Common Portal Of Entry Research Articles

Clinical and Microbiological Characteristics of Bacteremia Caused by Carbapenemase-producing Enterobacterales in Minami Ibaraki Area, Japan.

Although recent propagation of carbapenemase-producing Enterobacterales (CPE) has become a problem worldwide, the picture of CPE infection in Japan has not fully been elucidated. In this study, we examined clinical and microbiological characteristics of invasive CPE infection occurring at 8 hospitals in Minami Ibaraki Area between July 2001 to June 2017. Of 7294 Enterobacterales strains isolated from independent cases of bacteremia and/or meningitis, 10 (0.14%) were CPE (8 Enterobacter cloacae-complex, 1 Escherichia coli, and 1 Edwardsiella tarda）, all of which had the blaIMP-1 gene and susceptible to gentamicin and trimethoprim/sulfamethoxazole. These strains were isolated from 7 adult and 2 infant bacteremia (1 infant patient developed CPE bacteremia twice) after 2007. The most common portal of entry was intravenous catheters. All of the adult patients were recovered, while the infant patients eventually died. Genomic analyses showed that the 8 E. cloacae-complex strains were classified into 5 groups, each of which was exclusively detected in specific facilities at intervals of up to 3 years, suggesting persistent colonization in the facilities. This study showed that invasive CPE infection in the area was rare, caused by IMP-1-type CPE having susceptibility to various antibiotics, and nonfatal among adult patients.

Experience with Tetanus in a Tertiary Care Hospital in Sudan: A Retrospective Review.

Introduction Tetanus is still a major health issue, especially in rural areas, and is associated with high morbidity and mortality rate. This study was conducted to describe the pattern of presentation and treatment outcome among adult patients infected with tetanus in our environment. Materials and Methods This is a descriptive retrospective hospital-based study conducted in Wad Medani teaching hospital, central Sudan. A total of thirty-one patients were enrolled in this study in the period between January 2018 and December 2020. Results Thirty-one patients were infected with tetanus during the study period. They were 23 (74.2%) males and 8 (25.8%) females with a male-to-female ratio of 2.875 : 1. Their ages ranged from 20 to 70 years, and most of them (48.4%) were free workers. Acute injuries were the most common portal of entry (64.51%), and commonly involved the lower limbs (48.38%). Lock jaw (54.8%), muscle spasm (51.6%), and neck pain and stiffness (45.2%) were the most common presentation. Supportive measures along with surgical toilet and debridement, human tetanus immunoglobulin, antibiotics, and muscle relaxants were initiated in all patients. The most common antibiotics used were Penicillin V and Ceftriaxone. A muscle relaxant was administered to aid in relieving the spasms. Complication rate was 61.29% and included pulmonary and cardiovascular complications. Fifteen patients died accounting for an overall mortality rate of 48.4%. Conclusions Tetanus remains a disease with high morbidity and mortality. The unknown/incomplete vaccination status among study participants, inadequate management, and lack of equipped resources lead to a devastating outcome as in Sudan.

Clinical Characteristics and Antimicrobial Susceptibility Trends inCitrobacterBacteremia: An 11-Year Single-Center Experience

BackgroundRecently, Citrobacter freundii bacteremia outbreak in a neonatal intensive care unit has attracted public attention in Korea. However, Citrobacter bacteremia is uncommon and usually occurs in patients with underlying diseases such as malignancy and hepatobiliary diseases. Increase in resistance and emerging of multidrug resistance among Citrobacter species have gradually been reported. The aim of this study was to investigate the clinical characteristics and outcome of C. freundii and non-freundii bacteremia and antimicrobial susceptibility trends.Materials and MethodsWe reviewed the medical records of patients with Citrobacter bacteremia at St. Mary's Hospital, from 2007 to 2017.ResultsA total of 43 patients with a median age of 72 (24-93) years was identified and 90.7% of them had comorbidities. Twenty-nine (67.4%) patients had C. freundii bacteremia while 14 had non-freundii bacteremia (six of C. braakii, five of C. koseri, two of C. amalonaticus and one of C. youngae). A total of 26 (51.2%) patients had community-acquired infection and intra-abdominal infection including hepatobiliary tract was the most common portal of entry (24/43, 55.8%). Moreover, hepatobiliary tract was the leading primary site of nosocomial infection (9/17, 52.9%). Polymicrobial bacteremia was observed in 21 (48.8%) patients. The percentages of Citrobacter species susceptible to ampicillin, amikacin, aztreonam, cefazolin, cefoxitin, cefotaxime, cefepime, piperacillin-tazobactam, ciprofloxacin, and imipenem were 9.5%, 97.6%, 73.8%, 9.5%, 14.3%, 71.4%, 92.9%, 83.3%, 83.3% and 100%, respectively. The resistance rate did not increase during the study period. Of 39 patients treated with antibiotics, 36 (92.3%) received appropriate empirical antibiotics. Overall mortality was 18.6%. High Charlson comorbidity index and Pitt bacteremia score were significant risk factors for death in univariate analysis and showed trends in the multivariate analysis. No significant difference in clinical features and antimicrobial susceptibility rate was observed between C. freundii and non-freundii bacteremia.ConclusionCitrobacter bacteremia was predominant in the elderly with comorbidities, while no pediatric case was observed. Hepatobiliary tract is the leading primary focus of bacteremia both in community-acquired and nosocomial infection. The rate of susceptibility to antibiotics has not changed in the last 11 years.

Legal Briefs: Could Herpes Meningocephalitis Have Been Prevented in this Infant?

A 14-day-old female infant born at term was brought to the pediatrician because her right eye was slightly swollen and had a watery discharge. The mother stated that she had an unremarkable pregnancy and vaginal delivery. The records reflected that the infant was healthy at the time of the 48-hour discharge. The physician concluded that a tear duct obstruction was present and asked the parents to massage it. The pediatrician retained by the plaintiff explained that an evaluation of the eye with cultures should have been done. The plaintiff explained that in the past, infants with Neisseria gonorrhoeae conjunctivitis presented at 2 to 5 days of age, but partial suppression by ocular prophylaxis has altered the onset to a later time. Chlamydia trachomatis conjunctivitis typically appears 5 to 14 days after birth. Herpes simplex virus (HSV) conjunctivitis was also an important infection to consider because of potentially devastating consequences if not recognized, especially with the eye being a common portal of entry and site of viral replication. The pediatrician retained by the defense disagreed and stated that it was not standard of care to perform a culture on the discharge, given this infant’s clinical findings . Four days after the pediatrician visit, the mother brought her infant to the emergency department (ED) because of an elevated temperature of 100.5oF (38.1oC). The mother said that an aunt had a cold sore on her mouth when visiting the infant, but no other history of infection was noted at home and the mother again said that her pregnancy was unremarkable. In the ED, the infant’s temperature was 101.5oF (38.6oC). Except for an elevated heart rate of 175 beats/min and periorbital swelling of an erythematous right eye that had a watery discharge, the infant’s examination findings were normal. Two hours after arrival at the …

Identifying the Portal of Entry in Bacterial Endocarditis: A Quest to the Source

Background: Infective endocarditis (IE) results from bacterial seeding of the heart valves. Causative bacteria can be grouped according to the likely source such as skin, oral cavity or bowel. This allows for screening of a portal of entry (POE) to prevent recurrent IE and to identify underlying pathologies such as colonic malignancies or oral lesions. Rates of routine screening for POE are largely unknown. Methods: At our tertiary hospital, a retrospective analysis identified 86 patients over 18 months with a new diagnosis of infective endocarditis. We assessed if a POE was identified and if screening for POE was performed appropriate to the causative bacteria. Results: The POE was identified in 51 (59%) of patients. Intravenous drug use was present in 28% of identified POEs. Cutaneous infection was the most common POE (67%) followed by oral and gastrointestinal sources. Over 50% of infections with gastrointestinal and oral flora arose from an unknown POE. In 5 patients with gastrointestinal POEs identified, 2 had pre-malignant polyps and 1 had a malignant tumour. 48% of patients requiring inpatient valve surgery had an unknown POE with 4 cases of recurrent-prosthetic IE. Conclusions: In the absence of a protocol for identifying the POE in infective endocarditis, the source of infection remains unknown in a significant number of patients. Without identifying the source of the initial insult, these patients are at future risks of re-infection, which carries significant morbidity and mortality, especially in those with prosthetic heart valves. Our results highlight the need to standardise POE investigation to reduce the incidence of recurrent infective endocarditis.

Profile and outcome of patients with post-neonatal tetanus in a tertiary centre in south west Nigeria: any remarkable reduction in the scourge?

IntroductionThe incidence of tetanus has remained unacceptably high in developing countries. We aimed to describe the profile and outcome of children with tetanus admitted at the Lagos State University Teaching Hospital (LASUTH), Ikeja.MethodsA prospective and cross-sectional study of children aged 1 month to 12 years of age admitted with clinical diagnosis of tetanus, between January 2011 and December 2013, at the Paediatric department of LASUTH. The age, sex, presenting complaint, immunization status, portal of entry, socio-economic class, complications, duration of admission and outcome of the subjects were analyzed using Microsoft Excel supplemented with Statistical Package for Social Sciences (SPSS) version 17.0. Level of significance set at p< 0.05.ResultsA total of 49 subject participated in the study. Male: Female ratio was 1.7: 1.0. mean age ± SD of 6.5± 3.2 years. Only 24.5% of the subjects were fully immunized, lower limb injury was the most common portal of entry (34.7%). Majority (79.6) were of the middle and lower social classes. Most of the subjects (67.3%) presented with generalised spasm. Only 1 patient (2.0%) did not have trismus. Case fatality rate was 4.1%.ConclusionTetanus is still prevalent among children in our environment. It is commoner among those with no immunization or incomplete immunization, commoner in those in the middle and lower social class. Lower limb injury was the most common portal of entry. Trismus was a common presenting feature. There is a need to develop programmes with will help improve compliance to immunization.

Infecciones por Corynebacterium spp., Bacillus spp. y Listeria

Corynebacteria are mostly harmless, however, there is more and more evidence of its pathogenicity, especially as a cause of nosocomial infection in immunocompromised patients. Is the most important genus, Corynebacterium diptheriae is the most important species. Humans are the only known reservoir of diphtheria and respiratory tract the main source of transmission. The tonsillar and pharyngeal involvement is the most common clinical form. The clinical efficacy of the vaccine is 97 %. Fermentative not lipophilic corynebacteria (C. striatum, C. amycolatum) and lipophilic (C. jeikeium, C. urealyticum) are mainly related to nosocomial infections. Infections with Bacillus spp. traditionally have been limited to Bacillus anthracis anthrax responsible, a zoonosis caused by the entry of spores through skin abrasions, inhalation or ingestion of the same, which depend on its clinical forms and Bacillus cereus producing both disease as localized gastrointestinal infection. Listeria monocytogenes is an intracellular pathogen with a predilection for patients with impaired cellular immunity (pregnant and immunocompromised). The digestive tract is the most common portal of entry. The definitive diagnosis is made by culture. The clinical picture varies from meningitis, sepsis, perinatal and local infections. The treatment of choice is ampicillin to that associated gentamicin.

Anthrax Lethal Toxin Disrupts Intestinal Barrier Function and Causes Systemic Infections with Enteric Bacteria

A variety of intestinal pathogens have virulence factors that target mitogen activated protein kinase (MAPK) signaling pathways, including Bacillus anthracis. Anthrax lethal toxin (LT) has specific proteolytic activity against the upstream regulators of MAPKs, the MAPK kinases (MKKs). Using a murine model of intoxication, we show that LT causes the dose-dependent disruption of intestinal epithelial integrity, characterized by mucosal erosion, ulceration, and bleeding. This pathology correlates with an LT-dependent blockade of intestinal crypt cell proliferation, accompanied by marked apoptosis in the villus tips. C57BL/6J mice treated with intravenous LT nearly uniformly develop systemic infections with commensal enteric organisms within 72 hours of administration. LT-dependent intestinal pathology depends upon its proteolytic activity and is partially attenuated by co-administration of broad spectrum antibiotics, indicating that it is both a cause and an effect of infection. These findings indicate that targeting of MAPK signaling pathways by anthrax LT compromises the structural integrity of the mucosal layer, serving to undermine the effectiveness of the intestinal barrier. Combined with the well-described immunosuppressive effects of LT, this disruption of the intestinal barrier provides a potential mechanism for host invasion via the enteric route, a common portal of entry during the natural infection cycle of Bacillus anthracis.

Clinical profile and outcome of adult tetanus in Kano

Introduction: Though tetanus is rare in the developed countries of the world, it remains a major public health hazard in the developing world like Nigeria despite availability of inexpensive vaccine. We undertook a 6-year study of all tetanus cases managed at two tertiary centres in Kano.Methodology: Demographic and clinical data of all adult tetanus patients managed at Aminu Kano Teaching Hospital and Murtala Muhammad Specialist Hospital, Kano between January 2004 to December 2009 were collected and analyzed.Results: A total of 146 patients were admitted in the two facilities out of which complete data was obtained from 126 patients. All patients had generalised tetanus. There were 93 (73.8%) males and 33 (26.2%) females. Their age ranges between 17 and 62 years; mean (35.2 ± 1.3) years. Majority of the patients were in the age bracket of 21 – 30 years with most (50.8%) being farmers. The most common portal of entry was leg wound while portal of entry was not identifiable in 37 (29.4%) patients. Incubation period was less than 48 hours in 46 (51.7%) and period of onset was less than 48 hours in 64 (50.8%) patients. Aspiration pneumonitis and laryngospasm were documented complications in 12 (9.5%) and 26 (20.6%) of the patients, respectively. The overall mortality rate was 46%.Conclusion: Tetanus remains an important disease with substantial mortality in Kano. The males and farmers are most frequently affected. The overall mortality rate was 46% with the value being highestamong severe (87.2%) and the very severe (92.3%) cases.

Legal Briefs

A 3,545-g, 35–3/7 weeks', large for gestational age (LGA) male is delivered to an insulin-dependent diabetic mother who became pregnant with the help of a fertility specialist. After conception, a general obstetrician managed her pregnancy. The antenatal course was uneventful except for a history of herpes simplex virus (HSV) infection. A cesarean section was planned at 38 weeks' gestation because of a relatively large fetus and a small pelvic outlet. The mother developed premature rupture of membranes (PROM) at 35 weeks' gestation, and 48 hours later, labor began. The obstetrician was out of town, and the mother was triaged to a midwife for the delivery. The mother's last HSV outbreak was 2 weeks before delivery, with lesions healing 4 days before delivery. The mother claimed in her deposition that she told the midwife about her history of herpes. The medical records from the fertility specialist and the obstetrician documented the history of HSV. The medical records reflecting the herpes were computerized and available to the midwife and the nurses who managed labor and delivery. The infant was delivered by a spontaneous vaginal vertex delivery. The Apgar scores were 8 at 1 minute and 9 at 5 minutes. The infant was asymptomatic and observed for 6 hours before rooming-in with his mother. Multiple bedside glucose evaluations were read as normal. A complete blood count (CBC) yielded unremarkable results. A blood culture was reported as negative on the final reading. Vital signs were stable. The infant was sleepy at the breast, but the mother fed him formula. The discharge examination was performed at 41 hours, and the only notable finding besides the LGA and late preterm gestation was that an ophthalmic examination could not be performed because the eyes were closed. The grandmother stated in her deposition that the baby's eyes were …

Host Factors and Portal of Entry Outweigh Bacterial Determinants To Predict the Severity of Escherichia coli Bacteremia

Escherichia coli ranks among the organisms most frequently isolated from cases of bacteremia. The relative contribution of the host and bacteria to E. coli bacteremia severity remains unknown. We conducted a prospective multicenter cohort study to identify host and bacterial factors associated with E. coli bacteremia severity. The primary endpoint was in-hospital death, up to 28 days after the first positive blood culture. Among 1,051 patients included, 136 (12.9%) died. Overall, 604 (57.5%) patients were female. The median age was 70 years, and 202 (19.2%) episodes were nosocomial. The most frequent comorbidities were immunocompromised status (37.9%), tobacco addiction (21.5%), and diabetes mellitus (20.1%). The most common portal of entry was the urinary tract (56.9%). Most E. coli isolates belonged to phylogenetic group B2 (52.0%). The multivariate analysis retained the following factors as predictive of death: older age (odds ratio [OR] = 1.25 [95% confidence interval {CI}, 1.09 to 1.43] for each 10-year increment), cirrhosis (OR = 4.85 [95% CI, 2.49 to 9.45]), hospitalization before bacteremia (OR = 4.13 [95% CI, 2.49 to 6.82]), being an immunocompromised patient not hospitalized before bacteremia (OR = 3.73 [95% CI, 2.25 to 6.18]), and a cutaneous portal of entry (OR = 6.45 [95% CI, 1.68 to 24.79]); a urinary tract portal of entry and the presence of the ireA virulence gene were negatively correlated with death (OR = 0.46 [95% CI, 0.30 to 0.70] and OR = 0.53 [95% CI, 0.30 to 0.91], respectively). In summary, host factors and the portal of entry outweigh bacterial determinants for predicting E. coli bacteremia severity.

Clinical significance of Staphylococcus saprophyticus identified on blood culture in a tertiary care hospital

Staphylococcus saprophyticus is a well-known cause of acute uncomplicated urinary tract infection in young women. However, the clinical significance of this organism isolated from blood culture has not been determined. We assessed the clinical significance and characteristics of S. saprophyticus identified on blood culture. A total of 24 patients were identified, and 7 patients (29.2%) were considered to have clinically significant bacteremia. Of the 7 patients with clinically significant bacteremia, hematologic malignancy was the most common underlying illness (5 patients), and tunneled-central venous catheter was the most common portal of entry (4 patients). In no case did S. saprophyticus bacteremia originate from the urinary tract. One patient died during hospitalization. However, the death was not directly related to bacteremia. In conclusion, our data suggest that bacteremia caused by S. saprophyticus is most commonly associated with tunneled-central venous catheter in patients with hematologic malignancies and may be associated with a lower risk of mortality.

Síndrome del shock tóxico estreptocócico: experiencia de los últimos 10 años en un hospital terciario

In the last two decades there has been a reported increase in the incidence of streptococcal toxic shock syndrome (STSS). The objective of this study was to determine the clinical and epidemiological characteristics of this infection. Retrospective study of all cases of STSS diagnosed at a single tertiary hospital over the last ten years. We report 13 cases of STSS (8 men, mean age 62 years). The mean annual incidence was 0.19 episodes/100,000 population from 1994 to 1998 and 0.53 episodes/100,000 population from 1999 to 2003 (p = 0.059). All patients had at least one underlying disease and there were no intravenous drug users. The most common portals of entry were the skin and soft tissues (85%) and all but one patient had a positive blood culture. Two cases were nosocomial and five patients required surgery (amputation and/or debridement). There was a high mortality rate (85%) and a rapid course from onset to death; nine patients died within four days after establishing the diagnosis. The incidence of SSTS has increased over the last five years at our hospital. Elderly patients with underlying medical conditions were more susceptible to acquiring this infection. Early mortality was very high.

Choque tóxico por streptococcus beta-hemoliticus do grupo A.

In the last years has been observed an increased incidence of invasive group A beta-hemolytic streptococcal infections, including the toxic shock syndrome. The most common portal of entry is the skin and mucous membranes. The toxic shock syndrome can occurred as a rare complication of pharyngitis. The association between varicella and the use of nonsteroidal antiinflammatory drugs with necrotizing fasciitis by Streptococcus pyogenes has been discussed without reach at consensus, but some authors disapproved the use of nonsteroidal antiinflammatory drugs in this viral infection. The authors reported the clinical case of a 12 year old adolescent, that 15 days after the diagnosis of mononucleosis infectious confirmed by serology and treated with ibuprofen, was internment by streptococcal toxic shock syndrome with rhabdomyolysis, hepatitis, cellulitis of the leg, arthritis of the knee and pleural effusion. Therapeutics was made with penicillin G and clindamycin. We present this case for the severity of the clinical situation and for the questions that rise.

Tetanus: an analysis of the prognosticating factors of cases admitted into the medical wards of a tertiary hospital in a developing African country between 1990 and 2000

This is an analysis of the effects of prognosticating factors on the outcome of patients with tetanus who were seen in our hospital between 1990 and 2000. Tetanus remains a major public health hazard associated with high mortality. A total of 66 cases were analysed with a slight female preponderance. The mortality rate was 26.2% with an age-adjusted fatality rate of 16.2% for those under 40 years of age. This increased to 75% for those patients above 70 years of age. The most common portal of entry was lower limb, specifically the foot, and this was the case in 56%. The socio-economic status of the patients, the immunisation status, the incubation period, the age of the patient, the severity of the spasms, the duration of hospital stay, the type of treatment received and the onset time were found to affect the outcome of the patients. We recommend that health care providers should take every opportunity to review the vaccination status of their parents and provide tetanus vaccine when indicated, and recall when treating injured patients that many middle-aged and older adults are not adequately immunised against tetanus.

Candidemia in French hospitals: incidence rates and characteristics

To determine the incidence of candidemia in French hospitals. A representative sample of 25 French hospitals [nine teaching hospitals (TH), ten general hospitals (GH) and six cancer referral centers (CRC)] was randomly selected. The incidence rates of candidemia per number of admissions and per patient-days of hospitalization were determined and extrapolated to the national level. From January 1, 1995 to December 31, 1995, the overall incidence rate per 1000 admissions was 0.29, ranging from 0.71/1000 in CRC, to 0.17/1000 in GH. The overall incidence for 1000 patient-days was 0.035 and the highest incidence was also observed in CRC (0.116/1000), followed by TH (0.052/1000). Candida albicans (53%) was the most common species isolated, a central venous catheter (26%) was the most common portal of entry and 50% of the candidaemic patients had a neoplasm. This study should enable us to optimize surveillance, prevention and treatment of these potentially life-threatening infections.

Infecciones invasoras por estreptococos del grupo A: características clínicas y análisis microbiológico de 31 casos

In the last two decades an increase in the incidence of invassive Streptococcus pyogenes infections has been reported in several countries. The objective of this study was to determine the clinical features of these infections in our hospital. Retrospective study (1995-1998) of patients admitted at Son Dureta Hospital, Palma de Mallorca, Spain, who had S. pyogenes recovered from blood, sterile fluids or soft tissues. Patients clinical records were reviewed and bacterial isolates characterized. A total of 31 patients with invassive infections caused by S. pyogenes were identified. The annual incidence rates (number of episodes/1,000 admissions) were: 0.13 (1995), 0.20 (1996), 0.27 (1997), and 0.23 (1998). The mean age of patients was 41 years. Seventy four percent of patients had some underlying disease, and the most relevant conditions included: diabetes mellitus (5), parenteral drug abuse (4), chronic alcoholism (3), chronic liver disease (3) and infection with the human immunodeficiency virus (3). The most common portal of entry was the skin (78%). The initial clinical presenting form was cellulitis (39%). Necrotizing fasciitis, septic shock, and streptococcal toxic shock syndrome (STSS) were observed in 9.6%, 12.9%, and 6.4% of patients, respectively. The mortality rate was 16.1%. The phenotypic characterization of S. pyogenes isolates indicated that most isolates were of mucoid type and identified 11 different M serotypes, M1 being the most common. A steady increase in the incidence of invassive infections caused by S. pyogenes was observed since 1995 to 1997 in our hospital. Patients with certain underlying conditions are more susceptible to acquire these infections. The worst outcome of these infections corresponded to elderly patients, those with septic shock or STSS. Most strains responsible for these infections were encapsulated and the M1 serotype predominated.

Viridans-group streptococcal infections in immunocompromised hosts

Viridans streptococci, a diverse group of streptococcal species, are important causes of sepsis and pneumonia in the neutropenic host and sepsis and meningitis in the neonate. The oral mucosa is the most common portal of entry. Among the factors that predispose to development of viridans streptococcal sepsis are: profound neutropenia; mucositis, especially oral mucositis; cytarabine (Ara-C) therapy, which seems to have an effect beyond its association with mucositis; young age; and trimethoprim-sulphamethoxazole or quinolone administration. Fever is usually more than 39°C and prolonged for several days even though blood cultures are typically negative after 24 h of therapy. The majority of patients recover uneventfully if appropriate therapy is initiated early. However, fulminant septic shock may occasional occur at onset. Delayed shock 2 or 3 days after presentation may also occur despite administration of microbiologically effective antibiotics. In severe cases, adult respiratory distress syndrome may be manifested two or three days after the initial bacteremia. There is considerable variability among institutions, but the median death rate associated with viridans streptococcal sepsis is about 10%. Local susceptibility patterns should be used to guide initial therapy for suspected viridans streptococcal infections. Some isolates of viridans streptococci are resistant to penicillins and cephalosporins, in which case vancomycin is preferred. Recurrence during subsequent neutropenic episodes is not unusual.

Cell proliferation in nasal respiratory epithelium of people exposed to urban pollution.

The nasal passages are a common portal of entry and are a prime site for toxicant-induced pathology. Sustained increases in regenerative cell proliferation can be a significant driving force in chemical carcinogenesis. The atmosphere in Mexico City contains a complex mixture of air pollutants and its residents are exposed chronically and sequentially to numerous toxicants and potential carcinogens. We were concerned that exposure to Mexico City's atmosphere might induce cytotoxicity and increase nasal respiratory epithelial cell proliferation. Nasal biopsies were obtained for DNA cell cycle analysis from 195 volunteers. The control population consisted of 16 adults and 27 children that were residents in a Caribbean island with low pollution. The exposed Mexico City population consisted of 109 adults and 43 children. Sixty-one of the adult subjects were newly arrived in Mexico City and were followed for 25 days from their arrival. Control children, control adult and exposed Mexico City children all had similar percentages of cells in the replicative DNA synthesis phase (S phase) of the cell cycle (%S). A significant increase in %S in nasal epithelial cells was seen in exposed adult residents in Mexico City biopsied at three different dates compared with control adults. Newly arrived adults exhibited a control level of cell turnover at day 2 after coming to the city. However, at days 7, 14 and 25 they exhibited significant increases in %S. These data demonstrate an increased and sustained nasal cell turnover rate in the adult population observable in as little as 1 week of residence in Mexico City. This increase in cell proliferation is in agreement with other reports of induced pathological changes in the nasal passages of Mexico City dwellers. These observations suggest an increased potential risk factor of developing nasal neoplasms for residents of large cities with heavy pollution.

Cyclical Peaking of Streptococcal Infections: Recent and Historical Trends

To the Editors-In his recent article on the dynamics of emerging infectious diseases, Krause [1] reprinted a graph showing the incidence and fatality rates for scarlet fever in Oslo from 1863 to 1878 [2]. This graph displays a cyclical peaking of incidence every 34 years. A study of group A streptococcus (GAS) in our institution produced a strikingly similar picture (figure 1). We retrospectively studied the files of 64 patients who had blood cultures positive for GAS at the Shaare Zedek Medical Center in Jerusalem, a 550-bed facility. The majority of patients were adult (69%) and female (63%), concurring with the high female-to-male ratio reported by others [3]. The most common portal of entry was the skin; however, no source was found in 20% of infections. We found no seasonal variation, such as an increased incidence of GAS infections during the winter months, as reported (with controversy) by others [4]. Four patients had concomitant staphylococcal infections, thought to be one cause for lack of response to penicillin in GAS infections [5]. These 4 patients, however, did respond to penicillin. Unlike Krause's emerging toxic shock-like syndrome [1], all of the 8 patients (13%) who died did so as a result of the primary illness, which initially predisposed them to infection, and not because of the GAS infection. The observed peaks in incidence of GAS, which are almost identical to those seen >100 years ago, remain a mystery. The multifactorial etiology of infection and the multifaceted presentation of GAS infection (from sore throat to toxic shock-like syndrome) make the understanding of this phenomenon extremely difficult. Further epidemiologic and clinical studies may help us to better understand the behavior patterns of this organism and