Monitoring polio supplementary immunization activities using an automated short text messaging system in Karachi, Pakistan

PROBLEM

Polio remains endemic in many areas of Pakistan, including large urban centres such as Karachi.

APPROACH

During each of seven supplementary immunization activities against polio in Karachi, mobile phone numbers of the caregivers of a random sample of eligible children were obtained. A computer-based system was developed to send two questions--as short message service (SMS) texts--automatically to each number after the immunization activity: "Did the vaccinator visit your house?" and "Did the enrolled child in your household receive oral polio vaccine?" Persistent non-responders were phoned directly by an investigator.

LOCAL SETTING

A cluster sampling technique was used to select representative samples of the caregivers of young children in Karachi in general and of such caregivers in three of the six "high-risk" districts of the city where polio cases were detected in 2011.

RELEVANT CHANGES

In most of the supplementary immunization activities investigated, vaccine coverages estimated using the SMS system were very similar to those estimated by interviewing by phone those caregivers who never responded to the SMS messages. In the high-risk districts investigated, coverages estimated using the SMS system were also similar to those recorded--using lot quality assurance sampling--by the World Health Organization.

LESSONS LEARNT

For the monitoring of coverage in supplementary immunization activities, automated SMS-based systems appear to be an attractive and relatively inexpensive option. Further research is needed to determine if coverage data collected by SMS-based systems provide estimates that are sufficiently accurate. Such systems may be useful in other large-scale immunization campaigns.

Fluoroquinolones for treating typhoid and paratyphoid fever (enteric fever)

BACKGROUND

Fluoroquinolones are recommended as first-line therapy for typhoid and paratyphoid fever, but how they compare with other cheaper antibiotics and different fluoroquinolones is unclear.

OBJECTIVES

To evaluate fluoroquinolone antibiotics for treating enteric fever in children and adults compared with other antibiotics, different fluoroquinolones, and different treatment durations of the same fluoroquinolone.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (August 2004), CENTRAL (The Cochrane Library Issue 3, 2004), MEDLINE (1966 to August 2004), EMBASE (1974 to August 2004), LILACS (1982 to August 2004), conference proceedings, reference lists, and contacted researchers.

SELECTION CRITERIA

Randomized controlled trials of fluoroquinolones in people with blood or bone marrow culture-confirmed enteric fever.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of trials and extracted data. We calculated the odds ratio (OR) for dichotomous data with 95% confidence intervals. We analysed norfloxacin separately.

MAIN RESULTS

Thirty-three trials met the inclusion criteria; 22 had unclear allocation concealment, and 29 were not blinded. Three trials exclusively included children, and two studied outpatients. The main analysis examined clinical failure, microbiological failure, and relapse. Compared with chloramphenicol, fluoroquinolones were not statistically significantly different for clinical (544 participants) or microbiological failure (378 participants) in adults; they reduced clinically diagnosed relapse in adults (OR 0.14, 0.04 to 0.50; 467 participants, 6 trials), but this was not statistically significant in participants with blood culture-confirmed relapse (121 participants, 2 trials). Compared with co-trimoxazole, we detected no statistically significant difference (82 participants, 2 trials). Among adults, fluoroquinolones reduced clinical failure compared with ceftriaxone (OR 0.08, 0.01 to 0.45; 120 participants, 3 trials), but showed no difference for microbiological failure or relapse. We detected no statistically significant difference between fluoroquinolones and cefixime (80 participants, 1 trial) or azithromycin (152 participants, 2 trials). In trials of hospitalized children, fluoroquinolones were not statistically significantly different from ceftriaxone (60 participants, 1 trial, involving norfloxacin) or cefixime (82 participants, 1 trial). Norfloxacin had more clinical failures than other fluoroquinolones (417 participants, 5 trials). Trials comparing different durations of fluoroquinolone treatment showed no statistically significant differences (693 participants, 8 trials).

AUTHORS' CONCLUSIONS

Many trials were small, and methodological quality varied widely. Although enteric fever most commonly affects children, trials in this group were particularly sparse. Insufficient data in all comparisons preclude any firm conclusions to be made regarding superiority of fluoroquinolones over first-line antibiotics in children and adults.

Effect of whole body hyperthermia on radiation therapy of transplanted fibrosarcoma in Swiss mice

The exposure of normal mice to whole body hyperthermia (1 h WBH at 39 or 40 degrees C), 20 or 48 h prior to total body irradiation (TBI) with lethal doses of gamma-rays affords significant protection as assessed by survival. The radioprotective effect of WBH, as observed in normal mice, diminished in tumour bearing mice depending upon the size of tumour. Treatment of tumour bearing mice with mild WBH, 20 h prior to local irrradiation (LIR), did not protect the transplanted tumour against radiotherapy with a single dose of 20 Gy or fractionated dose (in five fractions) of 7.5 Gy on alternate days. In fact, mild WBH treatment enhanced the tumour regression and increased the mean survival time after fractionated dose therapy. However, the prior mild WBH was found to be ineffective in protecting normal tissue, as assessed by skin contraction after local irradiation (50 Gy). This indicates that mild WBH treatment given 20 h prior to local radiotherapy enhances fibrosarcoma tumour regression but cannot protect skin (normal tissue) against local irradiation. It appears that radioprotection of animals by WBH may be the consequence of its radioprotective effect on haemopoietic tissues mediated through certain cytokines. Perhaps WBH may not have a radioprotective effect on other tissues, as evident from skin contraction studies.

Effect of mild whole body hyperthermia on cytotoxic action of N-methyl-N'-nitro-N-nitrosoguanidine in Swiss mice

Studies were carried out to ascertain the efficacy of mild whole body hyperthermia (WBH) as a modifier of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) cytotoxicity in mice. Adult Swiss male mice, 6-8 weeks old, weighing about 25 g were exposed to mild WBH (39 degrees C, 1 h) in a precision temperature controlled environmental chamber maintained at 50-60% relative humidity. Twenty-four hours after treatment, animals were administered with different doses of MNNG either by intraperitoneal (i.p.) injections or by feeding through drinking water and were monitored for survival. The studies revealed that the exposure of animals to mild WBH, 24 h prior to MNNG administration results in an increase in survival and recovery in mean body weight compared with those administered with MNNG only. This suggests that prior WBH treatment can effectively reduce the MNNG cytotoxicity in mice.

Impact of simple screening criteria on utilization of low-yield bacterial stool cultures in a Children's Hospital

OBJECTIVE

To determine diagnostic yield of stool cultures for Salmonella, Shigella, Campylobacter jejuni, Yersinia enterocolitica, and Escherichia coli O157:H7 (SSCYE) among hospitalized children and to develop guidelines for appropriate use of these tests. Setting. Tertiary care pediatric hospital.

DESIGN

Computerized records from the Microbiology Laboratory from January 1992 to December 1996 were reviewed retrospectively to collect data on the number of stool cultures performed in inpatients and outpatients, the length of hospital stay at the time cultures were sent, and diagnostic yield of cultures in hospitalized patients. A detailed review of medical records of all patients with a stool pathogen isolated after 3 days of hospitalization was also undertaken. The results from this retrospective analysis were used to develop guidelines to reduce unwarranted stool cultures and to educate medical care providers in the appropriate use of these tests. The impact of these guidelines on reduction in the volume of stool cultures performed on hospitalized patients was measured prospectively from January 1998 to June 1998.

RESULTS

A total of 27 110 stool cultures for SSCYE were performed in the 5-year study period. Of the 14 125 cultures from inpatients, 174 (1.2%) were positive. Among the cultures from inpatients, 9378 (66%) were from patients hospitalized for >3 days. Only 13 (.14%) were positive. Of these 13 cultures, 4 represented nosocomial infections, whereas the remaining 9 cultures either were sent to document clearance from a patient known previously to be infected with an enteric pathogen (7), or were attributed to delayed testing in individuals admitted with a diarrheal illness (2). Introduction of guidelines to reject all SSCYE cultures from patients hospitalized for >3 days who did not meet specified criteria was associated with an overall reduction of 689 (43%) in the volume of tests performed in the 6-month period evaluated. This included 497 fewer cultures ordered and 192 cultures that were ordered but rejected because screening criteria were not met. Only 11 (5.4%) of 203 cultures sent >3 days after admission were processed because they met clinical criteria for testing. None were positive. Estimated cost savings were $50 163/year.

CONCLUSIONS

Stool cultures for SSCYE among hospitalized patients have very low diagnostic yield and are extremely overutilized. Simple guidelines, such as rejecting (with few exceptions) cultures from patients hospitalized for >3 days, can reduce substantially such unnecessary testing.

Controlled comparison of bioMérieux VITAL and BACTEC NR-660 systems for detection of bacteremia and fungemia in pediatric patients

The bioMérieux VITAL automated blood culture system measures a decrease in fluorescence to detect the presence of microorganisms in blood. To assess the performance of VITAL with AER aerobic medium versus that of the nonradiometric BACTEC NR-660 PEDS PLUS medium for the detection of sepsis in children, a total of 12,146 blood specimens were collected at three university medical centers and inoculated into AER and PEDS PLUS bottles that were weighed before and after filling. The sample volumes were considered adequate in 6,276 bottle pairs. The total yield of isolates was 629, of which 489 (78%) were judged to be the cause of true infections. Staphylococci (P < 0.001) and yeasts (P < 0.05) were detected more often in PEDS PLUS bottles, as were all microorganisms combined (P < 0.001). The improved detection in the PEDS PLUS medium was most marked for patients on antimicrobial therapy (P < 0.001), but remained statistically significant even for patients not on therapy (P < 0.025). There were 431 episodes of sepsis, including 407 considered adequate for analysis. Of the 363 unimicrobial episodes, 278 were detected by both bottles, 64 were detected by PEDS PLUS bottles only, and 21 were detected by AER bottles only (P < 0.01). No false-negative cultures were detected by terminal subculture of the PEDS PLUS bottles when the companion AER bottle was positive. However, there were 14 false-negative cultures (7 yeasts, 5 staphylococci, 1 Enterococcus faecalis, and 1 Enterobacter sp.) on terminal subculture of the AER bottles when the companion PEDS PLUS bottle was positive. When both systems were positive, the VITAL system detected bacteria earlier than did the BACTEC system by a mean of 1.6 h. Also, false-positive signals were less common with the VITAL system. We conclude that the VITAL system with AER medium must be modified to improve the detection of clinically important staphylococci and yeasts if it is to perform comparably to the BACTEC NR-660 nonradiometric system with PEDS PLUS medium for a pediatric population.

Assessment of similarity among coagulase-negative staphylococci from sequential blood cultures of neonates and children by pulsed-field gel electrophoresis

One of the criteria used to determine the clinical importance of coagulase-negative staphylococci (CoNS) is isolation of the bacteria from sequential blood cultures. Pulsed-field gel electrophoresis was used to characterize sequential blood isolates of CoNS collected within a 7-day period from neonates and children with bacteremia. Of 18 episodes among neonates, 6 (33%) involved unrelated strains of CoNS. All unrelated strains were from neonates who received antimicrobial therapy after the first culture and who had a second culture > or = 36 h later. Among older children, 5 (19%) of the 27 episodes of presumed central venous (CV) catheter-related sepsis involved unrelated isolates. All of the unrelated isolates were from patients who had blood samples obtained through CV catheters only. Thus, even repeated isolation of CoNS from blood cultures may represent contamination if samples are drawn through CV catheters only or if second samples are obtained > 1 day after appropriate antimicrobial therapy.

Comparison of Isolator 1.5 and BACTEC NR660 aerobic 6A blood culture systems for detection of fungemia in children

The Isolator 1.5 microbial system (ISO 1.5) (Wampole Laboratories, Cranbury, N.J.) was compared with the BACTEC NR660 aerobic NR6A bottle (NR6A) (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) for the detection of fungemia in hospitalized pediatric patients. For 4,825 paired blood cultures evaluated retrospectively from April 1992 to December 1994, at least one blood culture system was positive for 89 clinically important fungal isolates involved in 36 episodes of fungemia in 34 patients. Sixty isolates (44 Candida albicans, 12 Candida parapsilosis, and 4 Candida tropicalis isolates) were recovered from both systems, 13 were recovered from NR6A bottles only (10 C. albicans, 1 C. parapsilosis, and 2 Cryptococcus neoformans isolates), and 16 were recovered from ISO 1.5 tubes only (8 C. albicans and 5 C. parapsilosis isolates and 1 C. tropicalis, 1 Candida lusitaniae, and 1 Rhodotorula glutinis isolate) (P > 0.05). For the 60 Candida isolates from both systems, the mean time to detection was the same in each system. Thirty-seven isolates were detected by both systems on the same day, 9 isolates were detected earlier by NR6A, and 14 isolates were detected earlier by ISO 1.5 (P > 0.05). Of the 36 clinically important episodes of fungemia, 22 were detected by both systems (13 C. albicans isolates and 9 other Candida isolates), 4 were detected by NR6A only (3 C. albicans isolates and 1 C. neoformans isolate), and 10 were detected by ISO 1.5 only (3 C. albicans isolates, 6 other Candida isolates, and 1 R. glutinis isolate) (P > 0.05). Of the 22 episodes in which cultures from both systems were positive at some point during the episode, 12 were detected on the same day by both systems, 8 were detected earlier by NR6A, and 2 were detected earlier by ISO 1.5. Thus, for our pediatric population, NR6A is comparable to ISO 1.5 in both yield and time to detection of yeasts in fungemic patients.

Rejection criteria for endotracheal aspirates from pediatric patients

Endotracheal aspirates (ETAs) from mechanically ventilated pediatric patients frequently are cultured as part of an evaluation for suspected sepsis. There are now well-defined criteria for rejecting low-yield ETAs from adults, but it is uncertain whether the same criteria can be applied to ETAs from children. Therefore, we compared the Gram stain and culture results for 361 consecutive ETA specimens collected from pediatric patients over a 1-year period. Results for patients for whom a blood culture was performed within 48 h of the time that a culture of ETA was performed were also reviewed. Gram stains were examined under x100 magnification to quantitate the number of polymorphonuclear neutrophils and squamous epithelial cells (SECs) per low-power field and under x1,000 magnification for the presence of organisms. No organisms were seen by Gram staining in 225 (62%) of the ETAs. Culture of these specimens rarely yielded useful information: 52% were sterile, 32% grew rare to 1+ quantities of expected respiratory flora only, 12% grew rare to 1+ quantities of gram-negative rods mixed with expected respiratory flora, and only 10 (4%) yielded a pure or predominant growth of a potential respiratory pathogen. Unlike adult patients, we did not find the number of SECs to be a useful screening criterion. Only 17 (5%) of the ETAs had greater than 10 SECs per low-power field, and 5 (29%) of these yielded pure growth of a gram-negative rod. When blood culture results were positive, they correlated with ETA culture results in only 6 of 10 cases. On the basis of our findings, the absence of organisms on Gram staining is a useful criterion for rejecting ETAs from pediatric patients for culture and would have excluded 62% of the specimens from further processing.

Value of routine anaerobic blood cultures for pediatric patients

OBJECTIVE

Anaerobic bacteremia rarely occurs in children. Therefore we assessed the usefulness of routinely obtaining anaerobic blood cultures in our pediatric patients.

STUDY DESIGN

Records of 9360 paired aerobic anaerobic blood culture bottles (Bactec NR660 System) containing blood specimens from pediatric inpatients and outpatients at Duke University Medical Center, Durham, N.C., were reviewed retrospectively. Yield and speed of detection were calculated for each bottle and compared for statistical significance by the McNemar test.

RESULTS

A total of 723 clinically important microorganisms were isolated; only 15 (2.1%) were strict anaerobes. Significantly more microorganisms (p < 0.001), especially staphylococci, nonfermenting gram-negative rods, enteric gram-negative rods, and yeasts, were detected by use of the aerobic bottle. The anaerobic bottle was important in identifying an anaerobic microorganism as the cause of sepsis in only five patients, all of whom were at increased risk of having anaerobic infection.

CONCLUSIONS

Anaerobic blood cultures are rarely helpful in the majority of pediatric patients and usually show positive results only in clinical settings associated with anaerobic infection. Microorganisms that prefer an aerobic environment, such as Pseudomonas aeruginosa and yeasts, are now far more common than anaerobes in children; aerobic culturing of the entire volume of blood collected might increase the yield from pediatric blood cultures.