Clostridium perfringens infections initially attributed to norovirus, North Carolina, 2010.

We investigated an outbreak initially attributed to norovirus; however, Clostridium perfringens toxicoinfection was subsequently confirmed. C. perfringens is an underrecognized but frequently observed cause of food-borne disease outbreaks. This investigation illustrates the importance of considering epidemiologic and laboratory data together when evaluating potential etiologic agents that might require unique control measures.

Standardized methods and quality control limits for agar and broth microdilution susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum.

An international multilaboratory collaborative study was conducted to develop standard media and consensus methods for the performance and quality control of antimicrobial susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum using broth microdilution and agar dilution techniques. A reference strain from the American Type Culture Collection was designated for each species, which was to be used for quality control purposes. Repeat testing of replicate samples of each reference strain by participating laboratories utilizing both methods and different lots of media enabled a 3- to 4-dilution MIC range to be established for drugs in several different classes, including tetracyclines, macrolides, ketolides, lincosamides, and fluoroquinolones. This represents the first multilaboratory collaboration to standardize susceptibility testing methods and to designate quality control parameters to ensure accurate and reliable assay results for mycoplasmas and ureaplasmas that infect humans.

Trends in nephropathy among HIV-infected patients.

BACKGROUND: Nephropathy complicates the course and adversely impacts on the prognosis of HIV-infected patients. We examined trends and correlates of all-cause nephropathy (ACN). METHODS: Correlates of and trends in ACN were examined in the entire Adult/Adolescent Spectrum of HIV Disease longitudinal observational cohort. Patients were enrolled and followed in the cohort for a median period of 3 years between January 1990 and December 2003 in 11 US metropolitan areas. RESULTS: The incidence of ACN rose among HIV-infected individuals through the mid-1990s, then declined. The proportion of patients with ACN at the time of death increased over the study period. Black race, injection-drug use (IDU), indinavir, hypertension, diabetes, decreased CD4+ lymphocyte count, increased viral load, and increased age were all highly associated with ACN. DISCUSSION: Nephropathy represents an important health disparity impacting HIV-infected blacks and IDU with implications for mortality.

Development and evaluation of a novel multiplex PCR technology for molecular differential detection of bacterial respiratory disease pathogens.

The ResPlex I assay (Qiagen) was designed to amplify and detect DNA of six bacterial respiratory pathogens. This assay was compared with real-time PCR assays based upon the same target sequences for the ability detect the target bacteria by use of both stock strains and specimens from respiratory disease patients. The ResPlex I assay is somewhat less sensitive than real-time PCR assays but offers the advantage of multiple assays in a single reaction.

Cytokines in Mycoplasma pneumoniae infections.

Mycoplasma pneumoniae (M. pneumoniae) is one of the smallest free-living bacteria known. Along with other unique characteristics of this genus, it lacks the typical peptidoglycan cell wall of most eubacteria. Best known for causing tracheobronchitis and atypical pneumonia in humans, this pathogen also causes a number of extrapulmonary syndromes such as meningitis/encephalitis and arthritis. Recent studies also suggest that infection may be associated with chronic conditions such as asthma. Although the mechanisms of M. pneumoniae pathogenesis remain to be elucidated, one important component of M. pneumoniae infections is the induction of proinflammatory and other cytokines in both acute and chronic conditions. In this review, we survey the induction of cytokines by M. pneumoniae in different model systems, and we discuss the possible role of induced cytokines in M. pneumoniae pathogenesis.

Identification of risk factors for infection in an outbreak of Mycoplasma pneumoniae respiratory tract disease.

BACKGROUND: Mycoplasma pneumoniae is one of the most common pathogens that causes community-acquired respiratory tract infection. Outbreaks are well known, and all age groups are susceptible. An outbreak in an army training unit afforded an opportunity to identify possible risk factors for morbidity. METHODS: An outbreak of respiratory illness that occurred in a unit comprising 91 trainees was investigated and analyzed as a cohort study. M. pneumoniae infection was suspected on clinical grounds and was confirmed by polymerase chain reaction, culture, and serologic testing. Data regarding medical history, symptoms, signs, and laboratory tests were collected. RESULTS: During a period of 12 days, 41 soldiers (45.1%) had respiratory illnesses, of which 10 (11.0%) were pneumonia. Comparison of symptomatic and asymptomatic individuals revealed that smoking was associated with higher rates of disease (risk ratio, 2.1; 95% confidence interval [CI], 1.3-3.2; P<.005) and seroconversion (risk ratio, 2; 95% CI, 1.2-3.4; P=.03). In multivariate analysis, both lower acute immunoglobulin G values (adjusted odds ratio, 7.8; 95% CI, 1.4-42.5; P=.018) and smoking (adjusted odds ratio, 5.6; 95% CI, 1.5-20.4; P=.01) were associated with symptomatic infection; stratification according to smoking status revealed that immunoglobulin G levels among nonsmokers were protective. Patients who had pneumonia had lower lymphocyte counts (1400+/-258 vs. 2000+/-465 cells/microL; P=.001). CONCLUSIONS: Smoking and lower preexisting immunoglobulin G levels were strongly associated with M. pneumoniae respiratory infection. These findings emphasize the importance of immunity and cessation of smoking for the prevention of disease. The high attack rate emphasizes the extent of infection transmission among healthy persons living in close contact.

Chlamydia pneumoniae and Mycoplasma pneumoniae in young children from China with community-acquired pneumonia.

Eighty-five cases community-acquired pneumonia (CAP) in children 5 years or younger, confirmed by chest X-ray, and 185 age-matched control patients with diarrhea or dermatitis from the Outpatient Department at Beijing Children's Hospital were enrolled into this study. Nasopharyngeal swab specimens were obtained from all subjects. Real-time PCR-based fluorescence assays were performed for Chlamydia pneumoniae and Mycoplasma pneumoniae. A nested PCR was also run for C. pneumoniae for comparison of assays. C. pneumoniae was found in 3 (3.5%) of CAP cases and in 4 (2.1%) of controls (P = 0.51). M. pneumoniae was found in 6 (7.1%) of CAP cases and in none of the controls (P = 0.001). The agreement rate of the 2 applied PCR methods used for C. pneumoniae detection was 98.5%. Our study demonstrates that M. pneumoniae may play a significant role in CAP affecting children up to 5 years in China, whereas C. pneumoniae in nasopharyngeal specimens was not associated with CAP in this age group.

Laboratory-confirmed cholera and rotavirus among patients with acute diarrhea in four hospitals in Haiti, 2012-2013.

An outbreak of cholera began in Haiti in October of 2010. To understand the progression of epidemic cholera in Haiti, in April of 2012, we initiated laboratory-enhanced surveillance for diarrheal disease in four Haitian hospitals in three departments. At each site, we sampled up to 10 hospitalized patients each week with acute watery diarrhea. We tested 1,616 specimens collected from April 2, 2012 to March 28, 2013; 1,030 (63.7%) specimens yielded Vibrio cholerae, 13 (0.8%) specimens yielded Shigella, 6 (0.4%) specimens yielded Salmonella, and 63 (3.9%) specimens tested positive for rotavirus. Additionally, 13.5% of children < 5 years old tested positive for rotavirus. Of 1,030 V. cholerae isolates, 1,020 (99.0%) isolates were serotype Ogawa, 9 (0.9%) isolates were serotype Inaba, and 1 isolate was non-toxigenic V. cholerae O139. During 1 year of surveillance, toxigenic cholera continued to be the main cause of acute diarrhea in hospitalized patients, and rotavirus was an important cause of diarrhea-related hospitalizations in children.

Seroepidemiologic survey of epidemic cholera in Haiti to assess spectrum of illness and risk factors for severe disease.

To assess the spectrum of illness from toxigenic Vibrio cholerae O1 and risk factors for severe cholera in Haiti, we conducted a cross-sectional survey in a rural commune with more than 21,000 residents. During March 22-April 6, 2011, we interviewed 2,622 residents ≥ 2 years of age and tested serum specimens from 2,527 (96%) participants for vibriocidal and antibodies against cholera toxin; 18% of participants reported a cholera diagnosis, 39% had vibriocidal titers ≥ 320, and 64% had vibriocidal titers ≥ 80, suggesting widespread infection. Among seropositive participants (vibriocidal titers ≥ 320), 74.5% reported no diarrhea and 9.0% had severe cholera (reported receiving intravenous fluids and overnight hospitalization). This high burden of severe cholera is likely explained by the lack of pre-existing immunity in this population, although the virulence of the atypical El Tor strain causing the epidemic and other factors might also play a role.

Pediatric encephalitis: what is the role of Mycoplasma pneumoniae?

BACKGROUND: Encephalitis is a complex, debilitating, and sometimes fatal neurologic condition to which children are especially prone. Mycoplasma pneumoniae, a common respiratory pathogen, has been implicated as an etiology of encephalitis. Evidence for recent or acute M. pneumoniae infection has been demonstrated in limited studies of both pediatric and adult patients with encephalitis. PATIENTS AND METHODS: Unexplained encephalitis cases are referred to the California Encephalitis Project for diagnostic testing. Serum, cerebrospinal fluid, and respiratory specimens are tested by polymerase chain reaction and serology methods for the presence of multiple pathogens, including M. pneumoniae. M. pneumonia-associated cases of encephalitis were compared with other bacterial agents, herpes simplex virus 1, and enterovirus. RESULTS: Of 1988 patients referred to the California Encephalitis Project, evidence of acute M. pneumoniae infection was found in 111 patients, of which 84 (76%) were pediatric patients. Eighty percent of the 84 patients were positive for M. pneumoniae by serology alone. Cerebrospinal fluid polymerase chain reaction for M. pneumoniae was rarely positive (2%). Patients with M. pneumoniae-associated pediatric encephalitis were a median of 11 years old, progressed rapidly (median: 2 days from onset to hospitalization), and were often in the ICU (55%). Symptoms included fever (70%), lethargy (68%), and altered consciousness (58%). Gastrointestinal (45%) and respiratory (44%) symptoms were less common. Compared with patients with other bacterial as well as viral agents, patients with M. pneumoniae-associated encephalitis had fewer seizures and less-severe hospital courses. CONCLUSIONS: M. pneumoniae is the most common agent implicated in the California Encephalitis Project. Patients with M. pneumoniae-associated encephalitis are predominantly pediatric, and their presentations are clinically similar to enterovirus encephalitis, although they frequently require intensive care with prolonged hospitalizations. Given that M. pneumoniae infection is found more than any other pathogen, increased emphasis should be placed on elucidating the role and mechanism of M. pneumoniae in encephalitis.

Mycoplasma pneumoniae subtype-independent induction of proinflammatory cytokines in THP-1 cells.

Mycoplasma pneumoniae can be divided into two main subtypes depending on the amino acid sequences of the P1 adhesin and the P65 protein, both located in the attachment organelle. Differences between these subtypes in infectivity, virulence and interaction with host cells have not been extensively studied. Using ELISA to measure released protein and real-time PCR to quantify mRNA, we have demonstrated that both M. pneumoniae subtypes significantly increased tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8) at comparable levels in THP-1 cells over a 72 h period of time. However, subtype 2 induced a statistically significant increase (P<0.001) in the release of interleukin-1beta at 24 h post-infection compared to subtype 1. These data provide evidence that the induction of proinflammatory cytokine gene and protein expression by M. pneumoniae is not dependent on the infecting subtype.

Mycoplasma pneumoniae and its role as a human pathogen.

Mycoplasma pneumoniae is a unique bacterium that does not always receive the attention it merits considering the number of illnesses it causes and the degree of morbidity associated with it in both children and adults. Serious infections requiring hospitalization, while rare, occur in both adults and children and may involve multiple organ systems. The severity of disease appears to be related to the degree to which the host immune response reacts to the infection. Extrapulmonary complications involving all of the major organ systems can occur in association with M. pneumoniae infection as a result of direct invasion and/or autoimmune response. The extrapulmonary manifestations are sometimes of greater severity and clinical importance than the primary respiratory infection. Evidence for this organism's contributory role in chronic lung conditions such as asthma is accumulating. Effective management of M. pneumoniae infections can usually be achieved with macrolides, tetracyclines, or fluoroquinolones. As more is learned about the pathogenesis and immune response elicited by M. pneumoniae, improvement in methods for diagnosis and prevention of disease due to this organism may occur.

Analysis of eight commercial enzyme immunoassay tests for detection of antibodies to Mycoplasma pneumoniae in human serum.

Mycoplasma pneumoniae is an important etiologic agent of primary atypical pneumonia in children and adults. The diagnosis of M. pneumoniae infection is commonly confirmed through serologic testing. In this study, we used paired sera from 51 patients (all with confirmed M. pneumoniae infection and positive complement fixation [CF] titers) to compare the results of eight enzyme immunoassays (EIAs) available commercially in the United States. We compared two single-use EIAs and six plate-type EIAs. Results from acute-phase sera ranged from only 7 (14%) positive by ImmunoWELL (GenBio) immunoglobulin M (IgM) EIA to 23 (45%) positive by Zeus IgG EIA. When both the acute-phase and convalescent-phase serum samples were examined, positive results ranged from 20 (39%) by the ImmunoWELL (GenBio) IgM assay to 45 (88%) positive by the Remel IgG-IgM EIA. In this study, the single-use EIAs by Remel and Meridian were more reliable than were the plate-type EIAs. Among the plate-type EIAs, the Zeus and DiaSorin assays (which detect antibodies to protein antigens) were more sensitive than the ImmunoWELL assay (which detects antibodies to glycolipid antigens). In general, IgG EIAs on convalescent-phase sera were more concordant with one another than were IgM EIAs with one another. Scatter plot analysis of convalescent-phase sera showed that, as the CF titer dropped, the IgM assays identified fewer positive convalescent-phase sera. In contrast, the IgG assays provided fairly consistent positive results for convalescent-phase sera with CF titers of 64 and above. Results of individual tests and overall limitations of serodiagnostics for M. pneumoniae infections are discussed.

Interleukin-1beta responses to Mycoplasma pneumoniae infection are cell-type specific.

Interleukin-1beta (IL-1beta) is a major proinflammatory cytokine that is involved in many important cellular functions such as proliferation, differentiation, and activation of different cell types. Its mature form is released from the cells in response to various bacterial and viral infections, and it plays a significant role in host defense. Mycoplasma pneumoniae is a small bacterium without a cell wall that causes tracheobronchitis and atypical pneumonia in humans following attachment to respiratory epithelium, as well as extrapulmonary infections. Very little is known about the role of cytokines in pathogenesis or the response of target cells to M.pneumoniae attachment. The purpose of this study was to investigate the ability of M. pneumoniae to induce IL-1beta in human lung epithelial carcinoma A549 and in human monocytic U937 cell lines. Following M. pneumoniae infection, both IL-1beta mRNA and protein were induced in A549 cells vs. no induction in uninfected cells; however, the protein remained inside the A549 cells. Similarly, M. pneumoniae infection strongly increased mRNA and extracellular protein levels in U937 cells, which unlike A549 cells did exhibit baseline constitutive levels. De novo IL-1beta protein expression was verified by cycloheximide studies. M. pneumoniae infection did not affect constitutive caspase-1 mRNA or protein levels in either cell line. Reduced caspase-1 activity in A549 cell lysates suggests the presence of an endogenous caspase-1 inhibitory component in the A549 cells. These collective data confirm previous studies that show that M. pneumoniae is a potent inducer of cytokines following adherence to host target cells, and establish that IL-1beta release in response to M. pneumoniae infection is cell-type specific, thus emphasizing the importance of carefully considering multiple cell types in M. pneumoniae pathogenesis studies involving both immune cells and cytokine release patterns.

Induction of proinflammatory cytokines in human lung epithelial cells during Chlamydia pneumoniae infection.

Chlamydia pneumoniae is an obligate intracellular human pathogen that causes acute respiratory diseases such as pneumonia and bronchitis. Previous studies have established that C. pneumoniae can induce cytokines in mouse and/or human cells, but little information is available on the cytokine response of respiratory epithelial cells, a first line of infection. In this study, heparin treatment of C. pneumoniae significantly reduced its ability to induce interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) mRNA in human lung carcinoma cells, indicating that cytadherence is an important early stimulus for induction of proinflammatory mediators. Although the IL-8, gamma interferon, and TNF-alpha message was consistently induced by infection of A549 cells not treated with heparin, only an elevation of IL-8 protein was detected in A549 supernatants. A549 IL-beta and IL-6 mRNA and supernatant protein profiles were not significantly changed by infection. Heat or UV inactivation of C. pneumoniae only partially reduced the cytokine response, and inhibition of C. pneumoniae protein or DNA synthesis did not affect its ability to induce cytokine gene expression. To prevent stress-induced cytokine release by the A549 cells, centrifugation was not utilized for infection experiments. These experiments establish the importance of cytadherence in cytokine release by cells of respiratory epithelial origin and suggest that further work in the area of cytokine mediators is warranted to gain valuable pathogenic and therapeutic insights.

Regulation of proinflammatory cytokines in human lung epithelial cells infected with Mycoplasma pneumoniae.

Mycoplasma pneumoniae is a small bacterium without a cell wall that causes tracheobronchitis and atypical pneumonia in humans. It has also been associated with chronic conditions, such as arthritis, and extrapulmonary complications, such as encephalitis. Although the interaction of mycoplasmas with respiratory epithelial cells is a critical early phase of pathogenesis, little is known about the cascade of events initiated by infection of respiratory epithelial cells by mycoplasmas. Previous studies have shown that M. pneumoniae can induce proinflammatory cytokines in several different study systems including cultured murine and human monocytes. In this study, we demonstrate that M. pneumoniae infection also induces proinflammatory cytokine expression in A549 human lung carcinoma cells. Infection of A549 cells resulted in increased levels of interleukin-8 (IL-8) and tumor necrosis factor alpha mRNA, and both proteins were secreted into culture medium. IL-1 beta mRNA also increased after infection and IL-1 beta protein was synthesized, but it remained intracellular. In contrast, levels of IL-6 and gamma interferon mRNA and protein remained unchanged or undetectable. Using protease digestion and antibody blocking methods, we found that M. pneumoniae cytoadherence is important for the induction of cytokines. On the other hand, while M. pneumoniae protein synthesis and DNA synthesis do not appear to be prerequisites for the induction of cytokine gene expression, A549 cellular de novo protein synthesis is responsible for the increased cytokine protein levels. These results suggest a novel role for lung epithelial cells in the pathogenesis of M. pneumoniae infection and provide a better understanding of M. pneumoniae pathology at the cellular level.

Development and evaluation of real-time PCR-based fluorescence assays for detection of Chlamydia pneumoniae.

Chlamydia pneumoniae is an important respiratory pathogen recently associated with atherosclerosis and several other chronic diseases. Detection of C. pneumoniae is inconsistent, and standardized PCR assays are needed. Two real-time PCR assays specific for C. pneumoniae were developed by using the fluorescent dye-labeled TaqMan probe-based system. Oligonucleotide primers and probes were designed to target two variable domains of the ompA gene, VD2 and VD4. The limit of detection for each of the two PCR assays was 0.001 inclusion-forming unit. Thirty-nine C. pneumoniae isolates obtained from widely distributed geographical areas were amplified by the VD2 and VD4 assays, producing the expected 108- and 125-bp amplification products, respectively. None of the C. trachomatis serovars, C. psittaci strains, other organisms, or human DNAs tested were amplified. The amplification results of the newly developed assays were compared to the results of culturing and two nested PCR assays, targeting the 16S rRNA and ompA genes. The assays were compared by testing C. pneumoniae purified elementary bodies, animal tissues, 228 peripheral blood mononuclear cell (PBMC) specimens, and 179 oropharyngeal (OP) swab specimens obtained from ischemic stroke patients or matched controls. The real-time VD4 assay and one nested PCR each detected C. pneumoniae in a single, but different, PBMC specimen. Eleven of 179 OP specimens (6.1%) showed evidence of the presence of C. pneumoniae in one or more tests. The real-time VD4 assay detected the most positive results of the five assays. We believe that this real-time PCR assay offers advantages over nested PCR assays and may improve the detection of C. pneumoniae in clinical specimens.

Sequelae of severe respiratory syncytial virus infection in infancy and early childhood among Alaska Native children.

OBJECTIVE: In 1993-1996, we conducted a nested case-control study to determine risk factors for hospitalization with respiratory syncytial virus (RSV) infection among Alaska Native infants and young children. In the current study, we returned to former RSV case-patients and their control subjects during 1999-2001 to determine whether children who are hospitalized with RSV at <2 years of age are more likely to develop chronic respiratory conditions. METHODS: For each former RSV case-patient and control subject from remote villages in southwest Alaska, we reviewed medical records, interviewed parents, performed physical examinations and spirometry, collected sera, and analyzed chest radiographs. Case-patients were identified through surveillance for RSV hospitalization, and matched control subjects without lower respiratory infection (LRI)-related hospitalization were identified. RESULTS: Hospitalization for RSV infection was associated with a significant increase in wheezing, LRIs, and asthma diagnosis during the first 4 years of life. The association decreased with age and was no longer significant by 5 years of age. However, hospitalization for RSV infection was associated with increased respiratory symptoms and increased chronic productive cough at 5 to 8 years of age. Children who were hospitalized with RSV were not more likely at follow-up to have allergies, eczema, or a positive family history of asthma. CONCLUSIONS: Severe RSV infection in infancy may produce airway injury, which is manifested in chronic productive cough with or without wheezing and recurrent LRIs. Although the association of RSV infection with wheezing seems to be transient, children remain at higher risk for chronic productive cough at 5 to 8 years of age. RSV prevention modalities may prevent sequelae that occur early and later in childhood.

SARS surveillance during emergency public health response, United States, March-July 2003.

In response to the emergence of severe acute respiratory syndrome (SARS), the United States established national surveillance using a sensitive case definition incorporating clinical, epidemiologic, and laboratory criteria. Of 1,460 unexplained respiratory illnesses reported by state and local health departments to the Centers for Disease Control and Prevention from March 17 to July 30, 2003, a total of 398 (27%) met clinical and epidemiologic SARS case criteria. Of these, 72 (18%) were probable cases with radiographic evidence of pneumonia. Eight (2%) were laboratory-confirmed SARS-coronavirus (SARS-CoV) infections, 206 (52%) were SARS-CoV negative, and 184 (46%) had undetermined SARS-CoV status because of missing convalescent-phase serum specimens. Thirty-one percent (124/398) of case-patients were hospitalized; none died. Travel was the most common epidemiologic link (329/398, 83%), and mainland China was the affected area most commonly visited. One case of possible household transmission was reported, and no laboratory-confirmed infections occurred among healthcare workers. Successes and limitations of this emergency surveillance can guide preparations for future outbreaks of SARS or respiratory diseases of unknown etiology.