Staphylococcal Infection

Bacteriology

Bacteriology

Gm +ve cocci Cluster Facultative Nonfastidious

Classification

Classification

Staph. Aureus; Coagulase positive

Staph. Epidermidis; Coagulase negative

Staph. Aureus Infections

Mechanism of pathogenesis;

1-coenzymes local destruction

2-Secretion of Toxins

3-Superantigens activating T cell receptors

4-Interfer with opsonophagocytosis

Epidemiology

Normal human flora; nose& moist areas

Transmission; Hands/nose sec/contact/rarely air. Colonize; skin, newborn nasoph& umb.

Invasion; Skin breaks, I/V access, immune defect, steroids and neutropenea.

Clinical conditions

Clinical conditions

Suppurative.

Toxic related;

Clinical conditions

Suppurative.

Toxic related;

Scalded Skin Syndrome SSS

Toxic Shock Syndrome

??Kawasaki’ Disease

Food poisoning

Skin

Foliculitis

Furaculosis (Boils)/Carbunkles

Emptigo contagoesa

Bullous Emptigo

SSS (Ritter disease)

Respiratory Infections

Sinusitis

Parotitis

Cervical adenitis

Tracheitis compared to croup

Pnumonia;

Sepsis

Start as focal lesion e.g. a boil

Yield to septicemia

Localize to organs e.g. lung, bone, heart, brain etc

Muscles/Bone/Joints

Tropical pyomyositis;

Localized abscesses and high CPK

Osteomylitis;

Trauma/Sx, pain, fever

Septic arthritis;

Usually hematogenous

CNS

Meningitis;

Bacteremea, O.M, skull osteo., neural canal defects.

Neurosurgical procedures and VP shunt

Heart

Bacterial endocarditis;

-Perforated heart valve

-myocardial abscess

-purulent pericarditis

-Sudden death

Kidney

Perinephric abscess

UTI;

Staph. saprophyticus (CONS)

Sexually active adolescent girls

G.I.

Food poisoning;

Meat, mayonnase, creamed foods

Short incubation period of 1 to 7 HRs

Perfuse vomiting, no fever

Test susp. food for staph bacteria/ toxins

Diagnosis

Isolate staph. bacteria

Gram stain

Identify Toxins

Treatment

Penicillinase resistant antibiotics;

Oxacillin (Cloxacillin, Flucloxacillin)

methicillin

Nafcillin

1st generation cephalosporine, cefazolin

(Ultracef)

Treatment cont.

Betalacamase hyperprodcer staph.;

Amoxicillin/Clavulenic acid(Augumentin)

Ampicillin/Salbactam

Imipenem

Fluoroquinilones

1st generation cephalosporin

Vancomycin

Coagulase negative Staph. (CONS)

Common Skin Flora Ubiquitous organism Has affinity to plastic (surface hydophobicity

& production of slim) Neonates, I/V access and shunt devices

infections (nosocomial infections)

Clinical Conditions

Premature neonatal sepsis/NEC. Older children sepsis is rare (minimal signs

of sepsis) Persistent pactreamia usual with indwelling

devices (I/V cath, VP shunt, cardiac grafts and prosthesis etc.)

Clinical Cond. Cont.

Single positive blood culture is a contaminant

UTI in adolescent girls Staphylococcus Saprophyticus (CONS)

Treatment

Remove the access devices/shunts.

May externalize the VP shunt.

Vancomycin or Rifampin.

Amoxicillin or Quinolones for the Staph Saprophyticus UTI.

Nosocomial Infections

Definition

Infections not present or incubating at the time of admission that develop during

admission or less than one incubation period after discharge

Definition cont.

Infections 48 HRs or more after admission is assumed to be nosocomial unless the infection is clearly community acquired

Clean Surgery

Clean Surgery

Incision through prepared normal skin and the operative field dose not include infected

tissue , abscess, or entry into normally unsterile areas such as the bowel, the upper respiratory tract, or the lower female genital

tract.

Rate of Nosocomial Infections

Number of nosocomial infections divided by the number of patients at risk multiplied by

100

Epidemiology

1/3 hospital infections are nosocomial (estimate in the USA)

i.e. 2 million patients

i.e. 4 million patient days of hospitalization

i.e. 4.5 Billion USD

i.e. 17 Billion SAR

Epidemiology cont.

In USA (1978) nosocomial inf. rate;

-All services 3.37%

-Pediatric services 1.2%

Epidemiology cont.

Common sites of ped. nosocomial infections (as per the NNIS);

Blood stream Surgical sites Lower respiratory tract Urinary tract

Epidemiology cont.

In adults;

Urinary tract Surgical sites Lower respiratory tract Blood stream

Epidemiology cont.

Common PEDIATRIC nosocomial bacteria; Staphylococcus aureus Escherichia coli CONS Klebsiella

Epidemiology cont.

Common NEONATAL nosocomial bacteria; CONS Staphylococcus aureus Escherichia coli Group B sterptococci Klebsiella

Epidemiology cont.

Areas of high nosocomial infection rates; NICU PICU Burn Units

Risk Factors of Nosocomial Inf.

General risk factors; Prior colonization with nosocomially acquired bacteria Catheters Exposure to antibiotics

• Specific risk factors Inhalation equipments Specific monitoring cath’s e.g. arterial cath etc. Viral infections

General risk factors

Prior colonization; Klebsiella colonization after admission gave

50% incidence of infection Inhalation therapy, N/G suction and

antibiotics are behind the colonization

General risk factors

Catheters; Increase risk of septicemia with method of

insertion, type of solution and duration of placement (I/V catheter)

Major risk of septicemia in neonates Urine catheter is a risk for UTI in females,

elderly and critical pt.’s Risk increase with method of insertion, length

of tube and break of the system

General risk factors

Exposure to Antibiotics; Prior use of broad spectrum antibiotics Normal flora protect the host through

blocking the surface receptor/attachment sites

Specific risk facors

Special catheters Pressure trasducers Arterial catheters Swan-Ganz catheters

Specific risk facors

Viral infections RSV close contact with infants at risk Varicella ( 8-21 days incubation) and risk for

nonimmune and immune suppressed. Screen hospital personnel

Rota virus

Prevention and control of nosocomial infections

General measures; A team of infection control team Enforce surveillance of equipments,

disinfection and isolation techniques

Specific risk factors

Inhalation equipments Nebulizers and humidifiers Risk of necrotizing pneumonia Decontamination with .25% acetic acid and

ethylene oxide

Prevention and control of nosocomial infections

Universal precautions; Barrier precautions prevent exposure Hand wash Proper handling of sharp instruments Resuscitation equipments Personnel with exudative lesions Pregnant health workers

Prevention and control of nosocomial infections

Isolation techniques;

Apply specific isolation to specific diseases

Prevention and control of nosocomial infections

Hand wash practice; Most effective and least expensive practice

to prevent transmission of pathogens Educate personnel of the method of hand

wash (15 seconds with warm water and soap then dry and turn faucet with towel)

Prevention and control of nosocomial infections

Intravenous therapy; Hand wash Clean site with 70% alcohol and 10% providone-

iodine Preferred locations in pediatrics are scalp, hands

and foot Minimize duration if possible Prophylactic antibiotics are not recommended Remove catheter if sign of inflammation