Epidemiological, biochemical and antimicrobial susceptibility characteristics of Streptococcus pseudoporcinus isolated in Quebec, Canada, from 1997 to 2006

Genome analysis of Streptococcus spp. isolates from animals in pre-antibiotic era with respect to antibiotic susceptibility and virulence gene profiles

Lyophilized Streptococcus spp. isolates (n = 50) from animal samples submitted to the diagnostic laboratory at the University of Connecticut in the 1940s were revivified to investigate the genetic characteristics using whole-genome sequencing (WGS). The Streptococcus spp. isolates were identified as follows; S. agalactiae (n = 14), S. dysgalactiae subsp. dysgalactiae (n = 10), S. dysgalactiae subsp. equisimils (n = 5), S. uberis (n = 8), S. pyogenes (n = 7), S. equi subsp. zooepidemicus (n = 4), S. oralis (n = 1), and S. pseudoporcinus (n = 1). We identified sequence types (ST) of S. agalactiae, S. dysgalactiae, S. uberis, S. pyogenes, and S. equi subsp. zooepidemicus and reported ten novel sequence types of those species. WGS analysis revealed that none of Streptococcus spp. carried antibiotic resistance genes. However, tetracycline resistance was observed in four out of 15 S. dysgalactiae isolates and in one out of four S. equi subsp. zooepidemicus isolate. This data highlights that antimicrobial resistance is pre-existed in nature before the use of antibiotics. The draft genome sequences of isolates from this study and 426 complete genome sequences of Streptococcus spp. downloaded from BV-BRC and NCBI GenBank database were analyzed for virulence gene profiles and phylogenetic relationships. Different Streptococcus species demonstrated distinct virulence gene profiles, with no time-related variations observed. Phylogenetic analysis revealed high genetic diversity of Streptococcus spp. isolates from the 1940s, and no clear spatio-temporal clustering patterns were observed among Streptococcus spp. analyzed in this study. This study provides an invaluable resource for studying the evolutionary aspects of antibiotic resistance acquisition and virulence in Streptococcus spp.

Endocarditis with Streptococcus pseudoporcinus Associated with Mastocytosis and Spondylodiscitis-A Coincidental Association? A Case Report

Streptococcus pseudoporcinus is a nonmotile Gram-positive, catalase, and benzidine negative, arranged in short chains, isolated from the genitourinary tract group B Streptococcus. S. pseudoporcinus was also identified from blood, urine, skin, cervical area, wounds, rectum, and placenta samples. Two cases of infective endocarditis have been reported in the literature. Based on these data, the identification of a case of S. pseudoporcinus infective endocarditis associated with spondylodiscitis in a patient with undiagnosed systemic mastocytosis until the age of 63 years is unusual. Two sets of blood specimens were collected, and both sets were positive for S. pseudoporcinus. Transesophageal echocardiography revealed, multiple vegetations on the mitral valve. A lumbar spine MRI revealed L5-S1 spondylodiscitis that associates prevertebral and right paramedian epidural abscesses with compressive stenosis. The performed bone marrow biopsy, and cellularity examination revealed 5-10% mast cells in the areas of medullary tissue, an aspect that is suggestive of mastocytosis. Antibiotic therapy was initiated, under which the patient presented intermittent fever. A second transesophageal echocardiography revealed a mitral valve abscess. A mitral valve replacement with a mechanical heart valve device through a minimally invasive approach was performed, with a favorable evolution under treatment. S. pseudoporcinus can be responsible for infectious endocarditis in certain immunodepressed cases, but also in a profibrotic, proatherogenic field, as shown by the association with mastocytosis in the presented case.

Case report: Multidrug-resistant Streptococcus pseudoporcinus isolated from an infected surgical wound of a 9-year-old spayed female Great Dane dog

Streptococcus pseudoporcinus (S. pseudoporcinus) is a β-hemolytic, Gram-positive novel bacterium first identified in 2006. It is a catalase-negative, non-motile coccus arranged in short chains. Furthermore, it has a broad beta-hemolytic reaction on sheep blood agar and cross-reacts with Lancefield group B antigen agglutination reagent. In this study, we report a case of S. pseudoporcinus infection of a surgical wound on the left metatarsus of a dog. The patient is a 9-year-old spayed female Great Dane dog with a brief history of multiple cutaneous masses being removed. Post-surgery, the post-surgical site on the left metatarsus became infected and discharged purulent material with a fetid odor. Upon preliminary diagnostic testing, we detected catalase-negative Gram-positive cocci exhibiting beta-hemolytic growth on sheep blood agar. A VITEK^® 2 Compact machine from bioMérieux identified the bacterium as S. pseudoporcinus. Furthermore, antibiotic testing revealed multidrug resistance. Therefore, we document a multidrug-resistant S. pseudoporcinus isolate as a cause of canine post-surgical wound infection. Furthermore, it was the only isolate detected from the sample; hence, it is the cause of the infection. To our knowledge, this case is the first report of S. pseudoporcinus in a dog.

Case Report: Corneal perforation secondary to orbital cellulitis caused by Streptococcus pseudoporcinus infection

INTRODUCTION

This report described a rare case of corneal perforation secondary to orbital cellulitis caused by Streptococcus pseudoporcinus (S. pseudoporcinus) infection. To the best of our knowledge, only six cases of S. pseudoporcinus infection have been reported. This case report suggested that S. pseudoporcinus infection was contagious and potentially life threatening. The report emphasized the value of managing infections early to avoid serious consequences.

CASE DESCRIPTION

A patient with orbital cellulitis, which progressed to corneal perforation was admitted to the hospital for right facial swelling, pain, and decreased vision in his right eye. S. pseudoporcinus infection was found after bacterial culture of pus puncture. After aggressive anti-infection and surgical treatment, the infection was eliminated, and the patient was discharged. However, the patient had sustained permanent vision loss.

CONCLUSIONS

This case suggested the potential risk of corneal perforation and orbital cellulitis caused by S. pseudoporcinus infection in humans. The specific biological changes and mode of action of S. pseudoporcinus are unclear and need further investigation.

Fatal Streptococcus pseudoporcinus disseminated infection in decompensated liver cirrhosis: a case report

Background

Streptococcus pseudoporcinus (S. pseudoporcinus) was first identified in 2006. It cross-reacts with Lancefield group B antigen agglutination reagents and has been misidentified as S. agalactiae. Sites of S. pseudoporcinus isolation include the female genitourinary tract, urine, wounds, and dairy products. The prevalence of vaginal colonization is reportedly between 1 and 5.4%. Two uneventful cases of soft tissue infection caused by S. pseudoporcinus were reported in the past. However, since late 2019, six cases of invasive S. pseudoporcinus infections have emerged in the literature, one of which was fatal.

Case presentation

We describe a fatal case of a Caucasian male with spontaneous bacterial peritonitis associated with bacteremia due to a multidrug-resistant S. pseudoporcinus strain in a patient with decompensated liver cirrhosis. Despite the patient’s good general condition and stable blood test results when he had visited the outpatient clinic for large-volume paracentesis a few days before admission, this time he presented to the emergency department with a rapidly worsening clinical condition and with laboratory features consistent with multiple-organ dysfunction syndrome, and succumbed within a short period.

Conclusions

Contrary to what was thought until recently, multidrug-resistant S. pseudoporcinus may cause invasive, disseminated, fatal disease in humans. According to current limited data, vancomycin, linezolid, daptomycin, levofloxacin, clindamycin, and tetracycline seem to be the most effective antimicrobial agents against multidrug-resistant strains, and should be the empirical choice in cases of disseminated S. pseudoporcinus infection until laboratory antimicrobial susceptibility results are available. Improvements and new approaches for bacterial identification in routine clinical microbiology laboratories may reveal the real spectrum of S. pseudoporcinus infections in humans, which is currently believed to be underestimated. SS. pseudoporcinus could emerge as a serious medical problem in the near future, similar to other β-hemolytic streptococci.

Una neumonía complicada por un germen inusual: Reporte de caso

El Streptococcus pseudoporcinus es un germen de la clasificación Beta hemolítico, con similitud a Streptococcus agalactiae, con baja incidencia en producción de infección pero principalmente aislado en tracto genitourinario de mujeres embarazadas y relacionado con complicaciones materno-fetales. Reportes en la literatura como infección fuera de este sitio son inusuales, por lo cual presentamos un caso de un hombre de 48 años con infección de tracto respiratorio bajo, compatible con colección neumónica y un derrame paraneumonico complicado, con requerimiento de manejo antibiótico y drenaje por toracostomia. Al realizar el estudio microbiológico se reportó aislamiento de un Streptococcus pseudoporcinus. No hay reportes previos en la literatura como causa de infección en este sitio anatómico.

Isolation and characteristics of multi-drug resistant Streptococcus porcinus from the vaginal secretions of sow with endometritis

Background

Sow endometritis is a common disease in pig breeding farms after artificial insemination, which leads to gray-green vaginal secretions and decreased conception rates. It is important to perform an etiologic diagnosis for effective treatments and control of diseases. The aim of this study was to carry out a pathogenic detection in five specimens of vaginal secretions collected from sick pigs with endometritis, implement identification of the pathogens by phenotypic detection and 16 s rDNA sequence and phylogeny analysis, and determinate antibiotic susceptibility of the isolates.

Results

A Streptococcus strain was isolated and identified from all of the five specimens. The isolate was positive for Voges-Proskauer (V-P) and for the hydrolysis of arginine, esculin and myelin-associated glycoprotein (MAG). Acid formation was observed for sorbitol, mushroom sugar, sucrose, and glucose. The 16S rDNA sequence of the isolate possessed 99.93% similarity to that of Streptococcus porcinus. The phylogenetic analysis of 16S rDNA sequence showed that the isolate belonged to the same clade as the S. porcinus strains from humans, pigs, and other animals. The isolate exhibited multi-drug resistance to aminoglycosides, quinolones, macrolides and tetracyclines except being sensitive to some β- lactams such as penicillin G, cephalothin, cefazolin, cephradine and cefuroxime.

Conclusions

A S. porcinus isolate with multi-drug resistance was identified from vaginal secretions of sows with endometritis in one pig breeding farm, which suggests that the sow endometritis was caused by S. porcinus infection during artificial insemination. This study indicates that sensitive antibiotics such as penicillin G or some cephalosporins could be used for treatment of the diseases. In addition, the study hints that bacterial multi-drug resistance is a tough problem for disease treatment in pig farms.

Streptococcus pseudoporcinus: Case Reports and Review of the Literature

Streptococcus pseudoporcinus is a beta-hemolytic Gram-positive, catalase-negative, nonmotile coccus arranged in short chains, usually found in the female genitourinary tract and differentiated from Streptococcus porcinus in 2006. Only two human infections associated with this organism have been reported to date: one in a patient with a first digit wound infection and another with lower extremity cellulitis. We describe two novel cases of Streptococcus pseudoporcinus causing endocarditis in one and pneumonia with empyema in another, illustrating the potential of these bacteria to cause severe invasive and life-threatening disease.

First report of infective endocarditis caused by Streptococcus pseudoporcinus in Vietnam

We report a first case of Streptococcus pseudoporcinus bacteraemia causing infective endocarditis in a 40-year-old man in Vietnam. This is the second case of Streptococcus pseudoporcinus infective endocarditis in the literature. The patient was successfully treated by antibiotics, combined with aortic valve replacement. Streptococcus pseudoporcinus may be an emerging infectious agent causing endocarditis.

A Case of Maternal Sepsis and Fetal Demise Associated with Streptococcus pseudoporcinus

Streptococcus pseudoporcinus has recently been described in relation to its colonization of the female genitourinary tract. Since prior reports have linked S. pseudoporcinus only with minor morbidities, the organism previously has not been considered to be a cause of serious puerperal infections. A 41-year-old gravida 2, para 1-0-0-1 presented with abdominal pain and intrauterine fetal demise. A beta hemolytic Streptococcus was isolated from her placenta, endometrium, urine, and two blood culture sets. The isolate was a Streptococcus pseudoporcinus, which colonizes the female genital tract and can resemble Streptococcus agalactiae. This case demonstrates that S. pseudoporcinus is a potential cause of severe maternal and fetal morbidity and mortality.

Differentiating Streptococcus pseudoporcinus from GBS: could this have implications in pregnancy?

BACKGROUND

Streptococcus agalactiae (GBS) is a common pathogen known to cause neonatal and maternal infectious morbidity. Streptococcus pseudoporcinus (S pseudoporcinus) is a separate, recently identified β-hemolytic gram-positive coccus that can cause false-positive results on standard GBS agglutination testing assays.

OBJECTIVE

To determine the prevalence and clinical implications of Streptococcus pseudoporcinus colonization in pregnancy.

MATERIALS AND METHODS

This is a 2-year retrospective cohort study comparing pregnant women colonized with GBS to those colonized with S. pseudoporcinus. A proteomics method of identification, namely, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, was used to distinguish between S. pseudoporcinus and GBS colonization. Antibiotic susceptibility testing was carried out on all specimens. Maternal and neonatal chart reviews were conducted to identify predictors of S. pseudoporcinus colonization and to compare maternal and neonatal outcomes.

RESULTS

S. pseudoporcinus colonization occurred in 1.6% of all pregnancies. A total of 2.5% of all GBS-positive results by agglutination assay were false positive, instead reflecting S. pseudoporcinus colonization. Clindamycin resistance among S. pseudoporcinus isolates is uncommon. S. pseudoporcinus colonization in pregnancy is independently associated with African American race, tobacco use, and body mass index ≥35. Preterm premature rupture of membranes or spontaneous preterm birth was more common in patients colonized with S. pseudoporcinus.

CONCLUSION

Although the prevalence of S. pseudoporcinus colonization is low, it primarily occurs in African American women and is associated with preterm premature rupture of membranes or spontaneous preterm birth when compared to individuals colonized with GBS.

Antibiotic susceptibility, cytotoxicity, and protease activity of viridans group streptococci causing endophthalmitis

The viridans group streptococci comprise multiple species and have gained more recognition in recent years as common etiologic agents of bacterial endophthalmitis. The purpose of this study was to identify the species of human endophthalmitis isolates of viridans streptococci and to characterize their potential virulence attributes. The species of 22 endophthalmitis strains of viridans streptococci were identified by Matrix Assisted Laser Desorption Ionization Time-of-Flight. Susceptibilities to 3 antibiotics commonly used for bacterial endophthalmitis were determined. The extracellular milieu of each strain was tested for cytotoxicity of retinal pigmented epithelial cells, hemolysis of sheep erythrocytes, and protease activity using gelatin zymography. Identified species were Streptococcus mitis/oralis, S. salivarius, S. vestibularis, S. parasanguinis, S. mutans, S. constellatus, and S. gordonii. One strain of S. pseudoporcinus was also identified. All strains were sensitive to vancomycin, 77% were resistant to amikacin, and 27% had intermediate resistance to ceftazidime. Extracellular milieu from all strains except one (S. pseudoporcinus) were largely devoid of toxicity to retinal pigmented epithelial cells and sheep erythrocytes. Twelve strains, 10 of which were S. mitis/oralis, produced protease activity. Interestingly, not all of the S. mitis/oralis strains were proteolytic. These findings highlight the diversity of virulence factor production in ocular strains of the viridans streptococci not only at the group level but also at the species level.

A case of leg cellulitis caused by multidrug-resistant Streptococcus pseudoporcinus

A 94-year-old woman was admitted to our hospital with a 5-day history of painful redness in the left lower leg. She was diagnosed with cellulitis and initiated antibiotic therapy with cefazolin. After two days, she presented with an extremely high fever (39.9°C), high C-reactive protein level (256 mg/L; normal, < 3), and signs of disseminated intravascular coagulation. In bacteriological examination, Streptococcus pseudoporcinus was detected from her lower leg wound purulence. An antibiogram revealed multidrug resistance except for cefepime, carbapenems, and vancomycin. We changed the antibiotics to cefepime and vancomycin according to the antibiogram and administered immunoglobulin concurrently. As the result of these therapies, her conditions gradually resolved over two weeks. S. pseudoporcinus, one of the β-hemolytic Streptococcus species recently described, has been isolated from the genitourinary tract of women. To our knowledge, this is the first case of cellulitis caused by S. pseudoporcinus. Typically, most antibiotics indicate adequate drug susceptibilities of S. pseudoporcinus, but in our case, multidrug resistance contributed to the prolonged duration of treatment. Because the colonization of S. pseudoporcinus in healthy individuals is not rare, it could become an important pathogen in elderly people and in those who have underlying medical conditions, as with other β-hemolytic Streptococci.

Detection of Streptococcus agalactiae by immunochromatography with group B streptococcus-specific surface immunogenic protein in pregnant women

BACKGROUND

Infection with Streptococcus agalactiae (Group B streptococcus: GBS) is a significant cause of morbidity and mortality in neonates. Screening for GBS is mainly done by culture-based methods, but a reliable result may take several days to obtain and culture is difficult to perform at institutions without a laboratory. We evaluated an immunochromatography method for rapid detection of GBS-specific surface immunogenic protein (Sip) using anti-Sip monoclonal antibodies.

MATERIALS AND METHODS

A total of 377 cervical and vaginal swabs collected during weeks 35-37 of gestation were inoculated into GBS medium F and incubated. Growth of microorganisms and production of red/orange pigment were assessed by observation. Then culture extracts were subjected to immunochromatography and were also inoculated onto chromID Strepto B (STRB) medium, after which isolates were serotyped and characterized by PCR.

RESULTS

Of the 377 samples, 54 (14.3%) were positive for GBS by immunochromatography after incubation in GBS medium F. On the other hand, GBS was isolated from 58 (15.4%) of the 377 samples by culture with GBS medium F and STRB medium. Ten of the 58 isolates were non-pigmented and 4 of these were not detected by immunochromatography. The sensitivity, specificity, positive predictive value, and negative predictive value of immunochromatography were 93.1% (54/58), 100% (319/319), 100% (54/54), and 98.8% (319/323), respectively.

CONCLUSIONS

Immunochromatography was comparable to culture on STRB medium for detecting GBS, indicating that this method could be used clinically for GBS screening in pregnant women even at small institutions.

Recognition of Streptococcus pseudoporcinus Colonization in Women as a Consequence of Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Group B Streptococcus Identification

During a 14-month period of using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for group B streptococcus (GBS) identification, we recovered 32 (1%) Streptococcus pseudoporcinus isolates from 3,276 GBS screening cultures from female genital sources (25 isolates from pregnant women and 7 from nonpregnant women). An additional two S. pseudoporcinus isolates were identified from a urine culture and a posthysterectomy wound culture. These isolates were found to cross-react with three different GBS antigen agglutination kits, PathoDx (Remel) (93%), Prolex (Pro-Lab Diagnostics) (38%), and Streptex (Remel) (53%). New approaches to bacterial identification in routine clinical microbiology laboratories may affect the prevalence of S. pseudoporcinus.

Immunochromatographic detection of the group B streptococcus antigen from enrichment cultures

Group B Streptococcus (GBS; Streptococcus agalactiae) is a leading cause of serious neonatal infections. The Centers for Disease Control and Prevention recommends GBS screening for all pregnant women during the 35th to 37th weeks of gestation. Although GBS screening has been performed mainly by the culture-based method, it takes several days to obtain a reliable result. In this study, we developed a rapid immunochromatographic test (ICT) for the detection of GBS-specific surface immunogenic protein in 15 min using an overnight enrichment culture. The ICT was prepared using two anti-Sip monoclonal antibodies. This ICT was able to detect recombinant Sip levels of 0.5 ng/ml, or about 10(6) CFU/ml of GBS cells, in tests with 9 GBS strains of different serotypes. The cross-reactivity test using 26 species of microorganism showed no detectable false-positive result. Reactivity of the ICT with 229 GBS strains showed one false-negative result that was attributable to the production of truncated Sip. Among 260 enrichment cultures of vaginal swabs, 17 produced red to orange pigments in Granada medium, and they were all GBS and Sip positive. Among 219 pigment-negative cultures, 12 were GBS positive and 10 were Sip positive. Two Sip-negative cultures contained GBS cells below the limit of detection by the ICT. Among 207 GBS-negative cultures, only one was Sip positive, which was attributable to GBS cell debris. Thus, the sensitivity and specificity of the ICT appeared to be 93.1% and 99.6%, respectively. The newly developed ICT is readily applicable to clinical use in the detection of GBS.

Evaluation of methods for identification and determination of the taxonomic status of strains belonging to the Streptococcus porcinus-Streptococcus pseudoporcinus complex isolated from animal, human, and dairy sources

Ninety-seven animal, human, and dairy Streptococcus porcinus or Streptococcus pseudoporcinus isolates in the CDC Streptococcus strain collection were evaluated on the basis of DNA-DNA reassociation, 16S rRNA and rpoB gene sequencing, conventional biochemical and Rapid ID 32 Strep identification methods, and antimicrobial susceptibility testing to determine their taxonomic status, characteristics for species differentiation, antimicrobial susceptibility, and relevance of clinical source. Nineteen of the 97 isolates (1 human, 18 swine) were identified as S. porcinus. The remaining 72 human isolates and 6 dairy isolates were identified as S. pseudoporcinus. The use of 16S rRNA or rpoB gene sequencing was required to differentiate S. porcinus from S. pseudoporcinus. The human and dairy S. pseudoporcinus isolates were biochemically distinct from each other as well as distinct by 16S rRNA and rpoB gene sequencing. Therefore, we propose the subspecies denominations S. pseudoporcinus subsp. hominis subsp. nov. for the human isolates and S. pseudoporcinus subsp. lactis subsp. nov. for the dairy isolates. Most strains were susceptible to the antimicrobials tested, with the exception of tetracycline. Two strains of each species were also resistant to clindamycin and erythromycin and carried the erm(A) (S. pseudoporcinus) or the erm(B) (S. porcinus) gene. S. porcinus was identified from a single human isolate recovered from a wound in an abattoir worker. S. pseudoporcinus was primarily isolated from the genitourinary tract of women but was also associated with blood, placental, and wound infections. Isolates reacting with group B antiserum and demonstrating wide beta-hemolysis should be suspected of being S. pseudoporcinus and not S. agalactiae.

Incidence and epidemiology of Streptococcus pseudoporcinus in the genital tract

Streptococcus pseudoporcinus, a beta-hemolytic microorganism first isolated from the female gastrourinary tract in 2006, cross-reacts with serogrouping kits for group B Streptococcus (GBS) and could be misidentified in the laboratory. The epidemiologic characteristics of this species have not been reported previously, but this organism is thought to be rare. Paired vaginal and rectal samples were collected from 663 nonpregnant women enrolled in a phase II clinical vaccine trial of a GBS type III capsular polysaccharide-protein conjugate vaccine, and isolates initially identified as S. pseudoporcinus were collected for further testing. A total of 120 isolates of S. pseudoporcinus were recovered from 36 unique individuals with 5.4% of 663 women having this organism recovered at least once during follow-up. All of these isolates cross-reacted with a commercially available GBS serogrouping kit. Women colonized with isolates confirmed as S. pseudoporcinus by genotypic and phenotypic methodologies were compared to women who were not colonized to determine whether there were any significant factors associated with acquisition of S. pseudoporcinus. Acquisition of S. pseudoporcinus vaginally and/or rectally was 36 per 846.0 women-years of follow-up for an annual incidence of 4 per 100 woman-years of follow-up. Acquisition of S. pseudoporcinus was independently associated with black women, being 30 to 40 years of age, recent Trichomonas vaginalis infection, primary or recurrent genital herpes, having bacterial vaginosis by Nugent criteria, and having had two or more male sexual partners since the last visit. This study suggests that S. pseudoporcinus is not rare, especially among black women, and could be misidentified as GBS.

Evaluation of a new chromogenic medium (StrepB select) for detection of group B Streptococcus from vaginal-rectal specimens

We compared StrepB Select medium (Select) after enrichment with conventional culture for the detection of Group B Streptococcus (GBS). Postenrichment sensitivities of Select and conventional culture were 98.8% and 92.2%, respectively (P<0.05). Select was superior for detection of GBS from vaginal-rectal specimens. Growth of non-GBS colonies required additional work to exclude the presence of GBS, especially after 48 h of incubation. Incubation of Select beyond 24 h did not significantly increase the yield of GBS.

Thumb infection caused by Streptococcus pseudoporcinus

Streptococcus pseudoporcinus, a recently described organism found in the genitourinary tract of women, was isolated from a thumb wound in a male patient subsequent to trauma. This case describes a rarely reported non-genitourinary tract clinical isolate of S. pseudoporcinus.