IL-10 and TGF-ß1 may weaken the efficacy of preoperative anti-tuberculosis therapy in older patients with spinal tuberculosis.

Spinal tuberculosis is a common extrapulmonary type that is often secondary to pulmonary or systemic infections. Mycobacterium tuberculosis infection often leads to the balance of immune control and bacterial persistence. In this study, 64 patients were enrolled and the clinicopathological and immunological characteristics of different age groups were analyzed. Anatomically, spinal tuberculosis in each group mostly occurred in the thoracic and lumbar vertebrae. Imaging before preoperative anti-tuberculosis therapy showed that the proportion of abscesses in the older group was significantly lower than that in the younger and middle-aged groups. However, pathological examination of surgical specimens showed that the proportion of abscesses in the older group was significantly higher than that in the other groups, and there was no difference in the granulomatous inflammation, caseous necrosis, inflammatory necrosis, acute inflammation, exudation, granulation tissue formation, and fibrous tissue hyperplasia. B cell number was significantly lower in the middle-aged and older groups compared to the younger group, while the number of T cells, CD4+ T cells, CD8+ T cells, macrophages, lymphocytes, plasma cells, and NK cells did not differ. Meaningfully, we found that the proportion of IL-10 high expression and TGF-ß1 positive in the older group was significantly higher than that in the younger group. TNF-α, CD66b, IFN-γ, and IL-6 expressions were not different among the three groups. In conclusion, there are some differences in imaging, pathological, and immune features of spinal tuberculosis in different age groups. The high expression of IL-10 and TGF-ß1 in older patients may weaken their anti-tuberculosis immunity and treatment effectiveness.

Avid 68Ga-PSMA Uptake in Periappendicular Abscess.

Ga-prostate-specific membrane antigen (PSMA) PET/CT for primary staging of high-risk prostate cancer revealed increased Ga-PSMA uptake in a known periappendicular abscess in a patient, who had undergone surgical drainage of the abscess 1 month earlier. The case presents another example of Ga-PSMA uptake in a benign infectious and inflammatory condition.

[A muscular calcium pyrophosphate deposition pseudo-abscess: An atypical localization of chondrocalcinosis]. / Pseudo-abcès musculaire d'origine microcristalline : une localisation exceptionnelle de chondrocalcinose.

INTRODUCTION: Chondrocalcinosis results from calcium pyrophosphate crystals deposition in the joints. We report an exceptional case of aseptic psoas abscess with a deposition of calcium pyrophosphate crystals. CASE REPORT: A 92-year-old man presented to our department for an acute onset of inflammatory pain in the left hip. Computed tomography detected a coxofemoral arthritis and multiple intramuscular collections located in the iliopsoas muscle and the gluteus minimus. A sample of the fluid was obtained with a guided aspiration, and its analysis revealed an inflammatory liquid with no bacteria but numerous calcium pyrophosphate crystals. The final diagnosis was thus a muscular calcium pyrophosphate deposition pseudo-abscess, associated with a hip arthritis. CONCLUSION: Hip chondrocalcinosis is unusual, and the association with intramuscular deposition of calcium pyrophosphate crystals seems extremely rare as we found only four other published cases. A microcrystalline arthritis could have spread from the coxofemoral joint through the iliopsoas bursa and into the muscle. However, the imaging aspect with an abscess and a predominant muscular injury might suggest a mechanism of crystal formation originating directly within the muscle. The outcome was always favourable even if some patients required surgery.

Porphyromonas gingivalis hydrogen sulfide enhances methyl mercaptan-induced pathogenicity in mouse abscess formation.

Porphyromonas gingivalis produces hydrogen sulfide (H2S) from l-cysteine. However, the role of H2S produced by P. gingivalis in periodontal inflammation is unclear. In this study, we identified the enzyme that catalyses H2S production from l-cysteine and analysed the role of H2S using a mouse abscess model. The enzyme identified was identical to methionine γ-lyase (PG0343), which produces methyl mercaptan (CH3SH) from l-methionine. Therefore, we analysed H2S and CH3SH production by P. gingivalis W83 and a PG0343-deletion mutant (ΔPG0343) with/without l-cysteine and/or l-methionine. The results indicated that CH3SH is produced constitutively irrespective of the presence of l-methionine, while H2S was greatly increased by both P. gingivalis W83 and ΔPG0343 in the presence of l-cysteine. In contrast, CH3SH production by ΔPG0343 was absent irrespective of the presence of l-methionine, and H2S production was eliminated in the absence of l-cysteine. Thus, CH3SH and H2S production involves different substrates, l-methionine or l-cysteine, respectively. Based on these characteristics, we analysed the roles of CH3SH and H2S in abscess formation in mice by P. gingivalis W83 and ΔPG0343. Abscess formation by P. gingivalis W83, but not ΔPG0343, differed significantly in the presence and absence of l-cysteine. In addition, the presence of l-methionine did not affect the size of abscesses generated by P. gingivalis W83 and ΔPG0343. Therefore, we conclude that H2S produced by P. gingivalis does not induce inflammation; however, H2S enhances inflammation caused by CH3SH. Thus, these results suggest the H2S produced by P. gingivalis plays a supportive role in inflammation caused by methionine γ-lyase.

Comparison of Salivary Antioxidants in Children with Primary Tooth Abscesses before and after Treatment in Comparison with Healthy Subjects

Aim: The aim of this study was to compare the total antioxidant capacity (TAC) of children with primary molar abscesses before and two weeks after extraction of the infected tooth. Materials and methods: Forty one children aged between 3-6 years participatesd in this cross sectional study. The antioxidant activity of saliva was investigated in 20 patients with tooth abscesses affecting one of the first primary molars before and after tooth extraction in the case group and once in 21 children with no caries or dental problems in the control group. The FRAP (ferric reduction antioxidant power) method was used to measure the antioxidant power of salivary samples and TAC values were calculated. Data were analyzed with SPSS Version 16 using the paired t-test at a significance level of 0.05. Results: The mean antioxidant index increased in children after (509.2 ± 138.4) treatment (before 483.4 ± 183.6), but this difference was not significant (P=0.61). Also, there was no difference in the mean antioxidant index in control group (494.5±147.9) compared the study group before (P=0.83) and after (P=0.75) treatment. Conclusion: Under the conditions of this study the total antioxidant capacity of saliva was not compromised in children with abscessed teeth.

MyD88 in macrophages is critical for abscess resolution in staphylococcal skin infection.

When Staphylococcus aureus penetrates the epidermis and reaches the dermis, polymorphonuclear leukocytes (PMLs) accumulate and an abscess is formed. However, the molecular mechanisms that orchestrate initiation and termination of inflammation in skin infection are incompletely understood. In human myeloid differentiation primary response gene 88 (MyD88) deficiency, staphylococcal skin and soft tissue infections are a leading and potentially life-threatening problem. In this study, we found that MyD88-dependent sensing of S. aureus by dermal macrophages (Mϕ) contributes to both timely escalation and termination of PML-mediated inflammation in a mouse model of staphylococcal skin infection. Mϕs were key to recruit PML within hours in response to staphylococci, irrespective of bacterial viability. In contrast with bone marrow-derived Mϕs, dermal Mϕs did not require UNC-93B or TLR2 for activation. Moreover, PMLs, once recruited, were highly activated in an MyD88-independent fashion, yet failed to clear the infection if Mϕs were missing or functionally impaired. In normal mice, clearance of the infection and contraction of the PML infiltrate were accompanied by expansion of resident Mϕs in a CCR2-dependent fashion. Thus, whereas monocytes were dispensable for the early immune response to staphylococci, they contributed to Mϕ renewal after the infection was overcome. Taken together, MyD88-dependent sensing of staphylococci by resident dermal Mϕs is key for a rapid and balanced immune response, and PMLs are dependent on intact Mϕ for full function. Renewal of resident Mϕs requires both local control of bacteria and inflammatory monocytes entering the skin.

Zinc, copper, and selenium tissue levels and their relation to subcutaneous abscess, minor surgery, and wound healing in humans.

Trace element involvement in wounds left to heal by secondary intention needs clarification. We have previously reported faster healing of wounds following acute surgery compared with elective excision of pilonidal sinus disease. The effect of topical zinc on the closure of the excisional wounds was mediocre compared with placebo. In contrast, parenteral zinc, copper, and selenium combined appear effective for wound healing in humans. We have investigated zinc, copper, and selenium with respect to (a) impact of acute versus chronic pilonidal sinus and (b) regional concentrations within granulating wounds treated topically with placebo or zinc in 42 (33 males) pilonidal disease patients. Baseline serum and skin concentrations of copper correlated (r S = 0.351, p = 0.033, n = 37), but not of zinc or selenium. Patients with abscesses had elevated serum C-reactive protein (CRP) and copper levels (+29 %; p < 0.001) compared with the elective patients consistent with the strong correlation between serum copper and CRP (r S = 0.715, p < 0.0005, n = 41). Seven days after elective surgery, serum CRP and copper levels were elevated (p = 0.010) versus preoperative values. The copper concentration in wound edges was higher than in periwound skin (p < 0.0005) and wound base (p = 0.010). Selenium levels were increased in wound edge compared to wound base (p = 0.003). Topical zinc oxide treatment doubled (p < 0.050) zinc concentrations in the three tissue localizations without concomitant significant changes of copper or selenium levels. In conclusion, copper and selenium are mobilized to injured sites possibly to enhance host defense and early wound healing mechanisms that are complementary to the necessity of zinc for matrix metalloproteinase activity.

LIPOCALIN-2 is a major acute-phase protein in a rat and mouse model of sterile abscess.

Lipocalin-2 (LCN-2) is a 25-kDa secretory protein currently used as a biomarker for renal injury and inflammation. Its source and cause of the increased serum levels are unclear. The current study compares LCN-2 gene expression with known major acute-phase proteins in the liver in a rat and mouse model of turpentine oil-induced sterile abscess. Serum LCN-2 concentrations increased dramatically up to 200-fold (20 µg/mL) at 48 h after turpentine oil injection. A strong elevation of LCN-2 mRNA in rat liver was observed starting from 4 h up to 48 h after injection, with a maximum (8,738 ± 2,104-fold) at 24 h, which was further confirmed by Western blot analysis. In contrast, the increases in gene expression of α2-macroglobulin, the major acute-phase protein, and hemoxygenase 1, a positive acute-phase protein, were only 1,025 ± 505-fold and 47 ± 12-fold, respectively, during acute-phase reaction (APR). No considerable change was observed in LCN-2 mRNA in rat kidney and other organs as compared with liver. Using wild-type mice, a massive increase in gene expression of LCN-2, with a maximum of 2,498 ± 84-fold in liver, which is similar to that for serum amyloid A (2,825 ± 233-fold), a major mouse acute-phase protein. However, such an increase was significantly inhibited in interleukin 6 knockout mice during APR. Interleukin 6-treated rat hepatocytes induced a significant time-dependent upregulation of LCN-2.Lipocalin-2 is the major acute-phase protein in rat as compared with α2-macroglobulin and hemoxygenase 1 and comparable with serum amyloid A in mouse whose gene expression is mainly controlled by interleukin 6. The liver is the main source of serum LCN-2 in the case of APR. ABBREVIATIONS-LCN-2-lipocalin-2-α2M-α2-macroglobulin-HO-1-hemoxygenase 1-IL-6-interleukin 6-SAA-serum amyloid A-TO-turpentine oil-APR-acute-phase reaction.

Extraovarian conditions mimicking ovarian cancer: a single center experience of 15 years.

OBJECTIVE: This study aims to review cases of extra-ovarian conditions that resembled ovarian malignancy and thus, to evaluate the distribution of primary pathology mimicking ovarian malignancy. METHODS: A retrospective review of women, with final pathology of extra-ovarian diseases mimicking ovarian malignancy, which were managed at Zekai Tahir Burak Women's Health Education and Research Hospital, from January 1995 to April 2010 was undertaken. RESULTS: Among the 2,210 women treated during the study period, extra-ovarian diseases accounted for 5.11% (113/2,210) of all the cases. Of the 113 extra-ovarian diseases, 42 (37.17%) were peritoneal tuberculosis, 25 (22.13%) were gastrointestinal malignancies, 20 (17.70%) were pelvic abscess, 8 (7.08%) were pelvic echinococcosis, 8 (7.08) were schwannoma and other retroperitoneal tumors, 4 (3.53%) were malignant lymphoma, 2 (1.77%) were chronic ectopic pregnancy, gossypiboma, and mesenteric cyst, respectively. CONCLUSION: Medical awareness of infectious diseases such as peritoneal tuberculosis, pelvic abscess, and pelvic echinococcosis in the differential diagnosis of ovarian malignancy is still lacking, especially in developing countries. In addition, in case of a pelvic mass, gastrointestinal and retroperitoneal tumors and malignant lymphoma should always be considered to avoid pitfalls in diagnosis and therapy.

[(18)F-labeled tyrosine derivatives: synthesis and experimental studies on accumulation in tumors and abscesses].

Tyrosine derivatives labeled with a short-living fluorine 18 isotope (T(1/2) 110 min), namely 2-[(18)F]fluoro-L-tyrosine (FTYR) and O-(2'-[(18)F]fluoroethyl)-L-tyrosine (FET), promising radiopharmaceutical products (RPP) for positron emission tomography (PET), were obtained by asymmetric synthesis. Accumulation of FTYR and FET in the rat tumor "35 rat glioma" and in abscesses induced in Vistar mouse muscles was studied and compared with that of a well-known glycolysis radiotracer 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG). It was shown that the relative accumulation indices of amino acid RPP were considerably lower than those of FDG. At the same time, tumor/muscle ratios were high enough (2.9 for FET and 3.9 for FTYR 120 min after injection) for reliable tumor visualization. The data obtained indicated a possibility in principle to use FTYR and FET for differentiated PET diagnostics of brain tumors and inflammation lesions. Of the tyrosine derivatives studied, FET seems to be the most promising agent due to a simple and easily automated method of preparation based on direct nucleophilic substitution of the leaving tosyloxy group of an enantiomerically pure Ni-(S)-BPB-(S)-Tyr(CH2CH2OTs) precursor by an activated [(18)F]fluoride.

Staphylococcus aureus haem oxygenases are differentially regulated by iron and haem.

Iron acquisition is a vital process for most pathogenic bacteria, as iron is a limiting nutrient during infection. Staphylococcus aureus, an increasingly important pathogen, acquires iron from host haem via elaboration of the iron-regulated surface determinant system (Isd). IsdG and IsdI are haem oxygenases that have been proposed to degrade exogenous haem in the bacterial cytoplasm as a mechanism to liberate free iron for use as a nutrient source. Herein, we report that IsdG and IsdI are both important for S. aureus growth on haemin as a sole iron source and are necessary for full S. aureus pathogenesis. Investigations into the regulation of these enzymes revealed that IsdG and IsdI are differentially regulated by iron and haem through both transcriptional and post-transcriptional mechanisms. Additionally, IsdI was found to be expressed in infected tissues at the sites of abscess formation, suggesting that abscesses are iron-starved microenvironments inside the host. These findings suggest that S. aureus differentially regulates IsdG and IsdI in response to alterations in iron and haem availability during infection.

Cytokine expression in pediatric subperiosteal orbital abscesses.

BACKGROUND: Cytokines have been shown to play a key role in infectious and inflammatory processes. The purpose of the study was to characterize the pattern of cytokine expression in subperiosteal orbital abscesses associated with pediatric orbital cellulitis. METHODS: All pediatric patients over a 5-month period who had orbital cellulitis and a subperiosteal abscess with an adjacent sinusitis requiring surgical drainage of the orbital abscess were given the opportunity to enroll in the study. A protein array membrane and a chemiluminescent detection system were used to identify the presence of 45 cytokines in the subperiosteal abscess fluid. RESULTS: Four abscesses were analyzed with the protein array membrane. Of the 45 cytokines studied for this report, interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist (ra), IL-6, tumor necrosis factor (TNF)-alpha, and TNF-beta were detected in all specimens. Additionally, IL-16, epidermal growth factor related protein, and soluble TNF receptor II were detected in 3 of the 4 specimens. INTERPRETATION: Pediatric orbital cellulitis with subperiosteal abscess is an inflammatory condition with a distinct pattern of cytokine expression. The detection of IL-1, IL-1 ra, IL-6, and TNF suggests that in the future these cytokines may play a role in monitoring disease activity or as potential targets for immunotherapy.

The pathomorphology of Bartholin's gland. Analysis of surgical data.

Medline data did not reveal any statistical approach to Bartholin's gland pathomorphological lesions, especially when the social aspect was considered. Objectives. To complete knowledge and data according to this subject on the basis of own surgical material analysis. Microscopic examinations of histopathological 5 microm thick specimens stained with hematoxylin-eosin and in selected cases with histochemical and immunohistochemical methods on 104 Bartholin's glands taken from 103 female patients in age of 39.4 +/- 9.6. Retention cysts, suppurating lesions (abscesses), extrauterine endometriosis and neoplasms were separated from obtained samples. Localization of lesions, the patients' age and education status were determined. P < 0.05 was considered as statistically significant. Retention cysts were observed in 84.6% of cases, abscesses in 10.6%, extrauterine endometriosis in 2% and neoplasms in nearly 3% of patients. In 54.1% of cases the lesion was localized on the left side, in 45.9% on the right. 17.2% of female patients presented with university education, 29.9% with elementary education, while 52.9% with secondary education. The average age of operated patients amounted to 33 +/- 9.8 years in case of university education, being significantly lower as compared to the average age of secondary (40.5 +/- 7 years) and elementary (42.4 +/- 12 years) education (p < 0.01 and p < 0.02 respectively). 47.7% of retention cysts demonstrated various degrees of inflammatory infiltration. However, the anatomical variability of the ductal and glandular epithelium was higher in cases of non-inflammatory cysts. Considering three Bartholin's gland neoplasms, two were diagnosed as adenocarcinomas and one as a fibromyoma. All of them were observed in female patients with a rare blood type (twice Rh-minus and once AB Rh-plus). There was no significant relationship between the type of pathomorfological lesions and age of operated patients, in spite of the fact that the lowest mean age was observed in woman with endometriosis while the highest in those with neoplasms. The pathology of Bartholin's gland mostly concerns female patients with secondary education. However, early diagnosis is associated with patients with university education. Thus, further investigations considering the statistical analysis of Bartholin's gland neoplasms in order to determine the possible relationship between blood type antigens and neoplasm development are required.

Splenectomy in plasma cell dyscrasias: a review of the clinical practice.

Plasma cell dyscrasias are a group of clinically and biochemically diverse disorders of unknown etiology, characterized by the disproportionate proliferation of one or more clones of B cells, and the presence of a structurally and electrophoretically homogeneous (monoclonal) immunoglobulin or polypeptide subunit in serum or urine. The role of splenectomy in the management of plasma cell dyscrasias has not been well defined. Using MEDLINE, the authors searched the English-language published literature from the year 1970 through September 2005 to determine the indications for splenectomy in plasma cell dyscrasias. A review of the literature in humans and animals supported the idea that the spleen provides a special microenvironment favorable for homing or differentiation of IgM producing B cells, and splenectomy can, at times, lead to remission in Waldenström's macroglobulinemia. The other reported reasons for splenectomy in plasma cell dyscrasias are hypersplenism-related pancytopenia, control of splenic plasmacytomas, and management of a splenic abscess. Splenic infiltration in primary amyloidosis can be an indication for splenectomy, where removal of a large spleen can also reverse an acquired factor X deficiency. Thus, the spleen can be considered a potential target organ for management of plasma cell dyscrasias, and therapeutic success has been achieved with removal of this organ. However, splenectomy can be a potentially morbid procedure in patients with plasma cell dyscrasias, and major postoperative complications include infection, hemorrhage, and thrombosis.

Infectivity of hepatic strain Klebsiella pneumoniae in diabetic mice.

Besides urinary tract infection (UTI) and pneumonia, increased severe liver abscesses caused by Klebsiella pneumoniae (KP), especially in diabetic patients, have been observed in infections acquired in hospitals. This indicates that different KP strains with higher virulence have emerged in recent years. Our goal was to investigate the infectivity of KP isolates in mice from liver abscess or UTI patients. Mice were injected with streptozotocin to induce diabetes. Male ICR mice were infected with KpU1 (UTI strain CG3 for survival experiment only) and KpL1 (liver abscess strain CG5) by tail-vein injection of 5 x 10(4) colony-forming units (CFU) bacterial suspension. The mice survival rates, cytokine level by enzyme-linked immunosorbent assay (ELISA), and bacterial presence in liver tissue by Giemsa stain were examined. The survival rates for the KpL1-infected animals were 28% and 0% in normal and diabetic groups, respectively, whereas, for the KpU1-infected mice, the rates were 100% and 75% during a 30-day observation. Nonsurviving KpL1-infected mice showed > 10(5) bacteria/ml blood and the bacteria appeared in the liver sinus area and inside liver cells. The KpL1-infected mice showed a tendency to increase the blood interleukin 1beta (IL-1beta) level in both nondiabetic and diabetic groups, whereas the tumor necrosis factor-alpha (TNF-alpha) level was significantly decreased in the KpL1-infected diabetic mice (P = 0.002). In conclusion, the KP strain from liver abscess showed a greater virulence in mice than the KP from UTI and was more virulent in diabetic than in nondiabetic mice. The infection with KP from liver abscess significantly decreased the blood TNF-alpha level in diabetes mellitus (DM) mice and the blood IL-1beta level tended to increase in both infected nondiabetic and diabetic groups. High blood bacterial count and appearance of bacteria in liver sinus and cells usually contribute to death of the animals.

Induction of type 3 deiodinase activity in inflammatory cells of mice with chronic local inflammation.

During illness, changes in thyroid hormone metabolism occur, so-called nonthyroidal illness (NTI). NTI has been characterized by a fall of serum T(3) due to decreased extrathyroidal conversion of T(4) into T(3) by liver type 1 deiodinase (D1), without an increase in serum TSH. Type 3 deiodinase (D3) was thought not to play an important role during NTI, but recently it has been shown that D3 activity is up-regulated in liver and skeletal muscle of critically ill patients related to hypoxia. We studied D3 gene expression and activity in liver and muscle/subcutis of mice during illness, which was induced by two different stimuli: bacterial endotoxin (lipopolysaccharide) administration, resulting in an acute systemic response, and a turpentine injection in each hindlimb, resulting in a local sc abscess. Lipopolysaccharide induced a rapid decrease in liver D1 and D3 activity but not skeletal muscle of hindlimb. In contrast, local inflammation induced by turpentine did not decrease liver D1 and D3 activity but increased markedly D3 activity in the muscle/subcutis sample containing the abscess, associated with strongly increased IL-1beta and IL-6 mRNA expression. Inflammatory cells, surrounding the abscess showed D3 and T(3)-transporter monocarboxylate transporter-8 immunoreactivity, whereas muscle cells did not show any immunoreactivity. In conclusion, local inflammation strongly induces D3 activity in inflammatory cells, especially in invading polymorphonuclear granulocytes, suggesting enhanced local degradation of T(3).

Synthesis of leukotriene B4 antagonists labeled with In-111 or Tc-99m to image infectious and inflammatory foci.

In previous studies we demonstrated that lipophilic (99m)Tc-labeled LTB4 antagonist 1 (RP517) accumulated in infectious foci in rabbits, but hepatobiliary clearance hampered imaging of abdominal lesions. We now report the use of cysteic acid as a pharmacokinetic modifier to improve the water solubility and renal clearance of three hydrophilic analogues of 1. Divalent LTB4 antagonist 17 (DPC11870-11) is a DTPA conjugate for radiolabeling with In-111. Monovalent LTB4 antagonists 15 (BMS57868-88) and divalent LTB4 antagonist 18 (BMS57868-81) are conjugated to bifunctional chelator HYNIC for radiolabeling with (99m)Tc. The three compounds labeled efficiently with 111In or (99m)Tc with high radiochemical purity and specific activities. Scintigraphic images obtained in New Zealand White rabbits having acute intramuscular E. coli infection demonstrated that all agents were able to clearly visualize the abscess, and clearance was exclusively renal. The biodistribution of the (99m)Tc-labeled LTB4 antagonists was affected by the coligands used with the HYNIC chelator and by the monovalent or divalent nature of the receptor binding moiety. The best scintigraphic images were obtained with monovalent HYNIC conjugate 15 using tricine and isonicotinic acid as coligands with HYNIC for coordination with (99m)Tc.

Staphylococcus aureus golden pigment impairs neutrophil killing and promotes virulence through its antioxidant activity.

Golden color imparted by carotenoid pigments is the eponymous feature of the human pathogen Staphylococcus aureus. Here we demonstrate a role of this hallmark phenotype in virulence. Compared with the wild-type (WT) bacterium, a S. aureus mutant with disrupted carotenoid biosynthesis is more susceptible to oxidant killing, has impaired neutrophil survival, and is less pathogenic in a mouse subcutaneous abscess model. The survival advantage of WT S. aureus over the carotenoid-deficient mutant is lost upon inhibition of neutrophil oxidative burst or in human or murine nicotinamide adenine dinucleotide phosphate oxidase-deficient hosts. Conversely, heterologous expression of the S. aureus carotenoid in the nonpigmented Streptococcus pyogenes confers enhanced oxidant and neutrophil resistance and increased animal virulence. Blocking S. aureus carotenogenesis increases oxidant sensitivity and decreases whole-blood survival, suggesting a novel target for antibiotic therapy.