from whole cells of the parent bacterial strain, and other groups A, B and C streptococcal strains sharing a common R antigen. Immunologically, the R antigen appeared to be the species R4. The R protein of the L-phase and bacterial phase cultures was resistant to 5% trypsin but sensitive to 0.5% pepsin at 37 degrees C/2hr. Antiserum prepared in rabbits against L-phase cells contained an antibody reactive with the R protein antigens of the bacterial and L-phase cultures. The soluble, naturally released type III and R protein streptococcal antigens of the L-phase of growth permitted immunological confirmation of its bacterial origin.

Biochemical markers of the penicillin-induced L phase of a group B, type III Streptococcus sp.

The penicillin-induced L phase of growth of the group B, type III streptococcal strain 76-043 was examined for biochemical properties used for the identification of group B streptococci. After numerous serial subcultures in the cell wall-defective state, this stable L phase continued to produce hemolysin, hippuricase, and CAMP factor in addition to the group- and type-specific antigens. Hemolysin production by the L-phase cells was observed on solid and in liquid media containing sheep erythrocytes. Washed whole L-phase cells hydrolyzed hippuric acid. CAMP factor was detected by the characteristic hemolysis produced on blood agar by L-phase cells or filtered culture supernatants. CAMP factor activity was quantitated by an agar well diffusion system and a macrotube assay with partially purified preparations of CAMP factor and staphylococcal beta-hemolysin. Hyperimmune cow serum neutralized the CAMP activity of the L phase and parent bacterial phase to the same degree, suggesting identity of the CAMP factors. Production of hemolysin, hippuricase, and CAMP factor confirmed the bacterial origin of this L phase. Assay for these biological markers could be used to identify L-phase organisms derived from group B streptococci.

Factors influencing antibody responses to streptococcal M proteins in humans.

In a defined population of 174 children followed at one- to two-week intervals for 23 months, the development of M type-specific antibodies to four different types of group. A streptococci was assayed in 408 serum samples from 68 children who acquired one or more of these types in the upper respiratory tract and/or skin lesions. M type 6, a classic pharyngitis strain, was isolated almost exclusively from the upper respiratory tract. Acquisition of this type resulted in the highest percentage of responders without antibody to M protein and in the greatest magnitude of type-specific bactericidal activity as compared with M types 31, 49, and 52, which were commonly associated with pyoderma lesions. Factors that appeared to influence the M type-specific antibody response included the streptococcal type, the age of the child, the number of culture-positive visits, and the stage of the outbreak. The site(s) of isolation by itself and the serum opacity reaction of the infecting strain did not appear to be important determinants of the M type-specific antibody response.